A quartz boat device for placing a silicon wafer
By creating circular through-holes on the quartz boat teeth and adopting an equilateral triangular structure, the problem of uneven local gas deposition on silicon wafers was solved, achieving uniform gas diffusion and improved battery performance during high-temperature processes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHUZHOU JIETAI NEW ENERGY TECH CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-06-16
AI Technical Summary
The existing quartz boat tooth design causes the local gas deposition rate of silicon wafers to be too slow in the high-temperature doping process, resulting in thickness and doping concentration differences, which affect the appearance and electrical performance of the battery.
Circular through holes are made on the quartz boat teeth, and an equilateral triangular structure is adopted. The gas diffusion uniformity is improved and stress concentration is reduced by the evenly distributed small holes.
This technology achieves uniform gas diffusion in silicon wafers during high-temperature processes, eliminates tooth-mark defects, and improves the appearance and electrical performance of the battery.
Smart Images
Figure CN122227902A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photovoltaic manufacturing technology, specifically relating to a quartz boat device for placing silicon wafers. Background Technology
[0002] In the production of crystalline silicon solar cells, the key to forming the pn junction lies in the high-temperature doping process. This process typically uses a quartz boat and its toothed structure as a support for the silicon wafer. The silicon wafer is placed in a high-temperature furnace tube, exposing it to doping source gases such as boron, phosphorus, and oxygen. Impurities are incorporated through a diffusion process, thereby forming the pn junction.
[0003] In the source diffusion process of crystalline silicon solar cells, the process temperature is typically high, generally reaching 600-900℃ or even higher. Quartz boats possess excellent high-temperature stability, maintaining structural and performance stability under such high temperatures without significant deformation or softening, thus reliably supporting the silicon wafer to complete the process. Therefore, they are irreplaceable under current technological conditions. The specific operation involves inserting the silicon wafer into the quartz boat automatically or manually, positioning it using fixed quartz boat teeth, and then pushing the boat into a vacuum high-temperature deposition chamber. However, in existing quartz boat tooth designs, during vacuum high-temperature deposition, the solid surface of the boat teeth prevents gas flow in the contact area with the silicon wafer, resulting in slow local source deposition rates and low doping levels or thicknesses. Meanwhile, gas flow is smooth in the non-boat tooth areas of the silicon wafer, leading to normal source deposition rates. This creates a significant thickness difference and doping concentration difference between the boat tooth area and other areas of the silicon wafer. The difference in source deposition thickness causes color variations in the boat print, and the difference in doping concentration results in insufficient contact in that area, causing poor electrochemical performance (EL). This not only affects the appearance of the cell but also its EL performance.
[0004] CN222106632U discloses a quartz boat, including a frame assembly and end plates. The frame assembly extends along a first direction, and two end plates are connected to the two ends of the frame assembly opposite each other along the first direction. At least one end plate is provided with a first flow channel, which extends through the end plate along the first direction. A gas guiding structure is provided within the first flow channel, dividing the first flow channel into multiple flow holes. The end plates achieve uniformity of process gas flow on the silicon wafer surface within the quartz boat. However, the teeth of the quartz boat are rigid and non-porous contacts. When the tooth grooves contact the silicon wafer, local stress is easily generated, leading to uneven deposition of diffusion source gas and forming tooth imprint defects. Summary of the Invention
[0005] The purpose of this invention is to provide a quartz boat device for placing silicon wafers, thereby solving the aforementioned technical problems existing in the prior art.
[0006] Therefore, the technical solution provided by the present invention is as follows:
[0007] A quartz boat device for placing silicon wafers includes a frame and a plurality of quartz boat teeth, the quartz boat teeth being arranged parallel and equidistantly on the frame, with a tooth groove between two adjacent quartz boat teeth, and a circular through hole opened on the quartz boat teeth.
[0008] This invention achieves hollowing out of the contact area through circular through holes, thereby improving the uniformity of gas diffusion, reducing stress concentration, and eliminating tooth mark defects.
[0009] Furthermore, the longitudinal section of the quartz boat tooth is an equilateral triangle.
[0010] First, equilateral triangles possess geometric symmetry and high structural stability. When a silicon wafer is placed, under the influence of gravity, its edges naturally slide towards the center of the valley of the triangular quartz teeth. This self-centering effect ensures that the radial position of the silicon wafer is consistent on each quartz tooth, guaranteeing uniform heating and central positioning of the wafer during the deposition process. Furthermore, the equilateral triangular teeth passively lock the silicon wafer in its designed standard position, improving process repeatability.
