阅读说明：本技术 一种单晶炉及用该单晶炉进行直拉单晶稳温工艺 (Single crystal furnace and temperature stabilizing process for pulling single crystal by using single crystal furnace ) 是由 吴树飞 王林 高润飞 谷守伟 王建平 周泽 杨志 赵国伟 刘振宇 郝瑞军 刘学 于 2020-04-24 设计创作，主要内容包括：本发明提供一种单晶炉,包括炉盖和主炉室,还具有若干用于监测所述主炉室石英坩埚中熔硅液面上设定区域内的温度监控装置,所述监控装置置于所述炉盖内侧且被置于所述主炉室导流筒的斜上方；所述监控装置均朝所述设定区域方向倾斜设置。本发明还提出一种用该单晶炉进行直拉单晶稳温工艺。本发明通过设置用于熔硅液面尤其是靠近中心位置处的温度,实现熔硅液面温度监控自动调整,以保证稳温拉制工序中固液界面温度的横定,为后续成功引晶奠定基础,监控区域设置合理,监控温度精准且易于控制,实现熔硅液面温度的自动调节,从而保证单晶晶体生长温度梯度的一致性,提高生产效率。(The invention provides a single crystal furnace, which comprises a furnace cover, a main furnace chamber and a plurality of temperature monitoring devices for monitoring the temperature in a set area on the liquid level of molten silicon in a quartz crucible of the main furnace chamber, wherein the monitoring devices are arranged on the inner side of the furnace cover and are arranged obliquely above a guide cylinder of the main furnace chamber; the monitoring devices are all obliquely arranged towards the direction of the set area. The invention also provides a temperature stabilizing process for pulling the single crystal by using the single crystal furnace. The invention realizes the automatic regulation of the temperature monitoring of the liquid level of the molten silicon by setting the temperature for the liquid level of the molten silicon, particularly the temperature close to the central position, so as to ensure the transverse determination of the temperature of a solid-liquid interface in the stable temperature drawing process, lay the foundation for the subsequent successful crystal seeding, have reasonable setting of a monitoring area, accurate and easy control of the monitoring temperature, and realize the automatic regulation of the temperature of the liquid level of the molten silicon, thereby ensuring the consistency of the growth temperature gradient of the single crystal and improving the production efficiency.)

1. A single crystal furnace comprises a furnace cover and a main furnace chamber, and is characterized by also comprising a plurality of temperature monitoring devices for monitoring the temperature in a set area on the liquid level of molten silicon in a quartz crucible of the main furnace chamber, wherein the monitoring devices are arranged on the inner side of the furnace cover and are arranged obliquely above a guide cylinder of the main furnace chamber; the monitoring devices are all obliquely arranged towards the direction of the set area.

2. The single crystal furnace as claimed in claim 1, wherein the monitoring device is provided on a side near an upper end opening of the furnace lid; the monitoring device is at least arranged in a staggered manner with the CCD camera arranged on the furnace cover; the monitoring device and the CCD camera are positioned on the same radial circumference.

3. The single crystal furnace according to claim 1 or 2, wherein the monitoring device comprises a cover body and a temperature measuring instrument arranged on the inner side of the cover body, the cover body is a groove body with an opening at the upper end and is arranged close to one side of the furnace cover; the inclination direction of the cover body is matched with the thermometer.

4. The single crystal furnace according to claim 3, wherein the setting region is provided near a center of the surface of the molten silicon, and the setting region includes at least a solid-liquid interface; the minimum distance between the set area and the solid-liquid interface is 0-15 mm.

5. The single crystal furnace of any one of claims 1 to 2 and 4, further comprising a controller disposed outside the single crystal furnace, wherein the controller is configured to receive and process data measured by the monitoring device.

6. A temperature stabilizing process of czochralski single crystal is characterized in that the single crystal furnace according to any one of claims 1 to 5 is adopted, and the monitoring device is used for carrying out temperature monitoring on the set area in the solid-liquid interface to obtain a plurality of groups of temperature test values; taking the average value of all the test values, and comparing the average value with a standard value of the temperature-stabilizing temperature; and adjusting the heater power to make the average value within the standard value range.

7. The temperature stabilizing process according to claim 6, wherein when the average value is smaller than the standard value, the raising of the heater power and the heating of the heater power at a set temperature-raising coefficient are carried out until the average value of the obtained temperature is within the range of the standard value.

