Composite substrate, and manufacturing method for composite substrate

Abstract

This composite substrate includes: a functional substrate made of a functional material; and a support substrate made of a semiconductor material and bonded to the functional substrate to support the functional substrate. The functional substrate includes a first layer, and a second layer disposed closer to the support substrate than the first layer, and made of an amorphous body containing a rare gas. The support substrate includes: a first support layer; a second support layer disposed closer to the functional substrate than the first support layer, and made of an amorphous body of the semiconductor material containing the rare gas; and a bonding layer in contact with the functional substrate, and made of an amorphous body of the semiconductor material.

Description

Composite substrate and method for manufacturing the composite substrate

[0001] The present invention relates to a composite substrate and a method for manufacturing the same.

[0002] Conventionally, LN (LiNbO ３ : lithium niobate) and LT (LiTaO ３ Composite substrates are known that are formed by bonding a functional substrate made of a piezoelectric material such as lithium tantalate (LTC) to a support substrate made of a semiconductor material such as silicon, and are used in applications such as surface acoustic wave devices. One known method for fabricating such composite substrates involves irradiating the bonding surfaces of the functional substrate and the support substrate with a fast atom beam (FAB) to perform an activation process, and then directly bonding these bonding surfaces together. However, this method suffers from the problem of low bonding strength between the substrates, which can lead to separation during processing after bonding.

[0003] To solve the above problem, the technology disclosed in Patent Document 1 is known. Patent Document 1 describes a method for manufacturing a composite substrate by irradiating a support substrate with a fast atomic beam to sputter the semiconductor material of the support substrate, thereby forming a bonding layer made of an amorphous semiconductor material on the piezoelectric substrate by amorphizing the semiconductor material, and then pressure-bonding the piezoelectric substrate and support substrate together via this bonding layer. This method improves the bonding strength between the piezoelectric substrate and support substrate and prevents peeling after bonding.

[0004] Japanese Patent No. 7152711

[0005] In a composite substrate in which a functional substrate such as a piezoelectric substrate and a support substrate are bonded, it is preferable to shorten the sputtering time as much as possible from the viewpoint of productivity, and shortening the sputtering time results in a thinner bonding layer. On the other hand, in order to obtain a desired bonding strength in a conventional bonding method such as that disclosed in Patent Document 1, a certain thickness of the bonding layer is required.

[0006] The present invention has been made in consideration of the above, and its main object is to provide a composite substrate in which a functional substrate and a support substrate are bonded via a bonding layer, and a method for manufacturing the same, which can obtain sufficient bonding strength even if the bonding layer is thin.

[0007] The composite substrate according to the present invention comprises a functional substrate made of a functional material, and a support substrate made of a semiconductor material and bonded to the functional substrate to support the functional substrate, wherein the functional substrate comprises a first layer and a second layer made of an amorphous body containing a rare gas and arranged closer to the support substrate than the first layer, and the support substrate comprises a first support layer, a second support layer made of an amorphous body of the semiconductor material containing the rare gas and arranged closer to the functional substrate than the first support layer, and a bonding layer in contact with the functional substrate and made of an amorphous body of the semiconductor material. A method for manufacturing a composite substrate according to the present invention is a method for manufacturing a composite substrate including a functional substrate made of a functional material and a support substrate made of a semiconductor material that supports the functional substrate, and includes: an activation step in which a fast atomic beam is irradiated onto a surface of the functional substrate and onto a surface of a semiconductor substrate made of the semiconductor material so that at least a portion of the irradiation times overlap; a sputtering step that is carried out subsequent to the activation step, in which, after stopping the irradiation of the fast atomic beam onto the surface of the functional substrate, the irradiation of the fast atomic beam onto the surface of the semiconductor substrate is continued to form a sputtered film made of an amorphous body of the sputtered semiconductor material on the surface of the functional substrate; and a bonding step in which the functional substrate on which the sputtered film has been formed and the semiconductor substrate are bonded to obtain a bonded body.

[0008] According to the present invention, it is possible to realize a composite substrate in which a functional substrate and a support substrate are bonded via a bonding layer, and a method for manufacturing the same, which can obtain sufficient bonding strength even if the bonding layer is thin.

[0009] FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a composite substrate according to a first embodiment of the present invention. FIG. 2 is a view showing an example of a manufacturing process for a composite substrate according to the first embodiment of the present invention. FIG. 3 is a view showing an example of a manufacturing process for a composite substrate according to the first embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a composite substrate according to a second embodiment of the present invention. FIG. 5 is a view showing an example of a manufacturing process for a composite substrate according to the second embodiment of the present invention. FIG. 6 is a view showing an example of a manufacturing process for a composite substrate according to the second embodiment of the present invention. FIG. 7 is a schematic cross-sectional view showing a schematic configuration of a composite substrate according to a third embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing a schematic configuration of a composite substrate according to a fourth embodiment of the present invention. FIG. 9 is a view showing observation photographs of Example 1 and a comparative example. FIG. 10 is a table showing EDX analysis results of Example 1 and Example 3. FIG. 11 is a table showing the relationship between FAB irradiation time, thickness of a bonding layer, and bonding strength in a composite substrate. FIG. 12 is a table showing the relationship between FAB irradiation time to a functional substrate and a semiconductor substrate in a composite substrate, and bonding strength.

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part more schematically than in the embodiments, but these are merely examples and do not limit the interpretation of the present invention.

[0011] 1 is a schematic cross-sectional view showing a general configuration of a composite substrate according to a first embodiment of the present invention. The composite substrate 100 in this embodiment is used for various purposes, such as optical elements that constitute optical waveguides, piezoelectric elements that constitute surface acoustic wave (SAW) filters, and various semiconductor elements, and has a structure in which a functional substrate 10 made of a functional material such as a piezoelectric material or a semiconductor material is bonded to a support substrate 30.

[0012] The material of the functional substrate 10 is, for example, LN (LiNbO ３ : lithium niobate) and LT (LiTaO ３ : lithium tantalate), quartz crystal, AlN (aluminum nitride), PZT (Pb(Zr,Ti)O ３A piezoelectric material such as lead zirconate titanate (PZT) is used. The material of the functional substrate 10 can be selected arbitrarily depending on the application of the composite substrate 100. For example, in addition to piezoelectric materials, the functional substrate 10 may be formed using semiconductor materials such as SiC, InP, GaN, GaP, and diamond, materials having an electro-optic effect such as lithium niobate-lithium tantalate and KTP (potassium titanate phosphate), quartz, glass, etc. In addition to these, functional substrates 10 made of various functional materials can be used depending on the application of the composite substrate 100.

[0013] The support substrate 30 supports the functional substrate 10. Any appropriate substrate can be used as the support substrate 30. The support substrate 30 may be made of a single crystal or a polycrystalline material. The functional substrate 10 and the support substrate 30 are directly bonded to each other.

