Nitride semiconductors and semiconductor devices

Abstract

To provide a nitride semiconductor and a semiconductor device, capable of improving characteristics.SOLUTION: According to one embodiment, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region, a second nitride region, and an intermediate region. The first nitride region includes Alx1Ga1-x1N (0≤x1<1) including a first element including at least one selected from the group consisting of Fe and Mn. The second nitride region includes Alx2Ga1-x2N (0≤x2<1). A direction from the first nitride region to the second nitride region is along a first direction. The intermediate region is provided between the first nitride region and the second nitride region. The intermediate region includes Alz1Ga1-z1N (0<z1≤1, x1<z1, x2<z1) including oxygen. A concentration of oxygen in the nitride member becomes maximum in the intermediate region.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to nitride semiconductors and semiconductor devices.

Background Art

[0002] For example, in a semiconductor device based on a nitride semiconductor, improvement in characteristics 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 and a semiconductor device capable of improving characteristics.

Means for Solving the Problems

[0005] According to an embodiment of the present invention, a nitride semiconductor includes a nitride member. The nitride member includes a first nitride region, a second nitride region, and an intermediate region. The first nitride region includes Al containing a first element selected from the group consisting of at least one of Fe and Mn, x1 Ga 1-x1 N (0 ≦ x1 <1). The second nitride region includes Al x2 Ga 1-x2 N (0 ≦ x2 <1). The direction from the first nitride region to the second nitride region is along a first direction. The intermediate region is provided between the first nitride region and the second nitride region. The intermediate region includes Al containing oxygen z1 Ga 1-z1 N (0 <z1 ≦ 1, x1 <z1, x2 <z1). The oxygen concentration in the nitride member is maximized in the intermediate region.

Brief Description of the Drawings

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating a nitride semiconductor according to the first embodiment. [Figure 2] Figures 2(a) and 2(b) are graphs illustrating a nitride semiconductor according to the first embodiment. [Figure 3] Figures 3(a) and 3(b) are graphs illustrating nitride semiconductors according to the first embodiment. [Figure 4] Figures 4(a) and 4(b) are graphs illustrating a nitride semiconductor according to the first embodiment. [Figure 5] Figure 5 is a graph illustrating a nitride semiconductor according to the first embodiment. [Figure 6] Figures 6(a) and 6(b) are graphs illustrating nitride semiconductors. [Figure 7] Figure 7 is an electron microscope image illustrating a nitride semiconductor according to the first embodiment. [Figure 8] Figure 8 is a schematic cross-sectional view illustrating a semiconductor device according to the second embodiment. [Modes for carrying out the invention]

[0007] The embodiments of the present invention will be described below with reference to the drawings. Drawings are schematic or conceptual, and the relationships between the thickness and width of each part, as well as the ratios of the sizes of different parts, are not necessarily identical to those of reality. Even when representing the same part, the dimensions and ratios may be depicted differently in different drawings. In this specification and in each figure, elements similar to those described above are denoted by the same reference numerals with respect to previously shown figures, and detailed explanations are omitted as appropriate.

[0008] (First Embodiment) Figure 1 is a schematic cross-sectional view illustrating a nitride semiconductor according to the first embodiment. As shown in Figure 1, the nitride semiconductor 110 according to this embodiment includes a nitride member 10M.

[0009] The nitride member 10M includes a first nitride region 11, a second nitride region 12, and an intermediate region 12M. The nitride member 10M is, for example, a crystal. The first nitride region 11, the second nitride region 12, and the intermediate region 12M are, for example, crystals.

[0010] The first nitride region 11 contains Al x1 Ga 1-x1 N (0 ≦ x1 < 1). Al x1 Ga 1-x1 N (0 ≦ x1 < 1) contains a first element selected from the group consisting of Fe and Mn. Al x1 Ga 1-x1 In N, the composition ratio x1 is, for example, 0 or more and 0.1 or less. Al x1 Ga 1-x1 N may be, for example, GaN. The first nitride region 11 may be, for example, GaN containing the first element. The first nitride region 11 is, for example, Fe-doped GaN or Mn-doped GaN.

[0011] The second nitride region 12 contains Al x2 Ga 1-x2 N (0 ≦ x2 < 1). Al x2 Ga 1-x2 In N, the composition ratio x2 is, for example, 0 or more and 0.1 or less. Al x2 Ga 1-x2 N may be, for example, GaN. The first concentration of the first element in the first nitride region 11 is higher than the second concentration of the first element in the second nitride region 12. Or, the second nitride region 12 does not contain the first element. The second nitride region 12 is, for example, non-doped GaN.

[0012] The direction from the first nitride region 11 to the second nitride region 12 follows the first direction D1. The first direction D1 is the Z-axis direction. One direction perpendicular to the Z-axis direction is the X-axis direction. The direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction. The first nitride region 11 and the second nitride region 12 extend substantially parallel to the X-Y plane.

[0013] The intermediate region 12M is provided between the first nitride region 11 and the second nitride region 12. The intermediate region 12M contains Al z1 Ga 1-z1 N (0 < z1 ≦ 1, x1 < z1, x2 < z1). In Al z1 Ga 1-z1 N, the composition ratio z1 is 0.8 or more and 1 or less. The intermediate region 12M contains, for example, AlGaN or AlN. The concentration of oxygen in the nitride member 10M becomes maximum in the intermediate region 12M. The intermediate region 12M may be in contact with the second nitride region 12.

