Semiconductor substrate, manufacturing method of semiconductor substrate, manufacturing method of semiconductor laser element, and semiconductor laser element

Abstract

This semiconductor substrate includes: a template substrate having a seed portion and an amorphous seed portion; and a GaN-based semiconductor portion located above the template substrate, having a base portion located on the seed portion and a wing portion connected to the base portion; the wing portion having: a first portion located above the amorphous seed portion and containing carbon at a concentration of 10¹⁹ / cm³ or higher; and a second portion located above the amorphous seed portion and having a carbon concentration higher than that of the first portion.

Description

Technical Field

[0001] This invention relates to a semiconductor substrate, etc. Prior Technology

[0002] Patent document 1 discloses a method for laterally growing a GaN-based semiconductor layer on a substrate. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-114263 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] Previous GaN-based semiconductor layers had the problem of large anisotropic strain. [Technical means to solve the problem]

[0006] This semiconductor substrate includes: a template substrate having a seed portion and an amorphous seed portion; and a GaN-based semiconductor portion located above the template substrate, having a base portion located on the seed portion and a wing portion connected to the base portion; the wing portion having: a first portion located above the amorphous seed portion and containing carbon at a concentration of 10 19 / cm 3 or higher; and a second portion located above the amorphous seed portion and having a carbon concentration higher than that of the first portion. [Effects of the Invention]

[0007] In this semiconductor substrate, the anisotropic strain of the GaN-based semiconductor portion can be reduced. Simple Explanation of the Diagram

[0008] Figure 1 is a top view showing the structure of the semiconductor substrate of this embodiment. Figure 2 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 3 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 4 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 5 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 6 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 7 is a cross-sectional view showing the structure of the semiconductor substrate in this embodiment. Figure 8 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 9 is a graph showing the elemental concentration at the base of Figure 8. Figure 10 is a graph showing the elemental concentration of the wing section in Figure 8. Figure 11 is a cross-sectional view showing the structure of this semiconductor substrate. Figure 12 is a cross-sectional view showing the structure of this semiconductor substrate. Figure 13 is a secondary electron image obtained by measuring the cross-section of this semiconductor substrate using SEM. Figure 14 is a CL image obtained from the CL measurement of a cross-section of the semiconductor substrate. Figure 15 is a flowchart illustrating the manufacturing method of the semiconductor substrate according to this embodiment. Figure 16 is a table showing the conditions for the V / III ratio. Figure 17 is a cross-sectional view showing the manufacturing method of the semiconductor substrate according to this embodiment. Figure 18 is a block diagram showing the semiconductor substrate manufacturing apparatus of this embodiment. Figure 19 is a flowchart illustrating the manufacturing method of the semiconductor laser element according to this embodiment. Figure 20 is a cross-sectional view showing the manufacturing method of the semiconductor laser element according to this embodiment. Figure 21 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 22 is a cross-sectional view showing the structure of the semiconductor laser element according to this embodiment. Implementation

[0009] Figure 1 is a top view showing the structure of the semiconductor substrate of this embodiment. Figure 2 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. As shown in Figures 1 and 2, the semiconductor substrate 10 includes: a template substrate TS having a seed portion SA and an amorphous portion (growth suppression portion) DA; and a GaN-based semiconductor portion 8 located above the template substrate TS, having a base portion B located above the seed portion SA and a wing portion W connected to the base portion B.

[0010] The wing W has: a first portion P1, located above the amorphous seed portion DA, containing carbon or germanium (a group of carbon elements) at a concentration of 10¹⁹ / cm³ or higher; and a second portion P2, located above the amorphous seed portion DA, containing the aforementioned group of carbon elements at a higher concentration than that of the first portion P1. The first and second portions P1 and P2 of the wing W may contain carbon (C) at a concentration of 10¹⁹ / cm³ or higher. The carbon concentration of the second portion P2 may be more than 2 times or 4 times that of the carbon concentration of the first portion P1. For example, when the carbon concentration of the first portion P1 is 2.0 × 10¹⁹ to 1.0 × 10²⁰ / cm³, the carbon concentration of the second portion P2 may also be 8.0 × 10¹⁹ to 5.0 × 10²⁰ / cm³.

[0011] By forming the first and second portions P1 and P2 in the wing W, the internal stress (e.g., tensile stress) of the wing W is reduced. As a result, the anisotropic strain of the wing W (e.g., the state of different strain in the first direction X and the second direction Y) is improved, and a high-quality nitride semiconductor layer with less crystal displacement (slip) can be formed above the wing W.

[0012] Seed section SA and amorphous section DA are arranged in the first direction X when viewed from above. First part P1 and second part P2 can be arranged in the first direction X such that first part P1 is located on the base B side relative to second part P2. By applying a gradient to the carbon concentration of the wing W corresponding to the distance from the seed section SA, anisotropic strain can be reduced more effectively. "Viewed from above" refers to a view taken from the normal direction of the template substrate TS, including perspective. "Two components overlapping when viewed from above" can mean "at least a portion of one component overlaps with another component when viewed from the normal direction of the self-substrate 1." When one of the two components is above or below the other, the two components can overlap when viewed from above.

