Temporary bonding wafers and their manufacturing methods

Abstract

This invention relates to a temporary bonding wafer, characterized in that: it is formed by temporarily bonding an epitaxial functional layer to a support substrate; one side of the epitaxial functional layer has two or more electrodes with different polarities; and the temporary bonding wafer is formed by temporarily bonding the side of the epitaxial functional layer with the aforementioned electrodes to the aforementioned support substrate using an uncured thermosetting bonding material. This provides a technique that, in the temporary bonding wafer, reduces bonding defects and peeling defects after the substrate removal step following the bonding process, thereby improving yield, and also simplifies the removal of the temporary support substrate.

Description

Technical Field

[0001] The present invention relates to a temporary bonding method and a temporary bonding wafer, the temporary bonding method being used to temporarily bond a semiconductor substrate mounted on a mounting substrate to a temporary support substrate. Prior Technology

[0002] The technique of separating and transferring only the epitaxial functional layer, such as a light-emitting element, from the starting substrate to another substrate is important for relaxing the limitations imposed by the physical properties of the starting substrate and increasing the design freedom of the device system. To achieve this transfer, a technique is needed that, after bonding the epitaxial functional layer to a temporary support substrate, removes the starting substrate and transfers it to a permanent substrate.

[0003] Patent Document 1 discloses the following techniques: a technique for thermally bonding a semiconductor epitaxial substrate and a temporary support substrate via a dielectric layer; and a technique for separating the temporary support substrate and the epitaxial functional layer by wet etching. Although Patent Document 2 is not directly related to the improvement of bonding, as a form of bonding, it discloses a technique in which a transparent conductive layer is inserted between the adhesive layer and the functional layer.

[0004] Patent document 3 discloses a technique that uses polyimide for temporary bonding and forms an electrode on the substrate removal surface after removing the starting substrate. [Previous Technical Documents] (Patent Documents)

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-27301 Patent Document 2: Japanese Patent No. 4159421 Patent Document 3: Japanese Patent Application Publication No. 2008-187160 Summary of the Invention

[0006] [The problem the invention aims to solve] However, Patent Document 3 has the following problem: after the electrodes are formed following the temporary bonding and removal of the initial substrate, peeling can occur due to the heat treatment during the formation of the ohmic contact. In particular, when forming a heterostructure that combines a material system with a large lattice mismatch and a material with a large difference in the coefficient of thermal expansion, the peeling rate tends to increase further due to the bimetallic effect during heat treatment.

[0007] To lower the temperature required for ohmic contact formation, dopant must be applied up to concentrations close to the solid solution limit. However, the quality of a crystal layer that has been doped to near the solid solution limit is more prone to degradation than a less doped layer. The heavily doped layer must be positioned between the starter substrate and the functional layer. Since the functional layer is positioned above the heavily doped layer, it is affected by the quality of the heavily doped layer. In other words, if the quality of the heavily doped layer below the functional layer is low, the quality of the functional layer will also be reduced.

[0008] Furthermore, to avoid the effects of thermal deformation caused by bimetals, one approach is to choose materials with a small difference in their coefficients of thermal expansion. However, it is impossible to maintain the functionality of the functional layers while simultaneously choosing materials with a small difference in their coefficients of thermal expansion. Technically, the only option is to reduce the impact of the difference in coefficients of thermal expansion, i.e., to thin the film thickness of each layer. Although it is technically possible to design the film thickness to be thinner, this increases the likelihood that the carrier behavior within the functional layers cannot be adequately controlled, thus reducing the designed functionality of the functional layers.

[0009] Due to the aforementioned background, when electrodes are formed and ohmic contacts are formed after temporary bonding on the support substrate, it is extremely difficult to suppress peeling caused by the bimetallic effect.

[0010] The present invention was made in view of the problems to be solved above, and aims to provide a technology that reduces bonding defects and peeling defects after the initial substrate removal step in the temporary bonding wafer, thereby improving the yield and making the removal of the temporary support substrate easier. [Technical means to solve the problem]

[0011] To address the aforementioned problems, this invention provides a temporarily bonded wafer, which is formed by temporarily bonding an epitaxial functional layer to a supporting substrate. Each side of the epitaxial functional layer has two or more electrodes with different polarities. The temporary bonding wafer is formed by temporarily bonding the surface of the aforementioned epitaxial functional layer with the aforementioned electrode to the aforementioned support substrate using an uncured thermosetting bonding material.

[0012] If it is a temporary bonding wafer, it is formed by temporarily bonding the support substrate to the surface where the electrode is formed in an uncured state using a thermosetting bonding material. There is no bonding defect or peeling defect in the temporary bonding part, and the bonding material is bonded in an uncured state, so the temporary support substrate can be easily removed.

[0013] Furthermore, it is preferable that the aforementioned epitaxial functional layer is a light-emitting element.

[0014] The temporary bonding wafer of the present invention can be configured for such purposes.

[0015] Furthermore, it is preferable that the aforementioned epitaxial functional layer comprises AlGaInP or InGaN materials.

[0016] This invention is particularly suitable for use when it is an epitaxial functional layer containing such a material.

[0017] Furthermore, it is preferable that the aforementioned thermosetting bonding material is any one of benzocyclobutene (BCB) resin, polyimide (PI) resin, fluororesin, and epoxy resin.

[0018] If it is a thermosetting bonding material, it can not only temporarily bond in a softened state, but also be easily peeled off.