[0014] In an embodiment, since the first nitride region 11 contains the first element, a high electrical resistance is obtained in the first nitride region 11. The first nitride region 11 is, for example, an insulating or semi-insulating substrate. By using such a first nitride region 11, stable operation can be obtained in a semiconductor device using the nitride semiconductor 110. The intermediate region 12M may be in contact with the first nitride region 11.

[0015] When the first nitride region 11 contains the first element, the first element may move (for example, diffuse) to the second nitride region 1 or the nitride region thereon. When the first element moves, it may be difficult to obtain the desired characteristics in a semiconductor device using the nitride semiconductor to. When the first element moves, for example, the carrier mobility decreases. When the first element moves, for example, the current collapse becomes large and it becomes difficult to obtain stable operation. When the first element moves, for example, the reliability decreases.

[0016] In an embodiment, as described above, the concentration of oxygen in the nitride member 10M becomes maximum in the intermediate region 12M. Such an intermediate region 12M can obtain a low concentration of the first element in the second nitride region 12 or the nitride region thereon even when the first nitride region 11 contains the first element. According to the embodiment, a nitride semiconductor capable of improving characteristics can be provided. According to the embodiment, for example, a nitride semiconductor capable of realizing high carrier mobility can be provided.

[0017] It is considered that the movement of the first element from the first nitride region 11 to the second nitride region 12 is suppressed by the intermediate region 12M containing oxygen. For example, oxygen (or a structure based on oxygen) is considered to function as a trap that captures the first element.

[0018] In an embodiment, for example, the concentration of oxygen in the intermediate region 12M is higher than the concentration of oxygen in the first nitride region 11 and higher than the concentration of oxygen in the second nitride region 12. Or, the first nitride region 11 and the second nitride region 12 do not contain oxygen.

[0019] For example, if the first nitride region 11 contains oxygen at a high concentration, it is difficult to obtain high crystallinity in the first nitride region 11. For example, if the second nitride region 12 contains oxygen at a high concentration, it is difficult to obtain high crystallinity in the second nitride region 12. For example, in a semiconductor device using the nitride semiconductor 110, it is difficult to obtain the desired characteristics. For example, current leakage is likely to increase.

[0020] As shown in FIG. 1, in this example, the nitride member 10M further includes a third nitride region 13. The third nitride region 13 contains Al x3 Ga 1-x3 N (0 < x3 ≤ 1, x2 < x3). In Al x3 Ga 1-x3 N, for example, the composition ratio x3 is 0.05 or more and 1 or less. The composition ratio x3 may be 0.15 or more and 0.3 or less. The third nitride region 13 is, for example, AlGaN.

[0021] There is a second nitride region 12 between the first nitride region 11 and the third nitride region 13. The second nitride region 12 may be in contact with the third nitride region 13. As shown in FIG. 1, the second nitride region 12 includes a region facing the third nitride region 13. A carrier region 12Q may be formed in this region. The carrier region 12Q is, for example, a two-dimensional electron gas. In the operation of a semiconductor device using the nitride semiconductor 110, the carrier region 12Q is used.

[0022] Figures 2(a) and 2(b) are graphs illustrating a nitride semiconductor according to the first embodiment. These figures show examples of SIMS (Secondary Ion Mass Spectrometry) analysis results for the first sample SP1. The first sample SP1 is obtained by forming an intermediate region 12M on top of a first nitride region 11, a second nitride region 12 on top of the intermediate region 12M, and a third nitride region 13 on top of the second nitride region 12. These regions are formed by epitaxial growth. When forming the intermediate region 12M, an oxygen-containing source gas is used to form an oxygen-containing intermediate region 12M. In this example, a source gas containing oxygen and hydrocarbons is used.

[0023] Figures 2(a) and 2(b) show the elemental profiles in the nitride member 10M along the Z-axis. In this example, the first element is Fe. The horizontal axis in these figures represents the position pZ along the Z-axis. The left vertical axis in Figure 2(a) represents the concentration of Fe (C(Fe)). The right vertical axis in Figure 2(a) represents the detection intensity of Al (Int(Al)). The vertical axis in Figure 2(b) represents the concentration of oxygen (C(O)). These figures show the first nitride region 11, the intermediate region 12M, the second nitride region 12, and the third nitride region 13, respectively.

[0024] As shown in Figure 2(a), the concentration of Al is high in the intermediate region 12M and the third nitride region 13. Fe is present at a high concentration in the first nitride region 11. The concentration of Fe decreases sharply in the intermediate region 12M. In the intermediate region 12M, the movement (e.g., diffusion) of Fe from the first nitride region 11 to the second nitride region 12 is suppressed. The high concentration of Fe detected in the third nitride region 13 is thought to be due to surface adsorbents in the nitride member 10M.

[0025] As shown in Figure 2(b), the oxygen concentration reaches a maximum in the intermediate region 12M. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration in the first nitride region 11. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration in the second nitride region 12. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration at the intermediate position 12p in the first direction D1 of the second nitride region 12 (see Figures 2(b) and 1). The high oxygen concentration in the region of the second nitride region 12 that is close to the third nitride region 13 is thought to be due to surface adsorbents in the nitride member 10M.

[0026] As shown in Figure 2(b), the oxygen concentration in the intermediate region 12M is, for example, 5 × 10⁻⁶ 16 cm -3 That concludes the explanation. The oxygen concentration in the first nitride region 11 is, for example, 5 × 10⁻⁶ 16 cm -3 It is less than . The oxygen concentration at the intermediate position 12p of the second nitride region 12 is, for example, 5 × 10 16 cm -3 It is less than.

