TW201724551A - Method of mounting light-emitting element - Google Patents

Abstract

The present invention provides a method of mounting a light-emitting element, including: employing epitaxial growth to grow and form a first semiconductor layer, an active layer, a second semiconductor layer and a buffer layer successively on a starting substrate using a material that is lattice-matched to the starting substrate; employing epitaxial growth to form, on the buffer layer, a window layer/support substrate using a material that is not lattice-matched to the starting substrate; removing the starting substrate; forming a first ohmic electrode on the first semiconductor layer; forming a partial removed portion exposing the second semiconductor layer, the buffer layer or the window layer/support substrate, to provide a step; forming a second ohmic electrode in the removed portion; fabricating a light-emitting element chip by separating a light-emitting element in which the first and second ohmic electrodes are formed; and flip-mounting the light-emitting element chip onto a mounting substrate in such a way that the side of the light-emitting element chip on which the first and second ohmic electrodes are formed is closest to the mounting substrate.

Description

Light-emitting component mounting method

The present invention relates to a method of mounting a light-emitting element, and more particularly to a method of mounting a light-emitting element in which a light-emitting element wafer is flip-chip mounted on a mounting substrate.

Products such as Chip On Board (COB) are excellent in heat dissipation properties of LED elements, and thus are used as an LED chip mounting method for applications such as illumination. In the case where an LED is mounted on a COB or the like, it is necessary to directly bond the wafer to the flip chip mounting system of the board. In the case where the LED element is mounted on a flip chip, there is a method of Au-Au bonding by ultrasonic, eutectic soldering or the like.

When a flip chip mounted wafer is produced by a yellow to red LED, an AlGaInP-based material is used for the light-emitting layer. Since the AlGaInP-based material does not have a crystal ingot, and the LED portion is formed by the epitaxial method, the starting substrate is selected to be a material different from AlGaInP. Most of the starting substrates are GaAs or Ge. Since these substrates have light absorption characteristics for visible light, the starting substrate is removed in the case of fabricating a flip chip mounted wafer.

However, since the epitaxial layer forming the light-emitting layer is a very thin film, it cannot be stored independently after removing the starting substrate (JC: Please correct it in its entirety). Therefore, it is necessary to replace the starting substrate with a function of having a function as a window layer in which the light-emitting layer is slightly transparent to the light-emitting wavelength, and having a function as a support substrate having a sufficient thickness for independence.

As described above, since the AlGaInP-based material does not have a crystal ingot, GaP, GaAsP, sapphire, or the like is selected as a material having the function of the above-described window layer and supporting substrate. Regardless of which material is selected, the mechanical properties such as the coefficient of thermal expansion or the Young's modulus are different from those of the AlGaInP system because of the difference from AlGaInP.

By the Au-Au bonding of the ultrasonic wave, as described in Non-Patent Document 1, it is difficult to support the wafer without tilting, and it is difficult to efficiently propagate the ultrasonic wave to the wafer, and the wafer may be damaged when the ultrasonic wave propagates. .

In order to solve the above problems, a technique of forming AuSn eutectic bumps and bonding to a substrate by heat fusion (reflow temperature of 211 to 280 ° C) has been disclosed. The eutectic method is less likely to cause physical damage accompanying ultrasonic waves than the ultrasonic method. However, during the melting and solidification of the eutectic solder, the eutectic metal itself thermally shrinks. As a result, stress occurs in the vicinity of the interface of the semiconductor side where the eutectic metal is in contact with the LED, and this stress causes a problem of wafer destruction.

Further, the difference in thermal expansion coefficient between the material of the window layer and the support substrate and the material difference of the AlGaInP light-emitting layer also causes a problem due to the above-described heat-melting step. That is, for the coefficient of linear expansion of the AlGaInP-based material of 5.4E-6 [/k], the coefficient of linear expansion of GaP is 4.5E-6 [/k], and the coefficient of linear expansion of sapphire is 7.0E-6 [/k]. Therefore, in the case where the window layer and the support substrate are GaP when mounted by the heat fusion treatment, compressive stress is generated in the AlGaInP light-emitting layer, and tensile stress is generated in the window layer and the support substrate. In the case where the AlGaInP light-emitting layer is sapphire, a tensile stress is generated in the AlGaInP light-emitting layer, and a compressive stress is generated in the window layer and the support substrate. This stress can also cause wafer damage.