[0014] The support substrate 30 may be made of a semiconductor material such as Si, Ge, SiC, InP, GaN, or sapphire. Alternatively, the support substrate 30 may be made of Si(1-x)Ox (where 0.008≦x≦0.408) or SOI (Silicon on Insulator). The thickness of the support substrate 30 is, for example, 0.2 to 1 mm, but any other appropriate thickness may be used.

[0015] Although not shown, the composite substrate 100 may further include any layer. The type, function, number, combination, arrangement, etc. of such layers may be appropriately set depending on the purpose.

[0016] 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. The size of the composite substrate 100 can be appropriately set depending on the purpose, for example, with a wafer (substrate) diameter of 50 mm to 150 mm.

[0017] 2 and 3 are diagrams showing an example of a manufacturing process for the composite substrate according to the first embodiment of the present invention.

[0018] 2A shows a preparation step in the manufacturing process of the composite substrate 100. In this step, a functional substrate 10 made of a functional material and having a predetermined thickness is prepared.

[0019] 2(b) shows an activation step in the manufacturing process of the composite substrate 100. In this step, for example, a semiconductor substrate 30A made of a semiconductor material having a predetermined thickness is prepared, and activation processing is performed by irradiating the surfaces of the functional substrate 10 prepared in the preparation step of FIG. 2(a) and the semiconductor substrate 30A with a fast atom beam (hereinafter referred to as FAB) using a rare gas such as Ar as the atomic species for a predetermined time. The FAB irradiation time in this case is preferably, for example, about 15 to 30 seconds.

[0020] FIG. 2(c) shows the sputtering step in the manufacturing process of the composite substrate 100. In this step, the FAB irradiation on the functional substrate 10 side, which was irradiated to both the functional substrate 10 and the semiconductor substrate 30A in the activation step of FIG. 2(b), is stopped, and the FAB irradiation on the semiconductor substrate 30A side is continued for a predetermined time. The FAB irradiation time at this time is preferably, for example, about 30 to 600 seconds. As a result, the semiconductor material constituting the semiconductor substrate 30A is sputtered and attached to the surface of the functional substrate 10, forming a sputtered film 30B on the functional substrate 10 side, which is made of the same semiconductor material as the semiconductor substrate 30A. As described below, the thickness of the bonding layer 33 (see FIG. 3(f)) in the manufactured composite substrate 100 is preferably 0.3 nm to 3 nm. Therefore, in the sputtering step, the sputtered film 30B is preferably formed to a thickness of 0.3 nm to 3 nm.

[0021] Figure 3(d) shows the bonding step in the manufacturing process of the composite substrate 100. In this step, the functional substrate 10 on which the sputtered film 30B has been formed in the sputtering step of Figure 2(c) is bonded to the semiconductor substrate 30A. As a result, the semiconductor substrate 30A and the sputtered film 30B are integrated to form the support substrate 30, and a bonded body of the functional substrate 10 and the support substrate 30 is obtained. Note that in Figure 3(d) and subsequent figures, the positional relationship between the functional substrate 10 and the semiconductor substrate 30A (support substrate 30) is illustrated upside down compared to Figures 2(a) to 2(c).

[0022] Fig. 3(e) shows a bonded body obtained after the bonding step of Fig. 3(d). By the bonding step of Fig. 3(d), the semiconductor substrate 30A and the sputtered film 30B are integrated as described above, thereby forming a support substrate 30 having a bonding interface 40 therein, and a bonded body as shown in Fig. 3(e) is obtained.

[0023] In the bonded structure of FIG. 3( e), a first functional layer 11 mainly composed of a crystalline functional material and a second functional layer 12 disposed closer to the support substrate 30 than the first functional layer 11 are formed on the functional substrate 10. The second functional layer 12 is mainly composed of an amorphous functional material and is a layer containing rare gas atoms such as Ar irradiated as FAB in the activation step of FIG. 2( b). Meanwhile, the support substrate 30 is formed with a first support layer 31 that does not contact the bonding interface 40, a second support layer 32 that is disposed closer to the functional substrate 10 than the first support layer 31 and is in contact with the bonding interface 40, and a bonding layer 33 that is disposed closer to the functional substrate 10 than the second support layer 32 and is in contact with the bonding interface 40. The second support layer 32 is mainly composed of an amorphous semiconductor material and is a layer containing rare gas atoms such as Ar irradiated as FAB in the activation step of FIG. 2( b) and the sputtering step of FIG. 2( c). The bonding layer 33 corresponds to the sputtered film 30B before bonding, and is a layer that forms a bonding portion with the functional substrate 10.

[0024] The second functional layer 12 in the functional substrate 10 and the second support layer 32 and bonding layer 33 in the support substrate 30 may contain other atomic species that are mixed into these layers during the sputtering process shown in Fig. 2(c), such as Fe atoms and Al atoms that constitute the jig or base portion used to fix the semiconductor substrate 30A. Details of these layers will be described later.

[0025] 3(f) shows a thinning step in the manufacturing process of the composite substrate 100. In this step, the functional substrate 10 is polished to a predetermined thickness for the bonded body shown in FIG. 3(e) to thin it. For example, the functional substrate 10 can be polished to thin it using grinding, CMP (Chemical Mechanical Polishing), surface planarization using a gas cluster ion beam, or the like.

[0026] Through the above steps, the composite substrate 100 having the structure shown in FIG. 1 is manufactured.

[0027] 3(d) and the thin plate processing step of FIG. 3(f), an annealing step of heating the bonded body to a predetermined temperature may be performed. The heating temperature at this time is preferably, for example, about 75 to 250°C, and more preferably 100 to 250°C. This can improve the bonding strength of the functional substrate 10.

[0028] 4 is a schematic cross-sectional view showing a general configuration of a composite substrate according to a second embodiment of the present invention. The composite substrate 110 according to this embodiment has a structure in which the functional substrate 10 is bonded to the support substrate 30 via the insulating layer 20, as compared with the composite substrate 100 shown in FIG. 1 described in the first embodiment.

[0029] The insulating layer 20 made of an insulating material is disposed between the functional substrate 10 and the support substrate 30. The insulating material constituting the insulating layer 20 can be, for example, an oxide or nitride of Si, Ta, Al, Nb, Hf, or the like, and is preferably silicon oxide. The insulating layer 20 may also be formed by combining multiple layers made of different insulating materials. For example, by disposing a layer made of silicon oxide and a layer made of silicon oxynitride between the functional substrate 10 and the support substrate 30, respectively, the combination of these layers can be used as the insulating layer 20. Silicon oxynitride is silicon oxide in which some of the oxygen atoms constituting silicon oxide are replaced with nitrogen atoms.

[0030] The insulating layer 20 can be formed by any suitable method, such as sputtering, vacuum evaporation, physical vapor deposition such as ion beam assisted deposition (IAD), chemical vapor deposition, or atomic layer deposition (ALD). The insulating layer 20 can be formed at a temperature of, for example, room temperature (25° C.) to 300° C.