8. The temperature stabilizing process according to claim 7, wherein when the average value is larger than the standard value, the lowering of the heater power and the heating of the heater power at a set temperature lowering coefficient are performed until the average value of the obtained temperature is within the range of the standard value.

9. A Czochralski single crystal temperature stabilizing process as set forth in claim 8, wherein the temperature increase coefficient is 1.2-1.5; the temperature reduction coefficient is 0.5-0.7.

10. The temperature stabilizing process for Czochralski single crystal as claimed in any one of claims 6 to 9, wherein the standard value of the temperature stabilizing temperature is 1430-1475 ℃.

Technical Field

The invention belongs to the field of pulling of Czochralski single crystals, and particularly relates to a single crystal furnace and a temperature stabilizing process for Czochralski single crystals by using the single crystal furnace.

Background

In the Czochralski single crystal process, the temperature of a thermal field is one of key parameters for ensuring the single crystal pulling, the temperature control on the existing solid-liquid interface is to arrange an infrared inductor above a pulling head to monitor the liquid level temperature, but when the crystal pulling and diameter equalizing steps are carried out, the infrared inductor for liquid level control is arranged above the pulling head and can be shielded by crystals which are gradually lifted in the single crystal pulling process, so that the liquid level control needs to be closed, at the moment, the pulling speed can only be manually adjusted, and the temperature stabilization temperature is determined by observing the projection brightness of the solid-liquid interface from a CCD window into a furnace body, so as to ensure the temperature of the solid-liquid interface to be constant in the diameter equalizing process. However, the operation mode needs to be judged according to the experience of personnel, the requirement on the operation skill is high, but the operation mode cannot be unified and quantized, the crystal pulling failure caused by judgment errors is easy to occur, the quality difference of the pulled single crystal is large, the pulled single crystal cannot be unified, and the follow-up tracing is difficult. For the quartz crucible and the thermal field used by repeated casting and drawing, the self heat preservation function is not accurate any more, and the normal operation of single crystal drawing can be ensured only by increasing the temperature monitoring of a solid-liquid interface.

In addition, in the actual production process, one operator needs to be responsible for the drawing work of a plurality of single crystal furnaces, and in the temperature stabilizing and drawing process of each single crystal furnace, the operator needs to observe the projection brightness of the solid-liquid interface all the time to adjust, so that the operator cannot consider the operation of other furnace platforms, the probability of abnormal accidents caused by the dispersed energy of the operator can be increased, and greater economic loss is caused.

Disclosure of Invention

The invention aims to provide a single crystal furnace and a temperature stabilizing process for pulling a single crystal by using the single crystal furnace, particularly monitor the liquid level temperature in the temperature stabilizing process, have accurate monitoring temperature, can automatically adjust the temperature range to ensure the constancy of the liquid level temperature in the temperature stabilizing process, and have the advantages of simple structure, reasonable design, strong practicability, safety and controllability.

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

a single crystal furnace comprises a furnace cover, a main furnace chamber and a plurality of temperature monitoring devices for monitoring the temperature in a set area on the liquid level of molten silicon in a quartz crucible of the main furnace chamber, wherein the monitoring devices are arranged on the inner side of the furnace cover and are arranged obliquely above a guide cylinder of the main furnace chamber; the monitoring devices are all obliquely arranged towards the direction of the set area.

Further, the monitoring device is arranged on one side close to the upper end opening of the furnace cover; the monitoring device is at least arranged in a staggered manner with the CCD camera arranged on the furnace cover; the monitoring device and the CCD camera are positioned on the same radial circumference.

Further, the monitoring device comprises a cover body and a temperature measuring instrument arranged on the inner side of the cover body, wherein the cover body is a groove body with an opening at the upper end and is arranged close to one side of the furnace cover; the inclination direction of the cover body is matched with the thermometer.

Further, the setting area is arranged close to the central position of the liquid level of the molten silicon, and the setting area at least comprises a solid-liquid interface; the minimum distance between the set area and the solid-liquid interface is 0-15 mm.

Further, the single crystal furnace also comprises a controller arranged outside the single crystal furnace, and the controller is used for receiving and processing the data measured by the monitoring device.

