Tray and semiconductor device

Abstract

The invention discloses a tray and semiconductor equipment, and belongs to the technical field of semiconductor processing, the tray comprises a bearing part and a limiting part arranged around the bearing part, and the bearing part is provided with a concave surface and a bearing surface arranged around the concave surface; the bearing surface is a plane, and the bearing surface is used for bearing a wafer; the concave surface is concavely arranged relative to the bearing surface; the limiting part protrudes towards one side far away from the concave surface relative to the bearing surface; the tray is further provided with a flow guide hole penetrating through the bearing part, and the flow guide hole extends to the concave face. The tray can solve the problems that when an existing tray is used for bearing a wafer to carry out an epitaxial process, silicon slag is seriously formed in the area, close to the outer edge, of the lower surface of the wafer, and the yield of the wafer is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor processing, and particularly relates to a tray and a semiconductor device. BACKGROUND

[0002] An epitaxial process is a process of growing a single-crystal thin film on a wafer. In a silicon epitaxial process, the wafer is carried on a tray, and a process gas is controlled to flow above the wafer, so that the process gas chemically reacts on the surface of the wafer to generate silicon elements, and then a silicon element thin film is formed on the surface of the wafer.

[0003] In order to ensure that the spacing between the process gas and the wafer is substantially equal at any position on the wafer surface when the process gas flows through, so as to ensure that the thickness uniformity of the silicon element thin film formed on the wafer is relatively good, in the current tray, it is usually necessary to finely process the carrying surface of the tray to reduce the roughness of the carrying surface as much as possible. At the same time, the carrying surface is in the shape of a conical or circular side surface, so that after the wafer is carried on the carrying surface, the wafer is in a linear contact matching relationship with the carrying surface only through the outer edge of the lower surface. In this case, after the wafer is placed on the carrying surface, if there is an included angle between the upper surface of the wafer and the horizontal plane, the wafer will slide on the carrying surface with relatively small roughness under the action of its own gravity, and then the upper surface of the wafer and the horizontal plane are parallel to each other or substantially parallel to each other, so as to ensure that the wafer has the ability of automatic centering.

[0004] However, in the epitaxial process using the above-mentioned tray, the process gas will escape to the back surface of the wafer through the gap between the wafer and the tray, and since the outer edge of the lower surface of the wafer is in contact with the tray, the process gas is easily adhered to the area near the outer edge of the lower surface of the wafer, forming silicon slag. With the increase of the process time, the growth rate of the silicon slag in the area near the outer edge of the lower surface of the wafer is continuously improved compared with other areas of the lower surface of the wafer, so that at the end of the process, the silicon slag in the area near the outer edge of the lower surface of the wafer will cause the wafer to be adhered to the tray, and then the wafer is easily damaged during the unloading process. SUMMARY

[0005] The purpose of the embodiments of the present application is to provide a tray and a semiconductor device to solve the problem that the silicon slag formed in the area near the outer edge of the lower surface of the wafer is relatively serious when the wafer is carried on the current tray to perform the epitaxial process, and the yield of the wafer is relatively low.

[0006] In a first aspect, the present application discloses a tray, which comprises a carrying part and a limiting part arranged around the carrying part, the carrying part has a concave surface and a carrying surface arranged around the concave surface; The carrying surface is a plane, and the carrying surface is used for carrying a wafer. The concave surface is recessed relative to the bearing surface; The limiting portion is protruded relative to the bearing surface to the side away from the concave surface; The tray is further provided with a flow guide hole penetrating through the bearing portion, and the flow guide hole extends to the concave surface.

[0007] In a second aspect, the application discloses a semiconductor device, which comprises a base ring, a first cover, a second cover and the above-mentioned tray. The first cover and the second cover are respectively arranged above and below the base ring to form a process chamber with the base ring. The tray is arranged in the process chamber. The base ring is provided with an air inlet hole and an air outlet hole, which are respectively located at opposite ends of the process chamber and communicate with the process chamber.

[0008] The tray comprises a bearing portion and a limiting portion arranged around the bearing portion, the bearing portion has a concave surface and a bearing surface arranged around the concave surface, wherein the bearing surface is a plane, and in the process, the wafer can be carried on the bearing surface of the plane structure to increase the contact (or relative) area between the wafer and the bearing surface. In this case, even if the gas enters between the lower surface of the wafer and the bearing surface through the outer edge of the wafer, the amount of process gas adhered to any position in the lower surface of the wafer can be greatly reduced due to the relatively large area of the wafer in contact with the bearing surface. In addition, a film layer with extremely small thickness can be formed in the area of the wafer in contact with the bearing surface. The film layer has a small thickness, a large distribution range and a relatively high uniformity of the entire film layer, which basically does not adversely affect the quality of the back surface of the wafer.

[0009] In the tray, the limiting portion is protruded relative to the bearing surface to the side away from the concave surface, so that the limiting portion can provide a certain limiting effect for the wafer carried on the bearing surface. At the same time, the bearing surface is arranged outside the concave surface, and the concave surface is recessed relative to the bearing surface. In addition, the tray is further provided with a flow guide hole penetrating through the bearing portion, and the flow guide hole extends to the concave surface. In this case, even if the wafer needs to be heated in the process, the cavity formed between the wafer and the bearing portion can communicate with the space outside the bearing portion through the flow guide hole, so that the gas in the above-mentioned cavity can quickly escape to the outside of the bearing portion through the flow guide hole after the gas between the lower surface of the wafer and the bearing surface (and the concave surface) is heated and expanded. This can prevent the wafer from lifting relative to the bearing portion due to the expansion of the gas between the wafer and the bearing portion, and can prevent the wafer from drifting relative to the bearing portion due to the driving effect of the gas flow during the escape of the gas between the wafer and the bearing portion, thereby adversely affecting the process effect of the wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is a schematic structural diagram of a tray disclosed in an embodiment of the present application; Figure 2 Schematic diagram of the distribution of crystal orientation in a wafer; Figure 3 is the height distribution curve of multiple points on the bearing surface obtained by three-coordinate measurement; Figure 4 A schematic diagram of a specific structure of a tray disclosed in an embodiment of the present application; Figure 5 This is another specific structural schematic diagram of the tray disclosed in the embodiment of this application; Figure 6 This is another specific structural schematic diagram of the tray disclosed in the embodiment of the present application; Figure 7 Schematic diagram for comparison of flatness curves of epitaxial films; Figure 8 This is a schematic structural diagram of the semiconductor device disclosed in an embodiment of the present application.

