Quartz boat
Patent Information
- Application Number
- CN202420031995.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-05
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2034-01-05
AI Technical Summary
The existing quartz boats used in LPCVD for preparing tunnel passivation structures in solar cells result in wrap-around deposition of polysilicon and phosphorus on the front side of silicon wafers, leading to the formation of borophosphorus glass, which complicates cleaning and can damage the PN junction, affecting battery performance.
A quartz boat design with intermediate clamping strips between adjacent clamping strips to increase the gap between silicon wafers, ensuring a wider intrinsic polysilicon layer covers the edges, preventing phosphorus diffusion into borosilicate glass and eliminating the need for additional cleaning steps.
Prevents the formation of borophosphorus glass, simplifies the cleaning process, and maintains the photoelectric conversion efficiency and yield rate of the solar cells by ensuring stable wafer fixation and preventing phosphorus diffusion.
Smart Images
Figure CN222190656U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of solar cell manufacturing, and in particular relates to a quartz boat. Background Art
[0002] During the preparation of Topcon cells (also known as tunneling oxide passivated contact cells), an ultra-thin tunneling silicon oxide layer and a highly doped polysilicon thin layer are prepared on the back of the cell, and the two together form a passivated contact structure. Currently, one of the commonly used methods for preparing highly doped polysilicon thin layers is LPCVD (Low Pressure Chemical Vapor Deposition). During the preparation process, a layer of intrinsic polysilicon layer needs to be prepared on the surface of the silicon wafer first, and then phosphorus atoms are doped into the intrinsic polysilicon layer through a phosphorus diffusion process to obtain a highly doped polysilicon film layer.
[0003] The wafer carrier used in the preparation of the tunnel passivation structure by this method is a quartz boat. There are card points at both ends of the overlapping silicon wafers to fix the silicon wafers. During the preparation of the tunnel passivation structure, since the adjacent silicon wafers cannot be completely fitted together, there is a small gap between the silicon wafers. The reaction gas will spontaneously diffuse to the gap on the front side of the silicon wafer and produce a small area of wrap-coating layer. Under high temperature conditions, the reaction gas is activated and deposited on the front side of the silicon wafer to produce wrap-coating (such as Figure 4 and Figure 5 As shown in the figure, when doped polysilicon is deposited using LPCVD equipment, polysilicon and phosphorus atoms bypass the back and edge of the silicon wafer and are deposited on the front of the silicon wafer.
[0004] In order to remove the influence of wrap-around plating on battery performance, it is necessary to add an additional cleaning step after doped polysilicon deposition to remove the wrap-around plating. If the wrap-around plating structure contains a corroded borophosphorus glass layer, the borophosphorus glass will be quickly etched in the same etching solution, which may cause damage to the PN junction during the cleaning process, affecting the photoelectric conversion efficiency of the battery and the battery yield. Utility Model Content
[0005] The embodiment of the utility model provides a quartz boat, which aims to avoid the generation of borophosphorus glass on the front side, improve the conversion efficiency of the battery, and reduce the difficulty of cleaning.
[0006] To achieve the above-mentioned purpose, the technical solution adopted by the utility model is: to provide a quartz boat, including: a quartz boat body, a plurality of clamping strips are arranged in the quartz boat body, and a clamping groove for clamping two silicon wafers placed back to back is formed between two adjacent clamping strips; wherein, an intermediate clamping strip is also arranged between two adjacent clamping strips, and the intermediate clamping strip is located between the two silicon wafers placed back to back.
[0007] In one achievable manner, the height of the middle clip strip is smaller than the height of the fixing strip.
[0008] In an achievable manner, the height h2 of the middle clamping strip is less than the height h1 of the fixing strip, and the range of h2 is 1 / 2h1-2 / 3 h1, with the unit of mm.
[0009] In one achievable manner, the thickness of the middle clip strip is smaller than the thickness of the fixing strip.
[0010] In one achievable manner, the thickness m2 of the middle clip is 0.1 mm-0.3 mm.
[0011] In a feasible manner, the fixing strips and the middle fixing strips are alternately formed into a comb-teeth shape, and the cross-sectional shape of the middle fixing strips is consistent with the cross-sectional shape of the fixing strips.
[0012] In one achievable manner, the upper end of the cross-sectional shape of the middle clip is a curve corresponding to the major axis of the ellipse.
[0013] In one achievable manner, the upper end of the cross-sectional shape of the middle clip strip is a trapezoidal structure.
