NITRIDE SEMICONDUCTOR, SEMICONDUCTOR DEVICE, AND METHOD FOR MANUFACTURING NITRIDE SEMICONDUCTOR

Abstract

To provide a nitride semiconductor, a semiconductor device, and a method for manufacturing the nitride semiconductor capable of suppressing warpage.SOLUTION: According to an embodiment, a nitride semiconductor includes a substrate, a nitride member, and an intermediate region between the substrate and the nitride member. The nitride member includes a first nitride region including Alx1Ga1-x1N (0<x1≤1) and a second nitride region including Alx2Ga1-x2N (0≤x2<1, x2<x1). The first nitride region is between the intermediate region and the second nitride region. The intermediate region contains nitrogen and carbon. The concentration of carbon in the intermediate region is between 1.5×1019 / cm3 and 6×1020 / cm3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a nitride semiconductor, a semiconductor device, and a method for manufacturing a nitride semiconductor.

Background Art

[0002] For example, a semiconductor device is manufactured using a wafer including a nitride semiconductor. Suppression of warpage is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a nitride semiconductor, a semiconductor device, and a method for manufacturing a nitride semiconductor capable of suppressing warpage.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, a nitride semiconductor includes a substrate, a nitride member, and an intermediate region provided between the substrate and the nitride member. The nitride member includes a first nitride region containing Al x1 Ga 1-x1 N (0 <x1 ≦ 1), and a second nitride region containing Al x2 Ga 1-x2 N (0 ≦ x2 <1, x2 <x1). The first nitride region is between the intermediate region and the second nitride region. The intermediate region contains nitrogen and carbon. The concentration of carbon in the intermediate region is 1.5 × 10 19 / cm 3 or more and 6 × 10 20 / cm 3 or less.

Brief Description of the Drawings

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view illustrating the nitride semiconductor according to the first embodiment. [Diagram 2] FIG. 2 is a graph illustrating the nitride semiconductor according to the first embodiment. [Diagram 3] FIG. 3 is a graph illustrating the nitride semiconductor according to the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view illustrating the nitride semiconductor according to the first embodiment. As shown in FIG. [Diagram 5] FIG. 5 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. [Figure 6] FIG. 6 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. [Figure 7] FIG. 7 is a flowchart illustrating the method for manufacturing a nitride semiconductor according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

[0008] (First embodiment) FIG. 1 is a schematic cross-sectional view illustrating the nitride semiconductor according to the first embodiment. 1, the nitride semiconductor 110 according to the embodiment includes a base body 18s, a nitride member 10M, and an intermediate region 11M. The intermediate region 11M is located between the base body 18s and the nitride member 10M. The wafer 210 includes the nitride semiconductor 110.

[0009] The substrate 18s contains, for example, silicon. The substrate 18s is, for example, a silicon substrate.

[0010] The nitride member 10M includes a first nitride region 11 and a second nitride region 12. The first nitride region 11 is located between the intermediate region 11M and the second nitride region 12.

[0011] The nitride member 10M may include a third nitride region 13, a fourth nitride region 14, a fifth nitride region 15, etc. The fourth nitride region 14 and the fifth nitride region 15 correspond to functional layers. The third nitride region 13, the fourth nitride region 14, and the fifth nitride region 15 are provided as required and may be omitted. At least any one of the third nitride region 13, the fourth nitride region 14, and the fifth nitride region 15 may be regarded as being included in the second nitride region 12.

[0012] The first nitride region 11 contains Al x1 Ga 1-x1 N(0 < x1 ≤ 1). The composition ratio x1 of Al in the first nitride region 11 is, for example, 0.35 or more and 1 or less. In one example, the first nitride region 11 contains AlN.

[0013] The second nitride region 12 contains Al x2 Ga 1-x2 N(0 ≤ x2 < 1, x2 < x1). For example, the second nitride region 12 contains AlGaN or GaN.

[0014] The direction from the first nitride region 11 to the second nitride region 12 is defined as the first direction. The first direction is defined as the Z-axis direction. One direction perpendicular to the Z-axis direction is defined as the X-axis direction. The direction perpendicular to the Z-axis direction and the X-axis direction is defined as the Y-axis direction.

[0015] The substrate 18s, the intermediate region 11M, the first nitride region 11, and the second nitride region 12 are in a layered form along the X-Y plane.

[0016] For example, the intermediate region 11M contacts the substrate 18s. For example, the intermediate region 11M contacts the first nitride region 11. For example, the first nitride region 11 contacts the second nitride region 12.

[0017] For example, at least a portion of the intermediate region 11M may include aluminum. For example, at least a portion of the intermediate region 11M may include silicon.

[0018] The intermediate region 11M contains nitrogen and carbon. The concentration of carbon in the intermediate region 11M is 1.5×10 19 / cm 3 More than 6×10 20 / cm 3 The carbon concentration in the intermediate region 11M is 3×10 19 / cm 3 More than 4×10 20 / cm 3 The following is also fine.