[0013] As shown in Figure 2, the wing W may have a third part P3 located above the first part P1 and having a higher carbon concentration than the first part P1. The carbon concentration of the third part P3 may be more than 2 or 4 times that of the first part P1. For example, when the carbon concentration of the first part P1 is 2.0 × 10¹⁹ to 1.0 × 10²⁰ / cm³, the carbon concentration of the third part P3 may also be 8.0 × 10¹⁹ to 5.0 × 10²⁰ / cm³. The carbon concentrations of the second part P2 and the third part P3 may be of the same level, for example, the difference may be within 2 times (the carbon concentration of the third part P3 is 0.5 to 2 times that of the carbon concentration of the second part P2).

[0014] By configuring the third part P3 on the first part P1, the anisotropic strain of the wing W can be reduced more effectively, and a high-quality nitride semiconductor layer with less m-plane slip (crystallization displacement along the m-plane, which is a cleavage plane) can be formed above the wing W. The third part P3 can be located on the first and second parts P1 and P2.

[0015] The entire wing W may contain carbon (C) with a concentration of 10¹⁹ / cm³ or higher. The entire base B and wing W may also contain carbon (C) with a concentration of 10¹⁹ / cm³ or higher. The second part P2 may also be the entire part of the wing W located in the first direction X of the first part P1. The third part P3 may also be the entire upper part of the wing W containing the first part P1 and the second part P2. The first part P1 may also be the part surrounded (covered) by the second part P2 and the third part P3.

[0016] The length of the second part P2 in the first direction X can also be longer than that of the first part P1. For example, the length of the first part P1 in the first direction X can be 2~20 μm or 5~15 μm. For example, the length of the second part P2 in the first direction X can be 5~100 μm or 10~50 μm. The third part P3 can be thinner than the first part P1.

[0017] The thickness of the first part P1 can be, for example, 1~10 μm, or 2~5 μm. The thickness of the third part P3 can be, for example, 0.5~6 μm, or 1~4 μm. The first part P1 can have tensile strain in the m-axis direction of the GaN semiconductor part 8, and the tensile strain in the m-axis direction of the third part can be smaller than that of the first part P1. The value of the tensile strain can be determined, for example, by stress analysis using Raman spectroscopy or XRD (X-ray diffraction).

[0018] Nitride semiconductors can be represented as AlxGayInzN (0≤x≤1; 0≤y≤1; 0≤z≤1; x+y+z=1). Specific examples include GaN-based semiconductors, AlN (aluminum nitride), InAlN (indium aluminum nitride), and InN (indium nitride). GaN-based semiconductors refer to semiconductors containing both gallium (Ga) and nitrogen (N) atoms. Typical examples include GaN, AlGaN, AlGaInN, and InGaN. The GaN-based semiconductor section 8 includes GaN-based semiconductors as its main component. GaN-based semiconductors can be doped or undoped.

[0019] A semiconductor substrate refers to a substrate containing semiconductors. The main substrate 1 included in the template substrate TS may contain semiconductors (e.g., silicon, silicon carbide) or may not contain semiconductors. A sapphire substrate is an example of a main substrate 1 that does not contain semiconductors. The template substrate TS is sometimes also referred to as a growth substrate. The main substrate 1 can be a self-standing substrate (wafer).

[0020] The a-axis direction of GaN-based semiconductors is, for example, the <11-20> direction, and the m-axis direction is, for example, the <1-100> direction. The thickness direction of the GaN-based semiconductor portion 8 can be the c-axis direction of the GaN-based semiconductor (e.g., <0001> (Direction). In Figure 1, the first direction X can be the a-axis direction (hereinafter, sometimes referred to as the transverse direction), the second direction Y can be the m-axis direction, and the third direction Z can be the c-axis direction (thickness direction).

[0021] The GaN-based semiconductor section 8 can be a GaN-based crystal G1 (e.g., a GaN crystal) that has undergone ELO (epitaxial lateral overgrowth) starting from the seed section SA. In the GaN-based semiconductor section 8, the through-dislocation density of the wing W can be less than 1 / 5, 1 / 10, or 1 / 100 of the through-dislocation density of the base B. The through-dislocation density of the wing W can be less than 5 × 10⁶ / cm².

[0022] Two GaN-based crystals G1 and G2 adjacent in the first direction X, separated by a gap GP, can also be located on the template substrate TS. The GaN-based crystal G1 (GaN-based semiconductor section 8) can include an edge ED located above the amorphous seed section DA. By stopping the growth of the GaN-based crystals G1 and G2 that are reverse-grown in ELO on the amorphous seed section DA before they meet each other (material stop), an island-shaped GaN-based crystal G1 (GaN-based semiconductor section 8) can be formed.

