Semiconductor device

Abstract

This semiconductor device (1) comprises: a Si substrate (21); an organic film (23) formed above the Si substrate (21); and a functional layer (10) that is disposed on the organic film (23) and serves as a semiconductor layer for receiving and emitting light. A surface of the functional layer (10), the surface being bonded to the organic film (23), is formed of InP.

Description

semiconductor devices

[0001] The present disclosure relates to semiconductor devices.

[0002] 2. Description of the Related Art Conventionally, semiconductor devices in which a semiconductor layer is disposed on the surface of a silicon substrate have been known (see, for example, Patent Document 1).

[0003] JP 2006-245210 A (see abstract)

[0004] The Si substrate transmits light in a certain wavelength band. Therefore, a device configuration is conceivable in which light generated in the semiconductor layer is emitted from the back surface of the Si substrate, or light incident on the back surface of the Si substrate is received by the semiconductor layer. In this case, reducing the loss of light becomes an issue.

[0005] The present disclosure is directed to reducing optical loss in semiconductor devices.

[0006] The semiconductor device of the present disclosure includes a Si substrate, an organic film formed on the Si substrate, and a semiconductor layer provided on the organic film for receiving or emitting light, wherein the surface of the semiconductor layer that is bonded to the organic film is made of InP.

[0007] In the semiconductor device of the present disclosure, the difference in refractive index between the organic film and InP is small, so that light loss can be reduced.

[0008] 1 is a cross-sectional view showing a semiconductor device according to a first embodiment; FIG. 2 is a flowchart showing a method for manufacturing a semiconductor device according to a first embodiment; FIG. 3 is a cross-sectional view showing a process for forming a functional layer on an InP substrate according to a first embodiment via a buffer layer or the like; FIG. 4 is a cross-sectional view showing a process for patterning the functional layer; FIG. 5 is a cross-sectional view showing a process for forming a protective film on the functional layer; FIG. 6 is a cross-sectional view showing a process for forming a stamp for holding the functional layer; FIG. 7 is a cross-sectional view showing a process for peeling the functional layer from the InP substrate; FIG. 8 is a cross-sectional view showing a process for forming an organic film on a Si substrate; FIG. 9 is a cross-sectional view showing a process for transferring the functional layer to the Si substrate; FIG. 10 is a cross-sectional view (A) showing a process for removing the protective film, and FIG. 11 is a cross-sectional view (B) showing a process for forming an electrode; FIG. 11 is a diagram showing a schematic diagram of a test result for the adhesive strength between an organic film having a thickness of 5 nm and the functional layer; FIG. 12 is a diagram showing a schematic diagram of a test result for the adhesive strength between an organic film having a thickness of 11 nm and the functional layer; and FIG. 13 is a graph showing the relationship between the thickness of the organic film and the light transmittance.

[0009] A semiconductor device according to an embodiment will be described with reference to the drawings. The semiconductor device has a functional layer, i.e., a semiconductor layer, that performs a predetermined function.

[0010] The semiconductor device is, for example, a light-emitting element such as an LED (light-emitting diode) or a surface-emitting laser, or a light-receiving element such as a photodiode. Both light-emitting elements and light-receiving elements are collectively called photoelectric conversion elements.

[0011] When the semiconductor device is a light-emitting element, it can be used in a display device such as an LED display, etc. When the semiconductor device is a light-receiving element, it can be used in an optical sensor, a photodetector, an image sensor, a light-receiving portion for optical communication, etc.

[0012] 1 is a cross-sectional view showing the configuration of a semiconductor device 1 according to embodiment 1. The semiconductor device 1 has an underlying substrate 20 and a functional layer 10 disposed on the underlying substrate 20. The functional layer 10 is also referred to as a semiconductor layer or a functional thin film.

[0013] The base substrate 20 has a Si (silicon) substrate 21, a native oxide film 22 formed on the Si substrate 21, and an organic film 23 formed on the native oxide film 22. The Si substrate 21 is a substrate made of Si, and has a main surface 21 a and a back surface 21 b.