[0019] It has been found that the provision of such intermediate region 11M makes it possible to suppress warpage in the nitride semiconductor 110 (for example, the wafer 210).

[0020] FIG. 2 is a graph illustrating the nitride semiconductor according to the first embodiment. Fig. 2 illustrates the results of a secondary ion mass spectrometry (SIMS) analysis of the nitride semiconductor 110. In Fig. 2, the horizontal axis represents the position pZ in the Z-axis direction. The left vertical axis in Fig. 2 represents the carbon concentration C(C) or the silicon concentration C(Si). The right vertical axis in Fig. 2 represents the secondary ion intensity Int_Al of Al or the secondary ion intensity Int_N of N.

[0021] As shown in FIG. 2, an intermediate region 11M is provided between the substrate 18s and the first nitride region 11. The intermediate region 11M includes carbon. The intermediate region 11M includes nitrogen. In this example, the intermediate region 11M includes aluminum and silicon. The substrate 18s is substantially free of nitrogen. The intermediate region 11M, the first nitride region 11, and the second nitride region 12 include nitrogen.

[0022] As described below, such an intermediate region 11M is obtained by supplying a first gas containing carbon to the substrate 18s, then stopping the supply of the first gas containing carbon, supplying a second gas containing nitrogen, and then forming the first nitride region 11 and the second nitride region 12.

[0023] The carbon concentration C(C) in the intermediate region 11M can be controlled, for example, by the supply amount of a first gas containing carbon. The carbon concentration C(C) in the intermediate region 11M can also be controlled, for example, by the temperature of the heat treatment of the base 18s. When the supply amount of the first gas is large, the carbon concentration C(C) in the intermediate region 11M becomes high. When the heat treatment temperature is low, the carbon concentration C(C) in the intermediate region 11M becomes high.

[0024] Below, an example of the experimental results regarding the change in warpage when the carbon concentration C(C) is changed will be described.

[0025] FIG. 3 is a graph illustrating the nitride semiconductor according to the first embodiment. The horizontal axis of FIG. 3 is the carbon concentration CC1 in the intermediate region 11M. The vertical axis of FIG. 3 is the amount of warpage W1 of the wafer 210. The amount of warpage W1 is normalized based on the amount of warpage in the case where the intermediate region 11M is not provided (first reference example). In the first reference example, the first nitride region 11 contacts the base body 18s. In this experimental example, the amount of warpage in the first reference example is about 170 μm.

[0026] As shown in Fig. 3, the carbon concentration CC1 in the intermediate region 11M is 1.5 × 10 19 / cm 3 More than 6×10 20 / cm 3 The amount of warping W1 is small when the concentration CC1 is 1.5×10 19 / cm 3 When the concentration CC1 is less than 6×10, the warpage W1 is large. 20 / cm 3 If it exceeds this value, the amount of warpage W1 is large.

[0027] In the first reference example, the warpage is caused by, for example, stress occurring between the base body 18s and the nitride member 10M. The stress is caused by, for example, the difference in thermal expansion coefficient between the base body 18s and the nitride member 10M.

[0028] The carbon concentration CC1 in the intermediate region 11M is 1.5×10 19 / cm 3 More than 6×10 20 / cm 3 Warping can be suppressed in the following cases. It is believed that the stress is alleviated by providing the intermediate region 11M having such carbon concentration CC1 between the base body 18s and the nitride member 10M. This makes it possible to suppress warping.

[0029] As shown in FIG. 3, the characteristic between the carbon concentration CC1 in the intermediate region 11M and the warpage amount W1 is critical. 19 / cm 3 The amount of warping W1 changes rapidly near the concentration CC1 of about 6×10 20 / cm 3 As shown in FIG. 3, when the carbon concentration CC1 in the intermediate region 11M is 3×10 19 / cm 3 More than 4×10 20 / cm 3 The amount of warpage W1 is smaller when:

[0030] 2, for example, the first nitride region 11 is substantially free of carbon. Alternatively, the carbon concentration C(C) in the first nitride region 11 is lower than the carbon concentration C(C) in the intermediate region 11M. When the carbon concentration C(C) in the first nitride region 11 is low, for example, the defect density tends to be low in the nitride member 10M. For example, the strain applied to the second nitride region 12 becomes large. This reduces the defects.

[0031] 2, for example, the second nitride region 12 contains carbon. The concentration C(C) of carbon in the second nitride region 12 is higher than the concentration C(C) of carbon in the first nitride region 11. When the second nitride region 12 contains carbon, for example, a low dislocation density is easily obtained in the nitride member 10M. For example, dislocations are easily bent in the second nitride region 12 containing carbon. As a result, dislocations extending above the second nitride region 12 along the first direction (Z-axis direction) are reduced.

[0032] For example, the carbon concentration C(C) in the second nitride region 12 is lower than the carbon concentration C(C) in the intermediate region 11M. When the carbon concentration C(C) in the second nitride region 12 is not excessively high, for example, the strain applied to the second nitride region 12 becomes large. For example, when the second nitride region 12 is formed, the strain applied to the second nitride region 12 becomes difficult to relax. This makes it easier to control warpage.

