CN106876258A - The preparation method and its growth chamber structure of super uniform doping large area SiC epitaxial layer - Google Patents

Abstract

The invention discloses a method for preparing a super-doped uniform large-area SiC epitaxial layer and a growth chamber structure thereof. The preparation method of the super-doped homogeneous large-area SiC epitaxial layer adds two additional side inlet pipelines to the main inlet pipeline of the conventional LPCVD epitaxial growth source. The amount of input, combined with the structure of the rotating tray, can adjust the distribution of growth sources in the atmosphere on the entire large-area SiC epitaxial layer, thereby adjusting the proportion of growth sources in the atmosphere in the reaction chamber to adjust the doping concentration of the large-area SiC epitaxial layer. Thickness uniformity. The preparation method of the super-doped uniform large-area SiC epitaxial layer of the present invention can control the uniformity of the growth thickness of the large-area SiC epitaxial layer, thereby improving the uniformity of the growth thickness of the large-area SiC epitaxial layer, and can also control the growth of the large-area SiC epitaxial layer. The doping uniformity is controlled, thereby improving the doping concentration uniformity of the large-area SiC epitaxial layer.

Description

Preparation method and growth chamber of super-doped uniform large-area SiC epitaxial layer structure

Technical field:

The invention relates to the technical field of semiconductors, in particular to a method for preparing a super-doped uniform large-area SiC epitaxial layer and a growth chamber structure thereof.

Background technique:

Silicon carbide (SiC) material, as the third-generation wide-bandgap semiconductor, has excellent physical properties such as large bandgap, high temperature resistance, and radiation resistance, laying a good material foundation for the manufacture of power devices. Usually SiC devices are mainly fabricated on SiC epitaxial layers grown on SiC single crystal substrates. Because it is difficult to control doping during the growth of SiC single crystal, it is difficult to meet the requirements of device manufacturing. Although ion implantation can also achieve SiC doping, its effect is far from the precise control of doping obtained by CVD epitaxy. Therefore, the growth of SiC epitaxial layer material is an important and indispensable key technology in the manufacture of SiC devices.

The methods for preparing SiC epitaxial layer mainly include: sublimation method, liquid phase epitaxy method, sputtering method, pulsed laser deposition, molecular beam epitaxy and chemical vapor deposition method. At present, chemical vapor deposition method is the most widely used in commercial production.

The concentration doping uniformity and growth thickness uniformity of SiC epitaxial materials seriously affect the performance of SiC devices. Good material uniformity can not only reduce the dispersion of device performance, but also improve the reliability of devices.

With the continuous development of the SiC industry, the development trend of the SiC epitaxial layer tends to be larger. The large-area SiC epitaxial layer has a larger area available for device preparation, which can effectively reduce the waste of materials. However, as the size of the SiC substrate continues to increase, the requirements for doping concentration and growth thickness control in the SiC epitaxial layer also increase accordingly. How to improve the thickness and concentration uniformity of the large-area SiC epitaxial layer is a SiC epitaxy. Breakthrough and key technologies mastered.

Due to the different depletion methods of various growth sources along the gas flow direction in the reaction chamber, the doping concentration uniformity and growth thickness uniformity of the SiC epitaxial layer are also different, and the doping concentration uniformity of the large-area SiC epitaxial layer and growth thickness uniformity for different depletions. The depletion of the growth source gas in the diameter direction of the epitaxial layer causes the growth rate and doping concentration of local points on the epitaxial layer to vary with the position, thus causing the inhomogeneity of the epitaxial thickness and concentration. Due to the different depletion forms of various growth sources in the reaction chamber, generally speaking, there are three main forms of depletion (ideal state): 1. Linear depletion; 2. Exponential depletion; 3. Quadratic function type exhausted. The inhomogeneity of the source distribution caused by the linear depletion of the gas source can be reduced by introducing the tray, but in the latter two depletion modes, the tray cannot completely eliminate the inhomogeneity of the source distribution, especially because there are large The inhomogeneity of doping concentration and thickness caused by temperature gradient.

In view of this, the inventor proposes the following technical solutions.

Invention content:

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a method for preparing a super-doped uniform large-area SiC epitaxial layer.

