Device transferring method

A device transferring method for transferring a plurality of devices to a mounting substrate provided with a plurality of electrodes includes: a step of adhering an expandable tape to the plurality of devices formed on a front surface side of a substrate through a buffer layer; a step of applying a laser beam to the buffer layer from a back surface side of the substrate, to break the buffer layer; a step of moving the tape in a direction for spacing away from the substrate to separate the substrate and the plurality of devices from each other, thereby transferring the plurality of devices to the tape; a step of expanding the tape in such a manner that the layout of the plurality of devices corresponds to the layout of the plurality of electrodes; and a step of bonding the plurality of devices to the plurality of electrodes at once.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a device transferring method for transferring a plurality of devices from a wafer to a mounting substrate.

Description of the Related Art

Where a wafer formed with a plurality of devices is divided along division lines (streets), a plurality of device chips each including the device are thereby obtained. The division of the wafer is carried out using, for example, a cutting apparatus, a laser processing apparatus or the like. In the technique using the laser processing apparatus, a laser beam of such a wavelength as to be absorbed in the wafer is applied along the division lines, to evaporate the wafer, thereby dividing the wafer. Japanese Patent Laid-Open No. Hei 10-305420 discloses a technique in which a laser beam oscillated in a pulsed form is applied along division lines to form grooves in the wafer, and the wafer is divided along the grooves. Then, the device chips obtained by the division of the wafer are mounted onto a mounting substrate, whereby a desired package substrate is produced. Examples of the device to be formed on the wafer include an optical device such as a light emitting diode (LED). For example, where an n-type semiconductor layer and a p-type semiconductor layer forming a pn junction are epitaxially grown over a substrate formed of sapphire or SiC, an optical device can be formed thereby.

In addition, for transferring optical devices from a wafer to a mounting substrate, there is known a technique of separating the optical devices from the wafer without dividing the wafer. Japanese Patent Laid-open No. 2004-72052 discloses a technique in which after a semiconductor film for constituting optical devices is formed on a front surface of a wafer, a laser beam is applied from the back surface side of the wafer to form a modified layer in the vicinity of the interface between the wafer and the semiconductor layer, and the wafer and the semiconductor layer are separated from each other at the modified layer.

SUMMARY OF THE INVENTION

At the time of mounting the devices to the mounting substrate as above-mentioned, it is necessary to transfer the devices formed on the wafer to the mounting substrate. The transfer of the devices is carried out, for example, by repeating an operation of picking up the device from the wafer, transferring the device onto the mounting substrate and die-bonding the device to a predetermined position on the mounting substrate, for each of the devices. In this case, a long-time transferring operation is needed for mounting all the devices onto the mounting substrate, so that productivity is lowered.

The present invention has been made in consideration of such a problem. It is therefore an object of the present invention to provide a device transferring method by which devices can be efficiently transferred from a wafer to a mounting substrate.

In accordance with an aspect of the present invention, there is provided a device transferring method for transferring a plurality of devices to a mounting substrate provided with a plurality of electrodes, the device transferring method including: a tape adhering step of adhering an expandable tape to the plurality of devices formed on a front surface side of a substrate through a buffer layer; a buffer layer breaking step of applying a laser beam of such a wavelength as to be transmitted through the substrate and to be absorbed in the buffer layer to the buffer layer from a back surface side of the substrate, to break the buffer layer, after the tape adhering step is performed; a transfer step of moving the tape in a direction for spacing away from the substrate to separate the substrate and the plurality of devices from each other, thereby transferring the plurality of devices having been formed on the substrate to the tape, after the buffer layer breaking step is performed; a tape expanding step of expanding the tape in such a manner that a layout of the plurality of devices adhered to the tape corresponds to a layout of the plurality of electrodes, after the transfer step is performed; and a die bonding step of bonding the plurality of devices adhered to the expanded tape to the plurality of electrodes at once, after the tape expanding step is performed.