[0033] 2, for example, the silicon concentration C(Si) in the first nitride region 11 is lower than the carbon concentration C(C) in the first nitride region 11. For example, the ratio of the silicon concentration C(Si) in the first nitride region 11 to the carbon concentration C(C) in the first nitride region 11 is 0.0001 or more and 0.01 or less. When the silicon concentration C(Si) in the first nitride region 11 is low, for example, when the second nitride region 12 is formed, the strain applied to the second nitride region 12 is less likely to be relaxed. This makes it easier to control the warpage.

[0034] For example, the silicon concentration C(Si) in the second nitride region 12 is lower than the carbon concentration C(C) in the second nitride region 12. For example, the ratio of the silicon concentration C(Si) in the second nitride region 12 to the carbon concentration C(C) in the second nitride region 12 is 0.0001 or more and 0.1 or less. When the silicon concentration C(Si) in the second nitride region 12 is low, for example, the strain applied to the second nitride region 12 is less likely to be relaxed. This makes it easier to control the warpage.

[0035] In the embodiment, the thickness of the intermediate region 11M (intermediate region thickness tm1 (see FIG. 1)) is, for example, not less than 0.5 nm and not more than 100 nm.

[0036] The thickness of the first nitride region 11 (first nitride region thickness tr1 (see FIG. 1)) is, for example, not less than 5 nm and not more than 500 nm.

[0037] The thickness of the second nitride region 12 (second nitride region thickness tr2 (see FIG. 1)) is, for example, not less than 50 nm and not more than 200 nm.

[0038] As shown in FIG. 1, the nitride member 10M may include a third nitride region 13. The third nitride region 13 may be, for example, Al x3 Ga 1-x3 N (0≦x3≦1). The third nitride region 13 includes, for example, AlGaN or GaN. As described later, the third nitride region 13 may have, for example, a stacked structure. The thickness of the third nitride region 13 (third nitride region thickness tr3 (see FIG. 1)) is, for example, 100 nm or more and 8000 nm or less.

[0039] As shown in FIG. 1, as previously described, the nitride member 10M may include a fourth nitride region 14 and a fifth nitride region 15. The fourth nitride region 14 is made of Al x4 Ga 1-x4 N (0≦x4<1). The Al composition ratio x4 in the fourth nitride region 14 is, for example, 0 or more and 0.5 or less. The fourth nitride region 14 includes, for example, GaN. The Al composition ratio x4 in the fourth nitride region 14 is lower than the Al composition ratio in the third nitride region 13. The thickness of the fourth nitride region 14 (fourth nitride region thickness tr4 (see FIG. 1)) is, for example, 50 nm or more and 5000 nm or less.

[0040] As shown in FIG. 1, the fourth nitride region 14 may include a first film region 14a and a second film region 14b. The first film region 14a is between the third nitride region 13 and the second film region 14b. The first film region 14a contains carbon. The second film region 14b does not contain carbon. Or, the concentration of carbon in the second film region 14b is lower than the concentration of carbon in the first film region 14a. By providing the first film region 14a containing carbon, for example, it becomes easier to obtain a low dislocation density. The second film region 14b with a low carbon concentration makes it easier to obtain, for example, a high electron mobility. The thickness of the first film region 14a (the first film region thickness tr4a (see FIG. 1)) is, for example, 100 nm or more and 3000 nm or less. The thickness of the second film region 14b (the second film region thickness tr4b (see FIG. 1)) is, for example, 50 nm or more and 2000 nm or less.

[0041] The fifth nitride region 15 contains Al x5 Ga 1-x5 N (0 < x5 ≦ 1, x4 < x5). The composition ratio x5 of Al in the fifth nitride region 15 is, for example, 0.05 or more and 0.35 or less. The fifth nitride region 15 is, for example, AlGaN. The thickness of the fifth nitride region 15 (the fifth nitride region thickness tr5 (see FIG. 1)) is, for example, 15 nm or more and 50 nm or less. The second nitride region 12 is between the first nitride region 11 and the fifth nitride region 15. The third nitride region 13 is between the second nitride region 12 and the fifth nitride region 15. The fourth nitride region 14 is between the third nitride region 13 and the fifth nitride region 15.

[0042] For example, a carrier region is formed in a portion of the fourth nitride region 14 facing the fifth nitride region 15. The carrier region is, for example, a two-dimensional electron gas. In a semiconductor device based on the nitride semiconductor 110, the carrier region is used for the operation of the semiconductor device.

[0043] The nitride member 10M is formed, for example, by using a source gas containing a group III element (Al or Ga) and a source gas containing a group V element (N) by, for example, the MOCVD (metal organic chemical vapor deposition) method or the like.