[0011] Reference numerals: 100-tray, 110-bearing part, 111-concave surface, 112-bearing surface, 113-guide hole, 120-limiting part, 121-raised area, 122-recessed area, 130-guide part, 200-base ring, 210-air inlet, 220-exhaust hole, 310-first cover, 320-second cover, 410-first liner, 420-second liner, 500-Preheating ring, 900-wafer, 910-first crystal direction, 920-second crystal direction. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0013] The terms "first", "second", and the like in the description and in the claims of the present application are used for distinguishing between similar objects and not necessarily for describing a specific sequential or chronological order. It is to be understood that the use of these terms herein is merely for distinguishing between the objects and does not necessarily indicate a specific order or chronology of events as is meant in a legal sense. The data used is not mutually exclusive, and the embodiments of the present application can be practiced in other than the order detailed herein without departing from the spirit or scope of the application as will be understood by those of ordinary skill in the art. Also, the use of "and / or" means that the items so conjoined can each be present or absent, that one or more items can be present or absent, and that one or more of those items that are present can be present or absent. It is not intended that the "and / or" be interpreted as limiting every combination of items between the "and" and "or" set positions unless explicitly stated so. It is intended that the "and / or" be interpreted to mean that every combination is possible.

[0014] As shown in Figures 1-8 Embodiments of the present application disclose a tray 100 and a semiconductor device, the tray 100 can be used to carry a wafer 900, so that the wafer 900 can be processed. For example, in an epitaxial process, the wafer 900 can be carried on the tray 100, and a process gas can flow through the upper surface of the wafer 900, so as to form a single crystal thin film on the upper surface of the wafer 900.

[0015] As shown in Figure 1 Embodiments of the present application disclose a tray 100 including a carrying part 110 and a limiting part 120, wherein the limiting part 120 is arranged around the carrying part 110. In more detail, in the tray disclosed by embodiments of the present application, the carrying part 110 has a concave surface 111 and a carrying surface 112, the carrying surface 112 is a structure directly used to carry the wafer 900 in the tray 100, and the carrying surface 112 is arranged around the concave surface 111, in other words, the carrying surface 112 is a closed annular surface structure, and the concave surface 111 is located in the area surrounded by the carrying surface 112.

[0016] At the same time, the limiting part 120 is arranged protruding to the side away from the concave surface 111 relative to the carrying surface 112, that is, in the embodiments of the present application, the limiting part 120 is integrally arranged protruding above the carrying surface 112, which enables the limiting part 120 to provide a limiting effect for the wafer 900 carried on the carrying surface 112. Of course, in the processing of the tray 100, the limiting part 120 and the carrying part 110 can be formed in an integral molding manner, so as to improve the connection reliability therebetween.

[0017] As described above, in the related art, the tray 100 provides a bearing function for the wafer 900 by setting a bearing surface in the shape of a conical or circular conical side surface, so that after the wafer 900 is placed on the bearing surface, the wafer 900 can be automatically aligned, so that the upper surface of the wafer 900 is in a state of mutual parallelism or substantially mutual parallelism with the horizontal plane, and then the spacing between the process gas and the upper surface of the wafer 900 is substantially equal when the process gas flows through the upper surface of the wafer 900, so as to improve the uniformity of the thickness of the epitaxial layer formed at different positions in the wafer 900. However, when the wafer 900 is carried by the tray 100 and the epitaxial process is performed, the silicon slag adhered and formed in the area close to the outer edge of the lower surface of the wafer 900 is more serious, which will have a greater adverse effect on the yield of the wafer.

[0018] Therefore, in the embodiment of the present application, as shown in Figure 1 the bearing surface 112 of the tray 100 is a plane, and the plane structure of the bearing surface 112 is used to carry the wafer 900, so that after the wafer 900 is carried on the bearing surface 112, the wafer 900 and the bearing surface 112 can be in a surface contact relationship, so as to increase the contact area between the wafer 900 and the bearing surface 112. In the case of using the technical solution disclosed in the embodiment of the present application, when the process gas enters the gap between the wafer 900 and the bearing surface 112, the gas can flow to different positions in the contact area between the wafer 900 and the bearing surface 112 in a relatively dispersed manner, and a film with extremely small thickness is formed on the area of the lower surface of the wafer 900 in contact with the bearing surface 112, so that the contact area between the wafer 900 and the bearing surface 112 is not too small, which can prevent the gas from accumulating in the area close to the outer edge of the lower surface of the bearing surface 112, causing the amount of silicon slag formed in the aforementioned area to be too large, and thus preventing the wafer from being easily damaged due to adhesion between the wafer and the tray during the unloading process.