[0011] Secondly, since the edges of silicon wafers are typically rounded, when the wafer is placed, it is actually tangent to the hypotenuse of an equilateral triangle formed by the quartz boat teeth, and contacts the angle formed by the two sides of the triangle, thus forming an extremely narrow surface contact or a near-perfect line contact. The extremely narrow contact surface of the equilateral triangle minimizes the heat conduction path, making the temperature of the silicon wafer support point as close as possible to the temperature of the silicon wafer body, thereby ensuring the uniformity of the process.
[0012] Finally, in the vapor deposition process, the reactive gases need to flow beneath the silicon wafer. The open angle of the equilateral triangle is more conducive to gas passage than other shapes of deep grooves (such as conventional rectangular grooves), reducing airflow dead zones. At the same time, the upward-pointing structure of the triangle's apex makes it less likely for byproduct dust generated during the process to accumulate on the groove surface, instead causing it to slide to the bottom or edges, thus extending the service life of the quartz boat or support frame before contamination exceeds the limit.
[0013] Furthermore, the circular through hole is the inscribed circle of an equilateral triangle.
[0014] In some specific implementations, the area of the inscribed circle is between 50% and 80% of the surface area of the quartz boat attached to the silicon wafer.
[0015] Furthermore, the circular through hole consists of multiple small circles of equal size that are evenly distributed, and the multiple small circles are not tangent to each other and the number is not less than four.
[0016] The uniformly distributed micropores achieve the dual functions of gas diffusion and stress dispersion.
[0017] Furthermore, the radius of the circular through hole is less than one-third of the height of the quartz boat tooth.
[0018] Furthermore, when there are four circular through holes, their radius is less than one-sixth of the height of the quartz boat tooth.
[0019] Furthermore, the spacing of the tooth grooves is 6 to 10 times the thickness of the silicon wafer, and the spacing between two adjacent quartz boat teeth is 3.78 to 6.3 mm.
[0020] The spacing between two adjacent quartz boat teeth can be narrowed from 10 times the thickness of the silicon wafer to between 6 and 10 times, which increases the bonding ability and reduces the fluctuation of the silicon wafer under gas disturbance at high temperature.
[0021] Furthermore, the thickness of the quartz boat teeth is 3~5mm.
[0022] Furthermore, the height of the quartz boat teeth is 8~12mm.
[0023] Furthermore, the side length of the quartz boat tooth is 9.24~13.86mm.
[0024] The beneficial effects of this invention are as follows:
[0025] This invention addresses the issue of gas flow defects caused by creating one large hole or multiple evenly distributed small holes in the area where the quartz boat teeth adhere to the silicon wafer. This ensures sufficient support at the tooth points while allowing for adequate gas flow within the wafer attachment area. Under specific quartz boat carrier conditions and high-temperature, low-pressure processes, this results in sufficient gas circulation in the quartz boat tooth contact area and consistent source deposition uniformity with other areas. This fundamentally solves the problems of surface marks and EL defects caused by current quartz boat carriers. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the structure of the first embodiment of the present invention;
[0027] Figure 2 This is a schematic diagram of the structure of the second embodiment of the present invention;
[0028] Figure 3 This is a schematic diagram of the structure of the third embodiment of the present invention;
[0029] Figure 4 This is a schematic diagram of the fourth embodiment of the present invention;
[0030] Figure 5 This is a side view of a quartz boat tooth.
[0031] Explanation of reference numerals in the attached diagram: 1. Quartz boat tooth; 2. Circular through hole. Detailed Implementation
[0032] The following specific embodiments illustrate the implementation of the invention. Those skilled in the art can easily understand other advantages and effects of the invention from the content disclosed in this specification.
[0033] Exemplary embodiments of the invention are now described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention.
[0034] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.
[0035] Example 1
[0036] This embodiment provides a quartz boat device for placing silicon wafers, including a frame and a plurality of quartz boat teeth 1. The quartz boat teeth 1 are arranged parallel and equidistantly on the frame, and there is a tooth groove between two adjacent quartz boat teeth 1. A circular through hole 2 is opened on the quartz boat teeth 1.
[0037] Taking the longitudinal section of a quartz boat tooth in existing technology as an example, which is an isosceles triangle, a circular through hole is opened at any position on it. For example... Figure 1 As shown.