[0014] The native oxide film 22 is formed on the main surface 21a of the Si substrate 21 by reaction with oxygen in the air. ２ The native oxide film 22 has a thickness of less than 10 nm, more specifically, 3 nm or less. Note that a similar native oxide film is also formed on the back surface 21 b or side surface of the Si substrate 21, but illustration and description thereof are omitted.

[0015] The organic film 23 is formed of a resin such as PI (polyimide), PA (polyamide), silicone resin, or acrylic resin. Among these resins, PI is the most desirable because of its high heat resistance and chemical resistance, and can prevent poor bonding between the organic film 23 and the functional layer 10 due to, for example, a thermal process. The film thickness of the organic film 23 will be described later.

[0016] The functional layer 10 has a lower cladding layer 11 formed on the organic film 23, an active layer 12 formed on the lower cladding layer 11, an upper cladding layer 13 formed on the active layer 12, and a contact layer 14 formed on the upper cladding layer 13. The active layer 12 is a light-receiving layer here, but may also be a light-emitting layer.

[0017] The lower cladding layer 11 is made of n-InP (n-type indium phosphide). The active layer 12 is made of i-InGaAs (i-type indium gallium arsenide). The upper cladding layer 13 is made of p-InP (p-type indium phosphide). The contact layer 14 is made of p-InGaAs (p-type indium gallium arsenide).

[0018] The thickness of each of the lower cladding layer 11, active layer 12, upper cladding layer 13, and contact layer 14 is several hundred nanometers to 1 μm. The active layer 12 is also referred to as an InGaAs layer or a photoelectric conversion layer. The lower cladding layer 11 and upper cladding layer 13 are also referred to as an InP layer or an InP cladding layer. The contact layer 14 is a layer on whose surface an electrode 18 ( FIG. 10B ) and the like are formed.

[0019] The stacked structure, in which the active layer 12, an InGaAs layer, is sandwiched between the lower cladding layer 11 and the upper cladding layer 13, both of which are InP layers, converts light with a wavelength of 900 nm or longer into electrical energy. In other words, the semiconductor device 1 functions as a light-receiving element. Light with a wavelength of 900 nm or longer includes near-infrared light and short-wave infrared (SWIR) light.

[0020] The active layer 12 can also be used as a light-emitting layer. In this case, the stacked structure in which the active layer 12 is sandwiched between the lower cladding layer 11 and the upper cladding layer 13 emits light with a wavelength of 900 nm or more when a voltage is applied. In other words, the semiconductor device 1 also functions as a light-emitting element.

[0021] The Si substrate 21 has the property of transmitting light with a wavelength of 900 nm or more. Light L with a wavelength of 900 nm or more that is incident on the back surface 21 b of the Si substrate 21 passes through the Si substrate 21 and is received by the functional layer 10. When the active layer 12 is used as a light-emitting layer, light L emitted from the functional layer 10 passes through the Si substrate 21 and is emitted from the back surface 21 b.

[0022] <Method of Manufacturing Semiconductor Device> Next, a method of manufacturing the semiconductor device 1 will be described. Fig. 2 is a flowchart showing a method of manufacturing the semiconductor device 1 according to the first embodiment. Fig. 3 is a cross-sectional view showing a step of forming the functional layer 10 on the InP substrate 15 via the buffer layer 16 and the sacrificial layer 17.

[0023] In step S101 (FIG. 2), as shown in FIG. 3, a buffer layer 16 is epitaxially grown on an InP substrate 15. Furthermore, a sacrificial layer 17 is epitaxially grown on the buffer layer 16.

[0024] The InP substrate 15 is made of InP and is a substrate on the surface of which epitaxial layers (the sacrificial layer 17 and each layer of the functional layer 10) are grown, and is also called a growth substrate.