[0031] In this embodiment, as in the first embodiment, the composite substrate 110 may further include any layer. The type, function, number, combination, arrangement, etc. of such layers may be appropriately set depending on the purpose. Furthermore, the composite substrate 110 may be manufactured in any appropriate shape depending on the purpose.

[0032] 5 and 6 are diagrams showing an example of a manufacturing process for a composite substrate according to the second embodiment of the present invention.

[0033] Fig. 5A shows a preparation step in the manufacturing process of the composite substrate 110. In this step, a functional substrate 10 having a predetermined thickness is prepared, similar to the step shown in Fig. 2A described in the first embodiment.

[0034] Fig. 5(b) shows an insulating layer forming step in the manufacturing process of the composite substrate 110. In this step, an insulating layer 20 is formed by depositing, for example, an amorphous silicon oxide film to a predetermined thickness on the surface of the functional substrate 10 prepared in the preparation step of Fig. 5(a).

[0035] 5C shows an activation step in the manufacturing process of the composite substrate 110. In this step, for example, a semiconductor substrate 30A made of a semiconductor material having a predetermined thickness is prepared, and activation processing is performed by irradiating the surfaces of the insulating layer 20 formed on the functional substrate 10 in the insulating layer forming step of FIG. 5B and the semiconductor substrate 30A with FAB using a rare gas such as Ar as an atomic species for a predetermined time, similar to the step of FIG. 2B described in the first embodiment.

[0036] FIG. 5(d) shows the sputtering step in the manufacturing process of the composite substrate 110. In this step, similar to the step of FIG. 2(c) described in the first embodiment, the FAB irradiation on the functional substrate 10 side (insulating layer 20 side) of the functional substrate 10 and the semiconductor substrate 30A, respectively, is stopped, and 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 attached to the surface of the insulating layer 20 formed on the functional substrate 10, forming a sputtered film 30B made of the same semiconductor material as the semiconductor substrate 30A on the functional substrate 10 side (insulating layer 20 side). As in the first embodiment, the thickness of the bonding layer 33 (see FIG. 6(g)) in the manufactured composite substrate 110 is preferably 0.3 nm to 3 nm. Therefore, in the sputtering step, the sputtered film 30B is preferably formed to a thickness of 0.3 nm to 3 nm.

[0037] FIG. 6( e) shows the bonding step in the manufacturing process of the composite substrate 110. In this step, similar to the step of FIG. 3( d) described in the first embodiment, the functional substrate 10, on which the sputtered film 30B has been formed on the insulating layer 20 in the sputtering step of FIG. 5( d), is bonded to the semiconductor substrate 30A. As a result, the semiconductor substrate 30A and the sputtered film 30B are bonded and integrated to form the support substrate 30, and a bonded body of the functional substrate 10, the insulating layer 20, and the support substrate 30 is obtained. Note that in FIG. 6( e) and subsequent figures, the positional relationship between the functional substrate 10 and the semiconductor substrate 30A (support substrate 30) is illustrated upside down compared to FIGS. 5( a) to 5( d).

[0038] Fig. 6(f) shows a bonded body obtained after the bonding step of Fig. 6(e) . By the bonding step of Fig. 6(e) , the semiconductor substrate 30A and the sputtered film 30B are integrated as described above, thereby forming a support substrate 30 having a bonding interface 40 therein, and a bonded body as shown in Fig. 6(f) is obtained.

[0039] 6( f), the insulating layer 20 includes a first insulating layer 21 mainly made of an insulating material and a second insulating layer 22 disposed closer to the support substrate 30 than the first insulating layer 21. The second insulating layer 22 is mainly made of an amorphous insulating material and is a layer containing rare gas atoms such as Ar irradiated by FAB in the activation step of FIG. 5( c). On the other hand, the support substrate 30 includes, as in the first embodiment, a first support layer 31 not in contact with the bonding interface 40, a second support layer 32 disposed closer to the functional substrate 10 than the first support layer 31 and in contact with the bonding interface 40, and a bonding layer 33 disposed closer to the functional substrate 10 than the second support layer 32 and in contact with the bonding interface 40.

[0040] Fig. 6(g) shows a thinning process in the manufacturing process of the composite substrate 110. In this process, similar to the process of Fig. 3(f) described in the first embodiment, the functional substrate 10 of the bonded body shown in Fig. 6(f) is polished to a predetermined thickness to thin the functional substrate 10.

[0041] Through the above steps, the composite substrate 110 having the structure shown in FIG. 4 is manufactured.

[0042] In this embodiment, similarly to the first embodiment, an annealing step of heating the bonded body to a predetermined temperature may be performed between the bonding step of FIG. 6( e ) and the thin plate processing step of FIG. 6( g ).

[0043] 7 is a schematic cross-sectional view showing a general configuration of a composite substrate according to a third embodiment of the present invention. A composite substrate 120 according to this embodiment has a structure in which a functional substrate 10 is directly bonded to a support substrate 30, similar to the composite substrate 100 shown in FIG. 1 described in the first embodiment.

[0044] In the composite substrate 120 of this embodiment, a ridge portion 50 is provided in the functional substrate 10 in order to use a portion of the functional substrate 10 as an optical waveguide. The ridge portion 50 is a portion of the functional substrate 10 formed by providing a step in the functional substrate 10 so that the thickness is greater than that of other portions. This ridge portion 50 is provided by performing a process (ridge processing) to form a step in a portion of the functional substrate 10 after the thin plate processing process shown in FIG. 3( f) described in the first embodiment. For example, ridge processing of the functional substrate 10 can be achieved by processing using laser light or dry etching such as RIE (Reactive Ion Etching). Note that other processes may be performed thereafter. As a result, the bonding interface 40 is included within the support substrate 30 in this embodiment as well.

[0045] 8 is a schematic cross-sectional view showing a general configuration of a composite substrate according to a fourth embodiment of the present invention. Similar to the composite substrate 110 of FIG. 4 described in the second embodiment, a composite substrate 130 of this embodiment has a structure in which a functional substrate 10 is bonded to a support substrate 30 via an insulating layer 20.

[0046] The material and shape of the functional substrate 10 are the same as those described in the third embodiment. That is, in the composite substrate 130 of this embodiment, a ridge portion 50 is also provided in the functional substrate 10 in order to use a portion of the functional substrate 10 as an optical waveguide. This ridge portion 50 is provided by performing processing (ridge processing) to form a step in a portion of the functional substrate 10 after the thin plate processing step of FIG. 6( g) described in the second embodiment, for example. As a result, the bonding interface 40 is included inside the support substrate 30 in this embodiment as well.

[0047] Examples for verifying the structure of the composite substrate according to the present invention will be specifically described below. Unless otherwise specified, the following procedures were carried out at room temperature.

