A vertical quartz boat

Abstract

The utility model provides a vertical quartz boat for improving the stress uniformity of boat column, be used for the technical field of silicon wafer production, including roof, bottom plate and boat column, boat column includes first boat column, second boat column, third boat column and fourth boat column, with the center of bottom plate as the center, the center angle of the circle arc corresponding between the bottom center of first boat column and the bottom center of second boat column is alpha, the center angle of the circle arc corresponding between the bottom center of third boat column and the bottom center of fourth boat column is beta, and satisfy alpha greater than beta, 60 DEG less than or equal to beta 120 DEG. The utility model discloses through the fine design to the boat column layout of quartz boat, can effectively reduce the partial boat column stress too concentrated due to the geometric asymmetry, reduces the tensile stress that boat column received when thermal expansion simultaneously, effectively avoids the crack due to stress concentration, further avoids the boat column burst, significantly improves the service life of quartz boat, saves the production cost.

Description

Technical Field

[0001] This utility model belongs to the field of silicon wafer production technology, and in particular relates to a vertical quartz boat. Background Technology

[0002] In silicon wafer production, silicon wafers are placed on quartz boats, which are then placed in a diffusion furnace for diffusion processing. Since the diffusion process involves temperatures above 650°C, the quartz boats undergo linear expansion under prolonged exposure to these temperatures. This results in microscopic deformation at the connections between the boat pillars and the top and bottom plates, generating tensile thermal stress. Existing vertical quartz boats consist of five pillars forming a pentagonal layout with the long side significantly larger than the short side. This layout makes the connections between some pillars and the top or bottom plates more prone to cracking due to stress concentration caused by geometric asymmetry, thermal expansion mismatch during diffusion, and thermal cycling fatigue. This not only affects the lifespan of the quartz boat but also leads to abnormal silicon wafer thickness and geometric parameters during diffusion, requiring rework or scrapping of the product, negatively impacting production efficiency and costs. Utility Model Content

[0003] To solve the above-mentioned technical problems, this utility model provides a vertical quartz boat that avoids the boat column from cracking and extends the service life of the quartz boat.

[0004] The technical solution adopted by this utility model is: a vertical quartz boat, including a top plate, a bottom plate, and boat columns. The top plate and the bottom plate are parallel and spaced apart. The two ends of the boat columns are fixedly connected to the top plate and the bottom plate, respectively. There are multiple boat columns, which are arranged parallel and spaced apart along the circumference of the bottom plate or the top plate. Each boat column has a toothed groove, and the multiple toothed grooves together define a receiving cavity, in which a silicon wafer is suitable for placement.

[0005] A straight line coplanar with the base plate and passing through its center is defined as a first reference line. A straight line coplanar with the base plate, passing through its center, and perpendicular to the first reference line is defined as a second reference line. The pontoons include a first pontoon, a second pontoon, a third pontoon, and a fourth pontoon. The first pontoons and the second pontoons are axially symmetrical with respect to the first reference line. The third pontoons and the fourth pontoons are axially symmetrical with respect to the first reference line. The first pontoons and the second pontoons are located on one side of the second reference line, and the third pontoons and the fourth pontoons are located on the other side of the second reference line.

[0006] With the center of the base plate as the center, the central angle corresponding to the arc between the center of the bottom surface of the first boat post and the center of the bottom surface of the second boat post is α, and the central angle corresponding to the arc between the center of the bottom surface of the third boat post and the center of the bottom surface of the fourth boat post is β, and α > β, 60° ≤ β ≤ 120°.

[0007] Furthermore, 160°≤α≤170.

[0008] Furthermore, α = 165°.

[0009] Furthermore, β = 90°.

[0010] Furthermore, the tooth groove includes a lower limiting surface, an upper limiting surface, and a side limiting surface. The upper limiting surface, the side limiting surface, and the lower limiting surface form an opening facing radially inward. The upper limiting surface and the lower limiting surface are arranged in parallel and spaced apart. The side limiting surface is connected to the upper limiting surface and the lower limiting surface, respectively. A first chamfer is formed between the lower limiting surface and the side limiting surface, and a second chamfer is formed between the upper limiting surface and the side limiting surface.

[0011] Furthermore, the first chamfer radius is R1 and the second chamfer radius is R2, and they satisfy 0.15mm ≤ R1 ≤ 0.3mm and 0.15mm ≤ R2 ≤ 0.3mm.

