Gas-phase heavy doping device

Abstract

The utility model provides a gas-phase heavy doping device which comprises a quartz clock cover, the quartz clock cover is provided with an overflow opening, and the overflow opening is arranged opposite to a to-be-doped object; the quartz clock cover comprises a cover shell side wall, a first flow guide part is arranged at the end, close to the overflow opening, of the cover shell side wall, and the first flow guide part is bent towards the interior of the cavity of the quartz clock cover along the cover shell side wall so as to reduce the opening size of the overflow opening. By adopting the doping device, clean protective gas on the outer side of the bell jar is blown to the liquid level from top to bottom, a rotating vortex is formed below the outer side of the frustum, and the vortex can realize gas sealing, so that mixed gas containing dopants on the inner side of the bell jar is difficult to flow into or diffuse to the outer side of the bell jar, the use of the dopants can be effectively reduced, the cost is reduced, and the service life of the bell jar is prolonged. And the doping efficiency is improved.

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 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, for the doping of N-type silicon wafers, the situation 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 manufacture of semiconductor wafers. Utility Model Content

[0006] In view of the defects and deficiencies of the existing deburring machine in the above 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 includes a bell jar side wall, and one end of the bell jar side wall close to the overflow opening has a first guiding portion, and the first guiding portion bends towards the cavity of the quartz bell jar along the bell jar side wall to reduce the opening size of the overflow opening.

[0009] In some embodiments, the opening diameter of the overflow opening formed by the first diversion part is reduced by 5% to 15% compared with the opening diameter of the overflow opening formed by the side wall of the housing.

[0010] In some embodiments, the height difference between the upper and lower ends of the first diversion part is H, and 5 mm ≤ H ≤ 50 mm.

[0011] In some embodiments, the diversion surface of the first diversion part is a planar structure.

[0012] In some embodiments, the first diversion part has several sequentially connected diversion surfaces, and each diversion surface is a planar structure.

[0013] In some embodiments, the first diversion part and the side wall of the housing form a necking angle α, and 45° ≤ α ≤ 85°.

[0014] In some embodiments, the distance between the overflow opening and the impurity to be doped is d, and 5 mm ≤ d ≤ 30 mm.

[0015] In some embodiments, the quartz bell jar further includes a housing top plate, the housing top plate is circular, and the side wall of the housing is perpendicular to the housing top plate to form a cavity structure with an overflow opening with the housing top plate.

[0016] In some embodiments, the doping material box is placed at one end of the quartz bell jar far from the overflow opening, and there is a minimum distance between the doping material box and the impurity to be doped, and this minimum distance is greater than or equal to 2 / 3 of the height of the quartz bell jar.

[0017] In some embodiments, the heavily doped dopant used in the quartz bell jar is a dopant containing one or more of phosphorus, arsenic, and antimony elements.

[0018] Compared with the prior art, the technical solution provided by the present 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 sidewall at the overflow opening of the quartz bell jar: one end of the housing sidewall close to the overflow opening has a first guiding portion, which bends along the housing sidewall into the cavity of the quartz bell jar to reduce the opening size of the overflow opening. A frustum shape design with a gradually decreasing diameter is adopted. When the mixed gas containing dopant inside the bell jar flows to the frustum position, it starts to blow towards the surface of the material to be doped in the central direction, and the clean protective gas outside the bell jar blows downwards towards the liquid surface, forming 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 dopant inside the bell jar to flow into or diffuse to the outside of the bell jar. This device can effectively reduce the use of dopant, lower costs, and improve 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 Figure 3 a schematic structural diagram of one embodiment of the first guiding portion at A in

[0024] Figure 5 is Figure 3 a schematic structural diagram of the second embodiment of the first guiding portion at A in

[0025] Figure 6 is Figure 3 a schematic structural diagram of the third embodiment of the first guiding portion at A in

[0026] Figure 7 is a fluid simulation diagram of the doping process using the gas-phase heavy doping device in the first embodiment of the present application;

[0027] Figure 8 is a schematic structural diagram of the gas-phase heavy doping device provided in the second embodiment of the present application;

[0028] Figure 9 is a schematic structural diagram of one embodiment of the second guiding portion provided in the second embodiment of the present application;

[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 heavy doping device provided in the third embodiment of the present application.

