JP2009283806A - Production process of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production process of a semiconductor device easy to handle and having little level difference, and moreover, is suited for microfabrication. <P>SOLUTION: A semiconductor layer 2 is grown on a GaAs substrate 1 and the semiconductor layer 2 is stuck to a transparent support 4 by means of a heat-resisting ultraviolet-light peeling tape 5. After a resist layer 6 is formed via the heat-resisting ultraviolet light peeling tape 5, the GaAs substrate 1 is removed (peeled off) from the semiconductor layer 2 by the wet etching method, in a state with the substrate 1 stuck to the support. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device such as an optical semiconductor device.

  In general, in an optical semiconductor device (light emitting diode LED), a semiconductor layer composed of an n layer, an active layer, a p layer, and the like is grown on a growth substrate, and an n-side electrode and a p-side electrode are formed on the growth substrate and the semiconductor layer, respectively. . In this case, when the growth substrate is insulating, a part of the growth substrate is removed by a dry etching method such as a reactive ion etching method, and an n-side electrode and a p-side electrode are formed on the n layer and the p layer of the semiconductor layer, respectively. To do.

  Recently, among the above-described optical semiconductor devices, a so-called epifilm type optical semiconductor device in which a growth substrate is removed (peeled) from a semiconductor layer has been developed (see FIG. 2E of Patent Document 1). The removal of the growth substrate improves the electrical, thermal, and optical characteristics of the epifilm type optical semiconductor device. Also, the removal of the growth substrate results in an epifilm type optical semiconductor device having a thickness of about 3 to 10 μm. Therefore, applications such as downsizing of the package of the optical semiconductor device and direct mounting of the optical semiconductor device on a circuit board are expected. (Reference: Patent Document 2).

  A first manufacturing method of a conventional epifilm type optical semiconductor device will be described with reference to FIGS. 10 and 11 (refer to FIGS. 1 and 2 of Patent Document 1).

  First, referring to FIG. 10A, an underlayer 102, an n-type contact layer 103, and an n-type cladding layer 104 are formed on a light-transmitting growth substrate 101 by metal organic compound vapor deposition (MOCVD) or the like. The active layer 105, the p-type cladding layer 106, and the p-type contact layer 107 are sequentially grown. Here, the n-type contact layer 103, the n-type cladding layer 104, the active layer 105, the p-type cladding layer 106, and the p-type contact layer 107 are referred to as a semiconductor layer (also referred to as an epitaxial film) S. The reason why the growth substrate 101 is a light-transmitting sapphire substrate, for example, is to irradiate an interface between the growth substrate 101 and the semiconductor layer S, which will be described later, from the opposite side of the semiconductor layer S.

  Next, referring to FIG. 10B, in order to separate the semiconductor layer S into optical semiconductor device (chip) units, an element isolation trench that reaches the base layer 102 by a dry etching method such as a reactive ion etching method. 108 is formed.

  Next, referring to FIG. 11A, the laser beam L is irradiated from the growth substrate 101, and the semiconductor layer S is peeled from the base layer 102 and the growth substrate 101 at the interface between the base layer 102 and the n-type contact layer 103. To do. In this case, the material of the base layer 102 and the n-type contact layer 103 is selected so that the energy gap of the n-type contact layer 103 is smaller than the energy gap of the base layer 102, and the energy of the laser light L is set to two energy gaps. Set in between. As a result, the laser light L reaches the base layer 102 and is absorbed by the n-type contact layer 103. Therefore, cavitation occurs at the interface between the base layer 102 and the n-type contact layer 103, and the growth substrate 101 is separated from the semiconductor layer S together with the base layer 102.

  Finally, referring to FIG. 11B, an n-side electrode 109 and a p-side electrode 110 are formed on the surfaces of the n-type contact layer 103 and the p-type contact layer 107 of the peeled semiconductor layer S by vapor deposition or the like. . Thereby, a plurality of epifilm type optical semiconductor devices (chips) are completed.

