Single crystal furnace heating system and regulation and control method

Abstract

The invention relates to the technical field of single crystal furnace heating, in particular to a single crystal furnace heating system and a regulation and control method.The single crystal furnace heating system comprises a main heater, an auxiliary heater and a sub-control model, the main heater is arranged on the periphery of a crucible in a sleeving mode and fixedly connected with the bottom wall of a furnace body, and the auxiliary heater is fixedly connected with the bottom wall of the furnace body and located at the bottom of the main heater; in order to finely control the temperature gradient of a solution, reduce the oxygen content of a crystal bar and stabilize a thermal field, the structure of the heater is designed, a radiation area comprises the side wall of the crucible, the heating efficiency is improved, and the energy consumption is reduced; the main heater and the auxiliary heater are separately controlled, the temperature gradient of the solution is controlled more finely, crystallization is facilitated, power distribution of the main heater and the auxiliary heater is calculated and regulated through the sub-control model, and under the condition of stabilizing the per unit yield, the oxygen content of the crystal bar is further reduced, and the quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single crystal furnace heating, in particular to a single crystal furnace heating system and a control method. BACKGROUND

[0002] The single crystal furnace heating system is generally a combination of a main heater and a bottom heater. The heating area of the main heater is located on the side wall of the furnace, which mainly provides heat to the straight wall area of the crucible side through heat radiation, and then conducts the heat to the straight wall area of the crucible side through heat transfer. The bottom heater is located on the bottom of the furnace, which mainly provides heat to the crucible support area through heat radiation, and then conducts the heat to the bottom area of the crucible through heat transfer through the bottom of the crucible. The final effect is to melt the silicon material in the melting process and dynamically stabilize the temperature gradient in the growth stage.

[0003] For example, a single crystal furnace auxiliary heater, heating system and single crystal furnace are disclosed in Chinese Patent No. CN221398160U. The single crystal furnace auxiliary heater includes a heating body and at least two auxiliary heater foot plates. The heating body and the at least two auxiliary heater foot plates are connected in a detachable manner. The heating body is provided as a closed loop structure with a circular projection on a horizontal plane, and at least two recessed space accommodating spaces are formed on the heating body. One end of each auxiliary heater foot plate is connected to the heating body, and the other end is connected to the auxiliary heater electrode. The single crystal furnace auxiliary heater of this scheme can shorten the melting time and reduce the oxygen content in the single crystal silicon rod when combined with the existing heating system.

[0004] With the changes in product market demand and the upgrading and iteration of the heat field technology, in order to reduce the oxygen content of the single crystal rod, the heating area of the main heater has a tendency to become shorter. However, controlling the heat field by simply shortening the heating area of the main heater has the following negative effects: 1. The longitudinal temperature gradient of the heat field is too large, increasing the difficulty of crystal growth; 2. The heat loss of the main heater and the bottom heater to the lower part of the straight wall of the crucible is large, and the energy consumption of the melting time is increased; 3. At the same time, long-term high temperature will increase the silicon monoxide generated by the reaction of the crucible and the silicon liquid, ultimately affecting the oxygen content of the crystal rod. Therefore, a single crystal furnace heating system and a control method are needed to solve the above problems. SUMMARY

[0005] The purpose of the present application is to provide a single crystal furnace heating system and a control method, which can adjust the power of the main heater and the auxiliary heater according to the crystal pulling power, achieve fine control of the temperature gradient of the melt, reduce the oxygen content of the crystal rod, and stabilize the heat field, thereby improving the quality of crystal pulling and reducing energy consumption.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] The application provides a single crystal furnace heating system and a control method.

[0008] Preferably, the main heater and the auxiliary heater each comprise a heating area and a plurality of supports, the heating area is in a ring structure, the bottom of the heating area is fixedly connected with the support, and the bottom of the support is fixedly connected with the bottom wall of the furnace body.

[0009] Preferably, the height of the heating area of the main heater is 150-300 mm, and the height of the heating area of the auxiliary heater is 150-300 mm.

[0010] Preferably, the distance between the lower edge of the heating area of the main heater and the upper edge of the heating area of the auxiliary heater is 25-250 mm.

