Abstract:
A semiconductor device formed by cutting a first substrate and a second substrate bonded together by a spacer, wherein: the spacer is disposed at an end of the first substrate after cutting; the second substrate is a semiconductor wafer formed with a light reception element or elements; and the first substrate has an optical element or an optical element set for converging light on the light reception element or elements. A method of manufacturing such a semiconductor device. A semiconductor device manufacture method includes: a step of detecting a warp of a semiconductor substrate; a step of holding the semiconductor substrate on a base under a condition that the warp is removed; a step of bonding an opposing substrate to the semiconductor substrate; and a step of cutting the opposing substrate, wherein the opposing substrate bonded to the semiconductor substrate is set with a size corresponding to the warp of the semiconductor substrate or with a gap to an adjacent opposing substrate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor device and its manufacture method, and more particularly to a semiconductor device having photoelectric conversion elements and its manufacture method. 
     2. Related Background Art 
     A conventional image pickup module has a semiconductor chip with light reception elements and a substrate having lenses for converging light on the light reception elements. The semiconductor chip and substrate are mounted on both sides of a spacer to be spaced apart by some distance. Light can be converged on a light reception plane of each light reception element so that a real image can be formed. 
     FIGS. 18A,  18 B and  18 C are broken perspective views illustrating a conventional image pickup module manufacture method. FIG. 18A shows a substrate  917  having lenses for converging light on a light reception element, FIG. 18B shows a spacer  901 , and FIG. 18C shows a semiconductor chip  503  having light reception elements  100 . According to a conventional image pickup module manufacture method, the substrate  917  and semiconductor chip  503  are bonded on both sides of the spacer  901  to form an image pickup module. If each of a plurality of image pickup modules is manufactured by this method, a number of manufacture processes are required including an alignment process for the semiconductor chip  503  and substrate  917 . 
     FIGS. 19A,  19 B and  19 C are schematic cross sectional views illustrating another conventional image pickup module manufacture method. 
     FIG. 19A is a schematic cross sectional view of a semiconductor wafer  910  formed with a plurality of semiconductor chips, the wafer having some warp caused by a passivation film or the like formed by a semiconductor device manufacture process. This warp has a height difference of, for example, about 0.2 mm between the highest and lowest positions in the case of an 8-inch wafer. A wafer with a warp has a roll shape, a saddle shape, a bowl shape or the like. 
     As shown in FIG. 19B, the warp of the semiconductor wafer  910  is removed by sucking the bottom surface of the wafer  910  by using a jig  950 . 
     Next, as shown in FIG. 19C, the semiconductor wafer  910  and a substrate  917  are bonded together via a spacer  901 . 
     Thereafter, suction of the semiconductor wafer  910  is released to dismount the semiconductor wafer  910  and lens substrate  917  from the jig  950 . This assembly of the semiconductor wafer and lens substrate is cut along each semiconductor chip and lens to form an image pickup module. A method of bonding together the semiconductor wafer  910  with semiconductor chips and the substrate  917  by a single alignment process is suitable for the manufacture of a plurality of image pickup modules. 
     (First Technical Issue) 
     After the semiconductor wafer  910  is bonded via the spacer  901  to the lens substrate  917  having a plurality of lenses for diverging light on light reception elements, each image pickup module is formed by dicing the substrate along each scribe line between semiconductor chips. During dicing, a force is applied to the substrate  917  from a dicing blade. This force may change the surface shape of a lens and hence a reflectivity thereof, degrading a focussing performance. 
     It is therefore an object of the invention to efficiently manufacture a semiconductor device such as an image pickup module without changing the surface shape of a lens during dicing. 
     (Second Technical Issue) 
     With the manufacture method illustrated in FIGS. 19A to  19 C, after suction of the semiconductor wafer  910  is released, the semiconductor wafer  910  tends to recover the original warp state. If the lens substrate  917  is bonded to the semiconductor wafer  910  with a warp on the convex surface side, the semiconductor wafer  910  and lens substrate  917  are likely to be peeled off in the peripheral area of the semiconductor wafer  910 . 
     Conversely, if the lens substrate  917  is bonded to the semiconductor wafer  910  with a warp on the concave surface side, the semiconductor wafer  910  and lens substrate  917  are likely to be peeled off in the central area of the semiconductor wafer  910 . 
     If the semiconductor wafer  910  and lens substrate  917  are peeled off at the worst, or if an adhesive layer between the semiconductor wafer  910  and lens substrate  917  is elongated, the distance between the semiconductor wafer  910  and lens substrate  917  changes so that light cannot be converged correctly on the light reception element, disabling desired image pickup in some cases. 
     It is therefore another object of the invention to manufacture a semiconductor device such as an image pickup module capable of realizing reliable image pickup by considering a warp of a semiconductor substrate such as the semiconductor wafer  910 . 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, there is provided a semiconductor device formed by cutting a first substrate and a second substrate bonded together by a spacer, wherein: the spacer is disposed at an end of the first substrate after cutting; the second substrate is a semiconductor wafer formed with a light reception element or elements; and the first substrate has an optical element or an optical element set for converging light on the light reception element or elements. 