Preferably, the device is an LED. In addition, preferably, the device transferring method further includes a step of exposing those surfaces of the devices which make contact with the tape, before or after the tape expanding step is performed. Besides, preferably, the tape includes a pressure sensitive adhesive including an ultraviolet (UV) curing resin, and the device transferring method further includes a step of applying UV rays to the tape to cure the pressure sensitive adhesive, after the tape expanding step is performed.

In the device transferring method according to the described aspect of the present invention, first, the plurality of devices formed on the wafer are transferred to the expandable tape. Then, the expandable tape is expanded, whereby the layout of the plurality of devices is made to correspond to the layout of the mounting positions of the devices on the mounting substrate, after which the plurality of devices are transferred to the mounting substrate at once. By this, the devices can be efficiently transferred from the wafer to the mounting substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

An embodiment of the present invention will be described below, referring to the attached drawings.FIG. 1is a perspective view depicting a configuration example of a wafer11according to the present embodiment.

The wafer11is provided with a disk-shaped substrate13having a front surface13aand a back surface13b. The substrate13is partitioned into a plurality of regions by a plurality of division lines (streets)15arranged in a grid pattern, and devices17including integrated circuits (ICs), LEDs or the like are formed respectively on the front surface13aside of the plurality of regions. The material, shape, structure, size and the like of the substrate13are not particularly limited. For example, semiconductor substrates (silicon substrate, SiC substrate, GaAs substrate, InP substrate, GaN substrate, etc.), sapphire substrates, ceramic substrates, resin substrates, metallic substrates and the like can be used as the substrate13. In addition, the kind, number, shape, structure, size, layout and the like of the devices17are also not particularly limited.

An example of a more specific configuration of the wafer11is illustrated inFIG. 2.FIG. 2is a sectional view depicting a configuration example of an optical device wafer19in which optical devices25are formed over a substrate21through a buffer layer23. A plurality of optical devices25are formed over the substrate21through a plurality of buffers23. Each of the optical devices25has a p-type semiconductor layer27formed of a p-type semiconductor in which holes are majority carriers, and an n-type semiconductor layer29formed of an n-type semiconductor in which electrons are majority carriers. The p-type semiconductor layer27and the n-type semiconductor layer29form a pn junction, whereby the optical device25capable of emitting light through recombination of holes and electrons is obtained.

The buffer layer23is configured by a layer that has a function to restrain the generation of defects due to lattice mismatch between the substrate21and the p-type semiconductor layer27, for example. The material of the buffer layer23is appropriately selected according to the lattice constants of the substrate21and the lattice constants of the p-type semiconductor layer27. In addition, the buffer layer23is a layer to be broken by application of a laser beam in a buffer layer breaking step which will be described later, and it functions also as a separation layer for separation between the substrate21and the optical devices25.

The materials of the buffer layer23, the p-type semiconductor layer27and the n-type semiconductor layer29are not limited, and any material may be freely selected insofar as the optical devices25can be formed on the substrate21. For example, by using a sapphire substrate, an SiC substrate or the like as the substrate21, the buffer layer23including GaN, the p-type semiconductor layer27including p-type GaN and the n-type semiconductor layer29including n-type GaN can sequentially be formed over the substrate21by epitaxial growth. For forming each of the layers, there can be used, for example, a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxy (MBE) method and the like. Note that while the optical device25including the p-type semiconductor layer27and the n-type semiconductor layer29has been depicted inFIG. 2, the configuration of the optical device25is not restricted to this one. For instance, an optical device25which includes a light emitting layer between a p-type semiconductor layer27and an n-type semiconductor layer29and in which light is emitted from the light emitting layer can also be used.

