Silicon carbide tray for rapid heat treatment and rapid heat treatment method

Abstract

The invention provides a silicon carbide tray for rapid heat treatment and a rapid heat treatment method.The silicon carbide tray for rapid heat treatment comprises a silicon carbide base disc, and the silicon carbide base disc is provided with at least three sets of cooling table limiting openings, wafer limiting columns and through holes; the cooling table limiting opening, the wafer limiting column and the through hole are respectively arranged on the silicon carbide basal disc at equal intervals, the distance between the cooling table limiting opening and the center of the silicon carbide basal disc is a, the distance between the wafer limiting column and the center of the silicon carbide basal disc is b, and the distances between the through hole and the center of the silicon carbide basal disc are c and egt; bgt; c. According to the invention, silicon carbide is made into a tray for rapid heat treatment with a special structure, so that the wafer heating uniformity can be improved, the edge effect and the pattern loading effect in the wafer heating process are reduced, and an oxidation film with higher quality is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer processing and relates to a silicon carbide tray for rapid thermal processing and a rapid thermal processing method. Background Art

[0002] In the integrated circuit manufacturing process, there are two methods for forming silicon oxide films: thermal oxidation and deposition. The oxidation process refers to the process of forming silicon dioxide (SiO2) on the surface of a silicon wafer by thermal oxidation. The silicon dioxide film formed by thermal oxidation is widely used in the integrated circuit manufacturing process because of its superior electrical insulation and process feasibility. Its most important use is as a gate dielectric in the MOS device structure. Other uses include device protection and isolation, surface passivation treatment, ion implantation masking layer, diffusion barrier layer, buffer layer between silicon and other materials, etc.

[0003] In order to avoid the introduction of a high thermal budget (Thermal Budget), which causes the redistribution of impurities in the silicon wafer and leads to the degradation of device performance, in the high-k metal gate process of the last high-k (High-kLast), the rapid thermal oxidation (Rapid Thermal Oxidation, RTO) method is generally used to grow the gate dielectric ultra-thin interface layer (Interfacial Laver). The heating / cooling rate in rapid thermal oxidation is 100 to 1000 times faster than that of traditional tubular thermal oxidation, reducing the thermal budget in the heating / cooling process. In order to reduce the edge effect (faster edge heat dissipation leads to a difference in center and edge temperature) and pattern loading effect during wafer heating.

[0004] CN107034516A discloses a susceptor for use in an epitaxial growth chamber and a heat conduction block for holding a wafer, wherein the main body includes a first region, a second region, and a third region. The first region extends a first width inward from the outer edge of the main body toward the center of the main body, and the first region has a first height. The second region extends a second width inward from the inner edge of the first region toward the center of the main body, and the second region has a second height lower than the first height. The third region extends from the inner edge of the second region to the center of the main body. The second region includes a flat surface substantially parallel to the bottom surface of the substrate, and a portion of the bottom surface of the substrate is placed on the flat surface.

[0005] CN113517192A discloses a wafer processing method and a method for manufacturing a semiconductor device. The wafer processing method comprises: arranging a protective member having at least one through hole at the edge or the vicinity of the wafer, wherein the at least one through hole corresponds to at least the edge portion of the wafer; performing heat treatment on the wafer using heat radiated by a heating device, wherein a portion of the heat passes through the at least one through hole to heat the edge portion of the wafer, and another portion of the heat directly heats the rest of the wafer except the edge portion.

[0006] The above solution improves the heat treatment effect of the wafer by changing the structural composition of the heat treatment device, but the structure of the device is complex and the improvement effect is general, and the practicality is poor. Summary of the invention

[0007] The object of the present invention is to provide a silicon carbide tray for rapid thermal processing and a rapid thermal processing method. The present invention makes silicon carbide into a rapid thermal processing tray with a special structure, which can improve the uniformity of wafer heating, reduce the edge effect and pattern loading effect during wafer heating, and obtain a higher quality oxide film.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a silicon carbide tray for rapid thermal processing, the silicon carbide tray for rapid thermal processing comprising a silicon carbide base plate, at least three groups of cooling table limit openings, wafer limit columns and through holes are arranged on the silicon carbide base plate, the cooling table limit openings, wafer limit columns and through holes are equally divided and arranged on the silicon carbide base plate, wherein the distance between the cooling table limit opening and the center of the silicon carbide base plate is a, the distance between the wafer limit column and the center of the silicon carbide base plate is b, the distance between the through hole and the center of the silicon carbide base plate is c, and a>b>c.