     According to another aspect of the present invention, there is provided a semiconductor device manufacture method comprising: a step of bonding a first substrate and a second substrate by using a spacer; and a step of cutting the first and second substrates, wherein the step of cutting the first substrate cuts the first substrate at a position where the spacer is disposed under the first substrate. 
     According to still another aspect of the present invention, there is provided a semiconductor device manufacture method comprising: a step of holding the semiconductor substrate on a base under a condition that the warp is removed; a step of bonding an opposing substrate to the semiconductor substrates with a size adjusted according to the warp of the semiconductor substrate; and then a step of cutting the opposing substrate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a schematic top view showing the structure of a semiconductor device according to a first embodiment of the invention. 
     FIG. 1B is a schematic cross sectional view taken along line  1 B— 1 B shown in FIG.  1 A. 
     FIG. 1C is a top view of a semiconductor chip shown in FIG.  1 A. 
     FIG. 1D is a schematic cross sectional view showing the semiconductor device of the first embodiment connected to an external electronic circuit. 
     FIG. 2 is a schematic cross sectional view showing an area near light reception elements  822   a  and  822   b  shown in FIG.  1 C. 
     FIG. 3 is a diagram showing the positional relation between image pickup areas and the subject images picked up with a compound eye lens mounted on the image pickup module of the embodiment. 
     FIG. 4 is a diagram showing the positional relation between pixels when the image pickup areas shown in FIG. 3 are projected. 
     FIG. 5 is a broken perspective view illustrating a semiconductor manufacture method according to the invention. 
     FIG. 6 is a top view of the spacer  901  shown in FIG.  5 . 
     FIG. 7 is a top view of a semiconductor wafer  910  to which a spacer  901  is bonded. 
     FIG. 8 is a top view of the semiconductor wafer  910  having the spacer  901  to which an optical element set  917  is bonded. 
     FIG. 9 is a top view of the semiconductor wafer  910  having the spacer  901  to which all optical element sets  917  are bonded. 
     FIG. 10 is a schematic cross sectional view illustrating a dicing process to be executed after all optical element sets  917  are bonded. 
     FIG. 11 is a graph showing the spectral transmittance characteristics of an infrared ray cut filer. 
     FIGS. 12A,  12 B,  12 C and  12 D are schematic diagrams illustrating semiconductor device manufacture processes according to a second embodiment of the invention. 
     FIG. 13 is a schematic top view of an optical element set. 
     FIG. 14 is a schematic top view of an optical element set. 
     FIG. 15 is a schematic plan view of a semiconductor wafer with semiconductor chips. 
     FIG. 16 is a schematic plan view of the semiconductor wafer shown in FIG. 15 to which the optical element sets shown in FIGS. 13 and 14 are bonded. 
     FIG. 17 is a schematic plan view of the semiconductor wafer on the whole surface of which the optical element sets are mounted. 
     FIGS. 18A,  18 B, and  18 C are broken perspective views illustrating a conventional image pickup module manufacture processes. 
     FIGS. 19A to  19 C are schematic cross sectional views illustrating another conventional image pickup module manufacture processes. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention will be described with reference to the accompanying drawings. 
     In the description of a semiconductor device of this invention, an image pickup module is used by way of example. 
     [First Embodiment] 
     FIG. 1A is a schematic top view showing the structure of a semiconductor device according to the first embodiment of the invention. FIG. 1B is a schematic cross sectional view taken along line  1 B— 1 B shown in FIG.  1 A. FIG. 1C is a top view of a semiconductor chip  503  shown in FIG.  1 A. FIG. 1D is a schematic cross sectional view showing the semiconductor device of the first embodiment connected to an external electronic circuit. 
     Referring to FIGS. 1A to  1 D, reference numeral  560  represents an infrared ray cut filter. Reference numeral  501  represents a light transmissive member constituting a first substrate after being cut. Reference numeral  506  represents a stop light shielding layer made of light shielding material, for example, offset printed on the infrared ray cut filter  560  on the light transmissive member  501 . Reference numeral  512  represents a compound eye optical element having a compound eye lens constituted of the infrared ray cut filter, stop light shielding layer  506 , and convex lenses  600   a  and  600   c  and unrepresented convex lenses  600   b  and  600   d . In this embodiment, although the compound eye optical element having the compound eye lens constituted of four convex lenses is used, the number of lenses is not limited only to this, but it may be determined as desired. For example, an optical element having only one lens may be used. Reference symbols  810   a ,  810   b ,  810   c  and  810   d  represent stop apertures formed through the stop light shielding layer  506 . It is preferable that the optical axes of the lenses  600   a ,  600   b ,  600   c  and  600   d  are disposed coaxially with the stop apertures  810   a ,  810   b ,  810   c  and  810   d . The infrared ray cut filter  560  may be omitted. In this case, a thinner image pickup module can be formed. Reference numeral  503  represents a semiconductor chip as a second substrate after being cut, the semiconductor chip having pixels (not shown) including light reception elements disposed two-dimensionally. Reference numeral  522  represents a spacer which determines the distance between the compound eye optical element  512  and semiconductor chip  503 . Reference numeral  509  represents an adhesive member for bonding the compound eye optical element  512  and semiconductor chip  503  via the spacer  522 . Reference numeral  513  represents an electrode pad or external terminal for externally outputting a signal supplied from a light reception element such as a MOS type image pickup element or a CCD image pickup element or a light emitting element. Reference numeral  508  represents a light shielding member formed in spaces surrounded by the compound eye optical element  512 , spacer  522  and semiconductor chip  503 , the light shielding member preventing optical crosstalk between the four convex lenses. Reference numeral  516  represents a micro lens for increasing a light conversion efficiency of each light reception element. Reference symbols  820   a ,  820   b ,  820   c  and  820   d  represent light reception areas in which light reception elements are disposed two-dimensionally on the semiconductor chip  503 . Reference numeral  514  represents an AD convertor for converting an output signal from each light reception element into a digital signal. Reference numeral  515  represents a timing generator for generating a timing signal for a photoelectric conversion operation of each light reception element. The spacer  522  may be made of any member which can determine the distance between the semiconductor chip  503  and compound eye optical element  512 . For example, members having a predetermined length may be used, or adhesive mixed with beads may be used. 