In the case of producing a package substrate by use of the devices17(seeFIG. 1) represented by the above-mentioned optical devices25, it is necessary to transfer the devices17from the wafer11onto a mounting substrate. While this transfer can be carried out, for example, by picking up the devices17formed on the substrate13and die-bonding them to predetermined positions of the mounting substrate, one after another, this technique needs huge working time for transferring the devices17. In the device transferring method according to the present embodiment, first, the plurality of devices17formed on the substrate13are transferred onto a tape whose shape can be expanded by an external force (an expandable tape). Then, the expandable tape is expanded to cause the layout of the plurality of devices17to correspond to the layout of the mounting positions of the devices on the mounting substrate, after which the plurality of devices17are transferred onto the mounting substrate at once. By this, the devices17can be efficiently transferred from the wafer11onto the mounting substrate.

FIG. 3is a flow chart depicting an example of the device transferring method according to the present embodiment. The device transferring method according to the present embodiment will be described below, referring toFIG. 3. Note that a case in which the optical devices25are separated from the optical device wafer19(seeFIG. 2) and transferred onto a mounting substrate will be particularly described as an example.

First, a tape adhering step S1of adhering an expandable tape to a plurality of optical devices25formed on a substrate21is performed.FIG. 4is a perspective view depicting a manner in which the optical device wafer19is adhered to a tape31. The plurality of optical devices25(seeFIG. 2) are formed on a front surface21aside of the disk-shaped substrate21. In addition, the tape31is a tape capable of being expanded (extended) by an external force (an expandable tape). An annular frame33is adhered to an outer peripheral portion of the tape31, and the plurality of optical devices25formed on the front surface21aside of the substrate21are adhered to the tape31. By this, the optical device wafer19is supported by the frame33in the state in which a back surface21bside of the substrate21is exposed to the upper side. The material of the tape31is not limited, insofar as it is expandable and it can be adhered to the plurality of optical devices25. A pressure sensitive adhesive of the tape31is preferably a material having a property of being lowered in pressure sensitive adhesive force by an external stimulus such as light or heat. For instance, a UV-curing resin can be used as the pressure sensitive adhesive of the tape31.

Next, a buffer layer breaking step S2of applying a laser beam to the buffer layer23from the back surface21bside of the substrate21to break the buffer layer23is performed. In the buffer layer breaking step S2, first, the optical device wafer19is supported by a laser processing apparatus.

FIG. 5is a perspective view depicting schematically a state in which the optical device wafer19is supported by a laser processing apparatus2. The laser processing apparatus2includes a chuck table4for holding the optical device wafer19, and a laser processing unit6capable of applying a laser beam of such a wavelength as to be transmitted through the substrate21of the optical device wafer19and to be absorbed in the buffer layer23.

The chuck table4suction holds the optical device wafer19through the tape31. Specifically, an upper surface of the chuck table4is a holding surface for holding the optical device wafer19, and the holding surface is connected to a suction source (not depicted) through a suction passage (not depicted) formed inside the chuck table4. In a state in which the frame33is fixed by clamps14(seeFIG. 6) provided in the laser processing apparatus2and the optical device wafer19is supported by the holding surface of the chuck table4, a negative pressure of the suction source is caused to act at the holding surface, whereby the optical device wafer19is suction held by the chuck table4. In addition, the chuck table4is moved in a processing feeding direction (X-axis direction) and an indexing feeding direction (Y-axis direction) by a moving mechanism (not depicted). The optical device wafer19is suction held by the chuck table4in such a manner that the back surface21bof the substrate21is exposed to the upper side. In this state, a laser beam is applied from the laser processing unit6toward the optical device wafer19.

The laser processing unit6has a cylindrical casing8. A focusing unit10for focusing a pulsed laser beam oscillated from a pulsed laser beam oscillator (not depicted) such as a yttrium aluminum garnet (YAG) laser oscillator or a yttrium orthovanadate (YVO4) laser oscillator provided in the laser processing apparatus2is attached to a tip portion of the casing8. Further, imaging means12for imaging an application region of the laser beam is attached to the casing8. An image picked up by the imaging means12is used for image processing such as pattern matching conducted for alignment between the focusing unit10and the optical device wafer19. By this, the application position of the laser beam can be controlled.