[0019] Furthermore, it is preferable that the aforementioned support substrate is made of any one of the following materials: silicon, sapphire, GaP, GaAs, InP, SiC, quartz, glass, LiTaO3, and LiNbO3.

[0020] In this invention, a support substrate such as the one described above can be used.

[0021] Furthermore, the temporary bonding wafer of the present invention can be configured such that the side of the aforementioned epitaxial functional layer opposite to the side having the aforementioned electrode does not have a starting substrate.

[0022] Such a temporary bonding wafer of the present invention can be configured to have the starting substrate removed.

[0023] Furthermore, this invention provides a method for manufacturing a temporarily bonded wafer, characterized in that: it is a method for temporarily bonding an epitaxial substrate to a support substrate, wherein the epitaxial substrate is formed by growing an epitaxial functional layer on a starting substrate, and includes: (1) The step of forming two or more electrodes of different polarities on one side of the aforementioned epitaxial functional layer of the aforementioned epitaxial substrate; and (2) The step of temporarily bonding the aforementioned support substrate to the surface on which the aforementioned electrodes are formed by means of an uncured thermosetting bonding material.

[0024] Since the temporary bonding wafer is manufactured in the manner described above, and the temporary bonding step is performed after the electrode formation step, it is not subject to the thermal limitations that occur during electrode formation. Therefore, it is possible to prevent poor bonding and delamination between the epitaxial functional layer and the temporary support substrate, thereby improving the yield. In addition, since the bonding material is temporarily bonded to the temporary support substrate in an uncured state, the temporary support substrate can be easily removed.

[0025] Furthermore, it is preferable to configure the aforementioned epitaxial functional layer as a light-emitting element.

[0026] This invention can be used to manufacture temporary bonding wafers for such applications.

[0027] Furthermore, it is preferable to set the aforementioned epitaxial functional layer to contain AlGaInP or InGaN materials.

[0028] This invention is particularly suitable for use when it is an epitaxial functional layer containing such a material.

[0029] Furthermore, it is preferable to use the aforementioned thermosetting bonding material as any one of benzocyclobutene (BCB) resin, polyimide (PI) resin, fluororesin, and epoxy resin.

[0030] If it is a thermosetting bonding material, it can not only temporarily bond in a softened state, but also be easily peeled off.

[0031] Furthermore, it is preferable that the aforementioned support substrate is made of any one of the following materials: silicon, sapphire, GaP, GaAs, InP, SiC, quartz, glass, LiTaO3, and LiNbO3.

[0032] The present invention can use, for example, a support substrate.

[0033] Furthermore, the method for manufacturing a temporary bonded wafer of the present invention may further include, after the aforementioned step (2), a step of removing the aforementioned starting substrate from the aforementioned epitaxial substrate.

[0034] If this is done, it is possible to create a temporary bonding wafer that does not have a starting substrate. [effect]

[0035] As described above, the present invention provides a technique that reduces bonding defects and peeling defects after the initial substrate removal step in the temporary bonding wafer process, thereby improving yield and making the removal of the temporary support substrate easier. Simple Explanation of the Diagram

[0036] Figure 1 is a schematic diagram showing an example of a temporarily bonded wafer according to the present invention. Figure 2 is a schematic diagram of an epitaxial substrate being fabricated by growing an epitaxial functional layer on a GaAs starter substrate in a first embodiment of the manufacturing method of the temporary bonding wafer of the present invention. Figure 3 is a schematic diagram of the formation of the first electrode on the GaP window layer in the first embodiment. Figure 4 is a schematic diagram of the AlGaInP first coating layer being exposed by dry etching in the first embodiment. Figure 5 is a schematic diagram of the formation of a second electrode on the first AlGaInP coating layer in the first embodiment. Figure 6 is a schematic diagram of a temporary bonding wafer fabricated by temporarily bonding the electrode-bearing surface of the epitaxial functional layer to a support substrate using BCB resin in the first embodiment. Figure 7 is a schematic diagram of the removal of the GaAs starter substrate from the fabricated temporary bonding wafer in the first embodiment. Figure 8 is a schematic diagram of the process in the first embodiment where a temporary bonding wafer after the removal of the GaAs starter substrate is bonded to a silicon wafer via silicon oxide and the support substrate is further peeled off. Figure 9 is a schematic diagram of an epitaxial substrate being fabricated by growing an epitaxial functional layer on a sapphire starting substrate in a second embodiment of the method for manufacturing a temporary bonded wafer according to the present invention. Figure 10 is a schematic diagram of the formation of the first electrode on the GaN contact layer in the second embodiment. Figure 11 is a schematic diagram of the GaN first cladding layer being exposed by dry etching in the second embodiment. Figure 12 is a schematic diagram of the second electrode formed on the first GaN cladding layer in the second embodiment. Figure 13 is a schematic diagram of a temporary bonding wafer fabricated by temporarily bonding the electrode-bearing surface of the epitaxial functional layer to a support substrate using BCB resin in the second embodiment. Figure 14 is a schematic diagram of the removal of the sapphire starting substrate from the fabricated temporary bonding wafer in the second embodiment. Figure 15 is a schematic diagram of the second embodiment in which the temporary bonding wafer after the sapphire starting substrate has been removed is bonded to the silicon wafer via silicon oxide and the support substrate is further peeled off. Implementation

[0037] As mentioned above, there is a problem: after the electrodes are formed by temporarily bonding the support substrate, peeling can occur due to the heat treatment during the formation of the ohmic contact. In particular, when forming a heterostructure that combines a material system with a large lattice mismatch and a material with a large difference in the coefficient of thermal expansion, the peeling rate tends to increase further due to the bimetallic effect during heat treatment.