In order to solve the above-mentioned technical problems, the present invention adopts the following first technical solution: the preparation method of the super-doped uniform large-area SiC epitaxial layer adds two additional side intake pipes to the main intake pipeline of the conventional LPCVD epitaxial growth source By adjusting the type and amount of growth sources fed into the two side inlet pipes, combined with the rotating tray structure, the distribution of growth sources in the atmosphere on the entire large-area SiC epitaxial layer is adjusted, thereby adjusting the atmosphere in the reaction chamber The ratio of the growth source in to adjust the doping concentration and thickness uniformity of the large-area SiC epitaxial layer.

Further, in the above technical solution, the passage of the main air intake pipeline is trumpet-shaped, the two side air intake pipelines communicate with the rear end of the passage of the main air intake pipeline, and the growth source inlet of the two side air intake pipelines leads into The growth source includes doping source, C source, Si source, carrier gas, etching gas, the doping source includes N ₂ , Al(CH ₃ ) ₃ , the C source includes C ₂ H ₄ , C ₃ H ₈ , Si The source includes Si ₂ H ₄ , SiHCl ₃ , the carrier gas includes H ₂ , Ar ₂ , and the etching gas includes HCl.

Further, in the above technical solution, the two side air inlet pipelines lead into the Si source to increase the ratio of the C source to the Si source in the atmosphere of the side reaction chamber, reduce the N-type doping concentration or increase the P-type doping concentration , so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer.

Further, in the above technical solution, the two side air inlet pipelines lead into the C source to reduce the ratio of the C source to the Si source in the atmosphere of the reaction chamber, increase the N-type doping concentration or reduce the P-type doping concentration, In this way, the uniformity of the doping concentration of the large-area SiC epitaxial layer can be adjusted.

Furthermore, in the above-mentioned technical solution, the two side air inlet pipelines are fed into the Si source and the C source at the same time to increase the concentration of the C source and the Si source in the atmosphere of the reaction chamber, so as to increase the growth rate of the SiC epitaxial layer, so as to achieve Adjustment of thickness uniformity of large area SiC epitaxial layer growth.

Furthermore, in the above-mentioned technical solution, the two side air inlet pipelines are fed with carrier gas to dilute the concentration of C source and Si source in the atmosphere of the reaction chamber, and reduce the growth rate of the SiC epitaxial layer, thereby achieving the goal of large-area SiC epitaxy. Adjustment of layer growth thickness uniformity.

Furthermore, in the above technical solution, the two side air inlet pipelines are connected with N sources to increase the N-type doping concentration on the side, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer; The Al source can increase the P-type doping concentration on the side, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer.

Furthermore, in the above technical solution, the two side gas inlet pipes are fed with etching gas to slightly reduce the growth rate of the SiC epitaxial layer, so as to achieve fine adjustment of the uniformity of the growth thickness of the large-area SiC epitaxial layer.

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a large-area SiC epitaxial layer growth chamber structure with super-doping uniformity.

In order to solve the above-mentioned technical problems, the present invention adopts the following second technical scheme: the super-doped uniform large-area SiC epitaxial layer growth chamber structure includes: a silicon carbide LPCVD reaction chamber, and the outer side of the silicon carbide LPCVD reaction chamber It is provided with a heating assembly for heating it; a tray, which is located in the silicon carbide LPCVD reaction chamber, is provided with a carrying tank to carry a large-area SiC wafer; a three-way gas guide pipeline structure, which is installed in the silicon carbide LPCVD reaction chamber On the side of the inlet end of the chamber, the three-way gas guide pipeline structure is composed of a main gas pipeline connected with the silicon carbide LPCVD reaction chamber and two side gas guide pipelines located on both sides of the main gas pipeline and isolated from each other; the three-way inlet The air pipeline structure is connected with the three-way air guide pipeline structure, and the three-way air intake pipeline structure includes a pipe main body, a main air intake pipeline formed at the front end of the pipe main body, and two side air intake pipelines respectively located on both sides of the main air intake pipeline. The air intake pipeline, the main air intake pipeline and the two side air intake pipelines are all in communication with the inner cavity of the main body of the pipe, and the inner cavity of the main body of the pipe is connected with the main air intake pipeline and the side air guide pipeline; the side air intake pipeline and the main air intake pipeline pass through An inclined plane is connected so that the main air intake pipeline and the inner cavity of the pipe main body form a trumpet-shaped passage, and communicate with the main air pipeline and the side air guide pipeline.

Further, in the above technical solution, the main air intake line corresponds to the main air intake line, and the size of the main air intake line is larger than that of the main air intake line; the side air intake line corresponds to the side air guide line, and the side air intake line corresponds to the side air guide line The size of the intake line is smaller than the size of the side air line.

