JP4799041B2 - Nitride semiconductor device manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a nitride compound-based semiconductor device.

  In recent years, nitride-based semiconductor elements such as GaN, InN, and AlN have been actively used as materials for electronic devices such as light emitting elements such as blue and green light emitting diodes (LEDs) and blue-violet semiconductor lasers, and high-speed transistors that can operate at high temperatures. It has been. Since this nitride-based semiconductor element is generally difficult to manufacture a bulk single crystal, it is formed on a heterogeneous substrate (growth substrate) such as sapphire or SiC by using a hetero-epitaxial growth method (for example, (See Patent Document 1 and Patent Document 2.)

  Specifically, the nitride-based semiconductor element is manufactured by the following process.

  First, a nitride semiconductor element layer made of GaN or the like is sequentially epitaxially grown on a growth substrate, and then an electrode is formed by a vacuum deposition method. On the other hand, a support substrate on which a solder layer made of Au—Sn alloy, eutectic solder or the like is formed is prepared, and the nitride-based semiconductor element layer and the support substrate are bonded via the solder layer. Next, the growth substrate is removed from the support substrate and the nitride-based semiconductor element layer by, for example, melting the semiconductor element layer near the nitride-based semiconductor element layer interface.

In this way, as shown in FIG. 9, the p-side electrode 4 and the p-side pad electrode 5 are formed on the n-side GaN layer 2 and the p-side GaN layer 3, and the n-side GaN layer 2 has the n-side A nitride-based semiconductor element in which the pad electrode 9 is formed and bonded to the support substrate 6 through the solder layer 7 is obtained.
Japanese Patent Laid-Open No. 11-30780 JP 2000-277804 A

  When the support substrate is bonded and the growth substrate is separated and removed as described above, the mesa etch depth (for example, 1 to 3 μm) of the p-side GaN layer 3 and the p-side pad electrode 5 as shown in FIG. Due to the thickness (for example, 1 to 3 μm), the cavity 11 is generated between the nitride-based semiconductor layer and the solder layer 7. A plurality of light emitting elements composed of nitride-based semiconductor element layers are formed on the support substrate 6, and the cavities 11 are scribed when dividing each of the plurality of light emitting elements (P portion in FIG. 9). It will be hit. Usually, the nitride-based semiconductor element layers (n-side GaN layer 2 and p-side GaN layer 3 in FIG. 9) forming the light-emitting element are as thin as about 0.3 to 10 μm. In some cases, the nitride-based semiconductor element layer is bent by the pressure and cracks are generated from the scribe line toward the light emitting region, thereby reducing the yield.

The present invention has been made in view of the above problems, when dividing into each of a plurality of light emitting elements, cracks without entering to the light emitting region, to provide a method for manufacturing a nitride compound-based semiconductor device that to suppress the reduction in yield With the goal.

In order to achieve the above object, a first feature of the present invention is that a plurality of light-emitting elements comprising at least one nitride-based semiconductor element layer are formed on a growth substrate, and a nitride-based semiconductor element layer is formed. and bonding a supporting substrate, a manufacturing method for a nitride semiconductor device and a step of removing the growth substrate from the bonded nitride-based semiconductor element layer and the support substrate, the divided regions of the plurality of light emitting elements corresponding to the cavity between the supporting substrate a nitride-based semiconductor element layer, and summarized in that a method of manufacturing a nitride-based semiconductor device having a step of filling the resin.

According to the method for manufacturing a nitride-based semiconductor device according to the first feature, since the hollow portion serving as the scribe position is filled with the resin, no cracks are formed in the light emitting region when dividing each light emitting device. , Yield reduction can be suppressed.

In the method for manufacturing a nitride semiconductor device according to the first feature, the resin is preferably a thermosetting resin. Further, the viscosity of the resin, preferably not more than 100cp at 25 ° C..

According to the present invention, when dividing into each of a plurality of light emitting elements, cracks without entering to the light emitting region, it is possible to provide a manufacturing method of the nitride compound-based semiconductor device that to suppress the decrease in yield.

Next, with reference to the accompanying drawings, illustrating the implementation of the embodiment of the present invention. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(First embodiment)
In the first embodiment, a step of forming a plurality of light-emitting elements composed of at least one nitride-based semiconductor element layer on a growth substrate, and a step of bonding a support substrate on the nitride-based semiconductor element layer And a step of removing the growth substrate from the bonded nitride-based semiconductor element layer and the support substrate, and in a cavity between the nitride-based semiconductor element layer and the support substrate, which is a divided region of the plurality of light-emitting elements, A nitride semiconductor device filled with resin will be described.