At the time of applying the laser beam to the buffer layer23(seeFIG. 2) formed on the front surface21aside of the substrate21, the chuck table4is moved to a position beneath the focusing unit10, and the laser beam of such a wavelength as to be transmitted through the substrate21and to be absorbed in the buffer layer23is focused by the focusing unit10and applied to the buffer layer23. Note that the intensity of the laser beam is set in such a manner as to make it possible to break the buffer layer23.

FIG. 6is a sectional view depicting a manner in which the laser beam is applied to the buffer layer23. The plurality of optical devices25formed on the front surface21aside of the substrate21are adhered to the tape31. In addition, the frame33is fixed by the clamps14, and the optical device wafer19is suction held by the chuck table4in such a manner that the back surface21bside of the substrate21is exposed to the upper side. When the laser beam is applied to the optical device wafer19, the laser beam is transmitted through the substrate21and absorbed in the buffer layer23, whereby the buffer layer23is broken. Note that it is unnecessary to completely separate the substrate21and the buffer layer23from each other by the application of the laser beam; specifically, it is sufficient that the buffer layer23is broken to such an extent that the substrate21and the buffer layer23can be separated from each other when the tape31is peeled off from the optical device wafer19in a later step.

Subsequently, a transfer step S3of separating the substrate21and the optical devices25from each other to thereby transfer the plurality of optical devices25formed on the front surface21aside of the substrate21onto the tape31is performed. In the transfer step S3, the tape31adhered to the optical device wafer19is peeled off. Specifically, the tape31is moved in a direction for spacing away from the substrate21. In this instance, the buffer layer23provided between the substrate21and the optical devices25has been broken in the buffer layer breaking step S2, and the joint between the substrate21and the optical devices25has been weakened. Therefore, when the tape31is moved, the optical devices25are separated from the substrate21, following up to the tape31. Note that at the time of peeling off the tape31from the optical device wafer19, a peeling member such as a cutting tool may be inserted between the substrate21and the optical device25, to promote the separation of the substrate21and the optical device25from each other. By this, the optical devices25can be separated from the substrate21, even if the breakage of the buffer layer23in the buffer layer breaking step S2is insufficient.

Next, a tape expanding step S4of expanding the tape31, to which the plurality of optical devices25have been transferred, to change the interval of the optical devices25is performed.FIG. 7Ais a plan view depicting a manner in which the tape31with the plurality of optical devices25adhered thereto is expanded. Since the tape31is expandable, it can be expanded by exerting an external force thereon. When the tape31is expanded, the distance between the adjacent optical devices25is enlarged, whereby the layout of the plurality of optical devices25is changed.FIG. 7Bis a plan view depicting the tape31after expanded. As illustrated inFIG. 7B, when the tape31is expanded, the interval of the optical device25is widened according to the amount of expansion of the tape31.

The plurality of optical devices25adhered to the tape31are mounted in a predetermined layout onto the mounting substrate in a later step. In view of this, in the tape expanding step S4, the tape31is expanded in such a manner that the layout of the optical devices25adhered to the tape31corresponds to the layout of the optical devices25on the mounting substrate. For instance, in the case where the plurality of optical devices25adhered to the tape31are to be connected to a plurality of electrodes provided in a predetermined layout on the mounting substrate, the tape31is expanded in such a manner that the layout of the optical devices25adhered to the tape31corresponds to the layout of the plurality of electrodes. Note that the expression “the layout of the plurality of optical devices25corresponds to the layout of the plurality of electrodes” refers to a state in which the plurality of optical devices25are laid out at such an interval that they can be connected respectively to desired electrodes. For example, it is sufficient to expand the tape31in such a manner that the interval of the plurality of optical devices25adhered to the tape31will be substantially the same as the interval of the plurality of electrodes formed on the mounting substrate.