After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

1. The method for preparing a large-area SiC epitaxial layer with super-doped uniformity of the present invention can control the uniformity of the growth thickness of the large-area SiC epitaxial layer, thereby improving the uniformity of the growth thickness of the large-area SiC epitaxial layer, and can also control the growth thickness uniformity of the large-area SiC epitaxial layer. The doping uniformity of the layer (wafer) is controlled, thereby improving the doping concentration uniformity of the large-area SiC epitaxial layer.

2. The large-area SiC epitaxial layer growth chamber of the present invention has a simple structure and can effectively adjust the proportion of growth sources in the atmosphere in the reaction chamber to adjust the doping concentration and thickness uniformity of the large-area SiC epitaxial layer .

Description of drawings:

Fig. 1 is a schematic diagram of the distribution of SiC epitaxial layer thickness along the radial direction obtained by conventional methods;

Fig. 2 is the distribution along the radial direction of the SiC epitaxial layer thickness obtained by the inventive preparation method;

Fig. 3 is the distribution of SiC epitaxial layer doping concentration along the radial direction obtained by conventional methods;

Fig. 4 is the distribution along the radial direction of the doping concentration of the SiC epitaxial layer obtained by the inventive preparation method;

Fig. 5 is a schematic diagram of the structure of the invention super-doped uniformity large-area SiC epitaxial layer growth chamber structure;

Fig. 6 is a structural schematic diagram of the three-way gas guide pipeline structure in the large-area SiC epitaxial layer growth chamber structure of the invention of super-doping uniformity;

Fig. 7 is a structural schematic diagram of the three-way inlet pipeline structure in the chamber structure of the invention for the growth of the large-area SiC epitaxial layer with super-doping uniformity.

detailed description:

The present invention will be further described below in conjunction with specific embodiments and accompanying drawings.

The preparation method of the super-doped uniform large-area SiC epitaxial layer of the present invention, the method adds two additional side intake pipelines to the main intake pipeline of the conventional LPCVD epitaxial growth source, and adjusts the growth rate of the two side intake pipelines. The source type and the size of the input, combined with the rotating tray structure, can adjust the growth source distribution in the atmosphere on the entire large-area SiC epitaxial layer, thereby adjusting the proportion of the growth source in the atmosphere in the reaction chamber to adjust the large-area SiC epitaxial layer. Doping concentration and thickness uniformity. Wherein, the passage of the main air intake pipeline is trumpet-shaped, and the two side air intake pipelines communicate with the rear end of the passage of the main air intake pipeline.

The growth sources introduced by the growth source inlets of the two side air intake pipelines include doping sources, C sources, Si sources, carrier gases, and etching gases. The doping sources include N ₂ , Al(CH ₃ ) ₃ , and the C sources include C ₂ H ₄ , C ₃ H ₈ , the Si source includes Si ₂ H ₄ , SiHCl ₃ , the carrier gas includes H ₂ , Ar ₂ , and the etching gas includes HCl.

The Si source is fed into the two side air intake lines to increase the ratio of the C source and the Si source in the atmosphere of the side reaction chamber, reduce the N-type doping concentration or increase the P-type doping concentration, so as to achieve a large-area SiC epitaxial layer Adjustment of doping concentration uniformity.

The two side air intake pipelines lead to the C source to reduce the ratio of the C source and the Si source in the atmosphere of the reaction chamber, increase the N-type doping concentration or reduce the P-type doping concentration, so as to achieve the purpose of doping the large-area SiC epitaxial layer. Adjustment of impurity concentration uniformity.

The Si source and the C source are fed into the two side air intake lines at the same time to increase the concentration of the C source and the Si source in the atmosphere of the reaction chamber, so as to increase the growth rate of the SiC epitaxial layer, so as to achieve a uniform growth thickness of the large-area SiC epitaxial layer sexual adjustment.

Carrier gas is fed into the two side air intake lines to dilute the concentration of C source and Si source in the atmosphere of the reaction chamber, and reduce the growth rate of the SiC epitaxial layer, so as to achieve the adjustment of the uniformity of the growth thickness of the large-area SiC epitaxial layer.

The two side air inlet pipelines are fed with N sources to increase the N-type doping concentration on the side, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer; the Al sources on both sides can increase the side P-type doping Doping concentration, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer.

The N source is N ₂ , and the Al source is Al(CH ₃ ) ₃ .