[0048] Example 1 A bonded body was produced according to the manufacturing process described with reference to Figures 2 and 3. Specifically, an LT substrate and a silicon substrate, each having a diameter of 4 inches and a thickness of 500 µm, were prepared, and the LT substrate was used as the functional substrate 10, and the silicon substrate was used as the semiconductor substrate 30A.

[0049] Then, after cleaning the surfaces of the functional substrate 10 and the semiconductor substrate 30A, the functional substrate 10 and the semiconductor substrate 30A were placed in a vacuum chamber in which FAB guns were installed facing up and down, so that the substrates were located within the irradiation ranges of the FAB guns and the surfaces of the two substrates faced each other. －６ The chamber was evacuated to a pressure of the Pa range, and the surfaces of the functional substrate 10 and the semiconductor substrate 30A were simultaneously irradiated with FAB using Ar gas (acceleration voltage 1 kV, Ar flow rate 27 sccm) from each FAB gun for 15 seconds.

[0050] Thereafter, the FAB irradiation on the functional substrate 10 side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for another 90 seconds (total of 105 seconds). At this time, in order to prevent the internal pressure of the vacuum chamber from changing before and after the FAB irradiation on the functional substrate 10 side was stopped, the FAB irradiation from the FAB gun on the functional substrate 10 side to the surface of the functional substrate 10 was stopped while the supply of Ar gas to the FAB gun on the functional substrate 10 side was continued. As a result, a sputtered film 30B was formed on the surface of the functional substrate 10.

[0051] Next, the functional substrate 10 on which the sputtered film 30B was formed was directly bonded to the semiconductor substrate 30A. Specifically, the beam-irradiated surfaces of both substrates were overlapped, and the two substrates were bonded together by applying a pressure of 10,000 N at room temperature for 2 minutes to obtain a bonded body. This resulted in the composite substrate 100 having the structure shown in FIG. 1.

[0052] The bonding strength of the composite substrate 100 thus obtained was evaluated by the crack opening method, and was found to be 1.45 J / m ２ and had sufficient bonding strength.

[0053] Example 2 The functional substrate 10 and the semiconductor substrate 30A similar to those in Example 1 were placed in a vacuum chamber. －６ With the vacuum pumped to the Pa range, FAB using Ar gas was irradiated from each FAB gun simultaneously onto the surfaces of the functional substrate 10 and the semiconductor substrate 30A under the same conditions as in Example 1 for 30 seconds.

[0054] Thereafter, the FAB irradiation on the functional substrate 10 side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for another 90 seconds (total of 120 seconds). At this time, as in Example 1, in order to prevent the internal pressure of the vacuum chamber from changing before and after the FAB irradiation on the functional substrate 10 side was stopped, while the supply of Ar gas to the FAB gun on the functional substrate 10 side was continued. As a result, a sputtered film 30B was formed on the surface of the functional substrate 10.

[0055] Next, similarly to Example 1, the functional substrate 10 on which the sputtered film 30B was formed was directly bonded to the semiconductor substrate 30A, thereby obtaining the composite substrate 100 having the structure shown in FIG.

[0056] The bonding strength of the composite substrate 100 thus obtained was evaluated by the crack opening method, and was found to be 1.63 J / m ２ The bonding strength was improved compared to Example 1.

[0057] Example 3 A bonded body was produced according to the manufacturing process described with reference to Figures 5 and 6. Specifically, an LT substrate and a silicon substrate, each having a diameter of 4 inches and a thickness of 500 µm, were prepared, and the LT substrate was used as the functional substrate 10, and the silicon substrate was used as the semiconductor substrate 30A. Silicon oxide was then sputtered onto the surface of the functional substrate 10 to form an insulating layer 20 made of a silicon oxide film.

[0058] Thereafter, similarly to Example 1, the surfaces of the functional substrate 10 and the semiconductor substrate 30A on which the insulating layer 20 was formed were cleaned, and then, in a vacuum chamber in which FAB guns were respectively installed facing up and down, the functional substrate 10 and the semiconductor substrate 30A were arranged so that these substrates were respectively located within the irradiation range of each FAB gun and so that the silicon oxide surface (the surface on the insulating layer 20 side) of the functional substrate 10 and the surface of the semiconductor substrate 30A faced each other. －６ The chamber was evacuated to a pressure of the Pa range, and the surfaces of the functional substrate 10 and the semiconductor substrate 30A were simultaneously irradiated with Ar gas from each FAB gun under the same conditions as in Example 1 for 15 seconds.

[0059] Thereafter, the FAB irradiation on the functional substrate 10 side was stopped, while the FAB irradiation on the semiconductor substrate 30A side was continued for another 285 seconds (300 seconds in total). At this time, as in Examples 1 and 2, in order to prevent a change in the internal pressure of the vacuum chamber before and after the FAB irradiation on the functional substrate 10 side was stopped, while the supply of Ar gas to the FAB gun on the functional substrate 10 side was continued. As a result, a sputtered film 30B was formed on the surface of the insulating layer 20 in the functional substrate 10.

[0060] Next, similarly to Examples 1 and 2, the functional substrate 10 having the sputtered film 30B formed on the surface of the insulating layer 20 was directly bonded to the semiconductor substrate 30A, thereby obtaining a composite substrate 110 having the structure shown in FIG. 4.

[0061] The bonding strength of the composite substrate 110 thus obtained was evaluated by the crack opening method, and was found to be 2.01 J / m ２ The bonding strength was further improved compared to Examples 1 and 2.

[0062] In the above Examples 1 to 3, the FAB irradiation from the FAB gun to the functional substrate 10 and the semiconductor substrate 30A was performed for a predetermined time, and then the FAB irradiation on the functional substrate 10 side was stopped first. This allows the time required to form the sputtered film 30B to be used for cooling the functional substrate 10, thereby reducing the impact of warpage on the composite substrates 100, 110 after bonding. In particular, when the functional substrate 10 has a larger thermal expansion coefficient than the semiconductor substrate 30A, stopping the FAB irradiation on the functional substrate 10 side first can be more effective in reducing warpage after bonding.

[0063] Comparative Example In order to confirm the effect of the present invention, as a comparative example, the functional substrate 10 and the semiconductor substrate 30A similar to those in Example 1 were placed in a vacuum chamber, and the inside of the vacuum chamber was heated to 1000 K. －６ With the chamber evacuated to a pressure in the Pa range, FAB irradiation was performed on the semiconductor substrate 30A side only for 90 seconds, without FAB irradiation on the functional substrate 10 side. The FAB irradiation conditions on the semiconductor substrate 30A side at this time were the same as in Example 1. As a result, a sputtered film 30B was formed on the surface of the insulating layer 20 in the functional substrate 10.

[0064] Next, similarly to Examples 1 to 3, the functional substrate 10 on which the sputtered film 30B was formed was directly bonded to the semiconductor substrate 30A, thereby obtaining the composite substrate 100 having the structure shown in FIG.

[0065] The bonding strength of the composite substrate 100 thus obtained was evaluated by the crack opening method, and was found to be 0.74 J / m ２Therefore, sufficient bonding strength was not obtained.

