Method and apparatus for depositing Ga2O3 crystal film by HVPE method, and Ga2O3 crystal film deposition substrate obtained by using the same

Abstract

To require the development of a Ga2O3 epitaxial technique capable of diversifying a vapor deposition direction and minimizing surface defects.SOLUTION: Relating to a method for vapor depositing a Ga2O3 crystal film by the HVPE method, a vapor deposition apparatus and a Ga2O3 crystal-film vapor deposition substrate using the same, the method for vapor depositing a Ga2O3 crystal film comprises: the first step of supplying GaCl gas on a semiconductor single crystal substrate through a central supply passage; and the second step of supplying oxygen and HCl gas on the semiconductor single crystal substrate having the supplied GaCl gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for depositing a Ga2O3 crystal film by HVPE (hydride vapor phase epitaxy), and a Ga2O3 crystal film-deposited substrate obtained using the same, and more particularly to a method and apparatus for depositing a Ga2O3 crystal film with minimized surface defects, and a crystal film-deposited substrate obtained using the same. [Background technology]

[0002] Conventional Si-based power semiconductor devices have reached the limit of performance improvement compared to technological development due to the inherent limitations of their physical properties, and the industrial need for power semiconductor materials with WBG (Wide bandgap) and UWB (Ultra-wide bandgap) characteristics is increasing.

[0003] The manufacturing costs of UWB (ultra-wide bandgap) Ga2O3 material are approximately 1 / 3 to 1 / 5 of those of GaN or SiC, making it a price-competitive wafer for next-generation power semiconductors.

[0004] In particular, the Ga2O3 material for UWB can be grown thin, at about 1 / 3, to have the same breakdown voltage due to its breakdown voltage characteristics based on the bandgap, and it is not grown at high temperatures, which reduces the associated costs.

[0005] The epitaxial technique of Ga2O3 is a technique for growing a homogeneous β-Ga2O3 single crystal layer on a β-Ga2O3 substrate or an α-Ga2O3 single crystal layer on a foreign substrate such as sapphire, and includes a technique for obtaining a high-quality single crystal layer and a doping technique for obtaining n-type characteristics.

[0006] Ga2O3 material exists in four other phases (α, β, δ, ε) with β-Ga2O3 being the most stable form.

[0007] β-Ga2O3 is the most stable structure at high temperatures and is easy to grow ingots from, while the α-Ga2O3 phase is a relatively stable structure in the low temperature range below 500°C. The remaining phases all have meta-stable structures and exist in an unstable state.

[0008] β-Ga2O3 material has a band gap of approximately 4.8 to 4.9 eV, a monoclinic structure, and has large surface defects during deposition and cleavage characteristics, making surface processing difficult. For this reason, epitaxial technology development of Ga2O3 is being carried out to reduce surface defects in the grown epitaxial layer.

[0009] Recently, Japanese Patent Registration No. 6744523 (announced on August 4, 2020) proposed an invention for a method of growing in a direction that minimizes surface defects using the HVPE (Hydride Vapor Phase Epitaxy) method.

[0010] However, this method has a problem in that the deposition direction is limited to a specific direction, and therefore it is not possible to create a deposition surface with various crystal directions.

[0011] This calls for the development of Ga2O3 epitaxial technology that can diversify the deposition direction and minimize surface defects.

[0012] It should be noted that the above-mentioned background art is not necessarily publicly known art that was disclosed to the general public prior to the filing of the present application. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Registration No. 6744523 Summary of the Invention [Problem to be solved by the invention]

[0014] An object of one embodiment of the present invention is to provide a method and apparatus for depositing a Ga2O3 crystal film by a HVPE method, which can diversify the growth direction, thereby providing a high degree of freedom in the growth of the Ga2O3 crystal film and minimizing the number and depth of defects, and a deposition substrate for a Ga2O3 crystal film using the same. [Means for solving the problem]

[0015] As a technical means for achieving the above-mentioned technical object, according to one aspect of the present invention, a method for depositing a Ga2O3 crystal film by a HVPE method includes a first step of supplying GaCl gas through a central supply channel onto a semiconductor single crystal substrate, and a second step of supplying oxygen and HCl gas onto the semiconductor single crystal substrate to which the GaCl gas has been supplied.

[0016] According to one embodiment of the present invention, the HCl gas may be supplied through a bypass supply channel separate from a central supply channel.

[0017] According to one embodiment of the present invention, the HCl gas may be supplied together with nitrogen.

[0018] According to one aspect of the present invention, the HCl gas may be introduced at a flow rate of 10 sccm or more.

[0019] According to one embodiment of the present invention, the gas partial pressure of the HCl gas and the GaCl gas may be equal to or greater than 1:5.

[0020] According to one embodiment of the present invention, the gas partial pressure of the HCl gas and the GaCl gas may be equal to or greater than 2:5.

[0021] According to one embodiment of the present invention, a gas partial pressure of the GaCl gas and the HCl gas may be greater than 5:4.

[0022] According to one aspect of the present invention, the first step may include supplying HCl gas for reacting with gallium to the gallium at a flow rate of 50 sccm or more and 300 sccm or less.