[0011] The application further provides a single crystal furnace heating control method, and the single crystal furnace heating system according to claims 1-7 comprises the following steps: step one, in the material melting stage, the height of the main heater and the auxiliary heater is adjusted to keep a safe distance, and the main heater and the auxiliary heater melt the material together; step two, when the linear size of the last bucket of un-melted silicon material is 150-200 mm, the auxiliary heater is turned off, the temperature is adjusted and stabilized, and the crystal is drawn, so that the temperature of the bottom of the crucible is reduced, and the oxygen content is reduced; and step three, in the growth stage, the main heater is turned on, the auxiliary power distribution gradually increases with the decrease of the remaining silicon melt in the crucible, the temperature gradient is controlled, and the temperature gradient of the solution is finely controlled.

[0012] Preferably, the related parameters of the control model comprise the main heater power P1, the auxiliary heater power P2, the crystal drawing power P0, the temperature reduction amount Pa, the distribution ratio A, the auxiliary increase coefficient B and the main heater compensation value C, the crystal drawing power P0 and the temperature reduction amount Pa are constants, the main heater power P1 can be calculated through the crystal drawing power P0, the temperature reduction amount Pa, the distribution ratio A and the main heater compensation value C, the calculation formula of the main heater power P1 is P1=(P0-Pa)*A+C, the main heater power P1 is 70-130 KW, the auxiliary heater power P2 can be calculated through the crystal drawing power P0, the temperature reduction amount Pa, the distribution ratio A and the auxiliary increase coefficient B, the calculation formula of the auxiliary heater power P2 is P2=(P0-Pa)*(1-A)*B, and the auxiliary heater power P2 is 70-130 KW.

[0013] Preferably, after the crystal drawing reaches a proper length, the crystal pulling power is reduced, and the shoulder is put, which is helpful for crystal formation.

[0014] Preferably, after isometric completion, the crystal bar is taken out and data inspection is carried out after cooling, which can facilitate further optimization of temperature control.

[0015] Advantages of the present application:

[0016] 1. The present application improves the heating efficiency and reduces energy consumption by designing the heater structure, and the temperature gradient of the melt is more finely controlled by separately controlling the main heater and the auxiliary heater, which is beneficial to crystal formation.

[0017] 2. The sub-control model of the present application calculates the power distribution of the main heater and the auxiliary heater by parameters such as crucible rotation, furnace pressure and cooling amount, further reduces the oxygen content of the crystal bar and improves the quality under the condition of stable single yield. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0019] Fig. 1 is a sectional view of the furnace body structure of the present application.

[0020] Fig. 2 is a schematic diagram of the main heater structure of the present application.

[0021] Fig. 3 is a schematic diagram of the auxiliary heater structure of the present application.

[0022] In the drawings:

[0023] 1. Main heater; 2. Auxiliary heater; 20. Heating area; 21. Bracket; 3. Sub-control model; 4. Crucible; 5. Furnace body. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be further described below in combination with the drawings and through specific embodiments.

[0025] Among them, the drawings are only used for exemplary description, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present patent; in order to better illustrate the embodiments of the present application, some components of the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it can be understood that some known structures and their descriptions in the drawings can be omitted.

[0026] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that, if the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present patent, and for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0027] In the description of the present application, unless otherwise explicitly specified and limited, if the term "connection" and the like indicating the connection relationship between components appears, the term should be understood in a broad sense, for example, it can be fixedly connected, or can be detachably connected, or can be integrated; it can be mechanically connected, or can be electrically connected; it can be directly connected, or can be indirectly connected through an intermediate medium; it can be the communication inside two components or the interaction relationship between two components. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0028] As shown in Figs. 1 to 3

[0029] A single crystal furnace heating system and a control method, comprising a main heater 1, an auxiliary heater 2 and a sub-control model 3, the main heater 1 is sleeved outside the crucible 4 and fixedly connected with the bottom wall of the furnace body 5, the auxiliary heater 2 is fixedly connected with the bottom wall of the furnace body 5 and located at the bottom of the main heater 1, the auxiliary heater 2 is coaxially arranged with the main heater 1, and the main heater 1 and the auxiliary heater 2 are calculated and controlled in power through the sub-control model 3.