A temperature stabilizing process for pulling a Czochralski single crystal adopts the single crystal furnace as described in any one of the above, the monitoring device is executed to carry out temperature monitoring on the set area in a solid-liquid interface, and a plurality of groups of temperature test values are obtained; taking the average value of all the test values, and comparing the average value with a standard value of the temperature-stabilizing temperature; and adjusting the heater power to make the average value within the standard value range.

Further, when the average value is smaller than the standard value, the heater power is increased and the heater power is heated by setting a temperature rise coefficient until the average value of the obtained temperature is within the range of the standard value.

Further, when the average value is larger than the standard value, reducing the heater power and heating the heater power by setting a temperature reduction coefficient until the obtained temperature is within the range of the standard value.

Further, the temperature rise coefficient is 1.2-1.5; the temperature reduction coefficient is 0.5-0.7.

Further, the standard value of the temperature stabilizing temperature is 1430-1475 ℃.

Compared with the prior art, by adopting the technical scheme, the temperature of the molten silicon liquid level is automatically monitored and adjusted by setting the temperature of the molten silicon liquid level, particularly the temperature close to the central position, so that the temperature of a solid-liquid interface in a temperature-stabilizing drawing process is ensured to be transversely fixed, a foundation is laid for subsequent successful seeding, a monitoring area is reasonably set, the monitoring temperature is accurate and easy to control, and the automatic adjustment of the temperature of the molten silicon liquid level is realized; meanwhile, the temperature around the solid-liquid interface in the subsequent crystal drawing process can be monitored, so that the consistency of the growth temperature gradient of the single crystal can be ensured, and the production efficiency is improved.

Drawings

FIG. 1 is a schematic structural view of a single crystal furnace according to a first embodiment of the present invention;

FIG. 2 is a top view of a monitoring device on a furnace lid according to a first embodiment of the present invention;

FIG. 3 is a view showing the position of a setting region in a quartz crucible according to a first embodiment of the present invention;

FIG. 4 is a view showing the position of a setting region in a quartz crucible according to a second embodiment of the present invention;

FIG. 5 is a schematic view showing the structure of a single crystal furnace according to a second embodiment of the present invention;

fig. 6 is a plan view of a monitoring device according to a second embodiment of the present invention on a furnace lid.

In the figure:

10. furnace cover 20, monitoring device 21 and cover body

22. Temperature measuring instrument 30, setting area 31, solid-liquid interface

40. A main furnace chamber 50, a guide cylinder 60 and a quartz crucible

70. Controller 80, heater 90, CCD camera

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The first embodiment is as follows:

the embodiment provides a single crystal furnace, which comprises a furnace cover 10 and a main furnace chamber 40, and is also provided with a plurality of monitoring devices 20 for monitoring the temperature in a set area 30 of the liquid level of molten silicon in a quartz crucible 60 of the main furnace chamber 40, as shown in figure 1, wherein the monitoring devices 20 are fixedly arranged on the inner side of the furnace cover 10 and are arranged obliquely above a guide cylinder 50 on the inner side of the main furnace chamber 40, and the monitoring devices 20 are all obliquely arranged towards the direction of the set area 30.

In this embodiment, two sets of monitoring devices 20 are provided, and the monitoring devices 20 are fixedly disposed on a side close to the upper end opening of the furnace cover 10 and symmetrically disposed on the inner wall of the furnace cover 10. The monitoring device 20 is at least offset from the CCD camera 90 arranged on the furnace lid 10 to prevent the fixed position thereof from being blocked by the CCD camera 90 and affecting the illumination angle of the monitoring device 20. Preferably, the monitoring device 20 and the CCD camera 90 are located on the same radial circumference, as shown in fig. 2, and the monitoring device 20 and the CCD camera 90 are arranged in a staggered manner, which not only can ensure that the monitoring area is not blocked by any foreign object, but also can clearly and more accurately monitor the temperature value of the molten silicon liquid level, and provide strong evidence for judging the temperature stabilizing effect. The monitoring device 20 provided on both sides can not only simultaneously monitor the temperature consistency of the opposite positions, but also prevent one from causing a problem and the other from monitoring the melt surface temperature.

