Method for reducing heavily doped ultra-low resistance leading and discharging times
By performing oxidation treatment and temperature testing steps after the doping step, we ensure that the impurities are evenly distributed in the molten soup, solving the problem of impurities accumulation in heavy-doped ultra-low resistance silicon wafers, reducing the failure rate of shoulder release and production costs.
Patent Information
- Application Number
- CN202411353496.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2024-12-17
AI Technical Summary
During the doping process of heavily doped ultra-low resistance silicon wafers, due to the high concentration of dopant, impurities accumulate on the upper part of the molten soup, resulting in slip dislocation of single crystals and broken bracts on the shoulder crystalline, thereby increasing shoulder release failure rate.
After the doping step is completed, the impurities are evenly distributed in the molten soup by oxidizing treatment at a predetermined crucible speed, argon flow rate, and furnace pressure, including one or more oxidation treatments, followed by a temperature test step to improve the molten soup Convection reduces dopant volatility and improves impurity distribution uniformity.
It reduces the failure rate of shoulder release, shortens the running time of heavy doping ultra-low resistance, reduces the number of replenishment times, and effectively saves production costs.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of heavily-doped single crystal pulling methods, and in particular relates to a method for reducing the number of heavily-doped ultra-low resistance lead-in times. Background Art
[0002] With the development of the semiconductor industry, the demand for ultra-low resistance heavily phosphorus-doped and heavily arsenic-doped silicon wafers for low and medium voltage MOSFET devices is increasing. Along with the incorporation of a large amount of dopants in ultra-low resistance, the doping ratio increases. During the doping process, after the dopant solid is completely sublimated through the bell jar, the isolation valve is opened to extract the bell jar. After testing the temperature for 1-2 hours, the process operations of seeding, shouldering and shoulder rotation are started. The sublimated dopant is brought into the upper surface of the melt by the gas flow in the furnace. However, due to the high concentration of the dopant, the complex convection in the melt cannot bring the dopant into the melt, resulting in a large amount of impurities in the ultra-low resistance being doped and accumulated on the upper part of the melt. After entering the shouldering process, with the process of lattice accumulation, the uneven distribution of impurity concentration causes the occurrence of single crystal slip dislocations, and finally the shoulder crystal line breaks, resulting in shouldering NG. Summary of the invention
[0003] In view of this, the present invention provides a method for reducing the number of heavily-doped ultra-low resistance discharges.
[0004] The technical solution adopted by the present invention to solve its technical problem is: A method for reducing the number of heavily doped ultra-low resistance releases, comprising a doping step, an oxidation step, and a temperature test step performed in sequence, wherein the oxidation step is specifically: after the doping step is completed, oxidation is performed at a predetermined crucible speed, a predetermined argon flow rate, and a predetermined furnace pressure for a predetermined time to make impurities evenly distributed in the molten metal, thereby reducing the shoulder release NG rate.
[0005] Preferably, the oxidation step includes a first oxidation treatment and a second oxidation treatment; The first oxidation treatment specifically comprises: after the doping step is completed, oxidation for a first predetermined time at a first predetermined crucible speed, a first predetermined argon gas flow rate, and a first predetermined furnace pressure; The second oxidation treatment specifically includes: after the first oxidation treatment is completed, oxidation is performed at a second predetermined crucible speed, a second predetermined argon gas flow rate, and a second predetermined furnace pressure for a second predetermined time.
[0006] Preferably, the first predetermined crucible rotation speed is 0.5-1.5 rpm, the first predetermined argon gas flow rate is 60-100 slm, the first predetermined furnace pressure is 11-15 KPa, and the first predetermined time is 20-40 min.
[0007] Preferably, the second predetermined crucible rotation speed is 6-10 rpm, the second predetermined argon gas flow rate is 60-100 slm, the second predetermined furnace pressure is 6-10 KPa, and the second predetermined time is 40-70 min.
[0008] Preferably, the crystal rod does not rotate during the first oxidation treatment and the second oxidation treatment.
[0009] Preferably, the temperature testing time in the temperature testing step is 1-2 hours.