[0025] The buffer layer 16 is made of InP and has a thickness of, for example, 100 nm. The buffer layer 16 is an intermediate layer for reducing the difference in lattice constant between the InP substrate 15 and the sacrificial layer 17. However, if the difference in lattice constant between the InP substrate 15 and the sacrificial layer 17 is small, it is possible to omit the buffer layer 16.

[0026] The sacrificial layer 17 is made of InGaAs or InP and has a thickness of, for example, 100 nm to 200 nm. The sacrificial layer 17 is a layer that is removed when the functional layer 10 is peeled off from the InP substrate 15, as will be described later.

[0027] Furthermore, a lower cladding layer 11 made of n-InP is epitaxially grown on the sacrificial layer 17, and an active layer 12 made of i-InGaAs is epitaxially grown on the lower cladding layer 11. Furthermore, an upper cladding layer 13 made of p-InP is epitaxially grown on the active layer 12, and a contact layer 14 made of p-InGaAs is epitaxially grown on the upper cladding layer 13.

[0028] As a result, the lower cladding layer 11, the active layer 12, the upper cladding layer 13, and the contact layer 14 are laminated in this order on the sacrificial layer 17, thereby forming the functional layer 10 (step S102 in FIG. 2).

[0029] 4 is a cross-sectional view showing a step of etching the functional layer 10. In step S103 (FIG. 2), as shown in FIG. 4, the functional layer 10 is patterned by etching. The etching may be dry etching or wet etching.

[0030] The etching is performed to a depth that reaches the buffer layer 16. Note that, in the example shown in Fig. 4, the etching is performed so that the area of ​​the sacrificial layer 17 (more specifically, the area in the direction perpendicular to the stacking direction) is larger than the area of ​​the functional layer 10, but the etching may be performed so that the area of ​​the sacrificial layer 17 and the area of ​​the functional layer 10 are the same.

[0031] 5 is a cross-sectional view showing a step of forming the protective film 31. In step S104 (FIG. 2), as shown in FIG. 5, the protective film 31 is formed so as to cover the functional layer 10. The protective film 31 is made of, for example, Al ２ O ３ (aluminum oxide), Si ３ N ４ (silicon nitride) or SiO ２ The film formation method is, for example, ALD (atomic layer deposition).

[0032] The protective film 31 has a first portion 31a that covers the surface of the functional layer 10 (i.e., the surface of the contact layer 14), a second portion 31b that covers the side surface of the functional layer 10, and a third portion 31c that covers the surface of the sacrificial layer 17. The protective film 31 protects the functional layer 10 during a step of removing the sacrificial layer 17 (FIG. 7) described below and other steps.

[0033] 6 is a cross-sectional view showing a process of forming the stamp 32. In step S105 (FIG. 2), as shown in FIG. 6, the stamp 32 is formed as a transfer holder on the protective film 31. The stamp 32 is made of, for example, a tacky or adhesive elastomer, rubber, resin, or the like. The stamp 32 is bonded to the first portion 31a of the protective film 31.

[0034] 7 is a cross-sectional view showing the step of peeling off the functional layer 10. In step S106 (FIG. 2), the sacrificial layer 17 (FIG. 6) is removed. The sacrificial layer 17 is removed by wet etching using, for example, hydrochloric acid, phosphoric acid, or the like. By removing the sacrificial layer 17, the functional layer 10 held by the stamp 32 is peeled off from the InP substrate 15.

[0035] Separately from steps S101 to S106, the base substrate 20 is manufactured. Fig. 8 is a cross-sectional view showing the process of forming an organic film 23 above the Si substrate 21. In step S107 (Fig. 2), as shown in Fig. 8, the organic film 23 is formed on the native oxide film 22 formed on the main surface 21a of the Si substrate 21. The organic film 23 is formed by, for example, spin coating.

[0036] As described above, the native oxide film 22 is formed on the main surface 21a of the Si substrate 21 by reaction with oxygen in the air. ２The film has a thickness of less than 10 nm.