[0023] Figures 3 and 4 are cross-sectional views showing the structure of the semiconductor substrate according to this embodiment. In Figure 2, the wing W includes a third portion P3, but is not limited to this. As shown in Figure 3, the GaN-based semiconductor portion 8 can also be formed by the first and second portions P1 and P2 adjacent in the first direction X. In Figure 2, the first portion P1 is located on the base B side, but is not limited to this. As shown in Figure 4, the second portion P2 (with a higher carbon concentration than the first portion P1) can also be located on the base B side.

[0024] Figure 5 is a cross-sectional view showing the structure of the semiconductor substrate according to this embodiment. As shown in Figure 5, the template substrate TS may include a main substrate 1 mainly composed of non-nitride semiconductors and a base layer 4. The base layer 4 may include a seed crystal portion SA. As the base layer 4, for example, a gallium nitride film (GaN), an aluminum nitride film (AlN), or a mixed crystal film of gallium and aluminum (AlGaN, InGaN, AlInGaN, etc.) can be used. The base layer 4 can be formed by sputtering. Of course, it can also be formed by MOCVD (Metal Organic Chemical Vapor Deposition), MBE (Molecular Beam Epitaxy), etc.

[0025] The template substrate TS has a masking pattern 6, which may include an opening K overlapping with the seed section SA and a masking section 5 that functions as a non-seed section DA. The masking section 5 may include at least one of silicon nitride and silicon oxide.

[0026] In Figure 5, the first portion P1 and the second portion P2 can be arranged in the first direction X with the first portion P1 located on the base B side, and the third portion P3 can be located on the first and second portions P1 and P2. The semiconductor substrate 10 is required to suppress slit-like defects that may occur in the upper functional layer (device layer) due to tensile strain. For example, by containing more than 10 19 / cm 3, compressive strain can be introduced into the GaN-based crystal. As shown in Figure 5, by surrounding (covering) the low-carbon-concentration first portion P1 with the second and third portions P2 and P3 (adjacent portions PS) with high carbon concentration, there are adjacent portions PS (covered portions) with stronger compressive strain closer to the functional layer (device layer), which can effectively suppress slip defects of the functional layer that may occur on the wing W.

[0027] At least a portion of the bottom surface Q1 of the first part P1 is in contact with the amorphous seed part DA, and at least a portion of the bottom surface Q2 of the second part P2 can float from the amorphous seed part DA. This reduces the external force (e.g., tensile force) on the second part P2 from the template substrate TS, and facilitates the cleaving of the wing W. The thickness of the gap JD between the amorphous seed part DA and the second part P2 can be 10 nm or less; the greater the distance from the base B in the first direction X, the greater the thickness of the gap JD between the amorphous seed part DA and the second part P2.

[0028] The higher the carbon content of the GaN-based crystal on the masking portion 5, the easier it is to peel off from the masking portion 5 and the higher the cleavage efficiency. For example, when the wing portion W is used in a laser element, the optical resonant portion (ridge structure) is arranged away from the base portion B in the first direction X when viewed from above, and a resonant end face can be formed by cleavage. Therefore, by bringing the first portion P1 with low carbon concentration close to the base portion B and moving the second portion P2 with high carbon concentration away from the base portion B, it is possible to simultaneously avoid peeling off the GaN-based semiconductor portion 8 and improve the ease of cleavage.

[0029] The base B may include a lower portion BF connected to the first portion P1 and containing a carbon concentration of 10 19 / cm 3 or higher, and an upper portion BT connected to the third portion P3 and containing a carbon concentration higher than that of the lower portion BF. The penetrating dislocation density of the adjacent portions PS (the second and third portions P2 and P3) may be less than 1 / 10 of the penetrating dislocation density of the base B (the upper portion BT). By forming the adjacent portions PS using ELO, the penetrating dislocation density of the adjacent portions PS can be significantly reduced compared to the base B, which is a dislocation successor portion (for example, set to less than 5 × 10 6 / cm 2).

[0030] The first part P1 can have an inverted conical side surface T1, and the second part P2 can have an inverted conical side surface T2 with a larger area than the side surface of the first part P1. This reduces the risk of functional layers on adjacent GaN crystals (GaN-based semiconductor part 8) interconnecting. The transmittance of the third part P3 for light with wavelengths below 500 nm can be lower than that of the first part P1. This suppresses stray light.

[0031] As shown in Figure 5, the first part P1 can also have both an inverted conical side surface T1 and a regular conical side surface TU. In the first part P1, the area of ​​the regular conical side surface TU can be smaller than the area of ​​the inverted conical side surface T1. In the first part P1, the area of ​​the regular conical side surface TU can also be larger than the area of ​​the inverted conical side surface T1. The side surface T2 of the second part P2 can also include a plurality of sides with different tilt angles relative to the template substrate TS. Furthermore, the term "inverted conical" refers to a shape where the distance from the base B increases with distance from the template substrate TS. Side surfaces T1 and T2 can also have different tilt angles relative to the surface of the template substrate TS. The tilt angle of side surface T1 relative to the surface of the template substrate TS can also be larger than that of side surface T2. The tilt angle of side surface T1 relative to the surface of the template substrate TS can also be smaller than that of side surface T2.

