阅读说明：本技术 单晶炉停炉预防热场损坏方法 (Method for preventing thermal field damage during shutdown of single crystal furnace ) 是由 赵贝 李增卫 赵群 于 2020-07-27 设计创作，主要内容包括：本发明提供一种单晶炉停炉预防热场损坏方法,方法包括步骤1,石英坩埚内有剩料熔融硅液时,拉制晶体,晶体的第一长度进入水冷热屏；步骤2,晶体拉制到第二长度后,停止拉制晶体,且晶体的一端与熔融硅液液面接触；步骤3,在晶体静止后,单晶炉底部的副加热器加热功率下降为零；步骤4,单晶炉四周的主加热器分三个阶段降低功率,直至主加热器加热功率下降为零；步骤5,冷却一定时间后拆单晶炉。根据本发明实施例的方法,能够拉制一定长度单晶增大迁热体积,加快石英坩埚中部熔融硅液凝结速度,降低了应力集中度,单晶炉上加热器阶梯式停止加热,减缓石英坩埚四周硅凝结速度,让出应力释放区,从而最大限度的保证热场的完整性。(The invention provides a method for preventing a thermal field from being damaged when a single crystal furnace is stopped, which comprises the following steps of 1, when molten silicon liquid with residual materials exists in a quartz crucible, drawing crystals, wherein a first length of the crystals enters a water-cooling heat shield; step 2, stopping crystal drawing after the crystal is drawn to a second length, wherein one end of the crystal is in contact with the liquid level of the molten silicon liquid; step 3, after the crystal is static, the heating power of the auxiliary heater at the bottom of the single crystal furnace is reduced to zero; step 4, reducing the power of the main heater around the single crystal furnace in three stages until the heating power of the main heater is reduced to zero; and 5, cooling for a certain time, and then disassembling the single crystal furnace. According to the method provided by the embodiment of the invention, a single crystal with a certain length can be pulled to increase the heat transfer volume, the condensation speed of molten silicon in the middle of the quartz crucible is increased, the stress concentration ratio is reduced, the heating of the heater on the single crystal furnace is stopped in a stepped manner, the condensation speed of silicon around the quartz crucible is reduced, and a stress release area is made out, so that the integrity of a thermal field is ensured to the maximum extent.)

1. A method for preventing thermal field damage during furnace shutdown of a single crystal furnace is characterized by comprising the following steps: a quartz crucible for containing molten silicon, a water-cooling heat shield arranged above the quartz crucible, an auxiliary heater arranged at the bottom of the single crystal furnace, and a main heater arranged around the quartz crucible and positioned below the water-cooling heat shield,

the method comprises the following steps:

step 1, when molten silicon liquid with residual materials exists in the quartz crucible, crystals are drawn, and a first length of the crystals enters the water-cooling heat shield;

step 2, after the crystal is drawn to a second length, stopping drawing the crystal, so that the crystal is static, one end of the crystal is in contact with the liquid level of the molten silicon liquid, and the first length is smaller than the second length;

step 3, after the crystal is static, the heating power of an auxiliary heater at the bottom of the single crystal furnace is reduced to zero;

step 4, reducing the power of the main heater around the single crystal furnace in three stages until the heating power of the main heater is reduced to zero;

and 5, cooling for a certain time, and then disassembling the single crystal furnace.

2. The method of claim 1, wherein the secondary heater heats the crystal at a power of 15kw during the drawing of the crystal.

3. The method of claim 1, wherein the main heater heats the crystal at a power of 45-60kw during the drawing.

4. The method as claimed in claim 1, wherein the second length of the crystal is between 300-500mm when the remaining molten silicon in the quartz crucible is 250-450 kg.

5. The method as recited in claim 4, wherein the first length is between 200 and 400 mm.

6. The method of claim 1, wherein the three stages in step 4 are stepped down power, wherein in the first stage, the main heater power is decreased by 10kw at 30 min.

7. The method of claim 6, wherein in step 4, the main heater power continues to drop by 15kw at 60min during a second phase following the first phase.

8. The method of claim 7, wherein in the step 4, in a third stage after the second stage, when the main heater power is 90min, the power is reduced to zero to stop heating.

9. The method as claimed in claim 7, wherein the water-cooling heat shield is provided with circulating cooling water therein to rapidly cool the crystal.

