Single epitaxial filling method for high-aspect-ratio groove

Abstract

The invention provides a single epitaxial filling method for a high-aspect-ratio groove, which comprises the following steps of: determining corresponding epitaxial deposition pressure according to the size relationship between epitaxial deposition temperature and groove deformation temperature, if the epitaxial deposition temperature is higher than the groove deformation temperature, the epitaxial deposition pressure is 150-400Torr, and if the epitaxial deposition temperature is lower than the groove deformation temperature, the epitaxial deposition pressure is 5-50Torr, the epitaxial deposition pressure is lower than the groove deformation temperature, and the epitaxial deposition pressure is lower than the groove deformation temperature. According to the method, the problems of cavity defects and groove deformation of the high-aspect-ratio groove in the epitaxial growth process can be solved, a single epitaxial filling method is adopted, the process is simple, and the growth efficiency is high.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and in particular to a single epitaxial filling method for a high aspect ratio trench. Background Art

[0002] Currently, shallow trench filling technology is relatively well established in semiconductor integrated circuit manufacturing. However, conventional filling methods are unable to achieve high-quality filling for trenches with high aspect ratios (aspect ratios greater than 5). Chemical vapor deposition (CVD), on the other hand, offers advantages such as high quality and easily controllable doping concentrations, making it suitable for filling high-aspect ratio trenches.

[0003] To meet the needs of further miniaturization and multifunctionality of electronic products, such as in the field of CMOS image sensors, with the increasing demand for high pixels and small size, the opening of the epitaxially grown trench structure in the pixel area of ​​the device is getting smaller and smaller, and the depth is getting deeper, with the aspect ratio reaching 10:1 or even 20:1 or above. However, the traditional CVD growth process will cause problems such as void defects and trench deformation. Figure 1 As shown, the void defect is generally located in the middle of the trench, and the trench deformation is generally located at the bottom of the trench. At present, a variety of solutions have been proposed to this problem. For example, CN114914191A discloses a method for epitaxial growth in a deep trench, which first repeats a low-pressure deposition-etching cycle of less than 30 Torr to make the epitaxial layer fill more than 2 / 3 of the depth of the deep trench. Subsequently, the low-pressure deposition-etching cycle can be continued, or a high-pressure deposition or high-pressure deposition-etching cycle of >30 Torr can be used (if necessary) until the epitaxial layer completely fills the entire depth of the deep trench. That is, this method fills the deep trench with the epitaxial layer by repeating the deposition-HCl etching cycle. For example, CN101752225A discloses a multi-level etching and filling method for ultra-deep trenches. This method decomposes the ultra-deep trenches into multi-level trenches from bottom to top, and the depth of each level of the trench is set at the depth allowed by the existing etching and epitaxial filling processes. The trench filling process is changed from CVD or PVD filling of polycrystalline silicon to epitaxial growth of single crystal silicon to improve the filling effect. That is, this method decomposes the deep trench into a multi-level structure for multi-level etching and multi-level epitaxial filling.

[0004] However, the traditional epitaxial growth process will cause the top of the trench to close and form a cavity inside due to the excessively fast top growth rate. In addition, the etched trench cannot maintain its original shape for a long time under high temperature (>800℃) / low pressure (<50Torr) conditions, and the Si atoms at the bottom of the trench will undergo thermal migration, resulting in deformation. Although existing technologies such as CN114914191A and CN101752225A have disclosed some solutions, they do not mention designing a reasonable solution for high reaction temperatures to reduce trench deformation. At the same time, the existing solution uses multiple depositions, and the overall efficiency is not high. Therefore, it is necessary to find a better solution that can be compatible with the existing process. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a single epitaxial filling method for high aspect ratio trenches. The corresponding epitaxial deposition pressure is determined according to the relationship between the epitaxial deposition temperature and the trench deformation temperature, thereby solving the problems of void defects and trench deformation in the epitaxial growth process of high aspect ratio trenches. Moreover, the present invention adopts a single epitaxial filling method with simple process and high growth efficiency.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The object of the present invention is to provide a single-shot epitaxial filling method for a high aspect ratio trench, the single-shot epitaxial filling method comprising the following contents:

[0008] S1: forming a high aspect ratio trench on a semiconductor substrate and determining the trench deformation temperature;

[0009] S2: Determine the epitaxial deposition temperature; if the epitaxial deposition temperature is greater than the trench deformation temperature, the epitaxial deposition pressure is 150 to 400 Torr; if the epitaxial deposition temperature is less than the trench deformation temperature, the epitaxial deposition pressure is 5 to 50 Torr;

[0010] According to the relationship between the epitaxial deposition temperature and the groove deformation temperature, the corresponding epitaxial deposition pressure is determined, and the epitaxial layer is deposited in the high aspect ratio groove until it is filled, thereby realizing single epitaxial filling.

[0011] It should be noted that if the epitaxial deposition temperature is greater than the trench deformation temperature, the epitaxial deposition pressure is 150-400 Torr, for example, 150 Torr, 180 Torr, 200 Torr, 230 Torr, 250 Torr, 280 Torr, 300 Torr, 320 Torr, 350 Torr, 380 Torr or 400 Torr.

[0012] It should be noted that if the epitaxial deposition temperature is less than the trench deformation temperature, the epitaxial deposition pressure is 5 to 50 Torr, for example, 5 Torr, 10 Torr, 15 Torr, 20 Torr, 25 Torr, 30 Torr, 35 Torr, 40 Torr, 45 Torr or 50 Torr.

[0013] The single-pass epitaxial filling method of the present invention determines the corresponding epitaxial deposition pressure based on the relationship between the epitaxial deposition temperature and the trench deformation temperature, thereby solving the problems of void defects and trench deformation in high aspect ratio trenches during epitaxial growth. Specifically, according to the molecular diffusion free path calculation formula, the lower the pressure, the longer the effective molecular diffusion distance. Therefore, when the epitaxial deposition temperature is less than the trench deformation temperature (for example, 800°C), low pressure (5-50 Torr) is used for deposition to improve deposition efficiency. In addition, at low temperatures, etching gas is easily adsorbed at the top of the trench, acting as a barrier site, reducing the enrichment of silicon source gas at the top, thereby diffusing to the bottom of the trench for filling. When the pressure is increased, the diffusion distance of the silicon source gas becomes shorter, so more etching gas is required. When the epitaxial deposition temperature is greater than the trench deformation temperature, the trench is easily deformed under low pressure, so a high-pressure (150-400 Torr) deposition process is adopted. In addition, the etching gas is easily decomposed at high temperature, the flow field response becomes better, and when the pressure increases, the overall HCl concentration increases, and the closure effect of the top of the barrier groove is better. Therefore, as the pressure increases, the amount of etching gas required decreases.

[0014] As a preferred technical solution of the present invention, in step S1, the aspect ratio of the high aspect ratio trench is greater than 10:1.

[0015] As a preferred technical solution of the present invention, in step S1, the groove deformation temperature is 780-800°C, for example, 780°C, 785°C, 790°C, 795°C or 800°C.

[0016] It should be noted that the trench deformation temperature refers to the deformation temperature of the semiconductor substrate with a high aspect ratio trench before epitaxial filling. The semiconductor substrate commonly used in the industry is the silicon substrate, and the plastic deformation starting temperature of the silicon substrate is generally 780-800°C. Therefore, the trench deformation temperature here is limited to 780-800°C, which has a wide range of applicability.

[0017] As a preferred technical solution of the present invention, in step S2, before depositing the epitaxial layer, hydrogen annealing is also included to remove the natural oxide layer.

[0018] As a preferred technical solution of the present invention, the annealing time of the hydrogen annealing is 1 to 10 minutes, for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes, etc., preferably 3 to 6 minutes.

[0019] Preferably, the annealing temperature of the hydrogen annealing is 850-1050°C, such as 850°C, 870°C, 900°C, 920°C, 950°C, 980°C, 1000°C, 1020°C or 1050°C, and preferably 950-1000°C.