[0032] The template substrate TS may include a main substrate 1 (silicon wafer, silicon carbide wafer, sapphire wafer, etc.) with a lattice constant different from that of the GaN-based semiconductor section 8 (e.g., GaN layer). The coefficient of thermal expansion of the main substrate 1 may be smaller than that of the GaN-based semiconductor section 8. The first portion P1 and the second portion P2 may be layers containing GaN. The first portion P1, the second portion P2, and the third portion P3 may be single-crystal layers of GaN.

[0033] Figures 6 and 7 are cross-sectional views showing the structure of the semiconductor substrate according to this embodiment. As shown in Figure 6, the semiconductor substrate 10 may have a nitride semiconductor layer LA containing Al above the third portion P3. The nitride semiconductor layer LA may be an aluminum gallium nitride layer (AlGaN layer).

[0034] As shown in Figure 7, above the third region P3, a nitride semiconductor layer LS with a larger lattice constant and coefficient of thermal expansion than the GaN-based semiconductor region 8 may also be included. The nitride semiconductor layer LS may be an indium gallium nitride layer (InGaN layer). This InGaN layer may have a composition (atomic ratio relative to Ga) of 3% to 20% and a thickness of 10 nm to 300 nm. Alternatively, a GaN layer LG (e.g., a silicon-doped n-GaN layer) may be disposed on the nitride semiconductor layer LS.

[0035] Figure 8 is a cross-sectional view showing the structure of the semiconductor substrate according to this embodiment. As shown in Figure 8, a functional layer 9 (e.g., a stacked body of nitride semiconductors) may also be provided on the GaN-based semiconductor portion 8. The functional layer 9 may include an n-type semiconductor layer, an active layer, and a p-type semiconductor layer.

[0036] Figure 9 is a graph showing the elemental concentration of the portion including the base of Figure 8. Figure 10 is a graph showing the elemental concentration of the portion including the wing of Figure 8. As shown in Figure 9, the carbon concentration of the lower part BF is 10¹⁹ / cm³ or higher, and the carbon concentration of the upper part BT is higher than that of the lower part BF (more than 3 times that of the lower part BF). As shown in Figure 10, the carbon concentration of the first part P1 is 10¹⁹ / cm³ or higher, and the carbon concentration of the second and third parts P2 and P3 (adjacent parts PS) is higher than that of the first part P1 (more than 3 times that of the first part P1).

[0037] In the semiconductor substrate 10, the first region P1 contains silicon (Si), and the carbon concentration in the first region P1 may be higher than the silicon concentration. The first region P1 also contains oxygen (O), and the silicon concentration in the first region P1 may also be higher than the oxygen concentration. As shown in Figures 9 and 10, the second and third regions P2 and P3 (adjacent regions PS) contain silicon, and the carbon concentration in the second and third regions P2 and P3 (adjacent regions PS) may be higher than the silicon concentration. The second region P2 contains oxygen, and the silicon concentration in the second region P2 may be higher than the oxygen concentration.

[0038] Figures 9 and 10 show the results of SIMS analysis. The measuring apparatus used was an IMS-7f manufactured by CAMECA. The measurement conditions were as follows: Cs+ was used as the primary ion species, the primary accelerating voltage was set to 15 kV, and the detection area was set to Φ8 μm. The concentrations of each component in the first region P1, the second region P2, and the third region P3 can be the average concentrations of the corresponding regions in the SIMS analysis, or the average concentrations within any depth range (e.g., 0.5 μm to 1.0 μm) of the corresponding regions. As a specific method for each region in the semiconductor substrate 10, it can be visually confirmed based on SEM or TEM images, or it can be confirmed by overlaying SEM or TEM images with the SIMS analysis results.

[0039] Figure 11 is a cross-sectional view showing the structure of the semiconductor substrate. As shown in Figure 11, the base layer 4 of the template substrate TS may have a modified portion 4D that functions as an amorphous seed portion DA and an unmodified portion 4S that functions as a seed portion SA.

[0040] Figure 12 is a cross-sectional view showing the structure of this semiconductor substrate. As shown in Figure 12, the GaN-based semiconductor section 8 has a raised section R that is connected to the seed section SA (4S) of the substrate layer 4, and the growth inhibition film 7 is located on the side of the raised section R. The void JD can be located between the amorphous seed section DA (4D) and the first and second portions P1 and P2 of the wing section W (the wing section W is entirely floating from the template substrate TS). The growth inhibition film 7 can be a silicon compound film such as a silicon nitride film, and the growth inhibition film 7 can also be located on the amorphous seed section DA (4D).

[0041] Figure 13 shows a cross-sectional SEM secondary electron image of the GaN-based semiconductor part 8. Here, a difference in carrier density is observed in the secondary electron image. It is believed that because the second part P2 contains more carbon as impurities than the first part P1, the carrier density is lower, and this difference is confirmed in the detected secondary electron image. As an electron microscope, SCM (Scanning Capacitance Microscopy) or SNDM (Scanning Nonlinear Dielectric Microscopy) can also be used.

