Gas-phase heavy doping device
By optimizing the quartz bell structure of the gas-phase heavily doped doping device, especially the inclined bending design of the material box placement cavity, the problem of low utilization rate of N-type silicon wafers is solved, and a more efficient doping process and cost reduction is achieved.
Patent Information
- Application Number
- CN202421539314.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-01
- Publication Date
- 2025-07-01
- Estimated Expiration
- 2034-07-01
AI Technical Summary
In the prior art, the dopant utilization rate during the doping process of N-type silicon wafers is low, resulting in waste of raw materials and increased costs, especially the waste of high-purity P elements.
The quartz bell cover structure of the gas phase heavily doping doping device is improved, especially the side wall of the material box placement cavity, designed as an inclined and bent second flow guide, forming a cone structure, reducing the volume of the material box placement cavity, and optimizing the air flow path to improve doping efficiency.
By optimizing the airflow path, it reduces the dopant usage, improves doping efficiency, reduces production costs, and achieves higher dopant utilization and shorter doping times.
Smart Images
Figure CN223047640U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and particularly to a gas-phase heavy doping device. Background Art
[0002] In the field of semiconductor manufacturing, as the basic material for integrated circuits, the conductivity of a wafer is a key factor in manufacturing high-performance semiconductor devices. To regulate the conductivity of the silicon wafer, it is usually necessary to dope the silicon crystal to change its internal electronic structure. Currently, doped silicon wafers are mainly divided into two types: P-type and N-type.
[0003] For P-type silicon wafers, the mainstream doping element is B (boron). During the doping process, the B element replaces some of the silicon atoms in the silicon crystal to form holes, thereby making the material positively charged. This doping method can be achieved by directly placing a B dopant in the polysilicon raw material.
[0004] However, the doping of N-type silicon wafers is relatively complex. Since N-type silicon wafers mainly rely on pentavalent elements such as P (phosphorus) and As (arsenic) to provide free electrons, and these elements are extremely volatile at high temperatures, resulting in rapid volatilization of the P element during the doping process, and it is difficult to precisely control the P concentration in the silicon liquid. Currently, to solve this problem, the widely used in the industry is the bell-type gas-phase doping technology. Although this technology can improve the doping uniformity and control accuracy to a certain extent, there is still a problem of low effective utilization rate of doping, that is, a large amount of dopant is not effectively doped into the silicon solution, resulting in waste of raw materials.
[0005] In addition, the P element (such as red phosphorus) used for doping is an ultra-high-purity raw material, and its purity usually reaches above 6N, which is expensive. Therefore, it is necessary to provide an improved technical solution for the above technical problems, which is of great significance for the manufacturing of semiconductor wafers. Summary of the Utility Model
[0006] In view of the defects and deficiencies of the existing de-bonding machine in the above-mentioned prior art, the purpose of this application is to provide a gas-phase heavy doping device to improve the effective utilization rate of doping, reduce production costs, and improve the economic benefits of semiconductor manufacturing.
[0007] This application provides a gas-phase heavy doping device, including a quartz bell jar, the quartz bell jar has an overflow opening, and the overflow opening is disposed opposite to the material to be doped;
[0008] The quartz bell jar sequentially includes a doping cavity and a cartridge placement cavity upward from the overflow opening. At least part of the side wall of the cartridge placement cavity is configured as a second diversion part. The second diversion part is inclined and bent from the side wall of the bell jar of the doping cavity toward the interior of the quartz bell jar, forming a cartridge placement cavity including a frustum structure to reduce the volume of the cartridge placement cavity.
[0009] In some embodiments, all side walls of the cartridge placement cavity are inclined side walls, and the cartridge placement cavity is formed into a cavity with a conical structure.
[0010] In some embodiments, the volume of the doping cavity configured with the second diversion part is reduced by at least 40% compared with the initial doping cavity volume.
[0011] In some embodiments, the second diversion part of the cartridge placement cavity is a planar structure.
[0012] In some embodiments, the second diversion part has several diversion surfaces connected in sequence, and each diversion surface is a planar structure.
[0013] In some embodiments, the inclination angle of the second diversion part in the horizontal direction is between 30° and 75°.
[0014] In some embodiments, in the horizontal direction, there is a minimum distance L between the doped cartridge in the cartridge placement cavity and the second diversion part, and the diameter of the doping cavity is D, where 1 / 18 ≤ L / D ≤ 1 / 6.