[0020] Preferably, the annealing pressure of the hydrogen annealing is 200-600 Torr, for example, 200 Torr, 250 Torr, 300 Torr, 350 Torr, 400 Torr, 450 Torr, 500 Torr, 550 Torr or 600 Torr, and preferably 300-500 Torr.

[0021] It should be noted that the present invention preferably performs hydrogen annealing before depositing the epitaxial layer. By optimizing the temperature and pressure of the hydrogen annealing, the groove deformation during the removal of the natural oxide layer is improved. Specifically, the hydrogen annealing is performed under high temperature (>800°C) and high pressure (>200Torr) conditions. Because the thermal migration rate of silicon atoms is slowed down under high pressure, the groove deformation during the removal of the natural oxide layer is improved.

[0022] As a preferred technical solution of the present invention, in step S2, the epitaxial gas of the single epitaxial filling includes etching gas and silicon source gas, and the carrier gas of the single epitaxial filling includes H2.

[0023] As a preferred technical solution of the present invention, the etching gas includes Cl2 and / or HCl, preferably HCl.

[0024] Preferably, the silicon source gas includes any one of SiH4, SiH2Cl2 (DCS) or SiHCl3 (TCS) or a combination of at least two thereof, preferably SiH2Cl2 (DCS) and / or SiHCl3 (TCS).

[0025] As a preferred technical solution of the present invention, the etching gas is HCl; if the epitaxial deposition temperature is greater than the trench deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 2 to 15:1, for example, 2:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 13:1 or 15:1, etc., preferably 5 to 10:1; if the epitaxial deposition temperature is less than the trench deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 0.2 to 5:1, for example, 0.2:1, 0.5:1, 0.7:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1 or 5:1, etc., preferably 0.5 to 3:1.

[0026] As a preferred technical solution of the present invention, in the single epitaxial filling, the carrier gas flow rate is 10 to 80 slm, for example, 10 slm, 20 slm, 30 slm, 40 slm, 50 slm, 60 slm, 70 slm or 80 slm, etc., preferably 20 to 50 slm.

[0027] Preferably, in the single epitaxial filling, the silicon source gas flow rate is 50 to 300 sccm, for example, 50 sccm, 100 sccm, 150 sccm, 180 sccm, 200 sccm, 230 sccm, 250 sccm or 300 sccm, etc., preferably 150 to 250 sccm.

[0028] As a preferred technical solution of the present invention, in step S2, if the epitaxial deposition temperature is greater than the groove deformation temperature, the epitaxial deposition pressure is 150-250 Torr, for example, 150 Torr, 160 Torr, 170 Torr, 180 Torr, 190 Torr, 200 Torr, 210 Torr, 220 Torr, 230 Torr, 240 Torr or 250 Torr, etc.

[0029] As a preferred technical solution of the present invention, in step S2, if the epitaxial deposition temperature is less than the trench deformation temperature, the epitaxial deposition pressure is 10-30 Torr, for example, 10 Torr, 12 Torr, 15 Torr, 17 Torr, 20 Torr, 21 Torr, 23 Torr, 25 Torr, 26 Torr, 28 Torr or 30 Torr, etc.

[0030] Compared with the existing technical solutions, the present invention has at least the following beneficial effects:

[0031] (1) The present invention provides a single epitaxial filling method for high aspect ratio trenches. The corresponding epitaxial deposition pressure is determined according to the relationship between the epitaxial deposition temperature and the trench deformation temperature, thereby solving the void defects and trench deformation problems of high aspect ratio trenches during epitaxial growth. Moreover, the present invention adopts a single epitaxial filling method, which has a simple process and high growth efficiency.