[0042] Regarding the GaN-based semiconductor part 8, the part directly above the seed part SA (for example, the part corresponding to the lower part BF) has a carbon concentration of 10 19 / cm3 or higher and the carbon concentration can also be higher than that of the first part P1. This type of configuration is also included in the present invention.

[0043] Figure 14 is a CL (cathode luminescence) image obtained from a cross-section of the semiconductor substrate. The GaN semiconductor portion 8 has a first crystal portion 11 including a first portion P1, and a second crystal portion 12 including a second portion P2 and a third portion P3. In the CL measurement method, the brightness of the first crystal portion 11 may be higher than that of the second crystal portion 12. The first crystal portion 11 may include a lower portion BF, and the second crystal portion 12 may also include an upper portion BT.

[0044] In the CL measurement, the basic luminescence intensity of the first crystallization part 11 relative to the basic luminescence intensity of the second crystallization part 12 can be between 2 and 1000. Here, as the conditions for CL measurement, a scanning electron microscope (SEM) manufactured by JEOL JSM-7000F and a detector manufactured by HORIBA MP-32S can be used, and the accelerating voltage is set to 3 kV for measurement.

[0045] In Figure 14, the white portion of the GaN semiconductor section 8 is the first crystal section 11, and the black portion of the GaN semiconductor section 8 is the second crystal section 12. As shown in Figure 14, the central portion of the GaN semiconductor section 8 can also be the second crystal section 12.

[0046] The GaN-based semiconductor portion 8 may also include a portion containing the first portion P1 that is relatively lightly illuminated (high-tone display) when the secondary electron image is confirmed using a scanning electron microscope such as SEM, and a portion containing the second portion P2 and the third portion P3 that is relatively heavily illuminated (low-tone display) when the secondary electron image is confirmed using SEM. In this case, the lightly illuminated portion may be the first crystal portion 11, and the heavily illuminated portion may be the second crystal portion 12.

[0047] Figure 15 is a flowchart illustrating the manufacturing method of the semiconductor substrate according to this embodiment. Figure 16 is a table showing the conditions for the V / III ratio. Figure 17 is a cross-sectional view illustrating the manufacturing method of the semiconductor substrate according to this embodiment. In Figures 15 to 17, the following steps are performed to manufacture the semiconductor substrate 10. The semiconductor substrate 10 includes a template substrate TS having a seed portion SA and an amorphous portion DA, and a GaN-based semiconductor portion 8 located above the template substrate TS and having a base portion B located above the seed portion SA and a wing portion W connected to the base portion B. That is, the following steps are performed: step (S30), which prepares a template substrate TS; step (S40), which, during the first period, alternately executes (e.g., repeats) a first film-forming condition and a second film-forming condition in which the V / III ratio is greater than the first film-forming condition, and forms the lower part BF of the base B and the first part P1 of the wing W by ELO; and step (S45), which, during the second period, alternately executes (e.g., repeats) a third film-forming condition in which the V / III ratio is less than the first film-forming condition and a fourth film-forming condition in which the V / III ratio is greater than the first film-forming condition and the V / III ratio is less than the second film-forming condition, and forms the upper part BT of the base B and the adjacent part PS of the wing W that is connected to the first part P1 (the second and third parts P2, P3) by ELO.

[0048] The feedstock supplied during Period 1 (ELO period for BF and P1) and Period 2 (ELO period for BT and PS) contains Group III elements, Group V elements, and carbon (C). The V / III ratio refers to the molar ratio of Group V elements (e.g., nitrogen) to Group III elements (e.g., Ga, Al, In) in the supplied feedstock. Carbon may be included in the Group III element source or in the Group V element source. A separate carbon source may also be supplied.

[0049] The adjacent portion PS may cover the first portion P1, and may include a second portion P2 that is adjacent to the first portion P1 in the a-axis direction (first direction X) of the GaN semiconductor portion, and a third portion P3 located above the first portion P1. The third portion P3 may be located on the first and second portions P1 and P2.

[0050] The V / III ratio of the second film-forming condition is more than 5 times that of the first film-forming condition; the V / III ratio of the third film-forming condition is less than half that of the first film-forming condition; and the V / III ratio of the fourth film-forming condition can be more than 6 times that of the third film-forming condition. The V-III ratio of the first film-forming condition can be 50-90, the V-III ratio of the second film-forming condition can be 450-650, the V-III ratio of the third film-forming condition can be 15-30, and the V-III ratio of the fourth film-forming condition can be 100-300. As shown in the specific example in Figure 16, the V / III ratio of the first film-forming condition can be 68, the V / III ratio of the second film-forming condition can be 546, the V / III ratio of the third film-forming condition can be 21, and the V / III ratio of the fourth film-forming condition can be 215.

