Composite substrate, method for manufacturing a composite substrate

Abstract

The composite substrate has a functional substrate configured to include at least one of a crystal of InP and a crystal of a material capable of being formed by epitaxial growth on a crystal of InP, and a support substrate composed of a semiconductor material, which supports the functional substrate by being joined to the functional substrate. The functional substrate has a first layer and a second layer disposed on the side closer to the support substrate than the first layer, which is composed of an amorphous body containing a rare gas element. The support substrate has a first support layer, a second support layer disposed on the side closer to the functional substrate than the first support layer, which is composed of an amorphous body of a semiconductor material containing a rare gas element, and a joining layer in contact with the functional substrate, which is composed of an amorphous body of a semiconductor material.

Description

Technical Field

[0001] This invention relates to composite substrates and their manufacturing methods. Background Technology

[0002] Previously, a composite substrate was known, which was formed by bonding a functional substrate made of InP (indium phosphide) with a support substrate made of semiconductor materials such as Si and SiC. This substrate is used in photonic devices such as semiconductor lasers, photodiodes, and modulators, as well as high-frequency transistors such as HEMT (High Electron Mobility Transistors) and HBT (Heterojunction Bipolar Transistors). A known method for fabricating such a composite substrate involves activating each bonding surface of the functional substrate and the support substrate by irradiating them with a fast atomic beam (FAB), and then directly bonding these bonding surfaces together. However, in this method, P is selectively sputtered on the InP substrate side, forming an In layer on the surface. This results in the problem that the In layer on the surface easily peels off from the InP substrate, reducing the bonding strength of the composite substrate (see Non-Patent Literature 1).

[0003] Therefore, as a technology to solve the above-mentioned problem, the technology of Patent Document 1 is known. Patent Document 1 discloses the following approach: forming an indium oxide barrier layer on an InP substrate, and bonding the barrier layer and the silicon substrate by means of an amorphous layer. By means of this method, the barrier layer can prevent high-speed atomic beams from directly irradiating the InP substrate, thereby suppressing the formation of an In layer on the surface, and thus obtaining sufficient bonding strength without peeling.

[0004] Existing technical documents

[0005] Non-patent literature

[0006] Non-patent literature 1: MMR Howlader, T. Watanabe, and T. Suga, "Characterization of the bonding strength and interface current of p-Si / n-InPwafers bonded by surface activated bonding method at room temperature", JOURNAL OF APPLIED PHYSICS, VOLUME 91, NUMBER 5, p. 3062-3066

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2023-500 Summary of the Invention

[0009] In recent years, photonic devices and high-frequency transistors constructed using InP composite substrates have demanded miniaturization, high integration, and high output, leading to an increasing heat density per unit area. If the InP temperature rises excessively during operation, these devices cannot achieve the desired performance and also suffer from reduced reliability and lifespan. Therefore, a structure is needed to efficiently dissipate heat from the device. However, in the composite substrate structure of Patent Document 1, the presence of a barrier layer with low thermal conductivity at the bonding interface makes it difficult to efficiently dissipate heat generated in the InP substrate to the support substrate side.

[0010] In addition, in recent years, components consisting of photonic devices, high-frequency transistors, and other devices have been practically fabricated on composite substrates formed by bonding a substrate containing semiconductor material grown epitaxially on an InP crystal with a support substrate. In such composite substrates, it is also necessary to design a structure that allows the heat from the device to be efficiently dissipated to the support substrate side.

[0011] The present invention was made in view of the above, and its main objective is to realize a composite substrate and a method thereof that enables the heat of the functional substrate to be efficiently dissipated to the support substrate side, based on a composite substrate obtained by bonding a functional substrate containing InP or a crystal of a material that can be formed by epitaxial growth on a crystal of InP and a support substrate by means of a bonding layer.

[0012] The composite substrate of the present invention comprises: a functional substrate comprising at least one of InP and a crystalline material that can be formed by epitaxial growth on a crystalline InP; and a support substrate made of a semiconductor material, bonded to the functional substrate to support the functional substrate, the functional substrate having a first layer and a second layer, the second layer being disposed closer to the support substrate than the first layer and being made of an amorphous body containing a rare gas element; the support substrate comprising: a first support layer; a second support layer being disposed closer to the functional substrate than the first support layer and being made of an amorphous body of the semiconductor material containing the rare gas element; and a bonding layer being in contact with the functional substrate and being made of an amorphous body of the semiconductor material.

[0013] One aspect of the present invention relates to a method for manufacturing a composite substrate: a method for manufacturing a composite substrate comprising a functional substrate made of InP and a support substrate made of a semiconductor material supporting the functional substrate, comprising the following steps: an oxide film removal and activation step, wherein a high-speed atomic beam is irradiated onto an InP oxide film formed on the surface of the functional substrate and the surface of the semiconductor substrate made of the semiconductor material, respectively, to remove at least a portion of the oxide film and to activate the surfaces of the functional substrate and the semiconductor substrate; a sputtering step, following the oxide film removal and activation step, wherein after stopping the irradiation of the surface of the functional substrate with the high-speed atomic beam, the high-speed atomic beam is continued to irradiate the surface of the semiconductor substrate to sputter the semiconductor material onto the surface of the functional substrate; and a bonding step, wherein the functional substrate and the semiconductor substrate sputtered with the semiconductor material in the sputtering step are bonded together to obtain a bonded body.

[0014] Another aspect of the present invention relates to a method for manufacturing a composite substrate: a method comprising a functional substrate having a material formed by epitaxial growth on a crystal of InP, and a support substrate made of a semiconductor material supporting the functional substrate, the method comprising the following steps: an oxide film removal and activation step, wherein a high-speed atomic beam is irradiated onto an oxide film of the material formed on the surface of the functional substrate and onto the surface of a semiconductor substrate made of the semiconductor material, respectively, to remove at least a portion of the oxide film and to activate the surfaces of the functional substrate and the semiconductor substrate; a sputtering step, wherein, following the oxide film removal and activation step, the high-speed atomic beam irradiation of the surface of the functional substrate is stopped, and the high-speed atomic beam irradiation of the surface of the semiconductor substrate is continued to sputter the semiconductor material onto the surface of the functional substrate; and a bonding step, wherein the functional substrate and the semiconductor substrate sputtered with the semiconductor material in the sputtering step are bonded together to obtain a bonded body.

[0015] Invention Effects

[0016] According to the present invention, based on a composite substrate obtained by bonding a functional substrate containing InP or a material crystal formed by epitaxial growth on a crystal of InP and a support substrate by means of a bonding layer, a composite substrate capable of efficiently dissipating heat from the functional substrate to the support substrate side and a method thereof can be realized. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the first embodiment of the present invention.

[0018] Figure 2This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the first embodiment of the present invention.

[0019] Figure 3 This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the first embodiment of the present invention.

[0020] Figure 4 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the second embodiment of the present invention.

[0021] Figure 5 This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the second embodiment of the present invention.

[0022] Figure 6 This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the second embodiment of the present invention.

[0023] Figure 7 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the third embodiment of the present invention.

[0024] Figure 8 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the fourth embodiment of the present invention.

[0025] Figure 9 These are photographs showing observations of the embodiments and comparative examples.

[0026] Figure 10 This table summarizes the FAB irradiation time, presence or absence of peeling at the bonding interface during processing, oxide film thickness, and distance between Ar peaks in each of the examples and comparative examples.

[0027] Figure 11 This is a graph showing the relationship between FAB irradiation time and Ar peak distance for a functional substrate when the support substrate is made of SiC.

[0028] Figure 12 This is a graph showing the relationship between FAB irradiation time and Ar peak distance for a functional substrate when the support substrate is made of Si. Detailed Implementation

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings; however, the present invention is not limited to these embodiments. Furthermore, to make the description clearer, the drawings sometimes schematically show the width, thickness, shape, etc., of each part compared to the embodiments; however, this is merely an example and does not limit the interpretation of the present invention.

[0030] (First Implementation)

[0031] Figure 1 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the first embodiment of the present invention. The composite substrate 100 in this embodiment is used for various applications such as semiconductor lasers, photodiodes, modulators and other photonic devices, HEMTs, HBTs and other high-frequency transistors, and has a structure in which a functional substrate 1 having an InP layer 10 and an oxide film 20 is bonded to a support substrate 30.

[0032] The material of the functional substrate 1 is, for example, a crystalline form of InP. A portion of the crystalline structure in the InP layer 10 is transformed into an amorphous form during the manufacturing process of the composite substrate 100, and is included in the InP layer 10 in an amorphous state. This will be explained below.