[0010] Preferably, in the temperature testing step, the crucible rotation speed is 10-14 rpm, and the crystal rod rotation speed is 10-30 rpm.
[0011] Preferably, in the temperature testing step, the furnace pressure is 11-15 Kpa, and the argon flow rate is 80-120 slm.
[0012] Preferably, in the doping step, the dopant is one of phosphorus, arsenic and antimony.
[0013] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for reducing the number of times of heavily doped ultra-low resistance release, comprising a doping step, an oxidation step, and a temperature test step performed in sequence, wherein an oxidation step is added between the doping step and the temperature test step, and after the doping is completed, oxidation is performed for a predetermined time at a predetermined crucible speed, a predetermined argon flow rate, and a predetermined furnace pressure. On the one hand, the volatilization amount of the dopant is minimized and the dopant enters the surface of the melt to the maximum extent, thereby ensuring the resistivity requirement; on the other hand, the convection of the melt is improved, so that the dopant on the upper surface of the melt can be fully "stirred" after entering the melt, and the impurities are evenly distributed in the melt, thereby reducing the shoulder release NG rate. DETAILED DESCRIPTION
[0014] The technical solutions and technical effects of the embodiments of the present invention are further elaborated in detail below in combination with the present invention.
[0015] A method for reducing the number of heavily doped ultra-low resistance releases, comprising a doping step, an oxidation step, and a temperature test step performed in sequence, wherein the oxidation step is specifically: after the doping step is completed, oxidation is performed at a predetermined crucible speed, a predetermined argon flow rate, and a predetermined furnace pressure for a predetermined time to make impurities evenly distributed in the molten metal, thereby reducing the shoulder release NG rate.
[0016] Specifically, ultra-low resistance refers to a doping concentration greater than a limit value.
[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for reducing the number of times of heavy-doped ultra-low resistance release, comprising a doping step, an oxidation step, and a temperature test step performed in sequence, wherein an oxidation step is added between the doping step and the temperature test step, and after the doping is completed, oxidation is performed for a predetermined time at a predetermined crucible speed, a predetermined argon flow rate, and a predetermined furnace pressure. On the one hand, the volatilization amount of the dopant is minimized, and the dopant enters the surface of the melt to the greatest extent, thereby ensuring the resistivity requirement; on the other hand, the convection of the melt is improved, so that the dopant on the upper surface of the melt can be fully "stirred" after entering the melt, and the impurities are evenly distributed in the melt, so that the shoulder release NG rate is reduced, the operating time of the heavy-doped ultra-low resistance is shortened, the number of supplementary doping is reduced, and the production cost is effectively saved.
[0018] Furthermore, the oxidation step includes a first oxidation treatment and a second oxidation treatment; The first oxidation treatment specifically includes: after the doping step is completed, oxidation is performed at a first predetermined crucible speed, a first predetermined argon gas flow rate, and a first predetermined furnace pressure for a first predetermined time to reduce volatilization of the dopant.
[0019] The second oxidation treatment specifically includes: after the first oxidation treatment is completed, oxidation is performed at a second predetermined crucible speed, a second predetermined argon gas flow rate, and a second predetermined furnace pressure for a second predetermined time to make the dopant evenly distributed.
[0020] Furthermore, the first predetermined crucible rotation speed is 0.5-1.5 rpm, the first predetermined argon flow rate is 60-100 slm, the first predetermined furnace pressure is 11-15 Kpa, and the first predetermined time is 20-40 min. If the relevant parameters are too large, the dopant will volatilize too much and the resistivity will not meet the requirements.
[0021] Furthermore, the second predetermined crucible speed is 6-10 rpm, the second predetermined argon flow rate is 60-100 slm, the second predetermined furnace pressure is 6-10 KPa, and the second predetermined time is 40-70 min, so as to prevent the volatilization of the dopant under the premise that the dopant is evenly dispersed.
[0022] Furthermore, the crystal rod is not rotated during the first oxidation treatment and the second oxidation treatment. Furthermore, the temperature testing time in the temperature testing step is 1-2 hours.
