LPCVD furnace tube structure
By designing a second insulation barrel and a second insulation sheet with adjustment function in the LPCVD furnace tube structure, the problems of damage to quartz parts and thin film during the PM process are solved, and the yield of the product is improved.
Patent Information
- Application Number
- CN202421844472.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-05-06
- Estimated Expiration
- 2034-07-31
AI Technical Summary
In LPCVD silicon nitride furnace tubes, regular maintenance (PM) process will damage the quartz parts inside the furnace tube, resulting in the thin film layer of the top wafer during the first run after PM, affecting the product yield.
An LPCVD furnace tube structure is designed, including a pipe body, a crystal boat, a first insulation barrel and a second insulation barrel. By providing a second insulation sheet with different surface roughness in the second insulation barrel, the sum of the surface areas of the upper end and the lower end of the tube body is adjusted to reduce damage during PM and avoid the occurrence of thin film layer.
It effectively reduces damage to the quartz parts inside the furnace tube during the PM process, avoids the occurrence of thin film layer, and improves the yield of the product.
Smart Images
Figure CN222834392U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of semiconductor manufacturing, in particular to a LPCVD furnace tube structure. Background Art
[0002] When a silicon nitride film is deposited on the surface of the wafer using a low-pressure chemical vapor deposition (LPCVD) silicon nitride furnace tube, a silicon nitride film is also deposited on the inner wall of the furnace tube. Due to the high stress of the silicon nitride film, when the film layer accumulated on the inner wall of the furnace tube reaches a certain thickness, the film layer is prone to peeling, which in turn causes particle contamination in the furnace. Therefore, it is necessary to perform regular maintenance (Plan Maintain, PM) on the inside of the furnace tube by introducing clean gas into the furnace tube to remove the film layer on the inner wall of the furnace. Conventionally, when the film layer in the furnace tube reaches a certain cumulative thickness, the machine automatically executes the PM process. However, each PM of the machine will damage the quartz parts inside the furnace tube. When the machine executes the PM process for a certain number of times, when the furnace tube is used to deposit silicon nitride thin film on the wafer surface, the film layer of the top wafer in the furnace tube will be obviously thinner when the thin film deposition is run for the first time after PM, which will lead to an increase in the difference range of the entire batch of products. As the number of PM times of the machine increases, the thinning phenomenon of the film layer of the top wafer in the first thin film deposition run after PM becomes more and more serious, and the difference range of the entire batch of products becomes larger, which seriously affects the yield of the product.
[0003] Therefore, how to provide a LPCVD furnace tube structure that can reduce the impact of PM on the top wafer film thickness is an urgent problem to be solved. Utility Model Content
[0004] The technical problem to be solved by the utility model is to provide a LPCVD furnace tube structure to reduce the influence of PM on the film thickness of the top wafer.
[0005] In order to solve the above problems, the utility model provides an LPCVD furnace tube structure, which includes a tube body, in which: a wafer boat is provided for placing wafers, the wafer boat includes a plurality of slots stacked along a first direction, each of the slots can hold a wafer, and the first direction is perpendicular to the bottom surface of the tube body; a first insulation barrel, connected to the bottom of the wafer boat, the first insulation barrel is provided with a plurality of first support layers stacked along the first direction, and a first insulation sheet can be placed on the first support layer; a second insulation barrel, connected to the top of the wafer boat, the second insulation barrel is provided with a plurality of second support layers stacked along the first direction, a second insulation sheet can be placed on the second support layer, and the same second support layer can be provided with second insulation sheets with different surface roughnesses.
[0006] In some embodiments, the inner wall of the tube is made of quartz.
[0007] In some embodiments, the tube is cylindrical.
[0008] In some embodiments, the gas flow direction in the tube body is parallel to the bottom surface of the tube body, and the gas flow rates at the top and bottom of the tube body are the same.
[0009] In some embodiments, a surface of the second thermal insulation sheet facing the top of the tube body is a rough surface.
[0010] In some embodiments, the second thermal insulation sheet has a plurality of different specifications, and the surface roughness of the second thermal insulation sheet of different specifications is different.
[0011] In some embodiments, the roughness of the rough surface of the second thermal insulation sheet is selected to be opposite to the roughness of the inner wall material of the tube body.
[0012] In some embodiments, the first insulation barrel has the same structure as the second insulation barrel.
[0013] In some embodiments, the distance between adjacent second supporting layers is adjustable.
[0014] In some embodiments, the second thermal insulation sheet is made of quartz.