Further, according to the second manufacturing method of the conventional epifilm type optical semiconductor device, a release layer is formed between the growth substrate and the semiconductor layer, and then the release layer is formed by a wet etching method using a specific etchant. By removing, the semiconductor layer is separated from the growth substrate (see: Patent Documents 2 and 3). For example, the release layer is formed of AlAs, and the release layer is removed by a wet etching method using 10% hydrofluoric acid as an etchant. Further, the completed optical semiconductor devices (chips) are directly conveyed by individual supports to facilitate the handling of thin-film optical semiconductor devices (see Patent Document 3).
JP 2003-051611 A JP 2004-172351 A JP 2005-0511117 A

  However, in the first manufacturing method of the conventional epifilm type optical semiconductor device described above, the semiconductor layer S obtained after the peeling shown in FIG. 11A is very thin as 3 to 10 μm. In the process of forming the n-side electrode 109 and the p-side electrode 110, handling to transfer equipment, attachment, etc., resist coating on the semiconductor layer S when directly mounting on a circuit board, etc., resist patterning, etc. There is a problem that it is easily damaged in handling.

  Further, in the second manufacturing method of the conventional epifilm type optical semiconductor device described above, there is no unevenness on the peeling surface of the semiconductor layer for removing the peeling layer by the wet etching method, and as a result, the light extraction efficiency is lowered. There is a problem of doing. In addition, the optical semiconductor device with an individual support for facilitating handling has a substantially large thickness (≧ 3 μm). As a result, the level difference of the optical semiconductor device when directly mounted on a circuit board or the like becomes large, and there is a problem that a resist having a thickness of about 1 μm cannot be uniformly applied and subsequent fine processing is impossible.

  Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device that is easy to handle and has a small level difference and is suitable for fine processing.

  In order to solve the above-described problems, a method of manufacturing a semiconductor device according to the present invention includes a step of growing a semiconductor layer on a substrate, a step of attaching the semiconductor layer to a support via a release tape, And a step of removing the substrate from the semiconductor layer in a state of being attached to the support.

  Further, the method includes a step of forming a resist layer in a region other than the substrate and the semiconductor layer on the support and the release tape, and the substrate removal step is a step of removing the substrate by wet etching using the resist layer as a mask.

  Furthermore, the method includes forming irregularities on the surface of the semiconductor layer after removing the substrate.

  According to the present invention, handling can be facilitated.

  1 and 2 are cross-sectional views showing a first embodiment of a semiconductor device manufacturing method according to the present invention.

  First, referring to FIG. 1A, a semiconductor layer 2 is grown on a GaAs substrate 1 as a growth substrate by MOCVD or the like. For example, the semiconductor layer is an n-type contact layer, an n-type cladding layer, an active layer, a p-type cladding layer, and a p-type contact layer. Thereby, an epi wafer is obtained.

  Next, referring to FIG. 1B, the p-side electrode 3 is formed on the p-type contact layer of the semiconductor layer 2 of the epi-wafer shown in FIG. In the case of the flip chip type, the n-side electrode is also formed by etching the n-type contact layer of the semiconductor layer 2 by a dry etching method such as a reactive ion etching method.

  Next, referring to (C) of FIG. 1, the epiwafer with electrode shown in (B) of FIG. 1 is turned over, and a heat resistant ultraviolet (UV) release tape 5 (for example, Sekisui Chemical Co., Ltd.) is applied to the transparent support 4 made of sapphire or the like. Affixed through heat-resistant selffa (registered trademark) or the like. In this case, the transparent support 4 prevents the heat resistant UV peeling tape 5 from moving. When the heat-resistant UV peeling tape 5 moves, unnecessary force is applied to the semiconductor layer 2 and causes cracking.

  Next, referring to FIG. 2A, in order to form a resist layer 6 described later, the back surface (GaAs substrate 1 side) of the epi-wafer is covered with a protective sheet 1a. Next, a resist (not shown) is dropped on the protective sheet 1a, and then the transparent support 4 is rotated as indicated by an arrow, so that the resist layer 6 is formed around the epitaxial wafer as shown in FIG. To form uniformly. Then, the above-mentioned protective sheet 1a is removed.

  In this way, the resist layer 6 covers the periphery of the epi-wafer and the region where the epi-wafer of the heat-resistant UV peeling tape 5 does not exist. As a result, intrusion of the etchant from the periphery of the epi-wafer and dissolution of the surface of the heat-resistant UV peeling tape 5 in the etching process described later are prevented, and as a result, the epi-wafer is prevented from peeling from the heat-resistant UV peeling tape 5. Further, the resist layer 6 is baked at a high temperature of 140.degree. This improves the adhesion of the resist layer 6 around the epi-wafer and prevents the heat-resistant UV peeling tape 5 in the subsequent process from being peeled off by the organic solvent.

