Thermal field device and crystal pulling method for increasing oxygen content of boron-doped high-speed single-crystal silicon

Abstract

The present invention provides a thermal field device and a crystal pulling method for improving the oxygen content of boron-doped high-pulling-speed single-crystal silicon, and relates to the technical field of single-crystal silicon pulling. The heat shield is located above the crucible, the lifting ring is located above the support ring, the support ring is located on the thermal insulation material part, the upper part of the heat shield is connected to the lifting ring, the lifting ring is detachably connected to the heat shield rope, the support ring is embedded in the thermal insulation material part, and there is a predetermined distance between the lifting ring and the support ring, so that argon gas can enter from the gap between the lifting ring and the support ring, forming a circulation in the furnace, which helps oxygen atoms in SiO in the quartz crucible to enter the crystal rod, so as to improve the oxygen content of the high-pulling-speed crystal rod.

Description

Technical Field

[0001] The invention belongs to the technical field of single crystal silicon pulling, and in particular relates to a thermal field device and a crystal pulling method for increasing the oxygen content of boron-doped high-pulling-speed single crystal silicon. Background Art

[0002] The oxygen content of the crystal rod is an important parameter in single crystal silicon. Oxygen atoms usually exist in the silicon lattice in an interstitial state. Oxygen atoms can pin dislocations in single crystal silicon and improve the mechanical strength of silicon wafers. In addition, the related defects generated by oxygen atoms, combined with the device process, can form internal impurities and remove metal impurities. Therefore, in the production of modern semiconductor-grade single crystal silicon, the oxygen content is usually controlled within the required range. Some product specifications require the required oxygen content for boron-doped high-pulling-speed single crystal silicon, but for boron-doped high-pulling-speed single crystal silicon, due to the excessively fast pulling speed, the oxygen atoms enter the crystal rod in a shorter time, resulting in a lower oxygen content. Summary of the invention

[0003] In view of this, the present invention provides a thermal field device for increasing the oxygen content of boron-doped high-pulling-rate single-crystalline silicon.

[0004] It is also necessary to provide a method for increasing the oxygen content of boron-doped high-pulling-rate single-crystal silicon.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A thermal field device for increasing the oxygen content of boron-doped high-pulling-rate single-crystal silicon comprises a crucible, a heating component, a heat-insulating material portion, and a heat shield rope, wherein the heating component is located at the bottom and side of the crucible, the heating component arranged at the side of the crucible is located between the crucible and the heat-insulating material portion, the heat-insulating material portion is located in the circumference of the crucible, the heat shield rope is located above the heat-insulating material portion, and also comprises an oxygen content increasing portion, the oxygen content increasing portion comprises a heat shield, a lifting ring, and a support ring, the heat shield is located above the crucible, the lifting ring is located above the support ring, the support ring is located on the heat-insulating material portion, the upper part of the heat shield is connected to the lifting ring, the lifting ring is detachably connected to the heat shield rope, the support ring is embedded in the heat-insulating material portion, and there is a predetermined distance between the lifting ring and the support ring to increase the oxygen content.

[0007] Preferably, the distance between the lifting ring and the supporting ring is 5 mm-30 mm.

[0008] Preferably, the thermal insulation material portion includes an upper thermal insulation material, a middle thermal insulation material, and a lower thermal insulation material, and the upper thermal insulation material, the middle thermal insulation material, and the lower thermal insulation material are arranged in sequence from top to bottom, the support ring is embedded in the top of the upper thermal insulation material, the bottom of the upper thermal insulation material is connected to one end of the middle thermal insulation material, and the other end of the middle thermal insulation material is connected to the lower thermal insulation material.

[0009] Preferably, the heating assembly comprises a bottom heater and a side heater, wherein the bottom heater is located at the bottom of the crucible, and the side heater is located between the crucible and the thermal insulation material portion to heat the crucible.