  In the nitride-based semiconductor device according to the first embodiment, as shown in FIG. 1, a p-side electrode 4 and a p-side pad electrode 5 are formed on an n-side GaN layer 2 and a p-side GaN layer 3, An n-side pad electrode 9 is formed on the n-side GaN layer 2 and is joined to the support substrate 6 via the solder layer 7.

  Further, a thermosetting resin such as an epoxy resin is formed in a cavity between the nitride semiconductor element layer (n-side GaN layer 2) corresponding to the divided region (P portion in FIG. 1) of the plurality of light emitting elements and the support substrate 6. 10 is filled. The thermosetting resin may have any workability and an insulating property. Therefore, the viscosity at 25 ° C. is preferably 100 cp (centi-poise) or less. In order to maintain strength, the Shore hardness is preferably 75 or more. As such a thermosetting resin, for example, ME-514 / HV-514 or ME-550 / HV-550 manufactured by Nippon Pernox may be used.

  The nitride semiconductor device according to the first embodiment is divided into a plurality of light emitting devices by a diamond point 14 or a dicing saw in a region filled with the resin 10 as shown in FIG. The

  Next, a method for manufacturing the nitride semiconductor device according to the first embodiment will be described with reference to FIG.

First, as shown in FIG. 3A, an n-side GaN layer 2 and a p-side GaN layer 3 are formed on a sapphire substrate (growth substrate) 13 by MOCVD (Metal Organic Chemical Vapor Deposition). Specifically, a buffer layer, an n-type contact layer, an n-type cladding layer, a photoactive layer, a p-type cap layer, a p-type cladding layer, and a p-type contact layer are sequentially grown. Next, a groove is formed by mesa etching in a lattice shape up to the n-type cladding layer by photolithography, and the p-type contact layer to the photoactive layer are separated for each light emitting element. Next, the p-side electrode 4 is formed, the insulating film 8 made of SiO ₂ having a contact hole is formed at the place where the p-side pad electrode 5 is to be formed, and the p-side pad electrode 5 whose surface is made of Au is formed. .

  On the other hand, as the support substrate 6, a sintered body substrate of copper and copper oxide particles, which is a material having a thermal expansion coefficient smaller than that of pure copper and having low heat conduction and electrical resistance, is prepared. The support substrate 6 is not limited to this material, and a metal and an alloy such as tungsten, or a semiconductor substrate such as a cleaved Si, SiC, or GaAs substrate can be used. It is preferable to prepare a support substrate 6 that is about 1 to 5 mm larger than the end face of the growth substrate 13 for a subsequent resin filling step. Then, a solder layer 7 made of Au—Sn alloy, eutectic solder or the like is formed on the support substrate 6.

  Next, as shown in FIG. 3B, the nitride-based semiconductor element layer surface of the growth substrate 13 on which the plurality of light emitting elements are formed and the solder layer 7 of the support substrate 6 are joined by thermocompression bonding.

  Next, as shown in FIG. 3C, the substrate is separated between the growth substrate 13 and the nitride-based semiconductor element layer, and the nitride-based semiconductor element layer (the n-side GaN layer 2 and the p-side GaN layer 3) is supported. A laminated substrate is obtained in which the substrate 6 is bonded with the solder layer 7. For substrate separation, polishing, dry etching, wet etching, a laser lift-off method, or the like is used according to the material of the growth substrate 13.

  Next, a thermosetting resin such as an epoxy resin is made to enter the cavity 11 generated in a lattice shape at the bonding interface by utilizing a capillary phenomenon. When the support substrate 6 having a slightly larger area than the growth substrate 13 is used, a thermosetting resin is disposed on the end surface of the support substrate 6 protruding from the nitride-based semiconductor element layer, thereby thermosetting the cavity 11. A functional resin can be made to enter.

  In this way, the nitride semiconductor device shown in FIG. 1 can be obtained.

