Patent Publication Number: US-2012033701-A1

Title: Method of manufacturing semiconductor laser device, semiconductor laser device and light apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The priority application number JP2009-014478, Method of Manufacturing Semiconductor Laser Device and Semiconductor Laser Device, Jan. 26, 2009, Yasuyuki Bessho et al, JP2009-103507, Method of Manufacturing Semiconductor Laser Device, Apr. 22, 2009, Yasuyuki Bessho et al, JP2010-7892, Method of Manufacturing Semiconductor Laser Device, Semiconductor Laser Device and Light Apparatus, Jan. 18, 2010, Yasuyuki Bessho et al, upon which this patent application is based is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of manufacturing a semiconductor laser device, a semiconductor laser device, and a light apparatus, and more particularly, it relates to a method of manufacturing a semiconductor laser device formed by bonding a first semiconductor laser device and a second semiconductor laser device, a semiconductor laser device and a light apparatus. 
     2. Description of the Background Art 
     A method of manufacturing a semiconductor laser device formed by bonding a first semiconductor laser device and a second semiconductor laser device is known in general, as disclosed in Japanese Patent Laying-Open No. 2005-327905, for example. 
     The aforementioned Japanese Patent Laying-Open No. 2005-327905 discloses a semiconductor light-emitting device (semiconductor laser device) comprising a first light-emitting element bonded onto a support base and a second light-emitting element bonded onto a surface of a semiconductor layer of the first light-emitting element and formed with a first element and a second element. This semiconductor light-emitting device described in Japanese Patent Laying-Open No. 2005-327905 is provided with notch grooves on a semiconductor layer of the first light-emitting element opposed to a light-emitting point of the first element and a light-emitting point of the second element. This pair of notch grooves can inhibit light from the light-emitting points of the first and second elements from being radiated in an undesirable direction by reflection on the semiconductor layer of the first light-emitting element. In a method of manufacturing the semiconductor light-emitting device, the semiconductor light-emitting device is formed by bonding the first and second light-emitting elements each previously worked into a chip. 
     In the aforementioned semiconductor light-emitting device disclosed in Japanese Patent Laying-Open No. 2005-327905, however, since the first and second light-emitting elements each previously worked into a chip are bonded to each other, it is disadvantageously difficult to locate a cavity facet (light-emitting surface) of the first light-emitting element and a cavity facet of the second light-emitting element on the same surface. 
     SUMMARY OF THE INVENTION 
     A method of manufacturing a semiconductor laser device according to a first aspect of the present invention comprises steps of forming a first semiconductor laser device substrate having first grooves for cleavage on a surface thereof, bonding a second semiconductor laser device substrate onto the surface having the first grooves and thereafter cleaving the first and second semiconductor laser device substrates along at least the first grooves to form cleavage planes on the first and second semiconductor laser device substrates. 
     As hereinabove described, the method of manufacturing a semiconductor laser device according to the first aspect of the present invention comprises the steps of bonding the second semiconductor laser device substrate onto the surface having the first grooves and thereafter cleaving the first and second semiconductor laser device substrates along at least the first grooves to form the cleavage planes on the first and second semiconductor laser device substrates, whereby the first and second semiconductor laser device substrates are simultaneously cleaved in a state where the second semiconductor laser device substrate is bonded onto the surface side, having the first grooves, of the first semiconductor laser device substrate, and hence cavity facets consisting of cleavage planes can be simultaneously formed on the first and second semiconductor laser device substrates. Thus, the cavity facets of the first semiconductor laser device substrate and the cavity facets of the second semiconductor laser device substrate can be easily located on the same surface. Each of the “first semiconductor laser device substrate” and the “second semiconductor laser device substrate” shows a state before dividing the semiconductor laser device, and includes both of a substrate in a state where a semiconductor device layer is not formed on the substrate and a substrate in a state where the semiconductor device layer is formed on the substrate. 
     In the aforementioned method of manufacturing a semiconductor laser device according to the first aspect, the step of forming the first semiconductor laser device substrate having the first grooves on the surface thereof preferably includes a step of forming the first grooves in the form of broken lines on a region except waveguides of the first semiconductor laser device substrate and the vicinity thereof. According to this structure, the first grooves are formed on positions separated from the waveguides of the first semiconductor laser device substrate which are light-emitting portions and regions in the vicinity thereof, and hence the waveguides of the first semiconductor laser device substrate can be inhibited from being damaged also when the first grooves are formed. The first grooves can be formed to extend on an substantially overall area except the waveguides of the first semiconductor laser device substrate and the vicinity thereof, and hence the first and second semiconductor laser device substrates can be more reliably cleaved. 
     In the aforementioned structure including the step of forming the first grooves in the form of the broken lines, the step of forming the first semiconductor laser device substrate preferably includes a step of forming the first grooves in a direction substantially perpendicular to an extensional direction of the waveguides. According to this structure, the first and second semiconductor laser device substrates can be cleaved along the direction substantially perpendicular to the extensional direction of the waveguides by the first grooves, and hence the cavity facets consisting of the cleavage planes substantially perpendicular to the waveguides can be easily formed. 
     In the aforementioned structure including the step of forming the first grooves in the form of the broken lines, the first semiconductor laser device substrate preferably includes a first substrate and a first semiconductor device layer formed on a surface of the first substrate, and the step of forming the first semiconductor laser device substrate preferably includes a step of forming the first grooves each having a depth reaching the first substrate from the surface of the first semiconductor device layer. According to this structure, the thickness of the first substrate formed with no the first grooves is further reduced due to the first grooves each having the depth reaching the first substrate from the surface of the first semiconductor device layer also when the first semiconductor laser device substrate is formed by a nitride-based semiconductor which is generally difficult to be cleaved, for example, and hence the first semiconductor laser device substrate made of the nitride-based semiconductor can be more easily cleaved. 
     In the aforementioned structure including the step of forming the first grooves in the form of the broken lines, the step of forming the first semiconductor laser device substrate preferably includes a step of forming the first grooves so that at least first ends of the first grooves have wedge shapes in plan view. According to this structure, cracks are easily formed on sections from the first ends of the first grooves to the ends of the first grooves adjacent thereto when cleaving the first semiconductor laser device substrate, and hence the first and second semiconductor laser device substrates can be easily cleaved. 
     The aforementioned method of manufacturing a semiconductor laser device according to the first aspect preferably further comprises a step of forming second grooves on the second semiconductor laser device substrate at positions overlapping with regions formed with the first grooves in plan view after the step of bonding the second semiconductor laser device substrate, wherein the step of cleaving along the first grooves includes a step of cleaving the first and second semiconductor laser device substrates simultaneously along the first and second grooves. According to this structure, the first and second semiconductor laser device substrates can be cleaved simultaneously along the first and second grooves, and hence the first and second semiconductor laser device substrates can be more reliably cleaved as compared with a case where only the first grooves are cleaved. Thus, the more excellent cavity facets (cleavage planes) can be obtained not only on the first semiconductor laser device substrate also on the second semiconductor laser device substrate. 
     In the aforementioned structure further comprising the step of forming the second grooves, the step of forming the second grooves preferably includes a step of forming the second grooves on a surface on an opposite side of the second semiconductor laser device substrate to the first semiconductor laser device substrate. According to this structure, positions of the second grooves formed on the second semiconductor laser device substrate can be easily recognized, and hence pressing force for simultaneously cleaving the first and second semiconductor laser device substrates can be suitably applied while confirming the positions of the second grooves. 
     In the aforementioned structure further comprising the step of forming the second grooves, the step of forming the second grooves preferably includes a step of forming the second grooves in the vicinity of ends of the second semiconductor laser device substrate. According to this structure, the second semiconductor laser device substrate can be easily cleaved, and the cavity facets of the first and second semiconductor laser device substrates can be inhibited from being deviated in a cavity direction due to deviation of the first and second grooves when the second grooves are formed on an overall surface of the second semiconductor laser device substrate. 
     In the aforementioned structure further comprising the step of forming the second grooves, the step of forming the second grooves preferably includes a step of forming the second grooves in the form of broken lines on the second semiconductor laser device substrate. According to this structure, the second grooves can be formed in the form of the broken lines on a substantially overall area of the second semiconductor laser device substrate along an extensional direction of the first grooves. Therefore, regions formed with the second grooves are increased and hence the second semiconductor laser device substrate can be more easily cleaved. 
     The aforementioned method of manufacturing a semiconductor laser device according to the first aspect preferably further comprises a step of removing needless regions consisting of one part of the second semiconductor laser device substrate after the step of cleaving along the first grooves. According to this structure, device division can be performed on the portion of only the first semiconductor laser device substrate where no second semiconductor laser device substrate exists when the wafer after removing the needless regions consisting of the one part of the second semiconductor laser device substrate is divided into chips in subsequent steps, and hence a chip of the multiple wavelength semiconductor laser device can be easily obtained. 
     In the aforementioned structure further comprising the step of removing the needless regions, the step of removing the needless regions preferably includes a step of removing the needless regions simultaneously when the first and second semiconductor laser device substrates bonded to each other are divided into chips. According to this structure, the needless regions are removed simultaneously when the wafer where the first and second semiconductor laser device substrates are bonded is divided into chips, and hence the manufacturing process can be simplified as compared with a case where the step of dividing the wafer into chips and the step of removing the needless regions are separately performed. 
     The aforementioned structure further comprising the step of removing the needless regions preferably further comprises a step of forming protective films on the cleavage planes in advance of the step of removing the needless regions. According to this structure, the wafer in which the first and second semiconductor laser device substrates are bonded to each other is formed with protective films (insulating films) on the cavity facets (cleavage planes) in a state where the wafer has a substantially uniform thickness. Thus, a disadvantage that the electrode layer is insulated by the protective films extending toward and covering the surfaces of the exposed electrode layer does not occur dissimilarly to a case where the needless regions are removed to expose the electrode layer on the first semiconductor laser device substrate side before forming the protective films and the protective films, for example, and hence a wire bonded after division into chips and the electrode layer can be reliably electrically connected (wire-bonded). 
     The aforementioned structure further comprising the step of removing the needless regions preferably further comprises a step of forming second grooves on the second semiconductor laser device substrate at positions overlapping with regions formed with the first grooves in plan view after the step of bonding the second semiconductor laser device substrate, wherein the step of forming the second grooves includes a step of forming the second grooves on the needless regions. According to this structure, only cavity facets consisting of cleavage planes employing the second grooves removed together with the needless regions as starting points of cracks can be easily formed on regions remaining on a chip of the second semiconductor laser device substrate, dissimilarly to a case where the second grooves remain the regions remaining on the chip of the second semiconductor laser device substrate. 
     The aforementioned structure further comprising the step of removing the needless regions preferably further comprises steps of forming first device division grooves on the first semiconductor laser device substrate and forming second device division grooves for removing the needless regions on a surface of the second semiconductor laser device substrate, in advance of the step of removing the needless regions. According to this structure, the second semiconductor laser device substrate can be also divided on positions formed with the second device division grooves into regions remaining on the chips and regions removed from the chips in response to division of the first semiconductor laser device substrate on the portions of the first device division grooves when dividing the wafer. Thus, the needless regions can be easily removed while the wafer is simultaneously divided into chips 
     In this case, the method preferably further comprises a step of forming third device division grooves at positions overlapping with regions formed with the second device division grooves in plan view on a surface on an opposite side of the second semiconductor laser device substrate to the surface of the second semiconductor laser device substrate formed with the second device division grooves, in advance of the step of bonding the second semiconductor laser device substrate. According to this structure, in the second semiconductor laser device substrate, the wafer (substrate) is easily partially divided not only by the second device division grooves but the third device division grooves, and hence the needless regions can be more easily removed. 
     In the aforementioned structure further comprising the step of removing the needless regions, an electrode layer is preferably formed on a surface of the first semiconductor laser device substrate on a side bonded with the second semiconductor laser device substrate, and the electrode layer is formed to be exposed by the step of removing the needless regions. According to this structure, a wire can be easily bonded onto the portion of the electrode layer exposed on the surface of the first semiconductor laser device substrate by partially removing the second semiconductor laser device substrate. 