[0027] The oxygen concentration in the intermediate region of 12M is, for example, 5 × 10⁻⁶. 18 cm -3 The following is true: The oxygen concentration in the intermediate region of 12M is 5 × 10⁻⁶. 17 cm -3 The following is also acceptable. For example, if the intermediate region 12M contains an excessively high concentration of oxygen, it becomes difficult to obtain high crystallinity in the second nitride region 12. For example, in semiconductor devices using nitride semiconductors 110, current leakage tends to increase.

[0028] As shown in Figure 2(a), the concentration of the first element (Fe) in the first nitride region 11 (first concentration) is higher than the concentration of the first element in the second nitride region 12 (second concentration). Alternatively, the second nitride region 12 does not contain the first element.

[0029] The first concentration is, for example, 1 × 10⁻⁶ 17 cm -3This completes the process. As a result, sufficient insulating properties can be obtained in the first nitride region 11. The second concentration is, for example, 1 × 10 17 cm -3 It is less than. The second concentration is, for example, 5 × 10 15 cm -3 The following are also acceptable: The second concentration is, for example, 1 / 10 or less of the first concentration. The concentration of the first element (e.g., Fe) at intermediate position 12p is 1 / 10 or less of the first concentration. The second concentration may also be, for example, 1 / 100 or less of the first concentration. The concentration of the first element (e.g., Fe) at intermediate position 12p may also be 1 / 100 or less of the first concentration.

[0030] Figures 3(a) and 3(b) are graphs illustrating nitride semiconductors according to the first embodiment. These figures show examples of SIMS analysis results for the first sample, SP1. The horizontal axis in these figures represents the position pZ in the Z-axis direction. The vertical axis in Figure 3(a) represents the silicon concentration (C(Si)). The vertical axis in Figure 3(b) represents the carbon concentration (C(C)).

[0031] As shown in Figure 3(a), the silicon concentration in the intermediate region 12M may be higher than the silicon concentration in the first nitride region 11. The silicon concentration in the intermediate region 12M may be higher than the silicon concentration in the second nitride region 12. For example, the silicon concentration in the intermediate region 12M may be higher than the silicon concentration at the intermediate position 12p. Alternatively, the first nitride region 11 and the second nitride region 12 may not contain silicon.

[0032] For example, the intermediate region 12M locally contains silicon. In the intermediate region 12M, the movement (e.g., diffusion) of the first element is suppressed. For example, the silicon-containing structure functions as a trap.

[0033] For example, the silicon concentration in the intermediate region of 12M is 1 × 10⁻⁶ 17 cm -3 The above 5 x 10 18 cm -3 The following applies: For example, if the silicon concentration is 1 × 10⁻⁶ 17 cm-3 If the silicon concentration is lower than 5 × 10, the crystallinity of the second nitride region 12 tends to decrease. For example, if the silicon concentration is 5 × 10 18 cm -3 If the value is higher than this, current leakage is more likely to occur in the intermediate region of 12M.

[0034] As shown in Figure 3(b), the carbon concentration in the intermediate region 12M may be higher than the carbon concentration in the first nitride region 11. The carbon concentration in the intermediate region 12M may be higher than the carbon concentration in the second nitride region 12. The carbon concentration in the intermediate region 12M may be higher than the carbon concentration at the intermediate position 12p. Alternatively, the first nitride region 11 and the second nitride region 12 may not contain carbon.

[0035] For example, the intermediate region 12M locally contains carbon. In the intermediate region 12M, the movement (e.g., diffusion) of the first element is suppressed. For example, the carbon acts as a trap.

[0036] The carbon concentration in the intermediate region of 12M is, for example, 1 × 10⁻⁶. 17 cm -3 The above 5 x 10 18 cm -3 The following applies: For example, if the carbon concentration is 1 × 10 17 cm -3 If the value is lower than this, current leakage is likely to occur in the intermediate region of 12M. For example, if the carbon concentration is 5 × 10 18 cm -3 If the value is higher than this, the crystallinity of the second nitride region 12 tends to decrease.

[0037] As shown in Figures 1 and 2(a), the second nitride region 12 includes a region 12r that is in contact with the third nitride region 13. The thickness of this contacting region 12r in the first direction D1 is 1 / 10 of the thickness of the second nitride region 12 in the first direction D1. The concentration of the first element (e.g., Fe) in this contacting region 12r is 1 / 20 or less of the concentration of the first element in the first nitride region 11.

[0038] Figures 4(a) and 4(b) are graphs illustrating a nitride semiconductor according to the first embodiment. These figures show an example of the SIMS analysis results for sample 2, SP2. In sample 2, the first element is Mn. Aside from this, the composition of sample 2, SP2, is the same as that of sample 1, SP1.

[0039] The horizontal axis in Figures 4(a) and 4(b) represents the position pZ in the Z-axis direction. The left vertical axis in Figure 4(a) represents the concentration of Mn (C(Mn)). The right vertical axis in Figure 4(a) represents the detection intensity of Al (Int(Al)). The vertical axis in Figure 4(b) represents the concentration of oxygen (C(O)).

[0040] As shown in Figure 4(a), the concentration of Al is high in the intermediate region 12M and the third nitride region 13. Mn is present at a high concentration in the first nitride region 11. The concentration of Mn decreases sharply in the intermediate region 12M. In the intermediate region 12M, the movement (e.g., diffusion) of Mn from the first nitride region 11 to the second nitride region 12 is suppressed.