[0023] Furthermore, in the temperature test step, the crucible speed is 10-14 rpm, and the crystal rod speed is 10-30 rpm. Furthermore, in the temperature test step, the furnace pressure is 11-15 Kpa, and the argon flow rate is 80-120 slm.
[0024] Furthermore, in the doping step, the dopant is one of phosphorus, arsenic and antimony.
[0025] The use of the present invention is described by the following examples. Embodiment 1:
[0026] Adopt 2408 single crystal furnace, 22-inch thermal field growth 8-inch <100> Heavy phosphorus-doped single crystal, feed amount 80kg, doping amount 950g (resistivity range ≤0.001Ω·cm), doping ratio 11.88, red phosphorus solid sublimates through the bell jar and is brought to the upper surface of the molten soup by the gas flow in the furnace. The sublimation time of the dopant is generally 5-8 minutes. When the dopant is completely sublimated, the isolation valve is opened to extract the bell jar, and then oxidation treatment is carried out. The first oxidation treatment is specifically as follows: after the doping step is completed, the crucible speed is 1rpm, the crystal rotation is 0, the argon flow rate is 80slm, the furnace pressure is 13Kpa, and the oxidation 30min; the second oxidation treatment is specifically as follows: after the doping step is completed, the crucible speed is 8rpm, the crystal rotation is 0, the argon flow rate is 80slm, the furnace pressure is 8Kpa, and oxidation is performed for 30min; then a temperature test step is performed, and the temperature test step is specifically as follows: the crucible speed is 12rpm, the crystal rotation is 20rpm, the argon flow rate is 100slm, and the furnace pressure is 13Kpa. After 1-2h of temperature test, crystal induction, shoulder release, shoulder rotation, equal diameter, and tailing are started to obtain a crystal rod. The above method is used for experiments 3 times, and the experimental results are shown in Table 1.
[0027] Table 1 Embodiment 2:
[0028] Adopt 2408 single crystal furnace, 22-inch thermal field growth 8-inch <100> Heavy phosphorus-doped single crystal, feed amount 80kg, doping amount 950g (resistivity range ≤0.001Ω·cm), doping ratio 11.88, red phosphorus solid sublimates through the bell jar and is brought to the upper surface of the molten soup by the gas flow in the furnace. The sublimation time of the dopant is generally 5-8 minutes. When the dopant is completely sublimated, the isolation valve is opened to extract the bell jar, and then oxidation treatment is carried out. The first oxidation treatment is specifically as follows: after the doping step is completed, the crucible speed is 1rpm, the crystal rotation is 0, the argon flow rate is 80slm, the furnace pressure is 13Kpa, and the oxidation 30min; the second oxidation treatment is specifically as follows: after the doping step is completed, the crucible speed is 8rpm, the crystal rotation is 0, the argon flow rate is 80slm, the furnace pressure is 8Kpa, and the oxidation is 60min; then a temperature test step is performed, and the temperature test step is specifically as follows: the crucible speed is 12rpm, the crystal rotation is 20rpm, the argon flow rate is 100slm, and the furnace pressure is 13Kpa. After 1-2h of temperature test, crystal induction, shoulder release, shoulder rotation, equal diameter, and tailing are started to obtain a crystal rod. The above method is used for experiments 3 times, and the experimental results are shown in Table 2.
[0029] Table 2
[0030] Comparative Example 1: Adopt 2408 single crystal furnace, 22-inch thermal field growth 8-inch <100> Heavily doped phosphorus single crystal, feed amount 80kg, doping amount 950g (resistivity range ≤0.001Ω·cm), doping ratio 11.88, red phosphorus solid sublimates through the bell jar and is brought to the upper surface of the molten soup by the gas flow in the furnace, the dopant sublimation time is generally 5-8 minutes, when the dopant is completely sublimated, the isolation valve is opened to extract the bell jar, and then the temperature test step is carried out. The temperature test step is specifically as follows: the crucible speed is 12rpm, the crystal rotation is 20rpm, the argon flow rate is 100slm, and the furnace pressure is 13Kpa. After 1-2h of temperature test, the crystal seeding, shoulder release, shoulder rotation, equal diameter, and tailing are started to obtain the crystal rod. The above method is used for 5 experiments, and the experimental results are shown in Table 3.