     In the aforementioned method of manufacturing a semiconductor laser device according to the first aspect, the second semiconductor laser device substrate preferably includes a second substrate and a second semiconductor device layer, and the step of bonding the second semiconductor laser device preferably includes a step of bonding a surface of the second semiconductor device layer of the second semiconductor laser device substrate onto the surface having the first grooves. According to this structure, the second semiconductor device layer of the second semiconductor laser device substrate can be located on the first semiconductor laser device substrate side, and hence light-emitting points of the first semiconductor laser device substrate and light-emitting points of the second semiconductor laser device substrate can be brought close to each other. 
     A semiconductor laser device according to a second aspect of the present invention comprises a first semiconductor laser device substrate including a first semiconductor laser device and a second semiconductor laser device substrate including a second semiconductor laser device, wherein the second semiconductor laser device is bonded onto a surface of the first semiconductor laser device, and the first semiconductor laser device includes step portions consisting of portions, each of which was a part of the groove for cleavage in a state where the first and second semiconductor laser device substrates are bonded to each other, on the surface of the first semiconductor laser device. 
     According to the aforementioned structure, in the semiconductor laser device according to the second aspect of the present invention, the first and second semiconductor laser device substrates which are in a bonded state are cleaved along the grooves, and hence it is possible that cavity facets of the first semiconductor laser device and cavity facets of the second semiconductor laser device are not deviated in a cavity direction. Thus, the semiconductor laser device where the cavity facets of the first semiconductor laser device and the cavity facets of the second semiconductor laser device are located on the same surface can be obtained. 
     In the aforementioned semiconductor laser device according to the second aspect, the step portions are preferably formed on regions except waveguides of the first semiconductor laser device and the vicinity thereof to extend along a direction substantially perpendicular to an extensional direction of the waveguides. According to this structure, in the manufacturing process, the grooves for cleavage (step portions) are formed on positions separated from the waveguides of the first semiconductor laser device substrate which are light-emitting portions and regions in the vicinity thereof when cleaving the first and second semiconductor laser device substrates which are in the bonded state along the grooves, and hence cleavage can be performed while suppressing damage to the waveguides of the first semiconductor laser device substrate. Further, the first and second semiconductor laser device substrates can be cleaved along the direction substantially perpendicular to the extensional direction of the waveguides, and hence the cavity facets consisting of cleavage planes, substantially perpendicular to the waveguides can be easily formed. 
     A light apparatus according to a third aspect of the present invention comprises a semiconductor laser device having a first semiconductor laser device substrate including a first semiconductor laser device and a second semiconductor laser device substrate including a second semiconductor laser device, and an optical system controlling a light emitted from the semiconductor laser device, wherein the second semiconductor laser device is bonded onto a surface of the first semiconductor laser device, and the first semiconductor laser device has step portions consisting of portions, each of which was a part of the groove for cleavage in a state where the first and second semiconductor laser device substrates are bonded to each other, on the surface of the first semiconductor laser device. 
     According to the aforementioned structure, in the light apparatus according to the third aspect of the present invention, the semiconductor laser device can be formed by cleaving the first and second semiconductor laser device substrates which are in a bonded state along the grooves can be formed, and hence, it is possible that the cavity facets of the first semiconductor laser device and the cavity facets of the second semiconductor laser device are not deviated in a cavity direction. Thus, the light apparatus comprising the semiconductor laser device where the cavity facets of the first semiconductor laser device and the cavity facets of the second semiconductor laser device are located on the same surface can be obtained. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a structure of a semiconductor laser device formed by a manufacturing method according to a first embodiment of the present invention; 
         FIG. 2  is a sectional view taken along the line  1000 - 1000  of the semiconductor laser device shown in  FIG. 1 ; 
         FIG. 3  is a sectional view taken along the line  2000 - 2000  of the semiconductor laser device shown in  FIG. 1 ; 
         FIG. 4  is a sectional view taken along the line  3000 - 3000  of the semiconductor laser device shown in  FIG. 1 ; 
         FIG. 5  is a top plan view showing the structure of a semiconductor laser device formed by the manufacturing method according to the first embodiment shown in  FIG. 1 ; 
         FIGS. 6 to 14  are diagrams for illustrating a process of manufacturing the semiconductor laser device according to the first embodiment shown in  FIG. 1 ; 
         FIGS. 15 to 17  are diagrams for illustrating a process of manufacturing a semiconductor laser device according to a modification of the first embodiment of the present invention; 
         FIG. 18  is a diagram showing a structure of a semiconductor laser device formed by employing a manufacturing method according to a second embodiment of the present invention; 
         FIG. 19  is a diagram showing a structure of a semiconductor laser device formed by a manufacturing method according to a third embodiment of the present invention; 
         FIG. 20  is a diagram showing a structure of a semiconductor laser device formed by a manufacturing method according to a fourth embodiment of the present invention; 
         FIG. 21  is a diagram showing a structure of a semiconductor laser device formed by a manufacturing method according to a fifth embodiment of the present invention; 
         FIG. 22  is a perspective view showing a structure of a semiconductor laser device formed by a manufacturing method according to a sixth embodiment of the present invention; 
         FIG. 23  is a block diagram of an optical pickup having a build-in semiconductor laser apparatus mounted with a semiconductor laser device according to a seventh embodiment of the present invention; 
         FIG. 24  is an external perspective view showing a schematic structure of the semiconductor laser apparatus mounted with the semiconductor laser device according to the seventh embodiment of the present invention; 
         FIG. 25  is a front elevational view of a state where a lid body of a can package of the semiconductor laser apparatus mounted with the semiconductor laser device according to the seventh embodiment of the present invention is removed; 
         FIG. 26  is a block diagram of an optical disc apparatus comprising an optical pickup mounted with a semiconductor laser device according to an eight embodiment of the present invention; 
         FIG. 27  is a front elevational view showing a structure of a semiconductor laser apparatus mounted with a semiconductor laser device according to a ninth embodiment of the present invention; 
         FIG. 28  is a block diagram of a projector mounted with a semiconductor laser device according to the ninth embodiment of the present invention; 
         FIG. 29  is a block diagram of a projector mounted with a semiconductor laser device according to a tenth embodiment of the present invention; 
         FIG. 30  is a timing chart showing a state where a control portion transmits signals in a time-series manner in the projector mounted with the semiconductor laser device according to the tenth embodiment of the present invention; 
         FIG. 31  is a top plan view showing shapes of first cleavage guide grooves formed in a process of manufacturing a semiconductor laser device according to a first modification of the present invention; 
         FIG. 32  is a top plan view showing shapes of first cleavage guide grooves formed in a process of manufacturing a semiconductor laser device according to a second modification of the present invention 
         FIG. 33  is a top plan view showing shapes of first cleavage guide grooves formed in a process of manufacturing a semiconductor laser device according to a third modification of the present invention; and 
         FIG. 34  is a top plan view showing shapes of second cleavage guide grooves formed in a process of manufacturing a semiconductor laser device according to a fourth modification of the present invention; and 
         FIG. 35  is a top plan view showing shapes of second cleavage guide grooves formed in a process of manufacturing a semiconductor laser device according to a fifth modification of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention will be hereinafter described with reference to the drawings. 
     First Embodiment 
     A structure of a semiconductor laser device  100  according to a first embodiment will be now described with reference to  FIGS. 1 to 5 .  FIG. 2  is a sectional view taken along the line  1000 - 1000  of the semiconductor laser device shown in  FIG. 1 , and  FIG. 3  is a sectional view taken along the line  2000 - 2000 .  FIG. 4  is a sectional view taken along the line  3000 - 3000 , and  FIG. 5  is a top plan view. 
     The semiconductor laser device  100  formed by a manufacturing method according to the first embodiment of the present invention is formed with a blue-violet semiconductor laser device portion  11  having a lasing wavelength of about 405 nm on a surface of an n-type GaN substrate  10  having a thickness of about 100 μm in a direction (direction Z) of stacking of semiconductor layers, as shown in  FIGS. 1 and 2 . 
     A two-wavelength semiconductor laser device portion  30  monolithically formed with a red semiconductor laser device portion  21  having a lasing wavelength of about 650 nm and an infrared semiconductor laser device portion  22  having a lasing wavelength of about 780 nm is formed on a surface of an n-type GaAs substrate  20  having a thickness of about 100 μm in the direction (direction Z) of stacking of the semiconductor layers. The red semiconductor laser device portion  21  is bonded onto an upper surface of the blue-violet semiconductor laser device portion  11  on a Y 1  side and the infrared semiconductor laser device portion is bonded onto the upper surface of the blue-violet semiconductor laser device portion  11  on a Y 2  side. The “first semiconductor laser device” of the present invention is constituted by the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11 , and the “second semiconductor laser device” of the present invention is constituted by the n-type GaAs substrate  20  and the two-wavelength semiconductor laser device portion comprising the red and infrared semiconductor laser device portions  21  and  22 . 
     As shown in  FIGS. 1 to 3 , in the blue-violet semiconductor laser device portion  11 , an n-type cladding layer  11   a  made of n-type AlGaN, an active layer  11   b  having a multiple quantum well (MQW) structure and a p-type cladding layer  11   c  made of p-type AlGaN are stacked on a surface of the n-type GaN substrate  10 . As shown in  FIGS. 1 and 2 , the p-type cladding layer  11   c  has a projecting portion formed on a substantially central portion in a direction Y and projecting upward (in the direction Z 1 ) and planar portions extending to both sides of the projecting portion. The projecting portion of the p-type cladding layer  11   c  forms a ridge  11   d  for constituting an optical waveguide on a portion of the active layer  11   b . The ridge  11   d  is formed to extend in a direction X, as shown in  FIGS. 1 ,  4  and  5 . 
     According to the first embodiment, in the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11 , step portions  10   a  and  11   e  are formed on both ends of the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  on the X sides and on both side surface sides of the ridge  11   d  in the direction Y, respectively, as shown in  FIGS. 1 and 3 . These step portions  10   a  and  11   e  are portions where first cleavage guide grooves  40   a  remain on the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  after dividing a wafer-state semiconductor laser device  200  along in the direction Y (bar-shaped cleavage) in a manufacturing process described later. 
     As shown in  FIGS. 1 and 2 , a first insulating layer  11   f  made of SiO 2  is formed on the side surfaces of the ridge  11   d  of the p-type cladding layer  11   c  and the upper surfaces of the planar portions. This first insulating layer  11   f  is stacked also on the step portions  10   a  and  11   e . A p-side electrode  11   g  is formed on an upper surface of the first insulating layer  11   f . This p-side electrode  11   g  is provided not on an overall surface of the first insulating layer  11   f  and but up to the vicinity of four ends of the first insulating layer  11   f  (both ends in the directions X and Y). The second insulating layer  11   h  made of SiO 2  is formed on the upper surface of the p-side electrode  11   g  and the upper surface of the four ends of the first insulating layer  11   f . This second insulating layer  11   h  is formed to be stacked on portions, stacked with the first insulating layer  11   f , of the step portions  10   a  and  11   e . As shown in  FIG. 5 , the second insulating layer  11   h  is partially removed on the X 1  side and the Y 1  side of the second insulating layer  11   h , so that a wire bonding portion  11   i  formed by partially exposing the p-side electrode  11   g  is formed. 
     A pad electrode  12   a  is formed on the upper surface of the second insulating layer  11   h  on the Y 1  side to avoid the wire bonding portion  11   i  of the blue-violet semiconductor laser device portion  11 . A pad electrode  12   b  is formed on the upper surface of the second insulating layer  11   h  on the Y 2  side. The pad electrodes  12   a  and  12   b  are each an example of the “electrode layer” in the present invention. 
     As shown in  FIGS. 1 to 3 , an n-side electrode  13  is formed on an overall lower surface of the n-type GaN substrate  10 . Step portions  10   b  and  13   a  are formed on both ends of the lower surface of the n-type GaN substrate  10  on the Y sides and both ends of the n-side electrode  13  on the Y sides, respectively. These step portions  10   b  and  13   a  are portions where device division grooves  60   c  remain on the n-type GaN substrate  10  and the n-side electrode  13  after performing device division of a bar-shaped semiconductor laser device  300  along the direction X (in the form of chips) in a manufacturing process described later. The device division groove  60   c  is an example of the “first device division groove” in the present invention. 