[0037] The organic film 23 is formed from PI, PA, silicone resin, or acrylic resin, with PI being the most desirable due to its high heat and chemical resistance. PI is also advantageous in that it has a small refractive index difference with the lower cladding layer 11 (InP) formed on the organic film 23. This results in the formation of a base substrate 20 consisting of the Si substrate 21, the native oxide film 22, and the organic film 23.

[0038] Note that step S107 may be performed in parallel with steps S101 to S106, or may be performed before or after steps S101 to S106.

[0039] 9 is a cross-sectional view showing a step of transferring the functional layer 10 to the base substrate 20. In step S108 (FIG. 2), the functional layer 10 held by the stamp 32 is transferred to the base substrate 20, as shown in FIG.

[0040] More specifically, the lower surface of the lower cladding layer 11 of the functional layer 10 is brought into contact with the surface of the organic film 23 of the base substrate 20, and a predetermined amount of pressure and heat is applied, thereby bonding the lower cladding layer 11 and the organic film 23 by intermolecular forces.

[0041] After the functional layer 10 is transferred to the base substrate 20, the stamp 32 is peeled off from the functional layer 10. Because the stamp 32 is attached to the functional layer 10 by tackiness or adhesiveness, it can be easily peeled off by applying force to pull the stamp 32 away from the base substrate 20.

[0042] 10A is a cross-sectional view showing the step of removing the protective film 31 (FIG. 9). In step S109 (FIG. 2), the protective film 31 covering the functional layer 10 is removed. The protective film 31 is removed by wet etching using hydrofluoric acid. By removing the protective film 31, an electronic structure in which the functional layer 10 is bonded onto the base substrate 20 is obtained.

[0043] Here, the native oxide film 22 on the Si substrate 21 has the property of being removed by hydrofluoric acid, but since the organic film 23 covers the native oxide film 22, the native oxide film 22 is prevented from being corroded by hydrofluoric acid, and therefore the bonding state between the base substrate 20 and the functional layer 10 is not impaired.

[0044] 10B is a cross-sectional view showing the process of forming the electrodes 18 and 19. In step S110 (FIG. 2), as shown in FIG. 10B, the electrode 18 is formed on the surface of the contact layer 14 of the functional layer 10, and the electrode 19 is formed on the organic film 23 at a position where it contacts the lower cladding layer 11. The electrodes 18 and 19 are formed of, for example, Pt (platinum). Furthermore, wiring layers (not shown) are formed to be connected to the electrodes 18 and 19, respectively.

[0045] 1, when light L having a wavelength of 900 nm or more is incident on the back surface 21 b of the Si substrate 21, the light passes through the Si substrate 21, the native oxide film 22, and the organic film 23 to reach the functional layer 10, where it is received and converted into an electrical signal, which is then output from the electrodes 18 and 19.

[0046] <Configuration and Function of Organic Film> Next, the configuration and function of the organic film 23 will be described. In the manufacturing process of the semiconductor device 1 having the Si substrate 21, as described with reference to FIG. 8, a native oxide film 22 (SiO ２ ) is formed.

[0047] Therefore, if the functional layer 10 is bonded to the natural oxide film 22 of the Si substrate 21 without providing an organic film 23, the natural oxide film 22 may be eroded by an etching solution such as hydrofluoric acid during the etching process after bonding (e.g., the process of removing the protective film 31), and the bonding strength between the natural oxide film 22 and the functional layer 10 may be reduced.

[0048] In this embodiment, the native oxide film 22 on the Si substrate 21 is covered with a chemical-resistant organic film 23. Therefore, the native oxide film 22 is not eroded by an etching solution. That is, the bonding strength between the organic film 23 and the functional layer 10 is maintained, and peeling of the functional layer 10 from the organic film 23 is prevented.

[0049] Here, the bonding strength between the organic film 23 and the functional layer 10 depends on the film thickness of the organic film 23. If the bonding strength is insufficient, the functional layer 10 may be displaced on the organic film 23 or peeled off.