[0023] According to another aspect of the present invention, a deposition apparatus for a Ga2O3 crystal film includes a central supply channel through which GaCl gas is supplied and connected to a reaction section, a bypass supply channel separated from the central supply channel, through which oxygen and HCl gas are supplied and connected to the reaction section, and the reaction section in which a Ga2O3 substrate is mounted.

[0024] According to another embodiment of the present invention, the central supply passage and the bypass supply passage can be controlled to a temperature of 450° C. or higher and 900° C. or lower.

[0025] According to another aspect of the present invention, the central supply channel and the bypass supply channel can be controlled so that the temperatures increase sequentially from the inlet to the zone where the GaCl gas evaporates and moves.

[0026] According to another aspect of the present invention, the central supply channel and the bypass supply channel are divided into an injection section, an evaporation section, and a transfer section from the inlet to a region where the GaCl gas evaporates and moves, and the injection section can be controlled at a temperature of 450°C to 650°C, the evaporation section can be controlled at a temperature of 550°C to 750°C, and the transfer section can be controlled at a temperature of 750°C to 900°C.

[0027] According to another aspect of the present invention, the reaction section can be controlled to a temperature of 850°C or higher and 1150°C or lower.

[0028] According to another aspect of the present invention, the reaction section is divided into an inlet section, a deposition section, and a discharge section from a section close to the central supply channel and the bypass supply channel to a section where the reactor body is discharged, and the inlet section may be controlled to 950°C or more and 1150°C or less, the deposition section may be controlled to 900°C or more and 1050°C or less, and the discharge section may be controlled to 850°C or more and 950°C or less.

[0029] According to yet another aspect of the present invention, the Ga2O3 thin film deposition substrate has a defect density of 4.57×10 4 / cm 2 It may be the following.

[0030] According to yet another aspect of the present invention, the thin film deposition substrate has a thickness of 100 g / cm 2 When the surface is polished by a chemical mechanical polishing (CMP) technique at a pressure of 1000 MPa for 180 minutes or less, all defects on the substrate surface can be polished away. In this case, for example, a silica slurry, a nanoceria slurry, or the like can be used as the CMP slurry.

[0031] According to yet another aspect of the present invention, the thin film deposition substrate may have a full width at half maximum (FWHM) value of the (002) and (-402) planes of 100 arcsec or less, an arithmetic mean roughness Ra of 300 nm or less, and a maximum profile height Rt of 2500 nm or less (JJIS B 0601-2001).

[0032] According to yet another aspect of the present invention, the thin film deposition substrate has a defect density of 2.29×10 4 / cm 2 or less, the full width at half maximum (FWHM) values ​​of the (002) and (-402) planes may be 100 arcsec or less, the surface roughness Ra may be 71 nm or less, and Rt may be 1150 nm or less.

[0033] According to yet another aspect of the present invention, the thin film deposition substrate has a defect density of 1.14×10 4 / cm 2 or less, the full width at half maximum (FWHM) values ​​of the (002) and (-402) planes may be 30 arcsec or less, the surface roughness Ra may be 11.42 nm or less, and Rt may be 203.20 nm or less. Effect of the Invention

[0034] According to any one of the above-mentioned means for solving the problems of the present invention, an embodiment of the present invention can provide a Ga2O3 deposited substrate having a deposition surface with minimized surface defects regardless of the deposition direction.

[0035] According to any one of the above-mentioned means for solving the problems of the present invention, one embodiment of the present invention can manufacture a substrate in which the time required for surface polishing (chemical-mechanical polishing (CMP)) after product deposition is minimized. [Brief description of the drawings]

[0036] [Figure 1] 1 is a flow chart of a Ga2O3 deposition method using an HVPE method according to an embodiment of the present invention. [Diagram 2] 1 is a conceptual diagram showing a deposition apparatus and a reaction process for performing a Ga2O3 deposition method by HVPE according to an embodiment of the present invention. [Diagram 3] 3 is a graph showing gas input flow rates for each line of the deposition apparatus of FIG. 2 according to an embodiment of the present invention. [Figure 4] 3 is a graph showing controlled temperatures for each block in the deposition apparatus of FIG. 2. [Diagram 5] This is a table listing optical microscope photographs taken at 50x, 200x, and 500x magnifications of the surfaces of the comparative examples and examples in Tables 1 and 2 of the main text. [Figure 6a] 1 is a graph showing the flow rate of HCl gas supplied to the bypass supply line and the full width at half maximum (FWHM) of the (002) plane and the (-402) plane. [Figure 6b] 1 is a graph showing the flow rate of HCl gas supplied to the bypass supply line and the resulting roughness (Ra, Rt) of the growth surface. [Figure 7] These are 50x optical microscope photographs of the surface, taken before and after surface polishing. [Figure 8] FIG. 1 is a schematic diagram showing the reaction process of a Ga2O3 deposition apparatus when an excess amount of HCl gas is introduced into the central supply channel. [Figure 9a] 1 is a graph showing the amount of HCl gas fed into the central supply channel and the growth rate of Ga2O3. [Figure 9b] 1 is a graph showing the flow rate of HCl gas supplied to the central supply channel and the full width at half maximum of the (002) plane and the (-402) plane. [Figure 10a] This is a photograph of the surface with X and Y marked on the deposition surface to define the X and Y directions. [Figure 10b] 1 is a graph comparing the surface roughness Ra and Rt in the X direction with the flow rate of HCl gas supplied to the central supply channel. [Figure 10c] 1 is a graph comparing the surface roughness Ra and Rt in the Y direction with the flow rate of HCl gas supplied to the central supply channel. [Figure 11] 1 is a table showing an example of a Ga2O3 deposition method by HVPE according to an embodiment of the present invention and a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In addition, in order to clearly explain the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are designated by similar reference numerals throughout the specification.