The method for expanding the tape31is not limited, and the expansion can be carried out by use of an exclusive-use expanding apparatus or the like. For example, the expansion can be carried out by use of an expanding apparatus which includes a support unit for supporting an outer peripheral portion of the tape31, and a contact portion to be brought into contact with the side of the back surface (the surface on which the optical devices25are not formed) of the tape31. In this case, in a state in which the outer peripheral portion of the tape31is supported by the support unit, a central portion on the back surface side of the tape31is brought into contact with the contact portion, and the contact portion is relatively moved from the back surface side toward the front surface side of the tape31, whereby the tape31can be expanded. Note that a manner in which the tape31is expanded with the frame33(seeFIG. 4, etc.) detached from the tape31is illustrated inFIGS. 7A and 7B, but the expansion of the tape31may be conducted with the frame33adhered to the tape31. For example, the expansion of the tape31can be carried out in a state in which the frame33adhered to the tape31is supported by the support unit of the above-mentioned expanding apparatus.

After the tape expanding step S4, a treatment for lowering the pressure sensitive adhesive force of the tape31is preferably performed, to thereby facilitate the peeling of the optical devices25from the tape31in a later step. For instance, in the case where the pressure sensitive adhesive of the tape31is a UV curing resin, the pressure sensitive adhesive force of the tape31can be lowered by performing a step of applying UV rays to the tape31to thereby cure the pressure sensitive adhesive of the tape31.

Subsequently, a die bonding step S5of transferring, and bonding, the plurality of optical devices25adhered to the expanded tape31onto the mounting substrate at once is performed. In the die bonding step S5, the plurality of optical devices25adhered to the tape31are transferred and mounted onto the mounting substrate while maintaining the layout of the plurality of optical devices25. Therefore, it is unnecessary to perform the alignment between the plurality of optical devices25and the mounting substrate on the basis of each optical device25, and the devices can be efficiently transferred from the tape31onto the mounting substrate. The method for transferring the plurality of optical devices25onto the mounting substrate is not particularly limited. For instance, a transfer unit by which the plurality of optical devices25are picked up from the tape31and transferred onto the mounting substrate at once may be used, or the plurality of optical devices25may be transferred onto the mounting substrate by adhering the tape31directly to the mounting substrate.

The method of transferring the plurality of optical devices25onto the mounting substrate by a transfer unit will be described referring toFIGS. 8 and 9.FIG. 8is a perspective view depicting a manner in which a plurality of optical devices25are held by a transfer unit20. The transfer unit20includes a plate-shaped base22, and a plurality of suction pads24that are provided on a lower surface side of the base22and that suction hold the optical devices25.

First, the tape31is held horizontally such that the plurality of optical devices25are exposed to the upper side, and the transfer unit20is disposed on an upper side of the tape31. Then, the transfer unit20is moved vertically downward, to bring the plurality of suction pads24into contact with the optical devices25, respectively. In this state, the plurality of optical devices25are suction held by the plurality of suction pads24, whereby the plurality of optical devices25are held by the transfer unit20. Thereafter, with the tape31maintained in situ, the transfer unit20is moved vertically upward, whereby the plurality of optical devices25are peeled off from the tape31, and are picked up by the transfer unit20. As a result, those surfaces of the optical devices25which have been in contact with the tape31are exposed. The plurality of suction pads24are laid out such as to correspond to the layout of the plurality of optical devices25adhered to the tape31. Specifically, the interval of the plurality of suction pads24is substantially coincident with the interval of the plurality of optical devices25adhered to the tape31. By use of the transfer unit20, therefore, the plurality of optical devices25can be picked up at once.

Thereafter, the transfer unit20is moved onto the mounting substrate which is the destination for the plurality of optical devices25to be transferred.FIG. 9is a perspective view depicting a manner in which the plurality of optical devices25are disposed on a mounting substrate35by the transfer unit20. The mounting substrate35is formed with a plurality of electrodes to which the optical devices25are to be connected respectively. Here, an example is depicted in which the optical devices25are red LEDs, whereas the mounting substrate35is formed with a plurality of electrodes37R to be connected with the red LEDs, a plurality of electrodes37G to be connected with green LEDs, and a plurality of electrodes37B to be connected with blue LEDs.