[0012] Furthermore, the groove depth of the tooth is D, the height of the tooth is H, and satisfies 3.8mm≤D≤4.2mm, 2.4mm≤H≤2.6mm, and R1=R2.

[0013] Furthermore, the radius R1 of the first chamfer and the radius R2 of the second chamfer are equal, and satisfy R1=R2=0.25mm.

[0014] Furthermore, the vertical quartz boat is adapted to one of 5-inch, 6-inch, or 8-inch silicon wafers.

[0015] Furthermore, the center of the bottom plate or the center of the top plate of the vertical quartz boat is on the same axis as the center of the silicon wafer inside the receiving cavity.

[0016] The advantages and positive effects of this utility model are:

[0017] (1) This application can effectively reduce the stress concentration of some boat pillars due to geometric asymmetry by refining the boat pillar layout of the quartz boat, and at the same time reduce the tensile stress on the boat pillars when the four boat pillars are thermally expanded, effectively avoiding cracks caused by stress concentration, and thus avoiding the phenomenon of accelerated propagation of fatigue cracks and breakage of the boat pillars under thermal cycling; significantly improving the service life of the quartz boat, ensuring the production quality of silicon wafers, and saving production costs.

[0018] (2) The side limiting surface of the tooth groove forms a first chamfer and a second chamfer with the upper limiting surface and the lower limiting surface, respectively, which effectively reduces the stress concentration coefficient of the inner corner of the tooth groove and further reduces the risk of breakage of the pontoon. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the position of the hull column in a quartz boat in the prior art;

[0020] Figure 2 This is a schematic diagram of a quartz boat structure according to a specific embodiment of this utility model;

[0021] Figure 3 This is a schematic diagram of the position of the quartz boat's pillars according to a specific embodiment of this utility model;

[0022] Figure 4 This is a schematic diagram of the tooth groove structure of a specific embodiment of this utility model.

[0023] In the picture:

[0024] 1. Top plate; 2. Silicon wafer; 3. First boat post; 4. Second boat post; 5. Third boat post; 6. Fourth boat post; 7. Fifth boat post; 8. Bottom plate; 9. First chamfer; 10. Second chamfer; 11. Lower limit surface; 12. Upper limit surface; 13. Side limit surface; a. First reference line; b. Second reference line. Detailed Implementation

[0025] The embodiments of this utility model will now be described with reference to the accompanying drawings.

[0026] Figure 1This illustration shows a vertical quartz boat in the prior art, comprising a top plate 1, a bottom plate 8, and boat columns. The top plate 1 and the bottom plate 8 are parallel and spaced apart. The two ends of the boat columns are fixedly connected to the top plate 1 and the bottom plate 8, respectively. There are multiple boat columns, which are arranged parallel and spaced apart along the circumference of the bottom plate 8 or the top plate 1. Each boat column has a toothed groove, which together define a receiving cavity, into which a silicon wafer is placed. A straight line coplanar with the bottom plate 8 and passing through the center of the bottom plate 8 is defined as a first reference line a, and a straight line coplanar with the bottom plate 8, passing through the center of the bottom plate, and perpendicular to the first reference line a is defined as a second reference line b. The boat columns include a first boat column 3, a second boat column 4, a third boat column 5, a fourth boat column 6, and a fifth boat column 7. The first boat column 3 and the second boat column 4 are axially symmetrical with respect to the first reference line a, and the third boat column... 5 and the fourth boat pillar 6 are symmetrically arranged with respect to the first reference line a. The first boat pillar 3, the second boat pillar 4, the third boat pillar 5, and the fourth boat pillar 6 are all located close to the second reference line b. The fifth boat pillar 7 is located on the side away from the first boat pillar 3 and the second boat pillar 4. The bottom centers of the first boat pillar 3, the second boat pillar 4, the third boat pillar 5, the fourth boat pillar 6, and the fifth boat pillar 7 form a pentagon when connected sequentially. The distance between the fourth boat pillar 6 and the fifth boat pillar 7 is less than the distance between the second boat pillar 4 and the first boat pillar 3, and the ratio of the two distances can even reach 1:20. In the prior art, during silicon wafer diffusion, the vertical quartz boat is placed in the diffusion furnace, and the reaction gas flows along the extension direction of the second reference line b. Specifically, the reaction gas is blown from the direction of the second boat pillar 4 and the fourth boat pillar 6 towards the direction of the first boat pillar 3 and the third boat pillar 5.