[0019] As described above, in the case of using the technical solution disclosed in the embodiment of the present application, since the area of the wafer 900 where the film layer is formed is relatively large, the thickness of the film layer is extremely small, and the amount of gas contained in any position of the area of the wafer 900 in contact with the bearing surface 112 is also relatively small due to the close contact relationship between the bearing surface 112 and the wafer 900, which can ensure that the thickness of the formed film layer is extremely small, and the distribution range of the film layer is relatively large, so that even if the back surface of the wafer 900 is formed with a film layer, the wafer 900 will not be adhered to the tray, so as to not affect the yield of the wafer.

[0020] In addition, in the embodiment of the present application, since the bearing surface 112 is a plane, when the wafer 900 is supported on the bearing surface 112, the wafer 900 can be relatively stable, and when the tray 100 is installed, by adjusting and controlling the levelness of the bearing surface 112 of the tray 100, the parallelism between the upper surface of the wafer 900 and the horizontal plane after the wafer 900 is supported on the bearing surface 112 can be relatively high, thereby ensuring that the process uniformity at different positions on the wafer 900 is relatively high.

[0021] Meanwhile, in the embodiment of the present application, as shown in Figure 1 the recessed surface 111 is recessed relative to the bearing surface 112, in other words, the recessed surface 111 is located below the bearing surface 112 as a whole, and in the case where the bearing surface 112 bears the wafer 900, the area of the wafer 900 facing the recessed surface 111 can be spaced apart from the recessed surface 111, in which case, a cavity can be formed between the wafer 900 and the recessed surface 111, which can cooperate with the flow guide hole 113 mentioned below to ensure that the gas in the aforementioned cavity can exchange with the gas outside the cavity, preventing the wafer from drifting relative to the bearing portion 110 due to the focusing of a large amount of process gas under the wafer during normal pressure process.

[0022] In detail, the tray 100 is also provided with a flow guide hole 113, the flow guide hole 113 is arranged through the bearing portion 110, and the flow guide hole 113 extends to the recessed surface 111, so that the aforementioned cavity formed between the wafer 900 and the recessed surface 111 can be in communication with the outside of the cavity through the flow guide hole 113, in which case, the gas in the aforementioned cavity can exchange and flow with the gas outside the cavity.

[0023] More specifically, the flow guide hole 113 can extend along the radial direction of the wafer 900 to extend from the outer circumferential surface of the bearing portion 110 to one side of the aforementioned cavity, in order to reduce the processing difficulty of the flow guide hole 113 and as much as possible to improve the exchange efficiency of the gas inside and outside the cavity, in one specific embodiment of the present application, the flow guide hole 113 extends along the bearing direction of the bearing surface 112, and the flow guide hole 113 can be arranged at the bottom of the aforementioned cavity, the bearing direction of the bearing surface 112 is usually vertical, for this purpose, the flow guide hole 113 can extend upward from the lower surface of the bearing portion 110 to the recessed surface 111, so that the flow guide hole 113 penetrates through the bearing portion 110, which can also reduce the processing difficulty of the flow guide hole 113.

[0024] To further improve the efficiency of the exchange between the gas in the cavity formed between the wafer 900 and the concave surface 111 and the gas outside the bearing part 110, the number of the flow guide holes 113 is optional, and the distribution of the plurality of flow guide holes 113 and the parameters such as the aperture of each flow guide hole 113 can be selected flexibly according to actual needs, which is not limited herein.

[0025] In the epitaxial process, in order to improve the epitaxial efficiency, the wafer 900 needs to be heated, and in the heating process, the gas in the space formed between the wafer 900 and the tray 100 will expand, and even if any position of the lower surface of the wafer 900 is supported on the bearing surface 112 (that is, the bearing part 110 no longer has the concave surface 111, and the upper surface of the bearing surface 112 is a flat structure), due to the roughness of the wafer 900 and the bearing surface 112, a certain amount of gas will be left between the lower surface of the wafer 900 and the bearing surface 112, and the aforementioned gas will expand after being heated, which may cause the wafer 900 to lift, and as the wafer 900 lifts, part of the gas between the lower surface of the wafer 900 and the bearing surface 112 escapes, which may drive the wafer 900 to drift relative to the bearing part 110 under the action of the gas flow, which will affect the process effect of the wafer 900, and may also scratch the back of the wafer 900, resulting in a decrease in the yield of the wafer 900.

[0026] Therefore, as described above, the tray 100 disclosed in the embodiments of the present application can appropriately reduce the contact area between the wafer 900 and the entire bearing part 110 by setting the concave surface 111 and the flow guide hole 113, so that the amount of gas left between the wafer 900 and the bearing surface 112 can also be appropriately reduced, so that even if the gas between the wafer 900 and the bearing surface 112 expands due to heating, the driving effect generated is relatively small. At the same time, under the action of the flow guide hole 113, once the gas between the wafer 900 and the bearing part 110 expands due to heating, the gas can quickly escape to the outside of the bearing part 110 through the flow guide hole 113, which can further prevent the wafer 900 from drifting uncontrollably relative to the bearing part 110 during the heating process, and adversely affecting the process effect of the wafer 900.

[0027] The embodiment of the present application discloses a tray 100, which comprises a bearing part 110 and a limiting part 120 arranged around the bearing part 110, the bearing part 110 has a concave surface 111 and a bearing surface 112 arranged around the concave surface 111, wherein the bearing surface 112 is a plane, and then in the process, the wafer 900 can be carried on the bearing surface 112 with a plane structure, so as to increase the contact (or relative) area between the wafer 900 and the bearing surface 112, in this case, even if the gas enters between the lower surface of the wafer 900 and the bearing surface 112 through the outer edge of the wafer 900, due to the relatively large area of the wafer 900 relative to (or in contact with) the bearing surface 112, the amount of process gas adhered to any position in the lower surface of the wafer 900 can be greatly reduced, and the area of the wafer 900 in contact with the bearing surface 112 can form a film layer with extremely small thickness, the thickness of the aforementioned film layer is small, the distribution range of the film layer is large, and the uniformity of the entire film layer is relatively high, so as to basically not adversely affect the back surface quality of the wafer 900, and ensure that the wafer 900 can pass the mirror inspection normally.