[0050] A scratch test was performed to examine the bonding strength between the organic film 23 and the functional layer 10. A plurality of test pieces were prepared by bonding the functional layer 10 to organic films 23 of different thicknesses on the Si substrate 21.

[0051] Specifically, organic films 23 (polyimide films) with thicknesses of 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, and 11 nm were formed on the surface of a native oxide film 22 on a Si substrate 21. A functional layer 10 having a square planar shape and 80 μm sides was bonded to the surface of each organic film 23.

[0052] Then, using a scratch tester, the side surface of the functional layer 10 of each test piece was pressed with a constant pressure by an indenter, and it was observed whether the functional layer 10 slipped on the organic film 23 or not.

[0053] If the functional layer 10 slipped on the organic film 23, the bonding strength was judged to be insufficient (B: poor). If the pressed functional layer 10 did not slip on the organic film 23, the bonding strength was judged to be sufficient (G: good). The results are shown in Table 1 below.

[0054]

[0055] The scratch test results showed that when the thickness of the organic film 23 was 9 nm or less, the functional layer 10 pressed by the indenter slipped on the organic film 23, resulting in insufficient bonding strength. In contrast, when the thickness of the organic film 23 was 10 nm or more, the functional layer 10 pressed by the indenter did not slip on the organic film 23, resulting in sufficient bonding strength.

[0056] 11A and 11B are diagrams showing the state of the functional layer 10 on the surface of the 5-nm-thick organic film 23 before and after being pressed by the indenter 40. As shown in 11A and 11B, when the thickness of the organic film 23 is 5 nm, the functional layer 10 pressed by the indenter 40 slips, indicating insufficient bonding strength.

[0057] 12A and 12B are diagrams showing the state of the functional layer 10 on the surface of the 11-nm-thick organic film 23 before and after being pressed by the indenter 40. As shown in 12A and 12B, when the organic film 23 has a thickness of 11 nm, the functional layer 10 does not slip even when the indenter 40 applies a force strong enough to damage the functional layer 10, and sufficient bonding strength is obtained.

[0058] Note that the examples shown in Figures 11(A), (B) and Figures 12(A), (B) are representative examples, and as shown in Table 1, if the film thickness of the organic film 23 is 10 nm or more, no slippage of the functional layer 10 was observed even when pressed with the indenter 40, and sufficient bonding strength was obtained.

[0059] From this result, it can be seen that in order to obtain a sufficient bonding strength between the organic film 23 and the functional layer 10, it is desirable that the thickness of the organic film 23 be 10 nm or more.

[0060] Next, we will explain the light transmission characteristics of the organic film 23. In the semiconductor device 1, light incident on the back surface 21b of the Si substrate 21 passes through the Si substrate 21, the native oxide film 22, and the organic film 23 to reach the functional layer 10, so reducing the loss of light is an issue.

[0061] In particular, if the difference in refractive index between the organic film 23 and the lower cladding layer 11 is large, light loss is likely to occur due to reflection and refraction of light at the interface between the organic film 23 and the lower cladding layer 11 .

[0062] In contrast to this, in the present embodiment, the lower cladding layer 11 of the functional layer 10 that is in contact with the organic film 23 is formed of InP. InP has a smaller difference in refractive index from the organic film 23 than other semiconductor materials (e.g., InGaAs, InGaAsP) that can receive or emit light with a wavelength of 900 nm or more.

[0063] For example, the refractive index of the organic film 23 formed from PI is 1.61, whereas the refractive index of InP is 3.16, the refractive index of InGaAs is 3.5, and the refractive index of InGaAsP is 3.35. Note that these refractive index values ​​are values ​​when the wavelength λ of light is 1550 nm.

[0064] By forming the lower cladding layer 11 from InP, the difference in refractive index between the lower cladding layer 11 and the organic film 23 is smaller than when the lower cladding layer 11 is formed from InGaAs or InGaAsP. Therefore, reflection and refraction of light at the interface between the organic film 23 and the lower cladding layer 11 can be suppressed, and light loss can be reduced.