[0032] (2) The present invention preferably performs hydrogen annealing before depositing the epitaxial layer, specifically by adopting high temperature (>800°C) and high pressure (>200Torr) conditions for hydrogen annealing, because the thermal migration rate of silicon atoms will slow down under high pressure, thereby improving the groove deformation during the removal of the natural oxide layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the void defects and trench deformation caused by the traditional CVD production process for high aspect ratio trenches;

[0034] Figure 2 It is a schematic flow chart of the single epitaxial filling method of the present invention;

[0035] Figure 3 This is a scanning electron microscope image of the high aspect ratio trench after filling in Example 1 of the present invention;

[0036] Figure 4 is a scanning electron microscope image of a high aspect ratio trench after filling in Example 2 of the present invention;

[0037] Figure 5 This is a scanning electron microscope image of the high aspect ratio trench after filling in Comparative Example 1 of the present invention;

[0038] Figure 6 This is a scanning electron microscope image of the high aspect ratio trench after filling in Comparative Example 2 of the present invention;

[0039] Figure 7 This is a correlation curve of the optimal etching gas flow rate and silicon source gas flow rate ratio at different epitaxial deposition temperatures when the epitaxial deposition pressure is fixed at 20 Torr;

[0040] Figure 8 This is a correlation curve of the optimal etching gas flow rate and silicon source gas flow rate ratio at different epitaxial deposition temperatures with a fixed epitaxial deposition pressure of 200 Torr;

[0041] Figure 9 This is a correlation curve of the optimal ratio of etching gas flow rate to silicon source gas flow rate under different epitaxial deposition pressures with a fixed epitaxial deposition temperature of 700°C;

[0042] Figure 10 It is a correlation curve diagram of the optimal etching gas flow rate and silicon source gas flow rate ratio under different epitaxial deposition pressures with a fixed epitaxial deposition temperature of 900°C. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0044] The present invention provides a single epitaxial filling method for a high aspect ratio trench. Figure 2 The single-shot epitaxial filling method of the present invention is shown as a flow chart. After forming a high-aspect-ratio trench on a silicon substrate, hydrogen annealing is first performed to remove the native oxide layer. Then, a reactive gas is introduced to deposit an epitaxial layer in the high-aspect-ratio trench until it is completely filled, thereby achieving single-shot epitaxial filling. Specifically, the single-shot epitaxial filling method includes the following steps:

[0045] S1: forming a high aspect ratio trench on a silicon substrate, wherein the aspect ratio of the high aspect ratio trench is greater than 10:1, and determining a deformation temperature of the trench, wherein the deformation temperature of the trench is 780-800° C.;

[0046] S2: Before depositing the epitaxial layer, hydrogen annealing is performed to remove the natural oxide layer; the annealing time of the hydrogen annealing is 1 to 10 minutes, preferably 3 to 6 minutes, the annealing temperature of the hydrogen annealing is 850 to 1050° C., preferably 950 to 1000° C., and the annealing pressure of the hydrogen annealing is 200 to 600 Torr, preferably 300 to 500 Torr;

[0047] Determine the epitaxial deposition temperature; if the epitaxial deposition temperature is greater than the groove deformation temperature, the epitaxial deposition pressure is 150 to 400 Torr, preferably 150 to 250 Torr; if the epitaxial deposition temperature is less than the groove deformation temperature, the epitaxial deposition pressure is 5 to 50 Torr, preferably 10 to 30 Torr;

[0048] According to the relationship between the epitaxial deposition temperature and the trench deformation temperature, the corresponding epitaxial deposition pressure is determined, and the epitaxial layer is deposited in the high aspect ratio trench until it is filled, thereby realizing single epitaxial filling; specifically, the epitaxial gas of the single epitaxial filling includes an etching gas and a silicon source gas, and the carrier gas of the single epitaxial filling includes H2; the etching gas includes Cl2 and / or HCl, preferably HCl; the silicon source gas includes any one of SiH4, SiH2Cl2 (DCS) or SiHCl3 (TCS) or a combination of at least two, preferably SiH2Cl2 (DCS) and / or SiHCl3 (TCS); further, the carrier gas flow rate is 10 to 80 slm, preferably 20 to 50 slm, and the silicon source gas flow rate is 50 to 300 sccm, preferably 150 to 250 sccm; the etching gas is HCl; if the epitaxial deposition temperature is greater than the groove deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 2 to 15:1, preferably 5 to 10:1; if the epitaxial deposition temperature is less than the groove deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 0.2 to 5:1, preferably 0.5 to 3:1.