     Reference numeral  517  represents a multi-layer printed circuit board to be used as an external electronic circuit substrate. Reference numeral  520  represents a bonding wire for electrically connecting the electrode pad  513  and an unrepresented electrode pad on the multi-layer printed circuit board  517 . Reference numeral  521  represents thermosetting or ultraviolet ray hardening resin for sealing the peripheral area of the electrode pad  513  and bonding wire  520 . In this embodiment, epoxy resin is used as thermosetting or ultraviolet ray hardening resin. Instead of electrical connection by the bonding wire  520 , electrical connection by a TAB film may also be used. The ultraviolet ray hardening resin  520  is coated on the whole outer peripheral area of the image pickup module in order to obtain a mount stability of the image pickup module on the multi-layer printed circuit board. Reference symbols  822   a  and  822   b  represent light reception elements. 
     The image pickup module as the semiconductor device of the invention is characterized in that the spacer  522  is disposed at the peripheral sides of the compound eye optical element  512 . Namely, the light permissive member  501  as the first substrate before being cut is bonded via the spacer  522  to the semiconductor wafer as the second substrate before being cut into semiconductor chips  503 , and thereafter, the area where the spacer  522  exists under the light permissive member  501  is cut to form each image pickup module. 
     The spacer  522  is therefore disposed at the peripheral sides of the light transmissive member  501 . 
     The more detailed description will be given for an image pickup module manufacture method of this embodiment. As shown in FIG. 11, the infrared ray cut filter  560  transmits 80% or more of electromagnetic waves (such as ultraviolet rays) having a wavelength in the range from 350 nm to 630 nm and hardly transmits electromagnetic waves (such as infrared rays) having a wavelength of 250 nm or shorter or 850 nm or longer. 
     The infrared ray cut filter  560  is formed on the whole surface of the light transmissive member  501  by vapor deposition or the like, and on this infrared ray cut filter  560  the stop light shielding layer  506  is formed. The stop light shielding layer  506  is disposed so as not to be superposed upon the adhesive member  509  along an ultraviolet ray incidence direction, so that ultraviolet ray hardening epoxy resin can be sufficiently hardened to form the adhesive member  509 . The stop light shielding layer has an island outer shape. In this invention, the adhesive member  509  is not limited only to ultraviolet hardening epoxy resin so that the stop light shielding layer  506  and adhesive member  509  may be superposed upon each other along the ultraviolet ray incidence direction. In this specification, the ultraviolet ray incidence direction is a direction indicated by an arrow X. 
     The semiconductor chip  503  and spacer  522  are bonded by displacing one from the other because the bonded structure is suitable for electrically connecting the electrode pad  513  and an external electronic circuit by a wiring lead by bonding or the like. The semiconductor chip  503  and spacer  522  may be bonded not by displacing one from the other. In this case, the compound eye optical element  512  is preferably disposed not by displacing it from the spacer  522 . 
     The semiconductor chip  503  will be described in more detail with reference to FIGS. 1B and 1C. As shown in FIG. 1B, between the compound eye optical element  512  and compound eye optical system  503 , the spacer  522  made of resin, glass, silicon or the like is disposed in order to hold them at a predetermined distance. The spacer  522  and semiconductor chip  503  may be bonded together by utilizing a bonding process to be used when a silicon on insulator (SIO) substrate is formed. It is preferable to bond them together by using adhesive metal which contains aluminum or indium. The convex lenses  600   a ,  600   b ,  600   c  and  600   d  are formed on the light transmissive member  501  by a replica method, an injection molding method, a compression molding method or the like. The convex lens  600   a    600   d  is a spherical surface Fresnel convex lens or a circular, axis-symmetrical, non-spherical surface Fresnel convex lens, respectively made of resin with which a curved image surface can be corrected more reliably as compared to a usual optical system using a continuous image surface. 
     The convex lenses  600   a  to  600   d  are bonded to the light transmissive member  501  by resin. A portion of resin is flowed in some cases to the peripheral area of each convex lens  600   a - 600   d  such as an area between the convex lenses  600   a  and  600   c . If the flowed resin reaches the cut surface of the light transmissive member, a force may be applied to the resin during cutting along a direction of peeling off the resin from the light transmissive member  501 . In such a case, the convex lenses  600   a  to  600   d  may have distortion. It is therefore preferable that the flowed resin does not reach the cut surface of the light transmissive member  501 . 
