Dislocation-free ending process of heavily doped red phosphorus silicon single crystal

Abstract

The invention discloses a dislocation-free ending process of a heavily doped red phosphorus silicon single crystal. The ending process comprises the steps that the ending process is divided into an earlier ending stage, a middle ending stage, a later ending stage and a final ending stage according to the ending length, and the earlier ending stage is controlled to grow in the shape with the ending angle being 50-60 degrees; in the ending middle stage, growing in a shape with an ending angle of 60-90 degrees; growing in a shape with an ending angle of 15-45 degrees in the later ending stage; growing in a shape with the ending angle of 75-90 degrees at the ending end, and controlling the temperature rise in a power increasing manner in the ending process. According to the dislocation-free ending process provided by the invention, the SOP parameters of the ending are reasonably proportioned and balanced, so that the ending is reduced according to a certain shape proportion, and the perfectness rate of the ending is increased to 90% or above.

Description

Technical Field

[0001] The invention relates to a dislocation-free finishing process for a heavily red-phosphorus-doped silicon single crystal, and belongs to the technical field of Czochralski silicon single crystal growth. Background Art

[0002] In recent years, the semiconductor market has maintained a growth momentum. Semiconductors will be more widely used in many fields such as artificial intelligence, computing infrastructure, automobiles, high-bandwidth memory and small chips. As one of the world's largest semiconductor markets, China's sales and output have shown strong growth momentum. Especially with the rapid development of the portable and wearable markets, the market demand for low-voltage devices has gradually increased due to their low power consumption and fast response speed.

[0003] Compared with MOS substrates, the on-resistance contribution of substrates for low-voltage devices is more prominent, and users are more looking forward to substrate materials with low resistivity. In order to ensure stable output and maximize the benefits of single crystal products, the finishing process in the single crystal production process is crucial. The main purpose of finishing is to prevent cracks and dislocations in the equal diameter part, which will lead to unqualified single crystals. In the finishing process, edge jamming, breaking, and crystallization will cause dislocations. As dislocations continue to climb, they will cause huge losses to the single crystal and have a huge impact on production capacity.

[0004] Therefore, the development of dislocation-free finishing process is urgent. Summary of the invention

[0005] The purpose of the present invention is to provide a dislocation-free finishing process for heavily doped red phosphorus silicon single crystals, which is particularly suitable for dislocation-free finishing of 8-inch heavily doped red phosphorus silicon single crystals in a thermal field equipped with a water-cooled heat shield. The finishing process can greatly improve the single crystal integrity rate.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A dislocation-free finishing process for heavily doped red phosphorus silicon single crystals, comprising: dividing the finishing process into an early finishing stage, a middle finishing stage, a late finishing stage and a final finishing stage according to the finishing length, wherein the early finishing stage is controlled to grow in a shape with a finishing angle of 50° to 60°; the middle finishing stage is controlled to grow in a shape with a finishing angle of 60° to 90°; the late finishing stage is controlled to grow in a shape with a finishing angle of 15° to 45°; the final finishing stage is controlled to grow in a shape with a finishing angle of 75°

[0008] The shape grows to 90°, and the temperature is controlled by increasing the power during the finishing process.

[0009] Preferably, the tail length in the range of 1-80 mm is the early stage of tailing; the tail length in the range of 60-140 mm is the middle stage of tailing; the tail length in the range of 120-200 mm is the late stage of tailing; and the tail length above 180 mm is the final stage of tailing.

[0010] Preferably, the target resistivity of the heavily red phosphorus-doped silicon single crystal is lower than 1 mΩ·cm, the target diameter is 8 inches or more, and the tail length is 240 mm or more.

[0011] The beneficial effects of the present invention are:

[0012] According to the dislocation-free finishing process provided by the present invention, the finishing SOP (standard operating procedure) parameters are reasonably proportioned and balanced, so that the finishing is reduced according to a certain shape ratio, and the finishing integrity rate will be increased to more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the temperature change curve controlled by the tail power method in the embodiment.

[0014] Figure 2 This is a physical picture of the full finishing ridge obtained in the embodiment.

[0015] Figure 3 This is a real picture of the blurred edges obtained in Comparative Example 1, where the picture in the upper right corner is an enlarged picture of the frame line.

[0016] Figure 4 This is the temperature change curve controlled by the tailing SP value method in Comparative Example 2.

[0017] Figure 5 This is the abnormal physical image obtained by using the ending SP value method in Comparative Example 2. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not intended to limit the protection scope of the present invention.