[0030] The present application changes the structure of the traditional main heater 1 and the bottom heater, and uses the auxiliary heater 2 to replace the bottom heater. The main heater 1 is located on the side wall of the furnace, and the auxiliary heater 2 is below the main heater 1. Through the design of the heater structure, the heat radiation area contains the upper and lower parts of the side wall of the crucible 4, the heating efficiency is improved, and the energy consumption is reduced. And through the separate control of the main heater 1 and the auxiliary heater 2, the temperature gradient of the melt is more finely controlled, which is beneficial to crystal growth.

[0031] As shown in Figs. 1 to 3

[0032] ​​The related parameters of the sub-control model 3 include the main heater power P1, the auxiliary heater power P2, the seed power P0, the temperature drop Pa, the distribution ratio A, the auxiliary heater value coefficient B, and the main heater compensation value C. The seed power P0 and the temperature drop Pa are constants. The main heater power P1 can be calculated by the seed power P0, the temperature drop Pa, the distribution ratio A, and the main heater compensation value C. The calculation formula of the main heater power P1 is P1=(P0-Pa)*A+C. The main heater power P1 is 70KW-130KW. The auxiliary heater power P2 can be calculated by the seed power P0, the temperature drop Pa, the distribution ratio A, and the auxiliary heater value coefficient B. The calculation formula of the auxiliary heater power P2 is P2=(P0-Pa)*(1-A)*B. The auxiliary heater power P2 is 70KW-130KW.

[0033] The main heater power P1 and the auxiliary heater power P2 are independently controlled by the sub-control model 3. In the melting process, the main heater 1 and the auxiliary heater power are high. The main heater 1 and the auxiliary heater 2 jointly provide heat for the silicon material, so that the crucible and the side of the crucible 4 are uniformly heated, which can reduce heat loss and efficiently melt the silicon material in the crucible 4. In the growth stage, the main heater 1 is turned on, the auxiliary heater power is gradually increased as the remaining silicon melt in the crucible 4 decreases, and the auxiliary heater 2 is operated at a low power or turned off to meet the appropriate temperature gradient, so that the reaction between the silicon liquid and the crucible 4 is slowed down as the temperature of the bottom of the crucible 4 decreases, and the generation of oxygen is reduced.

[0034] As shown in Figs. 1 to 3 ,

[0035] The main heater 1 and the auxiliary heater 2 each include a heating area 20 and a plurality of supports 21. The heating area 20 is in a ring structure. The bottom of the heating area 20 is fixedly connected with the support 21. The bottom of the support 21 is fixedly connected with the bottom wall of the furnace body 5.

[0036] The height of the heating area 20 of the main heater 1 is 150-300mm. The height of the heating area 20 of the auxiliary heater 2 is 150-300mm.

[0037] The distance between the lower edge of the heating area 20 of the main heater 1 and the upper edge of the heating area 20 of the auxiliary heater 2 is 25mm-250mm.

[0038] The height of the heating area 20 is reduced. On the one hand, the safety distance between the main heater 1 and the auxiliary heater 2 is ensured. On the other hand, the auxiliary heater 2 also plays a large role in the material melting stage. In order to balance the material melting efficiency of the auxiliary heater 2 and the temperature gradient in the production process, the distance between the auxiliary heater 2 and the main heater 1 is kept enough, which can ensure that the middle part of the crucible 4 also gets enough heat in the material melting process.

[0039] As shown in Fig. 1 ,

[0040] The application also provides a method for regulating the heating of a single crystal furnace, the single crystal furnace heating system according to claims 1-7, comprising the following steps: step one: in the material melting stage, the height of the main heater 1 and the auxiliary heater 2 is adjusted to keep a safe distance, and the main heater 1 and the auxiliary heater 2 melt the material together, step two: when the linear size of the last bucket of un-melted silicon material is 150-200 mm, the auxiliary heater 2 is turned off, the temperature is adjusted and stabilized, and the crystal pulling is performed, which can reduce the temperature at the bottom of the crucible 4 and thus reduce the oxygen content, step three: in the growth stage, the main heater 1 is turned on, and the auxiliary power distribution gradually increases with the decrease of the remaining silicon melt in the crucible 4, so as to control the temperature gradient and finely control the temperature gradient of the solution.

[0041] After the crystal pulling reaches a suitable length, the power is reduced and the shoulder is entered, which can help the crystal growth.