     The position of each of the stop apertures  810   a ,  810   b ,  810   c  and  810   d  along the optical axis direction determines a main light beam outside the optical axis of the optical system. Therefore, the stop position is very important from the viewpoint of controlling various aberrations. Since each convex lens  600   a - 600   d  is formed on the image side, various optical aberrations can be corrected properly if the stop is positioned near at the center of a spherical surface approximating a Fresnel lens surface. If a color image is desired to be picked up, a green (G) transmissive filer, a red (R) transmissive filter and a blue (B) transmissive filter are disposed, for example, in a Bayer layout, near at each convex lens  600   a - 600   d  along the optical axis. If a particular color image or an X-ray image is desired to be picked up, the particular color filter or phosphor is disposed. In this embodiment, although not shown, a green (G) transmissive filer, a red (R) transmissive filter and a blue (B) transmissive filter are disposed in a Bayer layout. 
     The micro lenses  516  and light shielding member  508  are formed on the semiconductor chip  503 . The micro lens  516  converges light on the light reception element in order to pick up an image of, for example, a subject with a low luminance. The light shielding member  508  prevents generation of optical crosstalk between light transmitted through the convex lens  600   a  and light transmitted through the convex lens  600   c . The light shielding member is disposed between adjacent convex lenses. 
     If the light reception element  822   a  and other elements shown in FIG. 1C are CMOS sensors, it is easy to mount the A/D convertor  514  and the like on the semiconductor chip  503 . If the A/D convertor  514  and the like and the adhesive member  509  are superposed upon each other on the semiconductor chip  503 , the area of the semiconductor chip  503  can be reduced, resulting in a low cost. 
     The adhesive member  509  is preferably disposed spaced apart from the dicing line. In this case, it is possible to prevent the quality of the image pickup module from being lowered by the adhesive member  509  melted or broken into fine pieces or carbon particles by friction heat of the dicing blade and attached to the convex lenses  600   a  to  600   d.    
     The micro lenses are disposed on the light reception areas  820   a ,  820   b ,  820   c  and  820   d  such that peripheral lenses such as  516  are shifted more toward the center of the line interconnecting the centers of the light reception areas. 
     FIG. 1D shows the multi-layer printed circuit board  517  as an external electric circuit board, bonding wires for electrically connecting the multilayer printed circuit board  517  side and the electrode pads  513 , and the thermosetting or ultraviolet hardening resin  521  for sealing the peripheral area of the electrode pad  513  and bonding wire  520 . 
     Sealing by the adhesive member  509  and thermosetting or ultraviolet hardening resin  521  can reliably prevent deterioration of the micro lenses  216  and filter layers to be caused by entered dusts, moisture in the air and electrolytic corrosion of aluminum layers. 
     The thermosetting or ultraviolet ray hardening resin  521  is coated on the whole outer peripheral area of the image pickup module in order to establish the mount reliability of the image pickup module  511  on the multi-layer printed circuit board  517 . 
     Since the electrode pad  113  and multi-layer printed circuit board  517  are connected by the bonding wire  520 , an ITO film or via metal body is not necessary and the cost can be reduced correspondingly. In place of the bonding wire  520 , a TAB film may be used. 
     FIG. 2 is an enlarged schematic cross sectional view showing an area near the light reception elements  822   a  and  822   b  shown in FIG.  1 C. In FIG. 2, reference symbols  516   a  and  516   b  represent micro lenses formed above the light reception elements  822   a  and  822   b , reference symbols  823   a  and  823   b  represent incident light fluxes passed through the stop apertures  810   a  and  810   b . The micro lens  516   a  is upward eccentric relative to the light reception element  822   a , whereas the micro lens  516   b  is downward eccentric relative to the light reception element  822   b.    
     Only the light flux  823   a  is incident upon the light reception element  822   a  and only the light flux  823   b  is incident upon the light reception element  822   b . The light fluxes  823   a  and  823   b  are inclined downward and upward relative to the light reception planes of the light reception elements  822   a  and  822   b , and are directed toward the stop apertures  810   a  and  810   b.    
     By properly selecting the eccentricity amounts of the micro lenses  516   a  and  516   b , only a desired light flux becomes incident upon each light reception element  822 . The eccentricity amounts can be set so that a subject light beam passed through the stop aperture  810   a  is received mainly in the light reception area  820   a , a subject light beam passed through the stop aperture  810   b  is received mainly in the light reception area  820   b , . . . .    
     With reference to FIGS. 3 and 4, a mechanism of processing an electric signal converted in the light reception areas  820   a  to  820   d  of the image pickup module as a semiconductor device according to the first embodiment of the invention will be described. FIG. 3 is a diagram showing the positional relation between image pickup areas and the subject images picked up with the compound eye lens mounted on the image pickup module of the embodiment. FIG. 4 is a diagram showing the positional relation between pixels when the image pickup areas shown in FIG. 3 are projected. In FIG. 3, reference symbols  320   a ,  320   b ,  320   c  and  320   d  represent four light reception element arrays formed on the semiconductor chip  503 . For the purposes of description simplicity, it is assumed that each of the light reception element arrays  320   a ,  320   b ,  320   c  and  320   d  has 8×6 pixels. The number of pixels is selected as desired and not limited only to the embodiment. The light reception element arrays  320   a  and  320   d  output G image signals, the light reception element array  320   b  outputs R image signals, and the light reception element array  320   c  outputs B image signals. Pixels in the light reception element arrays  320   a  and  320   d  are shown by a white square, pixels in the light reception element array  320   b  are shown by a hatched square, and pixels in the light reception element array  320   c  are shown by a black square. 