[0066] (Confirmation of Layer Structure) A cross section including the bonding interface 40 of the composite substrate 100 produced in each of Example 1 and the comparative example was observed with a transmission electron microscope (TEM) to confirm the layer structure of the composite substrate 100. Fig. 9(a) shows an observation photograph of Example 1, and Fig. 9(b) shows an observation photograph of the comparative example.

[0067] 9A shows the observation photograph of Example 1. It can be seen that two layers are formed inside the functional substrate 10. These layers are designated, in order from the side furthest from the support substrate 30, as a first functional layer 11 and a second functional layer 12. It can also be seen that three layers are formed inside the support substrate 30. These layers are designated, in order from the side furthest from the functional substrate 10, as a first support layer 31, a second support layer 32, and a bonding layer 33. The second functional layer 12 and the bonding layer 33 are in contact with each other, and a bonding interface 40 formed in the bonding process described above exists between the second support layer 32 and the bonding layer 33. That is, in the bonding process, the surface of the second functional layer 12 in the semiconductor substrate 30A before bonding and the surface of the sputtered film 30B formed on the functional substrate 10 before bonding are bonded to each other, whereby the sputtered film 30B becomes the bonding layer 33, and a bonded body of the functional substrate 10 and the support substrate 30 having the bonding interface 40 inside the support substrate 30 is formed.

[0068] 9A, it can be seen that the second functional layer 12 does not have a crystalline structure and is composed of amorphous LT, whereas the first functional layer 11 is composed of crystalline LT. That is, in Example 1, it can be seen that the second functional layer 12, which corresponds to the portion of the functional substrate 10 before bonding from the surface irradiated with FAB in the activation step to a predetermined depth, is formed as a layer of amorphous LT, which is the material of the functional substrate 10.

[0069] 9A, it can be seen that, in contrast to the first support layer 31 made of crystalline Si, the second support layer 32 and the bonding layer 33 do not have a crystalline structure and are made of amorphous Si. That is, in Example 1, it can be seen that the second support layer 32, which corresponds to the portion of the semiconductor substrate 30A before bonding from the surface irradiated with FAB in the activation step and the sputtering step to a predetermined depth, and the bonding layer 33, which corresponds to the sputtered film 30B formed on the surface of the functional substrate 10 in the sputtering step, are each formed as a layer in which silicon, which is the material of the support substrate 30, has been made amorphous.

[0070] 9(b), the functional substrate 10 is composed of only a first functional layer 11 having a crystalline structure, and the second functional layer 12 as in Example 1 is not formed on the functional substrate 10. That is, in the comparative example, the functional substrate 10 before bonding is not irradiated with FAB in the activation step, and therefore the second functional layer 12 made of an amorphous film of LT is not formed, and it can be seen that this results in a lower bonding strength than in Example 1.

[0071] As described above, in Example 3, an insulating layer 20 made of a silicon oxide film is formed on the surface of the functional substrate 10 before bonding, and after activating the surface of this insulating layer 20, a sputtered film 30B is formed, and the functional substrate 10 and the semiconductor substrate 30A are bonded together. Therefore, in the composite substrate 110 of Example 3, two layers corresponding to the first functional layer 11 and the second functional layer 12 in FIG. 9( a) are formed in the insulating layer 20 rather than in the functional substrate 10. That is, in Example 3, a first insulating layer 21 located on the side farther from the support substrate 30 and a second insulating layer 22 corresponding to the portion of the insulating layer 20 from the surface irradiated with FAB in the activation step before bonding to a predetermined depth are formed.

[0072] (Structural Analysis) In a cross section including the bonding interface 40 of the composite substrate 100 produced in Example 1, EDX analysis was performed on each of the aforementioned first functional layer 11, second functional layer 12, first support layer 31, second support layer 32, and bonding layer 33, thereby carrying out a structural analysis of the composite substrate 100. Similarly, in a cross section including the bonding interface 40 of the composite substrate 110 produced in Example 3, EDX analysis was performed on each of the aforementioned first insulating layer 21, second insulating layer 22, first support layer 31, second support layer 32, and bonding layer 33, thereby carrying out a structural analysis of the composite substrate 110.

[0073] 10(a) shows the proportions of elemental components obtained from the EDX analysis results for each of the first functional layer 11, the second functional layer 12, the first support layer 31, the second support layer 32, and the bonding layer 33 in Example 1. In addition, for the second functional layer 12, the second support layer 32, and the bonding layer 33, the measurement results of the thickness of each layer are also shown.

[0074] 10( a), the rare gas Ar used in the FAB irradiation is contained in greater amounts in the second functional layer 12 and the second support layer 32 than in the first functional layer 11 and the first support layer 31. The Ar content is also higher in the second support layer 32 than in the second functional layer 12. These results indicate that the second functional layer 12 and the second support layer 32 contain Ar resulting from the FAB irradiation during the activation process and the sputtering process, respectively, and that the second support layer 32 was exposed to FAB for a longer time than the second functional layer 12, resulting in the second functional layer 12 containing more Ar. Although the table in FIG. 10( a) indicates that the first functional layer 11 and the first support layer 31 contain small amounts of Ar, this may not always be the case.

[0075] 10A, the Ar content in the bonding layer 33 is lower than that in the second functional layer 12 and the second support layer 32. This shows that the Ar irradiated as FAB in the sputtering process is not contained in large amounts in the bonding layer 33, which corresponds to the sputtered film 30B.

[0076] 10( a) also shows that the bonding layer 33 contains more Al than the other layers. This is thought to be because, in the sputtering process, the FAB is irradiated not only onto the semiconductor substrate 30A but also onto the jig and base portion that fix the semiconductor substrate 30A, and these components are mixed into the bonding layer 33.

[0077] 10(b) shows the proportions of elemental components obtained from the EDX analysis results for each of the first insulating layer 21, the second insulating layer 22, the first supporting layer 31, the second supporting layer 32, and the bonding layer 33 in Example 3. For the second supporting layer 32 and the bonding layer 33, the measurement results of the thickness of each layer are also shown.

[0078] In the insulating layer 20 of Example 3, unlike the functional substrate 10 of Example 1, both the first insulating layer 21 and the second insulating layer 22 are composed of amorphous silicon oxide. Therefore, the boundary between the first insulating layer 21 and the second insulating layer 22 is difficult to distinguish from TEM observation images. Therefore, the thickness of the second insulating layer 22 is not listed in the table of FIG. 10( b). However, similar to the functional substrate 10 of Example 1, the insulating layer 20 of Example 3 is also considered to have a second insulating layer 22 composed of an amorphous material containing a large amount of Ar, similar to the second functional layer 12, near the bonding layer 33 (e.g., within a range of about several nanometers from the boundary surface with the bonding layer 33). Therefore, in the table of FIG. 10( b), the EDX analysis results for the insulating layer 20 near the boundary surface with the bonding layer 33 are shown as the EDX analysis results for the second insulating layer 22.