[0041] As shown in Figure 4(a), the concentration of Mn (first element) in the first nitride region 11 (first concentration) is higher than the concentration of Mn (first element) in the second nitride region 12 (second concentration). The second nitride region 12 does not need to contain the first element.

[0042] As shown in Figure 4(b), the oxygen concentration reaches a maximum in the intermediate region 12M. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration in the first nitride region 11. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration in the second nitride region 12. For example, the oxygen concentration in the intermediate region 12M is higher than the oxygen concentration at the intermediate position 12p (see Figure 4(b)) in the first direction D1 of the second nitride region 12.

[0043] As shown in Figure 4(b), the oxygen concentration in the intermediate region 12M is, for example, 5 × 10⁻¹⁰ 16 cm -3That concludes the explanation. The oxygen concentration in the first nitride region 11 is, for example, 5 × 10⁻⁶ 16 cm -3 It is less than . The oxygen concentration at the intermediate position 12p of the second nitride region 12 is, for example, 5 × 10 16 cm -3 It is less than.

[0044] The oxygen concentration in the intermediate region of 12M is, for example, 5 × 10⁻⁶. 18 cm -3 The following is true: The oxygen concentration in the intermediate region of 12M is 5 × 10⁻⁶. 17 cm -3 The following is also acceptable. For example, if the intermediate region 12M contains an excessively high concentration of oxygen, it becomes difficult to obtain high crystallinity in the second nitride region 12. For example, in semiconductor devices using nitride semiconductors 110, current leakage tends to increase.

[0045] In the second sample SP2, the first concentration is, for example, 1 × 10 17 cm -3 That's all. The second concentration is, for example, 1 × 10⁻⁶. 17 cm -3 It is less than. The second concentration is, for example, 5 × 10 15 cm -3 The following is also acceptable.

[0046] Even when the first element is Mn, the provision of an intermediate region 12M containing oxygen locally can suppress the movement (e.g., diffusion) of the first element into the second nitride region 12.

[0047] For silicon and carbon, it is acceptable for the second sample SP2 to have the same profile as the first sample SP1.

[0048] Figure 5 is a graph illustrating a nitride semiconductor according to the first embodiment. In Figure 5, the horizontal axis represents the position pZ in the Z-axis direction. The vertical axis represents the logarithm of the concentration of the first element (C(E1)).

[0049] As shown in Figure 5, the intermediate concentration C12M of the first element in the intermediate region 12M decreases along the first direction from the first nitride region 11 to the second nitride region 12. The second concentration C12 of the first element in the second nitride region 12 decreases along the first direction from the first nitride region 11 to the second nitride region 12. The first concentration C11 of the first element in the first nitride region 11 may also decrease along the first direction from the first nitride region 11 to the second nitride region 12.

[0050] The rate of change of the intermediate concentration C12M with respect to the change in position pZ along the first direction is higher than the rate of change of the first concentration C11 with respect to the change in position pZ. For example, the logarithmic rate of change of the intermediate concentration C12M with respect to the change in position pZ along the first direction is higher than the logarithmic rate of change of the first concentration C11 with respect to the change in position pZ. As already explained, the first concentration C11 is the concentration of the first element in the first nitride region 11.

[0051] The rate of change of the intermediate concentration C12M with respect to the change in position pZ along the first direction is higher than the rate of change of the second concentration C12 with respect to the change in position pZ. For example, the logarithmic rate of change of the intermediate concentration C12M with respect to the change in position pZ along the first direction is higher than the logarithmic rate of change of the second concentration C12 with respect to the change in position pZ. As already explained, the second concentration C12 is the concentration of the first element in the second nitride region 12.

[0052] The rate of change of the second concentration C12 with respect to the change in position pZ along the first direction is higher than the rate of change of the first concentration C11 with respect to the change in position pZ. For example, the logarithmic rate of change of the second concentration C12 with respect to the change in position pZ along the first direction is higher than the logarithmic rate of change of the first concentration C11 with respect to the change in position pZ.

[0053] In the intermediate region 12M, the concentration of the first element decreases sharply. In the second nitride region 12, a low concentration of the first element is obtained.

[0054] As shown in Figure 1, the intermediate region thickness t12M of the intermediate region 12M along the first direction D1 is, for example, between 0.5 nm and 4 nm. If the intermediate region thickness t12M is thinner than 0.5 nm, for example, current leakage is likely to occur in the intermediate region 12M. If the intermediate region thickness t12M is thicker than 4 nm, the crystal quality of the second nitride region 12 is likely to deteriorate.

[0055] The thickness t12 of the second nitride region 12 along the first direction D1 is, for example, between 10 nm and 1000 nm. If the thickness t12 of the second nitride region is less than 10 nm, the crystal quality tends to deteriorate in the second nitride region 12 or the nitride region above it. If the thickness t12 of the second nitride region is thicker than 1000 nm, the electrical resistance in the second nitride region 12 becomes low, and current leakage is more likely to occur.

[0056] The thickness t11 of the first nitride region 11 along the first direction D1 is, for example, 10 μm or more and 1000 μm or less. For example, the first nitride region 11 is Al x1 Ga 1-x1 The substrate contains N(0≦x1<1). For example, Al x1 Ga 1-x1 N includes at least one selected from the group consisting of Fe and Mn. Current leakage is easily suppressed when the thickness t11 of the first nitride region is 10 μm or more. Stable operation can be obtained in a semiconductor device using the nitride semiconductor 110. When the thickness t11 of the first nitride region is thicker than 1000 μm, malfunctions due to defects and the like are likely to occur.