[0049] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0050] Example 1

[0051] This embodiment provides a single-shot epitaxial filling method for a high aspect ratio trench, the single-shot epitaxial filling method comprising the following contents:

[0052] S1: forming a high aspect ratio trench on a silicon substrate, wherein the depth of the high aspect ratio trench is about 6.2 μm, the aspect ratio of the high aspect ratio trench is about 7:1, and the deformation temperature of the trench is determined to be 800° C.;

[0053] S2: Before depositing the epitaxial layer, hydrogen annealing is performed to remove the natural oxide layer; the annealing time of the hydrogen annealing is 5 minutes, the annealing temperature of the hydrogen annealing is 980° C., and the annealing pressure of the hydrogen annealing is 500 Torr;

[0054] The epitaxial deposition temperature is determined to be 700°C, and the epitaxial deposition temperature (700°C) satisfies the condition that the trench deformation temperature (800°C), so the epitaxial deposition pressure is selected to be 10 Torr; the etching gas in the epitaxial gas is HCl, the silicon source gas is SiH2Cl2 (DCS), H2 is used as the carrier gas, the carrier gas flow rate is 40 slm, the DCS flow rate is 225 sccm, the HCl flow rate is 125 sccm, and the ratio of HCl flow rate: silicon source gas flow rate is 0.56:1; the epitaxial layer is deposited in the high aspect ratio trench until it is filled, realizing single epitaxial filling.

[0055] Figure 3 The scanning electron microscope image of the high aspect ratio trench after filling in this embodiment is shown. It can be seen that the single epitaxial filling effect of this embodiment is good, and there are no void defects or trench deformation problems.

[0056] Example 2

[0057] This embodiment provides a single-shot epitaxial filling method for a high aspect ratio trench, the single-shot epitaxial filling method comprising the following contents:

[0058] S1: forming a high aspect ratio trench on a silicon substrate, wherein the depth of the high aspect ratio trench is about 6.2 μm, the aspect ratio of the high aspect ratio trench is about 7:1, and the deformation temperature of the trench is determined to be 800° C.;

[0059] S2: Before depositing the epitaxial layer, hydrogen annealing is performed to remove the natural oxide layer; the annealing time of the hydrogen annealing is 5 minutes, the annealing temperature of the hydrogen annealing is 980° C., and the annealing pressure of the hydrogen annealing is 500 Torr;

[0060] The epitaxial deposition temperature is determined to be 950°C, and the epitaxial deposition temperature (950°C) meets the requirement of epitaxial deposition temperature (950°C) > trench deformation temperature (800°C), so the epitaxial deposition pressure is selected to be 150 Torr; the etching gas in the epitaxial gas is HCl, the silicon source gas is SiH2Cl2 (DCS), H2 is used as the carrier gas, the carrier gas flow rate is 40 slm, the DCS flow rate is 225 sccm, the HCl flow rate is 2250 sccm, and the ratio of HCl flow rate: silicon source gas flow rate is 10:1; the epitaxial layer is deposited in the high aspect ratio trench until it is filled, realizing single epitaxial filling.

[0061] Figure 4 The scanning electron microscope image of the high aspect ratio trench after filling in this embodiment is shown. It can be seen that the single epitaxial filling effect of this embodiment is good, and there are no void defects or trench deformation problems.

[0062] Comparative Example 1

[0063] This comparative example provides a single epitaxial filling method for a high aspect ratio trench. Compared with Example 2, the only difference is that the epitaxial deposition pressure of 150 Torr is changed to 15 Torr, that is, the "epitaxial deposition temperature > trench deformation temperature, epitaxial deposition pressure is 150-400 Torr" is no longer satisfied.

[0064] Figure 5 The scanning electron microscope image of the high aspect ratio trench after filling in this comparative example is shown. It can be seen that the epitaxial filling effect in this comparative example is unsatisfactory. The results show that the Si atoms at the bottom of the trench undergo thermal migration, resulting in trench deformation.

[0065] Comparative Example 2

[0066] This comparative example provides a single epitaxial filling method for a high aspect ratio trench. Compared with Example 1, the only difference is that the epitaxial deposition pressure of 10 Torr is changed to 200 Torr, that is, the requirement of "epitaxial deposition temperature < trench deformation temperature, epitaxial deposition pressure of 5 to 50 Torr" is no longer met.