[0014] Compared with the prior art, the quartz boat provided by the utility model has the following beneficial effects: on the original quartz boat, without changing the number of silicon wafer carriers and the spacing between adjacent clamping strips, the width of the original clamping strip is reduced, the gap between two adjacent clamping strips is increased, the remaining space is used to add an intermediate clamping strip between the two adjacent clamping strips, and the intermediate clamping strip is used to separate two silicon wafers back to back, so that the gap between the two adjacent clamping strips is increased as a whole, and the intermediate clamping strip cooperates with the clamping strip to fix the silicon wafer, so that the gap between adjacent silicon wafers is increased as a whole, and a wider intrinsic polysilicon layer is obtained to cover the edge of BSG (Borosilicate Glass) borosilicate glass, and the width of phosphorus diffusion cannot exceed the width of intrinsic polysilicon, so that phosphorus is prevented from diffusing into BSG to form BPSG, simplifying the cleaning process, avoiding the problem of damaging the PN junction during cleaning, and ensuring the photoelectric conversion efficiency of the battery and the yield rate of the battery.
[0015] The quartz boat provided by the utility model increases the gap between silicon wafers by changing the quartz boat structure during polysilicon deposition, adding extra card points between adjacent card points, and increasing the width of intrinsic polysilicon plated around the front side of the silicon wafer, thereby preventing phosphorus from diffusing into BSG to form BPSG. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A schematic diagram of the structure of a quartz boat provided in an embodiment of the utility model;
[0017] Figure 2A schematic diagram of a partially enlarged structure of a quartz boat provided in an embodiment of the utility model;
[0018] Figure 3 A schematic diagram showing a comparison of the structures of the quartz boat provided in the background art (Fig. a) and the quartz boat provided in the present invention (Fig. b) for plating the silicon wafer on the front side;
[0019] Figure 4 The schematic diagram of the structure of the quartz boat plating process (arrows represent phosphorus diffusion gas);
[0020] Figure 5 A schematic diagram of the structure of a quartz boat provided as background technology;
[0021] Description of reference numerals:
[0022] 1. Silicon wafer; 2. Middle clip bar; 3. Fixing bar; 4. Phosphorus diffusion; 5. Intrinsic polysilicon; 6. Borophosphorus glass; 7. Borosilicate glass. DETAILED DESCRIPTION
[0023] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0024] Please also read Figure 1 and Figure 2 The quartz boat provided by the utility model is now described. The quartz boat comprises a quartz boat body, in which a plurality of clamping strips 3 are arranged, and a clamping groove for clamping two silicon wafers 1 placed back to back is formed between two adjacent clamping strips 3; wherein an intermediate clamping strip 2 is further arranged between two adjacent clamping strips 3, and the intermediate clamping strip 2 is located between the two silicon wafers 1 placed back to back.
[0025] The quartz boat provided by the utility model increases the gap between silicon wafers 1 by changing the structure of the quartz boat during polysilicon deposition, and increases the width of the intrinsic polysilicon 5 plated around the front side of the silicon wafer 1, thereby preventing phosphorus from diffusing 4 into BSG (abbreviation of Borosilicate Glass, borosilicate glass 7) to form borophosphorus glass 6.
[0026] Compared with the prior art, the quartz boat provided by the utility model has the following beneficial effects: on the original quartz boat, without changing the number of silicon wafers 1 carried and the spacing between adjacent clamping strips 3, the width of the original clamping strip 3 is reduced, the gap between two adjacent clamping strips 3 is increased, and the remaining space is used to add an intermediate clamping strip 2 between the two adjacent clamping strips 3, and the intermediate clamping strip 2 is used to separate the two back-to-back silicon wafers 1, so that the gap between the two adjacent clamping strips 3 is increased as a whole, and then the intermediate clamping strip 2 cooperates with the clamping strip 3 to fix the silicon wafer 1, so that the gap between adjacent silicon wafers 1 is increased as a whole, and a wider intrinsic polysilicon 5 layer is obtained to cover the edge of the BSG borosilicate glass 7, and the width of the phosphorus diffusion 4 cannot exceed the width of the intrinsic polysilicon 5, so as to prevent the phosphorus diffusion 4 from entering the borosilicate glass 7 to form borophosphorus glass 6, and there is no need to clean the borophosphorus glass 6, thereby avoiding the problem of damaging the PN junction during cleaning, and ensuring the photoelectric conversion efficiency of the battery and the yield rate of the battery.
[0027] For example, Figure 1 , Figure 2 and Figure 5 As shown, the number of the original quartz boat's clamping slots is 120, and the distance between the two clamping strips 3 is L (see Figure 5 ); In the present application, the number of the card slots is kept unchanged at 120 (such as Figure 1 As shown), the number of silicon wafers 1 is ensured to remain unchanged. When the spacing between the clamping strips 3 remains unchanged, the gap between two adjacent clamping strips 3 is enlarged by reducing the thickness of the clamping strips 3, thereby increasing the gap between the back-to-back silicon wafers 1. The increase in the gap will make the fixation of the silicon wafer 1 unstable. Therefore, an intermediate clamping strip 2 is provided between the two silicon wafers 1 to ensure the firmness of the clamping of the silicon wafer 1 and avoid the problem of the silicon wafer 1 tilting.