[0038] Quartz boats are generally made of high-purity quartz glass. Quartz glass is primarily composed of silicon dioxide (SiO2), and its purity is typically required to be above 99.99%. High-purity raw materials prevent the introduction of impurities during high-temperature processing, thus preventing contamination of the silicon wafers and ensuring the performance of crystalline silicon solar cells. It possesses the following characteristics:
[0039] High Temperature Resistance: In the source diffusion process of crystalline silicon solar cells, the process temperature is usually high, typically reaching 600~900℃ or even higher. Quartz boats have excellent high-temperature stability, maintaining structural and performance stability in such high-temperature environments without significant deformation or softening, thus reliably supporting the silicon wafer to complete the process.
[0040] Chemical stability: Various source gases and other chemical substances are used in the source diffusion process. Quartz boats possess excellent chemical stability, exhibiting inertness to most chemical reagents and being unlikely to react chemically with the gases used in the process. This prevents the quartz boat from interacting with the process gases and generating impurities that could affect the diffusion effect on the silicon wafer and the performance of the battery.
[0041] Low coefficient of thermal expansion: Quartz materials have a low coefficient of thermal expansion, resulting in minimal dimensional changes in the quartz boat when the temperature changes. During the heating and cooling processes of the source expansion process, this characteristic reduces damage to the quartz boat itself and the silicon wafer it supports due to thermal stress, ensuring the flatness of the silicon wafer and the uniformity of the process.
[0042] Light transmittance (partial characteristic): Although quartz boats are mainly used for carrying loads, their certain light transmittance can facilitate the observation and detection of the silicon wafer's condition in some process monitoring or optical inspection stages, helping to identify problems in the process in a timely manner.
[0043] Electrical insulation: In the battery manufacturing process, there may be various electric fields or currents. The good electrical insulation of the quartz boat can prevent the current from interfering with the process and ensure the stability and consistency of the process.
[0044] This invention utilizes circular through-holes in the quartz boat teeth to hollow out the contact area. Thus, even at high temperatures, the quartz boat teeth, acting as a positioning carrier for the silicon wafer, allow process gases to pass through the contact area evenly, improving gas diffusion uniformity and achieving optimal process results. This eliminates appearance and process differences between the contact area between the quartz boat teeth and the silicon wafer and other non-contact areas. Simultaneously, the circular through-holes release stress, reduce stress concentration, and prevent the quartz boat teeth from scratching the silicon wafer, eliminating tooth marks and preventing process defects such as quartz boat teeth defects.
[0045] Example 2
[0046] Based on Example 1, this example provides a quartz boat device for placing silicon wafers, wherein the longitudinal section of the quartz boat teeth 1 is an equilateral triangle.
[0047] In this context, the longitudinal section of the quartz boat tooth 1 refers to the surface that contacts the silicon wafer. For example... Figure 5 As shown, these are the faces of two adjacent quartz boat teeth facing each other, with a tooth groove between them.
[0048] Compared to the isosceles triangular, rectangular, or trapezoidal toothed grooves in existing technologies, the quartz boat teeth with an equilateral triangular longitudinal section minimize the heat conduction path through geometric "point / line contact," preventing heat from rapidly escaping through the contact points and causing the silicon wafer contact point temperature to be lower than the surrounding area, forming "cold spots" and affecting film thickness uniformity. The equilateral triangular longitudinal section solves the three major pain points in silicon wafer manufacturing: cleanliness, temperature uniformity, and positioning accuracy, making it suitable for the diffusion of sources such as boron, oxygen, and phosphorus in crystalline silicon solar cells.
[0049] Example 3
[0050] Based on Example 2, this example provides a quartz boat device for placing silicon wafers, wherein the circular through hole 2 is the inscribed circle of an equilateral triangle.
[0051] like Figure 2 As shown, the longitudinal section (the surface in contact with the silicon wafer) of the quartz boat tooth 1 is an equilateral triangle, the circular through hole is a single inscribed circle, the radius of the circular through hole 2 is less than one-third of the height of the quartz boat tooth 1, and the other non-hole areas of the quartz boat tooth 1 are continuous, maintaining the supporting force on the silicon wafer.
[0052] like Figure 2 As shown, the side length 'a' of the quartz boat tooth 1 is 9.24~13.86 mm. (As...) Figure 5 As shown, the slot spacing d between the quartz boat teeth 1 is 6 to 10 times the thickness of the silicon wafer, specifically 0.78 to 1.3 mm, and the tooth spacing c is 3.78 to 6.3 mm; the thickness of the quartz boat teeth 1 is 3 to 5 mm; and the height e (i.e., the height of the equilateral triangle) of the quartz boat teeth 1 is 8 to 12 mm.