[0028] In the tray 100, the limiting part 120 is arranged to protrude away from the concave surface 111 relative to the bearing surface 112, so that the limiting part 120 can provide a certain limiting effect for the wafer 900 carried on the bearing surface 112, at the same time, the bearing surface 112 is arranged outside the concave surface 111, and the concave surface 111 is arranged to be recessed relative to the bearing surface 112, in addition, the tray 100 is also provided with a flow guide hole 113, the flow guide hole 113 is arranged to penetrate through the bearing part 110, and the flow guide hole 113 extends to the concave surface 111. In this case, even if the wafer 900 needs to be heated in the process, since the cavity formed between the wafer 900 and the bearing part 110 can be communicated with the space outside the bearing part 110 through the flow guide hole 113, so that after the gas between the lower surface of the wafer 900 and the bearing surface 112 (and the concave surface 111) is heated and expanded, the gas in the aforementioned cavity can quickly escape to the outside of the bearing part 110 through the flow guide hole 113, which can prevent the wafer 900 from lifting relative to the bearing part 110 due to the expansion of the gas between the wafer 900 and the bearing part 110, and can prevent the wafer 900 from drifting relative to the bearing part 110 due to the driving effect of the gas flow during the process of the gas escaping between the wafer 900 and the bearing part 110, so as to adversely affect the process effect of the wafer 900.

[0029] As described above, in the tray 100 disclosed in the embodiments of the present application, the bearing surface 112 is a plane. It should be noted that, due to the current machining precision and other external conditions, the bearing surface 112 of the actually machined tray 100 may not be a plane in an ideal state, but this does not affect the protection scope of the technical solutions disclosed in the present application. Generally, in the actual machining process, if the flatness of the bearing surface 112 formed on the tray 100 is less than 1 mm, the bearing surface 112 of the tray 100 can be considered as a plane.

[0030] Obviously, in the case where the flatness of the bearing surface 112 is relatively large, when viewed in an enlarged manner, the wafer 900 is objectively supported on some points on the bearing surface 112 with relatively high heights. In order to further reduce the volume of the space between the wafer 900 and the bearing surface 112, and thus reduce the amount of gas adhered to the lower surface of the wafer 900, in one specific embodiment of the application, the flatness of the bearing surface 112 can be less than or equal to 0.1 mm.

[0031] Moreover, in the case where the above technical solution is adopted, the parallelism between the wafer 900 and the horizontal plane when the wafer 900 is placed on the bearing surface 112 can be further improved, so as to prevent the wafer 900 from being caused to have different distances between different positions on the wafer 900 and the process gas due to a relatively large included angle between the wafer 900 and the horizontal plane, and thus causing the thickness of the film layer formed at different positions on the wafer 900 to have a large difference.

[0032] As described above, due to the current machining conditions, the wafer 900 is actually directly supported on several points on the bearing surface 112 with relatively large heights. In order to further prevent the area of the wafer 900 corresponding to a support point on the bearing surface 112 from easily accumulating more process gas due to the height of the support point being too high relative to other support points, and thus causing the silicon residue in the area to be more, in the embodiments of the present application, the height difference between at least three points on the bearing surface 112 for supporting the wafer 900 can be less than 0.05 mm.

[0033] In detail, from a microscopic perspective, the bearing surface 112 has at least three points for supporting the wafer 900, so as to ensure that the wafer 900 can form a relatively static state with the bearing surface 112. In the embodiments of the present application, the aforementioned three points are the three points on the bearing surface 112 with the largest height values. Since the height values of the aforementioned three points may differ, in the embodiments of the present application, the spacing range of the aforementioned three points in the bearing direction of the bearing surface 112 is limited. Specifically, in the bearing direction of the bearing surface 112, the spacing between the at least three points for supporting the wafer 900 is less than or equal to 0.05 mm.

[0034] To further improve the stability of the wafer 900 on the bearing surface 112, and further improve the uniformity of the film layer formed on the back surface of the wafer 900, in the embodiment of the present application, the bearing surface 112 can include at least three annular bearing areas, and the bearing areas are distributed along the circumferential direction of the bearing surface 112. At the same time, in the bearing direction of the bearing surface 112, the spacing between the highest points of each bearing area is less than or equal to 0.05mm.

[0035] Further, the number of bearing areas can be greater than or equal to 4, to further improve the overall support stability of the wafer 900 on the bearing surface 112, and also to improve the parallelism between the wafer 900 supported on the bearing surface 112 and the horizontal plane.

[0036] It should be noted that during the processing of the bearing surface 112, the bearing surface 112 can be processed according to the above requirements to form a bearing surface 112 that meets the above requirements. After the bearing surface 112 is processed, the flatness and other parameters of the bearing surface 112 can be detected using corresponding instruments to ensure that the formed bearing surface 112 meets the above requirements.

[0037] In one specific embodiment of the present application, a three-coordinate measuring instrument can be used to detect the flatness of the formed bearing surface 112 and the height difference between the highest points in each bearing area. During detection, points can be taken along the circumferential direction of the bearing surface 112, for example, one point can be taken every 1°, and a rectangular coordinate system is established, taking the Z-direction height of each of the 360 points as the vertical coordinate, and taking the angle of the point as the horizontal coordinate, to form a fitting curve, as shown in Figure 3 In this curve, the curve formed by the obtained points has four peaks, in which case the bearing surface 112 can be divided into four bearing areas, each bearing area covering about 90°, and each bearing area has a highest point, that is, Figure 3 The four maximum values M in the four highest points correspondingly, in the present application, the height difference between the four highest points is less than or equal to 0.05mm.