[0079] As with the table of FIG. 10( a), the table of FIG. 10( b) shows that the Ar gas, which is the rare gas used in the FAB irradiation, is contained in greater amounts in the second insulating layer 22 and the second supporting layer 32 than in the first insulating layer 21 and the first supporting layer 31. The Ar content is also higher in the second supporting layer 32 than in the second insulating layer 22. From these results, it can be seen that in Example 3, as in Example 1, the second insulating layer 22 and the second supporting layer 32 contain Ar resulting from the FAB irradiation in the activation process and the sputtering process, respectively, and that the second insulating layer 22 contains more Ar because the FAB irradiation time is longer for the second supporting layer 32 than for the second insulating layer 22. Note that, although the table of FIG. 10( b) shows that the first insulating layer 21 and the first supporting layer 31 contain small amounts of Ar, this may not always be the case.

[0080] 10B, the content of Ar in the bonding layer 33 is lower than that in the second insulating layer 22 and the second support layer 32. This shows that, similarly to Example 1, in Example 3 as well, the Ar irradiated as FAB in the sputtering process is not contained in a large amount in the bonding layer 33 corresponding to the sputtered film 30B.

[0081] Also, in the table of FIG. 10(b), as in the table of FIG. 10(a), it can be seen that the bonding layer 33 contains more Al than the other layers for the reasons described above.

[0082] (Relationship between thickness of bonding layer and bonding strength) Among the manufacturing parameters described in Example 3, the FAB irradiation time to the semiconductor substrate 30A in the sputtering process was changed, and the other parameters were kept the same as in Example 3. Using multiple composite substrates 110 each manufactured, the relationship between the thickness of the bonding layer 33 in the support substrate 30 and the bonding strength was measured.

[0083] 11 is a table showing the relationship between the FAB irradiation time, the thickness of the bonding layer 33, and the bonding strength of the composite substrate 110. The table in FIG. 11 shows the FAB irradiation time for the semiconductor substrate 30A in the activation step (combined activation step and sputtering step), the thickness of the bonding layer 33, and the bonding strength of each composite substrate 110 produced when the FAB irradiation time for the functional substrate 10 and the semiconductor substrate 30A in the activation step is fixed at 15 seconds, and the FAB irradiation time for the semiconductor substrate 30A in the sputtering step is changed to 50 seconds, 90 seconds, 195 seconds, 285 seconds, and 585 seconds. The case where the FAB irradiation time in the sputtering step is set to 285 seconds corresponds to Example 3 described above.

[0084] From the table of FIG. 11, it can be seen that if the thickness of the bonding layer 33 is 0.3 nm or more, the bonding strength is 1 J / m ２ This shows that a sufficient bonding strength can be obtained. ２ To obtain the above bonding strength, the bonding layer needs to have a thickness of at least about 2 nm, whereas in composite substrate 110 to which the present invention is applied, if the thickness of bonding layer 33 is 0.3 nm or more, it is possible to obtain a bonding strength equal to or greater than that of the composite substrate described in Patent Document 1. This also applies to the other composite substrates 100, 120, and 130.

[0085] From the viewpoint of shortening the manufacturing time in the sputtering process and miniaturizing the product, it is preferable to make the thickness of bonding layer 33 as thin as possible as long as sufficient bonding strength can be obtained in manufactured composite substrates 100 to 130. For example, if the maximum thickness of bonding layer 33 is 3 nm, based on the above results, the thickness of bonding layer 33 in composite substrates 100 to 130 can be set to 0.3 nm or more and 3 nm or less.

[0086] (Relationship between FAB irradiation time in activation process and bonding strength) Among the manufacturing parameters described in Examples 1 and 2, the FAB irradiation time to the functional substrate 10 in the activation process was changed, and the other parameters were kept the same as in Examples 1 and 2. Using multiple composite substrates 100 each manufactured, the relationship between the thickness of the bonding layer 33 in the support substrate 30 and the bonding strength was measured.

[0087] 12 is a table showing the relationship between the FAB irradiation time and the bonding strength of the functional substrate 10 and the semiconductor substrate 30A in the composite substrate 100. The table in FIG. 12 shows the FAB irradiation time for the semiconductor substrate 30A in the activation process, which is varied from 15 seconds to 30 seconds, 300 seconds, and 510 seconds, and the FAB irradiation time for the semiconductor substrate 30A in the sputtering process is fixed at 90 seconds. The table shows the FAB irradiation time for the semiconductor substrate 30A in the activation process and the sputtering process combined, and the bonding strength of each composite substrate 100 produced. Note that the cases where the FAB irradiation time in the sputtering process is 15 seconds and 30 seconds correspond to the above-mentioned Examples 1 and 2, respectively.

[0088] From the table of FIG. 12, if the FAB irradiation time in the activation step is 300 seconds or less, the bonding strength is 1 J / m ２ While sufficient bonding strength is obtained as described above, it can be seen that the bonding strength decreases when the FAB irradiation time in the activation step exceeds 300 seconds. This is thought to be because the longer the FAB irradiation time of the functional substrate 10 in the activation step, the greater the surface roughness of the functional substrate 10 becomes, and when this surface roughness exceeds a certain level, it leads to a decrease in bonding strength.

[0089] 11 and 12 are merely examples. These values ​​may vary depending on the types of functional and semiconductor materials used in the functional substrate 10 and the semiconductor substrate 30A, the voltage and current of the FAB, the rare gas flow rate, etc. Therefore, instead of adjusting the FAB irradiation time, it is also possible to form the bonding layer 33 with a desired thickness by adjusting the voltage, current, rare gas flow rate, etc. of the FAB.

[0090] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0091] (1) Composite substrates 100 to 130 each include a functional substrate 10 made of a functional material and a support substrate 30 made of a semiconductor material and bonded to the functional substrate 10 to support the functional substrate 10. The functional substrate 10 includes a first layer (first functional layer 11 or first insulating layer 21) and a second layer (second functional layer 12 or second insulating layer 22) made of an amorphous material containing a rare gas and disposed closer to the support substrate 30 than the first layer. The support substrate 30 includes a first support layer 31, a second support layer 32 made of an amorphous material of a semiconductor material containing a rare gas and disposed closer to the functional substrate 10 than the first support layer 31, and a bonding layer 33 made of an amorphous material of a semiconductor material and disposed in contact with the functional substrate 10. By doing this, it is possible to realize composite substrates 100 to 130 in which a functional substrate 10 and a support substrate 30 are bonded via a bonding layer 33, and which are capable of obtaining sufficient bonding strength even if the thickness of the bonding layer 33 is thin.