At the time of flip chip mounting, the surfaces formed on the first and second ohmic electrode sides of the light-emitting element wafer press the mounting substrate side. At this time, although the metal portion on the mounting surface side is deformed by the pressing of the light-emitting element wafer, the light-emitting element wafer sinks on the mounting surface side, but this deformation is not large. Therefore, in the case where the step difference between the first ohmic electrode and the second ohmic electrode on the light-emitting element wafer provided on the mounting surface is large, the amount of deformation of the metal of the first ohmic electrode that is in contact with the mounting surface is insufficient, although the first ohm is The electrode surface is in sufficient contact with the mounting surface, but the phenomenon that the second ohmic electrode surface is not in contact with the mounting surface occurs. As a result, a short circuit occurs, and there is a problem that it cannot be installed. Therefore, in general, bumps are provided on the first ohmic electrode and the second ohmic electrode to increase the amount of deformation of the electrode. However, the bumps must be formed thickly by Au (gold) or the like using a gold plating method or the like, and the material cost becomes extremely expensive. [Prior Technical Literature] [Non-Patent Literature]

[Non-Patent Document 1] Nikkei Electronics, Nikkei BP, February 11, 2008

[Problems to be Solved by the Invention] In view of the foregoing problems, the present invention provides a method of mounting a light-emitting element, which can suppress breakage of a flip-chip mounting accompanying the use of ultrasonic waves, and can suppress flip-chip bonding using eutectic soldering. Further, in the case of stress destruction due to heat shrinkage during mounting, even in the case where the step difference between the first ohmic electrode and the second ohmic electrode is large, the mounting of the light-emitting element wafer can be easily performed. [Technical means to solve the problem]

In order to achieve the above object, a method for mounting a light-emitting element according to the present invention includes the steps of: growing on a starting substrate by a crystal lattice matching with the starting substrate, by epitaxial growth, Forming a first semiconductor layer, an active layer, a second semiconductor layer, and a buffer layer; forming a window layer on the buffer layer by epitaxial growth on a material that is an amorphous matching system for the starting substrate And supporting the substrate; removing the starting substrate; forming a first ohmic electrode on the first semiconductor layer; and partially forming a removing portion for exposing the second semiconductor layer, the buffer layer or the window layer and the supporting substrate Providing a step difference; forming a second ohmic electrode in the removing portion; separating the light emitting element formed by the first and second ohmic electrodes to form a light emitting element wafer; and mounting the light emitting element wafer on the mounting substrate The side of the light-emitting element wafer on which the first and second ohmic electrodes are formed is set to the mounting substrate side.

In this way, by forming the window layer and supporting the substrate by epitaxial growth, a large number of rows are inserted into the window layer and the supporting substrate, and when the stress is applied to the wafer during ultrasonic mounting, the window layer is used. The supporting substrate is deformed along the difference surface, and stress cracking of the wafer can be suppressed. Further, in the flip chip mounting using the eutectic metal, in the shrinkage at the time of returning to the room temperature due to the expansion of the heating, the substrate supported by the window layer is deformed along the difference surface, and can be suppressed. Stress damage of the wafer. Further, even when the step difference between the first ohmic electrode and the second ohmic electrode is large, breakage of the light-emitting element at the time of flip chip mounting can be prevented, and mounting of the light-emitting element wafer can be easily performed.

In this case, the first semiconductor layer, the active layer, and the second semiconductor layer are preferably AlGaInP or AlGaAs.

As such, as the first semiconductor layer, the active layer, and the second semiconductor layer, materials similar to those described above can be suitably used.

Furthermore, at this time, it is preferable that the window layer and the supporting substrate are GaP or GaAsP.

In this way, as the window layer and the support substrate, the above-described material is used, and the window layer is suitable, and the stress crack of the wafer can be surely suppressed at the time of flip chip mounting.

Further, at this time, the step difference between the first ohmic electrode and the second ohmic electrode may be 3 μm or more and 11 μm or less.

As a result, even if the step difference between the first ohmic electrode and the second ohmic electrode is as large as described above, the effect can be sufficiently exerted. [Compared with the efficacy of prior art]

In the method of mounting a light-emitting device of the present invention, a window layer and a support substrate are formed by epitaxial growth, and a large number of rows are inserted into the window layer and the support substrate, and when stress is applied to the wafer during ultrasonic mounting, By the window layer and the supporting substrate, the substrate is deformed along the difference surface, and the stress damage of the wafer can be suppressed. In the flip chip mounting using the eutectic metal, the shrinkage is returned to the room temperature due to the expansion of the heating. Among them, the substrate supported by the window layer is deformed along the difference surface, and stress cracking of the wafer can be suppressed. Further, even when the step difference between the first ohmic electrode and the second ohmic electrode is large, breakage of the light-emitting element at the time of flip chip mounting can be prevented, and mounting of the light-emitting element wafer can be easily performed.

Hereinafter, embodiments of the invention will be described, but the invention is not limited thereto. As described above, there is a problem in that the wafer of the light-emitting element is broken at the time of flip chip mounting. Here, the inventors of the present invention have diligently studied in order to solve such problems. As a result, it was found that by epitaxially growing the window layer and supporting the substrate with the amorphous lattice matching material of the starting substrate, it was found that a large number of rows were inserted into the window layer and the supporting substrate. Accordingly, it has been found that it is possible to suppress the destruction of the wafer during the ultrasonic mounting and the flip-chip mounting using the eutectic metal, and further, even in the case where the step difference between the first ohmic electrode and the second ohmic electrode is large, It is easy to mount the light-emitting element wafer while preventing breakage of the light-emitting element at the time of flip chip mounting.