[0038] Further, the angles between the aforementioned four highest points can also be made to be relatively equal, which makes the stability of the wafer 900 when supported on the bearing surface 112 relatively better, and can further improve the thickness of the film layer formed on the part of the lower surface of the wafer 900 corresponding to different areas of the bearing surface 112, to further prevent the case that the amount of silicon residue at a certain position on the lower surface of the wafer 900 is relatively large.

[0039] As mentioned above, during the process of the wafer 900, the wafer 900 can also need to be heated, and during the heating process, the gas in the space between the wafer 900 and the bearing part 110 can expand. In order to further prevent the gas in the aforementioned space from causing the wafer 900 to drift relative to the bearing part 110 during the expansion process, in a further embodiment of the present application, the roughness of the bearing surface 112 can be greater than 0.5 um. In this case, the wafer 900 and the bearing surface 112 have a certain friction, so as to resist the tendency of the wafer 900 to drift due to the expansion of the gas, so as to further improve the stability of the relative fixing relationship between the wafer 900 and the bearing surface 112.

[0040] Of course, in order to prevent the bearing surface 112 from being too rough and adversely affecting the uniformity of the film layer on the lower surface of the wafer 900, in a specific embodiment of the present application, the roughness of the bearing surface 112 can be less than 2 um. That is, in the tray disclosed in the embodiments of the present application, the roughness of the bearing surface 112 is between 0.5 um and 2 um, for example, the roughness of the bearing surface 112 can be 0.5 um, 0.8 um, 1.0 um, 1.5 um or 2 um, etc.

[0041] As mentioned above, the bearing part 110 has a concave surface 111, and the concave surface 111 is recessed relative to the bearing surface 112. Optionally, the cavity formed by the concave surface 111 and the wafer 900 can be a cubic structure, in which case the concave surface 111 is a cubic outer surface structure. In order to reduce the processing difficulty of the concave surface 111 and as far as possible to reduce the volume of the cavity formed between the wafer 900 and the concave surface 111, in another embodiment of the present application, the concave surface 111 is an arc-shaped curved surface as a whole. Of course, due to the machining precision, the concave surface 111 is not an ideal curved surface, and there can be a certain up-and-down jump in the extension process of the surface type. That is, in the radial direction of the bearing surface 112, any two points in the concave surface 111, including a first point and a second point, the distance between the first point and the lowest point of the concave surface 111 is smaller, but in the bearing direction of the bearing surface 112, the distance between the first point and the bearing surface 112 is not necessarily greater than the distance between the second point and the bearing surface 112. Of course, during the formation of the concave surface 111, the amount of up-and-down jump of the surface type cannot be too large, and as a whole, the greater the radial dimension between the point in the concave surface 111 and the lowest point, the smaller the height difference between the point and the bearing surface 112.

[0042] To this end, in the embodiments of the present application, the concave surface 111 can include a central region and a plurality of annular regions, wherein the plurality of annular regions are sequentially arranged outside the central region. Meanwhile, in the bearing direction of the bearing surface 112, the average value of the spacing between each point of the central region and the bearing surface 112 is greater than the average value of the spacing between each point of any annular region and the bearing surface 112, that is, when the bearing surface 112 is regarded as the top surface of the bearing part 110, the central region as a whole is located below any annular region; and in the bearing direction of the bearing surface 112, among any two adjacent annular regions, the average value of the spacing between each point of the one closer to the central region and the bearing surface 112 is less than the average value of the spacing between each point of the one farther from the central region and the bearing surface 112, that is, any annular region closer to the central region is located below the annular region farther from the central region.

[0043] In the embodiments of the present application, the central region is the one with the largest height difference between the concave surface 111 and the bearing surface 112 as a whole, and the central region is located at the central position of the concave surface 111 as a whole, but this does not mean that the central region must be at the most central position of the concave surface 111. Correspondingly, among the plurality of annular regions, the closer to the central region, the greater the height difference between the one and the bearing surface 112, and accordingly, for two points in the same annular region, the one with the smaller radial distance from the central region is not necessarily the one with the greater height difference from the bearing surface 112.

[0044] In one specific embodiment of the present application, intuitively, the concave surface 111 is a continuous curved surface. And in the process of forming the tray 100, the center of the bearing surface 112, the center of the concave surface 111 and the center of the limiting part 120 can be made to coincide with each other as much as possible, and when the wafer 900 is transmitted, the center of the wafer 900 supported on the bearing surface 112 also coincides with the center of the bearing surface 112, which can improve the process uniformity of the wafer 900.

[0045] In order to further reduce the volume of the space between the wafer 900 and the concave surface 111, thereby reducing the amount of process gas that can be contained in the cavity, so as to reduce the amount of process gas adhering to the lower surface of the wafer 900 from the source, thereby reducing the thickness of the formed film layer, in one specific embodiment of the present application, in the direction perpendicular to the bearing surface 112, the lowest point of the central region, that is, the spacing between the center of the concave surface 111 and the bearing surface 112, can be less than or equal to 0.3 mm.

