Method of growing group iii-nitride semiconductor layer

Abstract

The present disclosure relates to a method of growing group III-nitride semiconductor layers, comprising the steps of: preparing a substrate; forming, on the substrate, one from among a GaN buffer layer and a sputtered AlN buffer layer, the GaN buffer layer being grown using MOCVD at a growth temperature of 1000 °C to 1200 °C, a growth pressure of 100 mbar or higher (>100 mbar), and in an atmosphere of H2 and N2; and forming, on the buffer layer, an N-polar group III-nitride semiconductor layer, wherein N-polar GaN is grown using MOCVD at a temperature of 1100 °C to 1200 °C, a growth pressure of 200 mbar or higher, and in an atmosphere of H2 and N2.

Description

Method for growing a group 3 nitride semiconductor layer

[0001] The present disclosure relates to a method of growing III-nitride semiconductor layers in general, and in particular to a method of growing a III-nitride semiconductor layer that can be used in diodes such as LEDs and laser diodes, transistors such as power devices, etc. Here, the III-nitride semiconductor is composed of a compound of Al(a)Ga(b)In(1-ab)N (0≤a≤1, 0≤b≤1, 0≤a+b≤1).

[0002] This section provides background information related to the present disclosure, which is not necessarily prior art.

[0003] FIG. 1 is a diagram illustrating an example of a method for growing a group 3 nitride semiconductor layer as disclosed in U.S. Patent Publication No. 5,290,393, wherein, using an MOCVD method, a group 3 nitride semiconductor layer (30; e.g., Ga) is formed on a substrate (10; e.g., a sapphire substrate). x Al x-1 A technique for growing a high-quality group 3 nitride semiconductor layer (30) is presented by introducing a buffer layer (20) grown at a low temperature (400~800℃) when growing the N layer. The group 3 nitride semiconductor layer (30) grown in this way has Ga-polar polarity.

[0004] Meanwhile, U.S. Patent Publication No. 8,455,885 and the paper (Review of polarity determination and control of GaN (MRS Internet Journal of Nitride Semiconductor Research, Received Friday, November 21, 2003; accepted Monday, February 9, 2004)) present a method for growing N-polar group III nitride semiconductor layers. When used as light-emitting devices such as LEDs and laser diodes, the N-polar group III nitride semiconductor layer offers: ① reduction of the piezoelectric field (in Ga-polar GaN structures, a strong internal electric field is generated within the quantum well, which causes spatial separation of electrons and holes, lowering the recombination probability and degrading luminous efficiency. In N-polar GaN structures, an internal electric field is formed in the opposite direction to that of Ga-polar GaN; this reduces the spatial separation of electrons and holes, enables efficient recombination, and improves luminous efficiency), and ② quality improvement (during the growth process of N-polar GaN, the surface is relatively flat and possesses high crystal quality It often has, which lowers defect density and reduces non-radiative recombination, thereby improving LED luminous efficiency. Particularly in N-polar GaN, dislocation density can be lowered, allowing optical losses to be minimized.), ③ Optimization of quantum well efficiency (In the case of N-polar GaN, hole injection efficiency within quantum wells is improved compared to Ga-polar. This alleviates the problem of holes not being properly injected into MQWs due to their lower mobility compared to electrons, thereby further enhancing luminous efficiency.), ④ Suppression of non-radiative recombination pathways (Provides high electron density at the GaN / AlGaN interface.(Applied when growing SLs)), ⑤ It is known that when growing InGaN, In is easily incorporated (in the case of N-polar, the activation energy is higher compared to Ga-polar), etc. In addition, when used as a transistor such as a power device, N-polar group 3 nitride semiconductor layers are known to enable: ① excellent high-speed electron transport characteristics (N-polar HEMTs have a GaN channel layer on top of an AlGaN barrier layer, which is advantageous for reducing electron scattering and contact resistance), ② improved electric field distribution (N-polar structures are more advantageous for controlling electric field distribution than general Ga-polar structures, contributing to increased efficiency and reduced losses in high-voltage switching and power conversion devices), ③ reverse voltage blocking characteristics (N-polar GaN provides high-efficiency reverse voltage blocking capability, making it suitable for high-voltage operating environments required in power electronic devices), ④ ease of planar density control (in N-polar GaN, 2DEG density can be controlled more precisely depending on the AlGaN layer thickness, increasing design freedom), and ⑤ high performance realization due to polarity inversion (polarity inversion is combined with the ferroelectric properties of GaN in specific applications to achieve higher performance).

[0005] The present disclosure provides a method for forming a group 3 nitride semiconductor layer, wherein the polarity of the group 3 nitride semiconductor layer is N-polar.

[0006] This is described at the end of 'Specific details for implementing the invention'.

[0007] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.