The two side gas inlet pipelines are fed with etching gas to slightly reduce the growth rate of the SiC epitaxial layer, so as to achieve fine adjustment of the uniformity of the growth thickness of the large-area SiC epitaxial layer.

In summary, as described in conjunction with Figures 1-4, compared with conventional methods, the method for preparing a large-area SiC epitaxial layer with hyper-doped uniformity in the present invention can control the growth thickness uniformity of large-area SiC epitaxy, thereby improving The uniformity of the growth thickness of the large-area SiC epitaxial layer can also control the doping uniformity of the large-area SiC epitaxial layer (wafer), thereby improving the uniformity of the doping concentration of the large-area SiC epitaxial layer.

As shown in Figures 5-7, it is a super-doped uniform large-area SiC epitaxial layer growth chamber structure for the above method, which includes: a silicon carbide LPCVD reaction chamber 1, a silicon carbide LPCVD reaction chamber The tray 2 in 1 and used to carry the large-area SiC wafer 22, the three-way gas guide pipeline structure 3 installed on the side of the silicon carbide LPCVD reaction chamber 1, and the three-way air intake pipeline connected to the three-way gas guide pipeline structure 3 Structure 4, the silicon carbide LPCVD reaction chamber 1 is provided with a heating assembly for heating it.

The tray 2 is provided with a carrying slot 21 for carrying a large-area SiC wafer 22, and the tray 2 can be rotated evenly.

The three-way gas guide pipeline structure 3 is composed of a main gas guide pipeline 31 communicating with the SiC LPCVD reaction chamber 1 and two side gas guide pipelines 32 located on both sides of the main gas pipeline 31 and isolated from each other.

The three-way air intake pipeline structure 4 includes a pipe main body 41, a main air intake pipeline 42 formed at the front end of the pipe main body 41, and two side air intake pipelines 43 respectively located on both sides of the main air intake pipeline 42. The main air intake pipeline 42 and two side air intake pipelines 43 are all communicated with the inner cavity of the pipe main body 41, and the inner cavity of the pipe main body 41 communicates with the main air guide pipeline 31 and the side air guide pipeline 32; the main air intake pipeline 42 corresponds to the main air guide pipeline 31, And the size of the main air intake pipeline 42 is larger than that of the main air intake pipeline 31;

The side air intake pipeline 43 is connected to the main air intake pipeline 42 through an inclined plane, so that the main air intake pipeline 42 and the inner cavity of the main body 41 form a trumpet-shaped passage, and communicate with the main air intake pipeline 31 and the side air guide pipeline 32 , the reaction source flows into the silicon carbide LPCVD reaction chamber 1 from the three-way gas guide pipe structure 3 uniformly in an equal proportion after passing through the three-way air intake pipeline structure 4, thereby adjusting the proportion of the growth source in the atmosphere in the reaction chamber to Adjust the doping concentration and thickness uniformity of the large-area SiC epitaxial layer.

The super-doped uniformity large-area SiC epitaxial layer growth chamber of the present invention has a simple structure, and can effectively adjust the proportion of growth sources in the atmosphere in the reaction chamber to adjust the doping concentration and thickness uniformity of the large-area SiC epitaxial layer.

Of course, the above descriptions are only specific embodiments of the present invention, and are not intended to limit the implementation scope of the present invention. All equivalent changes or modifications made according to the structure, features and principles described in the scope of the patent application of the present invention should be included in the The present invention is within the patent scope.

Claims (10)