[0027] In practical use, the connection points between the third and fourth boat pillars 5 and the top plate 1 of the existing vertical quartz boat are prone to cracking. The main reason is stress concentration caused by geometric asymmetry. Because the ratio of the short side to the long side of the pentagon formed by the five boat pillars in the existing technology is extreme, with the short side only 5% of the long side, forming an extremely flat rectangular structure with a single-point extension, the third and fourth boat pillars 5 and 6 must bear the additional bending moment caused by the geometric abrupt change, resulting in relatively concentrated stress on them. Furthermore, the thermal expansion mismatch during the diffusion process further exacerbates this stress concentration, as the linear expansion of quartz at 650℃ is approximately 0. The thermal expansion in this region is limited, resulting in a 0.6% increase in thermal stress (along the length of the boat pillars). However, the extremely small spacing between the first boat pillar 3 and the third boat pillar 5, and between the second boat pillar 4 and the fourth boat pillar 6, causes strong tensile stress on these four boat pillars. The third boat pillar 5 and the fourth boat pillar 6 each experience two opposite tensile stresses, leading to greater stress concentration and a higher likelihood of crack formation. Simultaneously, due to frequent temperature fluctuations within the furnace during diffusion, the first boat pillar 3 and the third boat pillar 5, and the second boat pillar 4 and the fourth boat pillar 6, undergo repeated compression-tension cycles due to their different expansion rates. Under the influence of thermal cycling fatigue, the fatigue cracks in the third boat pillar 5 and the fourth boat pillar 6 propagate more rapidly, eventually leading to fracture. In other words, the third boat pillar 5 and the fourth boat pillar 6 are more prone to fracture under the combined effects of stress concentration caused by geometric asymmetry, thermal expansion mismatch during diffusion, and thermal cycling fatigue. To address the aforementioned technical problems, this application proposes a vertical quartz boat that improves the stress uniformity of the boat columns. This reduces excessive stress concentration in some boat columns due to geometric asymmetry and decreases the tensile stress on the boat columns during thermal expansion. This effectively avoids cracks caused by stress concentration and prevents the boat columns from collapsing due to accelerated fatigue crack propagation under thermal cycling.

[0028] like Figures 2 to 3As shown, this application proposes a vertical quartz boat, including a top plate 1, a bottom plate 8, and boat columns. The top plate 1 and the bottom plate 8 are parallel and spaced apart. The two ends of the boat columns are fixedly connected to the top plate 1 and the bottom plate 8, respectively. There are multiple boat columns, which are arranged parallel and spaced apart along the circumference of the bottom plate 8 or the top plate 1. Each boat column has a toothed groove, and the multiple toothed grooves together define a receiving cavity, in which a silicon wafer is suitable for placement. A straight line coplanar with the bottom plate 8 and passing through the center of the bottom plate 8 is defined as a first reference line a, and a straight line coplanar with the bottom plate 8, passing through the center of the bottom plate, and perpendicular to the first reference line a is defined as a second reference line b. Unlike the prior art, the boat columns include a first boat column 3. The second boat post 4, the third boat post 5, and the fourth boat post 6 are arranged symmetrically with respect to the first reference line a. The first boat post 3 and the second boat post 4 are located on one side of the second reference line b, and the third boat post 5 and the fourth boat post 6 are located on the other side. With the center of the base plate 8 as the center, the central angle α corresponding to the arc between the center of the bottom surface of the first boat post 3 and the center of the bottom surface of the second boat post 4 is denoted as α, and the central angle β corresponding to the arc between the center of the bottom surface of the third boat post 5 and the center of the bottom surface of the fourth boat post 6 is denoted as β, satisfying α > β and 60° ≤ β ≤ 120°. This arrangement of the boat posts within the quartz boat makes the four boat posts more dispersed compared to existing designs, reducing stress concentration caused by geometric asymmetry and tensile stress on the boat posts during thermal expansion. This effectively avoids cracks caused by stress concentration, thus preventing the boat posts from cracking under thermal cycling.