Specifically, the monitoring device 20 includes a cover body 21 and a temperature measuring instrument 22 disposed inside the cover body 21, the cover body 21 is a groove body with an opening at the upper end, that is, only one end is open, and the other surfaces are all closed structures, and one side of the opening of the cover body 21 is disposed near the furnace cover 10, the structure of the temperature measuring instrument 22 of the cover body 21 is matched, and the inclination direction of the temperature measuring instrument 22 is matched with the inclination angle of the temperature measuring instrument 22. The cover body 21 is made of high-temperature-resistant glass materials, is transparent and heat-insulating and is not easy to crack, the temperature measuring instrument 22 can be better protected by the cover body 21, and impurities which are not beneficial to crystal growth and generated by high-temperature failure of the temperature measuring instrument 22 or melting of parts on the temperature measuring instrument 22 are prevented. The cover body 21 can be of a cylindrical structure or a cuboid structure, but one side of the cover body 21, which is far away from the furnace cover 10, can be of an arc structure or a plane structure, which is beneficial to the irradiation of infrared rays of the temperature measuring instrument 22. In this embodiment, the two monitoring devices 20 are both provided with an infrared thermometer 22, which is JTCSG2500, or CT1MHSF or CT2MHSF, and both have a wide temperature measurement range and high temperature measurement accuracy, and certainly, other types of thermometers 22 may be selected, which is not limited herein.

Further, the set region 30 is provided near the center of the surface of the molten silicon in the quartz crucible 60, and it is preferable that the set region 30 includes at least the solid-liquid interface 31 at the time of isodiametric pulling of the single crystal and the minimum distance of the set region 30 from the solid-liquid interface 31 at the time of isodiametric pulling is 0 to 15 mm. The temperature of the area at the middle position on the liquid surface of the molten silicon is lower than the temperature of the surrounding area close to the heater 80, and particularly when the temperature is stabilized for welding, the temperature of the solid-liquid interface 31 during welding needs to be ensured, so that the next seeding operation can be facilitated, dislocation can be better eliminated, and the success of crystal seeding can be ensured. Since the temperature measuring instrument 22 projects to the molten silicon liquid level to be a point in the set area 30, the temperature measuring point is only required to be ensured in the set area 30 in the temperature stabilizing process; when the equal-diameter operation is performed after the seeding is successful, the temperature measuring instrument 22 can also monitor the temperature of the region near the solid-liquid interface 31 during the equal diameter, particularly measure the temperature of the region around the solid-liquid interface 31 in the set region 30, and determine the temperature gradient temperature of the solid-liquid interface 31 during the equal diameter. The shape of the setting region 30 may be a circular structure, which is concentric with the projection circle of the crystal with equal diameter as shown in fig. 3, and the temperature measuring point of the temperature measuring instrument 22 only needs to be projected to the region between the crystal with equal diameter and the excircle of the setting region 30; the shape of the set area 30 may be elliptical, and as shown in fig. 4, the projected circle of the crystal having the same diameter is positioned inside the set area 30 and at the center thereof, and the temperature measurement point of the thermometer 22 may be projected into the areas outside the crystal and near both ends of the set area 30. The set areas 30 with the two structures can meet the monitoring of the temperature of the molten silicon liquid level by the temperature measuring instrument 22, and further can complete the temperature monitoring of the temperature stabilizing process of the pulled single crystal, thereby ensuring the pulling effect of the temperature stabilizing welding process and preparing for the next seeding process.

Further, the single crystal furnace also comprises a controller 70 arranged outside the single crystal furnace, and the controller 70 is used for receiving and processing temperature monitoring data sent by the temperature measuring instrument 22 in the monitoring device 20. The two thermometers 22 simultaneously and synchronously monitor the molten silicon liquid level, the measured data are simultaneously transmitted to the controller 70, the controller 70 processes the two groups of data, the average value of the two groups of data is obtained, then the two groups of data are compared with the temperature stabilizing temperature set by the standard, according to the comparison result, the controller 70 sends a signal to control the heater 80, so that the heating power of the heater 80 is adjusted, the molten silicon liquid level, particularly the liquid level in the set area 30, meets the standard temperature requirement, and further the purpose of stabilizing the temperature is achieved.