[0015] In some embodiments, the height of the quartz bell jar is greater than or equal to 300 mm, and the ratio of the height of the doping cavity to the height of the cartridge placement cavity is greater than or equal to 2.
[0016] In some embodiments, the distance between the overflow opening and the impurity to be doped is d, and 5 mm ≤ d ≤ 30 mm.
[0017] In some embodiments, the heavily doped dopant used in the quartz bell jar is one or several dopants containing phosphorus, arsenic, and antimony elements.
[0018] Compared with the prior art, the technical solution provided by this application has the following beneficial effects:
[0019] In the technical solution of the present application, by improving the structure of the existing gas-phase heavy doping device, especially optimizing the structure of the housing side wall of the material box placement cavity of the quartz bell jar: The quartz bell jar sequentially includes a doping cavity and a material box placement cavity from the overflow opening upwards. At least part of the side wall of the material box placement cavity is configured as a second diversion part. The second diversion part is inclined and bent from the housing side wall of the doping cavity towards the cavity of the quartz bell jar, forming a material box placement cavity including a frustum structure to reduce the volume of the material box placement cavity. This doping device can achieve the purpose of saving dopants and improving doping efficiency. The gas evaporated from the material box chamber directly flows downward along the side wall of the quartz bell jar and enters the doping chamber, approaching the surface of the material to be doped for gas-phase doping, realizing the improvement of the concentration of the dopant-containing mixed gas in the material box chamber, saving the use of dopants, reducing costs, and improving doping efficiency. Description of the Drawings
[0020] Figure 1 is a schematic structural diagram of a gas-phase doping device in the prior art;
[0021] Figure 2 is a fluid simulation diagram of the doping process using the gas-phase doping device in the prior art;
[0022] Figure 3 is a schematic structural diagram of the gas-phase heavy doping device provided in the first embodiment of the present application;
[0023] Figure 4 is a schematic structural diagram of an implementation manner of the second diversion part provided in the first embodiment of the present application;
[0024] Figure 5 is a fluid simulation diagram of the doping process using the gas-phase heavy doping device in the first embodiment of the present application;
[0025] Figure 6 is a schematic structural diagram of the gas-phase heavy doping device provided in the second embodiment of the present application;
[0026] Figure 7 is Figure 6 a schematic structural diagram of an implementation manner of the first diversion part at A in
[0027] Figure 8 is Figure 6 a schematic structural diagram of the second implementation manner of the first diversion part at A in
[0028] Figure 9 is Figure 6 a schematic structural diagram of the third implementation manner of the first diversion part at A in
[0029] Figure 10 is a fluid simulation diagram of the doping process using the gas-phase heavy doping device in the second embodiment of the present application;
[0030] Figure 11 This is a schematic structural diagram of the gas-phase heavily doped doping device provided in Embodiment 3 of the present application.
[0031] Explanation of the reference numerals in the drawings:
[0032] 10. Quartz bell jar; 110. Bell jar side wall; 120. Bell jar top plate; 130. First flow guiding part; 140. Second flow guiding part; 20. Doping material box; 30. Dopant. Detailed implementation manners
[0033] The doping tooling provided by the prior art is as Figure 1 shown. When the silicon material in the quartz crucible is completely melted into silicon liquid, a quartz doping tooling is placed above the liquid surface. The quartz doping tooling includes a doping material box 20 and a quartz bell jar 10. The distance between the doping material box 20 and the silicon liquid is h, and the gap between the bottom of the quartz bell jar 20 and the silicon liquid is D. The dopant red phosphorus (Red Phos, non-toxic, does not spontaneously combust in the atmosphere, catches fire above 400°) placed in the doping material box 20 sublimes and vaporizes at high temperature and fills the quartz bell jar 10. The gas contains a high concentration of P element and diffuses into the silicon liquid on the high-temperature silicon liquid surface. A part of the gas containing a high concentration of phosphorus element overflows through the gap between the quartz bell jar 10 and the silicon liquid. When the phosphorus in the doping material box 20 is completely vaporized or the phosphorus concentration in the silicon liquid reaches the target, the doping tooling is lifted and taken out to complete the gas-phase doping process. After the temperature and the doping concentration of the solution are stable for a certain period of time, the crystal growth process is entered.