[0053] Specifically, the area of the inscribed circle is between 50% and 80% of the surface area where the quartz boat and the silicon wafer are attached.
[0054] Compared with the prior art, in this embodiment, the spacing between two adjacent quartz boat teeth 1 is narrowed from 10 times the thickness of the silicon wafer to between 6 and 10 times, which increases the bonding ability and reduces the fluctuation of the silicon wafer under gas disturbance at high temperature.
[0055] Example 4
[0056] Based on Embodiment 2, this embodiment provides a quartz boat device for placing silicon wafers, wherein the circular through hole 2 is a plurality of small circles of equal size evenly distributed, the plurality of small circles are not tangent and the number is not less than four.
[0057] In this embodiment, as Figure 3 As shown, the circular through-hole 2 of the quartz boat tooth 1 consists of four small circles of equal size that are not tangent to each other. The radius of the circular hole is less than one-sixth of the height of the quartz boat tooth 1. The other non-hole areas of the quartz boat tooth 1 are continuous, maintaining the supporting force on the silicon wafer.
[0058] Among them, the side length a of the quartz boat tooth 1 is 9.24~13.86mm, the groove spacing d between the quartz boat teeth 1 is 6~10 times the thickness of the silicon wafer, specifically 0.78~1.3mm, the tooth spacing c is 3.78~6.3mm, the thickness of the quartz boat tooth 1 is 3~5mm, and the height e of the quartz boat tooth is 8~12mm.
[0059] Example 5
[0060] Based on Example 2, this example provides a quartz boat device for placing silicon wafers, such as... Figure 4As shown, the circular through-holes 2 consist of five or more small circles of equal size, which are not tangent to each other and are evenly distributed on the contact surface of the quartz boat teeth 2. The other non-hole areas of the quartz boat teeth 1 are continuous, maintaining the supporting force on the silicon wafer.
[0061] The quartz boat teeth 1 have a side length a of 9.24~13.86mm, a slot spacing d between the quartz boat teeth 1 of 6~10 times the silicon wafer thickness, specifically 0.78~1.3mm, and a tooth spacing c of 3.78~6.3mm; the thickness of the quartz boat teeth 1 is 3~5mm, and the height e of the quartz boat teeth is 8~12mm. The radius R3 of the circular hole is 0.1~0.25 of the side length a.
[0062] The uniformly distributed micropores achieve a dual function of gas diffusion and stress dispersion: each micropore acts as a tiny flow resistance; when gas passes through a large number of parallel micropores, the pressure drop across the entire quartz spar is uniform, thus ensuring a consistent gas flow rate through each micropore. When the silicon wafer expands due to heat, it can slide slightly over the micropores, and the edges of the micropores provide tiny deformation space, avoiding the enormous shear stress inherent in continuous surfaces.
[0063] This embodiment ensures uniform silicon wafer surface temperature through uniform micropore distribution, thereby achieving uniform thermal stress, uniform diffusion source gas deposition, and eliminating tooth mark defects.
[0064] Comparative Example 1
[0065] Compared with Comparative Example 1, Example 3 differs in that there is no inscribed circular through hole, while all other parameters are the same.
[0066] Comparative Example 2
[0067] Compared with Comparative Example 2 and Example 4, the difference is that the longitudinal section of the quartz boat tooth is an isosceles trapezoid, the upper base is half the length of the lower base, and the length of the lower base is 9.24~13.86mm. All other parameters are the same.
[0068] Comparative Example 3
[0069] Compared with Comparative Example 3, the difference is that the circular through holes are of different sizes and randomly distributed, while other parameters are the same.
[0070] Comparative Example 4
[0071] Compared with Example 3, Comparative Example 4 differs in that the inscribed circular through-hole is changed to an inscribed square through-hole.
[0072] Phosphorus diffusion was performed on 1000 silicon wafers using quartz boats from Examples 1, 3-5, and Comparative Examples 1-4 (temperature 600-900℃, time 80-110 min, diffusion source gas flow rate 100-1500 sccm). After diffusion, the uniformity of PSG (phosphosilicate glass) thickness, sheet resistance, appearance defects, and el defects of the quartz boat teeth in the quartz boat tooth area of the silicon wafers were evaluated. The results are shown in Table 1.