[0067] Figure 6 The scanning electron microscope image of the high aspect ratio trench after filling in this comparative example is shown. It can be seen that the epitaxial filling effect in this comparative example is unsatisfactory, and a void defect appears at a distance of nearly 5.48 μm from the top of the trench. The height of the void defect is nearly 1.18 μm. Moreover, the top of the trench is not completely filled, and a depression with a depth of nearly 736 nm appears at the top.

[0068] The following research is conducted on the optimal ratio of etching gas flow rate to silicon source gas flow rate:

[0069] Fixed conditions: forming a high aspect ratio trench on a silicon substrate, wherein the depth of the high aspect ratio trench is approximately 6.2 μm, the aspect ratio of the high aspect ratio trench is approximately 7:1, and the trench deformation temperature is determined to be 800°C; before depositing the epitaxial layer, hydrogen annealing is performed to remove the natural oxide layer; the annealing time of the hydrogen annealing is 5 minutes, the annealing temperature of the hydrogen annealing is 980°C, and the annealing pressure of the hydrogen annealing is 500 Torr; the etching gas in the epitaxial gas is HCl, and the silicon source gas is SiH2Cl2 (DCS), with H2 as the carrier gas, the flow rate of the silicon source gas is fixed, and the ratio of the etching gas flow rate to the silicon source gas flow rate is adjusted by adjusting the HCl flow rate; the optimal etching gas flow rate: silicon source gas flow rate ratio refers to: under different conditions, this flow rate ratio can achieve no void defects and trench deformation problems, which is obtained through experiments.

[0070] (1) The epitaxial deposition pressure is fixed at 20 Torr, and the optimal ratio of etching gas flow rate to silicon source gas flow rate at epitaxial deposition temperatures of 650℃, 700℃, 750℃, and 800℃ is explored. The relevant curves are shown in the figure below. Figure 7 shown.

[0071] (2) The epitaxial deposition pressure is fixed at 200 Torr, and the optimal ratio of etching gas flow rate to silicon source gas flow rate at epitaxial deposition temperatures of 800°C, 850°C, 900°C, 950°C, and 1000°C is explored. The relevant curves are shown in the figure below. Figure 8 shown.

[0072] (3) The epitaxial deposition temperature is fixed at 700 °C, and the optimal ratio of etching gas flow rate to silicon source gas flow rate is explored under epitaxial deposition pressures of 5 Torr, 10 Torr, 20 Torr, and 40 Torr. The relevant curves are shown in the figure below. Figure 9 shown.

[0073] (4) The epitaxial deposition temperature is fixed at 900 °C, and the optimal ratio of etching gas flow rate to silicon source gas flow rate is explored under epitaxial deposition pressures of 50 Torr, 100 Torr, 150 Torr, 200 Torr, and 300 Torr. The relevant curves are shown in the figure below. Figure 10 shown.

[0074] Figure 7 and Figure 8 It is explained that if the epitaxial deposition temperature is greater than the groove deformation temperature, the ratio of etching gas flow rate: silicon source gas flow rate is 2 to 15:1, preferably 5 to 10:1; if the epitaxial deposition temperature is less than the groove deformation temperature, the ratio of etching gas flow rate: silicon source gas flow rate is 0.2 to 5:1, preferably 0.5 to 3:1.

[0075] Figure 9 and Figure 10It is explained that if the epitaxial deposition temperature is less than the groove deformation temperature (for example, 800°C), low pressure (5-50 Torr) is used for deposition to improve the deposition efficiency. In addition, at low temperatures, the etching gas is easily adsorbed at the top of the groove, acting as a barrier site, reducing the enrichment of the silicon source gas at the top, thereby diffusing to the bottom of the groove for filling. When the pressure is increased, the diffusion distance of the silicon source gas becomes shorter, so more etching gas is required. When the epitaxial deposition temperature is greater than the groove deformation temperature, the groove is prone to deformation under low pressure, so a high pressure (150-400 Torr) deposition process is used. In addition, the etching gas is easy to decompose at high temperature, and the flow field response becomes better. When the pressure is increased, the overall HCl concentration increases, and the closure effect of the blocking groove top is better. Therefore, as the pressure increases, the amount of etching gas required decreases.