[0033] The oxide film 20 is an oxide layer formed on the surface of the InP layer 10 by the natural oxidation of a portion of the InP constituting the InP layer 10 in the air before the functional substrate 1 is bonded to the support substrate 30, and is disposed between the InP layer 10 and the support substrate 30 in the composite substrate 100.

[0034] The support substrate 30 supports the functional substrate 1, which includes the InP layer 10 and the oxide film 20. Any suitable substrate can be used as the support substrate 30. The support substrate 30 can be made of a single crystal or a polycrystalline material. The oxide film 20 of the functional substrate 1 and the support substrate 30 are directly bonded to each other.

[0035] The material constituting the support substrate 30 can be a semiconductor material such as SiC or Si. Alternatively, AlN, diamond, SOI (Silicon on Insulator), etc., can be used to constitute the support substrate 30. When SOI is used as the support substrate 30, the SOI substrate (support substrate 30) can include optical circuits, circuits, etc., made of Si. The thickness of the support substrate 30 is, for example, 0.2 to 1 mm, but any other suitable thickness can be used.

[0036] It should be noted that, although not shown in the figure, the composite substrate 100 may further have any layers. The type, function, number, combination, and configuration of such layers can be appropriately set according to the purpose.

[0037] The composite substrate 100 can be manufactured in any suitable shape. In one embodiment, the composite substrate 100 can be manufactured in the form of a so-called wafer. In addition, the size of the composite substrate 100, for example, the diameter of the wafer (substrate) is 50 mm to 150 mm, can be appropriately set according to the purpose.

[0038] Figure 2 and Figure 3This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the first embodiment of the present invention.

[0039] Figure 2 (a) shows a preparation step in the manufacturing process of the composite substrate 100. In this step, a functional substrate 1 made of InP crystals of a specified thickness is prepared. The functional substrate 1 has: an InP layer 10 made of InP crystals, and an InP oxide film 20 formed on the surface of the InP layer 10 based on natural oxidation.

[0040] Figure 2 (b) shows the oxide film removal and activation process in the manufacturing process of the composite substrate 100. In this process, for example, a semiconductor substrate 30A of a specified thickness made of semiconductor material is prepared, targeting... Figure 2 In the preparation step (a), the surfaces of the functional substrate 1 and the semiconductor substrate 30A are irradiated for a predetermined time with a high-speed atomic beam (hereinafter referred to as FAB) using a rare gas such as Ar. This removes a portion of the oxide film 20 in the functional substrate 1, thinning it, and activates the surfaces of both the functional substrate 1 and the semiconductor substrate 30A. The preferred irradiation time for the FAB is, for example, about 5 to 12 seconds.

[0041] Figure 2 (c) shows the sputtering process in the manufacturing process of the composite substrate 100. In this process, regarding... Figure 2 In step (b), during the oxide film removal and activation process, the FAB irradiation of the functional substrate 1 and the semiconductor substrate 30A is stopped, while the FAB irradiation of the semiconductor substrate 30A is continued for a predetermined time. The preferred irradiation time for the FAB is, for example, approximately 30 to 600 seconds. As a result, the semiconductor material constituting the semiconductor substrate 30A is sputtered and adheres to the surface of the functional substrate 1 (oxide film 20), forming a sputtered film 30B on the functional substrate 1 side, composed of the same semiconductor material as the semiconductor substrate 30A.

[0042] Figure 3 (d) shows the bonding process in the manufacturing process of the composite substrate 100. In this process, the bonding process is performed on the composite substrate 100. Figure 2 In the sputtering process of (c), the functional substrate 1 on which the sputtered film 30B is formed is bonded to the semiconductor substrate 30A. Thus, the semiconductor substrate 30A and the sputtered film 30B are integrated to form a support substrate 30, resulting in a bond of the functional substrate 1 and the support substrate 30.

[0043] Figure 3 (e) in the middle shows Figure 3 The joined body obtained after the joining process (d) in step (d). Utilizing Figure 3In the bonding process (d) described above, the semiconductor substrate 30A and the sputtered film 30B are integrated, thereby forming a support substrate 30 with their bonding interface 40 inside, resulting in a substrate like... Figure 3 Such a joint as (e) in the example.

[0044] Figure 3 In the bonding assembly (e), a first functional layer 11 and a second functional layer 12 are formed on the InP layer 10 of the functional substrate 1, and are disposed closer to the supporting substrate 30 than the first functional layer 11. The first functional layer 11 is mainly composed of crystalline InP, and the second functional layer 12 is mainly composed of amorphous InP. The second functional layer 12 contains: Figure 2 In (b), the oxide film is removed from the layer of rare gas atoms such as Ar irradiated in the form of FAB during the activation process.

[0045] in addition, Figure 3 In the bonding assembly (e), a first support layer 31 that does not contact the bonding interface 40 is formed on the support substrate 30; a second support layer 32 that is configured to contact the bonding interface 40 from the side of the functional substrate 1 that is closer to the first support layer 31; and a bonding layer 33 that is configured to contact the bonding interface 40 from the side of the functional substrate 1 that is closer to the second support layer 32. The second support layer 32 is: mainly composed of an amorphous body of semiconductor material and containing... Figure 2 Oxide film removal and activation process in (b) Figure 2 In the sputtering process of (c), there is a layer of rare gas atoms such as Ar irradiated in the form of FAB. The bonding layer 33 is a layer that corresponds to the sputtered film 30B before bonding and forms a bonding portion with the functional substrate 1.

[0046] It should be noted that the second functional layer 12 in the functional substrate 1, the second support layer 32 in the support substrate 30, and the bonding layer 33 sometimes contain... Figure 2 Other atomic species, such as Fe atoms and Al atoms, are mixed into these layers during the sputtering process in (c).

[0047] Figure 3 (f) shows the thin-plate processing step in the manufacturing process of the composite substrate 100. In this step, for Figure 3 The bonding assembly shown in (e) thins the InP layer 10 of the functional substrate 1 by grinding it to a specified thickness. For example, grinding, CMP (Chemical Mechanical Polishing), or surface planarization using a gas cluster ion beam can be used to grind the InP layer 10 to achieve thinning.

[0048] Using the above processes, manufacture Figure 1The composite substrate 100 with the structure shown.

[0049] It should be noted that it is possible to Figure 3 The joining process in (d) and Figure 3 An annealing process, in which the bond is heated to a predetermined temperature, is performed between the sheet metal processing steps (f) in the process. The heating temperature is preferably, for example, around 75 to 250°C, and more preferably 100 to 250°C. This improves the bonding strength of the composite substrate 100.

[0050] (Second Implementation)

[0051] Figure 4 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the second embodiment of the present invention. The composite substrate 110 in this embodiment is different from that described in the first embodiment. Figure 1 The composite substrate 100 has a structure in which no oxide film 20 is disposed between the InP layer 10 and the support substrate 30. That is, the composite substrate 110 has a functional substrate 1a made of InP layer 10 but without oxide film 20, replacing the functional substrate 1 in the composite substrate 100.

[0052] It should be noted that, similar to the first embodiment described above, the composite substrate 110 may further have any number of layers. The type, function, number, combination, and arrangement of such layers can be appropriately set according to the purpose. In addition, the composite substrate 110 can be manufactured in any suitable shape according to the purpose.

[0053] Figure 5 and Figure 6 This is a diagram illustrating an example of the manufacturing process of the composite substrate according to the second embodiment of the present invention.

[0054] Figure 5 (a) shows a preparation step in the manufacturing process of the composite substrate 110. This step is similar to that described in the first embodiment. Figure 2 Similarly, in step (a), a functional substrate 1 of a specified thickness made of InP crystals is prepared. The functional substrate 1 has: an InP layer 10 made of InP crystals, and an InP oxide film 20 formed on the surface of the InP layer 10 based on natural oxidation.

[0055] Figure 5 (b) shows the oxide film removal and activation process in the manufacturing process of the composite substrate 110. In this process, the process described in the first embodiment... Figure 2 Similarly, in step (b), a semiconductor substrate 30A made of semiconductor material of a specified thickness is prepared, for example, for... Figure 5In the preparation step (a) of this embodiment, the surfaces of the functional substrate 1 and the semiconductor substrate 30A prepared in the preparation step are irradiated for a predetermined time with a rare gas such as Ar as a seed for FAB. In this embodiment, FAB irradiation of the oxide film 20 is continuously performed until the oxide film 20 in the functional substrate 1 is completely removed, exposing the InP layer 10 on the surface. The irradiation time of the FAB at this time is preferably, for example, about 13 to 24 seconds. Accordingly, a functional substrate 1a containing only the InP layer 10 and not the oxide film 20 is formed from the functional substrate 1 having the InP layer 10 and the oxide film 20.