1. The preparation method of super-doped uniform large-area SiC epitaxial layer is characterized in that: this method adds two additional side air intake lines to the main air intake line of the conventional LPCVD epitaxial growth source, by adjusting the two side air intake lines The type of growth source and the size of the input, combined with the rotating tray structure, can adjust the distribution of growth sources in the atmosphere on the entire large-area SiC epitaxial layer, thereby adjusting the proportion of growth sources in the atmosphere in the reaction chamber to adjust the large area. Area SiC epitaxial layer doping concentration and thickness uniformity. 2. The method for preparing a large-area SiC epitaxial layer with super-doped uniformity according to claim 1, characterized in that: the channel of the main air intake line is trumpet-shaped, and the two side air intake lines are connected to the main air intake line In the rear part of the channel, the growth sources introduced by the growth source inlets of the two side air intake pipelines include doping sources, C sources, Si sources, carrier gases, and etching gases. The doping sources include _N2 , Al( CH ₃ ) ₃ , the C source includes C ₂ H ₄ , C ₃ H ₈ , the Si source includes Si ₂ H ₄ , SiHCl ₃ , the carrier gas includes H ₂ , Ar ₂ , and the etching gas includes HCl. 3. the preparation method of super-doped uniformity large-area SiC epitaxial layer according to claim 2, is characterized in that: two side gas inlet pipelines lead into Si source, to promote the C source in the side reaction chamber atmosphere and The ratio of the Si source can reduce the N-type doping concentration or increase the P-type doping concentration, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer. 4. The method for preparing a large-area SiC epitaxial layer with super-doped uniformity according to claim 2, characterized in that: two side air intake pipelines lead into the C source to reduce the C source and Si in the atmosphere of the reaction chamber. Ratio of the source, increase the N-type doping concentration or reduce the P-type doping concentration, so as to achieve the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer. 5. The method for preparing a large-area SiC epitaxial layer with super-doped uniformity according to claim 2, characterized in that: two side air intake pipelines feed Si source and C source simultaneously to increase the C in the atmosphere of the reaction chamber. source and the concentration of Si source to increase the growth rate of the SiC epitaxial layer, so as to achieve the adjustment of the uniformity of the growth thickness of the large-area SiC epitaxial layer. 6. The preparation method of super-doped homogeneous large-area SiC epitaxial layer according to claim 2, characterized in that: the two side air intake pipelines feed carrier gas to dilute the C source and Si source in the atmosphere of the reaction chamber concentration, reduce the growth rate of the SiC epitaxial layer, so as to achieve the adjustment of the uniformity of the growth thickness of the large-area SiC epitaxial layer. 7. The method for preparing a large-area SiC epitaxial layer with super-doped uniformity according to claim 2, characterized in that: two side air intake pipelines lead into N sources to increase the N-type doping concentration of the side, so as to achieve Adjustment of the uniformity of doping concentration of the large-area SiC epitaxial layer; the introduction of Al sources on both sides can increase the P-type doping concentration of the side, thereby achieving the adjustment of the uniformity of the doping concentration of the large-area SiC epitaxial layer. 8. The preparation method of super-doped homogeneous large-area SiC epitaxial layer according to claim 2, characterized in that: the two side gas inlet pipelines lead into etching gas to slightly reduce the growth rate of SiC epitaxial layer, so as to achieve Fine-tuning of thickness uniformity in the growth of large-area SiC epitaxial layers. 9. A super-doped uniform large-area SiC epitaxial layer growth chamber structure, characterized in that: it includes: A silicon carbide LPCVD reaction chamber (1), the outer side of the silicon carbide LPCVD reaction chamber (1) is provided with a heating assembly for heating it; A tray (2), which is located in the silicon carbide LPCVD reaction chamber (1), on which a carrying slot (21) is provided to carry a large-area SiC wafer (22); The three-way gas guide pipeline structure (3) is installed on the side of the inlet end of the silicon carbide LPCVD reaction chamber (1), and the three-way gas guide pipeline structure (3) is communicated with the silicon carbide LPCVD reaction chamber (1) The main gas pipeline (31) and two side gas pipelines (32) that are located on both sides of the main gas pipeline (31) and are isolated from each other are formed; The three-way air intake pipeline structure (4) is connected to the three-way air guide pipeline structure (3), and the three-way air intake pipeline structure (4) includes a pipe main body (41) and is formed on the front end of the pipe main body (41). The main air intake pipeline (42) and two side air intake pipelines (43) respectively located on both sides of the main air intake pipeline (42), the main air intake pipeline (42) and the two side air intake pipelines (43) are all connected with The inner cavity of the tube main body (41) is connected, and the inner cavity of the tube main body (41) is connected with the main air guide line (31) and the side air guide line (32); between the side air intake line (43) and the main air intake line (42) It is connected by an inclined plane, so that the main air intake pipeline (42) and the inner cavity of the pipe main body (41) form a trumpet-shaped channel, and communicate with the main air pipeline (31) and the side air guide pipeline (32). 10. A super-doped uniform large-area SiC epitaxial layer growth chamber structure according to claim 9, characterized in that: the main gas inlet pipeline (42) corresponds to the main gas pipeline (31), and the main The size of the air intake pipeline (42) is greater than the size of the main air intake pipeline (31); the side air intake pipeline (43) corresponds to the side air guide pipeline (32), and the size of the side air intake pipeline (43) is smaller than that of the side air guide pipeline. The size of the gas pipeline (32).