[0029] In existing technologies, such as Figure 1As shown, the first boat post 3, the second boat post 4, the third boat post 5, and the fourth boat post 6 are all located close to the second reference line b. The first boat post 3 and the second boat post 4 are located on one side of the second reference line b, while the third boat post 5, the fourth boat post 6, and the fifth boat post 7 are located on the other side of the second reference line b. The fifth boat post 7 is located far away from the first boat post 3 and the second boat post 4. The lines connecting the centers of the bottom surfaces of the five boat posts form a pentagonal layout with different side lengths. The length of the short side is only 5% of the length of the long side. Due to the geometric asymmetry of this layout, the third boat post 5 and the fourth boat post 6 experience stress concentration. This, combined with the thermal expansion mismatch during the diffusion process and the thermal cycling fatigue effect, causes the third boat post 5 and the fourth boat post 6 to experience excessive stress, resulting in random fractures. In this technical solution, only four boat pillars are set, and the positions of the four boat pillars are adjusted. The inventors of this application have discovered that, under the condition that the reactant gas is blown from the second boat pillar 4 and the fourth boat pillar 6 towards the first boat pillar 3 and the third boat pillar 5, when the central angle corresponding to the arc between the bottom center of the first boat pillar 3 and the bottom center of the second boat pillar 4 is α, and the central angle corresponding to the arc between the bottom center of the third boat pillar 5 and the bottom center of the fourth boat pillar 6 is β, and satisfying α>β and 60°≤β≤120°, it can effectively Improving the geometric symmetry of the four boat pillars significantly reduces stress concentration in the third boat pillar 5 and the fourth boat pillar 6. It also reduces excessive tensile stress on the third boat pillar 5 and the fourth boat pillar 6 during thermal expansion, resulting in a more uniform stress distribution across the four boat pillars. This prevents excessive stress concentration in any one boat pillar, thus effectively reducing the likelihood of cracking at the connection between the boat pillars and the top plate 1, extending the lifespan of the boat pillars, ensuring the production quality of the silicon wafer 2, and saving production costs.

[0030] This technical solution can be understood as follows: β can be 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, or 120°, and α > β. The reacting gas is blown from the second boat column 4 and the fourth boat column 6 towards the first boat column 3 and the third boat column 5. The four boat columns inside this three-dimensional quartz boat are relatively dispersed, and the stress they receive is relatively uniform. This can effectively avoid the phenomenon of excessive stress concentration in a certain boat column, reduce the breakage rate of the boat column, and extend the service life of the quartz boat.

[0031] Specifically, in one specific embodiment of this application, the central angle α corresponding to the arc between the center of the bottom surface of the first pontoon 3 and the center of the bottom surface of the second pontoon 4 is set to 160°≤α≤170°, and α can be any value among 160°, 161°, 162°, 163°, 164°, 165°, 166°, 167°, 168°, 169°, and 170°. In this technical solution, α > β, so the space corresponding to angle α is suitable for placing the silicon wafer in the receiving cavity, which facilitates the silicon wafer to enter / exit the receiving cavity. At the same time, 60° ≤ β ≤ 120°, and β can be any value among 60°, 65°, 70°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 110°, 115°, and 120°, or any value within the range of any two. The position design of the four boat pillars in this application can not only provide stable support for the silicon wafer 2, but also improve the geometric symmetry of the distribution of the four boat pillars, so that the stress on different boat pillars is more uniform, effectively avoiding the boat pillar cracking caused by excessive stress concentration at the connection between a certain boat pillar and the top plate 1.

[0032] Furthermore, when the central angle β corresponding to the arc between the center of the bottom surface of the third boat post 5 and the center of the bottom surface of the fourth boat post 6 is set to 90°, it can not only provide stable support for the silicon wafer 2 and improve the geometric symmetry of the distribution of the four boat posts, but also better adapt to the existing wafer-turning fixture, making it easier to smoothly pick up and put down the silicon wafer 2 without causing defects such as scratches or slippage.

[0033] Preferably, the central angle α corresponding to the arc between the center of the bottom surface of the first boat post 3 and the center of the bottom surface of the second boat post 4 is set to 165°, and the central angle β corresponding to the arc between the center of the bottom surface of the third boat post 5 and the center of the bottom surface of the fourth boat post 6 is set to 90°. At this time, the four boat posts can cooperate in a coordinated manner, which can effectively avoid excessive stress concentration in the boat posts and cracking, while meeting the requirements of convenient silicon wafer loading / unloading, stable support for silicon wafers, and compatibility with wafer flipping fixtures, thus improving the practicality of the quartz boat.