[0056] Figure 5 (c) shows the sputtering process in the manufacturing process of the composite substrate 110. In this process, the sputtering process is similar to that described in the first embodiment. Figure 2 Similarly, regarding process (c) in the middle, Figure 5 In step (b), during the oxide film removal and activation process, the FAB irradiation on the functional substrate 1 and the semiconductor substrate 30A is stopped, while the FAB irradiation on the semiconductor substrate 30A side is continued for a predetermined time. As a result, the semiconductor material constituting the semiconductor substrate 30A is sputtered and adheres to the surface of the functional substrate 1a, i.e., the surface of the InP layer 10, where the oxide film 20 has been completely removed, forming a sputtered film 30B on the functional substrate 1a side that is made of the same semiconductor material as the semiconductor substrate 30A.

[0057] Figure 6 (d) shows the bonding process in the manufacturing process of the composite substrate 110. In this process, the bonding process described in the first embodiment... Figure 3 Similarly, in process (d), Figure 5 In the sputtering process of (c), the functional substrate 1a with the sputtered film 30B formed and the semiconductor substrate 30A are bonded together. As a result, the semiconductor substrate 30A and the sputtered film 30B are bonded together and integrated to form a support substrate 30, thus obtaining a bonded body of the functional substrate 1a and the support substrate 30.

[0058] Figure 6 (e) in the middle shows Figure 6 The joined body obtained after the joining process (d) in step (d). Utilizing Figure 6 In the bonding process (d) described above, the semiconductor substrate 30A and the sputtered film 30B are integrated, thereby forming a support substrate 30 with their bonding interface 40 inside, resulting in a substrate like... Figure 6 Such a joint as (e) in the example.

[0059] Figure 6 In the assembly of (e) in the first embodiment, Figure 3Similarly, in the bonding assembly (e), a first functional layer 11 and a second functional layer 12 disposed on the functional substrate 1a (InP layer 10) are also formed. Additionally, the support substrate 30 has a first support layer 31 that does not contact the bonding interface 40, a second support layer 32 disposed on the functional substrate 1a side of the first support layer 31 and in contact with the bonding interface 40, and a bonding layer 33 disposed on the functional substrate 1a side of the second support layer 32 and in contact with the bonding interface 40.

[0060] Figure 6 (f) shows the thin-plate processing step in the manufacturing process of the composite substrate 110. In this step, the process described in the first embodiment... Figure 3 Similarly, for process (f) in the middle, Figure 6 The bonding assembly shown in (e) in the figure is made by grinding the functional substrate 1a (InP layer 10) to a specified thickness to achieve thinning.

[0061] Using the above processes, manufacture Figure 4 The composite substrate 110 with the structure shown.

[0062] It should be noted that, similar to the first embodiment, this embodiment can also... Figure 6 The joining process in (d) and Figure 6 An annealing process is performed between the sheet metal processing steps in (f) to heat the joint to a specified temperature.

[0063] (Third Implementation)

[0064] Figure 7 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the third embodiment of the present invention. In this embodiment, Figure 7 The functional substrate 1b of the composite substrate 120 shown in (a) has: an InP layer 10 composed of InP crystals, an epitaxial layer 50, and an oxide film 60. Additionally, Figure 7 The composite substrate 121 shown in (b) is from Figure 7 The composite substrate 120 in (a) is formed by removing the InP layer 10.

[0065] Epitaxial layer 50 is a layer composed of crystals of various materials (such as InP, BeZnSeTe, BeZnCdSe, MgZnCdSe, InGaAsP, InGaAlAs, InGaAs, InAs, AlAsSb, InAlAs, etc., hereinafter referred to as "epitaxy materials") that can be formed on InP layer 10 by epitaxial growth. Epitaxial layer 50 is formed by epitaxially growing a layer composed of crystals of these materials on InP layer 10. It should be noted that multiple epitaxial materials can be mixed in epitaxial layer 50.

[0066] The oxide film 60 is an oxide layer formed on the surface of the epitaxial layer 50 by natural oxidation of a portion of the epitaxial material constituting the epitaxial layer 50 in air before the functional substrate 1b is bonded to the support substrate 30, and is disposed between the epitaxial layer 50 and the support substrate 30.

[0067] The composite substrate 120 in this embodiment is similar to that described in the first embodiment. Figure 2 (a) in Figure 3 The process is the same as that in step (f). That is, a functional substrate 1b having a specified thickness of InP layer 10, epitaxial layer 50 and oxide film 60 is prepared, and the functional substrate 1b is subjected to... Figure 2 In step (b), the oxide film removal and activation process removes a portion of the oxide film 60, thinning it, and activates the surfaces of the functional substrate 1b and the semiconductor substrate 30A. Afterwards, the process is carried out... Figure 2 The sputtering process in (c) and Figure 3 The bonding process in step (d) forms a bond between the functional substrate 1b and the support substrate 30, and the bonding process is performed on the bond. Figure 3 The thin plate processing step (f) in the middle, thereby manufacturing the thin plate Figure 7 The composite substrate 120 with the structure shown in (a) is shown in the figure.

[0068] In the composite substrate 120, the functional substrate 1b has: a first functional layer 51 formed of an InP layer 10 composed of InP crystals, and a second functional layer 52 and a third functional layer 53 formed within the epitaxial layer 50. The second functional layer 52 is mainly composed of crystalline epitaxial material, and the third functional layer 53 is mainly composed of amorphous epitaxial material. It should be noted that the third functional layer 53 is a layer containing rare gas atoms such as Ar irradiated in the form of FAB during the oxide film removal and activation process, and is configured to be closer to the support substrate 30 than the second functional layer 52.

[0069] Furthermore, in the composite substrate 120, a bonding interface 40, a first support layer 31, a second support layer 32, and a bonding layer 33 are formed within the support substrate 30, similar to the composite substrates 100 and 110 described in the first and second embodiments, respectively. These are formed in the bonded body obtained by the aforementioned bonding process.

[0070] Furthermore, the InP layer 10 is removed from the composite substrate 120, thereby manufacturing a Figure 7 The composite substrate 121 with the structure shown in (b) is an example of a composite substrate 121. For instance, the InP layer 10 can be removed using wet etching. In this composite substrate 121, the functional substrate 1b has a second functional layer 52 and a third functional layer 53 formed within the epitaxial layer 50. The second functional layer 52 is primarily composed of crystalline epitaxial material, and the third functional layer 53 is primarily composed of amorphous epitaxial material. The structure of the support substrate 30 is the same as that of the composite substrate 120.

[0071] (Fourth Implementation)

[0072] Figure 8 This is a schematic cross-sectional view showing the general structure of the composite substrate according to the fourth embodiment of the present invention. In this embodiment, Figure 8 The composite substrate 130 shown in (a) is relative to the one described in the third embodiment. Figure 7 The composite substrate 120 in (a) has a structure in which an oxide film 60 is not disposed between the epitaxial layer 50 and the support substrate 30. That is, the composite substrate 130 has a functional substrate 1c composed of an InP layer 10 and an epitaxial layer 50 but without an oxide film 60, replacing the functional substrate 1b in the composite substrate 120. Furthermore, Figure 8 The composite substrate 131 shown in (b) is from Figure 8 The composite substrate 130 in (a) is formed by removing the InP layer 10.

[0073] The composite substrate 130 in this embodiment is similar to that described in the second embodiment. Figure 5 (a) in Figure 6 The process is the same as that in step (f). That is, a functional substrate 1b having a specified thickness of InP layer 10, epitaxial layer 50 and oxide film 60 is prepared, and the functional substrate 1b is subjected to... Figure 5 In step (b), the oxide film removal and activation process completely removes the oxide film 60 to form the functional substrate 1c, and activates the surfaces of the functional substrate 1c and the semiconductor substrate 30A. Afterwards, the process is carried out... Figure 5 The sputtering process in (c) and Figure 6 The bonding process in step (d) forms a bond between the functional substrate 1c and the support substrate 30, and the bond is then subjected to... Figure 6The thin plate processing step (f) in the middle, thereby manufacturing the thin plate Figure 8 The composite substrate 130 with the structure shown in (a) is shown in the figure.

[0074] It should be noted that, similarly to the composite substrate 120 described in the third embodiment, the functional substrate 1c in the composite substrate 130 of this embodiment also has a first functional layer 51 formed of an InP layer 10 composed of InP crystals, and a second functional layer 52 and a third functional layer 53 formed within the epitaxial layer 50. Furthermore, a bonding interface 40, a first support layer 31, a second support layer 32, and a bonding layer 33 are formed within the support substrate 30.