[0065] Furthermore, PI has a particularly high refractive index among organic materials, so if the organic film 23 is made of PI and the lower cladding layer 11 is made of InP, the difference in refractive index between the organic film 23 and the lower cladding layer 11 can be minimized, thereby enhancing the effect of reducing light loss.

[0066] The native oxide film 22 has a thickness of less than 10 nm (generally 3 nm or less), which is thinner than the organic film 23. ２ Since the refractive index (1.60 to 1.63) of the organic film 23 is approximately equal to the refractive index (1.61) of the organic film 23, the optical characteristics can be ignored.

[0067] As explained with reference to Table 1, it is desirable that the thickness of the organic film 23 be 10 nm or more in order to obtain sufficient bonding strength between the functional layer 10 and the organic film 23. However, if the organic film 23 is too thick, thin film interference may occur depending on the angle of incidence on the organic film 23, which may increase loss.

[0068] That is, when light is incident on the interface between the organic film 23 and the lower cladding layer 11, and on the interface between the organic film 23 and the Si substrate 21, light having a large angle of incidence relative to the normal direction of each interface may not be able to pass through the organic film 23.

[0069] Therefore, using Snell's law and Fresnel's law, the relationship between the film thickness of the organic film 23 and the light transmittance was analyzed. In the analysis, the refractive index of the organic film 23 (PI) was set to 1.61, the refractive index of the lower cladding layer 11 (InP) to 3.16, and the refractive index of the Si substrate 21 to 3.47. Four wavelengths of light were used: 900 nm, 1000 nm, 1300 nm, and 1550 nm.

[0070] 13 is a graph showing the relationship between the film thickness and light transmittance of the organic film 23, as determined by analysis. As shown in Fig. 13, for light of any wavelength between 900 nm and 1550 nm, the thicker the film thickness of the organic film 23, the lower the transmittance of the organic film 23. Furthermore, the longer the wavelength of the light, the higher the transmittance at the same film thickness.

[0071] From FIG. 13, it can be seen that when the thickness of the organic film 23 is 85 nm or less, the transmittance of light with a wavelength λ of 900 nm is 70% or more, and the transmittance of light with a wavelength λ of more than 900 nm is even higher.

[0072] Furthermore, when the thickness of the organic film 23 is 40 nm or less, the transmittance of light with a wavelength λ of 900 nm is 90% or more, and the transmittance of light with a wavelength λ of more than 900 nm is even higher.

[0073] That is, in order to reduce the loss of light passing through the organic film 23, it is desirable that the film thickness T of the organic film 23 be 85 nm or less (i.e., satisfying T≦85 nm), and it is even more desirable that it be 40 nm or less (i.e., satisfying T≦40 nm).

[0074] Here, the case where the refractive index n of the organic film 23 (PI) is 1.61 has been described, but the organic film 23 is not limited to PI and may be PA, silicone resin, or acrylic resin. Therefore, the refractive index of the organic film 23 is set to n, and the relationship between the film thickness and transmittance of the organic film 23 shown in FIG. 13 is generalized.

[0075] The product (T×n) of the thickness T and the refractive index n of the organic film 23 can be considered to be the optical distance when light passes through the organic film 23. If the product of the thickness T and the refractive index n is 10% or less of the wavelength λ of the light, the light can pass through the organic film 23 even when the angle of incidence of the light on the organic film 23 is large. In other words, it is desirable that the thickness T and the refractive index n of the organic film 23 satisfy T×n≦λ×0.1.

[0076] Therefore, when the refractive index of the organic film 23 is n and the wavelength of light received or emitted by the functional layer 10 is λ, light loss can be reduced if the thickness T of the organic film 23 is in the range of T≦λ×0.1 / n. In this case, the transmittance of light with a wavelength λ of 900 nm or more can be made 70% or more.