     In the red semiconductor laser device portion  21  constituting the two-wavelength semiconductor laser device portion  30 , an n-type cladding layer  21   a  made of n-type AlGaInP, an active layer  21   b  having an MQW structure and a p-type cladding layer  21   c  made of p-type AlGaInP are stacked on a lower surface of the n-type GaAs substrate  20  on the Y 1  side. In the infrared semiconductor laser device portion  22 , an n-type cladding layer  22   a  made of n-type AlGaAs, an active layer  22   b  having an MQW structure and a p-type cladding layer  22   c  made of p-type AlGaAs are stacked on a lower surface of the n-type GaAs substrate  20  on the Y 2  side. As shown in  FIGS. 1 ,  2  and  4 , a groove  20   a  is formed between the red semiconductor laser device portion  21  and the infrared semiconductor laser device portion  22  (central portion in the direction Y). 
     The p-type cladding layers  21   c  and  22   c  have projecting portions formed on substantially central portions in the direction Y and projecting downward (in a direction Z 2 ), recess portions  21   d  and  22   d  formed on both sides of the projecting portions and planar portions  21   e  and  22   e  extending to both sides of the recess portions  21   d  and  22   d , respectively. The projecting portion of the p-type cladding layers  21   c  and  22   c  form ridges  21   f  and  22   f  for constituting optical waveguides on portions of the active layers  21   b  and  22   b , respectively. The ridges  21   f  and  22   f  are formed to extend in the direction X, as shown in  FIGS. 1 and 5 . 
     As shown in  FIGS. 1 and 2 , an insulating layer  23  made of SiO 2  is formed on lower surfaces of the p-type cladding layers  21   c  and  22   c  except lower surfaces of ridges  21   f  and  22   f , side surfaces of the red and infrared semiconductor laser device portions  21  and  22 , and a lower surface of the groove  20   a  of the n-type GaAs substrate  20 . The insulating layer  23  have a substantially uniform thickness and is formed also on inner surfaces (upper and side surfaces) of the recess portions  21   d  and  22   d  of the p-type cladding layers  21   c  and  22   c , respectively. Thus, the insulating layer  23  has recess portions formed on the both sides of the ridges  21   f  and  22   f  and planar portions  23   a  extending to the both sides of the recess portions so as to correspond to the p-type cladding layers  21   c  and  22   c.    
     The planar portions  23   a  are formed to be located below the lower surfaces (surfaces on the Z 2  side) of the ridges  21   f  and  22   f  formed with no insulating layer  23 . Thus, excessive pressure can be inhibited from being applied to the ridges  21   f  and  22   f  when bonding the red and infrared semiconductor laser device portions  21  and  22  onto the blue-violet semiconductor laser device portion  11 . 
     A p-side electrode  24   a  is formed on the lower surface of the ridge  21   f  and a lower surface of the insulating layer  23  located around the ridge  21   f . A p-side electrode  24   b  is formed on the lower surface of the ridge  22   f  and a lower surface of the insulating layer  23  located around the ridge  22   f . Each of the p-side electrodes  24   a  and  24   b  is formed to have unevenness by having a substantially uniform thickness. 
     An n-side electrode  25  is formed on an upper surface of the n-type GaAs substrate  20 . This n-side electrode  25  is formed to be employed for the red and infrared semiconductor laser device portions  21  and  22  in common. Step portions  20   b  and  25   a  are formed on both ends of upper surfaces of the n-type GaAs substrate  20  and the n-side electrode  25  on the Y sides. These step portions  20   b  and  25   a  are portions where device division grooves  60   b  remain on the n-type GaAs substrate  20  and the n-side electrode after performing device division of the bar-shaped semiconductor laser device  300  along in the direction X (in the form of chips) in a manufacturing process described later. The device division groove  60   b  is an example of the “second device division groove” in the present invention. 
     The p-side electrodes  24   a  and  24   b  are bonded onto upper surfaces of the pad electrodes  12   a  and  12   b  through fusion layers  26   a  and  26   b  (see  FIG. 2 ) made of Au—Sn solder, respectively. The step portions  10   a  and  11   e  formed on the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  are formed to extend up to portions located below (in the direction Z 2 ) a position formed with the red or infrared semiconductor laser device portion  21  or  22 . 
     According to the first embodiment, pairs of cavity facets  11   j ,  21   g  and  22   g  are formed on both ends of the blue-violet, red and infrared semiconductor laser device portions  11 ,  21  and  22  on the X sides so as to be flat surfaces perpendicular to the ridges  11   d ,  21   f  and  22   f  (flat surfaces formed by the directions Y and Z), respectively, as shown in  FIG. 5 . The cavity facets  11   j ,  21   g  and  22   g  on the X 1  sides are formed on the same flat surface and the cavity facets  11   j ,  21   g  and  22   g  on the X 2  sides are formed on the same flat surface. A dielectric film  31  and dielectric multilayer films  32  having a function of reflectance control and made of Al 2 O 2 , SiO 2 , and TiO 2  are formed on the cavity facets  11   j ,  21   g  and  22   g  by facet coating treatment in the manufacturing process.  FIG. 1  shows the semiconductor laser device  100  in a state where the aforementioned dielectric film  31  and dielectric multilayer films  32  are not illustrated, for simplification of the drawing. 
     The dielectric film  31  formed on the cavity facets  11   j ,  21   g  and  22   g  on the X 1  side is constituted by an Al 2 O 2  film having a thickness of about 330 nm formed on the cavity facets  11   j ,  21   g  and  22   g . The dielectric multilayer film  32  formed on the cavity facets on the X 2  side is constituted by a multilayer reflecting film formed by alternately stacking two SiO 2  films each having a thickness of about 120 nm and two TiO 2  films each having a thickness of about 75 nm, alternately stacking three SiO 2  films each having a thickness of about 70 nm and three TiO 2  films each having a thickness of about 43 nm, and alternately stacking an SiO 2  film having a thickness of about 70 nm and a TiO 2  film having a thickness of about 40 nm from the cavity facets toward outside, and having a thickness of about 839 nm in total. In this case, the cavity facets  11   j ,  21   g  and  22   g  on the X 1  side of the semiconductor laser device  100  function as a light-emitting surface having relatively larger strength of the emitted laser beam and the cavity facets  11   j ,  21   g  and  22   g  on the X 2  side functions as a light-reflecting surface having relatively smaller strength of the emitted laser beam. 
     The process of manufacturing the semiconductor laser device  100  according to the first embodiment will be now described with reference to  FIGS. 1 ,  2  and  5  to  14 . 
     As shown in  FIG. 6 , a blue-violet semiconductor laser device portion  211  is formed by successively stacking an n-type cladding layer  211   a , an active layer  211   b , a p-type cladding layer  211   c  on an upper surface of a wafer-state n-type GaN substrate  210  by low-pressure MOCVD. The n-type GaN substrate  210  and a blue-violet semiconductor laser device portion  211  are examples of the “first substrate” and the “first semiconductor device layer” in the present invention, respectively. The “first semiconductor laser device substrate” in the present invention is constituted by the n-type GaN substrate  210  and the blue-violet semiconductor laser device portion  211 . 
     In the process of manufacturing the semiconductor laser device  100  of the first embodiment, the first cleavage guide grooves  40   a  having a depth of about 5 μm in the direction Z 2  are formed to extend from the p-type cladding layer  211   c  side (blue-violet semiconductor laser device portion  211  side) of the blue-violet semiconductor laser device portion  211  in the direction Y by photolithography and etching. The first cleavage guide grooves  40   a  extend perpendicular to the ridges  11   d  as viewed from the Z 1  side and have substantially rectangular shapes. The first cleavage guide grooves  40   a  are formed to have substantially rectangular shapes, whereby no complex shaped mask may be required and hence the first cleavage guide grooves  40   a  can be easily formed. At this time, the first cleavage guide grooves  40   a  are formed in the form of broken lines to exclude regions (see  FIG. 7 ) formed with the ridges  11   d  of the blue-violet semiconductor laser device portion  211  of the semiconductor laser device  100  and regions in the vicinity thereof, and are formed to reach not only the blue-violet semiconductor laser device portion  211  but an upper portion of the wafer-state n-type GaN substrate  210 . Thus, the n-type GaN substrate  210  employed as a nitride-based semiconductor which is generally difficult to be cleaved and the blue-violet semiconductor laser device portion  211  can be more reliably cleaved. The first cleavage guide grooves  40   a  is an example of the “first groove” in the present invention. 
     As shown in  FIG. 7 , prescribed regions of the p-type cladding layer  211   c  are removed by photolithography and etching, thereby extending the ridges  11   d  in the direction X. At this time, the depth (about 5 μm) of the first cleavage guide grooves  40   a  is larger than a height of the ridges  11   d , whereby the first cleavage guide grooves  40   a  remain on the blue-violet semiconductor laser device portion  211  also after forming the ridges  11   d.    
     As shown in  FIG. 8 , a first insulating layer  211   f  is formed on the side surfaces of the ridges  11   d  of the p-type cladding layer  211   c  and upper surfaces of the planar portions by plasma CVD. At this time, the first insulating layer  211   f  is stacked also in the first cleavage guide grooves  40   a . Then, after removing the first insulating layer  211   f  formed on the upper surfaces of the ridges  11   d , a metal layer (not shown) is stacked on the upper surfaces of the ridges  11   d  and the upper surface of the first insulating layer  211   f  to correspond to the shape of the n-type GaN substrate  10  of the semiconductor laser device  100  worked into a chip by vacuum evaporation. Then, the metal layer is alloyed by thermal treatment of about 400° C. to form the p-side electrodes  11   g  at regular intervals. 
     A second insulating layer  211   h  is formed on upper surfaces of a plurality of p-side electrodes  11   g  and the upper surface of the first insulating layer  211   f  by plasma CVD. At this time, the second insulating layer  211   h  is stacked also on the upper surface of the first insulating layer  211   f  in the first cleavage guide grooves  40   a . Thereafter, prescribed regions of the second insulating layer  211   h  are removed by photolithography and etching, thereby forming the wire bonding portions  11   i  formed by partially exposing the plurality of p-side electrode  11   g.    
     In order to allow wire-bonding, the pad electrodes  12   a  and  12   b  are formed on the upper surfaces of the prescribed regions of the second insulating layer  211   h  to correspond to the shape of the n-type GaN substrate  10  of the semiconductor laser device  100  worked into a chip by photolithography and vacuum evaporation. Then, the fusion layers  26   a  and  26   b  are formed on the upper surfaces of the pad electrodes  12   a  and  12   b , respectively. 
     As shown in  FIG. 9 , an n-type cladding layer  222   a , an active layer  222   b , and a p-type cladding layer  222   c  are successively stacked on prescribed regions of an upper surface of a wafer-state n-type GaAs substrate  220  by photolithography and low-pressure MOCVD, thereby forming infrared semiconductor laser device portions  222 . Thereafter, an n-type cladding layer  221   a , an active layer  221   b  and a p-type cladding layer  221   c  are successively stacked on regions, formed with no infrared semiconductor laser device portions  222 , of the upper surface of the wafer-state n-type GaAs substrate  220  so as not to be in contact with the infrared semiconductor laser device portions  222 , thereby forming red semiconductor laser device portions  221 . At this time, a plurality of grooves  220   a  are formed between the red and infrared semiconductor laser device portions  221  and  222 , and removed portions  50  which are portions constituting the semiconductor laser device  100  worked into chips are also simultaneously formed. The n-type GaAs substrate  220  is an example of the “first substrate” in the present invention, and the red and infrared semiconductor laser device portions  221  and  222  are each an “second semiconductor device layer” in the present invention. The “second semiconductor laser device substrate” of the present invention is constituted by the n-type GaAs substrate  220  and the red and infrared semiconductor laser device portions  221  and  222 . The removed portion  50  is an example of the “needless region” in the present invention. 
     The device division grooves  60   a  extending in the direction X are formed from the p-type cladding layers  211   c  and  222   c  sides of the red and infrared semiconductor laser device portions  221  and  222  by photolithography and etching. At this time, the device division grooves  60   a  are formed to reach not only the red and infrared semiconductor laser device portions  221  and  222  but an upper portion of the wafer-state n-type GaAs substrate  220 , and to have substantially the same depth of the plurality of grooves  220   a . The device division groove  60   a  is an example of the “third device division groove” in the present invention. 