[0051] Under the first to fourth film-forming conditions, the V / III ratio can be controlled by substantially fixing the supply amount of a Group III element source (e.g., gallium source) and changing the supply amount of a Group V element source (e.g., nitrogen source). Trimethylgallium or triethylgallium can be used as the gallium source (Group III element source), and ammonia can also be used as the nitrogen source (Group V element source).

[0052] Figure 18 is a block diagram showing the semiconductor substrate manufacturing apparatus of this embodiment. The semiconductor substrate manufacturing apparatus 60 includes a device M30 for performing step S30 of Figure 15, a device M50 (MOCDV device) for performing steps S40 and S45 of Figure 15, and a control device MC for controlling the devices M30 and M50.

[0053] Figure 19 is a flowchart illustrating the manufacturing method of the semiconductor laser element according to this embodiment. Figure 20 is a cross-sectional view illustrating the manufacturing method of the semiconductor laser element according to this embodiment. Figures 19 and 20 include the following steps: Step S70, a semiconductor substrate 10 is prepared, the semiconductor substrate 10 having a seed portion SA and an amorphous portion DA, and a GaN-based semiconductor portion 8 located above the template substrate TS and having a base portion B located above the seed portion SA and a wing portion W connected to the base portion B. The wing portion W has a first portion P1 located above the amorphous portion DA and containing a carbon concentration of 10¹⁹ / cm³ or higher, and a second portion P2 located above the amorphous portion DA and containing a carbon concentration higher than that of the first portion P1; Step S80, a functional layer 9 including a photoresonance portion LR is formed above the wing portion W; and Step S90, cleaving (e.g., m-plane) is performed on the wing portion W and the photoresonance portion LR. The cleavage surface CF generated by the cleavage in step S90 is the resonant end face of the optical resonant part LR. The cleavage surface CF can be along the m-plane (the plane perpendicular to the m-axis) of the GaN semiconductor part 8.

[0054] The first part P1 and the second part P2 are adjacent in the a-axis direction of the GaN semiconductor part 8. At least a portion of the bottom surface Q1 of the first part P1 is in contact with the amorphous seed part DA, and at least a portion of the bottom surface Q2 of the second part P2 can float from the amorphous seed part DA. In this case, cleavage becomes easier.

[0055] Figure 21 is a cross-sectional view showing the structure of the semiconductor substrate of this embodiment. Figure 22 is a cross-sectional view showing the structure of the semiconductor laser element of this embodiment. Before or after step S90 in Figure 19, the semiconductor substrate 10 (laser element array substrate) shown in Figure 21 can be obtained by forming a plurality of electrodes (anode EA, cathode EC) and insulating film located on the functional layer 9. If the template substrate TS is peeled off from the semiconductor substrate 10 in Figure 21, the semiconductor laser element 20 in Figure 22 can be obtained.

[0056] The semiconductor laser element 20 includes: a substrate (GaN-based semiconductor portion) 8, which contains a GaN-based semiconductor and has a first portion P1 and a second portion P2 arranged in a first direction X; and an optical resonant portion LR, which is located above the substrate 8 and contains a nitride semiconductor; the first portion P1 contains carbon with a concentration of 10 19 / cm3 or higher, and the second portion P2 may have a higher carbon concentration than the first portion P1. The optical resonant portion LR may be located above the first portion P1, and the optical resonant portion LR may also be located above the second portion P2.

[0057] By positioning the optical resonant portion LR above the second portion P2, it is less susceptible to the effects of defects (dislocation inheritance) from the seed portion SA, thereby improving the quality of the semiconductor laser element 20. When viewed from above, the optical resonant portion LR can overlap with at least one of the second portion P2 and the third portion P3.

[0058] The optical resonant portion LR can be located above the boundary between portion 1 P1 and portion 2 P2 (the optical resonant portion LR and the boundary can also overlap when viewed from above). The optical resonant portion LR can be contained in the functional layer 9 located on the substrate 8. The through-dislocation density of portion 2 P2 can be less than 1 / 10 of the through-dislocation density of the base B (upper portion BT).

[0059] The substrate 8 may have a third portion P3 located above the first portion P1 and having a higher carbon concentration than the first portion P1. The carbon concentration of the third portion P3 may be more than twice that of the first portion P1. The third portion P3 may be located above the first and second portions P1 and P2. The through dislocation density of the third portion P3 may be less than 1 / 10 of the through dislocation density of the base B (the upper portion BT).

[0060] The first direction is the a-axis direction of the X-based GaN semiconductor. The optical resonant section LR includes at least one of AlGaN and InGaN. The carbon concentration of the second section P2 can be more than three times that of the carbon concentration of the first section P1. The resonant end face RF of the optical resonant section LR can be a cleavage plane along the m-plane of the GaN semiconductor. The optical resonant section LR can include an n-type semiconductor layer 9N and a p-type semiconductor layer 9P, and an active layer 9A located between the n-type semiconductor layer 9N and the p-type semiconductor layer 9P.