[0015] According to the above technical solution, a crystal boat, a first insulation barrel and a second insulation barrel are arranged in the tube body of the furnace tube structure, the crystal boat includes a plurality of slots stacked along a first direction, the first direction is perpendicular to the bottom surface of the tube body, the first insulation barrel is connected to the bottom of the crystal boat, the second insulation barrel is connected to the top of the crystal boat, the second insulation barrel is provided with a plurality of second support layers stacked along the first direction, a second insulation sheet can be placed on a second support layer, and a second insulation sheet with different surface roughness can be arranged on the same second support layer. The second insulation barrel is adjusted to make the sum of the surface areas of the quartz parts at the upper and lower ends of the tube body equivalent, so that the damage of the quartz parts in the furnace tube can be reduced during PM, and the occurrence of thin silicon nitride film deposited on the surface of the wafer located at the upper end of the tube body when the silicon nitride film is deposited can be avoided, thereby improving the yield of the product.
[0016] It should be understood that the above general description and the detailed description below are only exemplary and explanatory and cannot limit the present invention. The techniques, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the techniques, methods and devices should be considered as part of the authorization specification. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments of the utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0018] Figure 1 This is a schematic diagram of the device structure of the LPCVD furnace tube structure provided by one embodiment of the utility model;
[0019] Figure 2 It is a schematic diagram of the device structure of the second heat preservation barrel provided in one embodiment of the utility model;
[0020] Figure 3A , Figure 3B , Figure 3C It is a cross-sectional schematic diagram of second thermal insulation sheets of different specifications provided in one embodiment of the utility model. DETAILED DESCRIPTION
[0021] The technical solutions in the embodiments of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0022] Through the analysis of the furnace tube structure after PM, it was found that the film layer of the top wafer that performed the thin film deposition for the first time after PM was thin. This was because the roughness of the quartz component at the upper end of the tube body after PM was significantly different from the roughness of the quartz component at the lower end of the tube body. The roughness of the quartz component at the upper end of the tube body after PM was greater than the roughness of the quartz component at the lower end. When silicon nitride film deposition is performed again, and the flow rates of the reaction gas at the upper and lower ends of the tube body are the same, the quartz component with a large roughness at the upper end of the tube body consumes significantly more reaction gas than the quartz component at the lower end of the tube body, which in turn causes the silicon nitride film deposited on the surface of the wafer at the upper end of the tube body to become thinner. Therefore, the present application provides a new LPCVD furnace tube structure.
[0023] Figure 1 Schematic diagram of the device structure of the LPCVD furnace tube structure provided by one embodiment of the utility model. Figure 1As shown, the furnace tube structure includes a tube body 1, and the tube body 1 is provided with: a wafer boat 11, a first heat preservation barrel 12, and a second heat preservation barrel 13. The wafer boat 11 is used to place wafers, and the wafer boat 11 includes a plurality of slots stacked along a first direction Y, each of which can hold a wafer, and the first direction Y is perpendicular to the bottom surface of the tube body 1; the first heat preservation barrel 12 is connected to the bottom of the wafer boat 11, and the first heat preservation barrel 12 is provided with a plurality of first support layers stacked along the first direction Y, and a first heat preservation sheet can be placed on the first support layer; the second heat preservation barrel 13 is connected to the top of the wafer boat 11, and the second heat preservation barrel 13 is provided with a plurality of second support layers stacked along the first direction Y, and a second heat preservation sheet can be placed on the second support layer, and the same second support layer can be provided with second heat preservation sheets with different surface roughness. When the first thermal insulation sheet is placed in the first supporting layer, the first thermal insulation sheet is parallel to the bottom surface of the tube body 1 ; when the second thermal insulation sheet is placed in the second supporting layer, the second thermal insulation sheet is parallel to the bottom surface of the tube body 1 .
[0024] In this embodiment, the tube body 1 is used to deposit a silicon nitride film on the surface of a wafer. The inner wall of the tube body 1 is made of quartz. The tube body 1 is cylindrical. The gas flow direction in the tube body 1 is ( Figure 1 Gas direction) is parallel to the bottom surface of the tube body 1, and the gas flow rates at the top and bottom of the tube body 1 are the same.
[0025] In this embodiment, the first insulation sheet in the first insulation barrel 12 and the second insulation sheet in the second insulation barrel 13 are both made of quartz, which is the same material as the inner wall of the tube body 1 .
[0026] Figure 2 Schematic diagram of the device structure of the second heat preservation barrel provided by one embodiment of the utility model. Figure 2 As shown, the second heat preservation barrel 13 is provided with a plurality of second support layers 131 stacked along the first direction Y, and a second heat preservation sheet is placed on each of the second support layers 131. Specifically, the second heat preservation barrel 13 includes a plurality of support columns 132 ( Figure 2 3 support columns are shown in the figure), each support column 132 is provided with a plurality of support sheets 133, and the plurality of support sheets 133 are integrally formed with the support column 132, and the support sheets 133 on different support columns 132 form a plane, and the second thermal insulation sheet 19 can be placed on the plane formed by the support sheets 133. Each second support layer 131 includes a section of each support column 132, the support sheet 133 and the second thermal insulation sheet 19, as shown in FIG. Figure 2 As shown in the dashed box.