Hereinafter, a method of attaching the light-emitting element of the present invention will be described with reference to Figs. 1 to 8 .

First, the starting substrate 101 (SP1 of Fig. 1) as shown in Fig. 2 is prepared. As the starting substrate 101, it is preferable to use the starting substrate 101 whose crystal axis is inclined in the [001] direction toward the [110] direction. Further, as the starting substrate 101, GaAs or Ge can be suitably used. In this manner, since the material of the active layer 104 to be described later can be epitaxially grown by the lattice matching system, the quality of the active layer 104 can be easily improved, and the luminance can be improved or the life characteristics can be improved.

Next, a selective etching layer 102 (SP2 of FIG. 1) may be formed on the starting substrate 101. The selective etching layer 102 is formed on the starting substrate 101 and can be grown by, for example, MOVPE method (organic metal vapor phase growth method), MBE (molecular line epitaxy method), or CBE (chemical line epitaxy method).

The selective etching layer 102 is formed of a layer structure of two or more layers, and at least the second selective etching layer 102A that is in contact with the starting substrate 101 and the first selective etching layer 102B that is in contact with the first semiconductor layer 103 to be described later are preferable. . The second selective etch layer 102A and the first selective etch layer 102B are preferably formed from different materials or compositions.

Next, the starting substrate 101 is grown by epitaxial growth, and the light emitted by the first semiconductor layer 103 of the first conductivity type, the active layer 104, and the second semiconductor layer 105 of the second conductivity type is sequentially formed. Portion 108 and buffer layer 106 (SP3 in Fig. 1).

The first semiconductor layer 103, the active layer 104, and the second semiconductor layer 105 are preferably AlGaInP or AlGaAs. Thus, the material as described above can be suitably used as the first semiconductor layer, the active layer, and the second semiconductor layer.

Further, it is preferable to form the buffer layer 106 with InGaP.

In order to improve the characteristics of the first semiconductor layer 103 or the second semiconductor layer 105, it is common to include a plurality of layers in each layer. Needless to say, the first semiconductor layer 103 or the second semiconductor layer 105 is not limited to a single one. layer.

At this time, the first semiconductor layer 103 may be composed of a structure of two or more layers. The low Al composition layer 103A on the side of the first semiconductor layer 103 to be subjected to the surface roughening treatment described later can be formed by a material having a small Al composition as compared with the high Al composition layer 103B on the active layer side.

In this way, while maintaining the effect of the carrier of the cladding layer, the mechanical strength of the pad electrode due to over-etching and the wafer breakage occurring during wire bonding are suppressed, and the roughness of the desired roughness can be manufactured. Surface light-emitting elements.

Next, on the buffer layer 106, a window layer and a support substrate 107 are formed by epitaxial growth on the starting substrate 101 by an amorphous matching system, thereby forming an epitaxial substrate 109 (Fig. 1). SP4). As the window layer and supporting substrate 107, GaP or GaAsP is preferred.

Next, the starting substrate 101 and the second selective etching layer 102A are removed from the epitaxial substrate 109. As shown in FIG. 3, only the first selective etching layer 102B remains on the surface of the first semiconductor layer 103 of the light emitting element substrate 110 ( SP5 of Fig. 1). Specifically, the first selective etching layer 102B remains on the surface of the first semiconductor layer 103 from the epitaxial substrate 109 by using the second selective etching layer 102A and removing the starting substrate 101 by wet etching. .

Next, as shown in FIG. 4, the first ohmic electrode 121 for supplying a potential to the light-emitting element is formed on the surface of the first selective etching layer 102B on the first semiconductor layer 103 (SP6 of Fig. 1).

Next, as shown in FIG. 4, the first selective etching layer 102B (SP7 of FIG. 1) in a range other than the bottom of the first ohmic electrode 121 is removed. Specifically, by using the first ohmic electrode 121 as an etch mask, the first selective etch layer 102B in a range other than the bottom of the first ohmic electrode 121 can be removed by etching.

Next, as shown in FIG. 5, the first surface roughening treatment step can be performed, and at least a portion other than the formation portion of the first ohmic electrode 121 on the surface of the first semiconductor layer 103 is surface roughened ( SP8 of Fig. 1).

Specifically, for example, a first surface roughening liquid composed of a mixed solution of a mineral acid and an organic acid can be used, and the first portion of the first ohmic electrode 121 on the surface of the first semiconductor layer 103 is first formed. Surface roughening treatment.

Next, as shown in FIG. 6, a step of partially forming a removal portion 170 for exposing the second semiconductor layer, the buffer layer, or the window layer-supporting substrate is performed (the removal portion and the step difference forming step, FIG. 1) SP9). As shown in Fig. 6, a step is provided between the removal portion 170 and the non-removed portion 180 other than the removal portion 170.