     Separation zones each having the size of one pixel in the horizontal direction and three pixels in the vertical direction are formed between adjacent light reception element arrays. Therefore, the center of a line connecting the centers of the light reception element arrays for outputting G image signals has the same vertical and horizontal positions. Reference symbols  351   a ,  351   b ,  351   c  and  351   d  represent subject images. Since pixels are disposed in a pixel shift layout, the centers  360   a ,  360   b ,  360   c  and  360   d  of the subject images  351   a ,  351   b ,  351   c  and  251   d  are offset from the centers of the light reception element arrays  320   a ,  320   b ,  320   c  and  320   d  by a quarter pixel distance toward the center  320   e  of all the light reception element arrays. 
     As the light reception element arrays are reversely projected on the plane at a predetermined distance on the subject side, a projection shown in FIG. 4 is obtained. Also on the subject side, reversely projected pixel images in the light reception element arrays  320   a  and  320   d  are shown by a white square  362   a , reversely projected pixel images in the light reception element array  320   b  are shown by a hatched square  362   b , and reversely projected pixel images in the light reception element array  320   c  are shown by a black square  362   c.    
     Reversely projected images of the centers  360   a ,  360   b ,  360   c  and  360   d  of the subject images are superposed as one point  361 , and each pixel image in the light reception element arrays  320   a ,  320   b ,  320   c  and  320   d  is reversely projected so as not to superpose the centers of respective pixels. Since the white square outputs a G image signal, the hatched square outputs an R signal and the black square outputs a B signal, the subject can be sampled by pixels in the manner similar to an image pickup device having color filters disposed in the Bayer layout. 
     As compared to an image pickup system using a single image pickup lens, the Bayer layout disposing R, G, B and G color filters for 2×2 pixels on the semiconductor chip  503  can form a subject image having a size of 1 divided by a root of 2, assuming that the pixel pitch is fixed. The focal length of the image taking lens is therefore shortened by 1 divided by a root of 2, i.e., by ½. This is considerably suitable for making a camera compact. 
     The operation of the image pickup module shown in FIGS. 1A to  1 D will be described briefly. A subject light beam incident upon the optical element  512  passes through the stop apertures  810   a  to  810   d  and convex lenses  600   a  to  600   d  under the stop apertures and forms a plurality of subject images on the semiconductor chip  503 . The images are converged via the micro lenses  516  on respective light reception elements. 
     Since the color filters are disposed, four subject images of R, G, B and G are formed on respective light reception elements which convert received light into electric signals. 
     A method of manufacturing an image pickup module as a semiconductor device according to the invention will be described in detail with reference to FIGS. 5 to  10 . FIG. 5 is a broken perspective view illustrating the semiconductor manufacture method according to the first embodiment of the invention. Referring to FIG. 5, reference numeral  901  represents a spacer including spacers  522   a  and  522   b , reference symbols  503   a  and  503   b  represent semiconductor chips, and reference numeral  917  represents an optical element set having light transmissive members  501   a  and  501   b  formed with lenses, light shielding layers, unrepresented color filters and the like. First, the optical element set  917  having the light transmissive members  501   a  and  501   b  formed with convex lenses  600   a  to  600   d  is bonded to the spacer  901 . By dicing the area between the semiconductor chips  503   a  and  503   b  along a dicing line, an image pickup module with the semiconductor chip  503   a  and an image pickup module with the semiconductor chip  503   b  can be formed. A dicing area is an area where the space is formed under the light transmissive member  501  as the first substrate. A dicing line may be defined by a groove in the optical element set  917  formed by etching, metal marks formed through photolithography techniques, or resin projections formed by a replica. If the resin projections are formed by a replica at the same time when the convex lenses  600   a  to  600   d  are formed, the number of manufacture processes can be reduced. 
     FIG. 6 is a top view of the spacer  901  shown in FIG.  5 . The spacer  901  is separated by a division line  903  into the spacers  522   a  and  522   b . The spacer  901  is formed with a plurality of openings  902  for guiding light fluxes passed through the convex lenses  600   a  to  600   d  to the light reception elements  822 . 
     FIGS. 7 to  10  are top views of a semiconductor wafer illustrating the processes of manufacturing semiconductor devices according to the embodiment. FIG. 7 is a top view of the semiconductor wafer  910  to which a spacer  901  is bonded. FIG. 8 is a top view of the semiconductor wafer  910  having the spacer  901  to which an optical element set  917  is bonded. FIG. 9 is a top view of the semiconductor wafer  910  having the spacers  901  to which all optical element sets  917  are bonded. FIG. 10 is a schematic cross sectional view illustrating a dicing process to be executed after all optical element sets  917  are bonded. 