First, the mounting substrate35is disposed at a predetermined position, and an adhesive such as a silver paste is applied onto the plurality of electrodes37R. Then, the transfer unit20is positioned in such a manner that the suction pads24are disposed respectively on the upper side of the plurality of electrodes37R. Thereafter, the transfer unit20is moved vertically downward, whereby those surfaces of the plurality of optical devices25which have been in contact with the tape31are connected respectively to the electrodes37R through the adhesive. In this way, the plurality of optical devices25are bonded to the mounting substrate35. Note that the plurality of suction pads24are provided in such a manner that the layout thereof corresponds to the layout of the plurality of electrodes37R. By use of the transfer unit20, therefore, the plurality of optical devices25can be bonded to the mounting substrate35at once.

FIG. 10is a perspective view depicting the mounting substrate35to which a plurality of optical devices25are bonded. The optical devices25which are the red LEDs are bonded respectively to the plurality of electrodes37R (seeFIG. 9) provided on the mounting substrate35. Then, a step of bonding green LEDs respectively to the plurality of electrodes37G at once and a step of bonding blue LEDs respectively to the plurality of electrodes37B at once are performed, whereby an LED package in which the LEDs for three colors are mounted can be produced.

Note that in the case of transferring the optical devices25by use of the transfer unit20, the side of those surfaces (back surfaces) of the optical device25which have been in contact with the tape31is connected to the electrodes, but the side of those surface (front surfaces) of the optical devices25which have not been in contact with the tape31may also be connected to the electrodes. An example of the method of connecting the front surface side of the optical devices25to the electrodes formed on the mounting substrate35is illustrated inFIG. 11.

FIG. 11is a perspective view depicting a manner in which a plurality of optical devices25are mounted onto a mounting substrate35by use of a roller26. At the time of mounting the plurality of optical devices25onto the mounting substrate35by use of the roller26, first, the mounting substrate35is disposed at a predetermined position, an adhesive such as a silver paste is applied to the electrodes formed on the mounting substrate35, and a front surface31a(a surface on which the plurality of optical devices25are formed) of the expanded tape31and the surface formed with the electrodes of the mounting substrate35are made to face each other. In this instance, the tape31and the mounting substrate35are positioned in such a manner that the plurality of optical devices25are respectively disposed on the upper side of the plurality of electrodes (inFIG. 11, electrodes37R). Thereafter, the roller26is rotated in a direction indicated by arrow A, and a back surface31b(a surface on which the optical devices25are not formed) of the tape31is pressed to the mounting substrate35side by the roller26. By this, the plurality of optical devices25are respectively connected to the electrodes37R through the adhesive, and are bonded to the mounting substrate35.

Note that as the adhesive for adhering the electrodes37R and the optical devices25to each other, an adhesive having an adhesive force higher than the adhesive force of the tape31is used. The aforementioned treatment for lowering the adhesive force of the tape31(application of UV rays or the like) ensures that the adhesive force required of the adhesive applied to the electrodes37R is lowered, thereby making it possible to enhance the degree of freedom in selecting the material of the adhesive. Thereafter, the tape31is peeled off from the mounting substrate35, whereby the plurality of optical devices25and the tape31are separated from each other, and a mounting substrate35with the plurality of optical devices25bonded thereto is obtained (seeFIG. 10).