[0034] Since the boiling point of the dopant red phosphorus is 725°, and the sublimation and vaporization temperature is between 400° and 700°, while the melting point of silicon is 1415°, during gas-phase doping, the doping material box (made of transparent quartz) containing the dopant red phosphorus is suspended above the upper part of the quartz bell jar, and the bottom of the box is kept at a certain distance from the liquid surface. The quartz bell jar 10 is divided into two areas: the upper material box chamber and the lower gas-phase doping chamber. Figure 2The flow of argon and red phosphorus-containing mixed gas in the doping process is simulated using a thermal fluid CFD software. In the prior art, the gas-phase doping chamber below the doping cartridge 20 consists of a closed-loop gas flow. The mixed gas flows downward along the quartz bell jar 10 into the liquid surface for liquid-phase doping of the liquid surface. At the center of the liquid surface, the mixed gas with reduced red phosphorus concentration rises to the bottom of the cartridge. At the same time, the dopant in the quartz cartridge 20 inside the quartz bell jar 10 vaporizes, evaporates, and diffuses in the cartridge chamber space, and is likely to escape through the gap between the bell jar and the liquid surface. In addition, the mixed gas above the doping cartridge 20 forms multiple closed-loop gas flows, that is, vortices. The high-concentration dopant-containing gas sublimated from the doping cartridge 20 flows through the relatively large-volume cartridge chamber to the gas-phase doping chamber below, and the doping concentration efficiency is relatively low. At a certain dopant sublimation rate, the larger the volume of the cartridge chamber, the more significant the vortices, and the lower the concentration of the dopant-containing mixed gas in the gas-phase doping chamber. Therefore, the utilization rate of the dopant is quite low. In view of the above disadvantages and other disadvantages mentioned in the background art, the present application provides a gas-phase heavy-doping device to reduce the cost of dopant use, shorten the doping time, and improve the doping efficiency.
[0035] The following illustrates the implementation manners of the present application through Examples 1 to 3. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application.
[0036] For ease of description, the opening direction of the quartz bell jar is defined as downward, and the top plate direction of the quartz bell jar is defined as upward.
[0037] Example 1:
[0038] See Figures 3 - 5 , this example provides a gas-phase heavy-doping device, including a quartz bell jar 10, the quartz bell jar 10 having an overflow opening, which is oppositely arranged with respect to the object to be doped; in this example, the object to be doped is silicon liquid, and the heavy dopant is a volatile dopant containing elements such as phosphorus, arsenic, or antimony, and different types of wafers are obtained by gas-phase doping of silicon;
[0039] The quartz bell jar 10 sequentially includes a doping cavity and a cartridge placement cavity upward from the overflow opening. At least part of the side wall of the cartridge placement cavity is configured as a second diversion part 140, and the second diversion part 140 is inclined and bent from the shell side wall 110 of the doping cavity into the cavity of the quartz bell jar 10 to form a cartridge placement cavity including a frustum structure to reduce the volume of the cartridge placement cavity. It can be understood that the doping cavity and the cartridge placement cavity are logical space divisions and not two independent cavity structures. See Figures 3 - 5, in the quartz bell jar 10, the dopant in the dopant cartridge 20 vaporizes, evaporates and diffuses in the space of the cartridge chamber, and then convectively diffuses to the surface of the material to be doped, that is, during the heavy-doping gas-phase doping process above the silicon solution. Due to the reduction of the volume of the quartz bell jar, the diffusion path is shortened, and the required doping time and doping input amount are also correspondingly reduced. In particular, by forming a cartridge placement cavity with a frustum structure, the eddy current phenomenon is improved, thereby improving the doping efficiency of the lower doping cavity.
[0040] In some embodiments, all the side walls of the cartridge placement cavity are inclined side walls, and the cartridge placement cavity is formed into a conical structure cavity, which can further reduce the angle formed between the second diversion part 140 and the cover shell top plate 120, thereby reducing an eddy current area and preventing the doping gas from accumulating in the cartridge placement cavity for a long time, thereby affecting the utilization rate and doping efficiency of the dopant.
[0041] See Figure 3 , in some embodiments, the volume of the doping cavity configured with the second diversion part 140 is reduced by at least 40% compared with the initial doping cavity volume, and the volume of the cartridge placement cavity is reduced, thereby avoiding waste of the dopant and improving the utilization rate and doping efficiency of the dopant. Further, the volume of the doping cavity configured with the second diversion part 140 is reduced by at least 50% compared with the initial doping cavity volume.