[0075] Furthermore, the InP layer 10 is removed from the composite substrate 130, thereby manufacturing a Figure 8 The composite substrate 131 with the structure shown in (b) is similar to the third embodiment. For example, the InP layer 10 can be removed by wet etching. In this composite substrate 131, the functional substrate 1c has a second functional layer 52 and a third functional layer 53 formed within the epitaxial layer 50. The second functional layer 52 is mainly composed of crystalline epitaxial material, and the third functional layer 53 is mainly composed of amorphous epitaxial material. The structure of the support substrate 30 is the same as that of the composite substrate 130.

[0076] Example

[0077] The following describes in detail embodiments used to verify the structure of the composite substrate involved in the present invention. It should be noted that, unless otherwise explicitly stated, the following sequence is performed at room temperature.

[0078] (Example 1)

[0079] According to reference Figure 2 and Figure 3 The manufacturing process described herein involves fabricating a bond. Specifically, InP wafers and SiC wafers of specified dimensions are prepared, with the InP wafer used as a functional substrate 1 and the SiC wafer used as a semiconductor substrate 30A.

[0080] Furthermore, after cleaning the surfaces of the functional substrate 1 and the semiconductor substrate 30A respectively, the functional substrate 1 and the semiconductor substrate 30A are arranged in a vacuum chamber with FAB guns positioned vertically, such that the substrates are located within the irradiation range of each FAB gun and their surfaces face each other. The vacuum chamber is then evacuated to 10°C. -6At approximately 100 Pa, FAB (accelerating voltage 0.9 kV, current 100 mA) using Ar gas was simultaneously irradiated from each FAB gun toward the surfaces of the functional substrate 1 and the semiconductor substrate 30A for 1.5 seconds. As a result, a portion of the oxide film 20 formed on the surface of the functional substrate 1 was removed, resulting in a film thinner than its original thickness.

[0081] Then, the FAB irradiation on the functional substrate 1 side is stopped, while the FAB irradiation on the semiconductor substrate 30A side is continued for another 180 seconds (totaling 181.5 seconds). It should be noted that, at this time, in order to ensure that the internal pressure of the vacuum chamber does not change before and after the irradiation on the functional substrate 1 side is stopped, Ar gas is continuously supplied to the FAB gun on the functional substrate 1 side, thus stopping the FAB irradiation from the FAB gun toward the surface of the functional substrate 1. As a result, a sputtered film 30B is formed on the surface of the functional substrate 1 (oxide film 20).

[0082] Next, the functional substrate 1 with the sputtered film 30B and the semiconductor substrate 30A are directly bonded. Specifically, the irradiated surfaces of the two substrates are overlapped, and the two substrates are bonded at room temperature under a pressure of 10000N for 2 minutes to obtain a bonded body. Thus, a... Figure 1 The composite substrate 100 with the structure shown.

[0083] (Example 2)

[0084] According to reference Figure 2 and Figure 3 The manufacturing process described herein involves a longer FAB irradiation time for the functional substrate 1 than in Example 1, to fabricate a bond. Specifically, the functional substrate 1 and the semiconductor substrate 30A, identical to those in Example 1, are respectively placed in a vacuum chamber, and the vacuum chamber is evacuated to 10°C. -6 At approximately 6.5 Pa, FAB using Ar gas was simultaneously irradiated from each FAB gun toward the surfaces of the functional substrate 1 and the semiconductor substrate 30A under the same conditions as in Example 1. As a result, a portion of the oxide film 20 formed on the surface of the functional substrate 1 was removed, resulting in a film thinner than its original thickness and further thinning compared to Example 1.

[0085] Then, the FAB irradiation on the functional substrate 1 side is stopped, while the FAB irradiation on the semiconductor substrate 30A side is continued for another 180 seconds (totaling 186.5 seconds). It should be noted that, similar to Example 1, to ensure that the internal pressure of the vacuum chamber does not change before and after the irradiation on the functional substrate 1 side is stopped, Ar gas is continuously supplied to the FAB gun on the functional substrate 1 side, and the FAB irradiation from the FAB gun toward the surface of the functional substrate 1 is stopped. As a result, a sputtered film 30B is formed on the surface of the functional substrate 1 (oxide film 20).

[0086] Next, similarly to Example 1, the functional substrate 1 on which the sputtered film 30B is formed and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 1 The composite substrate 100 with the structure shown.

[0087] (Example 3)

[0088] According to reference Figure 2 and Figure 3 The manufacturing process described herein involves a longer FAB irradiation time for the functional substrate 1 than in Examples 1 and 2, to fabricate a bond. Specifically, the functional substrate 1 and the semiconductor substrate 30A, identical to those in Example 1, are respectively placed in a vacuum chamber, and the vacuum chamber is evacuated to 10°C. -6 At approximately 10.5 Pa, FAB 1 using Ar gas was simultaneously irradiated from each FAB gun toward the surfaces of the functional substrate 1 and the semiconductor substrate 30A under the same conditions as in Example 1. As a result, a portion of the oxide film 20 formed on the surface of the functional substrate 1 was removed, resulting in a film thinner than its original thickness and further thinner than in Example 2.

[0089] Then, the FAB irradiation on the functional substrate 1 side is stopped, while the FAB irradiation on the semiconductor substrate 30A side is continued for another 180 seconds (totaling 190.5 seconds). It should be noted that, similar to Examples 1 and 2, to ensure that the internal pressure of the vacuum chamber does not change before and after the irradiation on the functional substrate 1 side is stopped, Ar gas is continuously supplied to the FAB gun on the functional substrate 1 side, thus stopping the FAB irradiation from the FAB gun towards the surface of the functional substrate 1. As a result, a sputtered film 30B is formed on the surface of the functional substrate 1 (oxide film 20).

[0090] Next, similarly to Examples 1 and 2, the functional substrate 1 with the sputtered film 30B formed thereon and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 1 The composite substrate 100 with the structure shown.

[0091] (Example 4)

[0092] According to reference Figure 5 and Figure 6 The manufacturing process described herein involves fabricating a bond. Specifically, the functional substrate 1 and the semiconductor substrate 30A, identical to those in Example 1, are respectively disposed within a vacuum chamber, and the vacuum chamber is evacuated to 10 °C. - 6 At approximately 100 Pa, the surfaces of the functional substrate 1 and the semiconductor substrate 30A were simultaneously irradiated with FAB using Ar gas for 14.5 seconds from each FAB gun toward the surface of the functional substrate 1 and the semiconductor substrate 30A, under the same conditions as in Example 1. As a result, the oxide film 20 formed on the surface of the functional substrate 1 was completely removed, and a functional substrate 1a with only an InP layer 10 and no oxide film 20 was formed.

[0093] Then, the FAB irradiation on the functional substrate 1a side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for another 180 seconds (totaling 194.5 seconds). It should be noted that, similar to Examples 1-3, to ensure that the internal pressure of the vacuum chamber did not change before and after the irradiation on the functional substrate 1a side was stopped, Ar gas was continued to be supplied to the FAB gun on the functional substrate 1a side, and the FAB irradiation from the FAB gun towards the surface of the functional substrate 1a was stopped. As a result, a sputtered film 30B was formed on the surface of the functional substrate 1a.

[0094] Next, similarly to Examples 1-3, the functional substrate 1a with the sputtered film 30B formed thereon and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 4 The composite substrate 110 with the structure shown.

[0095] (Example 5)

[0096] According to reference Figure 5 and Figure 6 The manufacturing process described herein involves a longer FAB irradiation time for the functional substrate 1 than in Example 4, to fabricate a bond. Specifically, the functional substrate 1 and the semiconductor substrate 30A, identical to those in Example 1, are respectively placed in a vacuum chamber, and the vacuum chamber is evacuated to 10°C. -6 At a state of approximately Pa, the FAB guns were used to simultaneously irradiate the surfaces of the functional substrate 1 and the semiconductor substrate 30A with Ar gas for 18.5 seconds, under the same conditions as in Example 1. As a result, the oxide film 20 formed on the surface of the functional substrate 1 was completely removed, and a functional substrate 1a with only an InP layer 10 and no oxide film 20 was formed.

[0097] Then, the FAB irradiation on the functional substrate 1a side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for another 180 seconds (totaling 198.5 seconds). It should be noted that, similar to Examples 1-4, to ensure that the internal pressure of the vacuum chamber did not change before and after the irradiation on the functional substrate 1a side was stopped, Ar gas was continued to be supplied to the FAB gun on the functional substrate 1a side, and the FAB irradiation from the FAB gun towards the surface of the functional substrate 1a was stopped. As a result, a sputtered film 30B was formed on the surface of the functional substrate 1a.