As above-mentioned, in the device transferring method according to the present embodiment, after the plurality of optical devices25are adhered to the expandable tape31, the tape31is expanded, whereby the layout of the plurality of optical devices25can be controlled in such a manner that the layout of the plurality of optical devices25adhered to the tape31corresponds to the layout of the mounting positions of the optical devices25on the mounting substrate35. By this, the plurality of optical devices25can be transferred onto the mounting substrate35at once, and the transfer of the devices can be performed efficiently. Particularly, at the time of producing, for example, LED packages in which a multiplicity of LEDs are arranged at predetermined periods on a mounting substrate, the efficiency of the device transferring work is largely enhanced if the plurality of devices formed on the same wafer can be disposed onto a mounting substrate at a predetermined interval and at once. For this reason, the device transferring method according to the present embodiment is especially useful for the case of, for example, transferring a plurality of LEDs onto a mounting substrate to produce LED packages. In addition, in the device transferring method according to the present embodiment, the expandable tape31is expanded to widen the interval of the plurality of optical devices25, before picking up the devices. Therefore, breakage of the optical devices25due to contact between the optical devices25at the time of picking up can be prevented, and an enhanced yield can be realized.

Note that while an example in which all the optical devices25adhered to the tape31are transferred onto the mounting substrate35at once has been depicted in the above embodiment, all the optical devices25may be transferred by repeating the die bonding step S5multiple times. In other words, an operation of transferring part of the plurality of optical devices25adhered to the tape31onto the mounting substrate35may be repeated plural times to thereby transfer all the optical devices25. Besides, in the case of repeating the die bonding step S5multiple times, the tape expanding step S4may be again carried out after the die bonding step S5is performed. In other words, after part of the plurality of optical devices25adhered to the tape31are transferred onto the mounting substrate35at once, the tape31may be expanded to again adjust the layout of the remaining optical devices25, before performing the next transferring operation. Particularly, in the case where it is difficult to lay out all the optical devices25at desired positions by one-time expansion of the tape31due to the influence of, for example, variability of the amount of expansion of the tape31, it is desirable to divisionally perform the transfer of the optical device25in multiple steps, while conducting the tape expanding step S4each time, to adjust the layout of the optical devices25. By this, the interval of the optical devices25can be controlled accurately, and the optical devices25can be easily arranged at desired positions on the mounting substrate35.

In addition, at the time of adhering the optical devices25onto the mounting substrate35, the adhesion surfaces of the optical devices25can be changed as required. Specifically, either of the side of the surfaces making contact with the tape31(back surfaces) and the side of the surfaces not making contact with the tape31(front surfaces) of the optical devices25depicted inFIG. 7Bmay be adhered to the mounting substrate35. In the case of changing the adhesion surfaces of the optical devices25, a step of altering the exposed surfaces of the optical devices25is conducted before the die bonding step S5. For example, by using the method illustrated inFIGS. 8 and 9, after the tape expanding step S4, the back surface side of the optical devices25can be exposed and the back surface side of the optical devices25can be adhered to the mounting substrate. InFIG. 9, the front surface side of the optical devices25is suction held by the suction pads24, whereas the back surface side is exposed.

Besides, the back surface side of the optical devices25may be exposed by re-adhering the tape prior to the tape expanding step S4. Specifically, before the tape31with the plurality of optical devices25adhered thereto is expanded (seeFIG. 7A), a re-adhering tape is adhered to the front surface side of the plurality of optical devices25. Thereafter, the tape31is peeled off to separate the plurality of optical devices25and the tape31from each other, whereby the plurality of optical devices25are transferred onto the re-adhering tape, in the state in which their back surface side is exposed. In this case, the layout of the optical devices25is changed by expanding the re-adhering tape in the tape expanding step S4to be conducted later, and, therefore, an expandable tape is used as the re-adhering tape. In addition, in the case of using the re-adhering tape, the tape31may not necessarily be expandable.

Besides, while the case where the optical devices25formed over the substrate21through the buffer layer23are transferred has been mainly described hereinabove, the kind of the devices to be transferred by the device transferring method according to the present embodiment is not restricted. In addition, the material of the buffer layer23also can be selected as required, insofar as the buffer layer23can be broken by the application of the laser beam in the buffer layer breaking step S2.

Other than the above-mentioned, the structures and the methods and the like according to the present embodiment can be appropriately modified in carrying out the present invention, without departing from the scope of the object of the invention.