Silicon carbide epitaxial deposition equipment and base assembly thereof

Abstract

The utility model provides silicon carbide epitaxial deposition equipment and a base assembly thereof. The base assembly comprises a substrate tray, the central area of the substrate tray is provided with a concave pit, and the concave pit is used for containing a substrate; the upper part of the rotating cylinder supports the substrate tray, and the rotating cylinder is connected with a purging gas supply unit; the heater is made of graphite and is arranged in the rotating cylinder; and gas in the rotating cylinder can be transmitted to the edge of the substrate through the gas channel. Part of the purging gas containing the carbon element in the rotating cylinder is guided to the edge of the substrate, so that nitrogen doping at the edge of the substrate is inhibited, and the uniformity of the nitrogen doping concentration of the substrate is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor equipment, in particular to a silicon carbide epitaxial deposition device and a base component thereof. Background Art

[0002] Vapor deposition is a crucial process in the semiconductor industry, primarily used to deposit thin films on substrates. The process involves heating the substrate to a specific temperature within the reaction chamber of the vapor deposition equipment. A process gas is then introduced into the chamber, causing a chemical reaction on the substrate surface to form the desired thin film.

[0003] Typically, a silicon carbide epitaxial deposition system houses a rotating drum within the reaction chamber, which supports the substrate tray. During the process, the drum rotates the substrate, and process gases react chemically on the substrate surface, completing the film growth process.

[0004] During the silicon carbide (SiC) epitaxial growth process, differences in doping concentration occur between the edge and center of the epitaxial layer due to differential interactions between the edge and the growth environment. This edge effect results in poor doping uniformity across the SiC epitaxial wafer, impacting device performance and reliability. Utility Model Content

[0005] The purpose of the utility model is to provide a silicon carbide epitaxial deposition device and a base assembly thereof, which are used to solve the problem of poor uniformity of doping concentration of silicon carbide epitaxial wafers.

[0006] In order to achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] A base assembly for use in silicon carbide epitaxial deposition equipment comprises: a substrate tray having a sunken pit in its central region for accommodating a substrate; a rotating cylinder, the upper portion of which supports the substrate tray, the rotating cylinder being connected to a purge gas supply unit; a heater made of graphite, which is arranged inside the rotating cylinder; and a gas channel surrounding the substrate in the edge region of the substrate tray, through which the gas in the rotating cylinder can be transmitted to the edge of the substrate.

[0008] Optionally, the gas channel includes a plurality of air inlet holes, an annular air uniforming cavity and a plurality of air outlet holes connected in sequence, the annular air uniforming cavity is coaxial with the substrate tray, the air inlet holes pass through from the lower surface of the substrate tray to the annular air uniforming cavity, and the air outlet holes pass through from the upper surface of the substrate tray to the annular air uniforming cavity.

[0009] Optionally, the axes of the air inlet and the air outlet do not coincide with each other.

[0010] Optionally, the air inlet is larger than the air outlet.

[0011] Optionally, the air inlet holes and the air outlet holes are evenly distributed along the circumference of the substrate tray.

[0012] Optionally, the substrate tray includes a heat distributing plate and an annular tray seat, the heat distributing plate supports the tray seat, the inner area of the tray seat is recessed downward to form an annular step, and the annular step is used to support the substrate; the air inlet is formed on the heat distributing plate; the air outlet is formed on the tray seat; the annular air distributing cavity is formed on the upper surface of the heat distributing plate, or the annular air distributing cavity is formed on the lower surface of the tray seat, or a part of the annular air distributing cavity is formed on the upper surface of the heat distributing plate and the other part is formed on the lower surface of the tray seat.

[0013] Optionally, the air outlet is provided at an outer area of the tray seat.

[0014] Optionally, the air outlet is an inclined hole and is inclined toward the substrate.

[0015] Optionally, the angle between the axis of the air outlet and the axis of the substrate tray is no greater than 10°.

[0016] Optionally, an annular groove is provided along the outer edge of the step surface of the annular step.

[0017] Optionally, the air outlet is located in the annular groove.

[0018] Optionally, the uniform heating plate is made of graphite, or the uniform heating plate includes a graphite substrate and a silicon carbide coating, or the uniform heating plate includes a graphite substrate and a tantalum carbide coating.

[0019] Optionally, the rotating drum is connected to a carbon source supply unit and a purge gas supply unit respectively, or the rotating drum is connected to a mixed gas supply unit of the carbon source and the purge gas.