Specifically, for example, etching can be performed from the first semiconductor layer of the range 140 to a portion of the window layer supporting substrate by the ICP dry etching method having low material selectivity. As a result, a portion (removed portion 170) in which the window layer and the support substrate 107 are exposed as shown in Fig. 6 can be formed. The removing portion 170 inherits the surface rough pattern formed by the first surface roughening treatment step and has a surface roughness pattern.

Next, as shown in FIG. 7, the second ohmic electrode 122 (SP10 of the first drawing) is formed on the surface of the window layer-supporting substrate 107 of the removing portion 170. As a result, the first ohmic electrode 121 and the second ohmic electrode 122 are formed with a step difference. In the present invention, for example, the step difference between the first ohmic electrode 121 and the second ohmic electrode 122 can be 3 μm or more and 11 μm or less. As described above, even if the step difference between the first ohmic electrode and the second ohmic electrode is large, as described later, it is possible to easily mount the light-emitting element wafer while preventing breakage of the light-emitting element at the time of flip chip mounting.

Next, as shown in FIG. 7, the surface of the first semiconductor layer 103 and at least a part of the side surface of the light-emitting portion 108 can be covered by the insulating protective film 150 (SP11 of Fig. 1). The insulating protective film 150 may be any material if it is transparent and has an insulating property. As the insulating protective film 150, for example, SiO is used. _­ Or SiN _x is suitable. In this case, the opening processing can be easily performed on the tops of the first ohmic electrode 121 and the second ohmic electrode 122 by the photolithography method and the etching solution containing the hydrofluoric acid.

Next, a step of separating the light-emitting elements in which the first and second ohmic electrodes 121 and 122 are formed to form a light-emitting element wafer is performed (SP12 in FIG. 1). Specifically, the scribe line can be scribed along the scribed range 142 (refer to FIG. 7), and the light-emitting element can be separated by performing a breaking to produce the light-emitting element wafer 1 (die).

Next, as shown in Fig. 8, the second surface roughening treatment step can be performed by the second surface roughening liquid, and the side surface and the reverse surface of the window layer and the support substrate 107 can be roughened. Further, since the light-emitting angle is enlarged by the second surface roughening treatment, the processing may not be performed when the light-emitting angle is not desired to be enlarged.

Next, a step of flip-chip mounting the light-emitting device wafer on the mounting substrate (SP14 in FIG. 1) is performed, and a side on which the first and second ohmic electrodes are formed on the light-emitting element wafer 1 is a mounting substrate ( Side not shown).

[First Embodiment] In the above-described flip chip mounting step (SP14), in the first embodiment, after the crystal substrate of the mounting substrate (mounting plate) is mounted, the flip chip bonding can be performed by ultrasonic bonding. . At this time, the mounting joint portion of the first ohmic electrode is provided at the edge portion of the wafer.

In the first embodiment, in the case of ultrasonic installation, since the ultrasonic wave propagates in a single crystal portion other than the sliding surface (through the differential surface), it is efficiently performed, and on the other hand, from the top. When the wafer is pressed, the window layer and the supporting substrate portion are easily deformed along the sliding surface, and are not easily broken.

[Second Embodiment] Among the above-described flip chip mounting step (SP14), in the second embodiment, as a structure in which a eutectic metal is further laminated on the first ohmic electrode and the second ohmic electrode, crystal After the grain bonding, the flip chip can be mounted by transmission heating and cooling treatment.

The eutectic solder layer of AuSn or the like having a low melting point on the first ohmic electrode and the second ohmic electrode, and the window layer and the supporting substrate are a flip chip structure having a high density of the through-difference. In the second embodiment, in the heat shrinkage of the eutectic soldering, although the pulling stress is applied to the window layer and the supporting substrate, the sliding surface (through the differential surface) has a larger deformation than the single crystal, and the stress is greater. Not concentrated, but can avoid wafer damage.

In this way, the window layer and the supporting substrate are epitaxially grown by the material of the amorphous integrated layer of the starting substrate, and a large number of rows are inserted into the window layer and the supporting substrate (the difference density is 10 pieces/cm 2 or more). ). When the window layer and the support substrate have a high density difference, when the flip chip is mounted by ultrasonic waves (the first embodiment), when the stress is applied to the wafer, the substrate is supported by the window layer. The differential surface is deformed, and the damage of the wafer can be suppressed. Further, in the flip chip mounting using the eutectic metal (second embodiment), in the shrinkage at the time of returning to room temperature due to the expansion of the heating, the substrate is supported by the window layer along the difference surface. The deformation can suppress the breakage of the wafer.