  According to the nitride-based semiconductor device according to the first embodiment, when the cavity portion 11 is filled with resin, when divided into a plurality of light emitting devices by the diamond point 14 or the dicing saw, due to the mechanical pressure. Since the nitride-based semiconductor element layer that forms the light-emitting element does not bend, cracks that occur from the scribe line toward the light-emitting region can be prevented. As a result, it is possible to suppress a decrease in yield in scribing. The present invention is particularly effective when the nitride-based semiconductor element layer is as thin as about 1 to 50 μm.

  Further, since the thin film nitride-based semiconductor element layer (n-side GaN layer 2 in FIG. 1) having a thickness of several μm is fixed without being floated, the nitride-based semiconductor element layer is missing when the light-emitting element is handled. Can be prevented.

  Further, since the cavity 10 is filled with the resin 10, as shown in FIG. 4, the nitride-based semiconductor element layer is not broken by the pressurization at the time of wire bonding with the Au wire 15 or the like, and the n-side pad electrode 9 is not broken. Can be provided at the end of the light emitting element. Thus, when the n-side pad electrode 9 is provided at the end of the light emitting element, the ratio of light emission from the surface is reduced, and the light extraction efficiency is improved.

(Second reference form)
In the second reference embodiment, a step of forming a plurality of light-emitting elements composed of at least one nitride-based semiconductor element layer on a growth substrate, and a step of bonding a support substrate on the nitride-based semiconductor element layer, And a step of removing the growth substrate from the bonded nitride-based semiconductor element layer and the support substrate, and in a cavity between the nitride-based semiconductor element layer and the support substrate, which is a divided region of the plurality of light-emitting elements, A nitride semiconductor device in which an abnormally grown nitride semiconductor device layer is disposed will be described.

As shown in FIG. 5, the nitride-based semiconductor device according to the second reference form has a p-side electrode 4 and a p-side pad electrode 5 formed on an n-side GaN layer 2 and a p-side GaN layer 3. An n-side pad electrode 9 is formed on the n-side GaN layer 2 and is joined to the support substrate 6 via the solder layer 7.

  In addition, the cavity between the nitride-based semiconductor element layer (n-side GaN layer 2) and the support substrate 6 corresponding to the divided region (P portion in FIG. 5) of the plurality of light-emitting elements is thicker than the n-side GaN layer 2. A nitride-based semiconductor element layer 12 (hereinafter referred to as “abnormally grown epitaxial layer”) that has been formed into a film and abnormally grown is disposed. Details of the abnormally grown epitaxial layer 12 will be described later.

Then, as shown in FIG. 6, the nitride-based semiconductor device according to the second reference embodiment is a region where the abnormally grown epitaxial layer 12 is disposed, and each of the plurality of light emitting devices is formed by a diamond point 14 or a dicing saw. It is divided into.

Next, a manufacturing method for a nitride semiconductor device according to the second reference embodiment will be described with reference to FIGS. FIG. 7 is a plan view in which two light emitting elements are arranged, and FIG. 8 is an enlarged cross-sectional view in the vicinity of the abnormally grown epitaxial layer 12.

First, as shown in FIGS. 7 and 8A, a substrate separating thin film 19 made of TiO ₂ is formed on a GaN substrate (growth substrate) 13. The substrate separating thin film 19 may use Al ₂ O ₃ , SiO ₂ , Si ₃ N ₄ , Ta ₂ O ₅ , W, Ti, Pt, Mo, or the like in addition to TiO ₂ . The substrate separating thin film 19 functions as an isolation region for separating the growth substrate 13 and the nitride-based semiconductor element layer. For example, when the growth substrate 13 is separated by laser irradiation, the substrate separating thin film 19 becomes a region that is instantaneously dissolved by the energy of the laser.

When such a substrate separating thin film 19 is formed on a GaN substrate (growth substrate) 13 and a GaN layer or an InGaN layer is epitaxially grown thereon, it is close to the end of the surface on which the substrate separating thin film 19 is formed. The growth rate at the exposed portion of the GaN substrate (growth substrate) becomes abnormally large. This is because the radical species generated by heating the source gas are more likely to adhere on GaN than on TiO ₂ , so that radical species on the TiO ₂ pattern are excessively supplied at the end of the substrate separation thin film 19 due to the microphone. This is because the growth rate increases. This phenomenon is called a so-called masking effect.

  Although the width of abnormal growth depends on conditions, it is generally observed that abnormal growth occurs from the end of the substrate separating thin film 19 to a distance of about 10 μm. In addition, the growth rate of the abnormally grown epitaxial layer 12 may be twice or more that of normal epitaxial growth.