[0044] FIG. 4 is a schematic cross-sectional view illustrating a nitride semiconductor according to the first embodiment. As shown in FIG. 4, in the nitride semiconductor 111 and the wafer 211 according to the embodiment, the third nitride region 13 has a stacked structure.

[0045] For example, the third nitride region 13 includes a plurality of first regions 13a and a plurality of second regions 13b. In the first direction (Z-axis direction) from the first nitride region 11 to the second nitride region 12, one of the plurality of first regions 13a is between one of the plurality of second regions 13b and another one of the plurality of second regions 13b. The above-mentioned one of the plurality of second regions 13b is between the above-mentioned one of the plurality of first regions 13a and another one of the plurality of first regions 13a. For example, the first region 13a and the second region 13b are alternately provided along the Z-axis direction.

[0046] The first region 13a contains Al y1 Ga 1-y1 N (0 < y1 ≤ 1). The second region 13b contains Al y2 Ga 1-y2 N (0 ≤ y2 < y1).

[0047] The Al composition ratio (composition ratio y1) in the first region 13a is, for example, 0.75 or more and 1 or less. In one example, the first region 13a is AlN.

[0048] The Al composition ratio (composition ratio y2) in the second region 13b is, for example, 0.06 or more and 0.3 or less. In one example, the second region 13b is Al 0.13 Ga 0.87 N.

[0049] In one example, the composition ratio y1 is less than or equal to the composition ratio x1. In one example, the composition ratio y2 is higher than the composition ratio x2.

[0050] For example, one of the multiple first regions 13a may be in contact with the second nitride region 12. For example, one of the multiple second regions 13b may be in contact with the second nitride region 12. For example, one of the multiple first regions 13a may be in contact with the fourth nitride region 14. For example, one of the multiple second regions 13b may be in contact with the fourth nitride region 14. The multiple first regions 13a and the multiple second regions 13b may form, for example, a superlattice structure. The absolute value of the difference between the number of the multiple first regions 13a and the number of the multiple second regions 13b may be 0 or 1. The number of the multiple first regions 13a is, for example, 10 or more and 200 or less. One of the multiple first regions 13a may be considered as the second nitride region 12.

[0051] Each of the multiple first regions 13a has a first region thickness t1 along the first direction (Z-axis direction). For example, the first region thickness t1 is thinner than a second nitride region thickness tr2 along the first direction of the second nitride region 12. Each of the multiple second regions 13b has a second region thickness t2 along the first direction. For example, the second region thickness t2 is thinner than the second nitride region thickness tr2. For example, the first region thickness t1 is thinner than the second region thickness t2.

[0052] For example, a first region thickness t1 along the first direction of each of the multiple first regions 13a is thinner than a first nitride region thickness tr1 along the first direction of the first nitride region 11. A second region thickness t2 along the first direction of each of the multiple second regions 13b is thinner than the first nitride region thickness tr1.

[0053] The first region thickness t1 is, for example, 3 nm or more and 10 nm or less. In one example, the first region thickness t1 is 5 nm. The second region thickness t2 is, for example, 15 nm or more and 40 nm or less. In one example, the second region thickness t2 is 25 nm.

[0054] In the third nitride region 13 having such a structure, for example, dislocations are more likely to bend at the interface between the first region 13a and the second region 13b. A lower dislocation density is more likely to be obtained. By providing a plurality of regions with different Al composition ratios, for example, a high breakdown voltage is more likely to be obtained.

[0055] An example of a method for producing the nitride semiconductor 111 (wafer 211) will now be described.

[0056] The substrate 18s is treated by organic cleaning and acid cleaning. The substrate 18s is introduced into an MOCVD apparatus. The surface of the substrate 18s is heat-treated at 1000° C. in a hydrogen atmosphere. For example, the oxide film on the surface of the substrate 18s is removed by the heat treatment.

[0057] Thereafter, the intermediate region 11M is formed. For example, a first gas containing carbon is supplied at 580° C. This causes carbon to adhere to the surface of the substrate 18s. The first gas containing carbon contains, for example, trimethylaluminum (TMAl). The first gas containing carbon may contain, for example, a hydrocarbon gas such as acetylene or ethylene. Thereafter, the supply of the first gas containing carbon is stopped.

[0058] Then, a second gas containing nitrogen is supplied. The second gas contains, for example, ammonia (NH3). During the supply of the second gas, the temperature is changed, for example, from 580° C. to 1040° C. By supplying the second gas, an intermediate region 11M is formed.

[0059] The carbon concentration C(C) in the intermediate region 11M can be controlled, for example, by the supply amount (e.g., partial pressure) of the first gas containing carbon or the supply time of the first gas. The carbon concentration C(C) in the intermediate region 11M may be controlled by the temperature of the base 18s. For example, by increasing the supply amount of the first gas, the carbon concentration C(C) in the intermediate region 11M increases. By extending the supply time of the first gas, the carbon concentration C(C) in the intermediate region 11M increases. When the temperature of the base 18s is low, the carbon concentration C(C) in the intermediate region 11M increases. In forming the intermediate region 11M, the temperature of the base 18s when the second gas is supplied is, for example, 550°C or higher and 800°C or lower.