Further, as in the case where the removal portion is formed in the present invention and the step is set, even when the step difference between the first ohmic electrode and the second ohmic electrode is large, when the light-emitting element wafer is pressed during the flip-chip mounting, the light-emitting element wafer is Due to the deformation, it is possible to prevent breakage of the light-emitting element during flip chip mounting. In particular, the window layer and the support substrate have a sliding surface, and the light-emitting element wafer is easily deformed by pressing, and the second ohmic electrode 122 is in contact with the mounting surface while the second ohmic electrode 122 is in contact with the mounting surface. Bumps are not necessarily required in flip chip mounting. Thereby, the mounting of the light-emitting element wafer can be easily performed.

Specifically, the step difference between the first ohmic electrode and the second ohmic electrode is as described above, and can be 3 μm or more and 11 μm or less. In this way, even if the step difference between the first ohmic electrode and the second ohmic electrode is large, the present invention can sufficiently exert its effects.

The present invention will be more specifically described below with reference to examples and comparative examples of the invention, but the invention is not limited thereto.

[Examples] On the starting substrate 101 made of n-type GaAs having a thickness of 280 μm which was inclined by 15° from the [001] direction to the [110] direction, the MOVPE method (organic metal vapor phase growth method) was used. The GaAs buffer layer (not shown) is grown to 0.5 μm, the second selective etch layer 102A composed of the n-type AlInP layer is grown to 1 μm, and the first selective etch layer 102B composed of the n-type GaAs layer is grown to 1 μm. Thereafter, the light-emitting portion 108 composed of the n-type cladding layer (first semiconductor layer 103) composed of AlGaInP, the active layer 104, and the p-type cladding layer (second semiconductor layer 105) is formed to have a thickness of 5.5 μm. On the other hand, the buffer layer 106 made of p-type GaInP was formed to be 0.3 μm, and a part of the window layer and the support substrate 107 made of p-type Gap was grown by 1.0 μm. Then, it is transferred to the HVPE furnace, and the window layer-support substrate 107 composed of the p-type GaP is grown by 120 μm to obtain an epitaxial substrate 109 (see FIG. 2).

Next, the starting substrate 101, the GaAs buffer layer, and the second selective etching layer 102A are etched away from the epitaxial substrate 109, and the light-emitting element substrate 110 in which only the first selective etching layer 102B remains is produced (refer to FIG. 3). . Specifically, from the epitaxial substrate 109, the second selective etching layer 102A is used as a selective etching layer, and the starting substrate 101 is removed by wet etching to form the light-emitting element substrate 110.

Next, the first ohmic electrode 121 for the potential supply electrode of the light-emitting element is formed. Specifically, as shown in FIG. 4, the first ohmic electrode 121 is formed on the first selective etching layer 102B of the light-emitting element substrate 110. Then, the first ohmic electrode 121 is used as a mask, and the first selective etching layer 102B in the range other than the first ohmic electrode 121 is removed by etching.

Next, as shown in FIG. 9, the photoresist mask 123 is provided in the second ohmic electrode formation predetermined range 122a by the photolithography method, and the first surface roughening treatment is performed by the first surface roughening liquid. The first surface roughening liquid was prepared by mixing a mixture of acetic acid and hydrochloric acid, and was roughened by etching at room temperature for 1 minute.

Next, an open pattern is formed in the range 140 (refer to FIG. 9) by the photolithography method, and the removing portion and the step forming step are performed by the ICP plasma etching method containing hydrochloric acid gas, and the light emitting portion 108 is removed. The buffer layer 106 forms a removal portion 170 that exposes the window layer and the support substrate 107, and a non-removed portion 180 (refer to FIG. 10). At this time, although the removal portion 170 inherits the surface roughness pattern formed in the first surface roughening treatment step, the portion of the second ohmic electrode forming portion 141 does not form a rough surface in the first surface roughening treatment step. It does not become a surface rough pattern and is formed into a flat surface.

Next, the second ohmic electrode 122 is formed in the forming portion 141 of the second ohmic electrode of FIG. 10 (refer to FIG. 11). Next, the laminate formed by the SiO ₂ insulating protective film 150, and the cover is protected by the SiO ₂ insulating film composed of the side surface of the first semiconductor layer 103 and the surface 150 of the light emitting portion 108 to be formed.

Next, the scribe line is scribed along the scribed range 142, the crack line is extended along the scribe line, and then the element is separated by performing the cleavage to form the light-emitting element wafer 11.

After the light-emitting element wafer 11 is formed, the light-emitting element wafer 11 is transferred onto the support tape so that the surface on which the first ohmic electrode 121 is provided is the side of the tape surface, and then the surface roughening window layer is formed by the second surface roughening liquid. The second surface roughening treatment step of the side surface and the back surface of the support substrate 107 (refer to Fig. 12). As the second surface roughening liquid, a mixed liquid of acetic acid, hydrofluoric acid, and iodine was produced. Then, the second surface roughening treatment was performed by etching at room temperature for 1 minute.