[0010] The equal division arrangement described in the present invention is to divide the silicon carbide substrate into several equal parts, each part is equal, and corresponding structures (cooling table limit openings, wafer limit columns and through holes) are respectively arranged at the same position from the center in each part.

[0011] The cooling platform limit opening of the present invention can be set according to the position of the cooling platform pillars, but there are at least three, otherwise instability will occur. The wafer limit column can also be modified according to the diameter of the wafer to be processed, and the wafer only needs to be fixed. The through hole needs to be set inside the wafer limit column so that it can be covered by the wafer, and the wafer can be ejected by the ejector pin through the through hole after subsequent cooling.

[0012] The shape of the silicon carbide tray of the present invention includes but is not limited to a circle, and can be modified according to actual needs.

[0013] The present invention utilizes the advantages of silicon carbide such as high thermodynamic stability, good thermal conductivity, high electron mobility, oxidation resistance, and corrosion resistance, and sets up a silicon carbide tray for rapid thermal processing with a special structure. The silicon carbide tray for rapid thermal processing can make the entire surface of the wafer heated more evenly during the heating process of the wafer, avoid edge effects during the heating process, and obtain a higher quality oxide film. During the cooling process after heating, the temperature can be quickly reduced, greatly reducing the cooling time. The special design of the limit column and the through hole also facilitates the separation of the wafer from the tray.

[0014] The silicon carbide tray described in the present invention can also be made of graphite coated with silicon carbide. Although the cost of graphite coated with silicon carbide is low, its service life is short. After a long time, the silicon carbide coating on the surface is easy to fall off, causing the internal graphite structure to loosen and easily fall off on the wafer surface.

[0015] Preferably, the silicon carbide substrate further includes wafer anti-sticking bumps which are equally spaced.

[0016] Preferably, the distance between the wafer anti-sticking bump and the center of the silicon carbide substrate is d, d <b。

[0017] Preferably, the height of the wafer anti-sticking bumps is 0.1-3 mm, for example, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm or 0.3 mm, etc., and is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the number of the wafer anti-sticking bumps is ≥6.

[0019] The wafer anti-sticking bumps of the present invention can prevent the wafer from sticking to the tray under high temperature conditions, so they need to be evenly distributed on the silicon carbide base plate, but still need to be distributed on the inner side of the wafer limiting pillars.

[0020] Preferably, the wafer limiting pillars and the through holes are distributed in a straight line toward the center of the silicon carbide tray.

[0021] The wafer limiting pillars and through holes of the present invention are distributed in a straight line toward the center, that is, the wafer limiting pillars and through holes are on a straight line, and the straight line passes through the center of the silicon carbide tray.

[0022] Preferably, the height of the wafer limiting column is 0.4-0.6 mm, for example, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm or 0.6 mm, etc., and is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the diameter of the silicon carbide substrate is 100-300 mm, for example, 100 mm, 150 mm, 200 mm, 250 mm or 300 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the thickness of the silicon carbide substrate is 1 to 2 mm, for example, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm or 2 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In a second aspect, the present invention provides a rapid thermal processing method, wherein the rapid thermal processing method uses the silicon carbide tray for rapid thermal processing as described in the first aspect, and the rapid thermal processing method comprises the following steps:

[0026] A wafer of a suitable size is placed between wafer limiting columns of a silicon carbide tray for rapid thermal processing to obtain an assembly, and the assembly is placed in a heating device for rapid oxidation processing;

[0027] The cooling table limit sleeve of the assembly is placed on the cooling table for cooling. After cooling, the wafer is lifted up by a pin through the through hole to complete the rapid heat treatment.

[0028] Preferably, during the rapid oxidation process, heating is performed on both the upper and lower sides of the assembly.

