A boat-supported flow equalizer to improve the uniformity of polysilicon

Abstract

This utility model relates to the field of solar cell manufacturing technology, and in particular to a flow equalization plate for improving the uniformity of polysilicon deposition. The plate includes a flow equalization plate, a flow guide plate, and an installation mechanism. The surface of the flow equalization plate has flow equalization holes for improving the flow rate of the reactant gas. A flow guide plate is located behind the flow equalization plate to guide the reactant gas through it. Installation mechanisms for mounting at the front end of the furnace opening boat are located on both sides of the flow equalization plate and the flow guide plate. This utility model achieves effective dispersion of silane gas through the flow equalization plate and flow equalization holes, avoiding concentrated gas impact and resulting in more uniform polysilicon deposition. This solves the problem of poor polysilicon uniformity at the furnace opening in traditional processes.

Description

Technical Field

[0001] This utility model relates to the field of solar cell manufacturing technology, and in particular to a slab current equalization plate for improving the uniformity of POLY silicon. Background Technology

[0002] Polycrystalline silicon is made by depositing an amorphous silicon layer on an ultrathin tunneling oxide layer to increase the electron migration rate and suppress the hole migration rate. In addition, polycrystalline silicon acts as an electron transport bridge in contact with metal. Therefore, the uniformity of polycrystalline silicon has a direct impact on the passivation performance of the back side of the solar cell.

[0003] Traditional low-pressure chemical vapor deposition processes typically employ a three-way gas inlet system: the furnace opening, the furnace interior, and the furnace tail. When the gas flow enters the tube from the inlet outlet, silicon wafers closer to the outlet receive a larger amount of gas, while those farther away receive less. In actual mass production, the silane from the furnace opening directly impacts the first reaction boat at the furnace opening. Excessive reactive gas directly contacts the first small boat, leading to excessively thick polysilicon in certain areas and ultimately resulting in poor polysilicon uniformity at the furnace opening.

[0004] Therefore, in response to the problem that the traditional low-pressure chemical vapor deposition process can easily lead to excessive local polysilicon thickness, resulting in poor polysilicon uniformity at the furnace mouth, a flow equalization plate for the boat support can be designed to improve the uniformity of polysilicon. By adding this flow equalization plate that can disperse silane gas at the front end of the boat support at the furnace mouth, the silane gas can no longer be concentrated in one position and impact, thereby effectively improving the uniformity of polysilicon at the furnace mouth. Utility Model Content

[0005] To overcome the shortcomings of traditional low-pressure chemical vapor deposition processes, which easily lead to excessive local polysilicon thickness and ultimately poor polysilicon uniformity at the furnace opening, this invention provides a boat support flow equalization plate to improve the uniformity of POLY silicon.

[0006] The technical solution is as follows: A flow equalization plate for improving the uniformity of POLY silicon includes a flow equalization plate, a flow guide plate and an installation mechanism; the surface of the flow equalization plate is provided with flow equalization holes for improving the flow rate of the reaction gas, and a flow guide plate is provided behind the flow equalization plate for guiding the reaction gas through the flow equalization plate. Both sides of the flow equalization plate and the flow guide plate are provided with an installation mechanism for mounting at the front end of the furnace mouth boat.

[0007] Furthermore, multiple sets of flow equalization holes are provided, which are evenly distributed on the surface of the flow equalization plate and penetrate the flow equalization plate.

[0008] Furthermore, the surface of the guide plate is uniformly provided with multiple sets of guide holes corresponding to the flow equalization holes, and the rear edge of each set of guide holes is provided with a flow chamfer.

[0009] Furthermore, the rear end of the flow equalization plate is provided with two sets of splicing slots, which are evenly distributed on both sides of the rear end edge of the flow equalization plate.

[0010] Furthermore, the front end of the deflector is provided with two sets of splicing clips, which are symmetrically arranged along the two sides of the front end of the deflector. The splicing clips are matched and engaged with the splicing slots.

[0011] Furthermore, the flow equalization plate is provided with a first fixing strip on both sides, and the flow guide plate is provided with a second fixing strip corresponding to the first fixing strip on both sides.

[0012] Furthermore, the installation mechanism includes a fixing sleeve, and the inner side of the fixing sleeve has a fixing groove for accommodating the first fixing strip and the second fixing strip.