[0098] Next, similarly to Examples 1-4, the functional substrate 1a with the sputtered film 30B formed thereon and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 4 The composite substrate 110 with the structure shown.

[0099] It should be noted that in the above embodiments 1 to 5, after a predetermined period of FAB irradiation from the FAB gun toward the functional substrates 1 and 1a and the semiconductor substrate 30A, the FAB irradiation on the functional substrates 1 and 1a side is stopped first. This allows time required for the formation of the sputtered film 30B to be used for cooling the functional substrates 1 and 1a, thus reducing the impact of warpage in the bonded composite substrates 100 and 110. In particular, when the functional substrates 1 and 1a have a larger coefficient of thermal expansion than the semiconductor substrate 30A, stopping the FAB irradiation on the functional substrates 1 and 1a side first yields a greater effect in reducing warpage after bonding.

[0100] (Comparative Example 1)

[0101] To confirm the effectiveness of the present invention, as Comparative Example 1, the same functional substrate 1 and semiconductor substrate 30A as in Examples 1-5 were respectively disposed in a vacuum chamber, and the vacuum chamber was evacuated to 10°C. -6 At approximately 180 Pa, FAB irradiation was performed only on the semiconductor substrate 30A side, without irradiating the functional substrate 1 side. The FAB irradiation conditions on the semiconductor substrate 30A side were the same as in Examples 1-5. As a result, a sputtered film 30B was formed on the surface of the functional substrate 1.

[0102] Next, similarly to Examples 1-5, the functional substrate 1 on which the sputtered film 30B is formed and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 1 The composite substrate 100 with the structure shown.

[0103] (Comparative Example 2)

[0104] Furthermore, as a comparative example 2, the same functional substrate 1 and semiconductor substrate 30A as in Examples 1-5 were respectively disposed in the vacuum chamber, and the vacuum chamber was evacuated to 10. -6 At approximately Pa, both the functional substrate 1 and the semiconductor substrate 30A were subjected to FAB irradiation for 24.5 seconds. Afterward, the FAB irradiation on the functional substrate 1 side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for an additional 180 seconds (totaling 204.5 seconds). The FAB irradiation conditions on the semiconductor substrate 30A side were the same as in Examples 1-5. As a result, the oxide film 20 formed on the surface of the functional substrate 1 was completely removed, forming a functional substrate 1a with only an InP layer 10 and no oxide film 20. Furthermore, a sputtered film 30B was formed on the surface of the functional substrate 1a.

[0105] Next, similarly to Examples 1-5, the functional substrate 1a with the sputtered film 30B formed thereon and the semiconductor substrate 30A are directly bonded together, thereby obtaining... Figure 4 The composite substrate 110 shown is an example of this Comparative Example 2. In the composite substrate 110, during the thin-plate processing step, the bonding interface 40 peeled off. This is believed to be because the FAB irradiation time on the semiconductor substrate 30A side was too long, which increased the surface roughness of the bonding interface 40 and led to a decrease in bonding strength.

[0106] (Confirmation of the layered structure)

[0107] Transmission electron microscopy (TEM) was performed on the cross sections of composite substrates 100 and 110 fabricated in Examples 1-5 and Comparative Example 1, including the bonding interface 40, to confirm the stacked structure of composite substrates 100 and 110. Figure 9 (a) shows an observation photograph of Comparative Example 1. Figure 9 (b) shows an observation photograph of Example 1. Figure 9 (c) shows an observation photograph of Example 2. Figure 9 (d) shows an observation photograph of Example 3. Figure 9 (e) shows an observation photograph of Example 4. Figure 9 (f) shows an observation photograph of Example 5. It should be noted that... Figure 9 (a) in Figure 9 Comparative Example 1 and Examples 1-3 shown in (d) belong to composite substrates 100 with oxide film 20 after bonding of functional substrate 1. Figure 9 (e) Figure 9 Examples 4 and 5 shown in (f) belong to composite substrates 110 in which the functional substrate 1a after bonding does not have an oxide film 20.

[0108] Depend on Figure 9 (b) Figure 9 (c) Figure 9 As shown in the observation photographs of Examples 1 to 3 (d), two layers are formed inside the InP layer 10 in the functional substrate 1. These layers are sequentially designated as a first functional layer 11 and a second functional layer 12, starting from the side away from the support substrate 30. Additionally, three layers are formed inside the support substrate 30. These layers are sequentially designated as a first support layer 31, a second support layer 32, and a bonding layer 33, starting from the side away from the functional substrate 1. The bonding layer 33 is in contact with the oxide film 20 of the functional substrate 1, and a bonding interface 40 formed in the aforementioned bonding process exists between the second support layer 32 and the bonding layer 33. That is, in the bonding process, the surface of the second support layer 32 in the semiconductor substrate 30A before bonding and the surface of the sputtered film 30B formed on the oxide film 20 in the functional substrate 1 before bonding are bonded to each other, thereby making the sputtered film 30B a bonding layer 33, forming a bond between the functional substrate 1 and the support substrate 30 with the bonding interface 40 inside the support substrate 30.

[0109] Similarly, by Figure 9 (e) Figure 9 The observation photographs of embodiments 4 and 5 shown in (f) also show that: a first functional layer 11 and a second functional layer 12 are formed inside the functional substrate 1a (InP layer 10), a first support layer 31, a second support layer 32 and a bonding layer 33 are formed inside the support substrate 30, and a bonding interface 40 exists between the second support layer 32 and the bonding layer 33.

[0110] In addition, by Figure 9 (b) ~ Figure 9 As can be seen from the observation photograph (f) in the figure, the second functional layer 12 does not have a crystalline structure compared to the first functional layer 11, which is composed of InP crystals, and is composed of InP amorphous material. That is, it can be seen that in Examples 1 to 5, the second functional layer 12 in the functional substrates 1 and 1a before bonding, corresponding to the portion of the surface of the functional substrate 1 and 1a irradiated with FAB to a predetermined depth during the oxide film removal and activation process, is formed as an amorphized layer of InP, which is the material of the functional substrates 1 and 1a.

[0111] Similarly, by Figure 9 (b) ~ Figure 9As can be seen from the observation photograph (f) in the figure, the second support layer 32 and the bonding layer 33 do not have a crystalline structure compared to the first support layer 31, which is composed of SiC crystals, and are composed of SiC amorphous material. That is, it can be seen that in Examples 1 to 5, the second support layer 32, which corresponds to the portion of the surface of the semiconductor substrate 30A irradiated with FAB to a predetermined depth in the oxide film removal and activation process and the sputtering process, and the bonding layer 33, which corresponds to the sputtered film 30B formed on the surface of the functional substrates 1 and 1a in the sputtering process, are respectively formed as SiC amorphized layers that serve as the material of the support substrate 30.

[0112] on the other hand, Figure 9 In the observation photograph of Comparative Example 1 shown in (a), the InP layer 10 in the functional substrate 1 is composed only of a first functional layer 11 having a crystalline structure, and a second functional layer 12 as in Examples 1 to 5 is not formed in the InP layer 10. That is, it can be seen that in Comparative Example 1, since the oxide film removal and activation process was not performed on the functional substrate 1 before bonding, a second functional layer 12 composed of an amorphous InP film was not formed.

[0113] (Thickness of oxide film)

[0114] Regarding the composite substrates 100 fabricated in Examples 1-3 respectively, according to Figure 9 (b) Figure 9 (c) Figure 9 The thickness of the oxide film 20 was measured in the observation photograph (d) in Example 1. The results showed that the thickness was 0.9 nm in Example 1 and 0.6 nm in Examples 2 and 3. On the other hand, in Comparative Example 1, according to... Figure 9 In the observation photograph (a) above, the thickness of the oxide film 20 was measured and found to be 1 nm. That is, it can be seen that in Examples 1-3, during the oxide film removal and activation process, a portion of the oxide film 20 was removed by FAB irradiation, resulting in a thickness less than the original oxide film 20. It should be noted that in Examples 4 and 5, the oxide film 20 was completely removed during the oxide film removal and activation process; therefore, the thickness of the oxide film 20 was 0.

[0115] (Thickness of the bonding layer)

[0116] Regarding the composite substrates 100 and 110 fabricated in Comparative Example 1 and Examples 1-5 respectively, according to Figure 9 (a) in Figure 9 The thickness of the bonding layer 33 was measured in the observation photograph (d) in the example. The results showed that the thickness was 0.4 nm in Comparative Example 1, 0.8 nm in Example 1, 0.6 nm in Examples 2-4, and 0.7 nm in Example 5.