[0029] Preferably, the temperature of the rapid oxidation treatment is 900-1200°C, for example, 900°C, 950°C, 1000°C, 1100°C or 1200°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the temperature of the cooling treatment is 200-300°C, for example, 200°C, 220°C, 250°C, 280°C or 300°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The silicon carbide tray for rapid thermal processing of the present invention has the advantages of high thermodynamic stability, good thermal conductivity, high electron mobility, anti-oxidation, corrosion resistance, etc. It is easy to use and significantly improves the thermal treatment effect. It can be directly cleaned and reused after use.

[0033] (2) The rapid thermal treatment method of the present invention has high temperature consistency during continuous operation and better uniformity between sheets. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a plan view of the silicon carbide tray for rapid heat treatment of the present invention, 1-silicon carbide base plate, 2-cooling platform limiting opening, 3-wafer limiting column, 4-through hole, 5-wafer anti-sticking bump.

[0035] Figure 2 This is the temperature change curve of the wafer in the method for rapid thermal treatment of the wafer described in Example 1.

[0036] Figure 3 This is a temperature change curve of the wafer in the method for rapid thermal treatment of the wafer described in Example 1.

[0037] Figure 4 The uniformity fitting curves of the wafers obtained by the rapid thermal treatment of the wafers described in Example 1 and Comparative Example 1 are shown.

[0038] Figure 5 The thermal analysis diagram of the wafer is obtained by the method for rapid thermal treatment of the wafer described in the first group of experiments in Example 1.

[0039] Figure 6 The thermal analysis diagram of the wafer is obtained by the method for rapid thermal treatment of the wafer described in the second group of experiments in Example 1.

[0040] Figure 7 This is the thermal analysis diagram of the wafer obtained by the method for rapid thermal treatment of the wafer described in the third group of experiments in Example 1.

[0041] Figure 8 This is a thermal analysis diagram of a wafer obtained by the method for rapid thermal treatment of the wafer described in the first group of experiments in Example 1.

[0042] Fig. 9 This is a thermal analysis diagram of a wafer obtained by the method for rapid thermal treatment of the wafer described in the second group of experiments in Example 1.

[0043] Fig.10 This is a thermal analysis diagram of a wafer obtained by the method for rapid thermal treatment of the wafer described in the third group of experiments in Example 1. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] The structural schematic diagram of the silicon carbide tray for rapid thermal processing used in the embodiment of the present invention is as follows Figure 1As shown, the silicon carbide tray for rapid thermal processing is circular, the cooling table limiting opening 2, wafer limiting pillar 3, through hole 4 and wafer anti-sticking convex point 5 of the silicon carbide tray for rapid thermal processing are independently and equally divided on the silicon carbide base plate 1, the number of the cooling table limiting opening 2, the wafer limiting pillar 3 and the through hole 4 are 3, the number of the wafer anti-sticking convex point 5 is 6, the diameter of the silicon carbide base plate 1 is 200mm, the height of the wafer limiting pillar 3 is 0.5mm, the height of the wafer anti-sticking convex point 5 is 0.2mm, the distance between the cooling table limiting opening 2 and the center of the silicon carbide base plate 1 is a, the distance between the wafer limiting pillar 3 and the center of the silicon carbide base plate 1 is b, the distance between the through hole 4 and the center of the silicon carbide base plate 1 is c, a>b>c, the distance between the wafer anti-sticking convex point 5 and the center of the silicon carbide base plate 1 is d, d <b。

[0046] Example 1

[0047] This embodiment provides a method for rapid thermal processing of a wafer, the method comprising the following steps:

[0048] The silicon wafer is placed between the wafer limiting pillars 3 of the silicon carbide tray for rapid thermal processing to obtain an assembly, and the assembly is placed in a heating device for rapid oxidation treatment (the maximum temperature is set to 1000° C., and the holding time is 30 seconds);

[0049] The cooling platform limit opening 2 of the assembly is placed on the cooling platform and cooled to 200° C. After cooling, the wafer is lifted up by a pin through the through hole 4 to complete the rapid thermal treatment.

[0050] Rapid thermal treatment temperature change curve Figure 2 shown.