10. The method of claim 1, wherein the crystal is pulled as a dislocation mono-or poly-crystal.

Technical Field

The invention mainly relates to the technical field of crystal material processing equipment, in particular to a method for preventing thermal field damage by blowing out a single crystal furnace.

Background

During the unconventional furnace shutdown, the liquid silicon can generate a volume expansion phenomenon in the solidification and cooling processes, the crystallization sequence of the liquid silicon is that a crystallization surface is formed at the liquid level first, the crystallization surface can extend downwards along with the temperature reduction, but the liquid silicon near the middle bottom forms a heat insulation layer due to the upper crystallization, so that the middle bottom liquid silicon and the upper crystallization surface form a large temperature gradient, and the change can form stress which is difficult to release from the upper part under the inverse ratio curve of the temperature and the time.

The volume change of the liquid silicon can search weak points around the quartz crucible, but the volume change is often restricted by the quartz crucible and a crucible cover for supporting the quartz crucible and can not be carried out freely, so that internal stress is generated, the stress is highest along with slow contact with the external normal temperature, and the container and the supporting container can not bear damage.

Disclosure of Invention

In view of the above, the present invention provides a method for preventing thermal field damage during furnace shutdown of a single crystal furnace, which is used to guide out the heat source stress in the thermal field of the single crystal furnace, so as to prevent the crystal surface of the liquid silicon at the bottom of the quartz crucible and the upper part of the quartz crucible from forming a large temperature to generate stress and damage the integrity of the thermal field when the molten silicon is condensed.

In order to solve the technical problems, the invention adopts the following technical scheme:

according to the method for preventing the thermal field damage of the single crystal furnace in the shutdown process, the single crystal furnace comprises the following steps: a quartz crucible for containing molten silicon, a water-cooling heat shield arranged above the quartz crucible, an auxiliary heater arranged at the bottom of the single crystal furnace, and a main heater arranged around the quartz crucible and positioned below the water-cooling heat shield,

the method comprises the following steps:

step 1, when molten silicon liquid with residual materials exists in a quartz crucible in a thermal field, crystals are drawn, and a first length of the crystals enters a water-cooling heat shield;

step 2, after the crystal is drawn to a second length, stopping drawing the crystal, so that the crystal is static, one end of the crystal is in contact with the liquid level of the molten silicon liquid, and the first length is smaller than the second length;

step 3, after the crystal is static, the heating power of an auxiliary heater at the bottom of the single crystal furnace is reduced to zero;

step 4, reducing the power of the main heater around the single crystal furnace in three stages until the heating power of the main heater is reduced to zero;

and 5, cooling for a certain time, and then disassembling the single crystal furnace.

Preferably, the sub-heater heats the crystal with a power of 15 kw.

Preferably, the main heater has a heating power of 45-60kw when the crystal is drawn.

Preferably, the second length of the crystal is between 300-500mm when the residual molten silicon liquid in the quartz crucible is 250-450 kg.

Preferably, the first length is between 200 and 400 mm.

Preferably, the three stages in step 4 are stepwise power reduction, wherein, in the first stage, the power of the main heater is reduced by 10kw at 30 min.

Preferably, in step 4, in a second phase after the first phase, the main heater power continues to decrease by 15kw at 60 min.

Preferably, in the step 4, in a third stage after the second stage, when the main heater power is 90min, the power is reduced to zero to stop heating.

Preferably, the water-cooling heat shield is internally provided with circulating cooling water to rapidly cool the crystal.

Preferably, the crystal is pulled as a dislocation single crystal or polycrystal.

The technical scheme of the invention at least has one of the following beneficial effects:

according to the method for preventing the thermal field damage caused by the shutdown of the single crystal furnace, a single crystal with a certain length can be pulled, the heat transfer volume is increased, the condensation speed of molten silicon in the middle of the quartz crucible is increased, the single crystal enters the water-cooling heat shield, the heat transfer source is increased, the auxiliary heating at the bottom of the single crystal furnace is stopped, the lower crystallization speed is increased, the stress concentration is reduced, the heating of the upper heater of the single crystal furnace is stopped in a stepped mode, the silicon condensation speed on the periphery of the quartz crucible is reduced, and the stress release area is made out, so that the integrity of the thermal field.