Next, referring to FIG. 2C, the GaAs substrate is removed (peeled) by a wet etching method using a NH ₄ OH + H ₂ O ₂ + H ₂ O mixed solution.

Next, referring to FIG. 3A, a resist pattern (not shown) is formed on the peeled surface of the semiconductor layer 2 to form a concavo-convex shape by a dry etching method, and the resist pattern is removed. Thereby, the light extraction efficiency is improved. Thereafter, the resist layer 6 is removed by an organic solvent or by O ₂ plasma treatment.

  Next, referring to FIG. 3B, the n-side electrode 7 is formed on the uneven surface of the semiconductor layer 2. In this case, pattern formation by a resist layer, metal vapor deposition, and resist removal are performed (not shown). In the case of the flip chip type, since the n-side electrode is already formed in the process of FIG. 1B, the process of FIG. 3B becomes unnecessary.

Next, referring to FIG. 3C, the semiconductor layer 2 is separated for each optical semiconductor device (chip). In this case, pattern formation with a resist layer, removal of the semiconductor layer 2 by wet etching or dry etching, and removal of the resist layer by O ₂ plasma treatment are performed (not shown).

  Finally, referring to FIG. 4, ultraviolet rays UV are irradiated from the back surface of the transparent support 4 to reduce the adhesive force between the heat-resistant UV peeling tape 5 and the optical semiconductor device (chip). In this state, the optical semiconductor device (chip) is picked up by the collet 8 that adsorbs the thermal peeling tape pieces. This is because chip cracking occurs in normal collet adsorption.

  As described above, since the epi-wafer is attached to the transparent support 4 via the heat-resistant UV peeling tape 5, handling in each process, for example, the removal (peeling) process of the GaAs substrate 1 is facilitated, and generation of cracks can be prevented. In addition, it is possible to form a uniform resist layer on the peeled surface of the semiconductor layer 2 after the removal (peeling) of the GaAs substrate 1, and for example, it is easy to form unevenness on the semiconductor layer 2.

  According to the formation of the resist layer 6 shown in FIG. 2B described above, the resist layer 6 may cover the interface between the GaAs substrate 1 and the semiconductor layer 2. As a result, in the step of removing (stripping) the GaAs substrate 1 shown in FIG. 2C, the removal of the GaAs substrate 1 in the vicinity of the epi-wafer periphery may be incomplete.

  5 and 6 are cross-sectional views showing a second embodiment of a method for manufacturing a semiconductor device according to the present invention.

  After the steps (A) and (B) in FIG. 1, referring to FIG. 5 (A), a heat-resistant UV peeling tape 5 'with a protective sheet 5a is stuck on the semiconductor layer 2 of the epi-wafer. This heat resistant UV peeling tape 5 'is smaller than the heat resistant UV peeling tape 5 in FIG. 2C and does not cover the periphery of the epi-wafer.

  Next, referring to FIG. 5B, a resist (not shown) is dropped on the protective sheet 5a, and then the epi-wafer is rotated as indicated by an arrow so that the resist layer 6-1 is surrounded by the periphery of the epi-wafer. And uniformly formed on the side surface of the heat-resistant UV peeling tape 5 '. Next, the protective sheet 5a is peeled off.

  Next, referring to FIG. 6A, the epi-wafer is attached to the transparent support 4 via the heat-resistant UV peeling tape 5 '.

  Next, referring to FIG. 6B, a resist layer 6-2 is applied on the transparent support 4 around the heat-resistant UV peeling tape 5 '.

  Thereafter, the process proceeds to step (C) in FIG.

  Thus, in the second embodiment of the present invention, the obtained resist layers 6-1 and 6-2 are baked. The resist layers 6-1 and 6-2 together correspond to the resist layer 6 in FIG. 2B, but unlike the resist layer 6 in FIG. 2B, the GaAs substrate 1 and the semiconductor layer. 2 is not covered reliably, the GaAs substrate 1 can be completely removed (peeled) in the step of removing (peeling) the GaAs substrate 1 shown in FIG.

  7 and 8 are cross-sectional views showing a third embodiment of a method of manufacturing a semiconductor device according to the present invention.

  After the steps of FIGS. 1A and 1B, referring to FIG. 7A, a step of about 1 μm is provided around the semiconductor layer 2 by dry etching using a SiO 2 mask.

  Next, referring to FIG. 7B, a resist layer 6-3 is formed by applying a resist spin to an adhesive portion around the semiconductor layer 2.