[0038] After repeated research into the problems to be solved, the inventors discovered the following facts and thus completed the present invention: by using a thermosetting bonding material, the surfaces of two or more electrodes with different polarities of the epitaxial functional layer are temporarily bonded to the support substrate in an uncured state, without peeling of the temporary bonded portion caused by the heat treatment of the electrodes, and since the bonding is performed in an uncured state by the thermosetting bonding material, the temporary bonded support substrate can be removed very easily.

[0039] In other words, the present invention is a temporary bonding wafer, which is formed by temporarily bonding an epitaxial functional layer and a support substrate. One side of the epitaxial functional layer has two or more electrodes with different polarities. Furthermore, the temporary bonding wafer is formed by temporarily bonding the side of the epitaxial functional layer with the aforementioned electrodes to the aforementioned support substrate using an uncured thermosetting bonding material.

[0040] The present invention will be described in detail below, but the present invention is not limited thereto.

[0041] [Temporarily bonded wafers] Figure 1 shows an example of a temporary bonding wafer of the present invention. In the temporary bonding wafer 100 of the present invention, one side of the epitaxial functional layer 1 has two electrodes 2 with different polarities, and the side of the epitaxial functional layer 1 with the electrodes 2 is temporarily bonded to the support substrate 3 by an uncured thermosetting bonding material 4.

[0042] The structure of a priori temporary bond wafer is as follows: an electrode is formed on one side of the epitaxial functional layer, and a support substrate is temporarily bonded to the other side of the epitaxial functional layer (the side opposite to the electrode formation side). This is because, in the manufacturing steps of a priori temporary bond wafer, the epitaxial functional layer of the epitaxial substrate is first temporarily bonded to the support substrate, then the starting substrate is removed, and an electrode is formed on the surface after the starting substrate is removed. The epitaxial substrate is formed on the starting substrate where the epitaxial functional layer is formed. In contrast, the temporary bond wafer of the present invention differs from the priori temporary bond wafer in that an electrode is disposed between the epitaxial functional layer and the support substrate. This structure is achieved by using the manufacturing method of the temporary bond wafer of the present invention, as described below, to temporarily bond the wafer after the electrode is formed.

[0043] [Method for manufacturing temporarily bonded wafers] Therefore, the present invention provides a method for manufacturing a temporarily bonded wafer, which is a method for temporarily bonding an epitaxial substrate to a support substrate. The epitaxial substrate is formed by growing an epitaxial functional layer on a starting substrate, and includes: (1) The step of forming two or more electrodes of different polarities on one side of the aforementioned epitaxial functional layer of the aforementioned epitaxial substrate; and (2) The step of temporarily bonding the aforementioned support substrate to the surface on which the aforementioned electrodes are formed by means of an uncured thermosetting bonding material.

[0044] This method for manufacturing temporarily bonded wafers differs from previous methods that involve heat treatment (ohmic heat treatment) to form ohmic contacts for electrodes on wafers with temporary bond portions. Instead, electrode formation and ohmic heat treatment are performed on the wafer before the formation of the temporary bond portion, followed by temporary bonding with a support substrate. Therefore, since the temporary bond portion does not peel off or thermally deform due to the high-temperature heat treatment during electrode formation, temporarily bonded wafers can be manufactured with good yield. Furthermore, in this method, since the temporary bonding is performed using an uncured thermosetting bonding material, the removal of the support substrate is also easier.

[0045] The present invention will now be described in more detail with reference to the figures, but the present invention is not limited thereto.

[0046] (First Implementation Form) Figures 2 through 8 illustrate a first embodiment of the method for manufacturing a temporarily bonded wafer according to the present invention. In this first embodiment, the epitaxial functional layer is configured to contain an AlGaInP-based material.

[0047] First, a epitaxial substrate is prepared. The epitaxial substrate has a light-emitting element structure as an epitaxial functional layer formed by sequentially growing the following layers after laminating a GaAs buffer layer 102 of a first conductivity type on a GaAs starting substrate 101 of a first conductivity type as shown in FIG. 2: a first etching stop layer 103 of a first conductivity type, Ga yIn 1-yP (0.4 ≦ y ≦ 0.6), for example, 0.3 μm; a second etching stop layer 104 of a first conductivity type, GaAs, for example, 0.3 μm; a first cladding layer 105 of a first conductivity type, (Al xGa 1-x) yIn 1-yP (0 < x ≦ 1, 0.4 ≦ y ≦ 0.6), for example, 1.0 μm; an undoped active layer 106, (Al xGa 1-x) yIn 1-yP (0 ≦ x ≦ 0.6, 0.4 ≦ y ≦ 0.6); a second cladding layer 107 of a second conductivity type, (Al xGa 1-x) yIn 1-yP (0 < x ≦ 1, 0.4 ≦ y ≦ 0.6), for example, 1.0 μm; an intermediate layer 108 of a second conductivity type, Ga yIn 1-yP (0.45 ≦ y ≦ 1), for example, 0.1 μm; and a window layer 109 of a second conductivity type, GaP, for example, 4 μm. Here, the region from the first cladding layer 105 of AlGaInP to the second cladding layer 107 of AlGaInP is referred to as a double heterostructure (DH) section 111 (FIG. 3).