[0027] like Figure 2As shown, the surface of the second thermal insulation sheet 19 facing the top of the tube body is a rough surface, that is, the surface of the second thermal insulation sheet 19 along the first direction Y is a rough surface. The surface in the opposite direction of the first direction Y is a relatively smooth surface, so that the second thermal insulation sheet 19 can be stably placed on the plane formed by the support sheet 133.
[0028] The second thermal insulation sheet 19 has a variety of different specifications, and the surface roughness of the second thermal insulation sheet 19 of different specifications is different. Figure 3A , Figure 3B , Figure 3C It is a cross-sectional schematic diagram of second thermal insulation sheets of different specifications provided in one embodiment of the utility model.
[0029] In this embodiment, the second thermal insulation sheet has three different specifications, namely low roughness, medium roughness, and high roughness, and the material of the second thermal insulation sheet is quartz. Figure 3A A cross-sectional schematic diagram of the second thermal insulation sheet 191 with low roughness is shown in FIG. Figure 3A As shown, the surface of the second insulation sheet 191 with low roughness is relatively flat, almost flat; Figure 3B A cross-sectional schematic diagram of a second thermal insulation sheet 192 with medium roughness is shown in FIG. Figure 3B As shown, the surface of the second insulation sheet 192 with medium roughness is uneven and has obvious undulations; Figure 3C A schematic cross-sectional view of a second thermal insulation sheet 193 having a high roughness is shown in FIG. Figure 3C As shown, the undulations on the surface of the second thermal insulation sheet 193 with high roughness are more obvious. The surface areas of the second thermal insulation sheets with different roughness are different. The greater the roughness, the greater the surface area of the second thermal insulation sheet.
[0030] In this embodiment, the distance between adjacent second supporting layers 131 is fixed, and the distance can meet the placement requirements of second thermal insulation sheets with different surface roughness. Figure 2 The roughness of the second thermal insulation sheets 19 in different second supporting layers 131 is different. In another embodiment, the roughness of the second thermal insulation sheets 19 in different second supporting layers 131 is exactly the same.
[0031] In some embodiments, the distance between adjacent second support layers 131 is adjustable. Specifically, the support column and the support sheet are detachable, and each support column is provided with a plurality of clamping points. One end of the support sheet includes a connector, and the support sheet is fixed to the support column by inserting the connector into the clamping point. By inserting the connector of the support sheet into different clamping points, the distance between two adjacent support sheets on the support column can be adjusted, thereby adjusting the distance between the planes formed by the support sheets of the support column, and further adjusting the distance between adjacent second support layers 131.
[0032] In this embodiment, second insulation sheets of different specifications can be selected according to the machine conditions. For example, when the quartz piece inside the tube body 1 of the furnace tube structure is new, a second insulation sheet 193 with high roughness is selected and placed in the second insulation barrel 13, so that the total surface area of the quartz piece at the upper end of the tube body 1 is equivalent to the total surface area of the quartz piece at the lower end. When the tube body 1 performs a silicon nitride deposition process, the reaction gas will deposit a silicon nitride film on the surface of the quartz piece of the tube body 1, that is, a silicon nitride film is deposited on the upper and lower ends of the inner wall of the tube body 1, the surface of the first insulation sheet in the first insulation barrel 12, and the surface of the second insulation sheet in the first insulation barrel 12, and the thickness of the silicon nitride film on the surface of the quartz piece at the upper and lower ends of the tube body 1 is equivalent.
[0033] When the tube body 1 performs the PM process, the flow direction of the cleaning gas in the tube body 1 is parallel to the bottom surface of the tube body 1, and the gas flow rate of the cleaning gas at the top and bottom of the tube body 1 is the same. Since the area and thickness of the silicon nitride film at the upper and lower ends of the furnace tube 1 are comparable, during PM, the cleaning speeds of the silicon nitride film on the inner walls of the upper and lower ends of the tube body 1 are substantially the same. Furthermore, it avoids the phenomenon that after the silicon nitride film at the upper end of the tube body 1 is cleaned, the lower end of the tube body 1 still needs a long cleaning time, thereby avoiding the cleaning gas from damaging the inner wall of the upper end of the tube body 1 after cleaning. In addition, it avoids the problem of excessively large difference in roughness between the inner walls of the upper and lower ends of the tube body 1 after PM, and avoids the phenomenon of thin film layer on the top wafer that performs the first film deposition after PM.