[0060] After the second gas is supplied, the first nitride region 11 is formed. For example, an AlN layer that becomes the first nitride region 11 is formed at 1040° C. using TMAl and NH3. The thickness of the first nitride region 11 (first nitride region thickness tr1) is, for example, 150 nm (for example, 5 nm or more and 500 nm or less). For example, the first nitride region 11 does not contain carbon. For example, the carbon concentration in the first nitride region 11 is lower than the carbon concentration in the intermediate region 11M. For example, the ratio of the carbon concentration in the first nitride region 11 to the carbon concentration in the intermediate region 11M is 0.05 or less. For example, the ratio of the carbon concentration in the first nitride region 11 to the carbon concentration in the intermediate region 11M may be 0.0001 or more. For example, the oxygen concentration in the first nitride region 11 is lower than the oxygen concentration in the intermediate region 11M. For example, the ratio of the oxygen concentration in the first nitride region 11 to the oxygen concentration in the intermediate region 11M is 0.05 or less. The ratio of the oxygen concentration in the first nitride region 11 to the oxygen concentration in the intermediate region 11M may be 0.0001 or more.

[0061] Then, the second nitride region 12 is formed. For example, TMAl, trimethylgallium (TMGa) and ammonia are used to form an AlGaN layer that will become at least a part of the second nitride region 12 at 960° C. This AlGaN layer is, for example, carbon-doped Al 0.12 Ga 0.88 N layer. The thickness of the second nitride region 12 (second nitride region thickness tr2) is, for example, 250 nm (for example, 50 nm or more and 2000 nm or less). The carbon concentration C (C) in the second nitride region 12 is, for example, 4.0×10 18 / cm 3 The oxygen concentration in the second nitride region 12 is, for example, 7.9×10 15 / cm 3For example, the carbon concentration in the second nitride region 12 is lower than the carbon concentration in the intermediate region 11M. For example, the carbon concentration in the second nitride region 12 is higher than the carbon concentration in the first nitride region 11. For example, the oxygen concentration in the second nitride region 12 is lower than the oxygen concentration in the intermediate region 11M. For example, the oxygen concentration in the second nitride region 12 is lower than the oxygen concentration in the first nitride region 11.

[0062] Thereafter, the third nitride region 13 is formed. For example, the third nitride region 13 includes a plurality of first regions 13a and a plurality of second regions 13b. For example, an AlN layer that becomes the first regions 13a is formed using TMAl and ammonia in an atmosphere containing nitrogen and hydrogen. The temperature for forming the first regions 13a is, for example, 940° C. The thickness of the first regions 13a (first region thickness t1) is, for example, 5 nm (for example, not less than 2 nm and not more than 15 nm).

[0063] On the first region 13a, TMAl, TMGa, and ammonia are used to form an Al layer which will become the second region 13b. 0.13 Ga 0.87 An N layer is formed. The temperature for forming the second region 13b is, for example, 940° C. The thickness of the second region 13b (second region thickness t2) is, for example, 25 nm (for example, 15 nm or more and 40 nm or less). Such formation of the first region 13a and the second region 13b is repeated a total of 125 times. A first region 13a is further formed on the last second region 13b. As a result, the third nitride region 13 is formed.

[0064] The carbon concentration in the third nitride region 13 is, for example, 1.5×10 19 / cm 3 (For example, 5×10 18 / cm 3 More than 9×10 19 / cm 3 The oxygen concentration in the third nitride region 13 is, for example, 3.9×10 16 / cm 3 (For example, 5×10 15 / cm 3 More than 1×1017 / cm 3 (below). For example, the carbon concentration in the third nitride region 13 is higher than the carbon concentration in the intermediate region 11M. For example, the oxygen concentration in the third nitride region 13 is higher than the oxygen concentration in the intermediate region 11M. For example, the carbon concentration in the third nitride region 13 is higher than the carbon concentration in the second nitride region 12. For example, the oxygen concentration in the third nitride region 13 is higher than the oxygen concentration in the second nitride region 12. For example, the carbon concentration in the third nitride region 13 is higher than the carbon concentration in the first nitride region 11. For example, the oxygen concentration in the third nitride region 13 is lower than the oxygen concentration in the first nitride region 11.

[0065] Thereafter, the temperature of the substrate 18s is set to, for example, 940° C., and the first film region 14a is formed in a hydrogen atmosphere using TMGa and ammonia. The first film region 14a is, for example, a GaN layer. The first film region 14a contains carbon. The thickness of the first film region 14a is, for example, 1000 nm (for example, 600 nm or more and 3000 nm or less). The carbon concentration in the first film region 14a is, for example, 3×10 19 / cm 3 (For example, 5×10 18 / cm 3 More than 9×10 19 / cm 3 (see below).