[Comparative Example] An n-type GaAs buffer layer was not formed by the MOVPE method on a starting substrate 301 made of n-type GaAs having a thickness of 280 μm which was inclined by 15° from the [001] direction to the [110] direction. The second selective etching layer 302A composed of the n-type AlInP layer is grown to 1 μm, and the first selective etching layer 302B composed of the n-type GaAs layer is grown to 1 μm, and has a second option. On the selective etching layer 302 of the etching layer 302A and the first selective etching layer 302B, an n-type cladding layer (first semiconductor layer 303) composed of AlGaInP, an active layer 304, and a p-type cladding layer (second semiconductor layer) 305) The light-emitting portion 308 is formed to have a thickness of 5.5 μm, and a buffer layer 306 made of p-type GaInP is formed to be 0.3 μm, and the current diffusion layer 307 is epitaxially grown by 1.0 μm. Epitaxial substrate 309 (refer to Fig. 13).

Next, as shown in Fig. 14, a GaP single crystal substrate 310 having a thickness of 300 μm is bonded to the epitaxial substrate 309. The epitaxial wafer 309 is bonded to the GaP single crystal substrate 310, and both the epitaxial substrate 309 and the GaP single crystal substrate 310 are washed with an alkali solution, and bonded by a BCB adhesive.

Next, the starting substrate 301, the GaAs buffer layer, and the second selective etching layer 302A are etched away from the epitaxial substrate 309, and the light-emitting element substrate 311 in which only the first selective etching layer 302B remains is produced (refer to Fig. 15). . Specifically, from the epitaxial substrate 309, the second selective etching layer 302A is used as a selective etching layer, and the starting substrate 301 is removed by wet etching to form the light-emitting element substrate 311.

Next, the first ohmic electrode 321 for the potential supply electrode of the light-emitting element is formed. Specifically, as shown in FIG. 16, the first ohmic electrode 321 is formed on the first selective etching layer 302B of the bonding substrate 311. Then, the first ohmic electrode 321 is used as a mask, and the first selective etching layer 302B in a range other than the first ohmic electrode 321 is removed by etching.

Next, as shown in Fig. 17, the first surface roughening treatment is performed by the first surface roughening liquid. The first surface roughening liquid was prepared by mixing a mixture of acetic acid and hydrochloric acid, and was roughened by etching at room temperature for 1 minute.

Next, by the photolithography method, an open pattern is formed in the range 340 (refer to FIG. 17), and the removing portion and the step forming step are performed by the ICP plasma etching method containing hydrochloric acid gas, and the etching range 340 is performed. A non-removed portion 380 is formed which exposes the current diffusion layer 307 and the outside thereof (refer to FIG. 18).

Next, as shown in Fig. 18, a second ohmic electrode 322 is formed. Next, as shown in FIG. 19, the protective laminate of an insulating film 350 composed of SiO _2, to form a protective insulating film is formed of SiO ₂ covers the surface 350 and the light emitting portion 308 of the side surface of the first semiconductor layer 303.

Next, the scribe line is scribed along the scribed range 342 (refer to FIG. 19), the crack line is extended along the scribe line, and then the element is separated by performing the cleavage, as shown in FIG. 20, to form a luminescence Component wafer 201.

After the light-emitting element wafer 201 is formed, the light-emitting element wafer 201 is transferred onto the support tape so that the surface on which the first ohmic electrode 321 is provided is the side of the tape surface, and then the surface roughening GaP is performed by the second surface roughening liquid. A second surface roughening treatment step of the side surface and the back surface of the crystal substrate 310 (refer to Fig. 20). As the second surface roughening liquid, a mixed liquid of acetic acid, hydrofluoric acid, and iodine was produced. Then, the second surface roughening treatment was performed by etching at room temperature for 1 minute.

Each of the light-emitting element wafers produced in the examples and the comparative examples was subjected to Au-Au ultrasonic mounting, and the results of comparison were shown in Fig. 21. In the comparative example, damage caused by vibration of the wafer which is considered to be the cause or vibration at the time of ultrasonic printing occurs, and the defective ratio increases. On the other hand, in the examples, the incidence of wafer breakage due to the same reason was small compared to the comparative example.

Next, the light-emitting element wafers produced in the examples and the comparative examples were each provided with an AuSn layer on the electrode and the mounting substrate, and were thermally melted (220 ° C or higher), and the results of the comparison were shown. In Figure 22. In the comparative examples and the examples, it is considered that the breakage of the heat shrinkage of AuSn after the heat fusion occurred, but as shown in Fig. 22, the breakage rate of the examples was small as compared with the comparative example.