[0057] The thickness t13 of the third nitride region 13 along the first direction D1 is, for example, 10 nm or more and 50 nm or less. If the thickness t13 of the third nitride region is less than 10 nm, the carrier region 12Q is difficult to form. Mobility tends to decrease. If the thickness t13 of the third nitride region is thicker than 50 nm, the third nitride region Area 1 In step 3, defects tend to increase. Mobility tends to decrease.

[0058] Figures 6(a) and 6(b) are graphs illustrating nitride semiconductors. These figures are examples of the SIMS analysis results of the third sample SP3. In the third sample SP3, the intermediate region 12M is not provided. The first element is Fe. The composition of the third sample SP3 except for this is the same as the composition of the first sample SP1. The third sample SP3 corresponds to the reference example.

[0059] As shown in FIG. 6(a), in the third sample SP3, the concentration of Fe in the second nitride region 12 is higher than the concentration of Fe in the second nitride region 12 in the first sample SP1. The concentration of Fe in the second nitride region 12 is 1×10 17 cm -3 or more. It is difficult to obtain the desired characteristics in the semiconductor device based on the third sample SP3.

[0060] As shown in FIG. 6(b), in the third sample SP3, the oxygen concentration is less than 5×10 16 cm -3 . In the third sample SP3, the oxygen concentration does not peak in the nitride member 10M. The oxygen concentration in the first nitride region 11 is, for example, less than 5×10 16 cm -3 . The oxygen concentration at the intermediate position 12p in the second nitride region 12 is, for example, less than 5×10 16 cm -3 .

[0061] In the first sample SP1, the second sample SP2, and the third sample SP3, the characteristics of the carrier mobility are different. In the first sample SP1, the second sample SP2, and the third sample SP3, the carrier mobility is evaluated by Hall effect measurement. In the first sample SP1, a high carrier mobility of 1850 cm 2 / Vs is obtained. In the second sample SP2, a high carrier mobility of 1830 cm 2 / Vs is obtained. In the third sample SP3, the carrier mobility is as low as 1600 cm 2 / Vs. Thus, in the second nitride region 12, a high carrier mobility is obtained due to the low concentration of the first element.

[0062] Figure 7 is an electron microscope image illustrating a nitride semiconductor according to the first embodiment. Figure 7 shows a TEM (Transmission Electron Microscopy) image of the first sample SP1 described above. As shown in Figure 7, the crystal lattice of the intermediate region 12M (intermediate crystal lattice) is continuous with the crystal lattice of the first nitride region 11 (first crystal lattice). The crystal lattice of the second nitride region 12 (second crystal lattice) is continuous with the intermediate crystal lattice. Good crystal quality is obtained. For example, in the direction perpendicular to the Z-axis direction (e.g., the X-axis direction), the lattice length of the first nitride region 11 is substantially the same as the lattice length of the intermediate region 12M. The first nitride region 11 and the intermediate region 12M are lattice-matched. For example, in the direction perpendicular to the Z-axis direction (e.g., the X-axis direction), the lattice length of the second nitride region 12 is substantially the same as the lattice length of the intermediate region 12M. The second nitride region 12 and the intermediate region 12M are lattice-matched.

[0063] In this embodiment, forming the intermediate region 12M at a high temperature (e.g., 1100°C or higher) makes it easier for the crystal lattice of the intermediate region 12M (intermediate crystal lattice) to become continuous with the crystal lattice of the first nitride region 11 (first crystal lattice). The crystal lattice of the second nitride region 12 (second crystal lattice) also becomes continuous with the intermediate crystal lattice. Good crystal quality can be obtained. In forming the intermediate region 12M, a raw material gas containing oxygen may be used. For example, by using an acetylene gas containing oxygen, the oxygen contained in the raw material gas is easily incorporated into the intermediate region 12M.

[0064] (Second Embodiment) The second embodiment relates to a semiconductor device. Figure 8 is a schematic cross-sectional view illustrating a semiconductor device according to the second embodiment. As shown in Figure 8, the semiconductor device 120 according to the embodiment includes a nitride semiconductor 110 according to the first embodiment, a first electrode 51, a second electrode 52, and a third electrode 53.

[0065] The direction from the first electrode 51 to the second electrode 52 follows the second direction D2. The second direction D2 intersects the first direction D1.

[0066] The position of the third electrode 53 in the second direction D2 is between the position of the first electrode 51 in the second direction D2 and the position of the second electrode 52 in the second direction D2. The second nitride region 12 includes a first subregion 12a, a second subregion 12b, and a third subregion 12c. The direction from the first subregion 12a to the first electrode 51 is along the first direction D1. The direction from the second subregion 12b to the second electrode 52 is along the first direction D1. The third subregion 12c is located between the first subregion 12a and the second subregion 12b in the second direction D2. The direction from the third subregion 12c to the third electrode 53 is along the first direction D1.

[0067] The first electrode 51 is electrically connected to a portion of the third nitride region 13. The second electrode 52 is electrically connected to another portion of the third nitride region 13. The first electrode 51, the second electrode 52, and the third electrode 53 may extend, for example, along a third direction D3. The third direction D3 intersects a plane containing the first direction D1 and the second direction D2. The third direction D3 is, for example, the Y-axis direction.

[0068] In the semiconductor device 120, the 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 referenced to the potential of the first electrode 51. The first electrode 51 functions, for example, as a source electrode. The second electrode 52 functions, for example, as a drain electrode. The third electrode 53 functions, for example, as a gate electrode. The semiconductor device 120 is, for example, a HEMT (High Electron Mobility Transistor). The semiconductor device 120 is, for example, a high-frequency transistor.