[0117] In Comparative Examples 1 and Examples 1-5, the FAB irradiation time for the semiconductor substrate 30A side in the sputtering process after the FAB irradiation on the functional substrates 1 and 1a side has stopped is 180 seconds. As described above, the bonding layer 33 is a portion equivalent to the sputtered film 30B formed on the functional substrates 1 and 1a side before bonding in the sputtering process. Therefore, it is assumed that the thickness of the bonding layer 33 is determined by the FAB irradiation time for the semiconductor substrate 30A side. Therefore, considering measurement errors, the actual thickness of the bonding layer 33 in Comparative Examples 1 and 2 and Examples 1-5 is approximately equal, and is considered to be around 0.6 nm.

[0118] (Ar peak distance)

[0119] EDX analysis was performed on the cross-sections of composite substrates 100 and 110, including the bonding interface 40, fabricated in Examples 1-5 and Comparative Example 2, respectively, to perform structural analysis of composite substrates 100 and 110. The results showed that the content of Ar, an element used as a rare gas for FAB irradiation, had a peak in the second functional layer 12 on the side of the functional substrates 1 and 1a, and a peak in the second support layer 32 on the side of the support substrate 30. The distance between these peaks was 2.2 nm in Example 1, 2.8 nm in Example 2, 3.2 nm in Example 3, 3.5 nm in Example 4, 4.0 nm in Example 5, and 4.6 nm in Comparative Example 2.

[0120] It should be noted that in the composite substrate 100 fabricated in Comparative Example 1, FAB irradiation was not performed on the functional substrate 1 side. Therefore, the content of Ar, an element of rare gas used for FAB irradiation, only has a peak in the second support layer 32 on the support substrate 30 side, and no peak exists on the functional substrate 1 side.

[0121] Figure 10 This table summarizes the FAB irradiation time, presence or absence of peeling at the bonding interface 40 during processing, thickness of the oxide film 20, and distance between Ar peaks in Examples 1-5 and Comparative Examples 1 and 2. Figure 10 As can be seen from the table, the longer the FAB irradiation time is for functional substrates 1 and 1a, the greater the distance between Ar peaks.

[0122] (Relationship between FAB irradiation time and Ar peak distance)

[0123] Figure 11 This is a graph showing the relationship between FAB irradiation time and Ar peak distance for functional substrates 1 and 1a when the support substrate 30 is made of SiC. Figure 11In the diagram, the horizontal axis represents the FAB irradiation time for functional substrates 1 and 1a, and the vertical axis represents the Ar peak-to-peak distance. Additionally, the plotting points 71a to 71f, indicated by black circles, represent combinations of FAB irradiation time and Ar peak-to-peak distance values ​​obtained in each embodiment and comparative example. Specifically, plotting point 71a represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Embodiment 1; plotting point 71b represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Embodiment 2; plotting point 71c represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Embodiment 3; plotting point 71d represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Embodiment 4; plotting point 71e represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Embodiment 5; and plotting point 71f represents the combination of FAB irradiation time and Ar peak-to-peak distance values ​​in Comparative Example 2. As described above, in Comparative Example 1, there are no peaks on the functional substrate 1 side; therefore… Figure 11 In Comparative Example 1, no corresponding drawing point exists in the drawing objects.

[0124] If linear interpolation is performed on plotting points 71a to 71f, a straight line 71 is obtained. This straight line 71 represents the relationship between the FAB irradiation time and the distance between Ar peaks for functional substrates 1 and 1a when the thickness of the bonding layer 33 is 0.6 nm.

[0125] As described above, the thickness of the bonding layer 33 is determined by the FAB irradiation time on the semiconductor substrate 30A side during the sputtering process, and the Ar peak spacing also varies depending on the thickness of the bonding layer 33. That is, it is assumed that if the thickness of the bonding layer 33 increases or decreases, the Ar peak spacing also increases or decreases accordingly. Furthermore, in the composite substrates 100 and 110, the greater the thickness of the bonding layer 33, the higher the bonding strength between the functional substrates 1 and 1a and the support substrate 30. On the other hand, considering thermal conductivity, light propagation, etc., the thickness of the bonding layer 33 is preferably as small as possible. Based on these conditions, when the support substrate 30 is made of SiC, the thickness of the bonding layer 33 in the composite substrates 100 and 110 is preferably in the range of about 0.6 nm to 2.7 nm.

[0126] Figure 11 In the graph, plotting points 72a to 72f, represented by white circles, represent combinations of FAB irradiation time and Ar inter-peak distance values ​​when plotting points 71a to 71f are slid along the vertical axis of the graph by increasing the Ar inter-peak distance value by 2.1 nm. Linear interpolation of these plotting points 72a to 72f yields line 72. This line 72 represents the relationship between FAB irradiation time and Ar inter-peak distance for functional substrates 1 and 1a when the thickness of the bonding layer 33 is 0.6 + 2.1 = 2.7 nm.

[0127] exist Figure 11In the diagram shown, range 73, enclosed by plotting points 71a, 71b, 71c, 72a, 72b, and 72c, represents, for example, the range of combinations of FAB irradiation time and Ar peak distance values ​​that can be obtained when the composite substrate 100, processed by FAB irradiation in the oxide film removal and activation process as in Examples 1-3, is thinner than the original thickness. Additionally, range 74, enclosed by plotting points 71d, 71e, 72d, and 72e, represents, for example, the range of combinations of FAB irradiation time and Ar peak distance values ​​that can be obtained when the composite substrate 110, after the oxide film 20 has been completely removed by FAB irradiation in the oxide film removal and activation process as in Examples 4 and 5, maintains bonding strength. It should be noted that the range between ranges 73 and 74 corresponds to either the composite substrate 100 or the composite substrate 110.

[0128] As explained above, when the support substrate 30 is made of SiC, in the composite substrates 100 and 110 of the first and second embodiments of the present invention represented by Examples 1 to 5, the combination of FAB irradiation time and Ar peak distance values ​​includes any one of the ranges 73 and 74 and the range therebetween. That is, in the composite substrates 100 and 110 of the first and second embodiments, the Ar peak distance values ​​in the second functional layer 12 on the side of the functional substrate 1 and 1a and the second support layer 32 on the side of the support substrate 30 are in the range of plotting point 71a to plotting point 72e, specifically 2.2 nm or more and 6.1 nm or less. Therefore, when the semiconductor material used in the support substrate 30 is SiC, the Ar peak distance is preferably 2.2 nm or more and 6.1 nm or less.

[0129] It should be explained that Figure 11 The diagram shows a combination of FAB irradiation time and Ar peak distance values ​​when the support substrate 30 is made of SiC. However, the same relationship applies when the support substrate 30 is made of other semiconductor materials, such as Si. In SiC and Si, the depth to which Ar penetrates into the support substrate 30 during FAB irradiation differs; therefore, the Ar peak distance values ​​for each FAB irradiation time need to be corrected to account for this difference in depth.

[0130] Figure 12 This is a graph showing the relationship between FAB irradiation time and Ar peak distance for functional substrates 1 and 1a when the support substrate 30 is made of Si. Figure 12 In, with Figure 11Similarly, the horizontal axis represents the FAB irradiation time for functional substrates 1 and 1a, and the vertical axis represents the Ar peak distance. Additionally, the plotting points 81a to 81f, indicated by black circles, represent combinations of FAB irradiation time and Ar peak distance values ​​calculated based on the combinations of FAB irradiation time and Ar peak distance values ​​obtained in the aforementioned embodiments and comparative examples, respectively, when the support substrate 30 is Si. These plotting points 81a to 81f and... Figure 11 The plotting points 71a to 71f correspond to these values. Similarly, the plotting points 82a to 82f, represented by white circles, also represent combinations of FAB irradiation time and Ar peak-to-peak distance values ​​when the supporting substrate 30 is Si. These plotting points 82a to 82f are related to... Figure 11 The drawing points 72a to 72f correspond to respectively.

[0131] When the support substrate 30 is Si, according to the aforementioned conditions, the thickness of the bonding layer 33 in the composite substrates 100 and 110 is preferably in the range of about 0.3 nm to 3 nm. Figure 12 In the diagram, if linear interpolation is performed on plotting points 81a to 81f, straight line 81 is obtained. This straight line 81 represents the relationship between FAB irradiation time and Ar peak distance for functional substrates 1 and 1a when the thickness of the bonding layer 33 is 0.3 nm. Similarly, if linear interpolation is performed on plotting points 82a to 82f, straight line 82 is obtained. This straight line 82 represents the relationship between FAB irradiation time and Ar peak distance for functional substrates 1 and 1a when the thickness of the bonding layer 33 is 3 nm.