[0066] Thereafter, the temperature of the substrate 18s is set to, for example, 1040° C., and the second film region 14b is formed using TMGa and ammonia. The second film region 14b is, for example, an undoped GaN layer. The thickness of the second film region 14b is, for example, 500 nm (for example, 50 nm or more and 2000 nm or less).

[0067] Thereafter, the temperature of the substrate 18s is set to, for example, 1020° C., and the fifth nitride region 15 is formed using TMGa, TMAl, and ammonia. The fifth nitride region 15 is, for example, undoped Al 0.2 Ga 0.8The fifth nitride region 15 is an N layer. The thickness of the fifth nitride region 15 is, for example, 30 nm (for example, not less than 15 nm and not more than 50 nm).

[0068] The first film region 14a, the second film region 14b and the fifth nitride region 15 become part of the functional layer.

[0069] Second embodiment The second embodiment relates to a semiconductor device. FIG. 5 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. As shown in FIG. 5, the semiconductor device 120 according to the embodiment includes the nitride semiconductor according to the first embodiment (in this example, the nitride semiconductor 110), a first electrode 51, a second electrode 52, a third electrode 53, and an insulating member 61.

[0070] The direction from the first electrode 51 to the second electrode 52 is along a second direction intersecting the first direction (Z-axis direction). The second direction is, for example, the X-axis direction. The position of the third electrode 53 in the second direction is between the position of the first electrode 51 in the second direction and the position of the second electrode 52 in the second direction.

[0071] The nitride member 10M includes first to fifth nitride regions 11 to 15. The fourth nitride region 14 includes a first partial region 10a, a second partial region 10b, a third partial region 10c, a fourth partial region 10d, and a fifth partial region 10e. The direction from the first partial region 10a to the first electrode 51 is along the first direction (Z-axis direction). The direction from the second partial region 10b to the second electrode 52 is along the first direction. The third partial region 10c is between the first partial region 10a and the second partial region 10b in the second direction (X-axis direction). The direction from the third partial region 10c to the third electrode 53 is along the first direction. The fourth partial region 10d is between the first partial region 10a and the third partial region 10c in the second direction. The fifth partial region 10e is located between the third partial region 10c and the second partial region 10b in the second direction.

[0072] The fifth nitride region 15 includes a sixth partial region 15f and a seventh partial region 15g. The direction from the fourth partial region 10d to the sixth partial region 15f is along the first direction (Z-axis direction). The direction from the fifth partial region 10e to the seventh partial region 15g is along the first direction.

[0073] The insulating member 61 is between the nitride member 10M and the third electrode 53. For example, the insulating member 61 includes a first insulating region 61p. The first insulating region 61p is provided between the third partial region 10c and the third electrode 53 in the first direction (the Z-axis direction).

[0074] The semiconductor device 120 may include a nitride semiconductor 111. In the semiconductor device 120, a current flowing between the first electrode 51 and the second electrode 52 can be controlled by the potential of the third electrode 53. The potential of the third electrode 53 is, for example, a potential based on the potential of the first electrode 51. The first electrode 51 functions as, for example, a source electrode. The second electrode 52 functions as, for example, a drain electrode. The third electrode 53 functions as, for example, a gate electrode. In one example, the semiconductor device 120 is a HEMT (High Electron Mobility Transistor). According to the embodiment, a semiconductor device capable of improving characteristics can be provided.

[0075] In the semiconductor device 120, at least a portion of the third electrode 53 is located between the sixth partial region 15f and the seventh partial region 15g in the second direction (for example, the X-axis direction). At least a portion of the third electrode 53 may be located between the fourth partial region 10d and the fifth partial region 10e in the second direction (for example, the X-axis direction). The semiconductor device 120 is, for example, a normally-off type.

[0076] FIG. 6 is a schematic cross-sectional view illustrating the semiconductor device according to the second embodiment. As shown in FIG. 6, the semiconductor device 121 according to the embodiment includes a nitride semiconductor according to the first embodiment (in this example, the nitride semiconductor 110), a first electrode 51, a second electrode 52, a third electrode 53, and an insulating member 61. In the semiconductor device 121, the third electrode 53 does not overlap with the sixth partial region 15f and the seventh partial region 15g in the second direction (for example, the X-axis direction). The third electrode 53 does not overlap with the fourth partial region 10d and the fifth partial region 10e in the second direction (for example, the X-axis direction). The semiconductor device 121 is, for example, a normally-on type.

[0077] (Third Embodiment) The third embodiment relates to a method for manufacturing a nitride semiconductor. The method for manufacturing a nitride semiconductor according to the third embodiment may be applied to a method for manufacturing a wafer or a method for manufacturing a semiconductor device.