[0010] The method for crystal pulling using the thermal field device for increasing the oxygen content of boron-doped high-pulling-speed single-crystal silicon comprises a shoulder release step, a shoulder rotation step and a diameter equalization step performed in sequence, wherein:

[0011] In the shoulder release step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm;

[0012] In the shoulder turning step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm;

[0013] In the equal diameter step, the crystal rod pulling speed is 0.7-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-2.5 rpm, and the inert gas flow rate is 40-100 slm.

[0014] Preferably, the reactive gas is argon.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention provides a thermal field device for improving the oxygen content of boron-doped high-pulling speed single crystal silicon, wherein the heat shield is located above the crucible, the lifting ring is located above the support ring, the support ring is located on the thermal insulation material portion, the upper part of the heat shield is connected to the lifting ring, the lifting ring is detachably connected to the heat shield rope, the support ring is embedded in the thermal insulation material portion, and there is a predetermined distance between the lifting ring and the support ring, so that argon gas can enter from the gap between the lifting ring and the support ring, forming a circulation in the furnace, which helps the oxygen atoms in SiO in the quartz crucible to enter the crystal rod, so as to improve the oxygen content of the high-pulling speed crystal rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the thermal field device for increasing the oxygen content of boron-doped high-speed pulling single crystal silicon.

[0018] Figure 2 This is a schematic diagram of the structure of the thermal field in Comparative Example 1.

[0019] Figure 3The oxygen content results of Example 1 and Comparative Example 1 are shown in FIG.

[0020] Figure 4 It is a graph showing the crystallization rate results of Example 1 and Comparative Example 1.

[0021] In the figure: a thermal field device 10, a crucible 100, a heating assembly 200, a bottom heater 210, a side heater 220, a thermal insulation material portion 300, an upper thermal insulation material 310, a middle thermal insulation material 320, a lower thermal insulation material 330, a heat shield rope 400, an oxygen content increasing portion 500, a heat shield 510, a lifting ring 520, and a support ring 530. DETAILED DESCRIPTION

[0022] The technical solutions and technical effects of the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings of the present invention.

[0023] A thermal field device 10 for increasing the oxygen content of boron-doped high-pulling-rate single-crystal silicon comprises a crucible 100, a heating component 200, a heat-insulating material portion 300, and a heat shield rope 400, wherein the heating component 200 is located at the bottom and side of the crucible 100, the heating component 200 disposed at the side of the crucible 100 is located between the crucible 100 and the heat-insulating material portion 300, the heat-insulating material portion 300 is located in the circumference of the crucible 100, the heat shield rope 400 is located above the heat-insulating material portion 300, and is characterized in that: it also comprises an oxygen content increasing portion 500, the oxygen content The lifting part 500 includes a heat shield 510, a lifting ring 520, and a support ring 530. The heat shield 510 is located above the crucible 100, the lifting ring 520 is located above the support ring 530, and the support ring 530 is located on the thermal insulation material part 300. The upper part of the heat shield 510 is connected to the lifting ring 520, and the lifting ring 520 is detachably connected to the heat shield rope 400. The support ring 530 is embedded in the thermal insulation material part 300, and there is a predetermined distance between the lifting ring 520 and the support ring 530 to increase the oxygen content.

[0024] Specifically, the lifting ring 520 and the heat shield rope 400 are detachably connected via a Z-shaped plate.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention provides a thermal field device 10 for improving the oxygen content of boron-doped high-pulling-speed single-crystal silicon, wherein the heat shield 510 is located above the crucible 100, the lifting ring 520 is located above the support ring 530, the support ring 530 is located on the thermal insulation material portion 300, the upper portion of the heat shield 510 is connected to the lifting ring 520, the lifting ring 520 is detachably connected to the heat shield rope 400, the support ring 530 is embedded in the thermal insulation material portion 300, and there is a predetermined distance between the lifting ring 520 and the support ring 530, so that argon gas can enter from the gap between the lifting ring 520 and the support ring 530, forming a circulation in the furnace, which helps the oxygen atoms in SiO in the quartz crucible 100 to enter the crystal rod, so as to improve the oxygen content of the high-pulling-speed crystal rod.