[0048] Then, as shown in FIG. 3, a first electrode 110 is formed in a partial region of the window layer 109 of a second conductivity type, GaP. The first electrode 110 is preferably made of a highly reflective metal, and an Au-based electrode can be used. For example, an AuBe alloy can be used for the metal in contact with the GaP window layer 109, and Au can be laminated thereon to form the first electrode 110.

[0049] The metal in contact with the window layer 109 of a second conductivity type, GaP, is not limited to an AuBe alloy, and any metal / alloy can be selected as long as an ohmic contact can be formed. Generally, in addition to AuBe, alloys such as AuZn are often selected.

[0050] Then, as shown in FIG. 4, after the first electrode 110 is formed, a region other than the region where the first electrode 110 is formed in the window layer 109 of a second conductivity type, GaP, is coated with a material having etching selectivity, such as SiO 2 or SiNx, as a mask, and a notch is formed in the exposed portion by a method such as dry etching to expose the first cladding layer 105 of a first conductivity type, AlGaInP.

[0051] Then, as shown in Figure 5, the second conductivity type GaP window layer 109, the notch side, and the first conductivity type AlGaInP first coating layer 105 are coated with SiO2 or SiNx to form a PSV (passivation) film 113, and a portion of the first electrode 110 and a portion of the first conductivity type AlGaInP first coating layer 105 are exposed by photolithography. Then, a second electrode 112 is formed on the exposed portion of the first conductivity type AlGaInP first coating layer 105.

[0052] The second electrode 112 is preferably made of a highly reflective metal, and can be configured as an Au-based electrode. For example, an AuSi alloy can be used in the metal connected to the first conductive AlGaInP first cladding layer 105, and Au can be deposited on it to form the second electrode 112.

[0053] Furthermore, the metal bonded to the first AlGaInP cladding layer 105 of the first conductivity type is not limited to AuSi alloy; any type of metal / alloy can be selected as long as an ohmic contact can be formed. Generally, in addition to AuSi, alloys such as AuGe are often chosen.

[0054] Furthermore, it is not necessary to form the PSV film 113 before the formation of the second electrode 112; the PSV film 113 can also be formed after the formation of the second electrode 112. Moreover, the same effect can be obtained even if the PSV film 113 itself is not formed.

[0055] After the first / second electrodes 110 and 112 are formed, an RTA (Rapid Thermal Annealing) heat treatment is performed, for example, at 400°C for 5 minutes, in order to obtain ohmic contact. Although the case of RTA treatment is illustrated here, it is not limited to this RTA treatment, and a relatively low temperature treatment, for example, at 350°C for about 30 minutes, may also be performed.

[0056] Then, as shown in Figure 6, after the ohmic contact is formed, BCB resin 114 is spin-coated onto the electrode forming surface side and positioned opposite a support substrate 115 selected from silicon or the like. Pressure is applied in a vacuum environment, and the mixture is held at 150°C for approximately 15 minutes to temporarily bond with the support substrate 115. Since BCB resin 114 hardens when maintained at temperatures exceeding 150°C, maintaining a temperature below 150°C prevents hardening of the BCB resin 114. By keeping the BCB resin 114 unhardened, the peelability of the support substrate 115 from the epitaxial substrate can be improved.

[0057] In addition, the thermosetting bonding material is not limited to benzocyclobutene (BCB) resin, and can also be, for example, polyimide (PI) resin, fluororesin, and epoxy resin.

[0058] In addition, the support substrate 115 is not limited to silicon, and any kind of material can be selected as long as it is a material with good surface flatness. For example, sapphire, GaP, GaAs, InP, quartz, glass, LiTaO3, LiNbO3, crystal, SiC, etc. can be selected.

[0059] Then, after temporarily bonding to the support substrate 115 as shown in Fig. 7, the starting substrate is removed by selective etching. The GaAs starting substrate 101 is removed with an ammonia hydrogen peroxide solution, the GaInP first etch stop layer 103 is removed with a diluted hydrochloric acid or hydrochloric acid-based etchant, and finally the GaAs second etch stop layer 104 is removed with a sulfuric acid hydrogen peroxide solution, exposing the first conductive type AlGaInP first cladding layer 105. The temporarily bonded wafer can be manufactured in the above manner.

[0060] Finally, after the first conductive type AlGaInP first cladding layer 105 of the temporarily bonded wafer is exposed as shown in Fig. 8, it is adhered to a silicon wafer 117 coated with silicon oxide 116, and the softened BCB resin 114 is dissolved with a BCB solution to peel off the support substrate 115, and then singulation is performed.

[0061] (Second Embodiment) The second embodiment of the method for manufacturing a temporarily bonded wafer of the present invention will be described using Figs. 9 to 15. In the second embodiment, the epitaxial functional layer is set to include an InGaN-based material.

[0062] First, an epitaxial substrate is prepared, which has a light-emitting element structure as an epitaxial functional layer formed by sequentially growing the following layers after laminating a first conductive type GaN buffer layer 202 on a sapphire starting substrate 201 as shown in Fig. 9: a first conductive type GaN first cladding layer 203, for example, 1.0 μm, an undoped InzGa1 - zN (0 < z ≤ 0.4) active layer 204, a second conductive type AlvGa1 - vN (0 ≤ v ≤ 0.4) (GaN) second cladding layer 205, for example, 1.0 μm, and a second conductive type GaN contact layer 206, for example, 0.1 μm. Here, the portion from the GaN first cladding layer 203 to the AlGaN second cladding layer 205 is referred to as a double heterojunction (DH) structure portion 208 (Fig. 10).