[0038] Throughout the specification, when a part is said to be "connected" to another part, this includes not only the case where the part is "directly connected" to another part, but also the case where the part is "indirectly connected" to another part through another element in between. Furthermore, when a part is said to "include" a certain component, this does not mean that the part excludes the other component, but that the part may further include the other component, unless otherwise specified.

[0039] The present invention will now be described in detail with reference to the accompanying drawings.

[0040] Fig. 1 is a flow chart of a Ga2O3 deposition method by HVPE according to an embodiment of the present invention, and Fig. 2 is a conceptual diagram showing a deposition apparatus and a reaction process for performing the Ga2O3 deposition method by HVPE according to an embodiment of the present invention. Fig. 3 is a graph showing a gas input flow rate for each line of the deposition apparatus of Fig. 2 according to an embodiment of the present invention. Fig. 4 is a graph showing a controlled temperature for each block in the deposition apparatus of Fig. 2.

[0041] The present invention will be described with reference to FIGS.

[0042] The method for depositing a Ga2O3 crystal film by the HVPE method includes a first step of supplying GaCl gas through a central supply channel onto a semiconductor single crystal substrate, and a second step of supplying oxygen and HCl gas onto the semiconductor single crystal substrate to which the GaCl gas has been supplied.

[0043] Here, HCl gas can be supplied along with nitrogen.

[0044] When deposition is performed, HCl gas can etch the high surface energy parts of the deposition surface. In this case, since the surface energy of the parts with a large curvature is high, the parts with a large curvature are selectively etched. Therefore, by adding HCl gas when deposition is performed, the parts with a large curvature can be minimized to form a deposition surface, and surface roughness can be reduced.

[0045] In the HVPE method, the raw material for vaporizing the raw material gallium is HCl gas. Since HCl gas is an oxidizing substance, HCl gas, which is the same substance, can be added during deposition.

[0046] When GaCl gas reacts with oxygen, the ratio of HCl gas to the reactant gas must be strictly maintained, so HCl gas may be supplied to a bypass supply channel separated from the central supply channel through which GaCl gas is supplied. Specifically, HCl gas may be supplied at a flow rate of 10 sccm or more.

[0047] Here, the ratio of the partial pressures of HCl gas and GaCl gas may be equal to or greater than 1:5, and preferably equal to or greater than 2:5. The reason why this value is effective will be described later with reference to FIG. 5 and Table 1.

[0048] If the ratio of the partial pressures of GaCl gas and HCl gas is less than 5:4, the deposition rate becomes excessively low, so it is preferable that the ratio is greater than 5:4.

[0049] This control method may be carried out in the deposition apparatus for Ga2O3 crystal film shown in FIG.

[0050] As shown in FIG. 2, the deposition apparatus for Ga2O3 crystal film according to the present invention includes a central supply channel 200 to which GaCl gas is supplied and connected to a reaction section, a bypass supply channel 210 separated from the central supply channel 200 to which oxygen and HCl gas are supplied and connected to the reaction section 220, and the reaction section 220 to which a Ga2O3 substrate is mounted, and further includes heaters 233, 235, 237, 243, 245, 247 to control the temperature of each reaction section.

[0051] The deposition apparatus for Ga2O3 crystal film according to an embodiment of the present invention is characterized in that source and reactant gases are supplied through separate supply paths, and in particular, HCl gas is further supplied through a separate bypass supply path 210.

[0052] A more detailed description will be given with reference to the graph of FIG. 3, which shows the flow rates of the individual components of the gas supplied to the central supply path 200 and the bypass supply path 210.

[0053] The contents of each column are as follows: "Individual Line" indicates the type of raw material supplied to each line. The unit of gas flow rate supplied to each line is sccm (Standard Cubic Centimeter per Minute). "Ratio of Flow (G1)" indicates the partial pressure of the total gas supply flow rate at the G1 stage where the deposition reaction actually occurs.

[0054] "Total Flow" shows the total flow rate for each stage, indicating the gas pressure of each line across the six stages that are commonly performed in the HVPE deposition process: loading, holding, substrate surface oxidation, GaCl gas preparation (Ga-T), deposition (G1), and unloading.

[0055] The gas supply behavior for each line is as follows.

[0056] The background nitrogen line (background N2: BG_N2) 301 supplies background nitrogen so that the gas does not flow back and a constant ratio is maintained even if a sudden change in gas partial pressure or the formation of a vortex occurs during the reaction. Nitrogen, which is an inert gas, can be supplied to both the central supply line 200 and the bypass supply line 210 at a ratio of 50% or more. The background nitrogen line 301 can maintain a constant value throughout the six stages.

[0057] Nitrogen, an inert gas, can be further supplied to the central supply channel 200. A balance nitrogen line (balance N2) 303 can supply balance nitrogen for fine adjustment of the internal pressure. Balance nitrogen can be further supplied for fine adjustment of the deposition surface quality. The deposition process can be performed with the balance nitrogen maintained at a constant value throughout the six stages and adjusted as necessary.