In the embodiment, the window layer and the supporting substrate 107 are formed by epitaxial growth, and are formed in a temperature range of about 600 to 800 °C. The coefficient of linear expansion is larger than that of GaP, and AlGaInP is larger. When the temperature is lowered to room temperature after growth, due to the difference in expansion coefficient, warpage of the concave shape occurs on the substrate removal surface. Furthermore, between AlGaInP/GaP, the lattice difference is 3.7%, and this lattice difference also increases the warpage. On the other hand, due to the difference in lattice number, there is a high density difference between the window layer and the support substrate. As a result, the window layer-supporting substrate of the embodiment has a high-density through-dissipation row. Since the difference surface has the property of slipping when an external force is applied to the crystal, when the stress at the time of vibration or pressure bonding is applied to the crystal, the crystal slides along the sliding surface before the crystal is broken, thereby avoiding the mounting. As a result of the stress, it is conceivable that the wafer breakage rate is lowered.

On the other hand, in the comparative example, the same warpage as in the embodiment caused by the difference in linear expansion occurred, but the joining temperature was 350 ° C, which was lower than that in the case of the example, as compared with the case of the example. In the examples, the warpage was 1/10 or less.

Next, in the examples and the comparative examples, the step of the first ohmic electrode and the second ohmic electrode was changed to produce a light-emitting element wafer, and the bump was not provided in the manufactured light-emitting element wafer, and the flip chip was mounted. Determination of productivity. This result is shown in Figure 23. In Fig. 23, the horizontal axis represents the step difference between the first ohmic electrode and the second ohmic electrode of the embodiment and the comparative example, and the vertical axis represents the productivity of the number of wafers that can be mounted at the time of mounting.

When the flip chip is mounted, the light-emitting element wafer is pressed against the mounting surface. Due to the pressing of the light-emitting element wafer, the metal portion on the side of the mounting surface is deformed, and although the light-emitting element wafer sinks to the side of the mounting surface, the deformation is not large. Therefore, in the comparative example, as shown in FIG. 23, if the step difference between the first ohmic electrode 321 and the second ohmic electrode 322 provided on the light-emitting element wafer of the mounting surface is 3 μm or more, the first contact with the mounting surface The amount of deformation of the metal of the ohmic electrode 321 is insufficient, and although the surface of the first ohmic electrode 321 sufficiently contacts the mounting surface, the second ohmic electrode 322 may not contact the mounting surface. This result can cause a short circuit and cannot be installed. Therefore, in order to increase the amount of deformation of the electrode, in general, bumps are provided on the first ohmic electrode 321 and the second ohmic electrode 322. However, the bumps must be formed thickly by Au (gold) or the like using a gold plating method or the like, and the material cost becomes extremely high.

On the other hand, in the embodiment, the window layer-supporting substrate has a sliding surface, and as a result, the shape is variable and exerts another effect. Specifically, when the light-emitting element wafer is pressed during the flip chip mounting, the light-emitting element wafer is deformed, and the bump is not necessarily required in the flip chip mounting. That is, since the window layer and the support substrate have a sliding surface, the light-emitting element wafer is easily deformed by pressing, and the first ohmic electrode 121 is in contact with the mounting surface, and the second ohmic electrode 122 is also in contact with the mounting surface. Since both the first ohmic electrode 121 and the second ohmic electrode 122 are in contact with the mounting surface, a strong bonding can be formed between the mounting surface and the electrode by ultrasonic bonding or the like. Therefore, as shown in Fig. 23, even if the step difference between the first ohmic electrode and the second ohmic electrode of the embodiment is in the range of 3 μm or more and 11 μm or less, it is possible to perform the flip chip mounting with good productivity without using expensive bumps. .

Further, the present invention is not limited to the above embodiments. The above-described embodiments are exemplified, and those having substantially the same technical concept as those described in the claims of the present invention have the same effects, and are included in the technical scope of the present invention.

1‧‧‧Lighting element chip
11‧‧‧Lighting element chip
101‧‧‧Starting substrate
102‧‧‧Select etching layer
102A‧‧‧Second selective etching layer
102B‧‧‧First choice etching layer
103‧‧‧First semiconductor layer
103A‧‧‧Low Al composition
103B‧‧‧High Al layer
104‧‧‧Active layer
105‧‧‧Second semiconductor layer
106‧‧‧buffer layer
107‧‧‧Window layer and support substrate
108‧‧‧Lighting Department
109‧‧‧ epitaxial substrate
110‧‧‧Light-emitting element substrate
121‧‧‧First ohmic electrode
122‧‧‧Second ohmic electrode
122a‧‧‧Predetermined range
123‧‧‧Light-shielding mask
140‧‧‧Scope
141‧‧‧ Formation Department
142‧‧‧scribed range
150‧‧‧Insulation protective film
170‧‧‧Removal
180‧‧‧Non-removal department
201‧‧‧Lighting element chip
301‧‧‧Starting substrate
302‧‧‧Select etching layer
302A‧‧‧Second selective etching layer
302B‧‧‧First choice etching layer
303‧‧‧First semiconductor layer
304‧‧‧Active layer
305‧‧‧Second semiconductor layer
306‧‧‧buffer layer
307‧‧‧current diffusion layer
308‧‧‧Lighting Department
309‧‧‧ epitaxial substrate
310‧‧‧GaP single crystal substrate
311‧‧‧Light-emitting element substrate
321‧‧‧First ohmic electrode
322‧‧‧second ohmic electrode
340‧‧‧Scope
342‧‧‧scribed range
350‧‧‧Insulation protective film
380‧‧‧ Non-removal department