[0046] In the tray 100 disclosed in the embodiment of the present application, the position-limiting portion 120 can include a plurality of raised areas 121 and a plurality of recessed areas 122, wherein the plurality of raised areas 121 and the plurality of recessed areas 122 are alternately distributed along the circumference of the position-limiting portion 120, and in a direction perpendicular to the bearing surface 112, the upper surface of each recessed area 122 is lower than the upper surface of each raised area 121. Of course, since the position-limiting portion 120 is generally located on the side of the bearing surface 112 away from the recessed surface 111, the upper surface of each recessed area 122 and the upper surface of each raised area 121 are both located on the side of the bearing surface 112 away from the recessed surface 111.

[0047] When adopting the above technical solution, if there are differences in the process rates of different areas in the wafer 900, the relative position between the wafer 900 and the tray 100 (the raised area 121 and multiple recessed areas 122) can be designed so that the area with a relatively high process rate in the wafer 900 corresponds to the raised area 121, and the area with a relatively low process rate in the wafer 900 corresponds to the recessed area 122. In this case, since the upper surface of the raised area 121 is higher than the upper surface of the recessed area 122, the flow and replacement rates of the process gas in the recessed area 122 are relatively fast, thereby compensating for the difference in process rates between the corresponding areas in the wafer 900 and improving the uniformity of the entire surface of the wafer 900.

[0048] In a specific embodiment of the present application, the crystal orientation is a factor that affects the uniformity of the epitaxial process on the wafer 900. Specifically, in the epitaxial process of the wafer 900, the crystal orientation of the wafer 900 affects the growth rate of the film layer. Figure 2 As shown, the wafer 900 carried on the carrying surface 112 has a first crystal direction 910 and a second crystal direction 920, wherein the first crystal direction 910 can be <110> The second crystal direction 920 can be <100> In terms of crystal direction, affected by parameters such as electron mobility, under the same epitaxial conditions, the growth rate of the area where the first crystal direction 910 is located is greater than the growth rate of the area where the second crystal direction 920 is located. This results in differences in the film thickness in the areas on the upper surface of the wafer 900 corresponding to the first crystal direction 910 and the second crystal direction 920, respectively, which affects the uniformity of the epitaxial process.

[0049] To this end, in the tray 100 disclosed in the embodiment of the present application, in the radial direction of the wafer 900, a raised area 121 can be provided at the outer side of the first crystal direction 910, and a recessed area 122 can be provided at the outer side of the second crystal direction 920. As shown above, the upper surface of the recessed area 122 is lower than the upper surface of the raised area 121.

[0050] In the technical solution, the upper surface of the convex region 121 corresponding to the first crystal direction 910 in the limiting portion 120 is relatively high, so the blocking degree of the process gas flowing from the outer edge side of the limiting portion 120 in the tray 100 is relatively high. Correspondingly, the upper surface of the concave region 122 corresponding to the second crystal direction 920 in the limiting portion 120 is relatively low, so the blocking degree of the process gas by the concave region 122 is relatively low. Therefore, relatively more process gas can flow to the concave region 122 with a relatively slow growth rate due to the crystal direction, so as to balance the growth speed of the regions corresponding to the first crystal direction 910 and the second crystal direction 920 on the wafer 900, and improve the thickness uniformity of the epitaxial film layer.

[0051] In an embodiment of the present application, the upper surface of each of the convex region 121 and the concave region 122 can be higher than the upper surface of the wafer 900. In order to further improve the amount of gas entering above the wafer 900 through the concave region 122 corresponding to the second crystal direction 920, in an embodiment of the present application, the upper surface of the convex region 121 can be higher than the upper surface of the wafer 900 carried on the bearing surface 112, and the upper surface of the concave region 122 can be lower than or flush with the upper surface of the wafer 900 carried on the bearing surface 112, so as to further improve the thickness uniformity of the parts corresponding to the first crystal direction 910 and the second crystal direction 920 in the epitaxial film layer on the wafer 900, respectively.

[0052] In more detail, in the process of forming the convex region 121 and the concave region 122, the convex region 121 can be a mirror-symmetrical structure, and more specifically, each convex region 121 can be a mirror-symmetrical structure. In an embodiment of the present application, the symmetry axis of the convex region 121 can extend in the radial direction of the tray 100. That is, in an embodiment of the present application, any convex region 121 can be divided into two parts by its own symmetry axis, and the two parts are symmetrical to each other with respect to a plane perpendicular to the bearing surface and passing through the symmetry axis. Of course, the angle of each convex region 121 extending to both sides from the symmetry axis can be determined flexibly according to actual needs. Similarly, in an embodiment of the present application, the concave region 122 is also mirror-symmetrical, that is, the concave region 122 is a mirror-symmetrical structure, and the symmetry axis of the concave region 122 extends in the radial direction of the tray. Furthermore, each concave region 122 can be a mirror-symmetrical structure, and the symmetry axis of each concave region 122 can extend in the radial direction of the tray.

[0053] Of course, in order to ensure the comprehensive limiting of the limiting portion, the side edges of any adjacent convex region 121 and concave region 122 can be connected to each other, so that all the convex regions 121 and concave regions 122 enclose the limiting portion 120, that is, the limiting portion 120 is a closed ring structure. Based on this, in the embodiment of the present application, the junction line of the convex region 121 and the concave region 122 also extends along the radial direction of the tray, and accordingly, each convex region 121 and each concave region 122 is a sector structure. In the case of using the technical solution disclosed in the embodiment, the area of the wafer 900 corresponding to each convex region 121 and each concave region 122 is a regular sector structure, so that the process uniformity of the wafer 900 can be further improved.

[0054] In a specific embodiment of the present application, taking the angle between the adjacent first crystal direction 910 and the second crystal direction 920 as 45° as an example, the angle across by the convex region 121 and the concave region 122 corresponding to the first crystal direction 910 and the second crystal direction 920 respectively can be 45°, and at the same time, the side edges connected to each other in the aforementioned convex region 121 and concave region 122 are located at the angle bisector of the first crystal direction 910 and the second crystal direction 920, so as to improve the thickness uniformity of the area corresponding to the first crystal direction 910 and the second crystal direction 920 in the epitaxial film layer of the wafer 900 as much as possible.