[0020] Optionally, the base assembly further includes: a rotating shaft and a rotating base, the rotating base is fixedly connected to the bottom of the rotating cylinder, the rotating shaft is fixedly connected to the rotating base, and is used to drive the rotating cylinder to rotate, and the gas in the rotating cylinder is passed into the rotating cylinder through the rotating shaft.

[0021] Optionally, the interior of the rotating drum further includes: a heat insulation screen located below the heater, and / or a reflection plate located between the heater and the heat insulation screen.

[0022] Optionally, at least one of the heat insulation screen and the reflective plate is made of graphite.

[0023] A silicon carbide epitaxial deposition device comprises: a reaction chamber; a shower head arranged at the top of the reaction chamber; and a base assembly as described above, arranged at the bottom of the reaction chamber.

[0024] Compared with the prior art, the utility model has the following advantages:

[0025] The base assembly provided by the present invention is provided with a gas channel surrounding the substrate in the edge area of the substrate tray, which guides a portion of the carbon-containing purge gas inside the rotating cylinder to the edge of the substrate, suppressing nitrogen doping at the edge of the substrate, thereby improving the uniformity of the nitrogen doping concentration of the substrate. The gas channel includes an air inlet, an annular uniform air cavity and an air outlet. By providing the annular uniform air cavity, the doping suppression gas is uniformly diffused in the annular uniform air cavity and then flows out from the air outlet, thereby improving the uniformity of the doping suppression gas at the edge of the substrate. The axis of the air inlet and the air outlet do not coincide with each other, so that the flow direction of the doping suppression gas in the gas channel changes, promoting the uniform diffusion of the gas in the annular uniform air cavity. An annular groove is provided to accommodate sediments to prevent excessive sediments from causing the substrate to tilt during the process. The air outlet is provided in the annular groove to further increase the carbon element concentration in the edge area of the substrate and prevent the process gas from forming sediments outside the edge of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0027] Figure 1 is a schematic diagram of an existing silicon carbide epitaxial deposition device;

[0028] Figure 2 A schematic diagram of a base assembly provided in one embodiment of the present utility model;

[0029] Figure 3a 、 Figure 3b are respectively Figure 2 The structure diagrams in the two dotted boxes on the left and right;

[0030] Figure 4a 、 Figure 4b They are respectively a structural diagram and a partial diagram of the tray seat of the first embodiment;

[0031] Figure 4c This is a structural diagram of the uniform heating plate of the first embodiment;

[0032] Figure 5a 、 Figure 5bThe second embodiment Figure 2 The structure diagrams in the two dotted boxes on the left and right;

[0033] Figure 6a 、 Figure 6b They are respectively a structural diagram and a partial diagram of the tray seat of the second embodiment;

[0034] Figure 7a 、 Figure 7b The third embodiment Figure 2 The structure diagrams in the two dotted boxes on the left and right;

[0035] Figure 8a 、 Figure 8b They are respectively a structural diagram and a partial diagram of the tray seat according to the third embodiment. DETAILED DESCRIPTION

[0036] The scheme proposed in the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the implementation method of the present invention. In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structure, proportion, size, etc. illustrated in the drawings of this specification are only used to match the content disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0037] Figure 1 It is a schematic diagram of an existing silicon carbide epitaxial deposition device. The silicon carbide epitaxial deposition device includes a reaction chamber 100, and a base assembly 200 is arranged at the bottom of the reaction chamber 100. The base assembly 200 includes a rotating cylinder 210 and a substrate tray 220, the rotating cylinder 210 is used to support the substrate tray 220, and the upper surface of the substrate tray 220 is used to carry the substrate W. A shower head 300 is provided at the top of the reaction chamber 100, and the process gas flowing in from the shower head 300 flows to the substrate W, and grows on the upper surface of the substrate W to produce the required epitaxial material layer. An exhaust device (not shown) is provided at the bottom of the reaction chamber 100 to discharge the reacted gas out of the reaction chamber 100. The flow direction of the process gas in the reaction chamber 100 is as follows: Figure 1 Indicated by the dotted arrow.