[0073] Table 1
[0074] Regional PSG (phosphosilicate glass) thickness uniformity Sheet resistance uniformity Quartz boat teeth appearance defect rate Quartz boat tooth defect rate Example 1 2.45% 3.65% 0.00% 0.5% Example 3 2.3% 3.5% 0.00% 0.00% Example 4 2.25% 3.3% 0.00% 0.00% Example 5 2.2% 3.1% 0.00% 0.00% Comparative Example 1 5% 7% 2% 3% Comparative Example 2 4% 6% 1% 2% Comparative Example 3 3% 5% 0.00% 1% Comparative Example 4 2.43% 3.67% 0.00% 0.4%
[0075] As shown in Table 1, the uniformity of Example 3 is better than that of Example 1. This is because the longitudinal section of the quartz boat tooth 1 in Example 1 adopts an isosceles triangle of the prior art, which results in inconsistent contact surfaces between the silicon wafer and the three sides, with the apex angle deviating by 60 degrees. When the airflow bypasses the tooth shape, it is easier to generate tiny eddies or turbulence at the tooth root or wafer edge. These eddies can lead to uneven local reactant concentrations, thereby affecting the uniformity of film thickness. In contrast, the equilateral triangle of Example 3 is not only the most stable and compact in geometry, but also provides a very sharp and stable support point, which can minimize the contact area between the back of the silicon wafer and the quartz, resulting in more uniform deposition.
[0076] Comparing Example 3 and Comparative Example 1, it can be seen that the via configuration improves the uniformity of deposition. In Examples 3 to 5, the uniformity of PSG thickness and sheet resistance gradually decreases (the smaller the value, the more uniform the thickness in each region). This indicates that with uniform via distribution, as the number of vias increases, the gas flow in the quartz boat tooth contact area is sufficient, and the uniformity of source deposition is improved. Compared with Comparative Example 2, Example 4 uses equilateral triangular quartz boat teeth 1, which minimizes the heat conduction path and avoids rapid heat loss through the contact point, resulting in the silicon wafer contact point temperature being lower than the surrounding area, forming "cold spots" and affecting the film thickness uniformity. Therefore, the deposition effect of Example 4 is better than that of Comparative Example 2. Compared with Comparative Example 3 and Example 5, the vias are of unequal size and randomly distributed, which easily leads to turbulent airflow, causing local differences in film deposition rate and reducing film uniformity.
[0077] As can be seen from the comparison between Example 3 and Comparative Example 4, Comparative Example 4 has poor uniformity. This is because although the square through-holes allow airflow to pass through, the right angles are stress concentration points, and when the airflow passes through the straight edges and right angles, obvious vortex or stagnant zones are easily formed on the leeward side. This leads to uneven distribution of reactant concentration around the holes, resulting in thickness deviations or compositional inhomogeneities in the deposited film near the holes.
[0078] The examples above are merely illustrative of the invention and do not constitute a limitation on the scope of protection of the invention. Any design that is the same as or similar to the invention falls within the scope of protection of the invention.
Claims
1. A quartz boat device for placing silicon wafers, characterized in that: It includes a frame and multiple quartz boat teeth, which are arranged parallel and equidistantly on the frame. There is a tooth groove between two adjacent quartz boat teeth, and a circular through hole is opened on each quartz boat tooth.
2. The quartz boat device for placing silicon wafers according to claim 1, characterized in that: The longitudinal section of the quartz boat tooth is an equilateral triangle.
3. The quartz boat device for placing silicon wafers according to claim 2, characterized in that: The circular through hole is the inscribed circle of an equilateral triangle.
4. The quartz boat device for placing silicon wafers according to claim 2, characterized in that: The circular through-hole consists of multiple small circles of equal size that are evenly distributed, and the number of these small circles is not less than four and they are not tangent to each other.
5. The quartz boat device for placing silicon wafers according to claim 3, characterized in that: The radius of the circular through hole is less than one-third of the height of the quartz boat tooth.
6. The quartz boat device for placing silicon wafers according to claim 4, characterized in that: When there are four circular through holes, their radius is less than one-sixth of the height of the quartz boat tooth.
7. A quartz boat device for placing silicon wafers according to any one of claims 1-6, characterized in that: The spacing between the tooth grooves is 6 to 10 times the thickness of the silicon wafer, and the spacing between two adjacent quartz boat teeth is 3.78 to 6.3 mm.
8. A quartz boat device for placing silicon wafers according to any one of claims 1-6, characterized in that: The thickness of the quartz boat teeth is 3~5mm.
9. A quartz boat device for placing silicon wafers according to any one of claims 1-6, characterized in that: The height of the quartz boat teeth is 8~12mm.
10. A quartz boat device for placing silicon wafers according to any one of claims 1-6, characterized in that: The side length of the quartz boat tooth is 9.24~13.86mm.