  If the thickness of the substrate separating thin film 19 reflects the GaN crystal structure of the growth substrate 13, the thickness of the substrate separating thin film 19 can be epitaxially grown on the substrate separating thin film 19. Is preferred. Further, since there is an abnormal growth of about 10 μm from the end portion of the substrate separating thin film 19, it is preferable to set the distance L4 between the substrate separating thin films 19 to about 20 μm. By setting the thickness to about 20 μm, an abnormally grown layer can be formed over the interval L4 of the substrate separating thin film 19. In FIG. 7, the thin film 19 for substrate separation is 330 × 330 μm square.

  Next, the n-side GaN layer 2 and the p-side GaN layer 3 are formed on the GaN substrate (growth substrate) 13 and the substrate separating thin film 19 by MOCVD. Specifically, a buffer layer, an n-type contact layer, an n-type cladding layer, a photoactive layer, a p-type cap layer, a p-type cladding layer, and a p-type contact layer are sequentially grown. In FIG. 8A, the thickness A4 of the substrate separating thin film 19 is 3 nm, the thickness A3 of the n-side GaN layer 2 is 1 μm, the thickness A2 of the p-side GaN layer 3 is 1 μm, and the abnormally grown epitaxial layer 12 The thickness A4 is about 2 μm. Thus, the thickness A1 of the abnormally grown epitaxial layer 12 is twice the thicknesses A2 and A3 of the n-side GaN layer 2 or the p-side GaN layer 3 that normally grows.

  Next, as shown in FIG. 8B, by mesa etching to the n-type cladding layer in a lattice shape by photolithography technology, grooves 18 are formed and separated from the p-type contact layer to the photoactive layer for each light emitting element. To do. At this time, the abnormally grown epitaxial layer 12 is left as it is without being mesa-etched. By making the depth of the mesa etching to be equal to or greater than the thickness of the p-side GaN layer 3, it is electrically separated from the adjacent light emitting element. Next, the p-side electrode 4 (thickness B1: 0.4 μm) is formed. At this time, as shown in FIG. 7, the width L3 of the region subjected to mesa etching with respect to one light emitting element is about 270 μm, and the interval L5 between the regions subjected to mesa etching is about 80 μm.

Next, as shown in FIG. 8C, an insulating film 8 made of SiO _{2 with} a contact hole opened is formed at a location where the p-side pad electrode 5 is formed, and the p-side pad electrode 5 whose surface is made of Au. (Thickness C1: 1.6 μm) is formed.

  Subsequent steps are the same as those of the nitride semiconductor device according to the first embodiment.

  That is, as the support substrate 6, a sintered body substrate of copper and copper oxide particles, which is a material having a smaller coefficient of thermal expansion than pure copper and a small thermal conductivity and electrical resistance, is prepared. Then, a solder layer 7 made of Au—Sn alloy, eutectic solder or the like is formed on the support substrate 6.

  Next, the nitride-based semiconductor element layer surface of the growth substrate 13 on which the plurality of light emitting elements are formed and the solder layer 7 of the support substrate 6 are joined by thermocompression bonding.

  Next, the substrate is separated between the growth substrate 13 and the nitride-based semiconductor element layer, and the nitride-based semiconductor element layers (n-side GaN layer 2 and p-side GaN layer 3) and the support substrate 6 are bonded by the solder layer 7. A laminated substrate is obtained. For substrate separation, polishing, dry etching, wet etching, a laser lift-off method, or the like is used according to the material of the growth substrate 13.

  In this manner, the nitride semiconductor device shown in FIG. 5 can be obtained.

According to the nitride-based semiconductor device according to the second reference embodiment, when the abnormally grown epitaxial layer 12 is disposed in the cavity portion 11, when divided into a plurality of light emitting devices by the diamond point 14 or the dicing saw, Since the epitaxial layer forming the light emitting element is not bent by the mechanical pressure, it is possible to prevent cracks generated from the scribe line toward the light emitting region. As a result, it is possible to suppress a decrease in yield in scribing.

In the second reference embodiment, the abnormally grown epitaxial layer 12 can be formed at a position higher than the surface of the p-side pad electrode 5 by adjusting the height of the abnormally grown epitaxial layer 12. In this case, the pressure on the p-side pad electrode 5 can be reduced at the time of bonding to the support substrate 6.