     The semiconductor device manufacture method according to the invention will be described in detail. First, twenty two semiconductor chips  503  are formed on the semiconductor wafer  910  as the second substrate. Each semiconductor chip  503  has the structure shown in FIG.  1 C. The number of semiconductor chips to be formed on the semiconductor wafer  910  is selected as desired. 
     Since the semiconductor wafer  910  may have some warp, the semiconductor wafer  910  is sucked when the optical element sets  917  are bonded, in order to remove the warp of the semiconductor wafer  910 . 
     After the suction of the semiconductor wafer  910  is released later, a force is applied to the semiconductor wafer  910  to recover the original shape. This force may collide some optical element sets  917  with each other so that the distance between the semiconductor wafer  910  and the optical element sets  917  may be changed. In order not to change this distance, it is preferable to form some gap between adjacent semiconductor chips  503 . 
     There is a strong tendency that the area of a semiconductor wafer is becoming large. When the optical element sets  917  are bonded to the semiconductor wafer  910  in a sucked state, some gap formed between adjacent semiconductor chips  503  helps to manufacture image pickup modules of good quality. 
     The spacer  901  is aligned with the two semiconductor chips  503  and bonded to an adhesive member  509  on the semiconductor chips  503 . An arrow J indicates the position of a dicing line (FIG.  7 ). 
     The semiconductor wafer  910  made of crystal has electrical, optical, mechanical and chemical anisotropical characteristics. After the orientation of a pulled-up ingot is measured precisely by using X-ray diffraction, the ingot is sliced. Prior to slicing the ingot, a cylindrical ingot is formed with a straight portion called an orientation flat  909  which indicates the crystal orientation. 
     If a semiconductor element pattern of the semiconductor chip  503  is formed in alignment with the orientation flat  909 , precise alignment between the optical element set  917  and the wafer can be established by using a reference pattern formed on the optical element set  917  and the orientation flat  909 . 
     If the size of the optical element set  917  is set to the maximum size capable of being accommodated in the effective exposure size of a stepper, the number of image pickup modules manufactured from one wafer can be made large so that it is effective from the viewpoint of cost. 
     After the spacer  901  is bonded to the semiconductor chips  503 , the optical element set  917  is bonded by using thermosetting or ultraviolet ray hardening epoxy resin in the state that the opening  902  of the spacer  901  is aligned with the corresponding convex lens  600 . An arrow K indicates the position of the division line  903  of the optical element set  917  (FIGS.  6  and  8 ). 
     After the epoxy resin is semi-hardened by radiating ultraviolet rays, it is pressed until a predetermined gap is formed. Thereafter, the resin is completely hardened by a thermal treatment to fix the gap between the optical element set  917  and semiconductor wafer  910  so that a subject image can be focussed sharply on the light reception element array  912 . 
     The adhesive member  509  is preferably disposed spaced apart from the division line  903  or dicing line. In this case, it is possible to prevent the quality of the image pickup module from being lowered by the epoxy resin melted or broken into fine pieces or carbon particles by friction heat of the dicing blade and attached to the convex lenses  600   a  to  600   d.    
     The optical element set  917  is bonded to each spacer  901  in the similar manner (FIG.  9 ). 
     Epoxy resin is used because hardening is gentle and hardening contraction variation is rare so that stress can be relaxed. In this embodiment, although thermosetting resin can be used as the material of the adhesive member, it is more preferable to use ultraviolet ray hardening resin because heating sufficient for hardening the thermosetting resin may deteriorate the printed coat of the micro lens, replica, and stop light shielding layer  506  respectively formed on the semiconductor wafer  910 . 
     The infrared ray cut filter  560  is formed in the peripheral area of the stop light shielding when the spectral transmittance of the infrared ray cut filter in this area is regulated to transmit ultraviolet rays, the epoxyresin can be hardened by ultraviolet ray radiation from a front of the semiconductor wafer  910 . 
     If the optical element sets  917  are bonded and fixed before each semiconductor chip  503  is cut from the semiconductor wafer  910 , the semiconductor wafer  910  and optical element sets  917  can be made parallel, i.e., the distance between the semiconductor wafer  910  and each optical element set can be made equal, more than if the optical element sets are not bonded and fixed before each semiconductor chip is cut. It is therefore possible that one-side unsharpness of an optical image is difficult to occur. 
     Lastly, the semiconductor wafer  910  is diced at the positions indicated by an arrow J, and the spacer  901  and optical element set  917  are cut at the position indicated by an arrow K. In dicing the semiconductor wafer  910 , a cutting working system or a laser working system disclosed, for example, in Japanese Patent Application Laid-Open Nos. 11-345785 and 2000-061677 may be used. 
     As shown in FIG. 10, if a dicing blade is used, only the semiconductor wafer  910  is diced along the direction indicated by the arrow J from the bottom of the semiconductor wafer while cutting water is poured to cool the semiconductor wafer  910 . In FIG. 10, reference numeral  523  represents a dicing blade. 
     Next, only the optical element set  917  and spacer  901  are cut from the top surface of the optical element set  917 . 