[0031] Explanation of reference numerals:

[0032] 10. Quartz bell jar; 110. Bell jar side wall; 120. Bell jar top plate; 130. First diversion part; 140. Second diversion part; 20. Doping material box; 30. Dopant. Detailed implementation manners

[0033] The doping device 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 device is placed above the liquid surface. The quartz doping device 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 phosphorus 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 removed 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 h from the liquid surface to provide sufficient gas mixing space. The quartz bell jar 10 is divided into two regions: a material box chamber in the upper part and a gas-phase doping chamber in the lower part. Figure 2 The flow diagram of argon and red phosphorus-containing mixed gas during the doping process simulated by the thermal fluid CFD software is shown. It can be seen that the gas-phase doping chamber below the doping material box 20 consists of a closed-loop air flow. The mixed gas flows downward along the quartz bell jar 10 into the liquid surface for liquid-phase doping. At the center part of the liquid surface, the mixed gas with reduced red phosphorus concentration rises to the bottom of the material box. At the same time, the dopant in the quartz material box 20 in the quartz bell jar 10 vaporizes, evaporates and diffuses in the space of the material box chamber, and is likely to escape through the gap between the bell jar and the liquid surface, which prolongs the doping time and increases the doping input amount, affecting the doping efficiency. 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 use cost of the dopant, shorten the doping time and improve the doping efficiency.

[0035] The following describes the implementation manners of the present application through Embodiment 1 to Embodiment 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. 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, it is defined that the opening direction of the quartz bell jar is downward, and the top plate direction of the quartz bell jar is upward.

[0037] Embodiment 1:

[0038] Referring to Figures 3 to 7 , this embodiment provides a vapor-phase heavy doping device, including a quartz bell jar 10. The quartz bell jar 10 has an overflow opening, and this overflow opening is disposed opposite to the dopant to be doped. In this embodiment, the dopant to be doped is silicon liquid, and the heavy doping agent 30 is a volatile doping agent containing elements such as phosphorus, arsenic, or antimony. Different types of wafers are obtained by vapor-phase doping of silicon; the quartz bell jar 10 further includes a bell jar top plate 120, and this bell jar top plate 120 is circular. The bell jar side wall 110 is perpendicular to the bell jar top plate 120 to form a cavity structure with an overflow opening with the bell jar top plate 120. That is, the quartz bell jar 10 provided in this embodiment is a cylindrical structure;

[0039] The quartz bell jar 10 includes a bell jar side wall 110. One end of the bell jar side wall 110 close to the overflow opening has a first guiding portion 130. This first guiding portion 130 bends towards the interior of the cavity of the quartz bell jar 10 along the bell jar side wall 110 to reduce the opening size of the overflow opening. That is, the area surrounded by the first guiding portion 130 is a frustum configuration that is wider at the top and narrower at the bottom. Referring to Figure 3 and Figure 4 , the inclined first guiding portion 130 forms a rotational 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.

[0040] Referring to Figures 3 to 6 , in some implementation manners, the opening diameter of the overflow opening formed by the first guiding portion 130 is reduced by 5% to 15% compared with the opening diameter of the overflow opening formed by the bell jar side wall 110. As an example, the diameter of the bell jar side wall of the quartz bell jar 10 is 250 mm. The overflow opening diameter after setting the first 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.

[0041] Continuing to refer to Figures 3 to 6, 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 bell jar 10, and at the same time can effectively act as a barrier to the eddy 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.

[0042] Continue to refer to Figures 3 to 6 , in some embodiments, the flow guiding surface of the first flow guiding portion 130 is a planar structure, as Figure 4 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 guiding, and the planar structure is more conducive to processing and dimension control. In an alternative embodiment, refer to Figure 5 , 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 formation conditions for the eddy air flow formed outside the frustum. The eddy can better form a stable air flow direction along the arc-shaped external flow guiding surface, making the eddy air seal more tight. It should be noted that due to the frustum structure formed by the first flow guiding portion 130, the frustum side wall is not an absolutely planar structure in three-dimensional space. Here, the planar structure refers to a smooth flow guiding surface along the air flow direction, rather than a flow guiding surface with a curvature.

[0043] Refer to Figure 6 , in some embodiments, the first flow guiding portion 130 has several sequentially connected flow guiding surfaces, and each of the flow guiding surfaces is a planar structure. It can be understood that the principle of multiple planar flow guiding surfaces is similar to that of a single flow guiding surface. According to doping devices of different sizes, the first flow guiding portion 130 with different structures can be selected to achieve the best flow guiding effect. Or, the multiple flow guiding surfaces can be set in a splicable 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.

[0044] Continue to refer to Figures 3 to 6, in some embodiments, the first diversion part 130 and the side wall 110 of the bell cover form a necking angle α, 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, nor can it form a good vortex seal. It can be understood that when the quartz bell cover 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.

[0045] Continue to refer to Figures 3 to 6 , in some embodiments, the distance between the overflow opening and the dopant 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 gas flow path, improve the doping efficiency, and at the same time form a more stable vortex seal outside the frustum. As an example, the distance d can be 5mm, 10mm, 15mm, 20mm or 30mm.