Drawings

FIG. 1 is a schematic view of a method for preventing thermal field damage by blowing out a single crystal furnace according to an embodiment of the invention;

FIG. 2 is a cross-sectional view of a thermal field and a relationship between a single crystal and a water-cooled heat shield and a molten silicon bath according to an embodiment of the present invention.

Reference numerals:

a quartz crucible 10;

molten silicon 20;

a main heater 30;

a sub-heater 40;

a crystal 50;

the heat shield 60 is water-cooled.

Detailed Description

The method for preventing thermal field damage of the furnace blowing out of the single crystal furnace according to the first aspect of the invention is described in detail below with reference to the attached drawings.

In order to facilitate understanding of the method for preventing thermal field damage by stopping a single crystal furnace according to the present application, a description will be given first of all of a structure of a single crystal furnace, as shown in fig. 2, which includes: the single crystal furnace comprises a quartz crucible 10 for containing molten silicon liquid 20, a water-cooling heat shield 60 arranged above the quartz crucible 10, a secondary heater 40 arranged at the bottom of the single crystal furnace, and a main heater 30 arranged at the periphery of the quartz crucible 10 and positioned below the water-cooling heat shield 60.

The method for preventing thermal field damage in the furnace shutdown of the single crystal furnace according to the embodiment of the invention is described in detail below with reference to fig. 1 and 2, and as shown in fig. 1, the method comprises the following steps:

step S100, when the residual molten silicon liquid exists in the thermal field quartz crucible 10, the crystal 50 is drawn, and the first length of the crystal 50 enters the water-cooling heat shield 60.

Step S200, after the crystal 50 is pulled to the second length, stopping pulling the crystal 50, so that the crystal 50 is stationary and one end of the crystal 50 contacts with the liquid level of the molten silicon liquid, and the first length is smaller than the second length.

In step S300, after the crystal 50 is stationary, the heating power of the sub-heater 40 at the bottom of the single crystal furnace is reduced to zero.

Step S400, the power of the main heater 30 around the single crystal furnace is reduced in three stages until the heating power of the main heater 30 is reduced to zero.

And step S500, cooling for a certain time and then disassembling the single crystal furnace.

It should be noted that the more applicable conditions of the method for preventing thermal field damage by stopping the furnace of the single crystal furnace of the present invention require that the quartz crucible 10 is intact without leakage or slightly siliconized, a single crystal with a normal regular crystal 50 arrangement cannot be pulled due to mechanical or software reasons of the single crystal furnace, or the crucible wall of the quartz crucible 10 deforms or forms bubbles to affect the single crystal pulling, at this time, an unconventional furnace stopping is required, and since the furnace stopping is required, the temperature in the furnace is still high, and in order to avoid the thermal field damage, the method for preventing thermal field damage by stopping the furnace of the single crystal furnace of the embodiment of the present invention needs to be adopted to perform the unconventional furnace stopping.

For example, when 450kg of the molten silicon solution 20 remains in the quartz crucible 10, a section of the crystal 50 is first pulled from the position of the liquid level of the molten silicon solution 20 by the steps of seeding, shouldering, shoulder rotating and constant diameter, wherein the crystal 50 may be a single crystal or a polycrystalline material, and the single crystal or the polycrystalline material is a single crystal or a polycrystalline material with the same volume which does not form a regular crystal arrangement and does not belong to a normally produced single crystal product.

In step S100, the first length of the drawn crystal 50 enters the water-cooling heat shield 60, wherein the water-cooling heat shield 60 can rapidly cool the crystal 50, and the heat in the quartz crucible 10 is guided from the high-temperature molten silicon 20 to the low-temperature crystal 50 of the water-cooling heat shield 60, so that a heat transfer source is added, and therefore, the heat source stress in the quartz crucible 10 can be guided out, and the thermal field can be prevented from being damaged.

In step S200, a second length of the single crystal or the polycrystalline material, i.e. the total length of the pulled crystal 50, is determined according to the amount of the remaining molten silicon, wherein the second length is determined according to the amount of the remaining molten silicon, when the amount of the remaining molten silicon is larger, the total length of the pulled crystal or the polycrystalline material is longer, for example, when the molten silicon 20 in the quartz crucible 10 is left at 250-. When the pulling crystal 50 reaches the second length, the pulling of the crystal 50 is finished, the crystal 50 with the second length is kept static, one end of the crystal is in contact with the liquid level of the molten silicon liquid, and the other end of the crystal enters the water-cooling heat shield 60, so that a single crystal or polycrystal material with a certain length is pulled, the heat transfer volume of the molten silicon liquid 20 can be effectively increased, the condensation speed of the molten silicon liquid 20 in the middle is increased, meanwhile, the crystal 50 enters the water-cooling heat shield 60, the heat transfer source is increased, and the integrity of the heat field is guaranteed to the maximum extent.