[0058] The bypass supply nitrogen line (O2_N2) 311 can supply nitrogen to the bypass supply path 210. The bypass supply path 210 is a supply path for supplying oxygen, but if only oxygen is supplied, there is a problem that it is difficult to maintain a uniform reaction rate in all regions. By mixing nitrogen, which is an inert gas, with oxygen, the oxygen can be diluted and supplied. The nitrogen supplied to the bypass supply path 210 can also be maintained at a constant value throughout the six stages.

[0059] The central supply nitrogen line (Ga_HCl_N2) 305 can supply nitrogen to the central supply channel 200. The central supply channel 200 is a reaction section where HCl gas reacts with gallium to form GaCl gas. Here, in order to control the reaction rate, it is necessary to dilute the HCl gas, and for this purpose, an inert gas is further supplied. The supplied nitrogen may be about 10 times the supplied HCl gas. The central supply nitrogen line 305 can maintain the supply flow rate of nitrogen at a constant value throughout the six stages.

[0060] In fact, the reactive gas is controlled differently for each step. In the sections (loading, holding) where the substrate is mounted and the gas flow is maintained, the reactive gases GaCl gas and oxygen are not supplied. During the substrate surface oxidation step, only oxygen is supplied to the bypass supply channel 210. In the GaCl gas preparation (Ga-T) step, HCl gas, which is a halogen acid, is supplied to the central supply channel 200 to maintain a uniform flow of GaCl gas. Then, in the deposition (G1) step where the reaction occurs, oxygen and HCl gas are supplied to the bypass supply channel 210, and GaCl gas is subsequently supplied to the central supply channel 200 to cause deposition. Then, in the unloading step, the supply of all reactive gases is stopped.

[0061] The process for each reactant gas supply line is as follows:

[0062] During the oxidation period G1 during deposition where a reaction occurs with the oxidation section that oxidizes the surface of the substrate, the oxygen line (O2) 315 supplies oxygen to the bypass supply path 210, and the supply of oxygen can be stopped for the remaining period. Although it depends on the type of substrate, if a surface polishing process is performed immediately before deposition, the oxide film on the surface may be removed, making surface deposition difficult. An oxidation period is placed before the G1 period, and oxygen is supplied onto the substrate for a certain period of time. When oxygen is supplied, an oxide film may form on the substrate surface. Thereafter, the supply of oxygen is stopped.

[0063] After the oxidation of the substrate is completed, in the GaCl gas preparation step, the central supply hydrochloric acid line (Ga_HCl) 307 can supply HCl gas to the central supply channel 200. Since this is a step to avoid unevenness in the time during which the initial reaction between HCl gas and gallium occurs, it does not matter if the amount of HCl gas supplied is less than the amount of GaCl gas supplied during deposition.

[0064] In the deposition step (G1), the central supply hydrochloric acid line 307 continues to supply HCl gas to the central supply passage 200, and the supply flow rate can be increased as necessary. In addition, the oxygen supply line 315 further supplies oxygen. If the oxygen supply is insufficient, the GaCl gas may not react sufficiently with the oxygen and may be exhausted as it is. In order to prevent waste of gallium raw material, oxygen may be supplied in excess of the GaCl gas. The HCl gas supplied to the central supply hydrochloric acid line 307 may be supplied at a partial pressure of about 5% compared to the oxygen.

[0065] During the G1 period when the reaction occurs, HCl gas is further supplied to the bypass supply line 210. HCl gas is also a raw material used to halogenate gallium, and has the advantage of being used as a single source. The bypass supply hydrochloric acid line (HCl) 313 can supply HCl gas at a rate of 1% or more compared to the amount of oxygen supplied in the G1 stage, and can supply HCl gas (Side_HCl) at a rate of 20% or more compared to the amount of HCl gas (Ga_HCl) supplied to the central supply hydrochloric acid line 307. The bypass supply hydrochloric acid line 313 can supply only to the G1 stage, and can stop supplying HCl gas during the remaining period.

[0066] As described above, by precisely controlling the ratio of GaCl gas supplied to the central supply path 200 and HCl gas supplied using the bypass supply path 210, a crystal film deposition process with reduced surface defects can be performed.

[0067] FIG. 4 is a graph showing controlled temperatures for each block in the manufacturing method of FIGS.

[0068] As shown in FIG. 2, the rear ends (downstream ends) of the central supply passage 200 and the bypass supply passage 210 are connected to the reaction section 220 .

[0069] In the central supply channel 200, HCl gas reacts with gallium to generate GaCl gas, and in the reaction section 220, GaCl gas reacts with oxygen. Since the raw materials supplied to the central supply channel 200 and the bypass supply channel 210 must be supplied to the reaction section 220 at similar temperatures (reaction temperatures), it is preferable that these supply channels 200 and 210 are heated together.

[0070] The central supply path 200 and the bypass supply path 210 are preferably controlled to a temperature between 450° C. and 900° C., which is an appropriate temperature for the reaction of HCl gas and gallium. The reaction part 220 is preferably controlled to a high temperature so that gallium chloride gas reacts with oxygen and defects are minimized during deposition. Specifically, the reaction part 220 is preferably controlled to a temperature between 850° C. and 1150° C. Since the control temperature of the reaction part 220 is higher than that of the central supply path 200 and the bypass supply path 210, it is preferable that the temperature is sequentially increased in the regions between the central supply path 200, the bypass supply path 210, and the reaction part 220.

