Method for controlling ratio of hydrogen to trichlorosilane in polycrystalline silicon production

Abstract

The invention relates to the technical field of polycrystalline silicon material preparation, in particular to a method for controlling the ratio of hydrogen to trichlorosilane in polycrystalline silicon production. The method comprises the following steps: determining an ideal power curve and an ideal hydrogen flow curve in an operation period of the reduction furnace by utilizing accumulated data; measuring the actual power PV of the silicon rod at the time Ti, comparing the actual power PV with the ideal power SV corresponding to the time Ti on the ideal power curve, and adjusting the output hydrogen gas inflow MV through PID; adjusting the current frequency value to enable the temperature of the silicon rod to be within a required control range; and the feeding amount of trichlorosilane is automatically adjusted according to the operation time. The method has the advantages that the control method is simple, effective and rapid. And the control is accurate. Consumption is reduced, and silicon rod quality is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polysilicon material preparation, and particularly to a method for controlling the ratio of hydrogen to trichlorosilane in polysilicon production. Background Art

[0002] The main production technologies for industrial production of polysilicon are the improved Siemens method and the silane method. The process of producing polysilicon by the improved Siemens method is as follows: Trichlorosilane and hydrogen are introduced into a reduction furnace, and a vapor deposition reaction occurs on a silicon core at 1000 - 1100 °C to grow into a polysilicon rod. The entire production process is completed by the operation of a distributed control system (DCS) and on-site operation. The DCS operation performs the control of material and electrical parameters, and the on-site operation is mainly the manual control of hand valves, inspections, etc. by workers. During the entire operation cycle of the reduction furnace, the temperature of the silicon core is mainly controlled by current, and the power supply method is mainly constant current variable voltage control.

[0003] During the production process, it is necessary for operators to adjust the flow rates of hydrogen and trichlorosilane and the frequency of the current in combination with automated control, and it is also necessary for workers to regularly observe whether the conditions inside the reduction furnace are appropriate. When the operating conditions such as the material components change, if the DCS operator fails to detect it in time, the on-site inspection personnel need to observe the operating conditions inside the reduction furnace. There are problems such as relying on manual operation and manual experience, inaccurate control, and unstable product quality. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for controlling the ratio of hydrogen to trichlorosilane in polysilicon production, which has rapid adjustment, accurate control, increased single-furnace output, reduced consumption, reduced output of abnormal materials, and improved quality of silicon rods.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows.

[0006] A method for controlling the ratio of hydrogen to trichlorosilane in polysilicon production, the method comprising:

[0007] Using the accumulated data, determining the ideal power curve and the ideal hydrogen flow curve within the operation cycle of the reduction furnace;

[0008] Measuring the actual power P of the silicon rod at time T i and comparing it with the ideal power S corresponding to the time T V on the ideal power curve, and outputting the hydrogen intake M i through PID adjustment; V V V ;

[0009] Adjusting the current frequency value to keep the temperature of the silicon rod within the required control range;

[0010] The trichlorosilane feed rate is automatically adjusted according to the running time.

[0011] Furthermore, the output M is adjusted by PID V The specific method is:

[0012] According to the formula ΔV=P V -S V Calculate at time T i The ideal power value S corresponding to the ideal power curve V The actual power P V The difference ΔV;

[0013] Adjust the hydrogen intake volume so that -20KW≤ΔV≤20KW.

[0014] Furthermore, if ΔV<-20KW, the hydrogen intake volume increases by 2~3Kg / h.

[0015] Furthermore, if ΔV>20KW, the hydrogen intake amount is reduced by 2-3Kg / h.

[0016] Furthermore, the current frequency adjustment method is as follows: the reduction furnace is divided into several stages in the operation cycle, and when the actual temperature and the required ideal temperature deviate when the reduction furnace runs to a certain stage, the current frequency is adjusted to make the silicon rod temperature within the required control range.