Specifically, the temperature stabilizing process for pulling the single crystal according to the single crystal furnace comprises the following steps:

when the measured average value is smaller than the standard value, the standard value of the temperature stabilization temperature is 1430-1475 ℃ in the embodiment. The controller 70 will perform the heating power raising operation of the heater 80, so that the actual power of the heater 80 is heated by the set temperature-raising coefficient, that is, after the actual power of the heater 80 is multiplied by the temperature-raising coefficient, the power of the heater 80 can be slowly adjusted, so that the heating power of the heater 80 is gradually raised until the average value of the liquid level temperature of the molten silicon measured by the temperature measuring instrument 22 is within the range of the standard value 1430 and 1475 ℃. Wherein the temperature rise coefficient is 1.2-1.5.

Further, when the measured average value is greater than the standard value 1430-1475 ℃, the controller 70 will decrease the heating power of the heater 80 and heat the actual power of the heater 80 with the set temperature-decreasing coefficient, that is, after the actual power of the heater 80 is multiplied by the temperature-decreasing coefficient, the power of the heater 80 can be slowly adjusted to gradually decrease the power of the heater 80 until the average value of the liquid level temperature of the molten silicon measured by the temperature measuring instrument 22 is within the standard value range. Wherein the temperature reduction coefficient is 0.5-0.7.

Example two:

as shown in fig. 5, compared with the first embodiment, the largest difference of the present embodiment is a monitoring device 20, and the monitoring device 20 is positioned at a position offset from the CCD camera 90 disposed on the furnace cover 10 and on the same radial circumference as the CCD camera 90, as shown in fig. 6. The cover 21 in the monitoring device 20 has the same structure as that in the first embodiment, and the illustration is omitted here, and the cover may have a cylindrical structure or a rectangular structure, but the side of the cover 21 away from the furnace cover 10 may have an arc structure or a planar structure, which is beneficial to the infrared light irradiation of the temperature measuring instrument 22. In this embodiment, the type of the infrared thermometer 22 is JTCSG2500, CT1MHSF, or CT2MHSF, which is the same as that in the first embodiment, but of course, other types of thermometers 22 may be selected, which is not limited herein.

In this embodiment, after the data measured by the single temperature measuring device 22 is transmitted to the controller 70, the controller 70 compares the received data with the temperature stabilizing temperature set by the standard, and then the controller 70 sends a signal to control the heater 80 according to the comparison result, so as to adjust the heating power of the heater 80 to make the liquid level of the molten silicon, especially the liquid level in the setting region 30, meet the standard temperature requirement, thereby achieving the purpose of stabilizing the temperature.

Specifically, the temperature stabilizing process for pulling the single crystal according to the single crystal furnace comprises the following steps:

when the measured single temperature test value is smaller than the standard value, the standard value of the temperature stabilizing temperature is still 1430-1475 ℃ in the embodiment. The controller 70 will perform the heating power raising of the heater 80, so that the actual power of the heater 80 is heated by the set temperature-raising coefficient, that is, after the actual power of the heater 80 is multiplied by the temperature-raising coefficient, the power of the heater 80 can be slowly adjusted, so that the heating power of the heater 80 is gradually raised until the temperature value of the molten silicon liquid level measured by the temperature measuring instrument 22 is within the range of the standard value 1430 and 1475 ℃. Wherein the temperature rise coefficient is still 1.2-1.5.

Further, when the measured single temperature test value is greater than the standard value 1430-. Wherein the temperature reduction coefficient is still 0.5-0.7.

In the embodiment, the purpose of monitoring the stable temperature and the constant temperature can be still achieved by adopting a group of monitoring devices to monitor the molten silicon liquid level, the structure is simple, the operation is easy, the safety and the reliability are realized, the automatic adjustment of the monitoring of the molten silicon liquid level temperature is realized, and the stability of the molten silicon liquid level temperature in the stable temperature drawing process is ensured.

Compared with the prior art, by adopting the technical scheme, the temperature of the molten silicon liquid level is automatically monitored and adjusted by setting the temperature of the molten silicon liquid level, particularly the temperature close to the central position, so that the temperature of a solid-liquid interface in a temperature-stabilizing drawing process is ensured to be transversely fixed, a foundation is laid for subsequent successful seeding, a monitoring area is reasonably set, the monitoring temperature is accurate and easy to control, and the automatic adjustment of the temperature of the molten silicon liquid level is realized; meanwhile, the temperature around the solid-liquid interface in the subsequent crystal drawing process can be monitored, so that the consistency of the growth temperature gradient of the single crystal can be ensured, and the production efficiency is improved.

The embodiments of the present invention have been described in detail, and the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.