[0071] Therefore, it is preferable that the central supply channel 200 and the bypass supply channel 210 are controlled so that the temperatures increase in sequence from the inlets to the zone where the GaCl gas evaporates and moves.

[0072] Specifically, the central supply path 200 and the bypass supply path 210 are divided into an injection section 233, an evaporation section 235, and a transfer section 237 from the inlet to the area where GaCl gas evaporates and moves, and the injection section 233 can be controlled to a temperature of 450°C or more and 650°C or less, the evaporation section 235 can be controlled to a temperature of 550°C or more and 750°C or less, and the transfer section 237 can be controlled to a temperature of 750°C or more and 900°C or less.

[0073] The reaction section 220 is also divided into an introduction section 243, a deposition section 245, and a discharge section 247 from the area close to the central supply path 200 and the bypass supply path 210 to the area where the reaction gas is discharged, and the introduction section 243 can be controlled to a temperature of 950°C or more and 1150°C or less, the deposition section 245 can be controlled to a temperature of 900°C or more and 1050°C or less, and the discharge section 247 can be controlled to a temperature of 850°C or more and 950°C or less.

[0074] FIG. 5 is a table listing surface photographs taken with an optical microscope at 50x, 200x, and 500x magnifications for the comparative examples and examples in Tables 1 and 2 of the main text.

[0075] No. 1 is a substrate without adding HCl gas (Side_HCl) to the bypass supply path, No. 2 is a substrate deposited by supplying HCl gas to the bypass supply path at a flow rate of 20 sccm, No. 3 is a substrate deposited by supplying HCl gas to the bypass supply path at a flow rate of 40 sccm, and No. 4 is a substrate deposited by supplying HCl gas to the bypass supply path at a flow rate of 60 sccm. This experiment is the result of an experiment in which growth was performed by changing only the flow rate of HCl gas supplied to the bypass supply path as a variable in the control graphs of Figures 3 and 4.

[0076] The growth conditions and surface property measurements are shown in [Table 1].

[0077] [Table 1]

[0078] Here, the roughness (Ra, Rt) was measured using a Dektak 150 surface inspection device (a stylus-type surface profilometer manufactured by ULVAC, Inc.), and the full width at half maximum of the rocking curve (FWHM of RC; in arc seconds) was measured using a Panalytical X'pert Pro MRD (high-resolution X-ray diffractometer) for each crystal plane (002, -402).

[0079] Comparing Comparative Example No. 1 with Examples No. 2 to No. 4, it can be seen that the surface roughness and full width at half maximum decrease as the flow rate of added HCl gas increases. Therefore, it can be seen that supplying a highly reactive gas and oxidizing and depositing GaCl gas in an oxidizing atmosphere (Examples No. 2 to No. 4) is more effective in reducing roughness and improving crystallinity than supplying GaCl gas and oxidizing it to deposit it (Comparative Example No. 1).

[0080] In the case of the average roughness, it is found that the average roughness drops significantly when the ratio of the amount of HCl gas (Ga_HCl) supplied to the central supply channel to the amount of HCl gas (Side_HCl) supplied to the bypass supply channel becomes 5:1 (No. 2), and the FWHM also becomes smaller, which has the effect of improving the crystallinity. When the ratio of the amount of HCl gas supplied to the central supply channel to the amount of HCl gas supplied to the bypass supply channel exceeds 5:2 (No. 3), the maximum roughness Rt also drops significantly. In addition, when the ratio of the amount of HCl gas supplied to the central supply channel to the amount of HCl gas supplied to the bypass supply channel exceeds 5:3 (No. 4), the crystallinity improves and both the maximum roughness and the average roughness are significantly reduced.

[0081] FIG. 6a is a graph showing the flow rate of HCl gas supplied to the bypass supply path and the full width at half maximum (FWHM) of the (002) and (-402) planes, and FIG. 6b is a graph showing the flow rate of HCl gas supplied to the bypass supply path and the resulting roughness Ra and Rt of the growth surface.

[0082] 6a and 6b are graphs showing the contents of Table 1. As can be seen from Table 1, when the flow rate of HCl gas applied to the bypass supply path exceeds 10 sccm, it can be confirmed that the crystallinity is greatly improved and the surface roughness is also greatly reduced.

[0083] Specifically, when 20 sccm or more of HCl gas is supplied to the bypass supply path (i.e., when the ratio of HCl gas (Side_HCl) supplied to the bypass supply path to HCl gas (Ga_HCl) supplied to the central supply path is 1:5 or more), it can be seen that the Ra value can be controlled to 300 nm or less and the FWHM value can be maintained at 100 arcsec or less.

[0084] In addition, as in No. 3, when 40 sccm or more of HCl gas is supplied to the bypass supply path (i.e., when the ratio of HCl gas (Side_HCl) supplied to the bypass supply path to HCl gas (Ga_HCl) supplied to the central supply path is 2:5 or more), it can be confirmed that the Rt value can be maintained at 1150 nm or less.