[0038] The base assembly 200 also includes a rotating shaft 230 and a rotating base 240. The rotating base 240 is fixedly connected to the bottom of the rotating cylinder 210. The rotating shaft 230 is fixedly connected to the rotating base 240 and is used to drive the rotating cylinder 210 to rotate. The base assembly 200 also includes a side straight cylinder 250. The side straight cylinder 250 is sleeved on the outside of the rotating cylinder 210 and has a gap with the outer side surface of the rotating cylinder 210. A plurality of pressure relief holes 211 are provided on the annular side wall of the rotating cylinder 210 to maintain the air pressure balance between the inside and outside of the rotating cylinder 210, and to prevent the phenomenon of flying discs etc. caused by the excessive air pressure inside the rotating cylinder 210. During the process, a purge gas is introduced into the inside of the rotating cylinder 210, and the flow direction of the purge gas is as follows. Figure 1 As shown by the dotted arrows in FIG. A portion of the purge gas flows through the outlet on the rotating base 240 and the gap, then out the top of the side cylinder 250 to prevent process gas from depositing on the outer wall of the rotating cylinder 210. Because the internal pressure of the rotating cylinder 210 is slightly higher than the pressure at the top outlet of the side cylinder 250, another portion of the purge gas flows out through the pressure relief hole 211 due to the pressure difference, thereby balancing the pressure difference between the inside and outside of the rotating cylinder 210.

[0039] As described in the background art, due to the edge effect, the nitrogen doping concentration in the edge region of the silicon carbide epitaxial layer is often higher than that in the central region, resulting in poor uniformity of the doping concentration of the silicon carbide epitaxial wafer.

[0040] Based on this, an embodiment of the present invention provides a base assembly, such as Figure 2 As shown, it includes: a substrate tray 220 having a recessed pit in its central region for accommodating a substrate W; a rotating cylinder 210, the upper portion of which supports the substrate tray 220, and the rotating cylinder 210 is connected to a purge gas supply unit; a graphite heater 261 disposed within the rotating cylinder for heating the substrate tray 220 and the substrate W above, the heater 261 being capable of precipitating carbon; and a gas channel 221 surrounding the substrate W is disposed in the edge region of the substrate tray 220, through which the gas within the rotating cylinder 210 can be transferred to the edge of the substrate W. In this embodiment, the gas channel 221 surrounding the substrate W is disposed in the edge region of the substrate tray 220 to guide the carbon-containing purge gas (i.e., doping suppression gas) within the rotating cylinder 210 to the edge of the substrate W, thereby increasing the carbon concentration at the edge of the substrate, thereby suppressing nitrogen doping in the edge region and improving the uniformity of the doping concentration of the epitaxial wafer.

[0041] In one embodiment, the rotating drum 210 is connected to a carbon source supply unit and a purge gas supply unit, or the rotating drum 210 is connected to a mixed gas supply unit of a carbon source and a purge gas. The purge gas may be Ar, and the carbon source gas may be C2H4 or C3H8. The doping suppression gas is introduced into the interior of the rotating drum 210 through the rotating shaft 230. Figure 1 The two gas flows are directed outwards as shown in FIG, and the other one flows into the edge of the substrate W through the gas channel 221 on the substrate tray 220 (the gas flow direction is as shown in FIG). Figure 2 ).

[0042] In another implementation, the rotating cylinders are respectively connected to the purge gas supply unit, and a graphite structure is further provided in the rotating cylinder 210; the carbon element in the doping suppression gas is precipitated by the structure, and the purge gas in the doping suppression gas is passed into the rotating cylinder 210 through the rotating shaft 230. It is understandable that during the process, the graphite structure in the rotating cylinder 210 precipitates carbon elements at high temperatures, and after the purge gas is passed into the rotating cylinder 210, the purge gas is mixed with the precipitated carbon elements to form the doping suppression gas. Similarly, the doping suppression gas is Figure 1 The two gas flows are directed outwards as shown in FIG, and the other one flows into the edge of the substrate W through the gas channel 221 on the substrate tray 220 (the gas flow direction is as shown in FIG). Figure 2 ). The structural member may be: a heater 261, and / or a heat shield 263 located below the heater 261, and / or a reflective plate 262 located between the heater 261 and the heat shield 263. The heat shield 263 is used to prevent heat from the heater 261 from being transferred downward, thereby improving the heating efficiency of the substrate W. The reflective plate 262 is used to reflect the heat radiated downward by the heater 261 to the substrate tray 220, thereby further improving the heating efficiency of the substrate W.