[0063] Then, as shown in Figure 10, a first electrode 207 is formed in a portion of the GaN contact layer 206 of the second conductivity type. The first electrode 207 is preferably made of a highly reflective metal, and can be configured as an Ag-based electrode. For example, Ag can be used in the metal in contact with the GaN contact layer 206, and Pd can be deposited on it to form the first electrode 207.

[0064] Furthermore, the metal bonded to the GaN contact layer 206 of the second conductivity type is not limited to Ag-based metals; any type of metal / alloy can be selected as long as an ohmic contact can be formed. Generally, in addition to Ag, metals such as Au and Ti are often chosen.

[0065] Then, as shown in Figure 11, after the first electrode 207 is formed, a part of the area outside the area where the first electrode 207 of the second conductivity GaN contact layer 206 is formed is covered by a material with etching selectivity such as SiO2 or SiNx, and the exposed part is formed with a notch by dry etching or other methods, so that the first conductivity GaN first covering layer 203 is exposed.

[0066] Then, as shown in Figure 12, the GaN contact layer 206, the side of the notch, and the GaN first coating layer 203 are covered with SiO2 or SiNx to form a PSV film 210, and the first electrode 207 and a portion of the GaN first coating layer 203 are exposed by photolithography. The second electrode 209 is formed on the exposed portion of the GaN first coating layer 203.

[0067] Furthermore, the second electrode 209 is preferably made of a highly reflective metal, and can be an Al-based electrode. For example, Al metal can be used as the metal in contact with the first GaN cladding layer 203 of the first conductivity type, and Au can be deposited on it to form the second electrode 209.

[0068] Furthermore, the metal bonded to the GaN first cladding layer 203 of the first conductivity type is not limited to Al metal; any type of metal / alloy can be selected as long as an ohmic contact can be formed. Generally, in addition to Al, metals such as Ti and Au are often chosen.

[0069] Furthermore, it is not necessary to form the PSV film 210 before the formation of the second electrode 209; the PSV film 210 can also be formed after the formation of the second electrode 209. Moreover, the same effect can be obtained even if the PSV film 210 itself is not formed.

[0070] After the first / second electrodes 207 and 209 are formed, an RTA heat treatment is performed, for example, at 700°C for 5 minutes, in order to obtain ohmic contact.

[0071] Then, as shown in Figure 13, after the ohmic contact is formed, BCB resin 211 is spin-coated onto the electrode forming surface side and positioned opposite a support substrate 212 selected from silicon or the like. Pressure is applied in a vacuum environment, and the substrate is held at 150°C for approximately 15 minutes to temporarily bond with the support substrate 212. Since BCB resin 211 hardens when kept at temperatures exceeding 150°C, maintaining a temperature below 150°C prevents hardening of the BCB resin 211. By keeping the BCB resin 211 unhardened, the peelability of the support substrate 212 from the epitaxial substrate can be improved.

[0072] Furthermore, thermosetting bonding materials are not limited to benzocyclobutene (BCB) resins, but can also be, for example, polyimide (PI) resins, fluororesins, and epoxy resins.

[0073] Furthermore, the support substrate 212 is not limited to silicon; any type of material can be selected as long as it has good surface flatness. Examples of suitable materials include: sapphire, GaP, GaAs, InP, quartz, glass, LiTaO3, LiNbO3, crystal, SiC, etc.

[0074] Then, as shown in Figure 14, after temporary bonding, a laser is irradiated from the starting substrate side to ablate the GaN buffer layer 202, thereby removing the sapphire starting substrate 201 and exposing the first GaN cladding layer 203 of the first conductivity type. Temporary bonding wafers can be manufactured in this manner.

[0075] Finally, as shown in Figure 15, after the first GaN cladding layer 203 of the first conductivity type is exposed, it is adhered to the silicon wafer 214 coated with silicon oxide 213, and the support substrate 212 is peeled off by dissolving the softened BCB resin 211 with BCB solvent, and then monolithization is performed. [Example]

[0076] Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited thereto.

[0077] (Example 1) A epitaxial substrate is prepared. The epitaxial substrate has a light-emitting element structure as an epitaxial functional layer formed by sequentially growing the following layers after laminating a GaAs buffer layer of a first conductivity type on a GaAs starting substrate of a first conductivity type: a first conductivity type Ga yIn 1-yP (0.4 ≦ y ≦ 0.6) first etching stop layer of 0.3 μm, a first conductivity type GaAs second etching stop layer of 0.3 μm, a first conductivity type (Al xGa 1-x) yIn 1-yP (0 < x ≦ 1, 0.4 ≦ y ≦ 0.6) first cladding layer of 1.0 μm, an undoped (Al xGa 1-x) yIn 1-yP (0 ≦ x ≦ 0.6, 0.4 ≦ y ≦ 0.6) active layer, a second conductivity type (Al xGa 1-x) yIn 1-yP (0 < x ≦ 1, 0.4 ≦ y ≦ 0.6) second cladding layer of 1.0 μm, a second conductivity type Ga yIn 1-yP (0.45 ≦ y ≦ 1) intermediate layer of 0.1 μm, and a second conductivity type GaP window layer of 4 μm (refer to FIG. 2).

[0078] Then, a first electrode is formed in a partial region of the second conductivity type GaP window layer. The first electrode is preferably a highly reflective metal, and an Au-based electrode is used. In the present technology, an AuBe alloy is used for the metal in contact with the GaP window layer, and Au is laminated thereon to form the first electrode (refer to FIG. 3).