[0092] (2) In the composite substrates 100 and 120, the functional substrate 10 has a first functional layer 11 made of a crystalline body of a functional material and a second functional layer 12 made of an amorphous body of the functional material and in contact with the bonding layer 33. In this configuration, the first layer is the first functional layer 11, and the second layer is the second functional layer 12. As a result, it is possible to realize the composite substrates 100 and 120 that can obtain sufficient bonding strength even when the functional substrate 10 and the support substrate 30 are directly bonded without the insulating layer 20 therebetween.

[0093] (3) In the composite substrates 110 and 130, the functional substrate 10 is bonded to the support substrate 30 via an insulating layer 20 made of an insulating material, and the insulating layer 20 has a first insulating layer 21 made of an insulating material and a second insulating layer 22 made of an amorphous insulating material and in contact with the bonding layer 33. In this configuration, the first layer is the first insulating layer 21, and the second layer is the second insulating layer 22. As a result, even when the functional substrate 10 and the support substrate 30 are bonded via the insulating layer 20, the composite substrates 110 and 130 can be realized that can obtain sufficient bonding strength.

[0094] (4) The thickness of bonding layer 33 in composite substrates 100 to 130 is preferably 0.3 nm or more and 3 nm or less. This allows shortening of manufacturing time and miniaturization of the product while maintaining sufficient bonding strength.

[0095] 10( a) and 10(b), the bonding layer 33 contains a rare gas such as Ar, and the content of the rare gas in the bonding layer 33 is lower than the content of the rare gas in the second support layer 32. The bonding layer 33 may also contain a metal element such as Al. In this manner, the surface of the semiconductor substrate 30A is irradiated with FAB to bond the functional substrate 10 and the semiconductor substrate 30A together using the sputtered film 30B formed on the surface of the functional substrate 10 as the bonding layer 33, and composite substrates 100 to 130 can be fabricated using the semiconductor substrate 30A as the support substrate 30.

[0096] 10A, the first functional layer 11 may contain a rare gas such as Ar or may not contain a rare gas. When the first functional layer 11 contains a rare gas, the content of the rare gas in the first functional layer 11 is lower than the content of the rare gas in the second functional layer 12. The content of the rare gas in the second functional layer 12 is lower than the content of the rare gas in the second support layer 32. In this manner, the surface of the functional substrate 10 before bonding is activated by irradiating the surface of the functional substrate 10 with FAB, and then the functional substrate 10 and the semiconductor substrate 30A are bonded to produce the composite substrates 100, 120.

[0097] 10( b), the first insulating layer 21 may contain a rare gas such as Ar or may not contain a rare gas. When the first insulating layer 21 contains a rare gas, the content of the rare gas in the first insulating layer 21 is lower than the content of the rare gas in the second insulating layer 22. The content of the rare gas in the second insulating layer 22 is also lower than the content of the rare gas in the second support layer 32. In this manner, the surface of the insulating layer 20 is activated by irradiating the surface of the functional substrate 10 before bonding on which the insulating layer 20 has been formed with FAB, and then the insulating layer 20 and the semiconductor substrate 30A are bonded to produce the composite substrates 110 and 130.

[0098] 10( a) and 10(b), the first support layer 31 either contains a rare gas such as Ar or does not contain a rare gas, and when the first support layer 31 contains a rare gas, the content of the rare gas in the first support layer 31 is lower than the content of the rare gas in the second support layer 32. In this manner, the functional substrate 10 and the semiconductor substrate 30A are bonded after FAB irradiation of the surface of the semiconductor substrate 30A, and composite substrates 100 to 130 can be fabricated using the semiconductor substrate 30A as the support substrate 30.

[0099] (9) A method for manufacturing a composite substrate 100, 120 including a functional substrate 10 made of a functional material and a support substrate 30 made of a semiconductor material and supporting the functional substrate 10 includes an activation step (FIG. 2(b)) in which a surface of the functional substrate 10 and a surface of a semiconductor substrate 30A made of a semiconductor material are irradiated with FAB so that at least a portion of the irradiation times overlap, a sputtering step (FIG. 2(c)) performed following the activation step, in which, after stopping the FAB irradiation on the surface of the functional substrate 10, the FAB irradiation on the surface of the semiconductor substrate 30A is continued to sputter a semiconductor material onto the surface of the functional substrate 10, and a bonding step (FIG. 3(d)) in which the functional substrate 10 on which the semiconductor material has been sputtered by the sputtering step and the semiconductor substrate 30A are bonded to obtain a bonded body. In this way, the semiconductor substrate 30A and the sputtered film 30B are integrated to form the support substrate 30, and the composite substrate 100, 120 can be manufactured.

[0100] (10) A method for manufacturing a composite substrate 110, 130 including a functional substrate 10 made of a functional material and a support substrate 30 made of a semiconductor material and supporting the functional substrate 10 includes an insulating layer formation process (FIG. 5(b)) in which an insulating layer 20 made of an insulating material is formed on the surface of the functional substrate 10; an activation process (FIG. 5(c)) in which FAB is irradiated onto the surface of the insulating layer 20 and onto the surface of a semiconductor substrate 30A made of a semiconductor material so that at least a portion of the irradiation times overlap; a sputtering process (FIG. 5(d)) that is carried out following the activation process, in which, after stopping the FAB irradiation onto the surface of the insulating layer 20, the FAB irradiation onto the surface of the semiconductor substrate 30A is continued to sputter a semiconductor material onto the surface of the insulating layer 20; and a bonding process (FIG. 6(e)) in which the functional substrate 10 and the semiconductor substrate 30A are bonded together via the insulating layer 20 onto which the semiconductor material has been sputtered in the sputtering process to obtain a bonded body. In this way, the functional substrate 10 and the support substrate 30 can be bonded together via the insulating layer 20 to produce the composite substrates 110 and 130 .

[0101] (11) In the sputtering steps of Fig. 2(c) and Fig. 5(d), it is preferable to form sputtered film 30B with a thickness of 0.3 nm or more and 3 nm or less. In this way, composite substrates 100 to 130 can be produced that maintain sufficient bonding strength while shortening the manufacturing time and enabling the product to be miniaturized.

[0102] (12) The functional substrate 10 and the semiconductor substrate 30A may be placed in a vacuum chamber in which a first FAB gun and a second FAB gun are installed. In the activation process shown in FIGS. 2(b) and 5(c), a rare gas such as Ar may be supplied to the first FAB gun and the second FAB gun, respectively, and the rare gas-based FAB may be irradiated from the first FAB gun onto the surface of the functional substrate 10 or the insulating layer 20, while the second FAB gun may irradiate the surface of the semiconductor substrate 30A. Furthermore, in the sputtering process shown in FIGS. 2(c) and 5(d), the supply of rare gas to the first FAB gun may be continued while the irradiation of the FAB from the first FAB gun onto the surface of the functional substrate 10 or the insulating layer 20 may be stopped. In this manner, the activation process may be properly performed on the functional substrate 10 and the semiconductor substrate 30A, and the sputtering process may be properly performed on the semiconductor substrate 30A, thereby enabling the fabrication of composite substrates 100-130.