[0076] In summary, the present invention provides a single epitaxial filling method for high aspect ratio trenches. According to the relationship between the epitaxial deposition temperature and the trench deformation temperature, the corresponding epitaxial deposition pressure is determined, thereby solving the void defects and trench deformation problems of high aspect ratio trenches during the epitaxial growth process. Moreover, the present invention adopts a single epitaxial filling method with a simple process and high growth efficiency. The present invention preferably performs hydrogen annealing before depositing the epitaxial layer, specifically by adopting high temperature (>800°C) and high pressure (>200Torr) conditions for hydrogen annealing, because the thermal migration rate of silicon atoms will slow down under high pressure, thereby improving the trench deformation during the removal of the natural oxide layer.

[0077] While the present invention is described through the above-described embodiments to illustrate the detailed structural features of the present invention, the present invention is not limited to these detailed structural features, nor does it necessarily rely on these detailed structural features for implementation. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0078] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0079] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0080] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A single epitaxial filling method for a high aspect ratio trench, characterized in that: The single epitaxial filling method includes the following contents: S1: forming a high aspect ratio trench on a semiconductor substrate and determining the trench deformation temperature; S2: Determine the epitaxial deposition temperature; if the epitaxial deposition temperature is greater than the trench deformation temperature, the epitaxial deposition pressure is 150 to 400 Torr; If the epitaxial deposition temperature is less than the trench deformation temperature, the epitaxial deposition pressure is 5 to 50 Torr; According to the relationship between the epitaxial deposition temperature and the groove deformation temperature, the corresponding epitaxial deposition pressure is determined, and the epitaxial layer is deposited in the high aspect ratio groove until it is filled, thereby realizing single epitaxial filling.

2. The single epitaxial filling method according to claim 1, characterized in that: In step S1 , the aspect ratio of the high aspect ratio trench is greater than 10:

1.

3. The single epitaxial filling method according to claim 1, characterized in that: In step S1, the groove deformation temperature is 780-800°C.

4. The single epitaxial filling method according to claim 1, characterized in that: In step S2, before depositing the epitaxial layer, hydrogen annealing is also included to remove the natural oxide layer.

5. The single epitaxial filling method according to claim 1 or 4, characterized in that: In step S2, the epitaxial gas of the single epitaxial filling includes an etching gas and a silicon source gas, and the carrier gas of the single epitaxial filling includes H2.

6. The single epitaxial filling method according to claim 5, characterized in that: The etching gas comprises Cl2 and / or HCl, preferably HCl; Preferably, the silicon source gas includes any one of SiH4, SiH2Cl2 or SiHCl3 or a combination of at least two, preferably SiH2Cl2 and / or SiHCl3.

7. The single epitaxial filling method according to claim 6, characterized in that: The etching gas is HCl; if the epitaxial deposition temperature is greater than the groove deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 2 to 15:1, preferably 5 to 10:1; if the epitaxial deposition temperature is less than the groove deformation temperature, the ratio of HCl flow rate: silicon source gas flow rate is 0.2 to 5:1, preferably 0.5 to 3:

1.

8. The single epitaxial filling method according to claim 5, characterized in that: In the single epitaxial filling, the carrier gas flow rate is 10 to 80 slm, preferably 20 to 50 slm; Preferably, in the single epitaxial filling, the flow rate of the silicon source gas is 50 to 300 sccm, preferably 150 to 250 sccm.

9. The single epitaxial filling method according to claim 1, characterized in that: In step S2 , if the epitaxial deposition temperature is greater than the trench deformation temperature, the epitaxial deposition pressure is 150-250 Torr.

10. The single epitaxial filling method according to claim 1, characterized in that: In step S2 , if the epitaxial deposition temperature is less than the trench deformation temperature, the epitaxial deposition pressure is 10-30 Torr.

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