(Other embodiments)
Although the present invention has been described according to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

For example, in the above embodiment, the light emitting diode and the semiconductor laser that mainly use light emitted from the active layer of the nitride semiconductor element layer are exemplified. However, the present invention is not limited to this, and the light emitting diodes and the semiconductor lasers are not limited thereto. The present invention can also be used in the manufacture of a light emitting device that combines a phosphor that uses emitted light as excitation light. Further, it can be applied to electronic devices such as HEMT (High Electron Mobility Transistor) having a nitride-based semiconductor element layer, SAW (Surface Acoustic Wave) devices, and light receiving elements.

In the above embodiment, the nitride semiconductor layers are crystal-grown using the MOCVD method. However, the present invention is not limited to this, and the nitride semiconductor using the HVPE method, the gas source MBE method, or the like. Each layer may be crystal-grown.

In the above embodiment, the nitride-based semiconductor element layer including a layer made of GaN, AlGaN, InGaN, and AlN is used. However, the present invention is not limited to this, and is made of GaN, AlGaN, InGaN, and AlN. A nitride-based semiconductor element layer including layers other than the layers may be used. The semiconductor element layer may have a current confinement structure such as a mesa structure or a ridge structure.

In the above embodiment, the sapphire substrate and the GaN substrate are used as the growth substrate for the nitride-based semiconductor element layer. However, the present invention is not limited to this, and a substrate on which a nitride-based semiconductor can be grown. For example, Si, SiC, GaAs, MgO, ZnO, spinel, etc. can be used.

  The support substrate material is preferably conductive. In addition to the metal-metal oxide composite material used in the first and second embodiments, a conductive semiconductor (Si, SiC, GaAs, ZnO) is used. Etc.), metal or composite metal (Al, Fe-Ni, Cu-W, CU-Mo, etc.) can be used. In general, a metal-based material is superior to a semiconductor material in terms of mechanical characteristics and is not easily cracked, so that it is suitable as a support substrate material.

  As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is a cross-sectional view of a nitride-based semiconductor device according to a first embodiment. In FIG. 1, it is sectional drawing at the time of isolate | separating between some light emitting elements. It is sectional drawing for demonstrating the manufacturing method of the nitride type semiconductor element which concerns on 1st Embodiment. It is sectional drawing at the time of performing wire bonding after the element isolation | separation of the nitride type semiconductor element which concerns on 1st Embodiment. It is sectional drawing of the nitride-type semiconductor element which concerns on a 2nd reference form. In FIG. 5, it is sectional drawing at the time of isolate | separating between some light emitting elements. It is a top view of the nitride-type semiconductor element which concerns on a 2nd reference form. It is sectional drawing for demonstrating the manufacturing method of the nitride type semiconductor element which concerns on a 2nd reference form. It is sectional drawing of the conventional nitride semiconductor device.

2 ... n-side GaN layer 3 ... p-side GaN layer 4 ... p-side electrode 5 ... p-side pad electrode 6 ... support substrate 7 ... solder layer 8 ... insulating film 9 ... n-side pad electrode 10 ... resin 11 ... cavity 13 ... Abnormally grown epitaxial layer 14 ... Diamond point

Claims (4)

Forming a plurality of light emitting elements comprising at least one nitride-based semiconductor element layer on a growth substrate, bonding a support substrate on the nitride-based semiconductor element layer via a solder layer, and bonding And a step of removing the growth substrate from the nitride-based semiconductor device layer and the support substrate, comprising:
Filling a cavity between the nitride-based semiconductor element layer and the solder layer, which is a divided region of the plurality of light-emitting elements, with a resin ;
After the step of filling the resin, in the region filled with the resin, the nitride-based semiconductor element layer and the support substrate are divided into the plurality of light emitting elements together with the solder layer and the resin layer. And a method of manufacturing a nitride-based semiconductor device.   The method for manufacturing a nitride semiconductor device according to claim 1, wherein the resin is a thermosetting resin.   The method for manufacturing a nitride-based semiconductor element according to claim 1 or 2, wherein the viscosity of the resin is 100 cp or less at 25 ° C. After the step of filling the resin, the nitride-based semiconductor device according to any one of claims 1 to 3, wherein the resin is characterized by having a step of providing a pad electrode on a region is filled Production method.

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