[0079] After forming the first electrode, a part of the region other than the first electrode formation region of the second conductivity type GaP window layer is coated with SiO 2, and a notch is formed by dry etching of the exposed portion to expose the first conductivity type AlGaInP first cladding layer (refer to FIG. 4).

[0080] The second conductivity type GaP window layer, the side surface of the notch portion, and the first conductivity type AlGaInP first cladding layer are coated with SiO 2 as a PSV film, and a part of the first electrode portion and the first conductivity type AlGaInP first cladding layer is exposed by photolithography. Then, a second electrode is formed on the exposed portion on the first conductivity type AlGaInP first cladding layer. Here, for the metal in contact with the first conductivity type AlGaInP first cladding layer, an AuSi alloy is used, and Au is laminated thereon to form (refer to FIG. 5).

[0081] After the first / second electrodes are formed, an RTA treatment at 400 °C for 5 minutes is performed to obtain an ohmic contact.

[0082] After the ohmic contact is formed, BCB resin is spin-coated on the side of the electrode formation surface, and it is opposed to a support substrate made of silicon, and pressure is applied in a vacuum environment, and it is kept at 150 °C for about 15 minutes to temporarily bond to the support substrate (refer to Fig. 6).

[0083] After being temporarily bonded to the support substrate, the GaAs starting substrate is removed with an ammonia hydrogen peroxide solution, the GaInP first etch stop layer is removed with a diluted hydrochloric acid or hydrochloric acid-based etchant, and finally the GaAs second etch stop layer is removed with a sulfuric acid hydrogen peroxide solution, and the first conductive type AlGaInP first cladding layer is exposed (refer to Fig. 7).

[0084] After the first conductive type AlGaInP first cladding layer is exposed, it is adhered to a silicon wafer coated with silicon oxide, and the softened BCB resin is dissolved with a BCB dissolving solution to peel off the support substrate, and then singulation is performed (refer to Fig. 8).

[0085] (Example 2) A epitaxial substrate is prepared, which has a light-emitting element structure as an epitaxial functional layer formed by sequentially growing the following layers after laminating a first conductive type GaN buffer layer on a sapphire starting substrate: a first conductive type GaN first cladding layer of 1.0 μm, an undoped In zGa 1-zN (0 < z ≤ 0.4) active layer, a second conductive type Al vGa 1-vN (0 ≤ v ≤ 0.4) (GaN) second cladding layer of 1.0 μm, and a second conductive type GaN contact layer of 0.1 μm (refer to Fig. 9).

[0086] Then, in a part of the region of the second conductive type GaN contact layer, Ag is used as the metal in contact with the GaN contact layer, and Pd is laminated thereon to form a first electrode (refer to Fig. 10).

[0087] After the first electrode is formed, a part of the region other than the first electrode formation region of the second conductive type GaN contact layer is coated with SiO 2, and a notch is formed by dry etching the exposed part, and the first conductive type GaN first cladding layer is exposed (refer to Fig. 11).

[0088] The GaN contact layer, the side surface of the notch, and the GaN first coating layer are coated with SiO2 to form a PSV film, and a part of the first electrode portion and the GaN first coating layer is exposed by photolithography. On the exposed portion on the GaN first coating layer, Al metal is used as the metal in contact with the first-conductive-type GaN first coating layer, and Au is laminated thereon to form a second electrode (refer to Fig. 12).

[0089] After the first / second electrodes are formed, an RTA heat treatment at 700 °C for 5 minutes is performed to obtain an ohmic contact.

[0090] After the ohmic contact is formed, a BCB resin is spin-coated on the electrode formation surface side, and it is opposed to a support substrate made of silicon, and pressure is applied in a vacuum environment, and it is held at 150 °C for about 15 minutes to be temporarily bonded to the support substrate (refer to Fig. 13).

[0091] After the temporary bonding, the GaN buffer layer is ablated by irradiating a laser from the starting substrate side, and the starting substrate is removed, and the first-conductive-type GaN first coating layer is exposed (refer to Fig. 14).

[0092] After the first-conductive-type GaN coating layer is exposed, it is adhered to a silicon wafer coated with silicon oxide, and the softened BCB resin is dissolved with a BCB dissolving solution to peel off the support substrate, and then singulation is performed (refer to Fig. 15).

[0093] (Comparative Example) Aepitaxial substrate is prepared, which has a light-emitting element structure as an epitaxial functional layer formed by sequentially growing the following layers after laminating a first-conductive-type GaAs buffer layer on a first-conductive-type GaAs starting substrate: a first-conductive-type Ga yIn 1-yP (0.4 ≤ y ≤ 0.6) first etching stop layer of 0.3 μm, a first-conductive-type GaAs second etching stop layer of 0.3 μm, a first-conductive-type (Al xGa 1-x) yIn 1-yP (0 < x ≤ 1, 0.4 ≤ y ≤ 0.6) first coating layer of 1.0 μm, an undoped (Al xGa 1-x) yIn 1-yP (0 ≤ x ≤ 0.6, 0.4 ≤ y ≤ 0.6) active layer, a second-conductive-type (Al xGa 1-x) yIn 1-yP (0 < x ≤ 1, 0.4 ≤ y ≤ 0.6) second coating layer of 1.0 μm, a second-conductive-type Ga yIn 1-yP (0.45 ≤ y ≤ 1) intermediate layer of 0.1 μm, and a second-conductive-type GaP window layer of 4 μm (refer to Fig. 2).