[0078] FIG. 7 is a flowchart illustrating a method for manufacturing a nitride semiconductor according to the third embodiment. As shown in FIG. 7, in the method for manufacturing a nitride semiconductor according to the embodiment, a first gas containing carbon is supplied onto a substrate 18s (step S120). After the supply of the first gas, a second gas containing nitrogen is supplied (step S130). On the substrate 18s after the supply of the second gas, Al x1 Ga 1-x1 N (0 < x1 ≦ 1)-containing first nitride region 11 is formed (step S140). After the formation of the first nitride region 11, Al x2 Ga 1-x2 N (0 ≦ x2 < 1, x2 < x1)-containing second nitride region 12 is formed (step S150). By steps S110 and S120, an intermediate region 11M is formed.

[0079] The intermediate region 11M between the substrate 18s and the first nitride region 11 contains nitrogen and carbon. The concentration of carbon in the intermediate region 11M is 1.5 × 10 19 / cm 3 or more and 6 × 10 20 / cm 3 or less. Warpage can be suppressed.

[0080] For example, the first gas is not supplied during at least a portion of the supply of the second gas. For example, the supply of the first gas is stopped, and a second gas containing nitrogen is supplied (step S130). This allows the desired intermediate region 11M to be formed stably. Before the supply of the first gas, the base body 18s may be heat-treated (step S110). This removes unnecessary layers (e.g., a silicon oxide layer) on the surface of the base body 18s. This reduces the oxygen contained in the intermediate region 11M. This allows the desired intermediate region 11M to be formed stably.

[0081] For example, the first gas may include aluminum and carbon. For example, the second gas may include ammonia. For example, the first gas may include carbon and hydrogen. For example, the second gas may include nitrogen.

[0082] In the embodiment, information on the shape of the nitride region is obtained by, for example, electron microscope observation. Information on the composition and element concentration in the nitride region is obtained by, for example, EDX (Energy Dispersive X-ray Spectroscopy) or SIMS (Secondary Ion Mass Spectrometry). Information on the composition in the nitride region may be obtained by, for example, X-ray reciprocal space mapping.

[0083] According to the embodiment, it is possible to provide a nitride semiconductor, a semiconductor device, and a method for manufacturing a nitride semiconductor that are capable of suppressing warpage.

[0084] The above describes the embodiments of the present invention with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configurations of the elements, such as the nitride member, the nitride region, and the substrate, contained in the nitride semiconductor are included in the scope of the present invention as long as a person skilled in the art can implement the present invention in the same manner and obtain the same effects by appropriately selecting them from the known range.

[0085] Furthermore, any combination of two or more elements of each of the specific examples, within the scope of technical feasibility, is also included within the scope of the present invention as long as it includes the gist of the present invention.

[0086] In addition, all nitride semiconductors, semiconductor devices, and methods for manufacturing nitride semiconductors that can be implemented by a person skilled in the art by appropriate design modifications based on the nitride semiconductors, semiconductor devices, and methods for manufacturing nitride semiconductors described above as the embodiments of the present invention also fall within the scope of the present invention, so long as they include the gist of the present invention.

[0087] In addition, within the scope of the concept of the present invention, a person skilled in the art may conceive of various modifications and alterations, and these modifications and alterations are also considered to fall within the scope of the present invention.

[0088] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0089] 10M... nitride member, 10a-10e... first to fifth partial regions, 11-15... first to fifth nitride regions, 11M... intermediate region, 13a, 13b... first and second regions, 14a, 14b... first and second film regions, 15f... sixth partial region, 15g... seventh partial region, 18s... substrate, 51-53... first to third electrodes, 61... insulating member, 61p... first insulating region, 110, 111... nitride semiconductor, 120, 121... semiconductor device, 210, 211... wafer, C(C), C(Si)... concentration, CC1... concentration, Int_Al, Int_N... secondary ion intensity, W1... amount of warpage, pZ... position, t1, t2... first and second region thickness, tm1... intermediate region thickness, tr1 to tr5: thicknesses of the first to fifth nitride regions, tr4a, tr4b: thicknesses of the first and second film regions

Claims

1. A substrate; A nitride member; an intermediate region disposed between the substrate and the nitride member; Equipped with The nitride member is A ｘ１ G １－ｘ１ a first nitride region including N, where 0<x1≦1; A ｘ２ G １－ｘ２ a second nitride region including N (0≦x2<1, x2<x1); Including, the first nitride region is between the intermediate region and the second nitride region; the intermediate region comprises nitrogen and carbon; The carbon concentration in the intermediate region is 1.5×10 １９ / cm ３ Above 6 x 10 ２０ / cm ３ is as follows: At least a portion of the intermediate region comprises silicon.

2. The nitride semiconductor according to claim 1 , wherein the intermediate region is in contact with the substrate.

3. The nitride semiconductor of claim 2 , wherein the intermediate region is in contact with the first nitride region.

4. The nitride semiconductor of claim 3 , wherein the first nitride region is in contact with the second nitride region.

5. The nitride semiconductor according to claim 1, wherein at least a portion of the intermediate region contains aluminum.