[0085] Also, when 60 sccm or more of HCl gas is supplied to the bypass supply path as in No. 4, the FWHM value is 30 arcsec or less, and the surface roughness Ra can be maintained at 11.42 nm or less, and Rt at 203.20 nm or less.

[0086] As can be seen from Table 1 and the photographs No. 1 to No. 4 in FIG. 5, the surface roughness tends to decrease as the flow rate of HCl gas supplied to the bypass supply line increases, and it can be seen that the roughness is significantly reduced compared to when no HCl gas is supplied at all (No. 1 in FIG. 5).

[0087] Specifically, when Ga2O3 is evaporated, a bend is generated in the direction in which the source gas for growth passes. The linear depression that occurs on the surface is called a peat.

[0088] Roughness can also be defined by counting the number of peats in an optical photograph magnified 500 times. Specifically, the number of peats was counted in an optical photograph taken of 241.4 μm × 181.1 μm, and the number of peats per unit area was shown in [Table 2].

[0089] [Table 2]

[0090] Among the examples, No. 2, which had the most peat, had 20% less peat than the comparative example No. 1, which made it easier to polish. 4 / cm 2 If it is smaller, even less polishing can remove the surface defect.

[0091] Preferably, the ratio of HCl gas supplied to the central supply line and the bypass supply line may be 10:4 or less and 10:6 or more. In this case, as shown in FIG. 6, the value of Rt is 1150 nm or less and the density of the peat is 2.29×10 4 / cm 2 The following can be maintained:

[0092] In addition, when the ratio of HCl gas supplied to the central supply line and the bypass supply line is 10:6 or more, the density of the peat is 1.14×10 4 / cm 2 The full width at half maximum of the (002) and (-402) planes can be kept at 30 arcsec or less, the surface roughness Ra can be kept at 11.42 nm or less, and the Rt can be kept at 203.20 nm or less.

[0093] FIG. 7 shows 50x optical microscope photographs of the surface observed before and after surface polishing.

[0094] Since the substrate surface immediately after deposition is rough, a subsequent deposition process can be performed only if the surface is polished to remove all defects. Here, the degree of surface polishing required is determined by the depth of the defects. In other words, the rough bends formed on the surface can be used as the surface for the subsequent deposition only if they are polished all the way to the deepest bends.

[0095] The substrate shown in FIG. 7 was polished using silica slurry as an abrasive at 100 g / cm 2The polishing was performed by applying a uniform pressure of 1000 MPa.

[0096] No. 2 is polished to the point where deposition is possible after polishing for 180 minutes.

[0097] No. 3 is polished to the point where deposition is possible after polishing for 120 minutes.

[0098] No. 4 is polished to the point where deposition is possible after polishing for 60 minutes.

[0099] In the case of Comparative Example No. 1, even when polished for 180 minutes or more under the same conditions, it is not polished to a level where deposition is possible (epi-ready), whereas the Example has the effect of significantly reducing the necessary polishing time.

[0100] Polishing must be performed until all bending disappears, so it is proportional to the Rt (maximum roughness) value. However, even if the maximum roughness is large, the required polishing time may differ depending on the roughness aspect. The effect of reducing roughness according to the present invention is not only to reduce the density of the peat, but also to reduce the required polishing time.

[0101] 8 to 10, the degree of optimization of the amount of HCl gas input into the central supply channel 200 will be confirmed.

[0102] FIG. 8 is a schematic diagram showing the reaction process of a Ga2O3 deposition apparatus when an excess amount of HCl gas is introduced into the central supply channel.

[0103] The configuration and heating method are the same as those in FIG. 2, but the amount of HCl gas fed into the central supply path 200 is changed instead of the flow rate of HCl gas fed into the bypass supply path 210 to minimize the roughness of the substrate.

[0104] Figure 9a is a graph showing the amount of HCl gas fed into the central supply channel and the growth rate of Ga2O3, and Figure 9b is a graph showing the flow rate of HCl gas fed into the central supply channel and the full width at half maximum of the (002) and (-402) planes. The unit of the full width at half maximum is arcsec.

[0105] When growing a crystal film, the flow rate of the HCl gas supplied to the central supply channel 200 is preferably greater than 50 sccm and equal to or less than 250 sccm.

[0106] When the HCl gas supplied to the central supply channel 200 is significantly increased, most of the HCl gas may react with gallium to generate GaCl gas. This GaCl gas reacts with an excess amount of oxygen to be deposited. Therefore, as shown in FIG. 9a, the growth rate is significantly increased. In particular, when the HCl gas is supplied to the central supply channel 200 at 250 sccm or more, the deposition rate of gallium oxide is significantly improved.

[0107] The increase in the FWHM indicates that various crystal structures are mixed. Referring to Fig. 9b, it can be seen that when HCl gas is supplied to the central supply channel 200 at a growth rate of 250 sccm or more, the crystal quality is rapidly degraded.

[0108] 9b, it can be seen that the full width at half maximum is smaller when 100 sccm of HCl gas is supplied than when 50 sccm of HCl gas is supplied. Therefore, supplying 100 sccm or more of HCl gas to the central supply channel 200 is more effective in improving crystallinity than supplying 50 sccm of HCl gas. Therefore, when growing a crystalline film, it is preferable that the flow rate of HCl gas supplied to the central supply channel 200 is greater than 50 sccm and is equal to or smaller than 250 sccm.