[0028] like Figure 3 As shown, the width of the intrinsic polysilicon 5 is w2, and the width w1 of the PSG (Phosphosilicate Glass) phosphorus diffusion 4 cannot exceed the width w2 of the intrinsic polysilicon 5 layer, so borophosphorus glass 6 cannot be formed on the front of the silicon wafer 1. After changing the quartz boat structure, the gap between the silicon wafers 1 increases when depositing the intrinsic polysilicon 5, and the width of the intrinsic polysilicon 5 to be plated increases, so that the width of the phosphorus diffusion 4 cannot cross the intrinsic polysilicon 5 to reach the borosilicate glass 7, avoiding the formation of borophosphorus glass 6 on the front of the silicon wafer 1. Therefore, no cleaning process is required, and the formation of borophosphorus glass 6, which is more difficult to clean, is avoided. Ultimately, the difficulty of the cleaning process of the plating is reduced, the problem of damaging the PN junction during cleaning is avoided, and the photoelectric conversion efficiency and the yield rate of the battery are guaranteed.
[0029] In some embodiments, Figure 1 and Figure 2As shown, the height of the middle clip strip 2 is smaller than the height of the fixing strip 3 .
[0030] In some embodiments, Figure 1 and Figure 2 As shown, the height h2 of the middle clamping strip 2 is less than the height h1 of the clamping strip 3, and the range of h2 is 1 / 2h1-2 / 3 h1, and the unit is mm.
[0031] In some embodiments, Figure 1 and Figure 2 As shown, the thickness of the middle clip strip 2 is smaller than the thickness of the fixing strip 3 .
[0032] In some embodiments, the thickness m2 of the middle clip 2 is 0.1 mm-0.3 mm.
[0033] In some embodiments, Figure 1 As shown, the clamping strips 3 and the middle clamping strips 2 alternately form a comb shape, and the cross-sectional shape of the middle clamping strips 2 is consistent with the cross-sectional shape of the clamping strips 3 .
[0034] Preferably, the fixing strips 3 and the middle fixing strips 2 are alternately formed into a comb shape, and the height of the middle fixing strips 2 is smaller than the height of the fixing strips 3 .
[0035] In some embodiments, Figure 1 As shown, the upper end of the cross-sectional shape of the middle clamping strip 2 is a curve corresponding to the long axis of the ellipse. Specifically, the cross-sectional shapes of the middle clamping strip 2 and the clamping strip 3 are both rectangular, and the upper ends are made into an elliptical curve. On the one hand, this flat curve reduces the space occupied horizontally, and on the other hand, the thickness of the elliptical cross-sectional curve gradually decreases from bottom to top, which has a guiding effect on the silicon wafer 1 and facilitates the insertion of the silicon wafer 1.
[0036] In some embodiments, the upper end of the cross-sectional shape of the middle clip 2 is a trapezoidal structure (not shown). Similarly, the trapezoidal shape of the upper end of the middle clip 2 and the clamping strip 3 has a guiding effect on the silicon wafer 1, so that the upper end of the clamping groove forms a bell mouth, which is convenient for the silicon wafer 1 to be inserted.
[0037] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A quartz boat, characterized in that: include: A quartz boat body, wherein a plurality of clamping strips (3) are arranged in the quartz boat body, and a clamping groove for clamping two silicon wafers (1) placed back to back is formed between two adjacent clamping strips (3); wherein an intermediate clamping strip (2) is also arranged between two adjacent clamping strips (3), and the intermediate clamping strip (2) is located between the two silicon wafers (1) placed back to back.
2. The quartz boat according to claim 1, characterized in that: The height of the middle clamping strip (2) is smaller than the height of the clamping strip (3).
3. The quartz boat according to claim 2, characterized in that: The height h2 of the middle clamping strip (2) is smaller than the height h1 of the clamping strip (3), and the range of h2 is 1 / 2h1-2 / 3 h1, with the unit being mm.
4. The quartz boat according to claim 1, characterized in that: The thickness of the middle clamping strip (2) is smaller than the thickness of the fixing strip (3).
5. The quartz boat according to claim 4, characterized in that: The thickness m2 of the middle clip (2) is 0.1 mm-0.3 mm.
6. The quartz boat according to claim 1, characterized in that: The fixing strips (3) and the intermediate fixing strips (2) are alternately formed into a comb-teeth shape, and the cross-sectional shape of the intermediate fixing strips (2) is consistent with the cross-sectional shape of the fixing strips (3).
7. The quartz boat according to claim 6, characterized in that: The upper end of the cross-sectional shape of the middle clamping strip (2) is a curve corresponding to the major axis of the ellipse.
8. The quartz boat according to claim 6, characterized in that: The upper end of the cross-sectional shape of the middle clamping strip (2) is a trapezoidal structure.