[0034] Furthermore, such as Figure 4As shown, the tooth groove in this application includes a lower limiting surface 11, an upper limiting surface 12, and a side limiting surface 13. The upper limiting surface 12, the side limiting surface 13, and the lower limiting surface 11 form an opening facing radially inward. The upper limiting surface 12 and the lower limiting surface 11 are arranged parallel and spaced apart, and the side limiting surface 13 is connected to the upper limiting surface 12 and the lower limiting surface 11 respectively. A first chamfer 9 is formed between the lower limiting surface 11 and the side limiting surface 13, and a second chamfer 10 is formed between the upper limiting surface 12 and the side limiting surface 13. In the prior art, the connection points between the side limiting surface 13 and the upper limiting surface 12 and the lower limiting surface 11 are right-angled structures. The stress concentration coefficient of the right-angled structure is relatively high. With the extension of the service time, polycrystalline material tends to accumulate at the right-angled structure, causing the stress concentration coefficient to continue to increase, increasing the risk of breakage of the boat post at the tooth groove. In this technical solution, the original right-angle structure is designed as a chamfered structure, which can significantly reduce the stress concentration factor in this part, while also reducing polycrystalline accumulation, further improving the stress distribution of the boat pillar, and reducing the risk of boat pillar fracture.

[0035] In one specific embodiment of this application, the radius of the first chamfer 9 is R1, and the radius of the second chamfer 10 is R2, satisfying 0.15 mm ≤ R1 ≤ 0.3 mm and 0.15 mm ≤ R2 ≤ 0.3 mm. This design can effectively reduce the stress concentration factor of the chamfer portion of the tooth groove away from the opening-side limiting surface 13.

[0036] In one specific embodiment of this application, the groove depth is D, the height is H, and the conditions 3.8mm≤D≤4.2mm, 2.4mm≤H≤2.6mm, and R1=R2 are met, which can effectively reduce the stress concentration factor at the corner of the inner side of the groove.

[0037] Preferably, in the above embodiment, R1=R2=0.25mm. This setting reduces the stress concentration factor at the chamfered portion while also improving the uniformity of airflow distribution within the quartz boat, resulting in more uniform polycrystalline deposition at the chamfered portion, further improving the stress distribution of the boat pillar, and reducing the risk of boat pillar fracture.

[0038] Furthermore, the vertical quartz boat proposed in this application for improving the uniformity of boat column stress can be configured according to the specifications of silicon wafer 2, so that the receiving cavity is adapted to one of 5-inch, 6-inch or 8-inch silicon wafer 2, which can reduce boat column cracking and improve the service life of the boat column.

[0039] In this embodiment, the center of the bottom plate 8 or the center of the top plate 1 of the vertical quartz boat is on the same axis as the center of the silicon wafer 2 in the cavity. The silicon wafer 2 can be stably placed in the cavity, and the airflow can act more evenly on the silicon wafer 2 to achieve a good diffusion effect.

[0040] The technical solution of this application will be described in detail below with reference to specific embodiments.

[0041] Example 1

[0042] like Figure 3 As shown, a vertical quartz boat is used in the diffusion process of a 6-inch silicon wafer 2. It includes a top plate 1, a bottom plate 8, and four boat pillars disposed between the top plate 1 and the bottom plate 8. A straight line coplanar with the bottom plate 8 and passing through its center is defined as a first reference line a, and a straight line coplanar with the bottom plate 8, passing through its center, and perpendicular to the first reference line a is defined as a second reference line b. Unlike existing technologies, the boat pillars include a first boat pillar 3, a second boat pillar 4, a third boat pillar 5, and a fourth boat pillar 6. The first boat pillar 3 and the second boat pillar 4 are axially aligned with the first reference line a. The third and fourth boat pillars are symmetrically arranged with respect to the first reference line a. The first and second boat pillars are located on one side of the second reference line b, and the third and fourth boat pillars are located on the other side of the second reference line b. With the center of the base plate 8 as the center, the central angle corresponding to the arc between the bottom center of the first boat pillar 3 and the bottom center of the second boat pillar 4 is α, which is set to 165°; the central angle corresponding to the arc between the bottom center of the third boat pillar 5 and the bottom center of the fourth boat pillar 6 is β, which is set to 90°.