[0013] Furthermore, the rear edge of the fixed sleeve is provided with an extension strip, and the rear end of the extension strip is provided with an installation strip that fits the boat support. Multiple sets of installation screw holes are evenly opened on the surface of the installation strip.

[0014] The beneficial effect is that, compared with the traditional low-pressure chemical vapor deposition process, which is prone to local excessive polysilicon thickness and ultimately poor polysilicon uniformity at the furnace mouth, this application effectively disperses silane gas by using a flow equalization plate and flow equalization holes to avoid concentrated gas impact, making polysilicon deposition more uniform. This solves the problem of poor polysilicon uniformity at the furnace mouth in traditional processes. In terms of actual effect, it can significantly improve the uniformity of the first small boat from a high level, for example, from 17.41% to about 5.19%, greatly improving the passivation performance of the back of the cell. Through the fixing sleeve, extension strip and mounting strip of the mounting mechanism, the device is firmly connected to the boat support. This connection method not only ensures the stability of the device during operation, but also adapts to certain thermal expansion and contraction, reducing the impact of displacement and other issues on the flow equalization effect. Through the flow guide holes and flow guide chamfer design on the flow guide plate, the gas is guided to flow in an orderly manner, reducing resistance and allowing the airflow to enter the flow equalization plate more smoothly, providing good preconditions for the flow equalization effect of the flow equalization plate, and ensuring the gas dispersion effect and stability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the three-dimensional structure of the boat support flow equalization plate for improving the uniformity of POLY silicon according to this utility model;

[0016] Figure 2 This is a three-dimensional structural diagram of the flow equalization plate of this utility model;

[0017] Figure 3 This is a three-dimensional structural diagram of the guide plate of this utility model;

[0018] Figure 4 This is a three-dimensional structural diagram of the combination of the flow guide hole and the flow guide chamfer of this utility model;

[0019] Figure 5 This is a three-dimensional structural diagram of the installation mechanism of this utility model.

[0020] Explanation of reference numerals in the attached drawings: 1. Flow equalization plate; 2. Flow equalization hole; 3. Flow guide plate; 4. Mounting mechanism; 401. Fixing sleeve; 402. Fixing slot; 403. Extension strip; 404. Mounting strip; 405. Mounting screw hole; 5. First fixing strip; 6. Splicing slot; 7. Second fixing strip; 8. Flow guide hole; 9. Splicing strip; 10. Flow guide chamfer. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] Polycrystalline silicon plays a crucial role in the manufacture of solar cells and is one of the key materials in the field of solar photovoltaic power generation. Polycrystalline silicon is a form of elemental silicon with a gray metallic luster. It is composed of numerous small silicon crystals with a relatively loose intercrystalline structure. It is an excellent semiconductor material with some characteristics suitable for the manufacture of solar cells.

[0023] The basic structure of a solar cell is a photovoltaic cell made by combining P-type and N-type semiconductors. Polycrystalline silicon is the key material for manufacturing this semiconductor. When sunlight shines on a solar cell made of polycrystalline silicon, electrons in silicon atoms absorb photon energy and jump from the valence band to the conduction band, forming electron-hole pairs. Under the influence of the built-in electric field of the PN junction, electrons move to the N-region and holes move to the P-region, thereby generating electromotive force and current, realizing the process of converting solar energy into electrical energy.

[0024] The quality and performance of polycrystalline silicon directly affect the conversion efficiency and stability of solar cells. High-purity polycrystalline silicon can reduce the obstruction of electron transport by impurities, making the generation and separation of electron-hole pairs more effective, thereby improving the photoelectric conversion efficiency of solar cells and increasing the output of electrical energy.

[0025] Currently, the main polycrystalline silicon purification processes on the market are the modified Siemens process and the fluidized bed process. The modified Siemens process is the most widely used and mature method. Its main process flow includes the synthesis of hydrogen chloride from chlorine and hydrogen, the synthesis of trichlorosilane gas from industrial silicon powder and hydrogen chloride and the separation and recovery of tail gas, the distillation and purification of trichlorosilane, and the feeding of high-purity trichlorosilane and high-purity hydrogen into a reduction furnace for chemical vapor deposition to generate polycrystalline silicon rods. The fluidized bed process, especially the silane fluidized bed process, is the second most important polycrystalline silicon preparation process. Its principle is to inject silane from the bottom of the fluidized bed reactor using hydrogen as a carrier and react it in the intermediate heating zone. Silicon gradually deposits on the suspended silicon seed crystals, eventually forming granular silicon. This method has advantages such as simple distillation and tail gas treatment processes, significantly reduced energy consumption and unit investment, high reaction conversion rate, low pollution, and the ability to achieve continuous production.