[0046] Continue to refer to Figures 3 to 6 , in some embodiments, the doping cartridge 20 is placed at one end of the quartz bell cover 10 away from the overflow opening, and there is a minimum distance h between the doping cartridge 20 and the dopant to be doped, and this minimum distance is greater than or equal to 2 / 3 of the height of the quartz bell cover 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 sublimate and evaporate rapidly, resulting in too high a dopant concentration in the quartz bell cover 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.

[0047] Now provide a set of comparative data on the implementation effects of a comparative example and a doping device provided in this embodiment: For a quartz bell cover 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.

[0048] In the comparative example, 300 g of red phosphorus was used for gas-phase 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 20 min of doping. On the basis of shortening the doping time by 30%, the concentration of red phosphorus in the solution reached 0.1% (1000 ppma).

[0049] As can be seen from the above tests, after using the gas-phase doping device of the technical solution of Example 1, 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.

[0050] Example 2:

[0051] See Figures 8 to 10 , this embodiment provides a gas-phase 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 embodiment, 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 elements, and different types of wafers are obtained by gas-phase doping of silicon;

[0052] The quartz bell jar 10 successively includes a doping cavity and a material box placement cavity upward from the overflow opening. At least part of the side wall of the material box placement cavity is configured as a second diversion part 140, and the second diversion part 140 is inclined and bent from the side wall 110 of the shell of the doping cavity toward 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 space divisions, not two independent cavity structures. See Figures 8 to 10 , in the process of gas-phase heavy doping where the doping agent in the doping material box 20 in the quartz bell jar 10 vaporizes and diffuses in the material box chamber space and then convectively diffuses to the surface of the material to be doped, that is, above the silicon solution, due to the reduction of 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. Especially, forming a material box placement cavity with a frustum structure improves the eddy current loss phenomenon, and thus improves the doping efficiency of the lower doping cavity.

[0053] In some embodiments, all the side walls of the material box placement cavity are inclined side walls, and the material box placement cavity is formed into a conical cavity structure, which can further reduce the included angle formed between the second diversion part 140 and the top plate 120 of the shell, and thus reduce an eddy current area, avoid the long-term accumulation of doping gas in the material box placement cavity, and thus affect the utilization rate and doping efficiency of the doping agent.

[0054] See Figure 8 , in some embodiments, the volume of the doping cavity of the second flow guiding portion 140 is reduced by at least 40% compared to the initial doping cavity volume, reducing the volume of the cassette placement cavity, thereby avoiding waste of dopants and improving the utilization rate and doping efficiency of the dopants. Further, the volume of the doping cavity of the second flow guiding portion 140 is reduced by at least 50% compared to the initial doping cavity volume.

[0055] Continue to refer to Figure 8 , in some embodiments, the second flow guiding portion 140 of the cassette placement cavity is a planar structure. The wall thickness parameters of the second flow guiding portion 140 and the side wall 110 of the housing can be kept consistent. The inner flow guiding surface of the planar structure provides a stable air flow guidance, and the planar structure is easier to process and control dimensions. It can be understood that due to the frustum structure formed by the second flow guiding portion 140, the side wall of the frustum is not an absolutely planar structure in three-dimensional space. The planar structure here refers to a smooth flow guiding surface along the air flow direction, rather than a flow guiding surface with a curvature.

[0056] In some embodiments, the second flow guiding portion 140 has a plurality of sequentially connected flow guiding surfaces, and each flow guiding surface is a planar structure as Figure 9 shown. The second flow guiding portion structure with multiple flow guiding surfaces can provide a more stable flow guiding effect, avoiding problems such as unstable air flow or formation of eddy current loss caused by a sudden change in the flow guiding direction between the second flow guiding portion 140 and the side wall 110 or the top plate 120 of the housing. It can be understood that the principle of the multiple planar flow guiding surfaces is similar to that of the single flow guiding surface. According to doping devices of different sizes, different structures of the second flow guiding portion 140 can be selected to achieve the best flow guiding effect and at the same time reduce the cavity volume. Or, the multiple flow guiding surfaces are arranged in a spliceable 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.

[0057] Continue to refer to Figure 8 , in some embodiments, the inclination angle of the second flow guiding portion 140 in the horizontal direction is between 30° and 75°. If the inclination angle is too large, the distance between the doping cassette 20 and the second flow guiding portion 140 may be too small, which may instead affect the air flow path of the dopant. If the inclination angle is too small, the volume of the cassette placement cavity cannot be effectively reduced, and the angle between the second flow guiding portion 140 and the top plate 120 of the housing is also likely to cause eddy currents in the doping gas, affecting the utilization rate of the dopant.

[0058] Continue to refer to Figure 8, in some embodiments, in the horizontal direction, there is a minimum distance L between the doping cassette 20 in the cassette 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 below.

[0059] Continue to refer to Figure 8 , 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 cassette 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 for example, it can be 100 mm, 90 mm, 80 mm or 70 mm.