[0077] Furthermore, if the thickness T of the organic film 23 is in the range of T≦λ×0.07 / n, the effect of reducing light loss can be further enhanced. In this case, the transmittance of light with a wavelength λ of 900 nm or more can be made 90% or more.

[0078] To summarize the above, in order to reduce light loss and ensure the bonding strength between the organic film 23 and the functional layer 10, it is desirable that the thickness T of the organic film 23 be in the range of 10 nm≦T≦λ×0.1 / n (more preferably, 10 nm≦T≦λ×0.07 / n).

[0079] Furthermore, when the organic film 23 is PI (refractive index 1.61), in order to reduce light loss and ensure the bonding strength between the organic film 23 and the functional layer 10, it is desirable that the thickness T of the organic film 23 be in the range of 10 nm≦T≦85 nm, and it is even more desirable that it be in the range of 10 nm≦T≦40 nm.

[0080] Here, the organic film 23 is formed on the native oxide film 22, but the native oxide film 22 is not necessarily required, and it is sufficient that the organic film 23 is formed above the Si substrate 21. "Formed above the Si substrate 21" means that another layer may be interposed between the Si substrate 21 and the organic film 23. The other layer may be the native oxide film 22 or another layer.

[0081] Although the functional layer 10 has been described here as having an n-InP layer (lower cladding layer 11), an i-InGaAs layer (active layer 12), and a p-InP layer (upper cladding layer 13), the functional layer 10 may have another laminated structure as long as the layer (surface) in contact with the organic film 23 is made of InP, or the functional layer may be a single-layer functional layer made of InP only. That is, it is sufficient that at least the surface of the functional layer 10 that is bonded to the organic film 23 is made of InP.

[0082] Here, the role of the organic film 23 has been described as protecting the native oxide film 22 from the etching solution that removes the protective film 31. However, the role of the organic film 23 is not limited to protecting the native oxide film 22 from the etching solution that removes the protective film 31. For example, even if there is a process other than the process of removing the protective film 31, the organic film 23 only needs to have the role of protecting the native oxide film 22 from chemicals used in the other process.

[0083] As mentioned above, PI is the most desirable material for the organic film 23, but PA, silicone resin, or acrylic resin can also be used, as the difference in refractive index between them and InP is relatively small, and therefore it is possible to obtain the effect of reducing light loss.

[0084] Effect of First Embodiment As described above, the semiconductor device 1 of the first embodiment includes the Si substrate 21, the organic film 23 formed above the Si substrate 21, and the functional layer 10 formed on the organic film 23 and serving as a semiconductor layer that receives or emits light. Of the functional layer 10, a surface that is bonded to the organic film 23 is made of InP. As an example, of the functional layer 10, a layer (e.g., the lower cladding layer 11) that is bonded to the organic film 23 is made of InP.

[0085] In this way, the surface of the functional layer 10 that is bonded to the organic film 23 is made of InP, and the difference in refractive index between InP and the organic film 23 is small, so that light loss can be reduced.

[0086] Furthermore, if the wavelength of light received or emitted by the functional layer 10 is λ and the refractive index of the organic film 23 is n, the thickness T of the organic film 23 can satisfy T≦λ×0.1 / n, thereby increasing the light transmittance in the organic film 23 and particularly reducing light loss.

[0087] Furthermore, by setting the film thickness T of the organic film 23 to 85 nm or less (more preferably 40 nm or less), when the organic film 23 is formed of PI, the light transmittance of the organic film 23 can be increased and light loss can be reduced.

[0088] Furthermore, by making the film thickness T of the organic film 23 10 nm or more, sufficient bonding strength between the organic film 23 and the functional layer 10 can be obtained, and peeling of the functional layer 10 from the organic film 23 can be prevented.

[0089] Furthermore, by forming the organic film 23 from PI, the high heat resistance and chemical resistance of PI can prevent poor bonding between the functional layer 10 and the organic film 23 in each process after bonding the functional layer 10 to the organic film 23, thereby improving the reliability of the semiconductor device 1.