[0026] In the field of solar cell manufacturing, low-pressure chemical vapor deposition (LPCVD) is a core process for polycrystalline silicon preparation and plays a decisive role in the performance and quality of the cells. The traditional low-pressure chemical vapor deposition process usually adopts a three-way air intake method: furnace opening, furnace middle and furnace tail. This air intake mode has exposed significant airflow unevenness problems in actual mass production, which seriously affects the uniformity of polycrystalline silicon deposition.

[0027] From a fluid dynamics perspective, when the reactive gas enters the deposition tube from the inlet pipe outlet, due to the pressure drop and inertial effect of the gas flow within the pipe, the gas near the outlet experiences relatively less resistance and can flow more smoothly, resulting in a larger gas volume reaching the silicon wafer at that location. Conversely, the gas further away from the outlet is affected by factors such as friction against the inner wall of the pipe and collisions with other gas molecules during its flow, causing the pressure to gradually decrease and the flow rate to slow down, resulting in a smaller gas volume reaching the silicon wafer at these locations. This natural difference in airflow distribution creates a potential problem for uneven polycrystalline silicon deposition in the subsequent process.

[0028] In the specific process, the silane gas entering the furnace mouth will directly rush towards the first reaction boat at the furnace mouth due to its initial high speed and inertia. As an important raw material for polycrystalline silicon deposition, silane will undergo a decomposition reaction under high temperature environment. The decomposed silicon atoms will be deposited on the surface of the silicon wafer to form a polycrystalline silicon layer. When too much silane directly contacts the first small boat, a violent chemical reaction will occur in this area, and a large number of silicon atoms will be deposited, resulting in an excessively thick polycrystalline silicon layer in some areas. In contrast, the silicon wafers in the furnace, at the furnace tail, and far from the furnace mouth have a relatively small amount of silane gas and a lower polycrystalline silicon deposition rate. Ultimately, this results in a significant difference in the thickness of polycrystalline silicon on the silicon wafers at different locations throughout the furnace tube, especially the poor uniformity of polycrystalline silicon at the furnace mouth.

[0029] Poor uniformity of polycrystalline silicon can seriously affect the performance of solar cells. On the one hand, uneven thickness of the polycrystalline silicon layer can lead to inconsistent photoelectric conversion efficiency on the surface of the cell. In series or parallel cell modules, the "weakest link effect" can easily occur, reducing the overall power generation efficiency of the module. On the other hand, excessive thickness difference may also cause stress concentration. During the use of the cell, cracks are prone to appear in the stress concentration area, which in turn affects the lifespan and stability of the cell.

[0030] In addition, this non-uniformity increases the difficulty and cost of quality control in the production process. In order to screen out qualified products, more testing equipment and manpower are needed to conduct strict quality testing and eliminate unqualified cells. For cells with poor performance due to polycrystalline silicon non-uniformity, rework may be required, which undoubtedly increases the cost of raw materials, energy and time.

[0031] Example

[0032] like Figures 1-5 As shown, a flow equalization plate for improving the uniformity of POLY silicon includes a flow equalization plate 1, a flow guide plate 3, and an installation mechanism 4. The surface of the flow equalization plate 1 is provided with flow equalization holes 2 for improving the flow rate of the reaction gas. The flow guide plate 3 is provided behind the flow equalization plate 1 for guiding the reaction gas through the flow equalization plate 1. The flow equalization plate 1 and the flow guide plate 3 are provided on both sides for installation at the front end of the furnace mouth boat support.

[0033] Multiple sets of flow equalization holes 2 are provided, and these multiple sets of flow equalization holes 2 are evenly distributed on the surface of the flow equalization plate 1. The multiple sets of flow equalization holes 2 penetrate the flow equalization plate 1. Through the multiple sets of penetrating flow equalization holes 2, the silane gas that is concentratedly impacting the furnace mouth can be dispersed into multiple gas streams. Through the reasonable distribution of hole diameter and hole position, the gas flow rate is made more uniform in space, avoiding excessively high local gas concentration, thereby improving the uniformity of polycrystalline silicon deposition.