[0019] The dislocation-free finishing process of the heavily red phosphorus-doped silicon single crystal of the present invention mainly controls the temperature rise by increasing the power. By increasing the power and controlling the temperature rise, the diameter of the single crystal can be reduced, thinned, and shrunk to a point, and dislocations can be eliminated.

[0020] In the dislocation-free finishing process of the heavily doped red phosphorus silicon single crystal of the present invention, the finishing process is divided into the early stage of finishing, the middle stage of finishing, the late stage of finishing and the final stage of finishing according to the finishing length, and the tailing length is in the interval of 1-80mm for the early stage of finishing; the tailing length is in the interval of 60-140mm for the middle stage of finishing; the tailing length is in the interval of 120-200mm for the late stage of finishing; and the tailing length is above 180mm for the final stage of finishing. Given the optimized SOP parameters, the finishing is carried out regularly according to a certain shape: the early stage of finishing is controlled to grow in a shape with a finishing angle of 50° to 60°; the middle stage of finishing is grown in a shape with a finishing angle of 60° to 90°; the late stage of finishing is grown in a shape with a finishing angle of 15° to 45°; the final stage of finishing is grown in a shape with a finishing angle of 75° to 90°, and the power method (the way of increasing power) is used to control the temperature rise during the finishing process.

[0021] The tail angle is defined as the magnitude of the tail direction and the radial direction of the single crystal, and is represented by R. The early and middle stages of the tail should not be too fast. If the tail angle R < 50° is too early, the tail overheating edge will be scattered and there will be no obvious edge (such as Figure 2 This will greatly increase the risk of bud breakage at the end.

[0022] The traditional SP value method for controlling temperature rise is to use an SP thermometer to detect the temperature of the thermal field during the growth of the silicon single crystal, and then convert the SP value into power through calculation, so as to control the melt temperature and ensure the growth of the silicon single crystal. However, the temperature change in the finishing process of the present invention abandons the traditional SP value method to control the temperature rise, and instead uses the power method to control the temperature rise. The finishing shape will only change according to the set power trend, with good reproducibility, and the abnormality of SP only represents the abnormality of the numerical value. Using the finishing process of the present invention, the edges of the single crystals in the middle and final stages of the finishing are thick and full, and the intact rate is high.

[0023] The following is a comparative analysis of the improvements involved in the technical solution of the present invention through the embodiment and the comparative example, and the description of other operation processes and related parameter control during the single crystal pulling process is omitted. For the omitted content, it means that the operation and related parameter control performed in the embodiment and the comparative example are the same.

[0024] Example

[0025] The single crystal growth experiment uses a 110B direct-pull silicon single crystal furnace produced by Zhejiang Jingsheng Electromechanical Co., Ltd. This single crystal furnace is equipped with a 24-inch thermal field, a large-diameter water-cooled heat screen, and a maximum feed rate of 140kg. The silicon single crystal grown in the experiment is N-type, with a crystal orientation of <100> , the dopant is red phosphorus, the target resistivity is less than 1mΩ·cm, the target diameter is 8 inches, and the tail length is 240mm and above.

[0026] The finishing process of this embodiment is as follows: the power method is used to control the temperature rise during the finishing process. The power and casting speed change data are shown in Table 1. The actual power and SP value change curves at the end are as shown in Table 1. Figure 1 It should be noted that Figure 1 The SP setting value curve of the medium heat field coincides with the SP value of the heat field, and the main heating power output curve coincides with the main heating power measurement curve. Therefore, the SP setting value curve of the heat field and the main heating power output curve in the figure are not shown. The finishing process of this embodiment is adopted, and the power method is used to control the temperature. The power curve directly controls the shape of the single crystal. Therefore, the abnormality of the SP value has no effect and has no effect on the shape of the single crystal.

[0027] Table 1

[0028]

[0029] The final product picture obtained is as follows Figure 2 As shown, the angle grows in the shape of 50°~60° in the early stage of finishing; the angle grows in the shape of 60°~90° in the middle stage of finishing, and the angle grows in the shape of 15°~45° in the late stage of finishing; the angle grows in the shape of 75°~90° in the late stage of finishing. The edges of the single crystals in the middle and late stages of finishing are thick and full, and the intact rate is relatively high.