[0109] Fig. 10a is a photograph of a surface with X and Y marked on the deposition surface to define the X and Y directions, Fig. 10b is a graph comparing the surface roughness Ra and Rt in the X direction with the flow rate of HCl gas supplied to the central supply channel 200, and Fig. 10c is a graph comparing the surface roughness Ra and Rt in the Y direction with the flow rate of HCl gas supplied to the central supply channel 200. In each figure, the horizontal axis represents the flow rate of the supplied HCl gas, and the unit is sccm.

[0110] As shown in FIG. 10a, the same direction as the deposition gas supply direction is defined as Y, and the direction perpendicular to the deposition gas supply direction is defined as X.

[0111] When growing a crystalline film, the flow rate of the HCl gas supplied to the central supply channel 200, which can minimize roughness in the X-axis direction, is preferably greater than 50 sccm and equal to or less than 250 sccm.

[0112] 10b, it can be seen that the roughness in the X-axis direction decreases significantly when the flow rate of HCl gas supplied to the central supply channel 200 is less than 250 sccm. It can also be seen that the roughness temporarily decreases when the flow rate is greater than 50 sccm. Therefore, by maintaining the flow rate of HCl gas supplied to the central supply channel 200 greater than 50 sccm and equal to or less than 250 sccm, the roughness in the X-axis direction can be minimized.

[0113] In addition, when growing a crystal film, the flow rate of the HCl gas supplied to the central supply channel 200, which can minimize the roughness in the Y-axis direction, is preferably the same as or smaller than 250 sccm.

[0114] 10c, it can be seen that the roughness in the Y-axis direction is significantly reduced when the flow rate of HCl gas supplied to the central supply channel 200 is less than 250 sccm. Therefore, by maintaining the flow rate of HCl gas supplied to the central supply channel 200 at or below 250 sccm, the roughness in the Y-axis direction can be minimized.

[0115] 11 is a table showing an example of a Ga2O3 deposition method using the HVPE method according to an embodiment of the present invention and a comparative example. The serial numbers in the first column are experiment numbers.

[0116] The flow rate of HCl gas supplied to the central supply channel is preferably equal to or greater than 100 and equal to or less than 200. The most dominant factor in determining crystallinity and defects in deposition is the deposition rate, which depends on the amount of HCl gas supplied to the central supply channel. With reference to the experiments Nos. 2, 4, 6, 9, and 11 in this table, when HCl gas is supplied to the bypass supply channel at the same rate of 20 sccm, the crystallinity and roughness of the deposition surface can be compared with those of HCl gas supplied to the central supply channel.

[0117] It can be seen that when the flow rate of HCl gas supplied to the central supply channel is the same or smaller than 200 sccm, the crystallinity and roughness of the deposition surface are maintained almost unchanged, whereas when the flow rate exceeds 300 sccm, the crystallinity is significantly decreased and the roughness is significantly increased.

[0118] Furthermore, when no additional HCl gas is supplied to the bypass supply line, the crystallinity is low and the roughness is very high.

[0119] Therefore, the flow rate of HCl gas applied to the central supply path in the deposition process is preferably less than 300 sccm, and HCl gas is preferably further supplied to the bypass supply path.

[0120] According to the present invention, by supplying GaCl gas to the central supply channel and supplying oxygen and HCl gas onto the substrate on which deposition is to be performed, the crystallinity of the deposition surface can be improved and defects can be reduced.

[0121] According to the present invention, by maintaining the ratio of GaCl gas to HCl gas between 5:1 and 5:4, the growth rate can be maintained while minimizing defects on the deposition surface.

[0122] According to the present invention, the ratio of GaCl gas to HCl gas on the substrate to be deposited can be precisely controlled by supplying HCl gas to GaCl gas through a bypass supply path.

[0123] According to the present invention, the defect density of the deposition surface in the as-grown state is reduced to 4.57×10 4 / cm 2 By forming the following, the polishing time required to remove defects can be minimized.

[0124] The scope of the present invention is indicated by the claims set forth below rather than the above detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalents should be interpreted as being included within the scope of the present invention. [Explanation of symbols]

[0125] 200 Central supply route 210 Detour supply route 220 Reaction section 233 Injection part 235 Evaporation section 237 Transfer section 243 Transfer Department 245 Vapor deposition section 247 Emission part 301 Background Nitrogen Line 303 Balance Nitrogen Line 305 Central Nitrogen Supply Line 307 Central Supply Hydrochloric Acid Line 311 Bypass Nitrogen Supply Line 313 Bypass supply hydrochloric acid line 315 Oxygen Line

Claims

1. A first step of supplying GaCl gas onto a semiconductor single crystal substrate through a central supply channel; A second step of supplying oxygen and HCl gas onto the semiconductor single crystal substrate to which the GaCl gas has been supplied; The HCl gas is supplied through a bypass supply channel separated from the central supply channel, The method further includes, before the first step, supplying only oxygen onto the semiconductor single crystal substrate through the bypass supply path, and oxidizing the substrate surface. The ratio of the partial pressures of the HCl gas and the GaCl gas is equal to or greater than 1:

5. ２ O ３ Crystalline film deposition method.