[0094] A 1.0 μm layer of BCB resin is spin-coated onto an epitaxial substrate and stacked face-to-face with a sapphire wafer, followed by hot pressing to create an epitaxial bonding substrate. This epitaxial bonding substrate is formed by bonding the epitaxial substrate and the sapphire wafer using BCB. During bonding, the substrate is held at 250°C for 1 hour for curing.

[0095] The GaAs starter substrate is removed using an ammonia-hydrogen peroxide solution, exposing the first GaInP etch stop layer. The etchant is then switched to a hydrochloric acid-based solution to remove the first GaInP etch stop layer, exposing the second GaAs etch stop layer. Finally, the etchant is switched to a sulfuric acid-hydrogen peroxide-based solution to remove the second GaAs etch stop layer, exposing the first coating layer. By performing these processes, an epitaxial bonding substrate is fabricated that retains only the dual heterolayer and window layer.

[0096] After the initial substrate is removed, an AuBe-based metal is used on the metal in contact with the surface of the initial substrate (first cladding layer), and Au is deposited thereon to form the first electrode.

[0097] After the first electrode is formed, a notch is formed in a portion of the area outside the first electrode formation area of ​​the first coating layer by means of dry etching or other methods, so that the second coating layer is exposed in the notch.

[0098] A passivation (PSV) film is used to cover the first AlGaInP coating layer, the side of the notch, and the second AlGaInP coating layer. A photolithography method is then used to expose the first electrode portion and a portion of the second AlGaInP coating layer. A second electrode made of Au is then formed on the exposed portion of the second coating layer.

[0099] After the first / second electrode is formed, an RTA treatment is performed at 400°C for 5 minutes to obtain ohmic contact.

[0100] After being attached to a silicon oxide-coated wafer, the substrate is irradiated with a laser from the support substrate side to ablate it, thus separating the support substrate from the device.

[0101] (Comparison of results between the exemplary and comparative examples) For the temporary bonded wafers prepared in Examples 1, 2 and Comparative Examples, the area yield, doping level, area yield when using P-CVD (plasma-chemical vapor deposition), and leakage defect rate are compared as follows.

[0102] [Area Finishing Rate] Table 1 shows a comparison of yield (the proportion of bonded area). In Examples 1 and 2, since the electrode formation step and the component separation step were completed before the temporary bonding, the temporary bonding portion did not peel off / deform due to ohmic heat treatment. Therefore, the steps could be performed on a wafer with good flatness and warpage, and the yield during the electrode formation and component separation steps could be maintained at the same level as that of the unbonded wafer. On the other hand, in the comparative example, since the wafer with the temporary bonding portion was subjected to high-temperature RTA heat treatment, the temporary bonding portion peeled off / deformed, and a sufficient yield could not be obtained.

[0103] [Table 1] Example 1 Example 2 Comparative example Effective area 97%~99% 96%~99% 10~47%

[0104] [Doping Level] Even after hardening, BCB films lose their bonding strength if the softening point is exceeded, making high-temperature processing impossible. To form ohmic contacts, one of the following methods is required: processing at temperatures exceeding the BCB softening point; or making the metal contact layer highly doped to avoid high-temperature processing. However, heat treatment exceeding the BCB softening point easily induces deformation of the BCB bonding layer, leading to a decrease in device yield. On the other hand, making the contact layer highly doped easily induces device degradation during current flow due to electromigration effects, resulting in performance degradation. Performing electrode formation / device separation steps on the wafer before BCB bonding layer formation avoids the aforementioned thermal limitations and epitaxial substrate design limitations, increasing design freedom and preventing device quality degradation due to process limitations.

[0105] Table 2 shows the required doping levels for the first and second electrode contact layers in Examples 1 and 2, as well as the comparative example. In the examples, since high-temperature processing can be performed during electrode formation, ohmic contacts can be obtained with a doping level on the 17th power order. On the other hand, in the comparative example, since the wafer containing the BCB temporary junction is subjected to ohmic heat treatment for electrode formation, the temporary junction will peel off if high-temperature processing is performed. Therefore, in the comparative example, if a high yield is maintained, heat treatment must be performed at a low temperature, thus requiring a doping level on the 18th power order.

[0106] When a coating layer with a doping level of 18 is formed, defects are easily generated in the active layer due to electromigration during power-on, making the device highly likely to degrade under power. Light-emitting devices with 18-level doping only meet quality standards in the initial stages, but fail to meet quality standards in the transition characteristics. In the embodiments, since an epitaxial layer with a doping level one lower can be used, the problem of unsatisfactory transition characteristics that occurred in the comparative examples can be avoided.

[0107] [Table 2] Example 1 Example 2 Comparative example First electrode contact layer 1~5E+17[ / cm 3] 1~3E+17[ / cm 3] 1~2E+18[ / cm 3] Second electrode contact layer 1~5E+17[ / cm 3] 1~5E+17[ / cm 3] 1~2E+18[ / cm 3]

[0108] [Area yield when using P-CVD] To form SiO2 as a PSV film, film deposition methods such as P-CVD are required, necessitating a thermal environment above 400°C due to the material's reactive properties. When P-CVD is used for film deposition after BCB bonding (comparative example), film deposition must be performed at the softening point of BCB, and deformation of the BCB film easily occurs during deposition. This deformation of the BCB film becomes significant as epitaxial layer lift-off (peeling), and the yield decreases because the lifted portion eventually peels off.

[0109] Table 3 shows the yield (percentage of adhesive area) at the start of the P-CVD step. As shown in Table 3, a high yield was obtained in the examples. In contrast, the comparative examples performed the PSV film formation step after temporary bonding, and the bonding peeled off during the PSV film formation step, resulting in a lower yield.