[0042] After the equal diameter is completed, the crystal rod is taken out and cooled for data inspection, which can facilitate further optimization of temperature regulation.

[0043] I. Preferred embodiment

[0044] 1. The main heater 1 is located on the side wall of the furnace, and the height of the heating area 20 is 180-200 mm.

[0045] 2. The auxiliary heater 2 is below the main heater 1, and the two are coaxial, and the distance between the main heater 1 and the auxiliary heater 2 is 150-200 mm.

[0046] 3. The height of the heating area 20 of the auxiliary heater 2 is 220-260 mm.

[0047] 4. The distance between the auxiliary heater 2 and the furnace bottom is 20-50 mm.

[0048] 5. The crucible 4 is wrapped inside the main heater 1 and the auxiliary heater 2.

[0049] 6. In the material melting stage, the main heater 1 and the auxiliary heater 2 melt the material together, the main heater power is 100-110 KW, and the auxiliary heater power is 90-100 KW.

[0050] 7. When the linear size of the last bucket of un-melted silicon material is 150-200 mm, the auxiliary heater 2 is turned off.

[0051] 8. The temperature is adjusted and stabilized, the main heater power is set to 63 KW for crystal pulling, the average pulling speed is 280 mm / hr, and the.

[0052] 9. After the crystal pulling reaches a suitable length, the power and the pulling speed are reduced, and the shoulder is entered.

[0053] 10. At the equal diameter 1-80mm, the cooling amount is 12KW, the distribution ratio is 0.85, the auxiliary added value coefficient is 1.2, the main added compensation value is 0KW, and according to the formula

[0054] P1 = (P0 - Pa) * A + C

[0055] P2 = (P0 - Pa) * (1 - A) * B

[0056] The system calculates the main heater power to be 43.4KW and the auxiliary heater power to be 9.2KW through the formula.

[0057] At the equal diameter 81-200mm, the main heater power is distributed to be 44.9KW and the auxiliary heater power is distributed to be 7.3KW.

[0058] 11. Due to the expansion of the process window, the crucible rotation and the furnace pressure can be further reduced, and the parameters at the equal diameter stage are referred to the following table:

[0059]

[0060]

[0061] 12. After the equal diameter is completed, the end program is started.

[0062] 13. The crystal bar is taken out, and after cooling, data inspection is performed.

[0063] Through experiments, the oxygen content of the head of the crystal bar is reduced by 2ppm.

[0064] II. First Comparative Example

[0065] 1. The main heater 1 is located on the side wall of the furnace, and the heating area 20 has a height of 180-200mm.

[0066] 2. The auxiliary heater 2 is below the main heater 1, and the two are coaxial, with a distance of 40-60mm between the main heater and the auxiliary heater.

[0067] 3. The heating area 20 of the auxiliary heater 2 has a height of 250mm-280mm.

[0068] 4. The distance between the auxiliary heater 2 and the furnace bottom 3 is 20-50mm.

[0069] 5. The crucible 4 is wrapped inside the main heater 1 and the auxiliary heater 2.

[0070] 6. During the material melting stage, the main heater 1 and the auxiliary heater 2 jointly melt the material, with the main heater power being 90-100KW and the auxiliary heater power being 100-110KW.

[0071] 7. When the last bucket of un-melted silicon material has a linear dimension of 150mm-200mm, turn off the 2 auxiliary heaters 2.

[0072] 8. Temperature adjustment and stabilization, the 1 main heater power is set to 64KW for seed crystal pulling, the average pulling speed is 280mm / hr, and the temperature is entered.

[0073] 9. After the seed crystal reaches the appropriate length, reduce the power and the pulling speed, and enter the shoulder.

[0074] 10. At the constant diameter 1-80mm, the temperature reduction is 14KW, the distribution ratio is 0.85, the auxiliary heating value coefficient is 1.1, the main heating compensation value is 0KW, and the formula is

[0075] P1=(P0-Pa)*A+C

[0076] P2=(P0-Pa)*(1-A)*B

[0077] The system calculates the distribution of the main heater power as 42.5KW and the auxiliary heater power as 8.3KW through the formula.

[0078] At the constant diameter 81-200mm, the distribution of the main heater power is 44KW and the auxiliary heater power is 6.6KW.