2. 2. The Ga-Al-Ga-HVPE method according to claim 1, wherein the HCl gas is supplied together with nitrogen. ２ O ３ Crystalline film deposition method.

3. 2. The Ga ion implantation method according to claim 1, wherein the HCl gas is supplied at a flow rate of 10 sccm or more. ２ O ３ Crystalline film deposition method.

4. 2. The method for producing a GaAs layer by HVPE according to claim 1, wherein the ratio of partial pressures of the HCl gas and the GaCl gas is equal to or greater than 2:

5. ２ O ３ Crystalline film deposition method.

5. 5. The GaCl gas to HCl gas ratio according to claim 4, wherein the GaCl gas to HCl gas ratio is greater than 5:

4. ２ O ３ Crystalline film deposition method.

6. The first stage comprises:

2. The method of claim 1, further comprising the step of supplying HCl gas for reacting with gallium at a flow rate of 50 sccm to 300 sccm. ２ O ３ Crystalline film deposition method.

7. The central supply path and the bypass supply path are controlled so that the temperatures are sequentially increased from the inlet to the zone where the GaCl gas is evaporated and moved; The central supply path and the bypass supply path are divided into an injection section, an evaporation section, and a transfer section from the inlet to a region where the GaCl gas is evaporated and moved, The temperature of the injection section is controlled to be 450° C. or higher and 650° C. or lower. The evaporation section is controlled to a temperature of 550° C. or higher and 750° C. or lower. The Ga evaporation unit is controlled to a temperature of 750° C. or more and 900° C. or less. ２ O ３ Crystalline film deposition method.

8. a central supply channel through which GaCl gas is supplied and connected to the reaction section; a bypass supply channel separated from the central supply channel, through which oxygen and HCl gas are supplied and connected to the reaction unit; G ２ O ３ the reaction section to which a substrate is attached; The flow rates of the gases supplied through the central supply path and the bypass supply path are controlled so that the ratio of the partial pressures of the HCl gas and the GaCl gas is equal to or greater than 1:

5. ２ O ３ a control unit for controlling a substrate surface oxidation step of supplying only oxygen through the bypass supply path before a deposition step of forming a crystal film. ２ O ３ Crystalline film deposition equipment.

9. The GaAs according to claim 8, wherein the central supply path and the bypass supply path are controlled to have a temperature of 450° C. or higher and 900° C. or lower. ２ O ３ Crystalline film deposition equipment.

10. 10. The GaCl gas according to claim 9, wherein the central supply path and the bypass supply path are controlled so that the temperatures are increased sequentially from the inlet to the area where the GaCl gas is evaporated and moved. ２ O ３ Crystalline film deposition equipment.

11. The central supply path and the bypass supply path are divided into an injection section, an evaporation section, and a transfer section from the inlet to a region where the GaCl gas is evaporated and moved, The temperature of the injection section is controlled to be 450° C. or higher and 650° C. or lower. The evaporation section is controlled to a temperature of 550° C. or higher and 750° C. or lower. The evaporation section is controlled to have a temperature of 750° C. or higher and 900° C. or lower. ２ O ３ Crystalline film deposition equipment.

12. The reaction section is controlled to have a temperature of 850° C. or more and 1150° C. or less. ２ O ３ Crystalline film deposition equipment.

13. The reaction section is divided into an inlet section, a deposition section, and a discharge section from a section close to the central supply channel and the bypass supply channel to a section where a reaction gas is discharged, The temperature of the transfer section is controlled to be 950° C. or higher and 1150° C. or lower. The deposition section is controlled to a temperature of 900° C. or higher and 1050° C. or lower, The GaAs according to claim 11, wherein the temperature of the emission part is controlled to be 850° C. or more and 950° C. or less. ２ O ３ Crystalline film deposition equipment.

14. The defect density, as the number of peat defects per unit area, found on the substrate surface in the as-grown state is 4.57×10 ４ / cm ２ is as follows: The substrate surface has a surface roughness of 100 g / cm ２ When the surface of the substrate is polished by CMP at a pressure of 1000 MPa for 180 minutes or less, all defects on the substrate surface are polished away. ２ O ３ Crystalline film deposition substrate.

15. The defect density, as the number of peat defects per unit area, found on the substrate surface in the as-grown state is 4.57×10 ４ / cm ２ the substrate surface has a FWHM (full width at half maximum) value of 100 arcsec or less on the (002) and (-402) planes, a surface roughness Ra of 254.9 nm or less, and an Rt of 2312 nm or less. ２ O ３ Crystalline film deposition substrate.

16. The defect density, as the number of peat defects per unit area, found on the substrate surface in the as-grown state is 4.57×10 ４ / cm ２ the substrate surface has a defect density of 2.29×10 ４ / cm ２ The full width at half maximum of the (002) and (-402) planes is 90 arcsec or less, Ra is 71.5 nm or less, and Rt is 1150 nm or less. ２ O ３ Crystalline film deposition substrate.

17. The defect density, as the number of peat defects per unit area, found on the substrate surface in the as-grown state is 1.14×10 ４ / cm ２ Ga, characterized in that the full width at half maximum of the (002) and (-402) planes is 30 arcsec or less, the surface roughness Ra is 11.42 nm or less, and Rt is 203.20 nm or less. ２ O ３ Crystalline film deposition substrate.

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