[0042] Continue to see Figure 3 , in some embodiments, the second diversion part 140 of the cartridge placement cavity is a planar structure. The wall thickness parameters of the second diversion part 140 and the cover shell side wall 110 can be kept consistent. The inner diversion surface of the planar structure provides a stable air flow guide, and the planar structure is easier to process and dimension control. It can be understood that due to the frustum structure formed by the second diversion part 140, the frustum side wall is not an absolutely planar structure in three-dimensional space. The planar structure here refers to a smooth diversion surface along the air flow direction, rather than a diversion surface with a curvature.
[0043] In some embodiments, the second diversion part 140 has a plurality of sequentially connected diversion surfaces, and each diversion surface is a planar structure, such as Figure 9 shown. The second diversion part structure with multiple diversion surfaces can provide a more stable diversion effect, avoiding problems such as unstable air flow or eddy current loss caused by a sudden change in the diversion direction between the second diversion part 140 and the cover shell side wall 110 or the cover shell top plate 120. It can be understood that the principle of the multi-segment planar diversion surface is similar to that of the single-segment diversion surface. According to different sizes of doping devices, different structures of the second diversion part 140 can be selected to achieve the best diversion effect and at the same time reduce the cavity volume. Or, the multi-segment diversion surfaces can be set in a splicable connection manner to change parameters such as the angle and height difference of the diversion part, so as to adapt to more application scenarios.
[0044] Continue to see Figure 3, in some embodiments, the inclination angle of the second diversion part 140 in the horizontal direction is between 30° and 75°. If the inclination angle is too large, the distance between the doping cartridge 20 and the second diversion part 140 may be too small, which will instead affect the gas flow path of the dopant; if the inclination angle is too small, the volume of the cartridge placement cavity cannot be effectively reduced, and the angle between the second diversion part 140 and the top plate 120 of the cover shell is also likely to cause eddy currents in the doping gas, affecting the utilization rate of the dopant.
[0045] Continue to refer to Figure 3 , in some embodiments, in the horizontal direction, there is a minimum distance L between the doping cartridge 20 in the cartridge placement cavity and the second diversion part 140, and the diameter of the doping cavity is D, where 1 / 18 ≤ L / D ≤ 1 / 6. An appropriate spacing can enable the gas with a high concentration of dopant to effectively flow along the inner wall of the quartz bell jar into the lower doping chamber.
[0046] Continue to refer to Figure 3 , in some embodiments, the height of the quartz bell jar 10 is greater than or equal to 300 mm, and the ratio of the height of the doping cavity to the height of the cartridge placement cavity is greater than or equal to 2. That is, for a quartz bell jar with a specification of 300 mm, the height of the doping cavity should not exceed 100 mm, and can be, for example, 100 mm, 90 mm, 80 mm or 70 mm.
[0047] Continue to refer to Figure 3 , in some embodiments, the distance between the overflow opening and the material to be doped is d, and 5 mm ≤ d ≤ 30 mm. This distance can provide an appropriate gas flow path, improve the doping efficiency, and at the same time form a more stable eddy current seal outside the frustum. As an example, the distance d can be 5 mm, 10 mm, 15 mm, 20 mm or 30 mm.
[0048] Now provide a set of comparative data on the implementation effects of a comparative example and a doping device provided in this embodiment:
[0049] For a quartz bell jar with an outer diameter of 250 mm, a wall thickness of 6 mm, and a height of 350 mm, and a doping cartridge with an outer diameter of 70 mm, a wall thickness of 5 mm, and a height of 40 mm, both are used for pulling 8-inch heavily doped single crystals doped with red phosphorus. Among them, 120 kg of polysilicon is charged, and argon is used as the protective gas.
[0050] In the comparative example, 500 g of red phosphorus was used for gas-phase doping for 30 minutes, and the concentration of red phosphorus in the silicon solution reached 0.1% (1000 ppma). 500 g of red phosphorus was used for gas-phase doping for 30 minutes. For the quartz bell jar with a doping chamber height of 250 mm, a cassette placement chamber of 100 mm, and a frustum shape, where the horizontal distance from the doping cassette to the quartz bell jar was 10 mm, the concentration of red phosphorus in the silicon solution reached 0.1% (1000 ppma). Doping was carried out under the same doping process conditions as in the comparative example for 20 minutes, using 400 g of red phosphorus. The doping time was shortened by 30%, and the consumption of red phosphorus was saved by 20%.