[0027] Furthermore, the spacing between the lifting ring 520 and the supporting ring 530 is 5mm-30mm. If the spacing is too small, it is easy to cause the local airflow to increase, so that the uniformity of the oxygen atom concentration and temperature in different parts is reduced; if the spacing is too large, it is easy to increase the airflow flow space and generate turbulence, disrupting the stability of the gas environment in the furnace.

[0028] Furthermore, the thermal insulation material part 300 includes an upper thermal insulation material 310, a middle thermal insulation material 320, and a lower thermal insulation material 330, and the upper thermal insulation material 310, the middle thermal insulation material 320, and the lower thermal insulation material 330 are arranged in sequence from top to bottom, and the support ring 530 is embedded in the top of the upper thermal insulation material 310, and the bottom of the upper thermal insulation material 310 is connected to one end of the middle thermal insulation material 320, and the other end of the middle thermal insulation material 320 is connected to the lower thermal insulation material 330 to prevent the upper thermal insulation material 310 from oxidizing and affecting the strength.

[0029] Preferably, the heating assembly comprises a bottom heater 210 and a side heater 220 , wherein the bottom heater 210 is located at the bottom of the crucible, and the side heater 220 is located between the crucible and the thermal insulation material portion 300 , so as to heat the crucible.

[0030] The method for pulling a crystal using the thermal field device 10 for increasing the oxygen content of a boron-doped high-pulling-rate single-crystal silicon comprises a shoulder-releasing step, a shoulder-turning step and a diameter-equalizing step performed in sequence, wherein:

[0031] In the shoulder release step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible 100 rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm;

[0032] In the shoulder turning step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible 100 rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm;

[0033] In the equal diameter step, the crystal rod pulling speed is 0.7-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the rotation speed of the crucible 100 is 0.8-2.5 rpm, and the flow rate of the inert gas is 40-100 slm.

[0034] Furthermore, the active gas is argon.

[0035] Specifically, argon gas enters through the gap between the lifting ring 520 and the support ring 530, forming a circulation in the furnace, inhibiting the oxygen generated by crystal rotation and crucible rotation convection from being transmitted to the free liquid surface, allowing the oxygen generated by convection to be transmitted to the growth interface, and enters the crystal rod through segregation to become interstitial oxygen, and reducing the amount of argon gas directly carrying away the volatilized SiO, which helps the oxygen atoms in the SiO in the quartz crucible 100 to enter the crystal rod, so as to increase the oxygen content of the high-pulling speed crystal rod. Embodiment 1:

[0036] Use 2408S2 single crystal furnace, use Figure 1 In the heat field 10 shown, the gap between the lifting ring 520 and the supporting ring 530 is 5-20 mm, and an 8-inch boron-doped single crystal is grown. Seed crystal: 100 seed crystals, feed amount 150-200 kg, doping amount 5-10 g (resistivity range 10-20 Ω·cm). Argon 50-80 slm, furnace pressure 10-15 kpa, crucible rotation 1-1.5 rpm, crystal rotation 10-15 rpm, pulling speed 1-1.5 mm / min, crystal pulling, obtain crystal rod, experiment twice, the crystal rod oxygen content detection, the results are as follows Figure 3 As shown, and the crystal ingot crystallization rate is Figure 4 shown.

[0037] Comparative Example 1:

[0038] Use 2408S2 single crystal furnace, use Figure 2 The thermal field shown in the figure, the gap between the lifting ring 520 and the supporting ring 530 is 0mm, and the other parts are the same as those in Example 1. An 8-inch boron-doped single crystal is grown, with 100 seed crystals, 150-200Kg of feed, and 5-10g of doping (resistivity range 10-20Ω·cm). Argon gas 50-80slm, furnace pressure 10-15kpa, crucible rotation 2-2.5rpm, crystal rotation 10-15rpm, pulling speed 1-1.5mm / min, and crystal pulling to obtain a crystal rod. The experiment was conducted twice, and the oxygen content of the crystal rod was tested, and the results were as follows Figure 3 As shown, and the crystal ingot crystallization rate is Figure 4 shown.