     As shown in  FIG. 10 , prescribed regions of the p-type cladding layer  211   c  are removed by photolithography and etching, thereby extending the ridges  21   d  in the direction X, while prescribed regions of the p-type cladding layer  222   c  are removed, thereby extending the ridges  22   f  in the direction X. When the ridges  21   f  and  22   f  are formed, the prescribed regions of the p-type cladding layers  221   c  and  222   c  are simultaneously removed, whereby the recess portions  21   d  and  22   d  formed on the both sides of the ridges  21   f  and  22   f  are formed, and the planar portions  21   e  and  22   e  extending to the both sides of the recess portions  21   d  and  22   d  are formed. 
     An insulating layer  223  having a uniform thickness is formed on the upper surfaces of the p-type cladding layers  221   c  and  222   c  and the upper surface of the wafer-state n-type GaAs substrate  220  by plasma CVD. At this time, the insulating layer  223  are stacked also in the grooves  220   a  and the device division grooves  60   a  and the planar portions  23   a  are formed on the upper surfaces of the planar portions  21   e  and  22   e . The insulating layer  223  formed on the upper surfaces of the ridges  21   f  and  22   f  are removed by photolithography and etching. Thus, the plurality of planar portions  23   a  are located above (in a direction Z 3 ) the upper surfaces of the ridges  21   f  and  22   f.    
     A metal layer (not shown) is stacked on the upper surfaces of the plurality of ridges  21   f  and  22   f  and the upper surfaces of the prescribed regions of the insulating layer  223  to correspond to the shapes of the n-type GaAs substrates  20  of the semiconductor laser devices  100  worked into chips by photolithography and vacuum evaporation. 
     A thickness of the wafer-state n-type GaAs substrate  220  is reduced from a side (Z 4  side) opposite to the side formed with the red and infrared semiconductor laser device portions  221  and  222  by etching, so that the wafer-state n-type GaAs substrate  220  has a thickness of about 100 μm. 
     A metal layer (not shown) is stacked on a surface on the side (Z 4  side), opposite to the side formed with the red and infrared semiconductor laser device portions  221  and  222 , of the wafer-state n-type GaAs substrate  220  by vacuum evaporation. Then, thermal treatment is performed at a temperature of about 400° C. Thus, the metal layer on the upper surfaces of the plurality of ridges  21   f  and  22   f  are alloyed to form the p-side electrodes  24   a  and  24   b , and the metal layer on the surface of the wafer-state n-type GaAs substrate  220  on the Z 4  side is alloyed to form an n-side electrode  225 . Thus, the plurality of ridges  21   f  and the p-side electrodes  24   a  can be brought into ohmic contact with each other, and the plurality of ridges  22   f  and the p-side electrodes  24   b  can be brought into ohmic contact with each other. Further, the wafer-state n-type GaAs substrate  220  and the n-side electrode  225  can be brought into ohmic contact with each other. 
     In the manufacturing process according to the first embodiment, the plurality of fusion layers  26   a  and  26   b  formed on the surface of the wafer-state n-type GaN substrate  210  and the plurality of p-side electrodes  24   a  and  24   b  formed on the surface of the wafer-state n-type GaAs substrate  220  are bonded to each other, as shown in  FIG. 11 . At this time, the plurality of fusion layers  26   a  and  26   b  are melt by applying heat having at least about 200° C. and not more than about 350° C., and the plurality of pad electrodes  12   a  and  12   b  formed on the surface of the wafer-state n-type GaN substrate  210  and the plurality of p-side electrodes  24   a  and  24   b  are bonded to each other. At this time, the plurality of pad electrodes  12   a  and  12   b  and the plurality of p-side electrodes  24   a  and  24   b  are so bonded to each other that the device division grooves  60   a  are located on the plurality of pad electrodes  12   a  and  12   b . A lower surface (surface on the Z 2  side) of the wafer-state n-type GaN substrate  210  is polished, whereby the wafer-state n-type GaN substrate  210  has a thickness of about 100 μm. Thereafter, an n-side electrode  213  is formed on the lower surface of the wafer-state n-type GaN substrate  210  by vacuum evaporation. At this time, thermal treatment for forming the n-side electrode  213  is not performed. Thus, the wafer-state semiconductor laser device  200  is formed. 
     In the manufacturing process of the first embodiment, second cleavage guide grooves  40   b  are formed on Y-side both ends of a surface, formed with the n-side electrode  225  of the wafer-state n-type GaAs substrate  220  with a diamond point, as shown in  FIG. 12 . At this time, the second cleavage guide grooves  40   b  overlap on a surface (YZ plane) perpendicular to the wafer-state n-type GaN substrates  210  and the wafer-state n-type GaAs substrate  220  to correspond to the first cleavage guide grooves  40   a  formed on the wafer-state n-type GaN substrate  210 , and formed only on the both ends of the wafer-state n-type GaAs substrate  220  on the Y sides. In other words, the second cleavage guide grooves  40   b  are not formed on a region other than the both ends of the wafer-state n-type GaAs substrate  220  on the Y sides. The second cleavage guide groove  40   b  is an example of the “second groove” in the present invention. 
     In this state, an edged tool  70  is pressed from the lower surface (surface on the Z 2  side) side of the wafer-state n-type GaN substrate  210 , thereby cleaving the wafer-state semiconductor laser device  200 . Thus, the bar-shaped semiconductor laser device  300  is formed, and the pairs of cavity facets  11   j ,  21   g  and  22   g  (see  FIG. 5 ) are formed on both ends of blue-violet, red and infrared semiconductor laser device portions  311 ,  321  and  322  on the X sides, respectively, as shown in  FIG. 13 . The first cleavage guide grooves  40   a  partially remain on the both ends of a bar-shaped n-type GaN substrate  310  and the blue-violet semiconductor laser device portion  311  on the X sides, thereby forming step portions  10   a  and  11   e . At this time, the step portions  10   a  and  11   e  are formed on the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  to extend between the n-type GaN substrate  10  (blue-violet semiconductor laser  11 ) and the red or infrared semiconductor laser device portion  21  or  22 , respectively. The dielectric film  31  and dielectric multiplayer films  32  (see  FIG. 5 ) are formed on cleavage planes located on both ends of the bar-shaped semiconductor laser device  300  on the X sides by facet coating treatment in the manufacturing process. 
     As shown in  FIG. 14 , the device division grooves  60   b  are formed on an n-side electrode  325  side of a bar-shaped n-type GaAs substrate  320  to extend in the direction X with the diamond point, and the device division grooves  60   c  are formed on an n-side electrode  313  side of the bar-shaped n-type GaN substrate  310  to extend in the direction X. At this time, the two device division grooves  60   b  are formed on the two-wavelength semiconductor laser device portion  30  with respect to the one device division groove  60   c . The region including no red and infrared semiconductor laser device portions  321  and  322 , held between the two device division grooves  60   b  is the removed portion  50  of the two-wavelength semiconductor laser device portion  30  removed in device division (division into chips) described later. The device division grooves  60   b  is an example of the “second device division groove” in the present invention. 
     In this state, the edged tool  70  is pressed from a side (Z 2  side) formed with the n-side electrode  313  of the blue-violet semiconductor laser device portion  311  of the bar-shaped n-type GaN substrate  310 , thereby dividing the bar-shaped semiconductor laser device  300 . At this time, the removed portions  50  which are portions not bonded by the fusion layers  26   a  and  26   b  are simultaneously removed. Thus, the wire bonding portion  11   i  (see  FIG. 8 ) of the blue-violet semiconductor laser device portion  11  is exposed outside. The device division grooves  60   c  partially remain on the both ends of the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  on the Y sides, thereby forming the step portions  10   b  and  13   a  (see  FIG. 1 ), while the device division grooves  60   b  partially remain on the both ends of the n-type GaAs substrate  20  and the n-side electrode  25  on the Y sides, thereby forming the step portions  20   b  and  25   a  (see  FIG. 1 ). Thus, the semiconductor laser device  100  (see  FIG. 1 ) according to the first embodiment is formed. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, as hereinabove described, after the step of bonding the red and infrared semiconductor laser device portions  221  and  222  onto the blue-violet semiconductor laser device portion  211  formed with the first cleavage guide grooves  40   a , cleavage is performed along the first and second cleavage guide grooves  40   a  and  40   b  in order to form cleavage planes on the blue-violet semiconductor laser device portion  211  and the wafer-state n-type GaN substrate  210  as well as the red and infrared semiconductor laser device portions  221  and  222  and the wafer-state n-type GaAs substrate  220 , whereby the blue-violet semiconductor laser device portion  211  and the red and infrared semiconductor laser device portions  221  and  222  are simultaneously cleaved in a state where the red and infrared semiconductor laser device portions  221  and  222  are bonded onto the blue-violet semiconductor laser device portion  211 , and hence the cavity facets  11   j ,  21   g  and  22   g  consisting of the cleavage planes can be simultaneously formed on the blue-violet, red and infrared semiconductor laser device portions  211 ,  221  and  222 , respectively. Thus, the cavity facets,  11   j ,  21   g  and  22   g  of the blue-violet, red and infrared semiconductor laser device portions  211 ,  221  and  222  can be easily located on the same surface. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the blue-violet semiconductor laser device portion  211  provided with the first cleavage guide grooves  40   a  is bonded onto the red and infrared semiconductor laser device portions  221  and  222 , whereby the blue-violet semiconductor laser device portion  211  side which is the side provided with the first cleavage guide grooves  40   a  may not be pressed to be cleaved and hence the excellent plurality of cavity facets  11   j  can be formed on the blue-violet semiconductor laser device portion  211 , and the red and infrared semiconductor laser device portions  221  and  222  can be located on the blue-violet semiconductor laser device portions  211  and hence the light-emitting points of the blue-violet semiconductor laser device portion  211  and the light-emitting points of the red and infrared semiconductor laser device portions  221  and  222  can be brought close to each other. The first cleavage guide grooves  40   a  can allow easy cleavage also when the blue-violet semiconductor laser device portion  211  and the wafer-state n-type GaN substrate  210  have large thicknesses. Further, the blue-violet semiconductor laser device portion  211  and the wafer-state n-type GaN substrate  210  as well as the red and infrared semiconductor laser device portions  221  and  222  and the wafer-state n-type GaAs substrate  220  can be cleaved along the first and second cleavage guide grooves  40   a  and  40   b , and hence the wafer-state semiconductor laser device  200  can be more reliably cleaved as compared with a case where only the first cleavage guide grooves  40   a  are formed. Thus, the more excellent cavity facets  21   g  and  22   g  can be obtained not only on the blue-violet semiconductor laser device portion  211  also on the red and infrared semiconductor laser device portions  221  and  222 . 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the first cleavage guide grooves  40   a  are formed in the form of the broken lines on the region except the plurality of ridges  11   d  of the blue-violet semiconductor laser device portion  211  and the vicinity thereof in the step of forming the first cleavage guide grooves  40   a  in the blue-violet semiconductor laser device portion  211 , whereby the first cleavage guide grooves  40   a  are formed on positions separated from the regions of the plurality of ridges  11   d , which are light-emitting portions, of the blue-violet semiconductor laser device portion  211 , and the vicinity thereof, and hence the ridges  11   d  of the blue-violet semiconductor laser device portion  211  can be inhibited from being damaged also when the first cleavage guide grooves  40   a  are formed. The first cleavage guide grooves  40   a  can be formed to extend on an substantially overall area, except the plurality of ridges  11   d  of the blue-violet semiconductor laser device portion  211  and the vicinity thereof, and hence the wafer-state n-type GaN substrate  210  and the blue-violet semiconductor laser device portion  211  can be reliably cleaved. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the first cleavage guide grooves  40   a  are formed in a width direction (direction Y) of the device substantially perpendicular to an extensional direction (direction X) of the plurality of ridges  11   d  in the step of forming the first cleavage guide grooves  40   a  on the blue-violet semiconductor laser device portion  211 , whereby the blue-violet semiconductor laser device portion  211  and the red and infrared semiconductor laser device portions  221  and  222  are cleaved along the direction Y (width direction of the device) substantially perpendicular to the extensional direction of the ridges  11   d  by the first cleavage guide grooves  40   a , and hence the cavity facets  11   j ,  21   g  and  22   g  (see  FIG. 5 ) consisting of the cleavage planes substantially perpendicular to the ridges  11   d  (waveguides) can be easily formed. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the first cleavage guide grooves  40   a  are formed to have the depth reaching not only the blue-violet semiconductor laser device portion  211  but the upper portion of the wafer-state n-type GaN substrate  210 , whereby the thickness of the n-type GaN substrate  210  formed with no the first cleavage guide grooves  40   a  is further reduced (thinner) due to the first cleavage guide grooves  40   a  having the depth reaching the n-type GaN substrate  210  also when the wafer-state semiconductor laser device  200  is formed by the n-type GaN substrate  210  which is generally difficult to be cleaved, and hence the n-type GaN substrate  210  made of nitride-based semiconductor can be more easily cleaved. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the wafer-state blue-violet, red and infrared semiconductor laser device portion  211 ,  221  and  222  are simultaneously cleaved along the first and second cleavage guide grooves  40   a  and  40   b  in a state where the second cleavage guide grooves  40   b  are formed on positions, overlapped with the regions formed with the first cleavage guide grooves in plan view, of the n-type GaAs substrate  220  in step of forming the second cleavage guide grooves  40   b  on the wafer-state n-type GaAs substrate  220 , whereby the bonded wafers can be more reliably cleaved as compared with a case of cleaving only along the first cleavage guide grooves  40   a . Thus, more excellent cavity facets (cleavage planes) can be obtained not only on the blue-violet semiconductor laser device portion  211  but also on the red and infrared semiconductor laser device portions  221  and  222 . 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the second cleavage guide grooves  40   b  are formed on the surface on the side opposite to the side bonded onto the blue-violet semiconductor laser device portion  211  (on the Z 1  side shown in  FIG. 12 ) to correspond to the first cleavage guide grooves  40   a  in the step of forming the second cleavage guide grooves  40   b  on the wafer-state n-type GaAs substrate  220 , whereby positions of the second cleavage guide grooves  40   b  can be easily recognized from outside, and hence pressing force for simultaneously cleaving the wafer-state blue-violet, red and infrared semiconductor laser device portions  211 ,  221  and  222  with the edged tool  70  can be suitably applied while confirming the positions of the second cleavage guide grooves  40   b.    