[0110] [Table 3] Example 1 Example 2 Comparative example Effective area 97%~100% 95%~100% 16~68%

[0111] [Defect rate] Furthermore, if the PSV film is merely a hard mask, film formation methods other than P-CVD, such as physical film formation, can be selected. However, in PSV film formation, physical film formation suffers from poor coverage of the side surfaces, resulting in the inability to suppress leakage at the side surfaces.

[0112] Therefore, as shown in Table 4, the comparative examples could not use the optimal P-CVD method in PSV film formation, while Examples 1 and 2 could use the P-CVD method. In this case, the leakage defect rate of the comparative examples was higher than that of Examples 1 and 2.

[0113] [Table 4] Example 1 Example 2 Comparative example Leakage defect rate 0.01%~3.75% 0.01%~4.11% 58~100%

[0114] Furthermore, the present invention is not limited to the above-described embodiments. The above-described embodiments are merely illustrative, and any embodiment that has a substantially identical structure and produces the same effect as the technical concept described in the claims of the present invention is included within the technical scope of the present invention.

[0115] 1: Epitaxial functional layer 2: Electrode 3,115,212: Support substrate 4: Uncured thermosetting bonding materials 100: Temporarily bonded wafer 101: GaAs initiation substrate of the first conductivity type 102: GaAs buffer layer of the first conductivity type 103: First Etching Stop Layer 104: Second etch stop layer of GaAs with first conductivity type 105: First conductivity type (Al xGa 1-x) yIn 1-yP first cladding layer 106: Undoped (Al xGa 1-x)yIn 1-yP active layer 107: Second conductivity type (Al xGa 1-x) yIn 1-yP second cladding layer 108: Second conductivity type Ga yIn 1-yP interlayer 109: GaP window layer of the second conductivity type 110,207: First electrode 111,208: Dual heterogeneous structure 112,209: Second electrode 113,210: PSV film 114,211: BCB resin 116,213: Silicon Oxide 117,214: Silicon wafers 201: Sapphire starter substrate 202: GaN buffer layer of the first conductivity type 203: First GaN cladding layer of the first conductivity type 204: Undoped In zGa 1-zN active layer 205: Al vGa 1-vN second cladding layer of the second conductivity type 206: GaN contact layer of the second conductivity type

[0116] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A temporarily bonded wafer, characterized in that: it is formed by temporarily bonding an epitaxial functional layer to a support substrate, wherein one side of the epitaxial functional layer has two or more electrodes with different polarities, and the temporarily bonded wafer is formed by temporarily bonding the side of the epitaxial functional layer having the aforementioned electrodes to the aforementioned support substrate via an uncured thermosetting bonding material, wherein the aforementioned thermosetting bonding material is any one of benzocyclobutene (BCB) resin, polyimide (PI) resin, fluororesin, and epoxy resin.

2. The temporarily bonded wafer as described in claim 1, wherein, The aforementioned epitaxial functional layer is a light-emitting element.

3. The temporarily bonded wafer as described in claim 1, wherein, The aforementioned epitaxial functional layer contains AlGaInP or InGaN-based materials.

4. The temporarily bonded wafer as described in claim 2, wherein, The aforementioned epitaxial functional layer contains AlGaInP or InGaN-based materials.

5. The temporarily bonded wafer as claimed in any one of claims 1 to 4, wherein, The aforementioned support substrate is made of any one of the following materials: silicon, sapphire, GaP, GaAs, InP, SiC, quartz, glass, LiTaO3, and LiNbO3.

6. The temporarily bonded wafer as claimed in any one of claims 1 to 4, wherein, The side of the aforementioned epitaxial functional layer opposite to the side with the aforementioned electrode does not have a starting substrate.

7. A method for manufacturing a temporarily bonded wafer, characterized in that: it is a method for temporarily bonding an epitaxial substrate to a support substrate, wherein the epitaxial substrate is formed by growing an epitaxial functional layer on a starting substrate, and includes: (1) The step of forming two or more electrodes with different polarities on one side of the aforementioned epitaxial functional layer of the aforementioned epitaxial substrate; (2) The step of temporarily bonding the aforementioned support substrate to the surface on which the aforementioned electrode is formed by means of an uncured thermosetting bonding material, wherein the aforementioned thermosetting bonding material is any one of benzocyclobutene (BCB) resin, polyimide (PI) resin, fluororesin and epoxy resin.

8. The method for manufacturing a temporarily bonded wafer as described in claim 7, wherein the aforementioned epitaxial functional layer is configured as a light-emitting element.

9. The method for manufacturing a temporary bonded wafer as described in claim 7, wherein the aforementioned epitaxial functional layer comprises an AlGaInP-based or InGaN-based material.

10. The method for manufacturing a temporarily bonded wafer as described in claim 8, wherein the aforementioned epitaxial functional layer comprises an AlGaInP-based or InGaN-based material.

11. A method for manufacturing a temporary bonded wafer as claimed in any one of claims 7 to 10, wherein the aforementioned support substrate is made of any one of silicon, sapphire, GaP, GaAs, InP, SiC, quartz, glass, LiTaO3 and LiNbO3.

12. A method for manufacturing a temporary bonded wafer as claimed in any one of claims 7 to 10, further comprising, after the aforementioned step (2): (3) a step of removing the aforementioned starting substrate from the aforementioned epitaxial substrate.

Images