[0051] As can be seen from the above experiments, after using the gas-phase doping device of the technical solution of Example 1, due to the second diversion part optimizing the air flow direction in the cassette placement chamber, reducing the eddy current loss of the mixed air flow forming a closed-loop convection in the cassette chamber, and reducing the volume of the cassette placement chamber, promoting the doped elements to enter the lower doping chamber for effective mixing and doping process, the doping concentration is higher, the material cost is lower, and the doping process is more efficient.
[0052] Example 2:
[0053] See Figures 6 - 10 , this example provides a gas-phase heavy doping device, including a quartz bell jar 10. The quartz bell jar 10 has an overflow opening, which is oppositely arranged with the material to be doped. In this example, the material to be doped is silicon liquid, and the heavy doping agent is a doping agent containing volatile elements such as phosphorus, arsenic or antimony. Different types of wafers are obtained by gas-phase doping of silicon; the quartz bell jar 10 further includes a cover shell top plate 120, which is circular, and the cover shell side wall 110 is perpendicular to the cover shell top plate 120 to form a cavity structure with an overflow opening with the cover shell top plate 120. That is, the quartz bell jar 10 provided in this example is a cylindrical structure;
[0054] The quartz bell jar 10 includes a cover shell side wall 110. One end of the cover shell side wall 110 close to the overflow opening has a first diversion part 130. The first diversion part 130 bends towards the cavity of the quartz bell jar 10 along the cover shell side wall 110 to reduce the opening size of the overflow opening. That is, the area surrounded by the first diversion part 130 is a frustum configuration with a wider top and a narrower bottom. See Figures 6 - 10 , the inclined first diversion part 130 forms a rotating eddy current below the outside of the frustum. This eddy current can achieve gas sealing, making it difficult for the mixed gas containing the doping agent inside the quartz bell jar 10 to flow into or diffuse to the outside of the bell jar. That is, it prolongs the residence time of the doping agent inside the quartz bell jar 10, realizes sufficient and effective doping, and improves the doping efficiency.
[0055] See Figures 6 - 9, in some embodiments, the opening diameter of the overflow opening formed by the first flow guiding portion 130 is reduced by 5% to 15% compared to the opening diameter of the overflow opening formed by the side wall 110 of the housing. As an example, the diameter of the side wall of the quartz clock housing 10 is 250 mm, and the overflow opening diameter after setting the first flow guiding portion 130 can be 212.5 mm, 215 mm, 220 mm, 225 mm, 230 mm or 237.5 mm, all of which can effectively improve the air flow direction.
[0056] Continue to refer to Figures 6 - 9 , in some embodiments, the height difference between the upper and lower ends of the first flow guiding portion 130 is H, that is, the height of the frustum structure is H, where 5 mm ≤ H ≤ 50 mm. The flow guiding structure within this height range can effectively change the air flow direction within the quartz clock housing 10, and at the same time can effectively act as a barrier to the eddy current air flow outside the frustum, thereby achieving a good gas sealing effect at the overflow opening. As an example, the height H can be 5 mm, 10 mm, 20 mm, 40 mm or 50 mm.
[0057] Continue to refer to Figures 6 - 9 , in some embodiments, the flow guiding surface of the first flow guiding portion 130 is a planar structure, as Figure 7 shown in the schematic structure of the first flow guiding portion 130, that is, regardless of the inclination angle of the first flow guiding portion 130, its flow guiding surface is a smooth plane, and the cavity structure surrounded by the flow guiding surface is in a frustum configuration. It can be understood that the structure of the first flow guiding portion 130 is an extended structure of the side wall 110 of the housing, and its wall thickness parameter can remain the same or increase to increase its strength. At this time, the inclination angles of the internal flow guiding surface and the external flow guiding surface of the first flow guiding portion 130 are also the same. The internal flow guiding surface of the planar structure provides a stable air flow guide, and the planar structure is easier to process and dimension control. In an alternative embodiment, refer to Figure 8 , the external flow guiding surface of the first flow guiding portion 130 can also be a flow guiding surface with a concave arc towards the cavity, providing more stable eddy current formation conditions for the eddy current air flow formed outside the frustum, making the eddy current air seal more tight.