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the second cleavage guide grooves  40   b  are formed in the vicinity of the Y-side both ends of the surface, on the side opposite to the side formed with the red and infrared semiconductor laser device portions  221  and  222 , of the wafer-state n-type GaAs substrate  220  in the step of forming the second cleavage guide grooves  40   b  on the wafer-state n-type GaAs substrate  220 , whereby the wafer-state n-type GaAs substrate  220  and the red and infrared semiconductor laser device portions  221  and  222  can be easily cleaved, and the cavity facets  11   j ,  21   g , and  22   g  of the blue-violet, red and infrared semiconductor laser device portions  211 ,  221  and  222  can be inhibited from being deviated in a cavity direction (direction X) due to deviation of the first and second cleavage guide grooves  40   a  and  40   b  when the second cleavage guide grooves  40   b  are formed on an overall area of the wafer-state n-type GaAs substrate  220 . 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the partial wafer (removed portions  50  of the two-wavelength semiconductor device portion  30  shown in  FIG. 14 ) on the bonded red and infrared semiconductor laser device portions  221  and  222  side is removed after the step of cleaving the wafer-state blue-violet, red and infrared semiconductor laser device portions  211 ,  221  and  222 , whereby device division can be preformed only on the portion of the blue-violet semiconductor laser device portion  211  with no removed portions  50  along the cavity direction (direction X) when the wafer after removing the removed portions  50  is divided into chips in subsequent steps, and hence a chip of the semiconductor laser device  100  can be easily obtained. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, after the step of cleaving the wafer-state blue-violet, red and infrared semiconductor laser device portion  211 ,  221  and  222 , protective films made of dielectric multilayer films are formed on the cleavage planes (cavity facets  11   j ,  21   g  and  22   g ) in advance of the step of removing the removed portions  50 , whereby the wafer in which the blue-violet semiconductor laser device portion  211  and the red and infrared semiconductor laser device portions  221  and  222  are bonded to each other is formed with protective films (insulating films) on the cavity facets  11   j ,  21   g  and  22   g  (cleavage planes) in a state where the wafer has a substantially uniform thickness. Thus, a disadvantage that the exposed pad electrodes  12   a  and  12   b  are insulated by the protective films extending toward and covering the surfaces of the exposed pad electrodes  12   a  and  12   b  (see  FIG. 5 ) does not occur dissimilarly to a case where the removed portions  50  are removed to expose the pad electrodes  12   a  and  12   b  on the blue-violet semiconductor laser device portion  211  before forming the protective films and the protective films are thereafter formed, for example, and hence the wires bonded after division into chips and the pad electrodes  12   a  and  12   b  can be reliably electrically connected (wire-bonded). 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, when the wafer where the blue-violet semiconductor laser device portion  211  and the red and infrared semiconductor laser device portions  221  and  222  are bonded is divided into chips, the removed portions  50  are simultaneously removed, whereby the removed portions  50  are simultaneously removed when dividing the wafer into chips, and hence the manufacturing process can be simplified. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the device division grooves  60   c  are formed on the surface of the bar-shaped n-type GaN substrate  310  in advance of the step of dividing the wafer into chips, and the device division grooves  60   b  for removing the removed portions  50  are formed on the surface of the bar-shaped n-type GaAs substrate  320 , whereby the n-type GaAs substrate  320  can be also divided on the positions formed with the device division grooves  60   b  into regions remaining on the chips and regions removed from the chips (removed portions  50 ) in response to division of the n-type GaN substrate  310  on the portions of the device division grooves  60   c  when dividing the bar. Thus, the removed portions  50  can be easily removed while the wafer is simultaneously divided into chips. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the device division grooves  60   a  are formed on the surface on the side opposite to the side formed with the device division grooves  60   b  to correspond to the device division grooves  60   b  in advance of bonding the red semiconductor laser device portions  221  (infrared semiconductor laser device portions  222 ) onto the wafer-state blue-violet semiconductor laser device portion  211 , whereby in the bar-shaped n-type GaAs substrate  320 , the wafer (substrate) is easily partially divided not only by the device division grooves  60   b  but the device division grooves  60   a , and hence the removed portions  50  can be easily removed. 
     In the manufacturing process of the semiconductor laser device according to the first embodiment, the pad electrodes  12   a  and  12   b  are exposed by removing the removed portions  50 , whereby the wires can be easily bonded onto the portions of the pad electrodes  12   a  and  12   b  exposed on the surface of the bar-shaped blue-violet semiconductor laser device portion  211  by removing the removed portions  50 . 
     Modification of First Embodiment 
     A modification of the first embodiment will be described with reference to  FIGS. 15 to 17 . In this modification of the first embodiment, second cleavage guide grooves  40   c  formed on an n-side electrode  225  side of an n-type GaAs substrate  220  are formed in the form of broken lines along a direction Y, dissimilarly to the aforementioned manufacturing process of the first embodiment. 
     In other words, in the manufacturing process in the modification of the first embodiment, the broken-line shaped second cleavage guide grooves  40   c  in which groove portions having a length of about 200 μm are formed at intervals of about 200 μm along the direction Y are formed on a surface, formed with the n-side electrode  225 , of the wafer-state n-type GaAs substrate  220  with a diamond point, as shown in  FIG. 15 . At this time, the second cleavage guide grooves  40   c  are formed to overlap on a surface (YZ plane) perpendicular to the n-type GaN substrate  210  and the n-type GaAs substrate  220  to correspond to the first cleavage guide grooves  40   a  formed on the n-type GaN substrate  210 . 
     Each of the broken-line shaped second cleavage guide grooves  40   c  is formed on a region corresponding to a removed portion  50  removed in later steps. The second cleavage guide groove  40   c  is an example of the “second groove” in the present invention. 
     In this state, an edged tool  70  is pressed from a lower surface (surface on a Z 2  side) side of the wafer-state n-type GaN substrate  210 , thereby cleaving a wafer-state semiconductor laser device  200 , as shown in  FIG. 16 . At this time, the wafer is cleaved along the broken-line shaped second cleavage guide grooves  40   c.    
     As shown in  FIG. 17 , device division grooves  60   b  are formed on an n-side electrode  325  side of a bar-shaped n-type GaAs substrate  320  to extend in a direction X and device division grooves  60   c  are formed on an n-side electrode  313  side of a bar-shaped n-type GaN substrate  310  to extend in the direction X, similarly to the aforementioned manufacturing process of the first embodiment. 
     In this state, the edged tool  70  is pressed from a side (Z 2  side) formed with the n-side electrode  313  of a blue-violet semiconductor laser device portion  311  of the bar-shaped n-type GaN substrate  310 , thereby dividing a bar-shaped semiconductor laser device  300 . At this time, the removed portions  50  which are portions not bonded by fusion layers  26   a  and  26   b  are removed. 
     In the manufacturing process of the semiconductor laser device according to the modification of the first embodiment, as hereinabove described, the second cleavage guide grooves  40   c  are formed in the form of the broken lines along the direction Y in the step of forming the second cleavage guide grooves  40   c  on the wafer-state n-type GaAs substrate  220 , whereby the second cleavage guide grooves  40   c  can be formed in the form of broken lines on a substantially overall area of the surface formed with the n-side electrode  225  of the wafer-state n-type GaAs substrate  220  along an extensional direction of the first cleavage guide grooves  40   a . Therefore, regions formed with the second cleavage guide grooves  40   c  are increased and hence the n-type GaAs substrate  220  can be more easily cleaved. 
     In the manufacturing process of the semiconductor laser device according to the modification of the first embodiment, the second cleavage guide grooves  40   c  formed on the n-type GaAs substrate  220  are formed on positions corresponding to the removed portions  50  of the n-type GaAs substrate  220 , whereby only cavity facets  21   g  and  22   g  consisting of cleavage planes employing ends of the broken-line shaped second cleavage guide grooves  40   c  removed together with the removed portions  50  as starting points of cracks can be easily formed on regions remaining on a chip of the n-type GaAs substrate  220 , dissimilarly to a case where the second cleavage guide grooves  40   c  remain the regions remaining on the chip of the n-type GaAs substrate  220 . 
     Second Embodiment 
     Referring to  FIG. 18 , in a second embodiment, an infrared semiconductor laser device portion  22  formed on an n-type GaAs substrate  20  is bonded onto an upper portion of a ridge  11   d  of a blue-violet semiconductor laser device portion  11  formed on an n-type GaN substrate  10  of a semiconductor laser device  400 , dissimilarly to the aforementioned first embodiment. 
     In the semiconductor laser device  400  formed through a manufacturing method according to the second embodiment of the present invention, on an upper surface of a second insulating layer  11   h , a pad electrode  412   b  is formed on a position corresponding to the upper portion of the ridge  11   d  of the blue-violet semiconductor laser device portion  11  provided on the n-type GaN substrate  10 , as shown in  FIG. 18 . The infrared semiconductor laser device portion  22  provided on an n-type GaAs substrate  20  is bonded onto an upper surface of the pad electrode  412   b  through a fusion layer  426   b . Thus, an interval between a light-emitting point of the blue-violet semiconductor laser device portion  11  and a light-emitting point of the infrared semiconductor laser device portion  22  can be reduced. The remaining structure, manufacturing process and effects of the semiconductor laser device  400  are similar to those of the aforementioned first embodiment. 
     Third Embodiment 
     Referring to  FIG. 19 , in a third embodiment, an n-type GaAs substrate  20  is not located on an upper portion of a ridge  11   d  of a blue-violet semiconductor laser device portion  11  formed on an n-type GaN substrate  10  of a semiconductor laser device  500 , dissimilarly to the aforementioned first embodiment. 