[0079] 11. The constant diameter stage parameters are operated according to the following table:

[0080]

[0081] 12. After the constant diameter is completed, the finishing program is started.

[0082] 13. The crystal bar is taken out, cooled, and then data inspection is performed.

[0083] Through experiments, the crystal pulling breakage rate is reduced by 4-8%, and the crystal bar yield is increased by 5kg.

[0084] It should be noted that the above specific embodiments are only the preferred embodiments of the present application and the technical principles applied. Those skilled in the art should understand that various modifications, equivalent replacements, changes, etc. can be made to the present application. However, as long as these changes do not deviate from the spirit of the present application, they should be within the protection scope of the present application. In addition, some terms used in the present application specification and claims are not limited, but only for the convenience of clearly describing the positional relationship and function between the components.

Claims

1. A single crystal furnace heating system, comprising a main heater (1), an auxiliary heater (2) and a sub-control model (3), wherein the main heater (1) is fitted around the crucible (4) and fixedly connected to the bottom wall of the furnace body (5), the auxiliary heater (2) is fixedly connected to the bottom wall of the furnace body (5) and located at the bottom of the main heater (1), the auxiliary heater (2) is coaxially arranged with the main heater (1), and the main heater (1) and the auxiliary heater (2) calculate the power through the sub-control model (3).

2. The single crystal furnace heating system of claim 1, wherein, Both the main heater (1) and the auxiliary heater (2) include a heating zone (20) and multiple supports (21). The heating zone (20) is a ring structure. The bottom of the heating zone (20) is fixedly connected to the support (21), and the bottom of the support (21) is fixedly connected to the bottom wall of the furnace body 5.

3. The single crystal furnace heating system and regulation method of claim 2, wherein, The height of the heating zone (20) of the main heater (1) is 150-300mm, and the height of the heating zone (20) of the auxiliary heater (2) is 150-300mm.

4. The single crystal furnace heating system and control method according to claim 2, characterized in that, The distance between the lower edge of the heating zone (20) of the main heater (1) and the upper edge of the heating zone (20) of the auxiliary heater (2) is 25mm-250mm.

5. A single crystal furnace heating system and control method, characterized in that, A single crystal furnace heating system according to claims 1-7 includes the following steps; Step 1: During the material preparation stage, adjust the height of the main heater (1) and the auxiliary heater (2) to maintain a safe distance between them, and have the main heater (1) and the auxiliary heater (2) work together to prepare the material; Step 2: When the linear size of the last unmelted silicon material is 150mm~200mm, turn off the auxiliary heater (2) and adjust and stabilize the temperature. At the same time, crystal pulling is carried out, which can reduce the temperature at the bottom of crucible 4 and thus reduce the oxygen content. Step 3: During the growth stage, the main heater (1) is turned on, and the auxiliary power distribution gradually increases as the remaining silicon melt in the crucible 4 decreases, controlling the temperature gradient and enabling precise control of the temperature gradient of the melt.

6. The single crystal furnace heating system and control method according to claim 5, characterized in that, The relevant parameters of the sub-control model (3) include the main heater power P1, the auxiliary heater power P2, the crystal pulling power P0, the cooling amount Pa, the distribution ratio A, the auxiliary heater value-added coefficient B, and the main heater compensation value C. The crystal pulling power P0 and the cooling amount Pa are both constants. The main heater power P1 can be calculated using the crystal power P0, cooling amount Pa, distribution ratio A, and main heater compensation value C. The formula for calculating the main heater power P1 is P1 = (P0 - Pa) * A + C, and the main heater power P1 is 70KW~130KW. The auxiliary heater power P2 can be calculated using the crystal power P0, cooling amount Pa, distribution ratio A, and auxiliary addition coefficient B. The formula for calculating the auxiliary heater power P2 is P2=(P0-Pa)*(1-A)*B, and the auxiliary heater power P2 is 70KW~130KW.

7. The single crystal furnace heating system and control method according to claim 5, characterized in that, Once the crystal reaches the appropriate length, reducing the crystal pulling power and entering the shoulder formation stage can help with crystal formation.

8. The single crystal furnace heating system and control method according to claim 5, characterized in that, After the crystal rod is made of constant diameter, it is removed, cooled, and the data is checked, which facilitates further optimization of temperature control.

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