[0043] In this embodiment, Figure 3a 、 Figure 3bAs shown, the gas channel 221 includes a plurality of sequentially connected gas inlets 2211, an annular gas uniforming cavity 2212, and a plurality of gas outlets 2213. The annular gas uniforming cavity 2212 is coaxial with the substrate tray 220. The gas inlets 2211 extend from the lower surface of the substrate tray 220 to the annular gas uniforming cavity 2212, and the gas outlets 2213 extend from the upper surface of the substrate tray 220 to the annular gas uniforming cavity 2212. The gas inlets 2211 and the gas outlets 2213 are evenly distributed along the circumference of the substrate tray 220. By providing the annular gas uniforming cavity 2212, the doping suppression gas is uniformly diffused within the annular gas uniforming cavity 2212 before flowing out of the gas outlets 2213, thereby improving the uniformity of the doping suppression gas at the edge of the substrate W.

[0044] Furthermore, the axes of the air inlet 2211 and the air outlet 2213 do not coincide. The axes of the air inlet 2211 and the air outlet 2213 may be staggered along the circumferential and / or radial directions of the base tray 220. Thus, when the doping suppression gas flows into the annular uniform gas cavity 2212, the gas will further diffuse due to the partial obstruction of the annular uniform gas cavity 2212, and then flow out evenly from the air outlet 2213. That is, as long as the gas flows from the air inlet 2211 into the annular uniform gas cavity 2212, the gas will undergo a change in flow direction. Such a change will promote the uniform diffusion of the gas in the annular uniform gas cavity 2212, thereby improving the uniformity of the doping suppression gas. Optionally, the air inlet is larger than the air outlet to ensure a stable supply of doping suppression gas to the edge of the substrate W.

[0045] In this embodiment, Figure 3a 、 3bAs shown in Figures 4a, 4b, and 4c, the substrate tray 220 includes a heat spreader 222 and an annular tray seat 223. The heat spreader 222 supports the tray seat 223. The inner area of the tray seat 223 is recessed downward to form an annular step 2231, which is used to support the substrate W. The air inlet 2211 is formed on the heat spreader 222. The air outlet 2213 is formed on the tray seat 223. The annular air distribution cavity 2212 is formed on the upper surface of the heat spreader 222. In other embodiments, the annular air distribution cavity 2212 can also be formed on the lower surface of the tray seat 223, or a portion of the annular air distribution cavity 2212 is formed on the upper surface of the heat spreader 222, and the other portion is formed on the lower surface of the tray seat 223. The heat spreader 222 is used to evenly transfer the heat from the heater 261 to the substrate W. Optionally, the heat spreader 222 is made of graphite, which has excellent thermal conductivity and can enhance the heating effect on the substrate. Alternatively, the heat spreader 222 includes a graphite substrate and a silicon carbide coating, or a graphite substrate and a tantalum carbide coating. Forming a coating on the graphite substrate of the heat spreader 222 prevents the precipitation of impurities from the graphite substrate at high temperatures.

[0046] Combine Figure 4a 、 Figure 4b As shown, the gas outlet 2213 is disposed outside the tray seat 223 and near the annular step 2231. Furthermore, the gas outlet 2213 may be an inclined hole, tilted toward the substrate W, with the angle between the axis of the gas outlet 2213 and the axis of the substrate tray 220 being no greater than 10°. This can better guide the doping suppression gas toward the edge of the substrate W.

[0047] In another embodiment, Figure 5a 、 5b As shown in Figures 6a and 6b, an annular groove 2232 is provided along the outer edge of the step surface of the annular step 2231 for accommodating sediments to prevent excessive sediments from forming on the annular step 2231 during the process, causing the substrate W to tilt.

[0048] In yet another embodiment, Figure 7a 、 7b As shown in , 8a, and 8b, the gas outlet 2213 is located in the annular groove 2232, which can directly guide the doping-inhibiting gas to the edge of the substrate W, thereby increasing the carbon concentration in the edge region of the substrate W. In addition, in this embodiment, the doping-inhibiting gas can also prevent the process gas from forming deposits on the step surface and in the annular groove 2232.

[0049] Based on the same inventive concept, the present invention also provides a silicon carbide epitaxial deposition device, comprising: a reaction chamber; a shower head, the shower head being arranged at the top of the reaction chamber; and the above-mentioned base assembly, the base assembly being arranged at the bottom of the reaction chamber.