[0090] In addition, a SiO film having a thickness smaller than that of the organic film 23 is formed on the Si substrate 21. ２ A native oxide film 22, which is a film, is formed, and an organic film 23 is formed on the native oxide film 22. The native oxide film 22 may be removed by an etching solution in an etching process (e.g., a process for removing the protective film 31) after bonding the functional layer 10 to the organic film 23. However, since the organic film 23 is formed on the native oxide film 22, the native oxide film 22 can be protected. This makes it possible to prevent peeling of the functional layer 10 due to removal of the native oxide film 22.

[0091] Furthermore, the functional layer 10 is constructed by sandwiching a photoelectric conversion layer (e.g., an active layer 12) made of InGaAs between a lower cladding layer 11 made of InP and an upper cladding layer 13 made of InP, which makes it possible to apply the functional layer 10 to, for example, photodiodes, semiconductor lasers, etc. that can receive or emit light with a wavelength of 900 nm or more.

[0092] The method for manufacturing semiconductor device 1 of this embodiment includes the steps of forming functional layer 10 on InP substrate 15 via sacrificial layer 17, peeling functional layer 10 from InP substrate 15 by removing sacrificial layer 17, and bonding functional layer 10 peeled from InP substrate 15 to organic film 23 formed above Si substrate 21. Therefore, functional layer 10 epitaxially grown on InP substrate 15 can be transferred to light-transmitting Si substrate 21, thereby obtaining semiconductor device 1.

[0093] Although the preferred embodiments have been specifically described above, the present disclosure is not limited to the above-described embodiments, and various improvements and modifications can be made.

[0094] REFERENCE SIGNS LIST 1 semiconductor device, 10 functional layer (semiconductor layer), 11 lower cladding layer (InP layer), 12 active layer (photoelectric conversion layer, InGaAs layer), 13 upper cladding layer (InP layer), 14 contact layer, 15 InP substrate (growth substrate), 16 buffer layer, 17 sacrificial layer, 18, 19 electrode, 20 base substrate, 21 Si substrate (transfer substrate), 21a main surface, 21b back surface, 22 native oxide film (SiO ２ film), 23 organic film (PI film), 31 protective film, 32 stamp, 40 indenter.

Claims

1. A semiconductor device comprising: a Si substrate; an organic film formed above said Si substrate; and a semiconductor layer formed on said organic film for receiving or emitting light, wherein the surface of said semiconductor layer that is bonded to said organic film is made of InP.

2. The semiconductor device according to claim 1, wherein the thickness T (nm) of the organic film satisfies the following relationship: T≦λ×0.1 / n, where λ (nm) is the wavelength of light received or emitted by the semiconductor layer and n is the refractive index of the organic film.

3. The semiconductor device according to claim 1 or 2, wherein the thickness T of the organic film is 85 nm or less.

4. The semiconductor device according to any one of claims 1 to 3, wherein the thickness T of the organic film is 40 nm or less.

5. The semiconductor device according to any one of claims 1 to 4, wherein the thickness T of the organic film is 10 nm or more.

6. The semiconductor device according to any one of claims 1 to 5, wherein the organic film is formed of polyimide.

7. A SiO film having a thickness smaller than that of the organic film is formed on the Si substrate. ２ The organic film has a SiO ２ The semiconductor device according to any one of claims 1 to 6, which is formed on a film.

8. A semiconductor device according to any one of claims 1 to 7, characterized in that the semiconductor layer is constructed by sandwiching a photoelectric conversion layer made of InGaAs between a lower cladding layer made of InP and an upper cladding layer made of InP, and the lower cladding layer is bonded to the organic film.

9. The semiconductor device according to any one of claims 1 to 8, characterized in that the semiconductor layer receives or emits light having a wavelength λ of 900 nm or more, and the Si substrate transmits light received by or emitted from the semiconductor layer.

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