[0008] According to one aspect of the present disclosure, a method for growing a group 3 nitride semiconductor layer is provided, comprising: a step of preparing a substrate; a step of forming a buffer layer on the substrate, wherein one of a GaN buffer layer and a sputtered AlN buffer layer is formed, wherein the GaN buffer layer is formed by growing the buffer layer using an MOCVD method at a growth temperature of 1000 to 1200°C, a growth pressure of 100 mbar or more (>100 mbar), and an atmosphere of H2 and N2; and a step of forming an N-polar group nitride semiconductor layer on the buffer layer, wherein the N-polar GaN is grown using an MOCVD method at a temperature of 1100 to 1200°C, a growth pressure of 200 mbar or more, and an atmosphere of H2 and N2.

[0009] This is described at the end of 'Specific details for implementing the invention'.

[0010] FIG. 1 is a drawing showing an example of a method for growing a group 3 nitride semiconductor layer as disclosed in U.S. Patent Publication No. 5,290,393.

[0011] FIG. 2 is a drawing showing a stack of group 3 nitride semiconductor layers according to the present disclosure,

[0012] FIGS. 3 and 4 are drawings illustrating an example of a method for growing a group 3 nitride semiconductor layer according to the present disclosure.

[0013] FIG. 5 is an etching test result for a group 3 nitride semiconductor layer according to the present disclosure,

[0014] FIG. 6 is a drawing showing an example of a semiconductor device to which a group 3 nitride semiconductor layer according to the present disclosure is applied.

[0015] The present disclosure will now be described in detail with reference to the accompanying drawings.

[0016] FIG. 2 is a drawing showing a stack of group nitride semiconductor layers according to the present disclosure, wherein the stack (A) comprises a substrate (10), a high-temperature growth buffer layer (20), and a group nitride semiconductor layer (30). The substrate (10) may be made of a heterogeneous substrate such as a sapphire substrate or a Si substrate, and is not particularly limited as long as the group nitride semiconductor layer (30) can be grown. Depending on what structure is grown on the group nitride semiconductor layer (30), various group nitride semiconductor layer structures such as diodes and transistors can be formed.

[0017] FIGS. 3 and FIGS. 4 are drawings illustrating an example of a method for growing a group 3 nitride semiconductor layer according to the present disclosure, FIG. 3 shows a method for growing a Ga-polar group 3 nitride semiconductor layer (30) as a comparative example, and FIG. 4 shows an example of a method for growing an N-polar group nitride semiconductor layer (30).

[0018] FIG. 3 presents four steps for growing a Ga-polar group 3 nitride semiconductor layer (30; e.g., GaN). The horizontal axis represents time (t), and the vertical axis represents temperature (T). Step (S1) is thermal cleaning, in which a substrate (10; e.g., a C-plane sapphire substrate) is cleaned at a temperature of approximately 1100–1200°C in an H2 atmosphere. Step (S2) is a step for growing a low-temperature buffer layer (LT-Buffer Layer), in which a buffer layer (20) is formed at a temperature of approximately 500–600°C in an H2 atmosphere. Step (S3) is a step for growing 3D (or Rough) GaN, in which GaN is grown at a temperature of approximately 1000–1100°C in an H2 atmosphere. Step (S4) is a step for growing 2D GaN, in which GaN is grown at a temperature of approximately 1100 to 1200°C in an H2 atmosphere. Through steps (S3) and (S4), a group nitride semiconductor layer (30; GaN) is grown, and Ga-polar GaN is formed under the given conditions. The MOCVD method is used as the growth method, TMGa is used as the Ga source, and NH3 is used as the N source. H2 is used as the carrier gas. Typically, the thickness of the buffer layer or seed layer (Necleation Layer) (20) is about 10 to 500 nm, and the group nitride semiconductor layer (30) is grown to have a thickness of about 3 to 5 μm.

[0019] FIG. 4 presents four steps for growing an N-polar group III nitride semiconductor layer (30; e.g., GaN). Step (S11) is identical to Step (S1). Unlike Step (S2), Step (S12) is a step for growing a high-temperature buffer layer (HT-Buffer Layer) or a seed layer (Nucleation Layer). A buffer layer (20) is formed at a temperature of 1000 to 1200°C, a growth pressure 50 to 80% higher (>100 mbar), and an atmosphere of H2:N2 = 10 to 50:50 to 90 using H2 and N2 as carrier gases. At this time, it is preferable to use a low V / III Ratio (<100). Steps (S13) and (S14), that is, the step of growing a group III nitride semiconductor layer (30), are carried out in an integrated manner, unlike steps (S3) and (S4), and GaN is grown at a temperature of 1100 to 1200°C, a high growth pressure (>200 mbar, preferably 300 to 600 mbar), and an atmosphere of H2:N2 = 10 to 50:50 to 90 using H2 and N2 as carrier gases. At this time, it is preferable to use a low NH3 flow rate (20 to 50% reduction compared to Normal) and a low TMGa flow rate (30 to 60% reduction compared to Normal) (V / III Ratio < 1000). N-polar GaN is formed under the presented conditions. In the presented example, steps (S12), (S13), and (S14) were carried out at the same growth temperature, but it is understood that they can be carried out at different temperatures within the above-mentioned range. The thickness of the buffer layer (20) and the thickness of the group 3 nitride semiconductor layer (30) can be the same as that of Ga-polar GaN. Instead of forming the buffer layer (20) with GaN using the MOCVD method, it can be formed with AlN using the sputtering method, which can be applied to both sapphire substrates and Si substrates, but has particular advantages when using a Si substrate.Sputtering conditions may include growth temperature: 500~700℃, growth gas 1 (Ar): 20~100 sccm, growth gas 2 (N2): 20~300 sccm, RF: 2000W (1000~3000), and DC: 300W (200~400).