Fig. 1 is a step diagram showing an example of a method of mounting a light-emitting element of the present invention. Fig. 2 is a schematic view showing an epitaxial substrate in which a selective etching layer, a light-emitting portion, and a window layer-supporting substrate are grown on a starting substrate in the method of mounting a light-emitting device of the present invention. Fig. 3 is a schematic view showing a light-emitting element substrate from an epitaxial substrate removal start substrate and a second selective etching layer in the method of mounting a light-emitting element of the present invention. Fig. 4 is a schematic view showing a light-emitting element substrate on which a first ohmic electrode is formed in a method of mounting a light-emitting element of the present invention. Fig. 5 is a schematic view showing a light-emitting element substrate on which the first surface roughening treatment has been performed in the method of mounting a light-emitting element of the present invention. Fig. 6 is a schematic view showing a light-emitting element substrate in which a removal portion and a step forming step are performed in the method of mounting a light-emitting element of the present invention. Fig. 7 is a schematic view showing a light-emitting element substrate in which a second ohmic electrode is formed and an insulating protective film is formed, in a method of mounting a light-emitting element of the present invention. Fig. 8 is a schematic view showing a light-emitting element wafer produced by separating a light-emitting element of a method of mounting a light-emitting element of the present invention. Fig. 9 is a schematic view showing a light-emitting element substrate on which the first surface roughening treatment has been performed in the embodiment. Fig. 10 is a schematic view showing a light-emitting element substrate in which the removal portion and the step difference forming step of the embodiment are shown. Fig. 11 is a schematic view showing a light-emitting element substrate of the embodiment in which a second ohmic electrode is formed and an insulating protective film is formed. Fig. 12 is a schematic view showing a light-emitting element wafer produced by separating the light-emitting elements of the embodiment. Fig. 13 is a schematic view showing an epitaxial substrate in which a selective etching layer, a light-emitting portion, and a window layer-supporting substrate are grown on a starting substrate in a comparative example. Fig. 14 is a schematic view showing a substrate of a comparative example in which a GaP single crystal substrate is bonded to an epitaxial substrate. Fig. 15 is a schematic view showing a bonded substrate from the epitaxial substrate removal starting substrate and the second selective etching layer of the comparative example. Fig. 16 is a schematic view showing a bonded substrate on which a first ohmic electrode is formed in a comparative example. Fig. 17 is a schematic view showing a bonded substrate on which the first surface roughening treatment of the comparative example is performed. Fig. 18 is a schematic view showing a removed portion, a step forming step, and a bonded substrate on which a second ohmic electrode is formed in a comparative example. Fig. 19 is a schematic view showing a bonded substrate on which an insulating protective film is formed in a comparative example. Fig. 20 is a schematic view showing a light-emitting element wafer produced by separating a light-emitting element of a comparative example. Fig. 21 is a view showing the occurrence rate of failure in the case of mounting using ultrasonic waves in the examples and the comparative examples. Fig. 22 is a graph showing the occurrence rate of defects in the case of mounting using a eutectic metal layer of the examples and the comparative examples. Fig. 23 is a graph showing the relationship with the through rate when the step difference between the first ohmic electrode and the second ohmic electrode of the examples and the comparative examples was changed.

Claims (5)

A method for mounting a light-emitting element, comprising the steps of: growing a material that is lattice-matched with the starting substrate on a starting substrate, growing by epitaxial growth, sequentially forming a first semiconductor layer, an active layer, a second semiconductor layer and a buffer layer; on the buffer layer, a material for the amorphous matrix matching system of the starting substrate is formed by epitaxial growth to form a window layer and a supporting substrate; removing the starting substrate; Forming a first ohmic electrode on the first semiconductor layer; partially forming a removal portion for exposing the second semiconductor layer, the buffer layer or the window layer and supporting substrate, and providing a step; forming a second portion in the removing portion An ohmic electrode; separating a light-emitting element formed with the first and second ohmic electrodes to form a light-emitting element wafer; and mounting the light-emitting element wafer on the mounting substrate, and forming the light-emitting element wafer The side of the first and second ohmic electrodes becomes the mounting substrate side. The method of mounting a light-emitting element according to claim 1, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are AlGaInP or AlGaAs. The method of mounting a light-emitting element according to claim 1, wherein the window layer and the support substrate are GaP or GaAsP. The method of mounting a light-emitting element according to claim 2, wherein the window layer and the support substrate are GaP or GaAsP. The method of mounting a light-emitting element according to any one of claims 1 to 4, wherein a step difference between the first ohmic electrode and the second ohmic electrode is 3 μm or more and 11 μm or less.