[0061] The active layer 9A can be a quantum well-structured light-emitting layer, for example, it can also emit light with a peak wavelength of less than 500 nm. At least one of the n-type semiconductor layer 9N and the p-type semiconductor layer 9P can include a cladding layer for encapsulating light. At least one of the n-type semiconductor layer 9N and the p-type semiconductor layer 9P can include an AlGaN layer. The second and third portions P2 and P3 can be colored portions. The carbon concentration of the p-type semiconductor layer 9P can be less than 1 / 10 of the carbon concentration of the first portion P1 of the substrate 8. The semiconductor laser element 20 can be rod-shaped. On the back side of the semiconductor laser element 20 (the surface below the base B), there can be peel marks (e.g., areas where the surface roughness is locally more than twice) VA. (Additional Notes)

[0062] The above disclosure is for illustrative and explanatory purposes only and is not intended to limit. It should be noted that many variations will be obvious to practitioners based on these illustrations and explanations, and therefore such variations are also included in the implementation.

[0063] 1: Main base board 4: Basal layer 4D: Quality Modification Department 4S: Non-modification department 5: Masking section 6: Masking Pattern 8: GaN-based semiconductors (substrate) 9: Functional Layer 9A: Active layer 9N: n-type semiconductor layer 9P: p-type semiconductor layer 10: Semiconductor substrate 11: First crystallization section 12: Second crystallization section 20: Semiconductor laser elements (semiconductor devices) 60: Manufacturing equipment B: Base BF: Lower part BT: Upper part CF: Cleavage surface DA: Amorphous seed region (growth inhibition region) EA: Anode EC: Cathode ED: Edge G1: GaN-based crystals G2: GaN-based crystalline solid GP: gap JD: Gap K: Opening LA: Nitride semiconductor layer LG:GaN layer LR: Optical Resonance Section LS: Nitride semiconductor layer M30: Device M50: Device MC: Control device P1: Part 1 P2: Part 2 P3: Part 3 PS: Adjacent parts Q1: Bottom surface Q2: Bottom surface S30: Steps S40: Steps S45: Steps S70: Steps S80: Steps S90: Steps SA: Seed section (seed region) T1: Side view T2: Side view TS: Template substrate TU: Side view VA: Peeling marks W: Wing

Claims

1. A semiconductor substrate comprising: a template substrate having a seed portion and an amorphous seed portion; and a GaN-based semiconductor portion located above the template substrate and having a base portion located above the seed portion and a wing portion connected to the base portion; the wing portion having: a first portion located above the amorphous seed portion and containing carbon at a concentration of 10 19 / cm 3 or higher; and a second portion located above the amorphous seed portion and having carbon at a higher concentration than the first portion.

2. The semiconductor substrate of claim 1, wherein the carbon concentration of the second part is more than twice that of the carbon concentration of the first part.

3. The semiconductor substrate of claim 1, wherein the seed portion and the amorphous portion are arranged in a first direction when viewed from above, and the first portion and the second portion are arranged in the first direction such that the first portion is located on the base side.

4. The semiconductor substrate of claim 1, wherein the wing has a third portion, the third portion being located above the first portion and having a higher concentration of carbon than the first portion.

5. The semiconductor substrate of claim 4, wherein the carbon concentration of the third portion is more than twice the carbon concentration of the first portion.

6. The semiconductor substrate of claim 4, wherein the third portion is thinner than the first portion.

7. A semiconductor substrate as claimed in any one of claims 1 to 6, wherein the first portion has tensile strain in the m-axis direction of the GaN-based semiconductor portion.

8. The semiconductor substrate of claim 4, wherein the tensile strain in the m-axis direction of the GaN-based semiconductor portion is smaller in the third portion compared to the first portion.

9. A semiconductor substrate according to any one of claims 1 to 6, wherein at least a portion of the bottom surface of the first portion is in contact with the amorphous seed portion, and at least a portion of the bottom surface of the second portion is raised from the amorphous seed portion.

10. The semiconductor substrate of claim 9, wherein the thickness of the gap between the amorphous seed portion and the second portion is 10 nm or less.

11. In the semiconductor substrate of claim 9, the greater the distance from the base in the first direction, the greater the thickness of the gap between the amorphous seed portion and the second portion.

12. The semiconductor substrate of claim 4, wherein the base comprises: a lower portion connected to the first portion and containing carbon at a concentration of 10 19 / cm3 or higher; and an upper portion connected to the third portion and containing carbon at a higher concentration than the lower portion.

13. The semiconductor substrate of any one of claims 1 to 6, wherein the first portion described above has an inverted conical side surface.

14. The semiconductor substrate of claim 13, wherein the second portion has an inverted conical side surface with an area larger than that of the side surface of the first portion.

15. The semiconductor substrate of any one of claims 1 to 6, wherein the template substrate comprises a main substrate having a lattice constant different from that of the GaN-based semiconductor portion.

16. The semiconductor substrate of claim 15, wherein the coefficient of thermal expansion of the main substrate is smaller than that of the GaN-based semiconductor.