     In the semiconductor laser device  500  formed through a manufacturing method according to the third embodiment of the present invention, the ridge  11   d  of the blue-violet semiconductor laser device portion  11  provided on the n-type GaN substrate  10  is formed on a Y 2  side, and pad electrodes  512   a  and  512   b  are so formed on an upper surface of a second insulating layer  11   h  on a Y 1  side of the ridge  11   d  that the red and infrared semiconductor laser device portions  21  and  22  provided on the n-type GaAs substrate  20  can be bonded, respectively, as shown in  FIG. 19 . The red and infrared semiconductor laser device portions  21  and  22  provided on the n-type GaAs substrate  20  are bonded onto an upper surfaces of the pad electrodes  512   a  and  512   b  through fusion layers  26   a  and  26   b , respectively. In other words, the n-type GaAs substrate  20  is formed not to be located on the upper portion of the ridge  11   d  of the blue-violet semiconductor laser device portion  11 . Thus, heat can be easily radiated on the blue-violet semiconductor laser device portion  11 . The remaining structure, manufacturing process and effects of the semiconductor laser device  500  are similar to those of the aforementioned first embodiment. 
     Fourth Embodiment 
     Referring to  FIG. 20 , in a fourth embodiment, a semiconductor laser device  600  is a two-wavelength semiconductor laser device in which a red semiconductor laser device portion  21  formed on an n-type GaAs substrate  620  is bonded onto an upper portion of a ridge  11   d  of a blue-violet semiconductor laser device portion  11  formed on an n-type GaN substrate  10 , dissimilarly to the aforementioned second embodiment. 
     In the semiconductor laser device  600  formed through a manufacturing method of the fourth embodiment of the present invention, on an upper surface of a second insulating layer  11   h , a pad electrode  612   b  is formed on a position corresponding to the upper portion of the ridge  11   d  of the blue-violet semiconductor laser device portion  11  provided on the n-type GaN substrate  10 , as shown in  FIG. 20 . The red semiconductor laser device portion  21  provided on an n-type GaAs substrate  620  is bonded onto an upper surface of the pad electrode  612   a  through a fusion layer  626   a . No infrared semiconductor laser device portion  22  in the second embodiment is formed on the n-type GaAs substrate  620 . Thus, an interval between a light-emitting point of the blue-violet semiconductor laser device portion  11  and a light-emitting point of the infrared semiconductor laser device portion  22  can be reduced, and size of a chip of the semiconductor laser device  600  can be reduced. The remaining structure, manufacturing process and effects of the semiconductor laser device  600  are similar to those of the aforementioned second embodiment. 
     Fifth Embodiment 
     Referring to  FIG. 21 , in a fifth embodiment, a semiconductor laser device  700  is a two-wavelength semiconductor laser device in which an n-type GaAs substrate  720  and a red semiconductor laser device portion  21  are not located on an upper portion of a ridge  11   d  of a blue-violet semiconductor laser device portion  11  formed on an n-type GaN substrate  10 , dissimilarly to the aforementioned third embodiment. 
     In the semiconductor laser device  700  formed through a manufacturing method of the fifth embodiment of the present invention, the ridge  11   d  of the blue-violet semiconductor laser device portion  11  provided on the n-type GaN substrate  10  is formed on a Y 2  side, and a pad electrode  712   a  is so formed on an upper surface of a second insulating layer  11   h  on a Y 1  side of the ridge  11   d  that the red semiconductor laser device portion  21  provided on the n-type GaAs substrate  720  can be bonded, as shown in  FIG. 21 . The red semiconductor laser device portion  21  provided on the n-type GaAs substrate  720  is bonded onto an upper surface of the pad electrode  712   a  through a fusion layer  26   a . In other words, the n-type GaAs substrate  720  and the red semiconductor laser device portion  21  formed on the n-type GaAs substrate  720  are not located on the upper portion of the ridge  11   d  of the blue-violet semiconductor laser device portion  11 . Thus, heat can be easily radiated on the blue-violet semiconductor laser device portion  11 , and size of a chip of the semiconductor laser device  700  can be reduced. The remaining structure, manufacturing process and effects of the semiconductor laser device  700  are similar to those of the aforementioned third embodiment. 
     Sixth Embodiment 
     Referring to  FIG. 22 , in a sixth embodiment, step portions  810   a  and  811   e  formed on an n-type GaN substrate  10  and a blue-violet semiconductor laser device portion  11  of a semiconductor laser device  800 , respectively, are not located between the n-type GaN substrate  10  (blue-violet semiconductor laser  11 ) and a red or infrared semiconductor laser device portion  21  or  22 , dissimilarly to the aforementioned first embodiment. 
     In the semiconductor laser device  800  formed through a manufacturing method of the sixth embodiment of the present invention, the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  are formed with the step portions  810   a  and  811   e  on both ends of the n-type GaAs substrate  10  and the blue-violet semiconductor laser device portion  11  on the X and Y sides, respectively, as shown in  FIG. 22 . In other words, the step portions  810   a  and  811   e  are formed on the n-type GaN substrate  10  and the blue-violet semiconductor laser device portion  11  so as not to be located between the n-type GaN substrate  10  (blue-violet semiconductor laser  11 ) and the red or infrared semiconductor laser device portion  21  or  22 . Thus, in the manufacturing process, a wafer-state semiconductor laser device can be inhibited from accidentally cracking from first cleavage guide grooves. The remaining structure, manufacturing process and effects of the semiconductor laser device  800  are similar to those of the aforementioned first embodiment. 
     Seventh Embodiment 
     An optical pickup  900  according to a seventh embodiment of the present invention will be described with reference to  FIG. 5  and  FIGS. 23 to 25 . The optical pickup  900  is an example of the “light apparatus” in the present invention. 
     The optical pickup  900  according to the seventh embodiment of the present invention comprises a semiconductor laser apparatus  910  mounted with the semiconductor laser device  100  (see  FIG. 25 ) according to the aforementioned first embodiment, an optical system  920  adjusting a laser beam emitted from the semiconductor laser apparatus  910 , and a light detection portion  930  receiving the laser beam, as shown in  FIG. 23 . 
     The semiconductor laser apparatus  910  has a base  911  made of a conductive material, a cap  912  arranged on a front surface of the base  911 , leads  913 ,  914 ,  915  and  916  mounted on a rear surface of the base  911 , as shown in  FIGS. 24 and 25 . The header  911   a  (see  FIG. 25 ) is integrally formed with the base  911  on the front surface of the base  911 . The semiconductor laser device  100  is arranged on an upper surface of the header  911   a , and a submount (substrate)  101  (see  FIG. 25 ) made of a conductive material such as Cu and the header  911   a  are fixed by a bonding layer  917  (see  FIG. 25 ) made of Au—Sn solder. An optical window  912   a  (see  FIG. 24 ) transmitting a laser beam emitted from the semiconductor laser device  100  is mounted on a front surface of the cap  912 , and the semiconductor laser device  100  inside the base  911  covered with the cap  912  is sealed by the cap  912 . 
     As shown in  FIG. 25 , the leads  913  to  915  pass through the base  911  and fixed to be electrically insulated from each other through insulating members  918 . The lead  913  is electrically connected to a pad electrode  12   a  through a wire  901 , and the lead  915  is electrically connected to a pad electrode  12   b  through a wire  901 . The lead  914  is electrically connected to a wire bonding portion  11   i  (see  FIG. 5  for a planar position) of a p-side electrode  11   g  through a wire  903 . An n-side electrode  25   a  and a connecting electrode  102  on the submount  101  are electrically connected through a wire  904 . The lead  916  is integrally formed with the base  911 . Thus, the lead  916  and an n-side electrode  13  of the blue-violet semiconductor laser device portion  11  as well as the lead  916  and the n-side electrode  25   a  of the red semiconductor laser device portion  21  (infrared semiconductor laser device portion  22 ) are electrically connected, and cathode common connection of the blue-violet semiconductor laser device portion  11  and a red semiconductor laser device portion  21  (infrared semiconductor laser device portion  22 ) is achieved. 
     The optical system  920  has a polarizing beam splitter (PBS)  921 , a collimator lens  922 , beam expander  923 , a λ/4 plate  924 , an objective lens  925 , a cylindrical lens  926  and an optical axis correction device  927 , as shown in  FIG. 23 . 
     The PBS  921  totally transmits the laser beam emitted from the semiconductor laser device  910  and totally reflects the laser beam returned from an optical disc  980 . The collimator lens  922  converts the laser beam from the semiconductor laser device  100  transmitting through the PBS  921  to parallel light. The beam expander  923  includes a concave lens, a convex lens and an actuator (not shown). The actuator has a function of correcting a state of wavefront of the laser beam emitted from the semiconductor laser apparatus  910  by changing a distance of the concave lens and the convex lens in response to a servo signal from the servo circuit described later. 
     The λ/4 plate  924  converts a linearly-polarized laser beam converted to substantially parallel light by the collimator lens  922  to circularly-polarized light. The λ/4 plate  924  converts the circularly-polarized laser beam returned from the optical disc  935  to linearly-polarized light. A direction of polarization of linearly-polarized light in this case is perpendicular to a direction of linear polarization of the laser beam emitted from the semiconductor laser apparatus  910 . Thus, the laser beam returned from the optical disc  935  is totally reflected by the PBS  921 . The objective lens  925  converges the laser beam transmitted through the λ/4 plate  924  on a surface (recording layer) of the optical disc  935 . The objective lens  925  is movable in a focus direction, a tracking direction and a tilt direction in response to a servo signal (a tracking servo signal, a focus servo signal and a tilt servo signal) from the servo circuit described later by an objective lens actuator (not shown). 
     The cylindrical lens  926 , optical axis correction device  927  and the light detection portion  930  are arranged along an optical axis of the laser beam totally reflected by the PBS  921 . The cylindrical lens  926  gives astigmatic action to an incident laser beam. The optical axis correction device  927  is formed by diffraction grating and so arranged that a spot of zero-order diffracted light of each of blue-violet, red and infrared laser beams transmitted through the cylindrical lens  926  coincides on a detection region of the light detection portion  930  described later. 
     The light detection portion  930  outputs a playback signal on the basis of intensity distribution of a received laser beam. The light detection portion  930  has a prescribed patterned detection region to obtain the playback signal as well as a focus error signal, a tracking error signal and a tilt error signal. Thus, the optical pickup  900  comprising the semiconductor laser apparatus  910  is formed. 
     In this optical pickup  900 , the semiconductor laser apparatus  910  is so formed that blue-violet, red and infrared laser beams independently emit from the blue-violet, red and infrared semiconductor laser device portions  11 ,  21  and  22  by independently applying voltages between the lead  916  and the leads  913  to  915 , respectively. As hereinabove described, the laser beams emitted from the semiconductor laser apparatus  910  are adjusted by the PBS  921 , the collimator lens  922 , the beam expander  923 , the λ/4 plate  924 , the objective lens  925 , cylindrical lens  926  and the optical axis correction device  927 , and thereafter irradiated on the detection region of the light detection portion  930 . 
     When data recorded in the optical disc  935  is playback, the laser beams are applied to the recording layer of the optical disc  935  and the playback signal output from the light detection portion  930  can be obtained while controlling respective laser power emitted from the blue-violet, red and infrared semiconductor laser device portions  11 ,  21  and  22  to be constant. The actuator of the beam expander  923  and the objective lens actuator driving the objective lens  925  can be feedback-controlled by the focus error signal, the tracking error signal and the tilt error signal simultaneously output. 
     When data is recorded in the optical disc  935 , the laser beams are applied to the optical disc  935  while controlling laser power emitted from the blue-violet semiconductor laser device portion  11  and the red semiconductor laser device portion  21  (infrared semiconductor laser device portion  22 ) on the basis of data to be recorded. Thus, the data can be recorded in the recording layer of the optical disc  935 . Similarly to the above, the actuator of the beam expander  923  and the objective lens actuator driving the objective lens  925  can be feedback-controlled by the focus error signal, the tracking error signal and the tilt error signal output from the light detection portion  930 . 
     Thus, record in the optical disc  935  and playback can be performed with the optical pickup  900  comprising the semiconductor laser apparatus  910 . 