[0034] In this embodiment, the roughness of the rough surface of the second insulation sheet is selected to be opposite to the roughness of the inner wall material of the tube body. For example, as the number of PM times of the furnace tube structure increases, the roughness of the surface of the quartz part inside the tube body 1 increases, and the insulation sheet in the second insulation barrel 13 can be replaced with a second insulation sheet 192 with a medium roughness or a second insulation sheet 191 with a low roughness, which has a smaller roughness, to balance the total surface area of the quartz parts at the upper and lower ends of the tube body 1. When the tube body 1 performs a silicon nitride deposition process, the thickness of the silicon nitride film deposited on the surface of the quartz parts in the upper and lower ends of the tube body 1 is equivalent; and when the tube body 1 performs a PM process, the cleaning speed of the silicon nitride film on the inner wall of the upper and lower ends of the tube body 1 is basically the same. In this way, the problem of excessively large difference in the roughness of the inner wall of the upper and lower ends of the tube body 1 is avoided, and the phenomenon of thin film layer on the top wafer that performs the first film deposition after PM is avoided.
[0035] In some embodiments, the first insulation barrel has the same structure as the second insulation barrel. The same structure here does not require that the first insulation barrel and the second insulation barrel have exactly the same structural dimensions, but means that: the first insulation sheets have different specifications, and the first insulation sheets of different specifications correspond to different roughnesses, and the distance between adjacent first support layers in the first insulation barrel can set the first insulation sheets with different surface roughnesses. The roughness of the insulation sheets in the first insulation barrel and the second insulation barrel can be adjusted, and the quartz surface area at the upper and lower ends of the tube body can be adjusted more accurately, so as to avoid excessive differences in the thickness of the silicon nitride film deposited on the wafer surface at the upper and lower ends of the tube body when the silicon nitride film is deposited.
[0036] According to the above technical solution, a wafer boat, a first insulation barrel and a second insulation barrel are arranged in the tube body of the furnace tube structure, the wafer boat includes a plurality of slots stacked along a first direction, each of the slots can hold a wafer, the first direction is perpendicular to the bottom surface of the tube body, the first insulation barrel is connected to the bottom of the wafer boat, the second insulation barrel is provided with a plurality of second support layers stacked along the first direction, a second insulation sheet can be placed on a second support layer, and a second insulation sheet with different surface roughness can be provided on the same second support layer. The second insulation barrel and the second insulation sheets with different roughnesses are adjusted to make the sum of the surface areas of the quartz parts at the upper and lower ends of the tube body equivalent, so that the damage of the quartz parts in the furnace tube can be reduced during PM, and the occurrence of thin silicon nitride film deposited on the surface of the wafer located at the upper end of the tube body when the silicon nitride film is deposited can be avoided, thereby improving the yield of the product.
[0037] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion. The various embodiments in this specification are described in a related manner, and the same and similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.
[0038] The above is only a preferred embodiment of the utility model, and is not intended to limit the protection scope of the utility model. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principle of the utility model, and these improvements and modifications should also be regarded as the protection scope of the utility model.
Claims
1. A LPCVD furnace tube structure, comprising a tube body, characterized in that: The tube body is provided with: A wafer boat, used for placing wafers, the wafer boat comprises a plurality of slots stacked along a first direction, each of the slots can hold a wafer, and the first direction is perpendicular to the bottom surface of the tube body; A first heat preservation barrel connected to the bottom of the wafer boat, wherein the first heat preservation barrel is provided with a plurality of first support layers stacked along the first direction, and a first heat preservation sheet can be placed on each of the first support layers; The second insulation barrel is connected to the top of the wafer boat. The second insulation barrel is provided with a plurality of second support layers stacked along the first direction. A second insulation sheet can be placed on one of the second support layers. The same second support layer can be provided with second insulation sheets with different surface roughnesses.
2. The LPCVD furnace tube structure according to claim 1, characterized in that: The inner wall of the tube is made of quartz.
3. The LPCVD furnace tube structure according to claim 1, characterized in that: The tube body is cylindrical.
4. The LPCVD furnace tube structure according to claim 1, characterized in that: The gas flow direction in the tube body is parallel to the bottom surface of the tube body, and the gas flow rates at the top and bottom of the tube body are the same.
5. The LPCVD furnace tube structure according to claim 1, characterized in that: The surface of the second heat-insulating sheet facing the top of the tube body is a rough surface.
6. The LPCVD furnace tube structure according to claim 5, characterized in that: The second thermal insulation sheet has a plurality of different specifications, and the surface roughness of the second thermal insulation sheet of different specifications is different.
7. The LPCVD furnace tube structure according to claim 5, characterized in that: The roughness of the rough surface of the second heat-insulating sheet is selected to be opposite to the roughness of the inner wall material of the tube body.
8. The LPCVD furnace tube structure according to claim 1, characterized in that: The first heat-insulating barrel has the same structure as the second heat-insulating barrel.
9. The LPCVD furnace tube structure according to claim 1, characterized in that: The distance between adjacent second supporting layers is adjustable.
10. The LPCVD furnace tube structure according to claim 1, characterized in that: The material of the second thermal insulation sheet is quartz.