In step S300, when the pulling of the crystal 50 is finished, the power of the sub-heater 40 at the bottom of the single crystal furnace is reduced to zero. According to an embodiment of the present application, the heating power of the sub-heater 40 at the bottom of the single crystal furnace is 15kw when the crystal 50 is pulled, that is, the heating power of the sub-heater 40 at the bottom of the single crystal furnace is reduced from 15kw to zero when the crystal 50 is pulled to the second length, whereby the heating of the bottom of the single crystal furnace is stopped first, the crystallization speed at the lower portion of the quartz crucible 10 can be increased, and the concentration of stress in the quartz crucible 10 can be reduced.

According to an embodiment of the present application, in step S400, the main heater 30 may be heated at 45-60kw during the drawing of the crystal 50 and the power may be reduced stepwise in three stages, the three stages being the first stage, the second stage and the third stage, for example, when the main heater 30 is heated at 45kw during the drawing of the crystal 50, the power of the main heater 30 is reduced by 10kw during 30min during the first stage when the heating power is 35kw, the power of the main heater 30 is further reduced by 15kw during the second stage when the heating power is 60min, the power is 20kw during the third stage when the power of the main heater 30 is 90min, and the power is further reduced by 20kw, i.e., reduced to zero, and the heating is stopped. The heating is stopped in a step mode through the main heater 30, the silicon condensation speed around the quartz crucible 10 is slowed down, a release area is given to stress, the release of the stress to the periphery is weakened, and the zero loss of unconventional furnace shutdown in a thermal field is reduced or achieved.

The power matching between the main heater 30 and the sub-heater 40 is to reduce the temperature gradient of the quartz crucible 10, slow down the heat release rate of the molten silicon 20 crystallization, reduce the short-time stress concentration, and promote the gradual release of the stress from the upper portion of the quartz crucible 10.

In step S500, after cooling for a certain time, according to an embodiment of the present application, the cooling time is about 7 to 8 hours, when the temperature in the single crystal furnace drops below 300 ℃, the single crystal furnace can be disassembled, the thermal field component that is not damaged by stress in the furnace can be obtained and cleaned, and the cleaned thermal field component can enter the next furnace for crystal processing.

According to an embodiment of the application, be equipped with recirculated cooling water in the water cooling heat shield 60 to crystal 50 rapid cooling, from this, crystal 50 of first length gets into the hydrothermal cold shield, can be at the at utmost in the circulation process take away crystal 50's heat, is a heat migration body that the radiating effect is fine, lets the migration ability multiplication, thereby makes the internal stress obtain fully releasing.

According to one embodiment of the present application, crystal 50 is pulled as dislocation single crystal 40 or polycrystal, the reason for the unconventional furnace shutdown is that crystal 50 cannot be pulled normally, quartz crucible 10 is generally not broken, single crystal cannot be pulled due to mechanical or software reasons of the single crystal furnace, or wall deformation or bubble formation of quartz crucible 10 affects the pulling of the single crystal, and pulled crystal 50 does not form a single crystal of the same volume with regular crystal 50 arrangement, and belongs to dislocation single crystal 40 or polycrystal.

According to the method for preventing the thermal field damage caused by the shutdown of the single crystal furnace, a single crystal with a certain length can be pulled, the heat transfer volume is increased, the condensation speed of molten silicon in the middle of the quartz crucible is increased, the single crystal enters the water-cooling heat shield, the heat transfer source is increased, the auxiliary heating at the bottom of the single crystal furnace is stopped, the lower crystallization speed is increased, the stress concentration is reduced, the main heater on the single crystal furnace stops heating in a stepped mode, the silicon condensation speed on the periphery of the quartz crucible is reduced, and the stress release area is made away, so that the integrity of the thermal field is ensured to the.

Other configurations and operations of the novel seed crystal processing apparatus according to embodiments of the present invention are understood and readily implemented by those skilled in the art and will not be described in detail.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.