6. The nitride semiconductor according to claim 1 , wherein the first nitride region contains AlN.

7. The nitride semiconductor according to claim 1, wherein the substrate contains silicon.

8. The concentration of carbon in the intermediate region is 3×10 １９ / cm ３ Above 4 x 10 ２０ / cm ３ The nitride semiconductor according to any one of claims 1 to 7, wherein:

9. The nitride semiconductor according to any one of claims 1 to 8, wherein the first nitride region does not contain carbon, or a concentration of carbon in the first nitride region is lower than the concentration of carbon in the intermediate region.

10. the second nitride region comprises carbon; The nitride semiconductor of claim 9 , wherein a concentration of carbon in the second nitride region is higher than the concentration of carbon in the first nitride region.

11. A substrate; A nitride member; an intermediate region disposed between the substrate and the nitride member; Equipped with The nitride member is A ｘ１ G １－ｘ１ a first nitride region including N, where 0<x1≦1; A ｘ２ G １－ｘ２ a second nitride region including N (0≦x2<1, x2<x1); Including, the first nitride region is between the intermediate region and the second nitride region; the intermediate region comprises nitrogen and carbon; The carbon concentration in the intermediate region is 1.5×10 １９ / cm ３ Above 6 x 10 ２０ / cm ３ is as follows: the first nitride region is carbon-free or has a lower concentration of carbon than the concentration of carbon in the intermediate region; the second nitride region comprises carbon; A nitride semiconductor, wherein a concentration of carbon in the second nitride region is higher than the concentration of carbon in the first nitride region.

12. The nitride semiconductor according to claim 10 or 11, wherein the concentration of carbon in the second nitride region is lower than the concentration of carbon in the intermediate region.

13. The nitride member is Al ｘ３ G １－ｘ３ N, where 0≦x3≦1; The nitride semiconductor according to any one of claims 1 to 12, wherein the second nitride region is between the first nitride region and the third nitride region.

14. the third nitride region includes a plurality of first regions and a plurality of second regions; in a first direction from the first nitride region to the second nitride region, one of the plurality of first regions is between one of the plurality of second regions and another one of the plurality of second regions, and the one of the plurality of second regions is between the one of the plurality of first regions and another one of the plurality of first regions; The first region is Al ｙ１ G １－ｙ１ N (0<y1≦1), The second region is Al ｙ２ G １－ｙ２ The nitride semiconductor of claim 13 , comprising N (0≦y2<y1).

15. The nitride member is A ｘ４ G １－ｘ４ a fourth nitride region including N (0≦x4<1); and A ｘ５ G １－ｘ５ a fifth nitride region including N (0<x5≦1, x4<x5); Further comprising: the third nitride region is between the first nitride region and the fifth nitride region; the fourth nitride region is between the third nitride region and the fifth nitride region; The nitride semiconductor according to claim 13.

16. The nitride semiconductor according to claim 15 ; A first electrode; A second electrode; A third electrode; An insulating member; Equipped with a direction from the first electrode to the second electrode along a second direction that intersects a direction from the first nitride region to the second nitride region; a position of the third electrode in the second direction is between a position of the first electrode in the second direction and a position of the second electrode in the second direction, the fourth nitride region includes a first sub-region, a second sub-region, a third sub-region, a fourth sub-region, and a fifth sub-region; a direction from the first partial region to the first electrode along a first direction from the first nitride region to the second nitride region; a direction from the second partial region to the second electrode is along the first direction; the third partial region is between the first partial region and the second partial region in the second direction, and a direction from the third partial region to the third electrode is along the first direction; the fourth partial region is between the first partial region and the third partial region in the second direction, the fifth partial region is between the third partial region and the second partial region in the second direction, the fifth nitride region includes a sixth sub-region and a seventh sub-region, a direction from the fourth partial region to the sixth partial region is along the first direction; a direction from the fifth partial region to the seventh partial region is along the first direction; The insulating member is between the nitride member and the third electrode.

17. supplying a first gas containing carbon onto the substrate; Stopping the supply of the first gas; providing a second gas comprising nitrogen to form an intermediate region; On the substrate after the delivery of the second gas, ｘ１ G １－ｘ１ forming a first nitride region including N, where 0<x1≦1; After the formation of the first nitride region, Al ｘ２ G １－ｘ２ A method for manufacturing a nitride semiconductor, comprising forming a second nitride region containing N (0≦x2<1, x2<x1).

18. the intermediate region between the substrate and the first nitride region comprises nitrogen and carbon; The carbon concentration in the intermediate region is 1.5×10 １９ / cm ３ Above 6 x 10 ２０ / cm ３ The method for producing a nitride semiconductor according to claim 17, wherein:

19. The method for producing a nitride semiconductor according to claim 17 or 18, further comprising the step of: heat-treating the base before the supply of the first gas.

20. the first gas contains aluminum and carbon; The method for producing a nitride semiconductor according to any one of claims 17 to 19, wherein the second gas contains ammonia.

21. the first gas comprises a hydrocarbon; The method for producing a nitride semiconductor according to any one of claims 17 to 19, wherein the second gas contains ammonia.

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