[0132] exist Figure 12 In the diagram shown, the area 83 enclosed by plotting points 81a, 81b, 81c, 82a, 82b, and 82c is... Figure 11 Similarly, range 73 represents the range of combinations of FAB irradiation time and Ar peak distance values ​​that can be obtained when processing the oxide film 20 into a composite substrate 100 thinner than the original thickness using FAB irradiation in the oxide film removal and activation process. Additionally, range 84, enclosed by plotting points 81d, 81e, 82d, and 82e, and... Figure 11 Range 83 similarly represents a range of combinations of FAB irradiation time and Ar peak distance values ​​that can maintain bonding strength and achieve a composite substrate 110 in which the oxide film 20 has been completely removed by FAB irradiation in the oxide film removal and activation process. It should be noted that the range between range 83 and range 84 corresponds to either composite substrate 100 or composite substrate 110.

[0133] As explained above, when the support substrate 30 is made of Si, in the composite substrates 100 and 110 according to the first and second embodiments of the present invention, the combination of FAB irradiation time and Ar peak distance values ​​includes any one of the ranges 83 and 84 and the range therebetween. That is, in the composite substrates 100 and 110 according to the first and second embodiments, the Ar peak distance values ​​in the second functional layer 12 on the side of the functional substrate 1 and 1a and the second support layer 32 on the side of the support substrate 30 are in the range from plotting point 81b to plotting point 82e, specifically 2.5 nm or more and 6.9 nm or less. Therefore, when the semiconductor material used in the support substrate 30 is Si, the Ar peak distance is preferably 2.5 nm or more and 6.9 nm or less.

[0134] It should be noted that, in the above description, the relationship between FAB irradiation time and Ar peak distance was explained for composite substrates 100 and 110 having functional substrates 1 and 1a made of InP crystals. However, as described in the third and fourth embodiments, the same relationship also applies to composite substrates 120, 121, 130, and 131 having functional substrates 1b and 1c having an epitaxial layer 50 made of epitaxial material formed on the InP layer 10. That is, Figure 11 , 12 The relationship between FAB irradiation time and Ar peak distance shown in the charts can also be applied to composite substrates 120, 121, 130, and 131, which are supported by SiC or Si.

[0135] According to the embodiments of the present invention described above, the following effects are achieved.

[0136] (1) The composite substrates 100-131 include: functional substrates 1, 1a, 1b, and 1c, which are configured to include at least one of InP and a material that can be formed by epitaxial growth on a crystal of InP; and a support substrate 30, which is made of a semiconductor material and is bonded to the functional substrates 1, 1a, 1b, and 1c to support the functional substrates 1, 1a, 1b, and 1c. The functional substrates 1, 1a, 1b, and 1c have a first layer (a first functional layer 11, or a first functional layer 51 and a second functional layer 52) and a second layer (a second functional layer 12 or a third functional layer 53), the second layer being disposed on the side closer to the support substrate 30 than the first layer, and being made of an amorphous material containing rare gas elements. The support substrate 30 includes: a first support layer 31; a second support layer 32 disposed closer to the functional substrates 1, 1a, 1b, and 1c than the first support layer 31, and composed of an amorphous body of a semiconductor material containing rare gas elements; and a bonding layer 33 in contact with the functional substrates 1, 1a, 1b, and 1c, and composed of an amorphous body of a semiconductor material. Therefore, based on the composite substrates 100 to 131 obtained by bonding the functional substrates 1, 1a, 1b, and 1c containing InP or a crystallized material that can be formed by epitaxial growth on a crystallized InP and the support substrate 30 via the bonding layer 33, composite substrates 100 to 131 that can efficiently dissipate the heat of the functional substrates 1, 1a, 1b, and 1c to the support substrate 30 side can be realized.

[0137] Furthermore, in the field of photonics, a technique has been developed to directly bond an SOI substrate, which includes an optical circuit made of Si, and an InP substrate, and fabricate devices such as semiconductor lasers using InP on this optical circuit to form an optical transceiver, thereby achieving device miniaturization. In photonic devices with such a structure, since light propagates at the bonding interface between the SOI substrate and the InP substrate, no other material is sandwiched at this interface, or even if some material is sandwiched, the energy loss of that material in the wavelength band in use is required to be low. Therefore, as with the composite substrate described in the aforementioned Patent Document 1, it is undesirable to have a barrier layer such as indium oxide at the bonding interface. In this regard, in composite substrates 100 to 131, the oxide film 20 is removed or its thickness is reduced, thus easily achieving the above requirements.

[0138] (2) In the composite substrates 100 and 110, the functional substrates 1 and 1a have: a first functional layer 11 made of InP crystals and a second functional layer 12 made of InP amorphous material. In this configuration, the first layer is the first functional layer 11 and the second layer is the second functional layer 12. Therefore, even if the functional substrates 1 and 1a made of InP crystals and the support substrate 30 are directly bonded, composite substrates 100 and 110 with sufficient bonding strength can be achieved.

[0139] (3) In the composite substrate 100, the functional substrate 1 has an InP oxide film 20 between the second layer (second functional layer 12) and the support substrate 30. Therefore, a composite substrate 100 can be realized in which the oxide film 20 formed by the natural oxidation of InP remains and the heat of the functional substrate 1 is efficiently dissipated to the support substrate 30 side.

[0140] (4) In the composite substrates 120 and 130, the functional substrates 1b and 1c have: a first functional layer 51 made of InP crystals, a second functional layer 52 made of a material crystal formed by epitaxial growth on the first functional layer 51, and a third functional layer 53 made of the amorphous form of the material. In this configuration, the first layer is the first functional layer 51 and the second functional layer 52, and the second layer is the third functional layer 53. Therefore, even if the functional substrates 1b and 1c having epitaxial layers 50 made of various epitaxial materials formed by epitaxial growth on the InP layer 10 made of InP crystals and the support substrate 30 are directly bonded, composite substrates 120 and 130 with sufficient bonding strength can be achieved.

[0141] (5) In the composite substrate 120, the functional substrate 1b has an oxide film 60 of epitaxial material between the second layer (third functional layer 53) and the support substrate 30. Therefore, a composite substrate 120 can be realized in which the oxide film 60 formed by the natural oxidation of the epitaxial material remains and the heat of the functional substrate 1b is efficiently dissipated to the support substrate 30 side.

[0142] (6) In the composite substrates 121 and 131, the functional substrates 1b and 1c have: a second functional layer 52 composed of a crystalline material that can be formed on a crystalline InP substrate by epitaxial growth, and a third functional layer 53 composed of an amorphous form of the same material. In this configuration, the first layer is the second functional layer 52, and the second layer is the third functional layer 53. Therefore, in the composite substrates 121 and 131 formed by removing the InP layer 10 from the composite substrates 120 and 130 respectively, sufficient bonding strength can also be obtained between the functional substrates 1b and 1c and the support substrate 30.

[0143] (7) In the composite substrate 121, the functional substrate 1b has an oxide film 60 of epitaxial material between the second layer (third functional layer 53) and the support substrate 30. Therefore, similar to the composite substrate 120, the oxide film 60 formed by the natural oxidation of the epitaxial material can remain and the heat of the functional substrate 1b can be efficiently dissipated to the support substrate 30 side.

[0144] (8) In the composite substrates 100, 120, and 121, the thickness of the oxide films 20 and 60 is preferably less than 1 nm. Accordingly, a portion of the oxide films 20 and 60 formed by natural oxidation in the functional substrates 1 and 1b before bonding can be removed to make them thinner, thereby improving the thermal conductivity from the functional substrates 1 and 1b toward the support substrate 30.

[0145] (9) In composite substrates 100-131, the content of Ar, a rare gas element, has peaks in the second layer (second functional layer 12 or third functional layer 53) and the second support layer 32, respectively. When the semiconductor material used in the support substrate 30 is SiC, the distance between these peaks is preferably 2.2 nm or more and 6.1 nm or less. In addition, when the semiconductor material used in the support substrate 30 is Si, the distance between these peaks is preferably 2.5 nm or more and 6.9 nm or less. Accordingly, composite substrates 100-131 that can sufficiently maintain the bonding strength and efficiently dissipate the heat of functional substrates 1, 1a, 1b, and 1c to the support substrate 30 side can be realized.