  On the other hand, referring to FIG. 8A, a heat-resistant UV peeling tape 5 ′ with a protective sheet 5 b smaller than the epi-wafer shape is attached to the transparent support 4.

  Next, referring to FIG. 8B, a resist (not shown) is dropped on the protective sheet 5b, and then the transparent support 4 is rotated as indicated by an arrow, thereby causing the resist layer 6-4 to rotate. Is uniformly formed around the heat resistant UV peeling tape 5 ′ and on the upper surface of the transparent support 4. Next, the protective sheet 5b is peeled off.

  Next, referring to FIG. 9, the epi-wafer shown in FIG. 7B is attached to the heat-resistant UV release layer 5 'shown in FIG.

  Thereafter, the process proceeds to step (C) in FIG.

  Thus, in the third embodiment of the present invention, the obtained resist layers 6-3 and 6-4 are baked. The resist layers 6-3 and 6-4 together correspond to the resist layer 6 of FIG. 2B, but unlike the resist layer 6 of FIG. 2B, the GaAs substrate 1 and the semiconductor layer. 2 is not covered reliably, the GaAs substrate 1 can be completely removed (peeled) in the step of removing (peeling) the GaAs substrate 1 shown in FIG. Furthermore, cracking around the epi-wafer can be prevented.

  In the above-described embodiment, a GaAs substrate is used as a growth substrate, but another substrate such as a GaN substrate may be used. Further, instead of the heat-resistant UV release tape, a heat release tape may be used. In this case, infrared light is used instead of the ultraviolet light UV in FIG.

It is sectional drawing which shows 1st Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 1st Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 1st Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 2nd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 2nd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 2nd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 3rd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 3rd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows 3rd Embodiment of the manufacturing method of the semiconductor device of this invention. It is sectional drawing which shows the 1st manufacturing method of the conventional semiconductor device. It is sectional drawing which shows the 1st manufacturing method of the conventional semiconductor device.

Explanation of symbols

1: GaAs substrate 2: Semiconductor layer 3: p-side electrode 4: transparent support 5, 5 ′: heat-resistant ultraviolet light peeling tape 5a, 5b: protective sheets 6, 6-1, 6-2, 6-3, 6 -4: Resist layer 7: n-side electrode

Claims (8)

Growing a semiconductor layer on the substrate (1);
Attaching the semiconductor layer to the support (4) via a release tape (5, 5 ');
Removing the substrate from the semiconductor layer in a state in which the semiconductor layer is attached to the support. And a step of forming a resist layer (6, 6-1, 6-2, 6-3, 6-4) in a region other than the substrate and the semiconductor layer on the support and the release tape,
The substrate removing step is a step of removing the substrate by wet etching using the resist layer as a mask.
A method for manufacturing a semiconductor device according to claim 1. The resist layer forming step includes
Attaching a protective sheet (1a) to the opposite side of the release tape of the substrate;
Forming the resist layer by dropping the resist on the protective sheet and rotating the support;
The method for manufacturing a semiconductor device according to claim 2, further comprising: removing the protective sheet after forming the resist layer. The resist layer forming step includes
Attaching the release tape with the protective sheet (5a) to the semiconductor layer;
Forming a first resist layer (6-1) by dropping a resist on the protective sheet and rotating the substrate;
Removing the protective sheet after forming the first resist layer;
And a step of forming a second resist layer (6-2) on the support after the semiconductor layer is attached to the support through the release tape, and the first and second resists. A method of manufacturing a semiconductor device in which the resist layer is formed of layers. The resist layer forming step includes
Etching away the periphery of the semiconductor layer;
Forming a first resist layer (6-3) around the semiconductor layer removed by etching;
Attaching a protective sheet (5b) to the opposite surface of the support of the release tape excluding the periphery of the release tape;
Forming a second resist layer (6-4) on the support and the periphery and side surfaces of the release tape by dropping a resist on the protective sheet after the release tape is attached to the support;
And a step of removing the protective sheet after forming the second resist layer, and manufacturing the semiconductor device in which the resist layer is configured by the first and second resist layers.   The method for manufacturing a semiconductor device according to claim 1, further comprising forming irregularities on a surface of the semiconductor layer after removing the substrate.   The method of manufacturing a semiconductor device according to claim 1, wherein the release tape is a heat-resistant ultraviolet light release tape. The method of manufacturing a semiconductor device according to claim 1, wherein the release tape is a thermal release tape.

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