[0055] That is, in the embodiment of the present application, the second crystal direction 920 can coincide with the symmetry axis of the corresponding concave region 122, and accordingly, the first crystal direction 910 coincides with the symmetry axis of the corresponding convex region 121.

[0056] It is considered that the growth rate of the area across by the adjacent first crystal direction 910 and second crystal direction 920 is different from the area with different angles with the second crystal direction 920, specifically, the growth rate of the area with smaller angle with the second crystal direction 920 is slower. Therefore, in a further embodiment of the present application, the gas flow and other parameters at different positions in the concave region 122 corresponding to the second crystal direction 920 can be further adjusted by setting the flow guide portion 130.

[0057] In detail, in the embodiment of the present application, the tray 100 can further include a flow guide portion 130, and the concave region 122 can be provided with a plurality of flow guide portions 130 spaced along the circumferential direction of the limiting portion 120, and any flow guide portion 130 extends along the radial direction of the limiting portion 120, so as to ensure that the flow guide portion 130 can regulate the flow of the gas while basically not hindering the flow of the gas.

[0058] In a specific embodiment of the present application, as shown in FIG. 6, the flow guide portion 130 can be a protrusion extending along the radial direction of the limiting portion 120, and the protrusion can be arranged on the side edge of the limiting portion 120. Figure 5As shown, any guide flow portion 130 can be a strip structure extending along the radial direction of the limiting portion 120. Of course, during the arrangement of the guide flow portion 130, each guide flow portion 130 also needs to be directed to the center of the bearing portion 110, that is, the straight line in the extension direction of any guide flow portion 130 passes through the center of the bearing portion 110 (i.e., the center of the entire tray 100).

[0059] In another embodiment of the present application, as shown in Figure 6 The guide flow portion 130 can include a plurality of guide flow columns arranged in a straight line and spaced apart, that is, the plurality of guide flow columns are arranged in a straight line direction to collectively form the guide flow portion 130. Of course, the distribution direction of the guide flow columns included in each guide flow portion 130 on the recessed area 122 is parallel to the radial direction of the tray 100, and the distribution direction of the plurality of guide flow columns passes through the center of the tray 100. In the case of using the technical solution disclosed in the embodiment of the present application, the gas can flow along the circumferential direction of the guide flow column of the column body, that is, the gas can flow around the guide flow column, so that the gas flowing from the recessed area 122 to the wafer 900 as a whole can be divided into a plurality of strip-shaped gas flows, ensuring that the process effect between the area of the wafer 900 opposite to the guide flow portion 130 and the area of the wafer 900 not opposite to the guide flow portion 130 is the same or substantially the same, thereby further improving the process uniformity.

[0060] In addition, in the recessed area 122, the closer the area to the symmetry axis of the recessed area 122 in the circumferential direction of the limiting portion 120, the smaller the distribution density of the guide flow portion 130. In other words, in the embodiment of the present application, the sum of the angles between any two adjacent guide flow portions 130 and the second crystal direction 920 in the circumferential direction of the tray 100 is greater, and the angle between the two adjacent guide flow portions 130 is smaller.

[0061] In the case of using the above technical solution, the gas flow at different positions in the recessed area 122 can be further uniformly controlled, so that the gas flow at a position relatively close to the first crystal direction 910 in the recessed area 122 is less than the gas flow at a position relatively far from the first crystal direction 910 in the recessed area 122, so as to further improve the thickness uniformity of the epitaxial film layer at different positions in the wafer 900. It has been verified that, compared with the way of not differentiating the first crystal direction 910 and the second crystal direction 920, in the case of using the technical solution disclosed in the embodiment of the present application, as shown in Figure 7 The flatness curve of the epitaxial film layer can be improved from the first flatness curve S1 to the second flatness curve S2, so that the flatness is improved by at least 15 nm or more.

[0062] More specifically, for the specific value of the included angle between any two adjacent flow guiding portions 130, the difference of the growth rate at the positions corresponding to the first crystal direction 910 and the second crystal direction 920 can be flexibly determined according to the actual situation, which is not limited herein. In addition, the number and size of the flow guiding columns included in each flow guiding portion 130 and other parameters can also be determined according to the actual situation.

[0063] In a specific embodiment of the present application, each flow guiding column can be a regular structure such as a cylinder or a cube, or can also be an irregular columnar structure. Of course, in order to minimize the degree of obstruction of each flow guiding portion 130 to the process gas, in the embodiments of the present application, the arrangement direction of the plurality of flow guiding columns in any flow guiding portion 130 can be directed to the center of the wafer 900, so as to ensure that the flow guiding portion 130 has the control of the flow velocity of the gas while minimizing the obstruction effect of the flow guiding portion 130 to the gas, ensuring that the overall efficiency of the epitaxial process is still relatively high. At the same time, the upper surface of the flow guiding portion 130 can be flush with or slightly lower than the upper surface of the raised area 121, so as to prevent the flow guiding portion 130 provided in the recessed area 122 from causing the gas flow in the recessed area 122 to be less than that in the raised area 121.