[0058] Refer to Figure 9 , in some embodiments, the first flow guiding portion 130 has a plurality of sequentially connected flow guiding surfaces, and each of the flow guiding surfaces is a planar structure. It can be understood that the principle of the multi-segment planar flow guiding surface is similar to that of the single-segment flow guiding surface. According to different sizes of tooling, different structures of the first flow guiding portion 130 can be selected to achieve the best flow guiding effect. Or, the multi-segment flow guiding surfaces can be set in a splicing connection manner to change parameters such as the angle and height difference of the flow guiding portion, so as to adapt to more application scenarios.
[0059] Continue to refer to Figures 6 - 9, in some embodiments, a necking angle α is formed between the first diversion part 130 and the side wall 110 of the cover housing, where 45° ≤ α ≤ 85°. If the necking angle is less than 45°, the diameter of the overflow opening will be reduced, that is, the area of the overflow opening will be reduced, and the contact area between the dopant and the silicon liquid will be reduced, which may cause the adverse effect of reduced doping efficiency. If the necking angle is greater than 85°, it cannot play a good role in changing the gas flow direction and cannot form a good vortex seal. It can be understood that when the quartz bell jar 10 is a cylindrical cavity, in order to achieve a stable diversion effect everywhere in the cavity and a good vortex gas seal effect outside, the necking angle α should remain unchanged. Further, 60° ≤ α ≤ 75° to provide a relatively better diversion effect.
[0060] Continue to refer to Figures 6 - 9 , in some embodiments, the distance between the overflow opening and the material to be doped is d, that is, the distance between the opening and the silicon liquid level is d, where 5mm ≤ d ≤ 30mm. This distance can provide a suitable air flow path, improve the doping efficiency, and at the same time can form a more stable vortex seal outside the frustum. As an example, the distance d can be 5mm, 10mm, 15mm, 20mm or 30mm.
[0061] Continue to refer to Figures 6 - 9 , in some embodiments, the doping cartridge 20 is placed at one end of the quartz bell jar 10 away from the overflow opening inside the quartz bell jar 10, and there is a minimum distance between the doping cartridge 20 and the material to be doped, and this minimum distance is greater than or equal to 2 / 3 of the height of the quartz bell jar 10. As an example, when the selected height is 300mm, this minimum distance is greater than 200mm, for example, it can be 210mm, 220mm, 230mm or 240mm. Otherwise, the doping cartridge 20 is affected by the thermal radiation of the silicon liquid, causing the dopant to rapidly sublime and evaporate completely, resulting in too high a dopant concentration in the quartz bell jar 10 and unstable doping concentration in the silicon liquid. At the same time, it can also enable the dopant 30 in the doping cartridge 20 to have enough gas-phase mixing space to maintain a suitable doping concentration at the silicon liquid surface.
[0062] Now provide a set of comparative data on the implementation effects of a comparative example and a tooling provided by this embodiment: For a quartz bell jar with an outer diameter of 250mm, a wall thickness of 6mm, and a height of 300mm, and all are used for pulling 8-inch heavily doped single crystals doped with red phosphorus. Among them, 120kg of polysilicon is charged, and argon is used as the protective gas.
[0063] In the comparative example, 300 g of red phosphorus was used for vapor doping, and the doping time was 30 minutes. The concentration of red phosphorus in the solution only reached 0.1% (1000 ppma); while for the technical solution with an overflow opening being a frustum-shaped necking (the height of the first diversion part is 20 mm, and the necking angle is 60°), only 220 g of red phosphorus was used for doping for 20 min. On the basis of shortening the doping time by 30%, the concentration of red phosphorus in the solution can reach 0.1% (1000 ppma).
[0064] As can be seen from the above tests, after adopting the vapor doping device provided by the technical solution of Example 2, due to the formation of local eddy currents in the gas below the outer side of the frustum, the eddy currents exist between the mixed gas inside the quartz bell jar and the clean argon gas flow outside the quartz bell jar, which can achieve the effect of gas sealing, prevent the mixed gas from flowing to the clean argon gas flow outside, so the doping concentration is higher, the material cost is lower, and the doping process is more efficient.