     In the optical pickup  900  of the seventh embodiment, the semiconductor laser device  100  is mounted in the semiconductor laser apparatus  910 , and hence the optical pickup  900  comprising the semiconductor laser device  100  in which cavity facets  11   j ,  21   g , and  22   g  (see  FIG. 5 ) of blue-violet, red and infrared semiconductor laser device portions  11 ,  21  and  22  are easily located on the same surface can be obtained. 
     Eight Embodiment 
     An optical disc apparatus  5000  according to an eight embodiment of the present invention will be described with reference to  FIGS. 5 ,  23  and  26 . The optical disc apparatus  5000  is an example of the “light apparatus” in the present invention. 
     The optical disc apparatus  5000  according to the eight embodiment of the present invention comprises the optical pickup  900  according to the aforementioned seventh embodiment, a controller  5001 , a laser operating circuit  5002 , a signal generation circuit  5003 , a servo circuit  5004  and a disc driving motor  5005 , as shown in  FIG. 26 . 
     Recorded data S 1  generated on the basis of data to be recorded in the optical disc  935  is inputted in the controller  5001 . The controller  5001  outputs a signal S 2  to the laser operating circuit  5002  and outputs a signal S 7  to the servo circuit  5004  in response to the record data S 1  and a signal S 5  from the signal generation circuit  5003  described later. The controller  5001  outputs playback data S 10  on the basis of the signal S 5 , as described later. The laser operating circuit  5002  outputs a signal S 3  controlling laser power emitted from the semiconductor laser apparatus  910  in the optical pickup  900  in response to the aforementioned signal S 2 . In other words, the semiconductor laser apparatus  910  is formed to be driven by the controller  5001  and the laser operating circuit  5002 . 
     In the optical pickup  900 , a laser beam controlled in response to the aforementioned signal S 3  is applied to the optical disc  935 , as show in  FIG. 26 . A signal S 4  is output from the light detection portion  930  in the optical pickup  900  to the signal generation circuit  5003 . The optical system  920  (the actuator of the beam expander  923  and the objective lens actuator driving the objective lens  925 ) in the optical pickup  900  is controlled by a servo signal S 8  from the servo circuit  5004  described later. The signal generation circuit  5003  performs amplification and arithmetic processing for the signal S 4  output from the optical pickup  900 , to output the first output signal S 5  including a playback signal to the controller  5001  and to output a second output signal S 6  performing the aforementioned feed-back control of the optical pickup  900  and rotational control, described later, of the optical disc  935  to the servo circuit  5004 . 
     As shown in  FIG. 26 , the servo circuit  5004  outputs the servo signal S 8  controlling the optical system  920  in the optical pickup  900  and a motor servo signal S 9  controlling the disc driving motor  5005  in response to the second output signal S 6  and the signal S 7  from the signal generation circuit  5003  and the controller  5001 . The disc driving motor  5005  controls a rotational speed of the optical disc  935  in response to the motor servo signal S 9 . 
     When data recorded in the optical disc  935  is playback, a laser beam having a wavelength to be applied is first selected by means identifying types (CD, DVD, BD, etc.) of the optical disc  935  which is not described here. Then, the signal S 2  is so output from the controller  5001  to the laser operating circuit  5002  that an intensity of the laser beam having the wavelength to be emitted from the semiconductor laser apparatus  910  in the optical pickup  900  is constant. Further, the signal S 4  including a playback signal is output from the light detection portion  930  to the signal generation circuit  5003  by functioning the semiconductor laser apparatus  910 , the optical system  920  and the light detection portion  930  of the optical pickup  900  described above, and the signal generation circuit  5003  outputs the signal S 5  including the playback signal to the controller  5001 . The controller  5001  processes the signal S 5 , so that the playback signal recorded in the optical disc  935  is extracted and output as the reproduction data S 10 . Information such as images and sound recorded in the optical disc  935  can be output to a monitor, a speaker and the like with this playback data S 10 , for example. Feed-back control of each portion is performed on the basis of the signal S 4  from the light detection portion  930 . 
     When data is recorded in the optical disc  935 , the laser beam having the wavelength to be applied is selected by the means identifying types (CD, DVD, BD, etc.) of the optical disc  935 , similarly to the above. Then, the signal S 2  is output from the controller  5001  to the laser operating circuit  5002  in response to the record data S 1  responsive to recorded data. Further, data is recorded in the optical disc  935  by functioning the semiconductor laser apparatus  910 , the optical system  920  and the light detection portion  930  of the optical pickup  900  described above, and feed-back control of each portion is performed on the basis of the signal S 4  from the light detection portion  930 . 
     Thus, record in the optical disc  935  and playback can be performed with the optical disc apparatus  5000 . 
     In the optical disc apparatus  5000  according to the eight embodiment, the semiconductor laser device  100  (see  FIG. 23 ) is mounted in the semiconductor laser apparatus  910  (see  FIG. 23 ), and hence the optical disc apparatus  5000  comprising the semiconductor laser device  100  in which cavity facets  11   j ,  21   g , and  22   g  (see  FIG. 5 ) of blue-violet, red and infrared semiconductor laser device portions  11 ,  21  and  22  are easily located on the same surface can be obtained. 
     Ninth Embodiment 
     A structure of a projector  6000  according to a ninth embodiment of the present invention will be described with reference to  FIGS. 1 ,  27  and  28 . In the projector  6000 , each of semiconductor laser devices constituting a semiconductor laser apparatus  940  is substantially simultaneously turned on. The projector  6000  is an example of the “light apparatus” in the present invention. 
     The projector  6000  according to the ninth embodiment of the present invention comprises the semiconductor laser apparatus  940 , an optical system  6020  consisting of a plurality of optical components and a control portion  6050  controlling the semiconductor laser apparatus  940  and the optical system  6020 , as shown in  FIG. 28 . Thus, laser beams emitted from the semiconductor laser apparatus  940  are modulated by the optical system  6020  and thereafter projected on an external screen  6090  or the like. 
     As shown in  FIG. 27 , the semiconductor laser apparatus  940  comprises an RGB three-wavelength semiconductor laser device  980  formed by bonding a red semiconductor laser device portion  950  having a lasing wavelength of about 655 nm of red (R) onto a two-wavelength semiconductor laser device  970  monolithically formed with a green semiconductor laser device portion  960  having a lasing wavelength of about 530 nm of green (G) and a blue semiconductor laser device portion  965  having a lasing wavelength of about 480 nm of blue (B), and capable of emitting laser beams of three-wavelengths of RGB. 
     The RGB three-wavelength semiconductor laser device  980  comprises the red semiconductor laser device portion  950  formed on an upper surface of an n-type GaAs substrate  20  instead of the blue-violet semiconductor laser device portion  11 , and the two-wavelength semiconductor laser device portion  970  monolithically formed with the green semiconductor laser device portion  960  and the blue semiconductor laser device portion  965  on a lower surface of an n-type GaN substrate  10  instead of the two-wavelength semiconductor laser device portion  30  monolithically formed with the red and infrared semiconductor laser device portions  21  and  22 , with reference to the semiconductor laser device  100  of the first embodiment shown in  FIG. 1 . The remaining structure and manufacturing process of the RGB three-wavelength semiconductor laser device  980  are similar to those of the semiconductor laser device  100  of the aforementioned first embodiment. 
     In the RGB three-wavelength semiconductor laser device  980 , an n-side electrode  953  is electrically connected and fixed on an upper surface of a submount  101  through a bonding layer  917  made of Au—Sn solder or the like. 
     The “first semiconductor laser device” in the present invention is constituted by the n-type GaAs substrate  20  and the red semiconductor laser device portion  950 , and the “second semiconductor laser device” in the present invention is constituted by the n-type GaN substrate  10  and the two-wavelength semiconductor laser device portion  970  consisting of the green semiconductor laser device portion  960  and the blue semiconductor laser device portion  965 . 
     A lead  913  is electrically connected to a pad electrode  952   a  conducting with a p-type semiconductor layer of the green semiconductor laser device portion  960  through a wire  981 , and a lead  915  is electrically connected to a pad electrode  952   b  conducting with a p-type semiconductor layer of the blue semiconductor laser device portion  965  through a wire  982 . A lead  914  is electrically connected to a p-side electrode  951   g  (wire bonding portion  951   i ) of the red semiconductor laser device portion  950  through a wire  983 . An n-side electrode  975   a  of the two-wavelength semiconductor laser device  970  and a connecting electrode  102  on the submount  101  are electrically connected through a wire  984 . Thus, a lead  916  and the n-side electrode  953  of the red semiconductor laser device portion  950  as well as the lead  916  and the n-side electrode  975   a  of the two-wavelength semiconductor laser device  970  are electrically connected, and cathode common connection of the red semiconductor laser device portion  950  and the two-wavelength semiconductor laser device  970  is achieved. The pad electrodes  952   a  and  952   b  are each an example of the “electrode layer” in the present invention. 
     In the optical system  6020 , the laser beams emitted from the semiconductor laser apparatus  940  are converted to parallel beams having prescribed beam diameters by a dispersion angle control lens  6022  consisting of a concave lens and a convex lens, and thereafter introduced into a fly-eye integrator  6023 , as shown in  FIG. 28 . The fly-eye integrator  6023  is so formed that two fly-eye lenses consisting of fly-eye lens groups face each other, and provides a lens function to the beams introduced from the dispersion angle control lens  6022  so that light quantity distributions in incidence upon liquid crystal panels  6029 ,  6033  and  6040  are uniform. In other words, the beams transmitted through the fly-eye integrator  6023  are so adjusted that the same can be incident upon the liquid crystal panels  6029 ,  6033  and  6040  with spreads of aspect ratios (16:9, for example) corresponding to the sizes of the liquid crystal panels  6029 ,  6033  and  6040 . 
     The beams transmitted through the fly-eye integrator  6023  are condensed by a condenser lens  6024 . In the beams transmitted through the condenser lens  6024 , only the red beam is reflected by a dichroic mirror  6025 , while the green and blue beams are transmitted through the dichroic mirror  6025 . 
     The red beam is parallelized by a lens  6027  through a mirror  6026 , and thereafter incident upon the liquid crystal panel  6029  through an incidence-side polarizing plate  6028 . The liquid crystal panel  6029  is driven in response to a red image signal (R image signal), thereby modulating the red beam. 
     In the beams transmitted through a dichroic mirror  6025 , only the green beam is reflected by the dichroic mirror  6030 , while the blue beam is transmitted through the dichroic mirror  6030 . 
     The green beam is parallelized by a lens  6031 , and thereafter incident upon the liquid crystal panel  6033  through an incidence-side polarizing plate  6032 . The liquid crystal panel  6033  is driven in response to a green image signal (G image signal), thereby modulating the green beam. 
     The blue beam transmitted through the dichroic mirror  6030  passes through a lens  6034 , a mirror  6035 , a lens  6036  and a mirror  6037 , is parallelized by a lens  6038 , and thereafter incident upon the liquid crystal panel  6040  through an incidence-side polarizing plate  6039 . The liquid crystal panel  6040  is driven in response to a blue image signal (B image signal), thereby modulating the blue beam. 
     Thereafter the red, green and blue beams modulated by the liquid crystal panels  6029 ,  6033  and  6040  are synthesized by a dichroic prism  6041 , and thereafter introduced into a projection lens  6043  through an emission-side polarizing plate  6042 . The projection lens  6043  stores a lens group for imaging projected light on a projected surface (screen  6090 ) and an actuator for adjusting the zoom and the focus of the projected image by partially displacing the lens group in an optical axis direction. 
     In the projector  6000 , the control portion  6050  controls to supply stationary voltages as an R signal related to driving of the red semiconductor laser device portion  950 , a G signal related to driving of the green semiconductor laser device portion  960  and a B signal related to driving of the blue semiconductor laser device portion  965  to the respective laser devices of the semiconductor laser apparatus  940 . Thus, the red, green and blue semiconductor laser device portions  950 ,  960  and  965  of the semiconductor laser apparatus  940  are substantially simultaneously derived. The control portion  6050  is formed to control the intensities of the beams emitted from the red, green and blue semiconductor laser device portions  950 ,  960  and  965  of the semiconductor laser apparatus  940 , thereby controlling the hue, brightness etc. of pixels projected on the screen  6090 . Thus, the control portion  6050  projects a desired image on the screen  6090 . 