[0051] Example 2

[0052] This embodiment provides a method for rapid thermal processing of a wafer, the method comprising the following steps:

[0053] The silicon wafer is placed between the wafer limiting pillars 3 of the silicon carbide tray for rapid thermal processing to obtain an assembly, and the assembly is placed in a heating device for rapid oxidation treatment (the maximum temperature is set to 1200° C., and the holding time is 90 seconds);

[0054] The cooling platform limit opening 2 of the assembly is placed on the cooling platform and cooled to 200° C. After cooling, the wafer is lifted up by a pin through the through hole 4 to complete the rapid thermal treatment.

[0055] Under the condition of a certain oxygen flow rate, the oxidation rate reaches the fastest at 1200°C and the density of the film layer will be better.

[0056] Example 3

[0057] This embodiment provides a method for rapid thermal processing of a wafer, the method comprising the following steps:

[0058] The silicon wafer is placed between the wafer limiting pillars 3 of the silicon carbide tray for rapid thermal processing to obtain an assembly, and the assembly is placed in a heating device for rapid oxidation treatment (the maximum temperature is set to 900° C., and the holding time is 60 seconds);

[0059] The cooling platform limit opening 2 of the assembly is placed on the cooling platform and cooled to 200° C. After cooling, the wafer is lifted up by a pin through the through hole 4 to complete the rapid thermal treatment.

[0060] At this time, the temperature is low, the oxidation rate is slow, and the density of the film layer is poor, but the heating uniformity is still good.

[0061] Example 4

[0062] This embodiment provides a method for rapid thermal processing of a wafer, the method comprising the following steps:

[0063] The silicon wafer is placed between the wafer limiting pillars 3 of the silicon carbide tray for rapid thermal processing to obtain an assembly, and the assembly is placed in a heating device for rapid oxidation treatment (the maximum temperature is set to 1400° C., and the holding time is 20 seconds);

[0064] The cooling platform limit opening 2 of the assembly is placed on the cooling platform and cooled to 200° C. After cooling, the wafer is lifted up by a pin through the through hole 4 to complete the rapid thermal treatment.

[0065] If the heat treatment temperature is too high, the tray may break occasionally. Analysis shows that the temperature resistance of the silicon carbide tray structure has reached its upper limit.

[0066] If the heating rate during heat treatment is too fast, occasional tray breakage may occur. Analysis shows that this may be caused by excessive thermal expansion due to rapid heating.

[0067] Comparative Example 1

[0068] In this comparative example, the silicon wafer is directly subjected to rapid thermal treatment. The temperature variation curve of the rapid thermal treatment is as follows: Figure 3 shown.

[0069] Depend on Figure 2 and Figure 3 By comparison, it can be seen that during the bare Si process, the edge temperature is lower than the center, and there is an overshoot phenomenon of 3 to 4 seconds in the stage of heating to constant temperature conversion, and the overshoot temperature is about 20°C. However, when using the silicon carbide tray for rapid thermal treatment of the present invention, there is basically no overshoot during the rapid thermal treatment, and the temperature curves of the inner and outer circles are basically overlapped, but the time spent on cooling from 1000°C to 200°C is about 50s longer than that of bare Si.

[0070] Repeated comparative experiments were conducted on Example 1 and Comparative Example 1, respectively, with 13 points as the test method, 5 mm edge removal, and U% (uniformity of film thickness between sheets) = (Max (maximum film thickness) - Min (minimum film thickness)) / (2*Mean (average film thickness))). The results of the repeated comparisons are shown in Table 1, and the uniformity data comparison diagram is shown in Table 1. Figure 4 As shown:

[0071] Table 1

[0072]

[0073] From the comparison of Examples 1-4, it can be seen that the silicon carbide tray for rapid thermal processing of the present invention has a wide application temperature and can achieve rapid thermal oxidation of wafers at 900-1200°C. However, if the temperature is too high, there may be a risk of breakage of the silicon carbide tray, and preheating treatment is required.