[0065] Example 3:
[0066] See Figure 11 , this example also provides a vapor heavy doping device, including a quartz bell jar 10, the quartz bell jar 10 has an overflow opening, and the overflow opening is oppositely arranged to the material to be doped. In this example, the material to be doped is silicon liquid, and the heavy doping agent 30 is a doping agent containing volatile elements such as phosphorus, arsenic or antimony. Different types of wafers are obtained by vapor doping silicon;
[0067] The quartz bell jar 10 successively includes a doping cavity and a material box placement cavity from the overflow opening upwards. At least part of the side wall of the material box placement cavity is configured as a second diversion part 140. The second diversion part 140 is inclined and bent from the side wall 110 of the casing of the doping cavity towards the cavity of the quartz bell jar 10 to form a material box placement cavity including a frustum structure to reduce the volume of the material box placement cavity. It can be understood that the doping cavity and the material box placement cavity are logical spatial divisions, not two independent cavity structures. The quartz bell jar 10 also includes a casing side wall 110, and one end of the casing side wall 110 close to the overflow opening has a first diversion part 130. The first diversion part 130 is bent towards the cavity of the quartz bell jar 10 along the casing side wall 110 to reduce the opening size of the overflow opening, that is, the area surrounded by the first diversion part 130 is a frustum configuration with a wider upper part and a narrower lower part.
[0068] In the doped material box 20 within the quartz bell jar 10, the dopant vaporizes, evaporates, and diffuses within the space of the material box chamber, and then convectively diffuses to the surface of the material to be doped, that is, during the heavy-doped gas-phase doping process above the silicon solution. Due to the reduction in the volume of the quartz bell jar 10, the diffusion path is shortened, and the required doping time and doping input amount are also correspondingly reduced. In particular, by forming a material box placement cavity with a frustum structure, the eddy current phenomenon is improved, thereby enhancing the doping efficiency of the lower doping cavity. Continuing, the inclined first guiding portion 130 forms a rotating eddy current below the outer side of the frustum, and this eddy current can achieve gas sealing, making it difficult for the mixed gas containing the dopant inside the quartz bell jar 10 to flow into or diffuse to the outside of the bell jar. That is to say, the residence time of the dopant inside the quartz bell jar 10 is extended, achieving sufficient and effective doping and improving the doping efficiency.
[0069] The other similarities between this embodiment and the first and second embodiments will not be elaborated here. The technical solution of this application has high industrial utilization value because it effectively overcomes various drawbacks in the prior art.
[0070] The above embodiments merely illustrate the principles and effects of this application by way of example, and are not intended to limit this application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in this application should still be covered by the claims of this application.
Claims
1. A gas phase heavy doping device, comprising a quartz bell jar, wherein the quartz bell jar has an overflow opening, wherein the overflow opening is arranged opposite to the doped substance; characterized in that: The quartz bell jar includes a doping chamber and a material box placement chamber in sequence from the overflow opening upward, and at least a portion of the side wall of the material box placement chamber is configured as a second guide portion, and the second guide portion is inclined and bent from the side wall of the cover shell of the doping chamber toward the cavity of the quartz bell jar to form a material box placement chamber including a frustum structure to reduce the volume of the material box placement chamber.
2. The gas phase heavy doping device according to claim 1, characterized in that: All side walls of the material box placement cavity are inclined side walls, so that the material box placement cavity is formed into a cavity with a conical structure.
3. The gas phase heavy doping device according to claim 1, characterized in that: The volume of the doping cavity configured with the second guide portion is reduced by at least 40% compared with the initial doping cavity volume.
4. The gas phase heavy doping device according to claim 1, characterized in that: The second flow guide portion of the material box placement cavity is a planar structure.
5. The gas phase heavy doping device according to claim 4, characterized in that: The second guide portion has a plurality of guide surfaces connected in sequence, and each guide surface is a planar structure.
6. The gas phase heavy doping device according to claim 1, characterized in that: The inclination angle of the second guide portion in the horizontal direction is between 30° and 75°.
7. The gas phase heavy doping device according to claim 1, characterized in that: In the horizontal direction, the doping material box in the material box placement cavity has a minimum distance L from the second guide portion, and the diameter of the doping cavity is D, wherein 1 / 18≤L / D≤1 / 6.
8. The gas phase heavy doping device according to claim 1, characterized in that: The height of the quartz bell jar is greater than or equal to 300 mm, and the ratio of the height of the doping cavity to the height of the material box placement cavity is greater than or equal to 2.
9. The gas phase heavy doping device according to claim 1, characterized in that: The distance between the overflow opening and the object to be doped is d, 5mm≤d≤30mm.