[0039] Comparative Example 2:

[0040] Use 2408S2 single crystal furnace, use Figure 2 The thermal field shown is the same as that of the first embodiment. The gap between the lifting ring 520 and the supporting ring 530 is 0 mm. An 8-inch boron-doped single crystal is grown. Seed crystal: 100 seed crystals, feed amount 150-200 kg, doping amount 5-10 g (resistivity range 10-20 Ω·cm). Argon 50-80 slm, furnace pressure 10-15 kpa, crucible rotation 1-1.5 rpm, crystal rotation 10-15 rpm, pulling speed 1-1.5 mm / min, crystal pulling, and crystal rods are obtained. The experiment is repeated twice, and the oxygen content of the crystal rod is tested. The results are as follows Figure 3 As shown, and the crystal ingot crystallization rate is Figure 4 shown.

[0041] Depend on Figure 3 , Figure 4 It can be seen that by changing the thermal field structure in combination with high pulling speed and related parameters, the average level of Oi is significantly improved to about 15.4ppma, which can meet the requirements of high oxygen specifications. After changing the structure of the heat shield 510, there is no effect on the thermal field temperature, avoiding deformation and distortion due to low temperature that affects the crystallization rate, making the crystallization rate of the crystal rod stable and not prone to equal diameter ending NG.

[0042] 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 increasing the oxygen content of boron-doped high-pulling-rate single crystal silicon, using a thermal field device for increasing the oxygen content of boron-doped high-pulling-rate single crystal silicon to pull a crystal rod, the thermal field device comprising a crucible, a heating component, a heat-insulating material portion, and a heat shield rope, the heating component is located at the bottom and side of the crucible, the heating component arranged on the side of the crucible is located between the crucible and the heat-insulating material portion, the heat-insulating material portion is located in the circumference of the crucible, and the heat shield rope is located above the heat-insulating material portion, characterized in that: It includes a shoulder release step, a shoulder rotation step and a diameter equalization step performed sequentially, wherein: In the shoulder release step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm; In the shoulder turning step, the crystal rod pulling speed is 1.2-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-1.5 rpm, and the inert gas flow rate is 40-100 slm; In the equal diameter step, the crystal rod pulling speed is 0.7-2 mm / min, the furnace pressure is 5-15 KPa, the crystal rod rotation speed is 10-20 rpm, the crucible rotation speed is 0.8-2.5 rpm, and the inert gas flow rate is 40-100 slm; The thermal field device also includes an oxygen content increasing part, which includes a heat shield, a lifting ring, and a support ring. The heat shield is located above the crucible, the lifting ring is located above the support ring, and the support ring is located on the thermal insulation material part. The upper part of the heat shield is connected to the lifting ring, and the lifting ring is detachably connected to the heat shield rope. The support ring is embedded in the thermal insulation material part. There is a predetermined distance between the lifting ring and the support ring, so that gas can enter from the gap between the lifting ring and the support ring to form a circulation in the furnace, which helps oxygen atoms in SiO2 in the quartz crucible to enter the crystal rod to increase the oxygen content. The distance between the lifting ring and the supporting ring is 5mm-30mm.

2. The method for increasing the oxygen content of boron-doped high-pulling-rate single crystal silicon according to claim 1, characterized in that: The thermal insulation material portion includes an upper thermal insulation material, a middle thermal insulation material, and a lower thermal insulation material, which are arranged in sequence from top to bottom, and the support ring is embedded in the top of the upper thermal insulation material, the bottom of the upper thermal insulation material is connected to one end of the middle thermal insulation material, and the other end of the middle thermal insulation material is connected to the lower thermal insulation material.

3. The method for increasing the oxygen content of boron-doped high-pulling-rate single crystal silicon according to claim 1, characterized in that: The heating assembly comprises a bottom heater and a side heater. The bottom heater is located at the bottom of the crucible, and the side heater is located between the crucible and the thermal insulation material portion to heat the crucible.

4. The method for increasing the oxygen content of boron-doped high-pulling-rate single crystal silicon according to claim 1, characterized in that: The inert gas is argon.

Images