[0069] As shown in Figure 8, a first insulating member 41 may be provided. The third nitride region 13 is provided between the second nitride region 12 and the first insulating member 41.

[0070] In this example, the third electrode 53 is in contact with the third nitride region 13. High-speed switching characteristics are obtained. A first insulating member 41 may be provided between the third electrode 53 and the third nitride region 13.

[0071] According to the embodiment, a low concentration of the first element can be obtained in the second nitride region 12. For example, high carrier mobility can be obtained. According to the embodiment, defects can be suppressed. For example, defects caused by the first element can be suppressed. For example, pits can be suppressed. As a result, for example, current leakage can be suppressed. According to the embodiment, a semiconductor device capable of improved characteristics can be provided.

[0072] The semiconductor device 120 can, for example, achieve high carrier mobility. For example, it can suppress current collapse. High reliability can be achieved.

[0073] In the embodiment, information regarding the shape of the nitride region can be obtained, for example, by electron microscopy observation. Information regarding the composition and elemental concentration in the nitride region can be obtained, for example, by EDX (Energy Dispersive X-ray Spectroscopy) or SIMS. Information regarding the composition in the nitride region may also be obtained, for example, by X-ray reciprocal lattice space mapping or photoluminescence.

[0074] The embodiment may include the following configuration (e.g., proposed technical details). (Composition 1) A first nitride region, wherein the first nitride region contains Al, which includes at least one element selected from the group consisting of Fe and Mn. x1 Ga 1-x1 The first nitride region includes N(0≦x1<1), A second nitride region, wherein the second nitride region is Al x2 Ga 1-x2 The region N(0≦x2<1) is included, and the direction from the first nitride region to the second nitride region is along the first direction, and the second nitride region is along the first direction. An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region contains Al z1 Ga 1-z1 N (0 < z1 ≦ 1, x1 < z1, x2 < z1), the intermediate region, and including a nitride member containing a nitride semiconductor in which the concentration of oxygen in the nitride member is maximized in the intermediate region.

[0075] (Configuration 2) The concentration of oxygen in the intermediate region is higher than the concentration of oxygen in the first nitride region, or the first nitride region does not contain oxygen, The concentration of oxygen in the intermediate region is higher than the concentration of oxygen at an intermediate position in the first direction of the second nitride region, the nitride semiconductor according to Configuration 1.

[0076] (Configuration 3) The concentration of oxygen in the intermediate region is 5 × 10 16 cm -3 or more, The concentration of oxygen in the first nitride region is 5 × 10 16 cm -3 less than, The concentration of oxygen at the intermediate position is 5 × 10 16 cm -3 less than, the nitride semiconductor according to Configuration 2.

[0077] (Configuration 4) The first concentration of the first element in the first nitride region is higher than the second concentration of the first element in the second nitride region, or the second nitride region does not contain the first element, the nitride semiconductor according to any one of Configurations 1 to 3.

[0078] (Configuration 5) The first concentration is 1 × 10 17 cm -3 or more, the nitride semiconductor according to Configuration 4.

[0079] (Configuration 6) The intermediate concentration of the first element in the intermediate region decreases along the first direction from the first nitride region to the second nitride region. The nitride semiconductor according to configuration 4 or 5, wherein the rate of change of the intermediate concentration with respect to a change in position along the first orientation is higher than the rate of change of the second concentration with respect to the change in position.

[0080] (Composition 7) The nitride semiconductor according to configuration 6, wherein the rate of change of the intermediate concentration is higher than the rate of change of the first concentration with respect to the change of the position.

[0081] (Composition 8) The nitride semiconductor according to any one of configurations 1 to 7, wherein the intermediate region thickness of the intermediate region along the first direction is 0.5 nm or more and 4 nm or less.

[0082] (Composition 9) The nitride semiconductor according to configuration 8, wherein the thickness of the second nitride region along the first direction is 10 nm or more and 1000 nm or less.

[0083] (Composition 10) The nitride semiconductor according to configuration 9, wherein the thickness of the first nitride region along the first direction is 10 μm or more and 1000 μm or less.

[0084] (Composition 11) The nitride semiconductor according to any one of configurations 1 to 10, wherein the carbon concentration in the intermediate region is higher than the carbon concentration in the first nitride region and higher than the carbon concentration in the second nitride region, or the first nitride region and the second nitride region do not contain carbon.

[0085] (Composition 12) The carbon concentration in the aforementioned intermediate region is 1 × 10 17 cm -3 The above 5 x 10 18 cm -3 The nitride semiconductor described in configuration 11 is as follows.

[0086] (Structure 13) The concentration of silicon in the intermediate region is higher than the concentration of silicon in the first nitride region and higher than the concentration of silicon in the second nitride region, or the first nitride region and the second nitride region do not contain silicon, and the nitride semiconductor according to any one of Structures 1 to 12.

[0087] (Structure 14) The concentration of silicon in the intermediate region is 1×10 17 cm -3 or more and 5×10 18 cm -3 or less, and the nitride semiconductor according to Structure 13.

[0088] (Structure 15) The nitride member further includes a third nitride region containing Al x3 GaN(0 < x3 ≤ 1, x2 < x3), There is the second nitride region between the first nitride region and the third nitride region, and the nitride semiconductor according to any one of Structures 1 to 14.