     The projector  6000  loaded with the semiconductor laser apparatus  940  according to the first embodiment of the present invention is constituted in the aforementioned manner. 
     Tenth Embodiment 
     A structure of a projector  6500  according to a tenth embodiment of the present invention will be described with reference to  FIGS. 27 ,  29  and  30 . In the projector  6500 , each of semiconductor laser devices constituting a semiconductor laser apparatus  940  is turned on in a time-series manner. The projector  6500  is an example of the “light apparatus” in the present invention. 
     The projector  6500  according to the tenth embodiment of the present invention comprises the semiconductor laser apparatus  940  employed in the aforementioned ninth embodiment, an optical system  6520 , and a control portion  6550  controlling the semiconductor laser apparatus  940  and the optical system  6520 , as shown in  FIG. 29 . Thus, beams emitted from the semiconductor laser apparatus  940  are modulated by the optical system  6520  and thereafter projected on a screen  6590  or the like. 
     In the optical system  6520 , the beams emitted from the semiconductor laser apparatus  940  are converted to parallel beams by a lens  6522 , and thereafter introduced into a light pipe  6524 . 
     The light pipe  6524  has a specular inner surface, and the laser beams are repeatedly reflected by the inner surface of the light pipe  6524  to travel in the light pipe  6524 . At this time, intensity distributions of the beams of respective colors emitted from the light pipe  6524  are uniformized due to multiple reflection in the light pipe  6524 . The beams emitted from the light pipe  6524  are introduced into a digital micromirror device (DMD)  6526  through a relay optical system  6525 . 
     The DMD  6526  consists of a group of small mirrors arranged in the form of a matrix. The DMD  6526  has a function of expressing (modulating) gradation of each pixel by switching a direction of reflection of light on each pixel position between a first direction A toward a projection lens  6580  and a second direction B deviating from the projection lens  6580 . Light (ON-light) incident upon each pixel position and reflected in the first direction A is introduced into the projection lens  6580  and projected on a projected surface (screen  6590 ). On the other hand, light (OFF-light) reflected by the DMD  6526  in the second direction B is not introduced into the projection lens  6580  but absorbed by a light absorber  6527 . 
     In the projector  6500 , the control portion  6550  controls to supply a pulse voltage to the semiconductor laser apparatus  940 , thereby dividing the red, green and blue semiconductor laser device portions  950 ,  960  and  965  of the semiconductor laser apparatus  940  in a time-series manner and cyclically driving the same one by one. Further, the control portion  6550  is so formed that the DMD  6526  of the optical system  6520  modulates light in response to the gradations of the respective pixels (R, G and B) in synchronization with the driving of the red, green and blue semiconductor laser device portions  950 ,  960  and  965 . 
     More specifically, an R signal related to driving of the red semiconductor laser device portion  950  (see  FIG. 27 ), a G signal related to driving of the green semiconductor laser device portion  960  (see  FIG. 27 ) and a B signal related to driving of the blue semiconductor laser device portion  965  (see  FIG. 27 ) are divided in a time-series manner not to overlap with each other and supplied to the respective laser devices of the semiconductor laser apparatus  940  by the control portion  6550  (see  FIG. 29 ), as shown in  FIG. 30 . In synchronization with the B, G and R signals, the control portion  6550  outputs a B image signal, a G image signal and an R image signal to the DMD  6526 . 
     Thus, the blue semiconductor laser device portion  965  emits a blue beam on the basis of the B signal in a timing chart shown in  FIG. 30 , while the DMD  6526  modulates the blue beam at this timing on the basis of the B image signal. Further, the green semiconductor laser device portion  960  emits a green beam on the basis of the G signal output subsequently to the B signal, and the DMD  6526  modulates the green beam at this timing on the basis of the G image signal. In addition, the red semiconductor laser device portion  950  emits a red beam on the basis of the R signal output subsequently to the G signal, and the DMD  6526  modulates the red beam at this timing on the basis of the R image signal. Thereafter the blue semiconductor laser device portion  965  emits the blue beam on the basis of the B signal output subsequently to the R signal, and the DMD  6526  modulates the blue beam again at this timing on the basis of the B image signal. The aforementioned operations are so repeated that an image formed by application of the laser beams based on the B, G and R image signals is projected on the projected surface (screen  6590 ). 
     The projector  6500  loaded with the semiconductor laser apparatus  940  according to the tenth embodiment of the present invention is constituted in the aforementioned manner. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims. 
     For example, while the first cleavage guide grooves (see  FIGS. 6 and 7 ) are formed to have the substantially rectangular shapes as viewed from the Z 1  side in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, both ends of each first cleavage guide groove  40   d  may be formed in wedge shapes where corners are located on the ends on Y 1  and Y 2  sides which are directions perpendicular to a ridge  11   d , and has a rhombic shape having rounded portions (substantially central portion in a direction Y) other than the corners located on the Y 1  and Y 2  sides, as in a first modification shown in  FIG. 31 . Alternatively, in the present invention, both ends of each of first cleavage guide grooves  40   e  may be formed in wedge shapes where corners are located on ends on Y 1  and Y 2  sides which are directions perpendicular to a ridge  11   d , and has a hexagonal shape having a central portion linearly extending in a direction Y, as in a second modification shown in  FIG. 32 . Alternatively, in the present invention, each of first cleavage guide grooves  40   f  may be formed to have a laterally long rhombic shape having corners located on Y 1  and Y 2  sides which are directions perpendicular to a ridge  11   d , as in a third modification shown in  FIG. 33 . According to the structures according to the first to third modifications, cracks are easily formed between the adjacent first cleavage guide grooves in the direction Y from the corners on the Y 1  and Y 2  sides when cleaving the wafer-state semiconductor laser device, and hence the wafer-state semiconductor laser device can be easily cleaved. The first cleavage guide grooves  40   d ,  40   e  and  40   f  are each an example of the “first groove” in the present invention. 
     While the first and second cleavage guide grooves, and the first, second and third device division grooves are provided on the semiconductor laser devices in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, all of the second cleavage guide grooves, and the first, second and third device division grooves except the first cleavage guide grooves may not be provided on the semiconductor laser devices. The cleavage guide grooves and the device division grooves may be provided after previously patterning portions to be provided with the cleavage guide grooves and the device division grooves. Thus, the cleavage guide grooves and the device division grooves can be more precisely provided. 
     While the first cleavage guide grooves are formed after forming the blue-violet semiconductor laser device portion in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the first cleavage guide grooves may be formed after forming the first insulating layer on the upper surface of the blue-violet semiconductor laser device portion, or the first cleavage guide grooves may be formed after forming the p-side electrode and the second insulating layer. In other words, the first cleavage guide grooves may be formed at any stage so far as it is formed before the wafer-state n-type GaN substrate side and the wafer-state n-type GaAs substrate side are bonded to each other. 
     While the first cleavage guide grooves and the first device division grooves are formed by photolithography and etching, and the second cleavage guide grooves and the second and third device division grooves are formed with a diamond point in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the cleavage guide grooves and the device division grooves may be formed by photolithography and etching, or with the diamond point or a laser beam. 
     While the semiconductor laser device is the two-wavelength semiconductor laser device including the blue-violet and red semiconductor laser device portions in each of the aforementioned fourth and fifth embodiments, the present invention is not restricted to this. In the present invention, the semiconductor laser device is not restricted to combination of the blue-violet and red semiconductor laser device portions, but it may be a two-wavelength semiconductor laser device including blue-violet and infrared semiconductor laser device portions, for example. 
     While the semiconductor laser device is formed by the two- or three-wavelength semiconductor laser device in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the semiconductor laser device is not restricted to the two- or three-wavelength semiconductor laser device so far as the semiconductor laser device is formed by bonding. For example, a plurality of single-wavelength semiconductor laser device portions may be bonded to each other, or semiconductor laser device portions having at least four different wavelengths may be bonded. 
     While the fusion layers are made of Au—Sn solder in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the fusion layers may be made of solder materials such as Au, Sn, In, Pb, Ge, Ag, Cu or Si or alloy materials thereof. Alternatively, other bonding method not employing solder may be employed. 
     While the p-side electrodes and the n-side electrodes on the n-type GaAs substrate side are formed by being alloyed by thermal treatment before bonding a plurality of the fusion layers and a plurality of the p-side electrodes in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the p-side electrodes and the n-side electrodes on the n-type GaAs substrate side may not be alloyed. Alternatively, the n-side electrodes on the n-type GaAs substrate side may be formed after bonding the plurality of fusion layers and the plurality of p-side electrodes in a case where alloying is not required or in a case where a temperature of thermal treatment in alloying is smaller than a melting temperature of the fusion layers. 
     While the p-type cladding layer of the red or infrared semiconductor laser device portion has the projecting portion, the recess portions formed on the both sides of the projecting portion, and the planar portions extending to the both sides of the recess portions and located below the lower surface of the projecting portion in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, the p-type cladding layer of the red or infrared semiconductor laser device portion may have a projecting portion and planar portions extending to the both sides of the projecting portion. In other words, no recess portion may not be provided on the red and infrared semiconductor laser device portions. 
     While the n-type GaN substrate and the n-type GaAs substrate are employed as a substrate in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, other substrate such as a GaP substrate and a Si substrate may be employed. 
     While the first device division grooves of the n-type GaAs substrate and the groove are formed to have substantially the same depth in each of the aforementioned first to tenth embodiments, the present invention is not restricted to this. In the present invention, depths of the first device division grooves and the groove may be different. 
     The “second grooves” of the present invention may be not only the broken-line shaped grooves employed in each of the aforementioned first to tenth embodiments, or the groove formed only on both ends on the Y sides of the wafer-state n-type GaAs substrate  220  but also second cleavage guide grooves  40   g  continuously linearly formed as in a fifth modification shown in  FIG. 34  or second cleavage guide grooves  40   h  formed in the form of dotted lines having shorter length and interval than the second cleavage guide grooves  40   c  (see  FIG. 15 ) as in a sixth modification shown in  FIG. 35 . In the case of  FIG. 35 , the groove portions having a length of about 50 μm can be formed at intervals of about 50 μm. The lengths and intervals of the second cleavage guide grooves  40   h  may not be equal to each other and may be independently changed. 
     In the RGB three-wavelength semiconductor laser device  980  employed in each of the aforementioned ninth and tenth embodiments, the green semiconductor laser device portion  960  or the blue semiconductor laser device portion  965  may be bonded onto the upper portion of the ridge of the red semiconductor laser device portion  950  similarly to the semiconductor laser device  400  of the second embodiment, or may be so bonded that the n-type GaN substrate  10  of the green and blue semiconductor laser device portions  960  and  965  is not located on the upper portion of the ridge of the red semiconductor laser device portion  950  similarly to the semiconductor laser device  500  of the third embodiment. 
     The two-wavelength semiconductor laser device  970  formed by the green and blue semiconductor laser device portions  960  and  965  is employed as the “first semiconductor laser device” of the present invention instead of the RGB three-wavelength semiconductor laser device  980  employed in each of the aforementioned ninth and tenth embodiments, and the red semiconductor laser device portion  950  may be employed as the “second semiconductor laser device” of the present invention. In this case, in the manufacturing process, removed portions between the red semiconductor laser device portions  950  are removed, and hence wire bonding portions of the two-wavelength semiconductor laser device  970  formed by the green and blue semiconductor laser device portions  960  and  965  are exposed outside. Thus, the RGB three-wavelength semiconductor laser device, in which the red semiconductor laser device portion  950  is directed upward when being mounted on the semiconductor laser apparatus, and the side of the two-wavelength semiconductor laser device  970  formed by the green and blue semiconductor laser device portions  960  and  965  is suitable for bonding onto a submount, can be constituted. 
     Thus, in the two-wavelength semiconductor laser device  970  formed by the green and blue semiconductor laser device portions  960  and  965 , heat can be directly radiated to the submount, and also in the red semiconductor laser device portion  950 , heat can be radiated to the submount through the two-wavelength semiconductor laser device  970  made of a nitride-based semiconductor having excellent thermal conductivity. Consequently, heat radiation capacity of the RGB three-wavelength semiconductor laser device can be further improved.