[0034] Multiple sets of guide holes 8 corresponding to the flow equalization holes 2 are evenly opened on the surface of the guide plate 3. A guide chamfer 10 is opened at the rear edge of each set of guide holes 8. By setting the guide holes 8 on the guide plate 3 to correspond to the flow equalization holes 2 of the flow equalization plate 1, the gas can be guided to flow orderly to the flow equalization plate 1, and the airflow diffusion turbulence can be prevented. The guide chamfer 10 can reduce the resistance of the gas when passing through the guide holes 8, so that the airflow enters the flow equalization plate 1 more smoothly and concentratedly, reducing energy loss and providing stable and orderly airflow input conditions for the flow equalization plate 1 to achieve precise flow equalization.

[0035] The flow equalization plate 1 has two sets of splicing slots 6 at its rear end. The two sets of splicing slots 6 are evenly distributed on both sides of the rear end edge of the flow equalization plate 1. The splicing slots 6 facilitate the quick and accurate splicing of the flow equalization plate 1 and the flow guide plate 3, ensuring that the positions of the two are fixed, so that after the gas is guided by the flow guide plate 3, it can accurately pass through the corresponding channels of the flow guide hole 8 and the flow equalization hole 2.

[0036] The front end of the flow guide plate 3 is provided with two sets of splicing clips 9. The two sets of splicing clips 9 are symmetrically arranged along the two sides of the front end of the flow guide plate 3. The splicing clips 9 match and engage with the splicing slots 6. The splicing clips 9 and the splicing slots 6 are tightly engaged to form a stable connection structure, preventing the flow equalization plate 1 and the flow guide plate 3 from being relatively displaced under the impact of gas.

[0037] Both sides of the flow equalization plate 1 are provided with first fixing strips 5, and both sides of the flow guide plate 3 are provided with second fixing strips 7 corresponding to the first fixing strips 5. The first fixing strips 5 and the second fixing strips 7 are superimposed to facilitate the combination and fixation by the installation mechanism 4.

[0038] The installation mechanism 4 includes a fixing sleeve 401. The inner side of the fixing sleeve 401 is provided with a fixing groove 402 to accommodate the first fixing strip 5 and the second fixing strip 7. The first fixing strip 5 and the second fixing strip 7 are engaged by the fixing groove 402, so that the flow equalization plate 1, the flow guide plate 3 and the installation mechanism 4 are firmly connected. This connection method allows the device to be quickly installed and disassembled at the furnace mouth, and the engaging structure has a certain buffering capacity to adapt to the slight thermal expansion and contraction of the device during operation.

[0039] An extension strip 403 is provided at the rear edge of the fixed sleeve 401, and an installation strip 404 for fitting the boat support is provided at the rear end of the extension strip 403. Multiple sets of installation screw holes 405 are evenly opened on the surface of the installation strip 404. The fixed sleeve 401 can be tightly fitted to the boat support through the extension strip 403 and the installation strip 404, increasing the contact area between the device and the boat support and enhancing the installation stability. The installation screw holes 405 facilitate the firm fixing of the device to the boat support, ensuring that the position of the flow equalization plate 1 and the flow guide plate 3 remains unchanged during operation, so that the gas always flows through the flow guide plate 3 and the flow equalization plate 1 along the preset path, and continuously plays the role of uniform gas flow.

[0040] During operation, the workers first splice the flow equalization plate 1 and the flow guide plate 3 using the splicing slot 6 and splicing strip 9, ensuring that the splicing strip 9 is accurately inserted into the splicing slot 6 to complete the initial fixation of the two. Then, the first fixing strip 5 on both sides of the flow equalization plate 1 and the second fixing strip 7 on both sides of the flow guide plate 3 are aligned and superimposed. Next, the fixing slot 402 of the fixing sleeve 401 is aligned with the superimposed first fixing strip 5 and second fixing strip 7 to make them snap together. Then, the entire device is attached to the designated position at the front end of the furnace mouth boat support using the extension strip 403 and the mounting strip 404 at the rear end of the fixing sleeve 401. Using the mounting screw holes 405 on the surface of the mounting strip 404, screws and other fasteners are used to firmly fix the device to the boat support.