[0074] The uniformity fitting curves of Example 1 and Comparative Example 1 are as follows: Figure 4 As shown by Figure 4 It can be seen that the uniformity of rapid thermal treatment of wafers using the silicon carbide tray for rapid thermal treatment of the present invention is high, indicating that the stability of the rapid thermal treatment method of the present application is greatly improved compared to the conventional wafer rapid thermal oxidation method.

[0075] The thermal (film thickness) analysis diagrams of the wafer obtained by the method for rapid thermal treatment of the wafer in Example 1 are as follows: Figure 5-7 As shown, the thermal (film thickness) analysis diagrams of the wafers obtained by the rapid thermal treatment method of the wafer in Comparative Example 1 are as follows: Figure 8-10 As shown by Figure 5-10 By comparison, it can be seen that the use of a tray can not only optimize the uniformity of film thickness within the wafer, but also the uniformity between wafers is 0.12% when using a tray and 0.64% when not using a tray, indicating that the stability of the tray is much better than that of bare wafer operation.

[0076] In summary, the present invention utilizes the advantages of silicon carbide such as high thermodynamic stability, good thermal conductivity, high electron mobility, oxidation resistance, and corrosion resistance, and sets up a silicon carbide tray for rapid thermal processing with a special structure. The silicon carbide tray for rapid thermal processing can make the entire surface of the wafer heated more evenly during the heating process of the wafer, avoid edge effects during the heating process, and obtain a higher quality oxide film. During the cooling process after heating, the temperature can be quickly reduced, greatly reducing the cooling time. The special design of the limit column and the through hole also facilitates the separation of the wafer from the tray.

[0077] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A rapid heat treatment silicon carbide tray, characterized in that: The silicon carbide tray for rapid thermal processing includes a silicon carbide base plate, on which at least three groups of cooling table limit openings, wafer limit columns and through holes are arranged, and the cooling table limit openings, wafer limit columns and through holes are equally divided and arranged on the silicon carbide base plate, wherein the distance between the cooling table limit opening and the center of the silicon carbide base plate is a, the distance between the wafer limit column and the center of the silicon carbide base plate is b, and the distance between the through hole and the center of the silicon carbide base plate is c, and a>b>c.

2. The silicon carbide tray for rapid thermal processing according to claim 1, characterized in that: The silicon carbide substrate also includes wafer anti-sticking bumps that are equally spaced.

3. The silicon carbide tray for rapid thermal processing according to claim 2, characterized in that: The distance between the wafer anti-sticking bump and the center of the silicon carbide substrate is d, d <b。 4. The silicon carbide tray for rapid thermal processing according to claim 3, characterized in that: The height of the wafer anti-sticking bumps is 0.1 mm to 0.3 mm; The number of the wafer anti-sticking bumps is ≥6.

5. The silicon carbide tray for rapid thermal processing according to claim 1, characterized in that: The wafer limiting pillars and through holes are distributed in a straight line toward the center of the silicon carbide tray.

6. The silicon carbide tray for rapid thermal processing according to claim 1, characterized in that: The height of the wafer limiting column is 0.4-0.6 mm.

7. The silicon carbide tray for rapid thermal processing according to claim 1, characterized in that: The diameter of the silicon carbide substrate is 100-300 mm.

8. The silicon carbide tray for rapid thermal processing according to claim 1, characterized in that: The thickness of the silicon carbide substrate is 1 to 2 mm.

9. A rapid thermal treatment method, characterized in that: The rapid thermal processing method uses the silicon carbide tray for rapid thermal processing according to any one of claims 1 to 8, and the rapid thermal processing method comprises the following steps: Placing a wafer of a suitable size between wafer limiting columns of a silicon carbide tray for rapid thermal processing to obtain an assembly, and placing the assembly in a heating device for rapid oxidation processing; The cooling table limit sleeve of the assembly is placed on the cooling table for cooling. After cooling, the wafer is lifted up by a pin through the through hole to complete the rapid heat treatment.

10. The rapid thermal processing method according to claim 9, characterized in that: During the rapid oxidation process, heating is performed on both the upper and lower sides of the assembly; And / or, the temperature of the rapid oxidation treatment is 900-1200°C; And / or, the cooling treatment temperature is 200-300°C.

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