[0031] Table 3
[0032] Comparative Example 2: Adopt 2408 single crystal furnace, 22-inch thermal field growth 8-inch <100> Heavily doped phosphorus single crystal, feed amount 80kg, doping amount 950g (resistivity range ≤0.001Ω·cm), doping ratio 11.88, red phosphorus solid sublimates through the bell jar and is brought into the upper surface of the molten soup by the gas flow in the furnace, the sublimation time of the dopant is generally 5-8 minutes, when the dopant is completely sublimated, the isolation valve is opened to extract the bell jar, and then an oxidation treatment is performed, the oxidation treatment is specifically as follows: after the doping step is completed, the crucible speed is 8rpm, the crystal rotation is 0, the argon flow rate is 80slm, the furnace pressure is 13Kpa, and the oxidation is 60min; then a temperature test step is performed, the temperature test step is specifically as follows: the crucible speed is 12rpm, the crystal rotation is 20rpm, the argon flow rate is 100slm, the furnace pressure is 13Kpa, and after 1-2h of temperature test, crystal seeding, shoulder release, shoulder rotation, equal diameter, and tailing are started to obtain a crystal rod. The above method is used for experiments 3 times, and the resistivity of the heads of the three crystal rods pulled out is high, and the ultra-low resistance value cannot be achieved, which does not meet the requirements.
[0033] By comparing Examples 1 and 2 with Comparative Examples 1 and 2, it can be seen that by performing two consecutive oxidation treatments, the number of lead-in times is reduced, the shoulder NG rate is reduced, the operating time of the heavily doped ultra-low resistance is shortened, the number of supplementary doping times is reduced, and the cost is effectively reduced.
[0034] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.
Claims
1. A method for reducing the number of times of heavy-doped ultra-low resistance discharge, characterized in that: The method comprises a doping step, an oxidation step and a temperature test step which are performed in sequence. Specifically, the oxidation step comprises: after the doping step, oxidation is performed for a predetermined time at a predetermined crucible speed, a predetermined argon flow rate and a predetermined furnace pressure so that impurities are evenly distributed in the molten metal, thereby reducing the shoulder release NG rate.
2. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 1, characterized in that: The oxidation step includes a first oxidation treatment and a second oxidation treatment; The first oxidation treatment specifically comprises: after the doping step is completed, oxidation for a first predetermined time at a first predetermined crucible speed, a first predetermined argon gas flow rate, and a first predetermined furnace pressure; The second oxidation treatment specifically includes: after the first oxidation treatment is completed, oxidation is performed at a second predetermined crucible speed, a second predetermined argon gas flow rate, and a second predetermined furnace pressure for a second predetermined time.
3. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 2, characterized in that: The first predetermined crucible rotation speed is 0.5-1.5 rpm, the first predetermined argon gas flow rate is 60-100 slm, the first predetermined furnace pressure is 11-15 Kpa, and the first predetermined time is 20-40 min.
4. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 2, characterized in that: The second predetermined crucible rotation speed is 6-10 rpm, the second predetermined argon gas flow rate is 60-100 slm, the second predetermined furnace pressure is 6-10 Kpa, and the second predetermined time is 40-70 min.
5. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 2, characterized in that: The crystal rod does not rotate during the first oxidation treatment and the second oxidation treatment.
6. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 1, characterized in that: The temperature testing time in the temperature testing step is 1-2h.
7. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 1, characterized in that: In the temperature testing step, the crucible rotation speed is 10-14 rpm, and the crystal rod rotation speed is 10-30 rpm.
8. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 1, characterized in that: In the temperature test step, the furnace pressure is 11-15 Kpa, and the argon flow rate is 80-120 slm.
9. The method for reducing the number of heavily doped ultra-low resistance discharges according to claim 1, characterized in that: In the doping step, the dopant is one of phosphorus, arsenic and antimony.