[0050] In summary, the base assembly provided by the present invention is provided with a gas channel surrounding the substrate in the edge area of the substrate tray, which guides a portion of the carbon-containing purge gas inside the rotating cylinder to the edge of the substrate, suppressing nitrogen doping at the edge of the substrate, thereby improving the uniformity of the nitrogen doping concentration of the substrate. The gas channel includes an air inlet, an annular uniform air cavity and an air outlet. By providing the annular uniform air cavity, the doping suppression gas is uniformly diffused in the annular uniform air cavity and then flows out from the air outlet, thereby improving the uniformity of the doping suppression gas at the edge of the substrate. The axis of the air inlet and the air outlet do not coincide with each other, so that the flow direction of the doping suppression gas in the gas channel changes, promoting the uniform diffusion of the gas in the annular uniform air cavity. An annular groove is provided to accommodate sediments to prevent excessive sediments from causing the substrate to tilt during the process. The air outlet is provided in the annular groove to further increase the carbon element concentration in the edge area of the substrate and prevent the process gas from forming sediments outside the edge of the substrate.

[0051] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0052] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as limiting the present invention. After reading the above description, various modifications and alternatives to the present invention will be readily apparent to those skilled in the art. Therefore, the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A susceptor assembly for use in a silicon carbide epitaxial deposition apparatus, characterized in that: include: A substrate tray has a central area with a recessed pit for accommodating a substrate; a rotating cylinder, an upper portion of which supports the substrate tray, and the rotating cylinder is connected to a purge gas supply unit; a graphite heater, which is arranged inside the rotating cylinder; A gas channel surrounding the substrate is provided in the edge area of the substrate tray, and the gas in the rotating cylinder can be transmitted to the edge of the substrate through the gas channel.

2. The base assembly according to claim 1, wherein: The gas channel includes a plurality of air inlet holes, an annular air uniforming cavity and a plurality of air outlet holes connected in sequence. The annular air uniforming cavity is coaxial with the substrate tray. The air inlet holes pass through from the lower surface of the substrate tray to the annular air uniforming cavity, and the air outlet holes pass through from the upper surface of the substrate tray to the annular air uniforming cavity.

3. The base assembly according to claim 2, wherein: The axes of the air inlet and the air outlet do not coincide with each other.

4. The base assembly according to claim 2, wherein: The air inlet is larger than the air outlet.

5. The base assembly according to claim 2, wherein: The air inlet holes and the air outlet holes are evenly distributed along the circumference of the substrate tray.

6. The base assembly according to claim 2, wherein: The substrate tray includes a heat spreader and an annular tray seat, the heat spreader supports the tray seat, and the inner area of the tray seat is recessed downward to form an annular step, and the annular step is used to support the substrate; The air inlet hole is formed on the heat-distributing plate; The air outlet is formed on the tray seat; The annular air-homogenizing cavity is formed on the upper surface of the heat-homogenizing plate, or the annular air-homogenizing cavity is formed on the lower surface of the tray seat, or a part of the annular air-homogenizing cavity is formed on the upper surface of the heat-homogenizing plate and the other part is formed on the lower surface of the tray seat.

7. The base assembly according to claim 6, wherein: The air outlet is arranged at an outer area of the tray seat.

8. The base assembly according to claim 7, wherein: The air outlet is an oblique hole and is inclined toward the substrate.

9. The base assembly according to claim 8, wherein: The angle between the axis of the air outlet and the axis of the substrate tray is no greater than 10°.

10. The base assembly according to claim 6, wherein: An annular groove is provided along the outer edge of the step surface of the annular step.

11. The base assembly according to claim 10, wherein: The air outlet is located in the annular groove.

12. The base assembly according to claim 6, wherein: The material of the uniform heating plate is graphite, or the uniform heating plate includes a graphite base and a silicon carbide coating, or the uniform heating plate includes a graphite base and a tantalum carbide coating.

13. The base assembly of claim 1, wherein: The rotating drum is connected to a carbon source supply unit and a purge gas supply unit respectively, or the rotating drum is connected to a mixed gas supply unit of the carbon source and the purge gas.

14. The base assembly according to claim 1 or 13, wherein: The base assembly further includes: a rotating shaft and a rotating base, wherein the rotating base is fixedly connected to the bottom of the rotating cylinder, and the rotating shaft is fixedly connected to the rotating base for driving the rotating cylinder to rotate, and the gas in the rotating cylinder is passed into the rotating cylinder through the rotating shaft.

15. The base assembly of claim 14, wherein: The interior of the rotating drum further includes: a heat insulation screen located below the heater, and / or a reflection plate located between the heater and the heat insulation screen.

16. The base assembly of claim 15, wherein: At least one of the heat insulation screen and the reflective plate is made of graphite.

17. A silicon carbide epitaxial deposition device, characterized in that: include: reaction chamber; A shower head is arranged at the top of the reaction chamber; The susceptor assembly according to any one of claims 1 to 16, disposed at the bottom of the reaction chamber.

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