[0041] Its working principle is as follows: During the low-pressure chemical vapor deposition process, silane gas enters from the furnace opening. At this time, the guide plate 3 plays a role. Multiple sets of guide holes 8 evenly opened on its surface correspond to the flow equalization holes 2 of the flow equalization plate 1, guiding the gas to flow orderly to the flow equalization plate 1. The guide chamfer 10 at the rear edge of the guide hole 8 can reduce the resistance when the gas passes through, allowing the airflow to enter the flow equalization plate 1 more smoothly and in a concentrated manner, reducing energy loss, and providing stable and orderly airflow input conditions for the flow equalization plate 1 to achieve precise flow equalization. When the gas flows through the flow equalization plate 1, the multiple sets of through flow equalization holes 2 on the surface of the flow equalization plate 1 disperse the silane gas that originally concentratedly impacted the furnace opening into multiple airflows. Through the reasonable distribution of the aperture and position of the flow equalization holes 2, the gas flow rate is more uniform in space, avoiding the situation of excessively high local gas concentration. In this way, the dispersed gas no longer concentrates to impact the first reaction boat at the furnace opening, thereby improving the uniformity of polycrystalline silicon deposition.

[0042] Its beneficial effects are significant. By using the flow equalization plate 1 in conjunction with the flow equalization holes 2, silane gas is effectively dispersed, avoiding concentrated gas impact and making polycrystalline silicon deposition more uniform. This solves the problem of poor polycrystalline silicon uniformity at the furnace mouth in traditional processes. In terms of actual effect, it can significantly improve the uniformity within the first small boat from a high level, for example, from 17.41% to about 5.19%, greatly improving the passivation performance of the back of the cell. Through the fixing sleeve 401, extension strip 403 and mounting strip 404 of the mounting mechanism 4, the device is firmly connected to the boat support. This connection method not only ensures the stability of the device during operation, but also adapts to certain thermal expansion and contraction, reducing the impact of displacement and other issues on the flow equalization effect. Through the design of the flow guide holes 8 and flow guide chamfer 10 on the flow guide plate 3, the gas is guided to flow in an orderly manner, reducing resistance and allowing the airflow to enter the flow equalization plate 1 more smoothly, providing good preconditions for the flow equalization effect of the flow equalization plate 1, and ensuring the gas dispersion effect and stability.

Claims

1. A flow equalization plate for improving the uniformity of polysilicon, comprising a flow equalization plate (1); characterized in that, It also includes a guide plate (3) and an installation mechanism (4); the surface of the flow equalization plate (1) is provided with flow equalization holes (2) for improving the flow rate of the reaction gas, and a guide plate (3) is provided behind the flow equalization plate (1) for guiding the reaction gas through the flow equalization plate (1). Both sides of the flow equalization plate (1) and the guide plate (3) are provided with installation mechanisms (4) for installation at the front end of the furnace mouth boat support. Both sides of the flow equalization plate (1) are provided with first fixing strips (5), and both sides of the guide plate (3) are provided with corresponding first fixing strips. The second fixing strip (7) of the fixing strip (5) and the installation mechanism (4) include a fixing sleeve (401). The inner side of the fixing sleeve (401) is provided with a fixing groove (402) to accommodate the first fixing strip (5) and the second fixing strip (7). An extension strip (403) is provided at the rear edge of the fixing sleeve (401). An installation strip (404) that fits the boat support is provided at the rear end of the extension strip (403). Multiple sets of installation screw holes (405) are evenly opened on the surface of the installation strip (404).

2. The boat support flow equalization plate for improving the uniformity of POLY silicon according to claim 1, characterized in that, Multiple sets of flow equalization holes (2) are provided, and the multiple sets of flow equalization holes (2) are evenly distributed on the surface of the flow equalization plate (1). The multiple sets of flow equalization holes (2) penetrate the flow equalization plate (1).

3. The boat support flow equalization plate for improving the uniformity of POLY silicon according to claim 2, characterized in that, The surface of the guide plate (3) is uniformly provided with multiple sets of guide holes (8) corresponding to the flow equalization holes (2), and the rear edge of each set of guide holes (8) is provided with a guide chamfer (10).

4. The boat support flow equalization plate for improving the uniformity of POLY silicon according to claim 3, characterized in that, The flow equalization plate (1) has two sets of splicing slots (6) at its rear end, and the two sets of splicing slots (6) are evenly distributed on both sides of the rear end edge of the flow equalization plate (1).

5. A boat-supported flow equalizer for improving the uniformity of POLY silicon according to claim 4, characterized in that, The front end of the guide plate (3) is provided with two sets of splicing clips (9). The two sets of splicing clips (9) are symmetrically arranged along the two sides of the front end of the guide plate (3). The splicing clips (9) are matched and engaged with the splicing slots (6).

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