[0064] Based on the tray 100 disclosed in any of the above embodiments, as shown in Figure 8 The present application also discloses a semiconductor device, which comprises a susceptor ring 200, a first cover 310, a second cover 320 and any of the above trays 100. The first cover 310 and the second cover 320 are respectively arranged above and below the susceptor ring 200 to form a process chamber with the susceptor ring 200. The susceptor ring 200 has a gas inlet hole 210 and a gas outlet hole 220, which are respectively located at opposite ends of the process chamber and are in communication with the process chamber. The tray 100 is arranged in the process chamber, and the wafer 900 can be carried on the tray 100, so that the process gas entering through the gas inlet hole 210 can flow through the upper surface of the wafer 900 and form an epitaxial film layer on the upper surface of the wafer 900.

[0065] Further, the semiconductor device can further include a preheating ring 500 sleeved outside the tray 100, and a first gasket 410 and a second gasket 420 oppositely arranged and both located inside the susceptor ring 200, the first gasket 410 being located above the gas inlet hole 210, and the second gasket 420 being located below the gas inlet hole 210, the preheating ring 500 and the tray 100 can be both installed on the second gasket 420, of course, the tray 100 can also be installed on a heating device, the heating device can be supported on the susceptor ring 200 and used to provide heating for the tray 100 and the wafer 900 to improve the epitaxy efficiency. In addition, the tray 100 can also be installed on a rotating shaft 600, of course, the rotating shaft 600 can be connected with a rotating motor or the like, the rotating shaft 600 can drive the tray 100 to rotate, so that the rotating shaft 600 can continuously drive the wafer 900 to rotate through the tray 100 in the process, thereby further improving the process uniformity of the wafer 900.

[0066] It should be noted that in this document, the terms "comprise", "comprising", or any other variant thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement "comprising a" does not exclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element. In addition, it should be pointed out that the scope of the methods and apparatus in the embodiments of the present application is not limited to performing functions in the order shown or discussed, but can also include performing functions in a substantially simultaneous manner or in reverse order, for example, the described method can be performed in an order different from that described, and various steps can also be added, omitted, or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0067] The embodiments of the present application are described above in combination with the drawings, but the present application is not limited to the above-described specific embodiments, which are only illustrative and not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims.

Claims

1. A pallet, characterized in that: The tray comprises a bearing portion (110) and a limiting portion (120) arranged around the bearing portion, wherein the bearing portion (110) has a concave surface (111) and a bearing surface (112) arranged around the concave surface; The carrying surface (112) is a plane, and is used to carry wafers; The concave surface (111) is arranged to be recessed relative to the bearing surface (112); The limiting portion is arranged to protrude relative to the bearing surface (112) toward a side away from the concave surface (111); The tray is further provided with a guide hole (113) penetrating the bearing portion (110), and the guide hole (113) extends to the concave surface (111).

2. The pallet according to claim 1, wherein: The limiting portion (120) includes a plurality of raised areas (121) and a plurality of recessed areas (122), wherein the plurality of raised areas (121) and the plurality of recessed areas (122) are alternately distributed along the circumference of the limiting portion (120), and in a direction perpendicular to the bearing surface (112), the upper surface of any recessed area (122) is lower than the upper surface of any raised area (121).

3. The pallet according to claim 2, wherein: The wafer (900) carried on the carrying surface (112) has a first crystal direction (910) and a second crystal direction (920); under the same epitaxial conditions, the growth rate of the region where the first crystal direction (910) is located is greater than the growth rate of the region where the second crystal direction (920) is located; In the radial direction of the wafer (900), the outer side of the first crystal direction (910) corresponds to the raised area (121), and the outer side of the second crystal direction (920) corresponds to the recessed area (122).

4. The pallet according to claim 2, wherein: The upper surface of the raised area (121) is higher than the upper surface of the wafer (900) carried on the carrying surface (112), and the upper surface of the recessed area (122) is lower than or flush with the upper surface of the wafer (900) carried on the carrying surface (112).

5. The pallet according to claim 2, wherein: The boundary line between the raised area (121) and the recessed area (122) extends along the radial direction of the tray.

6. The pallet according to claim 3, wherein: The recessed area (122) is a mirror-symmetrical structure, and the symmetry axis of the recessed area (122) extends along the radial direction of the tray.

7. The pallet according to claim 6, characterized in that The second crystal orientation direction (920) coincides with the symmetry axis of the corresponding recessed area (122).

8. The pallet according to any one of claims 2 to 7, characterized in that: The recessed area (122) is provided with a plurality of guide portions spaced apart along the circumference of the limiting portion (120), and any of the guide portions extends radially along the limiting portion (120).

9. The tray according to claim 8, characterized in that: Any of the guide portions (130) comprises a plurality of guide columns arranged at intervals along the radial direction of the tray.

10. The pallet according to claim 8, wherein: The recessed area (122) is a mirror-symmetrical structure, and in the recessed area (122), the closer the area is to the symmetry axis of the recessed area (122) in the circumferential direction of the limiting portion, the smaller the distribution density of the guide portion (130).

11. The pallet according to claim 1, wherein: The flatness of the bearing surface (112) is less than or equal to 0.1 mm.

12. The pallet according to claim 11, wherein: The roughness of the bearing surface (112) is between 0.5um and 2um.

13. The pallet according to claim 10, wherein: In a direction perpendicular to the bearing surface (112), the distance between the center of the concave surface and the bearing surface (112) is less than or equal to 0.3 mm.

14. A semiconductor device, characterized in that: Comprising a base ring (200), a first cover (310), a second cover (320), and a tray (100) according to any one of claims 1 to 13; The first cover body (310) and the second cover body (320) are respectively arranged above and below the base ring (200) to enclose a process chamber with the base ring (200); The tray (100) is arranged in the process chamber; The base ring (200) has an air inlet (210) and an exhaust hole (220), the air inlet (210) and the exhaust hole (220) are respectively located at opposite ends of the process chamber, and the air inlet (210) and the exhaust hole (220) are both connected to the process chamber.

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