     More specifically, as the dicing blade  523  rotates in the direction indicated by an arrow L, the dicing blade pushes in this direction the semiconductor wafer  910  before the semiconductor chips  503  are separated. If the resin layer coupled to the convex lenses  600   a ,  600   b ,  600   c  and  600   d  exists on the dicing line, a force is applied to the resin layer in the direction of peeling off the resin layer from the glass substrate of the compound eye optical element  512 , and the surface precision of the convex lenses  600   a ,  600   b ,  600   c  and  600   d  may be degraded. 
     In this embodiment, since resin does not exist on the dicing line along which the dicing blade moves, a large force will not be applied to the convex lenses  600   a ,  600   b ,  600   c  and  600   d  so that the above problem can be solved. It is also possible to prevent the quality of the image pickup module from being lowered by the resin melted or broken into fine pieces or carbon particles by friction heat of the dicing blade  523  and attached to the convex lenses  600   a  to  600   d.    
     With the above processes, the semiconductor wafer  910  and optical element set  917  are separated into rectangular pieces to obtain image pickup modules  511  shown in FIGS. 1A to  1 D. With the cutting processes described above, triangular pieces or hexagonal pieces may also be formed. 
     The image pickup module  511  is connected to the multi-layer printed circuit board  517  as shown in FIG.  1 D. 
     In the above embodiment, two spacers are used for the spacer  901  and two compound eye optical elements are used as the optical element set  917 . Three or four spacers and compound eye optical elements may also be used. In order to reduce the number of position alignment processes, the spacer  901  and the like may has the size similar to the semiconductor wafer  910 , and the openings  902  and convex lenses  600  are formed at positions corresponding to each semiconductor chip  503  on the semiconductor wafer  910 . 
     In this embodiment, although the image pickup module is used as an example of the semiconductor device, the embodiment may be applied to an image forming module having electron emitting elements formed on a semiconductor wafer  910  and light emitting elements such as phosphors formed on an opposing substrate, with a spacer  522  being interposed therebetween. 
     As described so far, according to the invention, a force is prevented from being applied to the first substrate  917  on the spacer during dicing. It is therefore possible to prevent the surface shape of a lens or the like formed on the first substrate from being changed. It is possible to provide a method of easily manufacturing a semiconductor device such as an image pickup module without changing the lens surface shape and without deterioration of a focussing performance. 
     [Second Embodiment] 
     FIGS. 12A to  12 D are schematic diagrams illustrating semiconductor device manufacture processes according to a second embodiment of the invention. In FIGS. 12A to  12 D, reference numeral  910  represents a semiconductor substrate with a warp such as a semiconductor wafer having a plurality of semiconductor chips formed thereon, reference numeral  950  represents a jig for sucking the semiconductor wafer  910  from its bottom surface to remove the warp of the semiconductor wafer, and reference numeral  917  represents optical element sets as an opposing substrate. 
     In FIGS. 12A to  12 D, like elements represented by identical reference numerals to those of the first embodiment have been described earlier, and the description thereof is omitted. As shown in FIG. 12A, the semiconductor wafer  910  has some warp caused by a passivation film formed by a semiconductor device manufacture process. This warp has a height difference of about 0.2 mm between the highest and lowest positions in the case of an 8-inch wafer. A wafer with a warp has a roll shape, a saddle shape, a bowl shape or the like. 
     In order to prevent the generation of stress when the suction of the bottom surface of the semiconductor wafer  910  is released, it is necessary to adjust the number of optical elements in each optical element set. Namely, if the semiconductor wafer  910  has a warp whose convex and concave curves have a low frequency as small as about twice the diameter of the semiconductor wafer, the number of optical elements in each optical element set is made large to cover the semiconductor wafer  917  with a small number of optical element sets. If the semiconductor wafer  910  has a warp whose convex and concave curves correspond to about the diameter of the semiconductor wafer, the number of optical elements in each optical element set is made small to cover the semiconductor wafer  917  with a number of optical element sets. A gap P is preferably about 10 μm to 500 μm by considering a size variation of optical element sets. The frequency characteristics of the warp of the semiconductor wafer  910  can be obtained by frequency analysis of the surface shape. There is a general tendency that the larger the wafer size, the convex and concave curves have the smaller frequency. Therefore, the semiconductor wafer  910  is sucked from its bottom surface by using the jig  950  when optical element sets  917  are bonded to the semiconductor wafer  910 , to thereby remove the warp of the semiconductor wafer  910  (FIG.  12 B). More specifically, the semiconductor wafer  910  is sucked to the jig  950  by using an unrepresented sucking machine so that the whole bottom surface of the semiconductor wafer  910  becomes in contact with the jig. In this state, a plurality of spacers  901  are bonded to the semiconductor wafer  910 , with the mount positions being aligned. Next, the optical element sets  917  are aligned in position with the optical element sets  917 , and bonded thereto by using adhesive (FIG.  12 C). After the adhesive is hardened, the suction is released. 
     The spacer  901  is disposed for bonding together the semiconductor wafer and optical element sets  917 . This spacer may be omitted. 