[0043] The gantry has a toothed groove with a groove depth D of 4 mm and a height H of 2.5 mm. The groove includes a lower limiting surface 11, an upper limiting surface 12, and a side limiting surface 13. These surfaces form an opening facing radially inward. The upper limiting surface 12 and lower limiting surface 11 are parallel and spaced apart, and the side limiting surface 13 connects to both. A first chamfer 9 is formed between the lower limiting surface 11 and the side limiting surface 13, and a second chamfer 10 is formed between the upper limiting surface 12 and the side limiting surface 13. The radius of the first chamfer 9 is R1, and the radius of the second chamfer 10 is R2, where R1 = R2 = 0.25 mm. The calculated stress concentration factor at the chamfered area is 1.1.

[0044] The vertical quartz boat was placed in a diffusion furnace for silicon wafer diffusion. The gas flow direction in the diffusion furnace was from the direction of the second boat pillar 4 and the fourth boat pillar 6 to the direction of the first boat pillar 3 and the third boat pillar 5. No boat pillars broke. After multiple uses, the polycrystalline film thickness of each boat pillar could accumulate to 60um. After etching, the boat was reused 3 times without any breakage.

[0045] Comparative Example 1

[0046] A vertical quartz boat is used in the diffusion process of a 6-inch silicon wafer 2. Unlike the first embodiment, the connection between the side limiting surface 13 of the toothed groove on the boat column and the upper limiting surface 12 and the lower limiting surface 11 is a right-angle structure. The stress concentration factor of the right-angle structure is calculated to be 2.3.

[0047] The vertical quartz boat was placed in a diffusion furnace for silicon wafer diffusion. After being used the same number of times as in Example 1, the connection between the side limiting surface 13 of the tooth groove and the upper limiting surface 12 and the lower limiting surface 11 was observed. The polycrystalline deposition was significantly greater than the polycrystalline deposition thickness of the chamfered structure used in Example 1. After multiple uses, the boat column broke at the tooth groove.

[0048] Comparative Example 2

[0049] like Figure 1 As shown, a vertical quartz boat in the prior art is used in the diffusion process of a 6-inch silicon wafer 2. It includes a top plate 1, a bottom plate 8, and five boat pillars disposed between the top plate 1 and the bottom plate 8, namely a first boat pillar 3, a second boat pillar 4, a third boat pillar 5, a fourth boat pillar 6, and a fifth boat pillar 7. The first boat pillar 3 and the second boat pillar 4 are axially symmetrical with respect to a first reference line a and are located on one side of a second reference line b. The third boat pillar 5 and the fourth boat pillar are also axially symmetrical with respect to the first reference line a and are located on the other side of the second reference line b. The central angle corresponding to the arc between the bottom center of the first boat pillar 3 and the bottom center of the second boat pillar 4 is α, which is set to 165°. The central angle corresponding to the arc between the bottom center of the third boat pillar 5 and the bottom center of the fourth boat pillar 6 is β, which is set to 155°.

[0050] The pontoon column is provided with a toothed groove. The groove depth D is set to 4mm and the height H is set to 2.5mm. The connection between the side limiting surface 13 of the toothed groove and the upper limiting surface 12 and the lower limiting surface 11 are all right-angle structures. The stress concentration factor is calculated to be 2.3.

[0051] The vertical quartz boat was placed in the same diffusion furnace as in Example 1 for silicon wafer diffusion. When the polycrystalline film thickness on the fourth boat pillar 6 accumulated to 24 μm, the connection between the fourth boat pillar 6 and the top plate 1 cracked. After multiple tests, the vertical quartz boat with this structure cracked at the connection between the fourth boat pillar 6 and the top plate 1 in 100% of cases.

[0052] Comparison shows that using the vertical quartz boat proposed in this application effectively avoids cracking at the connection between the boat column and the top plate 1 or the bottom plate 8, as well as at the toothed groove, thus significantly improving the service life of the quartz boat.

[0053] In some other embodiments of this application, vertical quartz boats of corresponding sizes are designed according to the structural design in Embodiment 1, based on the specifications of 5-inch and 8-inch silicon wafers 2, and placed in the same diffusion furnace as in Embodiment 1 for silicon wafer diffusion. After multiple uses, the polycrystalline film thickness can be accumulated to 60 μm without any breakage.

[0054] The advantages and positive effects of this utility model are:

[0055] This application, through a refined design of the quartz boat's pillar layout, effectively reduces excessive stress concentration in some pillars due to geometric asymmetry. It also reduces the tensile stress on the pillars during thermal expansion, effectively preventing cracks caused by stress concentration and avoiding accelerated fatigue crack propagation and breakage of the pillars under thermal cycling. This significantly improves the service life of the quartz boat, ensures the production quality of silicon wafers, and saves production costs.