[0030] By adopting the finishing process method of the present invention, the finishing shape will only change according to the set power trend, and the replicability is good. Figure 1 As shown in the figure, the abnormality of SP only represents the abnormality of the value and will not affect the actual shape of the single crystal, which will greatly improve the consistency of the finishing shape. The finishing good rate of 108 single crystals in 3 months was summarized and it was found that the finishing good rate increased from 50% in comparative example 1 to 90.7%, and from 20% in comparative example 2 to 90.7%, and the finishing good rate was greatly improved.

[0031] Comparative Example 1

[0032] The single crystal growth experiment uses a 110B direct-pull silicon single crystal furnace produced by Zhejiang Jingsheng Electromechanical Co., Ltd. This single crystal furnace is equipped with a 24-inch thermal field, a large-diameter water-cooled heat screen, and a maximum feed rate of 140kg. The silicon single crystal grown in the experiment is N-type, with a crystal orientation of <100>, and the dopant is red phosphorus. The target resistivity is less than 1mΩ·cm, the target diameter is 8 inches, and the tail length is 240mm or more.

[0033] According to the traditional finishing process, the SP value is used to control the temperature rise during the finishing process. The changes in SP value and casting speed are shown in Table 2. The actual finishing picture is shown in Figure 3As shown, the shape of the finishing process is not important. The entire finishing process is reduced at a certain angle, and only a sharp shoulder appears at the end of the finishing. The disadvantage of this is that the finishing is overheated, and the edges change from thick and full to flat and wide. This is a manifestation of overheating during the finishing process, and the probability of broken buds at the finishing is significantly increased.

[0034] Table 2

[0035]

[0036] Comparative Example 2

[0037] The single crystal growth experiment uses a 110B direct-pull silicon single crystal furnace produced by Zhejiang Jingsheng Electromechanical Co., Ltd. This single crystal furnace is equipped with a 24-inch thermal field, a large-diameter water-cooled heat screen, and a maximum feed rate of 140kg. The silicon single crystal grown in the experiment is N-type, with a crystal orientation of <100> , the dopant is red phosphorus, the target resistivity is less than 1mΩ·cm, the target diameter is 8 inches, and the tail length is 240mm and above.

[0038] According to the traditional finishing process, the SP value is used to control the temperature rise during the finishing process. The SP value and the casting speed change are shown in Table 3. The actual finishing power and SP value change curve are shown in Figure 4 It should be noted that Figure 4 The main heating power output curve in the figure coincides with the main heating power measurement curve, so the main heating power output curve in the figure is not shown. In this comparative example, the SP value method is used to control the power, and the power controls the temperature and then controls the shape of the single crystal. Figure 4 As shown, when the SP value control reaches a certain SP value, an abnormality will occur, which will lead to power abnormality.

[0039] Table 3

[0040]

[0041] The temperature change in the finishing process is controlled by the SP value, and the power is indirectly controlled by the SP value. The disadvantage of SP control is that when the SP value reaches a certain peak value, it will be out of control, that is, the actual SP value change will not change according to the set trend, which will lead to power abnormality. Because the SP value drops sharply, the power increases, but the actual temperature rises untimely, which will lead to crystallization at the end of the finishing process. Figure 5 As shown in (a), in severe cases, Figure 5 As shown in (b), the tail shape is abnormal, which will definitely cause the tail to get stuck.

Claims

1. A dislocation-free finishing process for heavily red phosphorus-doped silicon single crystals, characterized in that: The finishing process includes: dividing the finishing process into an early finishing stage, a middle finishing stage, a late finishing stage and a final finishing stage according to the finishing length, wherein the early finishing stage is controlled to grow in a shape with a finishing angle of 50° to 60°; the middle finishing stage is controlled to grow in a shape with a finishing angle of 60° to 90°; the late finishing stage is controlled to grow in a shape with a finishing angle of 15° to 45°; the final finishing stage is controlled to grow in a shape with a finishing angle of 75° to 90°, and the temperature rise is controlled by increasing the power during the finishing process.

2. The dislocation-free finishing process of heavily red phosphorus-doped silicon single crystal according to claim 1, characterized in that: The tail length in the range of 1-80mm is the early stage of tailing; the tail length in the range of 60-140mm is the middle stage of tailing; the tail length in the range of 120-200mm is the late stage of tailing; the tail length above 180mm is the final stage of tailing.

3. The dislocation-free finishing process of heavily red phosphorus-doped silicon single crystal according to claim 1, characterized in that: The target resistivity of the heavily red phosphorus-doped silicon single crystal is less than 1 mΩ·cm, the target diameter is 8 inches or more, and the final length is 240 mm or more.

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