[0017] Furthermore, the method for adjusting the trichlorosilane feed rate is as follows: the trichlorosilane feed rate is increased by 2.5 to 3.75 kg / min per hour until the maximum amount is added.

[0018] The present invention provides a method for controlling the ratio of hydrogen and trichlorosilane in polysilicon production, which uses the accumulated reduction furnace operation data to determine the ideal power curve and the ideal hydrogen flow curve within the reduction furnace operation cycle; and measures the silicon rod at time T. i The actual power P V and with the time T i The ideal power S corresponding to the ideal power curve V By contrast, the output hydrogen intake volume M is adjusted by PID V ; Adjust the current frequency value so that the silicon rod temperature is within the required control range; the trichlorosilane feed amount is automatically adjusted according to the running time, thereby ensuring accurate control of the ratio of hydrogen and trichlorosilane in the entire production process of the reduction furnace. Then, accurate control of the polysilicon reduction furnace is achieved. Using the control method provided by the present invention, the growth rate and density of polysilicon rods can be controlled.

[0019] A control method for the ratio of hydrogen to trichlorosilane in polysilicon production provided by the present invention can set a power curve according to the accumulated operation data of the reduction furnace, obtain the optimal ratio of hydrogen to trichlorosilane, so as to increase the single-furnace output of polysilicon in the reduction furnace, reduce consumption, and reduce the output of abnormal materials.

[0020] Compared with the prior art, the advantages of a control method for the ratio of hydrogen to trichlorosilane in polysilicon production provided by the present invention are as follows:

[0021] (1) The control method is simple, effective and rapid.

[0022] (2) The control is precise.

[0023] (3) Reduce consumption and improve the quality of silicon rods. Description of the Drawings

[0024] Figure 1 It is a schematic flow chart of a control method for the ratio of hydrogen to trichlorosilane in polysilicon production provided by the present invention.

[0025] Figure 2 It is a schematic diagram of the control principle for the ratio of hydrogen to trichlorosilane in polysilicon production provided by the present invention. Detailed Embodiments

[0026] To enable those skilled in the art to better understand the technical solutions of the present invention, the following embodiments further describe the present invention in detail. The following embodiments are only used to illustrate the invention, but not to limit the scope of the present invention.

[0027] A control method for the ratio of hydrogen to trichlorosilane in polysilicon production, the method includes:

[0028] Using the accumulated data, determine the ideal power curve and the ideal hydrogen flow curve within the operation cycle of the reduction furnace;

[0029] Measure the actual power P of the silicon rod at time T i and compare it with the ideal power S corresponding to this time T V on the ideal power curve, and adjust the hydrogen intake M i by PID regulation output; V ; V

[0030] Adjust the current frequency value to keep the temperature of the silicon rod within the required control range;

[0031] The feed rate of trichlorosilane is automatically adjusted according to the running time.

[0032] Further, the specific method for adjusting the output M V by PID regulation is: ​

[0033] According to the formula ΔV = P V - S V calculate the ideal power value S corresponding to the ideal power curve at time T i V V and the actual power P i of the difference ΔV;

[0034] Adjust the hydrogen intake so that - 20KW ≤ ΔV ≤ 20KW.

[0035] Further, if ΔV < - 20KW, the hydrogen intake is increased by 2 - 3 Kg / h.

[0036] Further, if ΔV > 20KW, the hydrogen intake is decreased by 2 - 3 Kg / h.

[0037] Further, the adjustment method of the current frequency is as follows: The reduction furnace is divided into several stages during the operation cycle. When the actual temperature and the required ideal temperature deviate when the reduction furnace runs to a certain stage, adjust the current frequency to make the temperature of the silicon rod within the required control range.

[0038] Further, the adjustment method of the trichlorosilane feed rate is as follows: The trichlorosilane intake is increased by 2.5 - 3.75 Kg / min until the maximum amount is reached.