[0056] By setting a first chamfer and a second chamfer in the tooth groove, the stress concentration factor of the chamfered part at the end of the side limiting surface away from the opening is effectively reduced, further reducing the risk of breakage of the pontoon.

[0057] The embodiments of this utility model have been described in detail above, but the content described is only a preferred embodiment of this utility model and should not be considered as limiting the scope of implementation of this utility model. All equivalent changes and improvements made in accordance with the claims of this utility model should still fall within the patent coverage of this utility model.

Claims

1. A vertical quartz boat, characterized in that: The device includes a top plate (1), a bottom plate (8), and boat columns. The top plate (1) and the bottom plate (8) are parallel and spaced apart. The two ends of the boat columns are fixedly connected to the top plate (1) and the bottom plate (8), respectively. There are multiple boat columns, which are arranged parallel and spaced apart along the circumference of the bottom plate (8) or the top plate (1). Each boat column has a toothed groove, and the multiple toothed grooves together define a receiving cavity. A silicon wafer (2) is suitable for being placed in the receiving cavity. The device is characterized in that: A straight line coplanar with the base plate (8) and passing through the center of the base plate (8) is defined as the first reference line. A straight line coplanar with the base plate (8) and passing through the center of the base plate (8) and perpendicular to the first reference line is defined as the second reference line. The boat pillars include a first boat pillar (3), a second boat pillar (4), a third boat pillar (5), and a fourth boat pillar (6). The first boat pillar (3) and the second boat pillar (4) are axially symmetrical with respect to the first reference line. The third boat pillar (5) and the fourth boat pillar (6) are axially symmetrical with respect to the first reference line. The first boat pillar (3) and the second boat pillar (4) are located on one side of the second reference line, and the third boat pillar (5) and the fourth boat pillar (6) are located on the other side of the second reference line. With the center of the base plate (8) as the center, the central angle corresponding to the arc between the center of the bottom surface of the first boat post (3) and the center of the bottom surface of the second boat post (4) is α, and the central angle corresponding to the arc between the center of the bottom surface of the third boat post (5) and the center of the bottom surface of the fourth boat post (6) is β, and α > β, 60° ≤ β ≤ 120°.

2. The vertical quartz boat according to claim 1, characterized in that: 160°≤α≤170。 3. The vertical quartz boat according to claim 2, characterized in that: The value of α is 165°.

4. The vertical quartz boat according to any one of claims 1-3, characterized in that: The value of β is 90°.

5. The vertical quartz boat according to claim 1, characterized in that: The tooth groove includes a lower limiting surface (11), an upper limiting surface (12), and a side limiting surface (13). The upper limiting surface (12), the side limiting surface (13), and the lower limiting surface (13) form an opening facing radially inward. The upper limiting surface (12) and the lower limiting surface (11) are arranged parallel and spaced apart. The side limiting surface (13) is connected to the upper limiting surface (12) and the lower limiting surface (11) respectively. A first chamfer (9) is formed between the lower limiting surface (11) and the side limiting surface (13). A second chamfer (10) is formed between the upper limiting surface (12) and the side limiting surface (13).

6. The vertical quartz boat according to claim 5, characterized in that: The radius of the first chamfer (9) is R1, and the radius of the second chamfer (10) is R2, and the following conditions are met: 0.15 mm ≤ R1 ≤ 0.3 mm, 0.15 mm ≤ R2 ≤ 0.3 mm.

7. The vertical quartz boat according to claim 6, characterized in that: The groove depth is D, the groove height is H, and the following conditions are met: 3.8mm≤D≤4.2mm, 2.4mm≤H≤2.6mm, and R1=R2.

8. The vertical quartz boat according to claim 7, characterized in that: The radius R1 of the first chamfer (9) and the radius R2 of the second chamfer (10) are equal, and satisfy R1=R2=0.25mm.

9. The vertical quartz boat according to claim 1, characterized in that: The vertical quartz boat is adapted to one of 5-inch, 6-inch or 8-inch silicon wafers (2).

10. The vertical quartz boat according to claim 1, characterized in that, The center of the bottom plate (8) or the center of the top plate (1) of the vertical quartz boat is on the same axis as the center of the silicon wafer (2) in the cavity.

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