17. The semiconductor substrate of any one of claims 1 to 6, wherein the first portion and the second portion are GaN layers.

18. The semiconductor substrate of claim 4, wherein the transmittance of the third portion to light with a wavelength of less than 500 nm is smaller than that of the first portion.

19. A semiconductor substrate according to any one of claims 1 to 6, wherein the template substrate has a masking pattern, the masking pattern including an opening overlapping the seed portion and a masking portion that functions as the non-seed portion.

20. A semiconductor substrate as claimed in any one of claims 1 to 6, wherein the template substrate has a base layer, the base layer having a modified portion that functions as the amorphous seed portion and a non-modified portion that functions as the seed portion.

21. The semiconductor substrate of claim 3, wherein a plurality of GaN-based crystals comprising the GaN-based semiconductor portion are arranged in the first direction with gaps between them.

22. A method for manufacturing a semiconductor substrate, the semiconductor substrate comprising: a template substrate having a seed portion and an amorphous portion; and a GaN-based semiconductor portion located above the template substrate and having a base portion located on the seed portion and a wing portion connected to the base portion; and the method for manufacturing the semiconductor substrate comprising the steps of: alternately performing a first film deposition condition and a second film deposition condition having a V / III ratio greater than the first film deposition condition to form a first portion of the wing portion; and alternately performing a third film deposition condition having a V / III ratio less than the first film deposition condition and a fourth film deposition condition having a V / III ratio greater than the first film deposition condition and a V / III ratio less than the second film deposition condition to form an adjacent portion of the wing portion connected to the first portion.

23. The method for manufacturing a semiconductor substrate as claimed in claim 22, wherein the adjacent portion covers the first portion.

24. The method for manufacturing a semiconductor substrate as claimed in claim 22 or 23, wherein the V / III ratio of the second film-forming condition is more than 5 times the V / III ratio of the first film-forming condition.

25. A method for manufacturing a semiconductor substrate as claimed in claim 22 or 23, wherein the V / III ratio of the third film-forming condition is less than 1 / 2 of the V / III ratio of the first film-forming condition.

26. The method for manufacturing a semiconductor substrate as claimed in claim 22 or 23, wherein the V / III ratio of the fourth film-forming condition is more than 6 times the V / III ratio of the third film-forming condition.

27. The method for manufacturing a semiconductor substrate as claimed in claim 22 or 23, wherein, under the first to fourth film-forming conditions described above, the V / III ratio is controlled by substantially fixing the supply amount of the gallium source and changing the supply amount of the nitrogen source.

28. A method for manufacturing a semiconductor substrate as claimed in claim 22 or 23, wherein trimethylgallium or triethylgallium is used as a gallium source and ammonia is used as a nitrogen source.

29. A method for manufacturing a semiconductor laser element, comprising the following steps: preparing a semiconductor substrate, the semiconductor substrate comprising: a template substrate having a seed portion and an amorphous seed portion; and a GaN-based semiconductor portion located above the template substrate, having a base portion located above the seed portion and a wing portion connected to the base portion; and the wing portion having: a first portion located above the amorphous seed portion and containing carbon at a concentration of 10 19 / cm 3 or higher; and a second portion located above the amorphous seed portion and having a carbon concentration higher than that of the first portion; forming an optical resonant portion above the wing portion; and performing cleaving of the wing portion and the optical resonant portion.

30. The method for manufacturing a semiconductor laser element as claimed in claim 29, wherein the cleavage surface generated by the above-mentioned cleavage is along the m-plane of the GaN-based semiconductor portion.

31. A method for manufacturing a semiconductor laser element as claimed in claim 29 or 30, wherein the first portion and the second portion are adjacent in the a-axis direction of the GaN-based semiconductor portion, at least a portion of the bottom surface of the first portion is in contact with the amorphous seed portion, and at least a portion of the bottom surface of the second portion is raised from the amorphous seed portion.

32. A semiconductor laser element comprising: a substrate comprising a GaN-based semiconductor and having a first portion and a second portion arranged in a first direction; and an optical resonant portion located above the substrate and comprising a nitride semiconductor; wherein the first portion comprises carbon with a concentration of 10 19 / cm 3 or higher, and the second portion has a higher concentration of carbon than the first portion.

33. The semiconductor laser element of claim 32, wherein the first direction is the a-axis direction of the GaN-based semiconductor, the optical resonant portion comprises at least one of AlGaN and InGaN, and the carbon concentration of the second portion is more than three times that of the carbon concentration of the first portion.

34. The semiconductor laser element of claim 32 or 33, wherein the optical resonant portion includes a resonant end face, the resonant end face being along the cleavage plane of the m-plane of the GaN-based semiconductor.

35. The semiconductor laser element of claim 32 or 33, wherein the optical resonant portion includes a p-type semiconductor layer, and the carbon concentration of the p-type semiconductor layer is less than 1 / 10 of the carbon concentration of the first portion.

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