[0039] Example 1

[0040] Combined with Figures 1-2 shown, a control method for the ratio of hydrogen and trichlorosilane in polysilicon production, the method includes:

[0041] Using the accumulated data, determine the ideal power curve and the ideal hydrogen flow curve within the operation cycle of the reduction furnace;

[0042] Measure the actual power P of the silicon rod at time T i V i and compare it with the ideal power S corresponding to the ideal power curve at this time T V V V and adjust the hydrogen intake M output through PID regulation V ;

[0043] Adjust the current frequency value to make the temperature of the silicon rod within the required control range;

[0044] The trichlorosilane feed rate is automatically adjusted according to the running time.

[0045] The specific method of adjusting the output M through PID regulation V is as follows: According to the formula ΔV = P V - S V calculate at time T iThe ideal power value S corresponding to the ideal power curve V and the difference ΔV from the actual power P V ; adjust the hydrogen intake so that -20KW ≤ ΔV ≤ 20KW. If ΔV < -20KW, increase the hydrogen intake by 2 - 3 Kg / h. If ΔV > 20KW, decrease the hydrogen intake by 2 - 3 Kg / h.

[0046] The method for adjusting the current frequency is as follows: The reduction furnace is divided into several stages during the operation cycle. When the actual temperature deviates from the required ideal temperature at a certain stage of the reduction furnace operation, adjust the current frequency to keep the temperature of the silicon rod within the required control range. The method for adjusting the trichlorosilane feed rate is as follows: Increase the trichlorosilane intake by 2.5 - 3.75 Kg / min until the maximum amount is reached.

[0047] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various transformations can be made to the technical solutions of the present invention, and these simple variants all fall within the protection scope of the present invention.

[0048] In addition, it should be noted that, in the above specific embodiments, the various specific technical features and steps described can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0049] Furthermore, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A control method for the ratio of hydrogen to trichlorosilane in polysilicon production, characterized in that, The described method includes: Using the accumulated data, determine the ideal power curve and the ideal hydrogen flow rate curve within the operation cycle of the reduction furnace; Measure the actual power P of the silicon rod at time T i and compare it with the ideal power S corresponding to this time T V on the ideal power curve, and adjust the hydrogen intake M output through PID i ; V V ;​ Adjust the current frequency value to keep the temperature of the silicon rod within the required control range; The feed rate of trichlorosilane is automatically adjusted according to the operation time.

2. The control method for the ratio of hydrogen and trichlorosilane in polysilicon production according to claim 1, characterized in that, The output M adjusted by PID V The specific method is as follows: Calculate the difference ΔV between the ideal power value S corresponding to the ideal power curve at time T V and the actual power P V according to the formula ΔV = P i - S V ; V ​ Adjust the hydrogen intake to make -20KW ≤ ΔV ≤ 20KW.

3. A control method for the ratio of hydrogen to trichlorosilane in polysilicon production according to claim 2, characterized in that: If ΔV < -20KW, the hydrogen intake is increased by 2 - 3 Kg / h.

4. A control method for the ratio of hydrogen to trichlorosilane in polysilicon production according to claim 2, characterized in that: If ΔV > 20KW, the hydrogen intake is decreased by 2 - 3 Kg / h.

5. A control method for the ratio of hydrogen to trichlorosilane in polysilicon production according to claim 1, characterized in that, The adjustment method of the current frequency is as follows: The operation cycle of the reduction furnace is divided into several stages. When the actual temperature deviates from the required ideal temperature at a certain stage during the operation of the reduction furnace, adjust the current frequency to keep the temperature of the silicon rod within the required control range.

6. The control method for the ratio of hydrogen to trichlorosilane in polysilicon production according to claim 1, characterized in that, The adjustment method of the feed rate of trichlorosilane is as follows: The intake of trichlorosilane is increased by 2.5 - 3.75 Kg / min per hour until the maximum amount is reached.

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