[0146] (10) A method for manufacturing composite substrates 100 and 110 comprising functional substrates 1 and 1a made of InP and a support substrate 30 made of semiconductor material supporting the functional substrates 1 and 1a includes the following steps: an oxide film removal and activation step, wherein FAB is irradiated onto the surface of the InP oxide film 20 formed on the surface of the functional substrate 1 and the surface of the semiconductor substrate 30A made of semiconductor material, respectively, to remove at least a portion of the oxide film 20, and to activate the surfaces of the functional substrates 1 and 1a and the semiconductor substrate 30A. Figure 2 (b) Figure 5 (b)); after the sputtering process, the oxide film removal and activation process is performed. After stopping the FAB irradiation on the surfaces of functional substrates 1 and 1a, the surface of semiconductor substrate 30A is irradiated with FAB, and semiconductor material is sputtered on the surfaces of functional substrates 1 and 1a. Figure 2 (c) Figure 5 (c)); and a bonding process, wherein functional substrates 1 and 1a, on which semiconductor material is sputtered by a sputtering process, and semiconductor substrate 30A are bonded to obtain a bond body ( Figure 3 (d) Figure 6(d)). Therefore, by integrating the semiconductor substrate 30A and the sputtered film 30B, a support substrate 30 can be formed, and composite substrates 100 and 110 can be fabricated.

[0147] (11) A method for manufacturing composite substrates 120 and 130 comprising functional substrates 1b and 1c having a material formed by epitaxial growth on a crystal of InP, and a support substrate 30 made of semiconductor material supporting the functional substrates 1b and 1c includes the following steps: an oxide film removal and activation step in which an oxide film 60 of epitaxial material formed on the surface of functional substrate 1b and a surface of semiconductor substrate 30A made of semiconductor material are irradiated with FAB to remove at least a portion of the oxide film 60 and to activate the surfaces of functional substrates 1b and 1c and semiconductor substrate 30A; a sputtering step in which, after the oxide film removal and activation step is performed, the surface of semiconductor substrate 30A is irradiated with FAB after the surface of functional substrates 1b and 1c is stopped, and semiconductor material is sputtered on the surface of functional substrates 1b and 1c; and a bonding step in which the functional substrates 1b and 1c sputtered with semiconductor material and semiconductor substrate 30A in the sputtering step are bonded to obtain a bonded body. Therefore, by integrating the semiconductor substrate 30A and the sputtered film 30B, a support substrate 30 can be formed, and composite substrates 120 and 130 can be manufactured.

[0148] It should be noted that in the embodiments of the present invention described above, during the oxide film removal and activation process, FAB irradiation is performed simultaneously from the first FAB gun toward the surface of the functional substrates 1 and 1b, and from the second FAB gun toward the surface of the semiconductor substrate 30A. This suppresses the adhesion of impurities such as oxide films formed on the surface of the semiconductor substrate 30A to the surfaces of the functional substrates 1, 1a, 1b, and 1c. However, the present invention is not limited to this. For example, a method can be used where FAB irradiation from the first FAB gun toward the functional substrates 1 and 1b is started first, followed by a predetermined delay before starting FAB irradiation from the second FAB gun toward the semiconductor substrate 30A, and then the FAB irradiation of the functional substrates 1, 1a, 1b, and 1c is stopped. Even so, the same effect as described above is obtained.

[0149] It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented using any constituent elements without departing from its spirit.

[0150] The above-described embodiments and modifications are merely examples, and are intended to be applied as long as they do not impair the features of the invention. The present invention is not limited to these embodiments. Furthermore, while the above description has illustrated various embodiments and modifications, the present invention is not limited to these. Other solutions conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0151] Explanation of reference numerals in the attached figures

[0152] 1, 1a, 1b, 1c: Functional substrates

[0153] 10: InP layer

[0154] 11: First functional layer

[0155] 12: Second functional layer

[0156] 20: Oxide film

[0157] 30: Support substrate

[0158] 30A: Semiconductor substrate

[0159] 30B: Sputtered film

[0160] 31: First Support Layer

[0161] 32: Second support layer

[0162] 33: Bonding layer

[0163] 40: Joint Interface

[0164] 50: Epitaxial layer

[0165] 51: First functional layer

[0166] 52: Second functional layer

[0167] 53: Third Functional Layer

[0168] 60: Oxide film

[0169] 100, 110, 120, 121, 130, 131: Composite substrates

Claims

1. A composite substrate comprising: A functional substrate, the functional substrate being configured as at least one of InP and a crystallization of a material that can be formed on a crystallization of InP by epitaxial growth; and A support substrate, made of semiconductor material, is bonded to the functional substrate to support it. The functional substrate has a first layer and a second layer, the second layer being disposed closer to the supporting substrate than the first layer, and is composed of an amorphous material containing rare gas elements. The supporting substrate has: a first supporting layer; a second supporting layer disposed on the side closer to the functional substrate than the first supporting layer, and composed of an amorphous body of the semiconductor material containing the rare gas element; and a bonding layer in contact with the functional substrate, and composed of an amorphous body of the semiconductor material.

2. The composite substrate according to claim 1, characterized in that, The functional substrate has: a first functional layer composed of InP crystals and a second functional layer composed of InP amorphous forms. The first layer is the first functional layer. The second layer is the second functional layer.

3. The composite substrate according to claim 2, characterized in that, The functional substrate has an InP oxide film between the second layer and the supporting substrate.

4. The composite substrate according to claim 1, characterized in that, The functional substrate has: a first functional layer composed of InP crystals, a second functional layer composed of crystals of the material formed by epitaxial growth on the first functional layer, and a third functional layer composed of the amorphous form of the material. The first layer consists of the first functional layer and the second functional layer. The second layer is the third functional layer.

5. The composite substrate according to claim 4, characterized in that, The functional substrate has an oxide film of the material between the second layer and the supporting substrate.

6. The composite substrate according to claim 1, characterized in that, The functional substrate has: a second functional layer composed of the crystalline form of the material, and a third functional layer composed of the amorphous form of the material. The first layer is the second functional layer. The second layer is the third functional layer.

7. The composite substrate according to claim 6, characterized in that, The functional substrate has an oxide film of the material between the second layer and the supporting substrate.

8. The composite substrate according to claim 3, 5 or 7, characterized in that, The thickness of the oxide film is less than 1 nm.

9. The composite substrate according to any one of claims 1 to 7, characterized in that, The content of the rare gas element has peaks in the second layer and the second support layer, respectively.

10. The composite substrate according to claim 9, characterized in that, The semiconductor material is SiC. The distance between the peak in the second layer and the peak in the second support layer is greater than 2.2 nm and less than 6.1 nm.

11. The composite substrate according to claim 9, characterized in that, The semiconductor material is Si. The distance between the peak in the second layer and the peak in the second support layer is greater than 2.5 nm and less than 6.9 nm.

12. A method for manufacturing a composite substrate, the composite substrate comprising: A functional substrate made of InP and a support substrate made of semiconductor material that supports the functional substrate. The method for manufacturing the composite substrate is characterized by comprising the following steps: The oxide film removal and activation process involves irradiating the InP oxide film formed on the surface of the functional substrate and the surface of the semiconductor substrate made of the semiconductor material with a high-speed atomic beam to remove at least a portion of the oxide film and activate the surfaces of the functional substrate and the semiconductor substrate. The sputtering process is followed by the oxide film removal and activation process. After stopping the irradiation of the surface of the functional substrate with the high-speed atomic beam, the surface of the semiconductor substrate is irradiated with the high-speed atomic beam again, and the semiconductor material is sputtered on the surface of the functional substrate. as well as The bonding process involves bonding the functional substrate on which the semiconductor material has been sputtered using the sputtering process with the semiconductor substrate to obtain a bonded body.

13. A method for manufacturing a composite substrate, the composite substrate comprising: The invention comprises a functional substrate formed by epitaxial growth on InP crystals and a support substrate made of semiconductor material that supports the functional substrate. The method for manufacturing the composite substrate is characterized by comprising the following steps: The oxide film removal and activation process involves irradiating the oxide film of the material formed on the surface of the functional substrate and the surface of the semiconductor substrate made of the semiconductor material with a high-speed atomic beam to remove at least a portion of the oxide film and to activate the surfaces of the functional substrate and the semiconductor substrate. The sputtering process is followed by the oxide film removal and activation process. After stopping the irradiation of the surface of the functional substrate with the high-speed atomic beam, the surface of the semiconductor substrate is irradiated with the high-speed atomic beam again, and the semiconductor material is sputtered on the surface of the functional substrate. as well as The bonding process involves bonding the functional substrate on which the semiconductor material has been sputtered using the sputtering process with the semiconductor substrate to obtain a bonded body.

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