[0020] In Fig. 5, it was confirmed that the group 3 nitride semiconductor layer grown through Figs. 3 and 4 is a semiconductor layer of different polarity. In the case of Ga-polar GaN, it is not etched by the etching solution, whereas in the case of N-polar GaN, it is etched by the etching solution, and this process is illustrated in Fig. 5.

[0021] FIG. 6 is a diagram showing an example of a semiconductor device to which a group 3 nitride semiconductor layer according to the present disclosure is applied, wherein the semiconductor device (B) may be a diode, a transistor, etc. This is Al x In y Ga 1-x-y It can be formed by doping a group 3 nitride layer made of N with a suitable dopant, such as Si or Mg, during the growth process. The illustration of the necessary etching and electrodes according to the specific device type is omitted. An example of an LED is presented in International Patent Publication WO2024 / 091031, and an example of a power device is presented in International Patent Publication WO2021 / 201580.

[0022] Various embodiments of the present disclosure are described below.

[0023] (1) A method for growing a group 3 nitride semiconductor layer, comprising: a step of preparing a substrate; a step of forming a buffer layer on the substrate, wherein the GaN buffer layer is grown using the MOCVD method at a growth temperature of 1000 to 1200°C, a growth pressure of 100 mbar or more (>100 mbar), and an atmosphere of H2 and N2; a step of forming an N-polar group nitride semiconductor layer on the buffer layer, wherein the N-polar GaN is grown using the MOCVD method at a temperature of 1100 to 1200°C, a growth pressure of 200 mbar or more, and an atmosphere of H2 and N2.

[0024] (2) A method for growing a group 3 nitride semiconductor layer in which the GaN buffer layer is grown at a V / III Ratio (<100) of 100 or less.

[0025] (3) A method for growing a group 3 nitride semiconductor layer, wherein a sputtered AlN buffer layer is used and the substrate is a Si substrate.

[0026] (4) A method for growing a group 3 nitride semiconductor layer, further comprising the step of forming a diode on the group 3 nitride semiconductor layer.

[0027] According to the group 3 nitride semiconductor light-emitting device and the method for emitting red light using the same according to the present disclosure, a group 3 nitride semiconductor light-emitting device emitting red light is substantially realized, and red light can be substantially emitted using the group 3 nitride semiconductor light-emitting device.

Claims

In a method for growing a group 1.3 nitride semiconductor layer, Step of preparing the substrate; A step of forming a buffer layer on a substrate, wherein one of a GaN buffer layer and a sputtered AlN buffer layer is formed, wherein the GaN buffer layer is grown using the MOCVD method at a growth temperature of 1000 to 1200°C, a growth pressure of 100 mbar or more (>100 mbar), and an atmosphere of H2 and N2; and, A method for growing a group nitride semiconductor layer, comprising: a step of forming an N-polar group nitride semiconductor layer on a buffer layer; wherein the N-polar GaN is grown using an MOCVD method at a temperature of 1100 to 1200°C, a growth pressure of 200 mbar or more, and an atmosphere of H2 and N2.

2. In Claim 1, A method for growing a group III nitride semiconductor layer, wherein the GaN buffer layer is grown at a V / III Ratio (<100) of 100 or less.

3. In Claim 1, A method for growing a group 3 nitride semiconductor layer, wherein a sputtered AlN buffer layer is used and the substrate is a Si substrate.

4. In Claim 1, A method for growing a group 3 nitride semiconductor layer, further comprising the step of forming a diode on the group 3 nitride semiconductor layer.

5. In Claim 2, A method for growing a group 3 nitride semiconductor layer, further comprising the step of forming a diode on the group 3 nitride semiconductor layer.

6. In Claim 3, A method for growing a group 3 nitride semiconductor layer, further comprising the step of forming a diode on the group 3 nitride semiconductor layer.

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