[0103] In the above-described embodiments of the present invention, the first FAB gun irradiates the surface of the functional substrate 10 or the insulating layer 20 with FAB, and the second FAB gun irradiates the surface of the semiconductor substrate 30A with FAB simultaneously. This prevents impurities, such as oxide films, formed on the surface of the semiconductor substrate 30A from adhering to the surface of the functional substrate 10 or the insulating layer 20. However, the present invention is not limited to this. For example, a method may be employed in which the first FAB gun first starts FAB irradiation toward the functional substrate 10, the second FAB gun starts FAB irradiation toward the semiconductor substrate 30A a predetermined time later, and then the FAB irradiation toward the functional substrate 10 is stopped first. This method also achieves the same effects as described above.

[0104] The present invention is not limited to the above-described embodiment, and can be implemented using any components without departing from the spirit of the present invention.

[0105] The above-described embodiments and modifications are merely examples, and the present invention is not limited to these details as long as the features of the invention are not impaired. Furthermore, although various embodiments and modifications have been described above, the present invention is not limited to these details. Other aspects that can be considered within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0106] 10: Functional substrate 11: First functional layer 12: Second functional layer 20: Insulating layer 21: First insulating layer 22: Second insulating layer 30: Support substrate 30A: Semiconductor substrate 30B: Sputtered film 31: First supporting layer 32: Second supporting layer 33: Bonding layer 40: Bonding interface 50: Ridge portion 100, 110, 120, 130: Composite substrate

Claims

1. A composite substrate having a functional substrate made of a functional material and a support substrate made of a semiconductor material and bonded to the functional substrate to support the functional substrate, wherein the functional substrate has a first layer and a second layer disposed closer to the support substrate than the first layer and made of an amorphous material containing a noble gas, and the support substrate has a first support layer, a second support layer disposed closer to the functional substrate than the first support layer and made of an amorphous material of the semiconductor material containing the noble gas, and a bonding layer in contact with the functional substrate and made of an amorphous material of the semiconductor material.

2. The composite substrate according to claim 1, wherein the functional substrate has a first functional layer made of a crystal of the functional material and a second functional layer made of an amorphous material of the functional material and in contact with the bonding layer, the first layer is the first functional layer, and the second layer is the second functional layer.

3. The composite substrate according to claim 1, wherein the functional substrate is bonded to the support substrate via an insulating layer made of an insulating material, the insulating layer has a first insulating layer made of the insulating material and a second insulating layer made of an amorphous material of the insulating material and in contact with the bonding layer, the first layer is the first insulating layer, and the second layer is the second insulating layer.

4. The composite substrate according to claim 2 or 3, wherein the thickness of the bonding layer is 0.3 nm or more and 3 nm or less.

5. The composite substrate according to claim 2 or 3, wherein the bonding layer contains the noble gas, and the content of the noble gas in the bonding layer is less than the content of the noble gas in the second support layer.

6. The composite substrate according to claim 2 or 3, wherein the bonding layer contains a metal element.

7. The composite substrate according to claim 2, wherein the first functional layer contains or does not contain the noble gas, and when the first functional layer contains the noble gas, the content of the noble gas in the first functional layer is less than the content of the noble gas in the second functional layer.

8. The composite substrate according to claim 7, wherein the content of the noble gas in the second functional layer is less than the content of the noble gas in the second support layer.

9. The composite substrate according to claim 3, wherein the first insulating layer contains the rare gas or does not contain the rare gas, and when the first insulating layer contains the rare gas, the content of the rare gas in the first insulating layer is less than the content of the rare gas in the second insulating layer.

10. The composite substrate according to claim 9, wherein the content of the rare gas in the second insulating layer is less than the content of the rare gas in the second support layer.

11. The composite substrate according to claim 2 or 3, wherein the first support layer contains the rare gas or does not contain the rare gas, and when the first support layer contains the rare gas, the content of the rare gas in the first support layer is less than the content of the rare gas in the second support layer.

12. A method for manufacturing a composite substrate including a functional substrate made of a functional material and a support substrate made of a semiconductor material for supporting the functional substrate, the method including: an activation step of irradiating a high-speed atomic beam to the surface of the functional substrate and the surface of the semiconductor substrate made of the semiconductor material so that at least a part of the respective irradiation times overlaps; a sputtering step that is carried out subsequent to the activation step, and after stopping the irradiation of the high-speed atomic beam to the surface of the functional substrate, continues the irradiation of the high-speed atomic beam to the surface of the semiconductor substrate to sputter the semiconductor material onto the surface of the functional substrate; and a bonding step of bonding the functional substrate and the semiconductor substrate onto which the semiconductor material has been sputtered by the sputtering step to obtain a bonded body.

13. A method for manufacturing a composite substrate including a functional substrate made of a functional material and a support substrate made of a semiconductor material for supporting the functional substrate, the method including: an insulating layer forming step of forming an insulating layer made of an insulating material on a surface of the functional substrate; an activation step of irradiating a high-speed atomic beam to a surface of the insulating layer and a surface of a semiconductor substrate made of the semiconductor material such that at least a part of respective irradiation times overlaps; a sputtering step that is performed subsequent to the activation step, and after stopping irradiation of the high-speed atomic beam to the surface of the insulating layer, continues irradiation of the high-speed atomic beam to the surface of the semiconductor substrate to sputter the semiconductor material onto the surface of the insulating layer; and a bonding step of bonding the functional substrate and the semiconductor substrate via the insulating layer on which the semiconductor material has been sputtered by the sputtering step to obtain a bonded body.

14. The method for manufacturing a composite substrate according to claim 12 or 13, wherein in the sputtering step, a sputtered film made of an amorphous body of the semiconductor material sputtered with a thickness of 0.3 nm or more and 3 nm or less is formed on a surface of the functional substrate or the insulating layer.

15. The method for manufacturing a composite substrate according to claim 12 or 13, wherein the functional substrate and the semiconductor substrate are disposed in a vacuum chamber provided with a first high-speed atomic beam gun and a second high-speed atomic beam gun, in the activation step, a rare gas is supplied to the first high-speed atomic beam gun and the second high-speed atomic beam gun, respectively, and the high-speed atomic beam by the rare gas is irradiated from the first high-speed atomic beam gun to the surface of the functional substrate or the insulating layer and from the second high-speed atomic beam gun to the surface of the semiconductor substrate, and in the sputtering step, irradiation of the high-speed atomic beam from the first high-speed atomic beam gun to the surface of the functional substrate or the insulating layer is stopped while continuing supply of the rare gas to the first high-speed atomic beam gun.

16. In the method for manufacturing a composite substrate according to claim 15, in the activation step, irradiation of the high-speed atomic beam from the first high-speed atomic beam gun onto the surface of the functional substrate or the insulating layer and irradiation of the high-speed atomic beam from the second high-speed atomic beam gun onto the surface of the semiconductor substrate are performed simultaneously. A method for manufacturing a composite substrate.

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