[0060] Continue to refer to Figure 8 , in some embodiments, the distance between the overflow opening and the dopant to be doped is d, and 5 mm ≤ d ≤ 30 mm. This distance can provide an appropriate air flow path, improve the doping efficiency, and at the same time form a more stable vortex seal outside the frustum. As an example, the distance d can be 5 mm, 10 mm, 15 mm, 20 mm or 30 mm.

[0061] Now provide a set of comparative data on the implementation effects of a comparative example and a doping device provided in this embodiment:

[0062] 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 cassette 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.

[0063] In the comparative example, 500 g of red phosphorus was used for gas-phase doping, and the doping time was 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, and the doping time was 30 minutes; while for a quartz bell jar with a frustum shape, with a doping cavity height of 250 mm and a cassette placement cavity of 100 mm, where the horizontal distance from the doping cassette to the quartz bell jar is 10 mm, the concentration of red phosphorus in the silicon solution also reached 0.1% (1000 ppma). Doping was carried out under the same doping process conditions as in the comparative example, with a doping time of 20 minutes, 400 g of red phosphorus was used, the doping time was shortened by 30%, and the red phosphorus usage was saved by 20%.

[0064] As can be seen from the above tests, after adopting the gas-phase doping device provided by the technical solution of the second embodiment, since the second diversion part optimizes the air flow direction in the cartridge placement cavity, reduces the eddy current loss of the mixed air flow forming a closed-loop convection in the cartridge chamber, and reduces the volume of the cartridge placement cavity, promoting the doping elements to enter the lower doping cavity for effective mixing and doping process, the doping concentration is higher, the material cost is lower, and the doping process is more efficient.

[0065] Embodiment Three:

[0066] Refer to Figure 11 , this embodiment also 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 to the material to be doped. In this embodiment, the material to be doped is silicon liquid, and the heavy doping agent 30 is a volatile doping agent containing elements such as phosphorus, arsenic or antimony. Different types of wafers are obtained by gas-phase doping of silicon;

[0067] The quartz bell jar 10 successively includes a doping cavity and a cartridge placement cavity from the overflow opening upwards. At least part of the side wall of the cartridge 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 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, not two independent cavity structures. The quartz bell jar 10 further includes a side wall 110 of the casing. One end of the side wall 110 of the casing 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 side wall 110 of the casing 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] The doping agent in the doping cartridge 20 in the quartz bell jar 10 vaporizes, evaporates and diffuses in the cartridge chamber space, and then convectively diffuses to the surface of the material to be doped, that is, in the heavy doping gas-phase doping process above the silicon solution. Since the volume of the quartz bell jar 10 is reduced, the diffusion path is shortened, and the required doping time and doping input amount are also correspondingly reduced. Especially, a cartridge placement cavity with a frustum structure is formed, which improves the eddy current phenomenon, and further improves the doping efficiency of the lower doping cavity. Continuing, 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, the residence time of the doping agent inside the quartz bell jar 10 is prolonged to achieve sufficient and effective doping and improve the doping efficiency.

[0069] The other similarities between this embodiment and Embodiment One and Embodiment Two will not be elaborated here. The technical solution of this application has high industrial utilization value because it effectively overcomes various shortcomings in the prior art.

[0070] The above embodiments are only illustrative of the principles and effects of the present application and are not intended to limit the present application. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present application should still be covered by the claims of the present 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 comprises a casing side wall, and one end of the casing side wall close to the overflow opening has a first guide portion, and the first guide portion is bent along the casing side wall into the cavity of the quartz bell jar to reduce the opening size of the overflow opening.

2. The gas phase heavy doping device according to claim 1, characterized in that: The opening diameter of the overflow opening formed by the first guide portion is 5% to 15% smaller than the opening diameter of the overflow opening formed by the side wall of the housing.

3. The gas phase heavy doping device according to claim 1, characterized in that: A height difference between the upper and lower ends of the first guide portion is H, 5mm≤H≤50mm.

4. The gas phase heavy doping device according to claim 1, characterized in that: The guide surface of the first guide portion is a planar structure.

5. The gas phase heavy doping device according to claim 4, characterized in that: The first 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 4, characterized in that: The first air guide portion and the side wall of the housing form a necking angle α, 45°≤α≤85°.

7. 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.

8. The gas phase heavy doping device according to claim 1, characterized in that: The quartz bell jar further comprises a casing top plate, which is circular, and the casing side wall is perpendicular to the casing top plate to form a cavity structure with an overflow opening together with the casing top plate.

9. The gas phase heavy doping device according to claim 1, characterized in that: The doping material box is placed in the quartz bell jar at one end away from the overflow opening, and there is a minimum distance between the doping material box and the object to be doped, and the minimum distance is greater than or equal to 2 / 3 of the height of the quartz bell jar.

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