[0089] (Structure 16) The second nitride region includes a region in contact with the third nitride region, The thickness of the contact region in the first direction is 1 / 10 of the thickness of the second nitride region in the first direction, The concentration of the first element in the contact region is 1 / 20 or less of the concentration of the first element in the first nitride region, and the nitride semiconductor according to Structure 15.

[0090] (Structure 17) A first nitride region, the first nitride region includes a first element containing at least one selected from the group consisting of Fe and Mn, and Al x1 Ga 1-x1 N(0 ≤ x1 < 1), and the first nitride region, A second nitride region, the second nitride region includes Alx2Ga1-x2N (0 ≦ x2 < 1), the direction from the first nitride region to the second nitride region is along a first direction, the second nitride region, and An intermediate region provided between the first nitride region and the second nitride region, the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≦ 1, x1 < z1, x2 < z1), the intermediate region, and A nitride member including The first concentration of the first element in the first nitride region is higher than the second concentration of the first element in the second nitride region, The intermediate concentration of the first element in the intermediate region decreases along a first direction from the first nitride region to the second nitride region, The rate of change of the intermediate concentration with respect to the change in position along the first direction is higher than the rate of change of the first concentration with respect to the change in the position and higher than the rate of change of the second concentration with respect to the change in the position, a nitride semiconductor.

[0091] (Configuration 18) The nitride semiconductor according to Configuration 17, wherein the second concentration decreases along the first direction.

[0092] (Configuration 19) The nitride semiconductor according to Configuration 15 or 16, and A first electrode, A second electrode, A third electrode, Comprising, The direction from the first electrode to the second electrode is along a second direction intersecting the first direction, The position of the third electrode in the second direction is between the position of the first electrode in the second direction and the position of the second electrode in the second direction, The second nitride region includes a first partial region, a second partial region, and a third partial region, The direction from the first partial region to the first electrode is along the first direction, The direction from the second subregion to the second electrode is along the first direction, The third subregion lies between the first subregion and the second subregion in the second direction, and the direction from the third subregion to the third electrode is along the first direction. The first electrode is electrically connected to a portion of the third nitride region, A semiconductor device wherein the second electrode is electrically connected to another part of the third nitride region.

[0093] (Composition 20) The semiconductor device according to configuration 19, wherein the third electrode is in contact with the third nitride region.

[0094] (Composition 21) The aforementioned x1 is between 0 and 0.1, The aforementioned x2 is between 0 and 0.1, The nitride semiconductor according to any one of configurations 1 to 18, wherein z1 is between 0.8 and 1.

[0095] (Composition 22) The aforementioned x1 is between 0 and 0.1, The aforementioned x2 is between 0 and 0.1, The aforementioned x3 is between 0.15 and 0.3, The nitride semiconductor according to configuration 15 or 16, wherein z1 is 0.8 or more and 1 or less.

[0096] According to the embodiment, nitride semiconductors and semiconductor devices with improved properties can be provided.

[0097] In this specification, "electrically connected state" includes a state in which multiple conductors are physically in contact and an electric current flows between them. "Electrically connected state" also includes a state in which another conductor is inserted between multiple conductors and an electric current flows between them.

[0098] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configuration of each element, such as the nitride region and substrate, included in the nitride semiconductor is included within the scope of the present invention as long as the present invention can be implemented in the same manner and similar effects can be obtained by appropriately selecting from the range known to those skilled in the art.

[0099] Furthermore, combinations of two or more elements from any of the specific examples, to the extent technically feasible, are also included within the scope of the present invention, insofar as they encompass the gist of the invention.

[0100] Furthermore, all nitride semiconductors and semiconductor devices that can be implemented by those skilled in the art by appropriately modifying the design based on the nitride semiconductors and semiconductor devices described above as embodiments of the present invention also fall within the scope of the present invention, insofar as they encompass the gist of the present invention.

[0101] Furthermore, within the scope of the concept of the present invention, a person skilled in the art could conceive of various modifications and alterations, and these modifications and alterations are also understood to fall within the scope of the present invention.

[0102] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0103] 10M: Nitride material, 11~13: 1st to 3rd nitride regions, 12M: Intermediate region, 12Q: Carrier region, 12a~12c: 1st to 3rd partial regions, 12p: Intermediate position, 12r: Region, 41: 1st insulating material, 51~53: 1st to 3rd electrodes, 110: Nitride semiconductor, 120: Semiconductor device, C11: 1st concentration, C12: 2nd concentration, C12M: Intermediate concentration, D1~D3: 1st to 3rd directions, SP1~SP3: 1st to 3rd samples, t11: Thickness of the 1st nitride region, t12: Thickness of the 2nd nitride region, t12M: Thickness of the intermediate region, t13: Thickness of the 3rd nitride region,

Claims

1. A first nitride region, wherein the first nitride region contains Al, which includes at least one element selected from the group consisting of Fe and Mn. ｘ１ Ga １－ｘ１ The first nitride region includes N (0 ≤ x1 < 1), A second nitride region, wherein the second nitride region is Al ｘ２ Ga １－ｘ２ Including N (0 ≤ x² < 1), the direction from the first nitride region to the second nitride region is along the first direction, and the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region contains oxygen-containing Al ｚ１ Ga １－ｚ１ The intermediate region includes N (0 < z1 ≤ 1, x1 < z1, x2 < z1), Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. The oxygen concentration in the intermediate region is higher than the oxygen concentration in the first nitride region, or the first nitride region does not contain oxygen. The oxygen concentration in the intermediate region is higher than the oxygen concentration at the intermediate position in the first direction of the second nitride region. The oxygen concentration in the aforementioned intermediate region is 5 × 10¹⁶ cm⁻³ or higher. The oxygen concentration in the first nitride region is less than 5 × 10¹⁶ cm⁻³. A nitride semiconductor in which the oxygen concentration at the intermediate position is less than 5 × 10¹⁶ cm⁻³.

2. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. The first concentration of the first element in the first nitride region is higher than the second concentration of the first element in the second nitride region, or the second nitride region does not contain the first element. The first concentration is 1 × 10 １７ cm －３ That concludes the explanation of nitride semiconductors.

3. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. The first concentration of the first element in the first nitride region is higher than the second concentration of the first element in the second nitride region, or the second nitride region does not contain the first element. The intermediate concentration of the first element in the intermediate region decreases along the first direction from the first nitride region to the second nitride region. A nitride semiconductor in which the rate of change of the intermediate concentration with respect to a change in position along the first direction is higher than the rate of change of the second concentration with respect to the change in position.

4. The nitride semiconductor according to claim 3, wherein the rate of change of the intermediate concentration is higher than the rate of change of the first concentration with respect to the change of the position.

5. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. A nitride semiconductor in which the intermediate region thickness along the first direction is 0.5 nm or more and 4 nm or less.

6. The nitride semiconductor according to claim 5, wherein the thickness of the second nitride region along the first direction is 10 nm or more and 1000 nm or less.

7. The nitride semiconductor according to claim 6, wherein the thickness of the first nitride region along the first direction is 10 μm or more and 1000 μm or less.

8. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. A nitride semiconductor in which the carbon concentration in the intermediate region is higher than the carbon concentration in the first nitride region and higher than the carbon concentration in the second nitride region, or in which the first nitride region and the second nitride region do not contain carbon.

9. The concentration of carbon in the intermediate region is 1×10 １７ cm －３ or more and 5×10 １８ cm －３ or less. The nitride semiconductor according to claim 8.

10. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. A nitride semiconductor in which the silicon concentration in the intermediate region is higher than the silicon concentration in the first nitride region and higher than the silicon concentration in the second nitride region, or in which the first nitride region and the second nitride region do not contain silicon.

11. The concentration of silicon in the intermediate region is 1 × 10 １７ cm －３ The above 5 x 10 １８ cm －３ The nitride semiconductor according to claim 10, which is as follows:

12. The nitride member is Al ｘ３ Ga １－ｘ３ Further including a third nitride region containing N (0 < x3 ≤ 1, x2 < x3), The nitride semiconductor according to claim 1, wherein the second nitride region is located between the first nitride region and the third nitride region.

13. A first nitride region comprising Al x1 Ga 1-x1 N (0 ≤ x1 < 1) which includes a first element comprising at least one selected from the group consisting of Fe and Mn, A second nitride region, wherein the second nitride region includes Al x2 Ga 1-x2 N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region includes Al z1 Ga 1-z1 N (0 < z1 ≤ 1, x1 < z1, x2 < z1) containing oxygen, Includes a nitride component containing, The oxygen concentration in the nitride member reaches a maximum in the intermediate region. The nitride member further includes a third nitride region containing Al x3 Ga 1-x3 N (0 < x3 ≤ 1, x2 < x3), The second nitride region is located between the first nitride region and the third nitride region. The second nitride region includes a region in contact with the third nitride region. The thickness of the contacting region in the first direction is 1 / 10 of the thickness of the second nitride region in the first direction. A nitride semiconductor in which the concentration of the first element in the contact region is 1 / 20 or less of the concentration of the first element in the first nitride region.

14. A first nitride region, wherein the first nitride region contains Al, which includes at least one element selected from the group consisting of Fe and Mn. ｘ１ Ga １－ｘ１ The first nitride region includes N (0 ≤ x1 < 1), A second nitride region, wherein the second nitride region includes Alx2Ga1-x2N (0 ≤ x2 < 1), and the direction from the first nitride region to the second nitride region is along the first direction, An intermediate region provided between the first nitride region and the second nitride region, wherein the intermediate region is Al ｚ１ Ga １－ｚ１ The intermediate region includes N (0 < z1 ≤ 1, x1 < z1, x2 < z1), Includes a nitride component containing, The first concentration of the first element in the first nitride region is higher than the second concentration of the first element in the second nitride region. The intermediate concentration of the first element in the intermediate region decreases along the first direction from the first nitride region to the second nitride region. A nitride semiconductor in which the rate of change of the intermediate concentration with respect to a change in position along the first orientation is higher than the rate of change of the first concentration with respect to the change in position, and is higher than the rate of change of the second concentration with respect to the change in position.

15. The nitride semiconductor according to claim 14, wherein the second concentration decreases along the first direction.

16. The nitride semiconductor according to claim 12, First electrode and, The second electrode and The third electrode and Equipped with, The direction from the first electrode to the second electrode is along the second direction which intersects the first direction. The position of the third electrode in the second direction is between the position of the first electrode in the second direction and the position of the second electrode in the second direction. The second nitride region includes a first subregion, a second subregion, and a third subregion. The direction from the first subregion to the first electrode is along the first direction, The direction from the second subregion to the second electrode is along the first direction, The third subregion is located between the first subregion and the second subregion in the second direction, and the direction from the third subregion to the third electrode is along the first direction. The first electrode is electrically connected to a portion of the third nitride region, A semiconductor device wherein the second electrode is electrically connected to another part of the third nitride region.

17. The semiconductor device according to claim 16, wherein the third electrode is in contact with the third nitride region.

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