     The size of an optical element set  917  are determined corresponding to the size of the warp of the semiconductor wafer  910 . It is necessary that if the semiconductor wafer  910  has a larger warp, the spacer  901  and optical element set  917  are made smaller. The reason for this is as follows. When the suction of the semiconductor wafer  910  to the jig  950  is released, a force is generated to recover the original shape of the semiconductor wafer  910 . This force makes adhesive have a creeping phenomenon. If the spacer  901  and optical element set  917  are made larger even if the convex warp is large, the distance of the optical element set  917  and semiconductor wafer  910  becomes longer from the semiconductor chip  503  nearer to the center of the semiconductor wafer  910 . In this case, the focus point of the image pickup module is displaced from pixels. 
     Conversely, if the spacer  901  and the like is made larger, a balance between the compound eye optical element  512  and semiconductor chip  503  of each image pickup module can be obtained more easily and the number of position alignments is reduced. From these viewpoints, if a warp of a bowl shape has a height difference of about 0.2 mm between the highest and lowest positions in the case of an 8-inch wafer, and about six hundreds semiconductor chips  503  having a side length of about 6 mm are to be formed, the size of the spacer  901  and the like is set to the size of three semiconductor chips disposed in parallel to the side. FIGS. 12A to  12 D show pluralities of an optical element sets  917 , it also can be only one optical element  917  set on the semiconductor wafer  710 . 
     The gap P which is between a plurality of an optical element sets  917  is set with a size corresponding to the warp of the semiconductor substrate in order to prevent the distance between the semiconductor wafer  910  and optical element set  917  from being changed by the adhesive layer elongated or peeled-off by the creeping phenomenon of adhesive which occurs when a plurality of optical element sets  917  abut on each other when the suction of the semiconductor wafer  910  to the jig  950  is released (FIG.  12 D). Since there is the tendency that semiconductor wafers are becoming large, when the optical element sets  917  are bonded to the semiconductor wafer  910  in a sucked state, some gap P formed between adjacent semiconductor chips helps to manufacture image pickup modules of good quality. The optical element such as shown in FIG.  1 A and the optical element set  517  such as shown in FIG. 5 may be used. The optical element set  517  shown in FIG. 5 has two optical elements. The number of optical elements to be cut from the optical element set is determined as desired. 
     With reference to FIGS. 13 and 14, other examples of the optical element set will be described. 
     FIG. 13 is a schematic top view of an optical element set  962 . In FIG. 13, reference numeral  963  represents a lens. The optical element set  962  has a cross shape. By using this optical element set  962 , five image pickup modules each having one lens can be manufactured. The pitch of lenses  963  is the same as that of semiconductor chips on an unrepresented semiconductor wafer  910  so that each image pickup module has the lens of the optical element set  962  bonded to the semiconductor wafer  910 . 
     FIG. 14 is a schematic top view of an optical element set  964 . In FIG. 14, reference numeral  965  represents a lens. The optical element set  964  has a rectangular shape. By using this optical element set  964 , four image pickup modules each having one lens can be manufactured. The pitch of lenses  965  is the same as that of semiconductor chips on an unrepresented semiconductor wafer  910  so that each image pickup module has the lens of the optical element set  964  bonded to the semiconductor wafer  910 . 
     The shape of the optical element set is not limited only to the cross shape or rectangular shape, but it may be a T-character shape, an I-character shape, an L-character shape or the like. 
     With reference to FIGS. 15 to  17 , the semiconductor device manufacture processes according to the embodiment will be described in more detail. 
     FIG. 15 is a schematic plan view of a semiconductor wafer with semiconductor chips. In FIG. 15, reference numeral  960  represents a semiconductor wafer, and reference numeral  961  represents a semiconductor chip. 
     FIG. 16 is a schematic plan view of the semiconductor wafer shown in FIG. 15 to which the optical element sets shown in FIGS. 13 and 14 are bonded. 
     FIG. 17 is a schematic plan view of the semiconductor wafer on the whole surface of which the optical element sets are mounted. 
     Normally, the semiconductor wafer  960  is formed with as many semiconductor chips  961  as possible as shown in FIG.  15 . However, as described with reference to FIG.  7  and the like, if the optical element set  917  and spacer  901  are bonded to two semiconductor chips  503 , some semiconductor chips  961  cannot be used in some cases. These semiconductor chips  961  are those formed in the peripheral area of the semiconductor wafer  960  excepting the area near the orientation flat. 
     In order to avoid this, as shown in FIG. 16, the optical element sets  963  are disposed in a zigzag manner and bonded to the semiconductor wafer in such a manner that the corners of the optical element sets  965  are aligned with the convex corners of the optical element sets  963 . As shown in FIG. 17, the optical element sets  965  and  963  are disposed on all semiconductor chips  961  on the semiconductor wafer  960 . The gap Q is formed between adjacent optical element sets  963  along their longitudinal direction by considering the warp of the semiconductor wafer  960 . In this embodiment, for the purposes of description simplicity, the optical element sets  963  and  965  shown in FIGS. 13 and 14 are used. However, as shown in FIG. 17, some optical element sets  963  and  965  cannot be used. To avoid this, in a practical case, optical element sets having the shapes in conformity with those of the semiconductor chips  961  formed on the semiconductor wafer  960  are used to manufacture image pickup modules. 
     As described so far, according to the invention, a semiconductor manufacture method is provided which can make a semiconductor substrate and an opposing substrate be difficult to be peeled off even if the semiconductor substrate tends to recover the original warp when it is dismounted from a jig (base).