Positioning device and positioning method for equal-diameter starting point of czochralski crystal

Abstract

The invention belongs to the field of crystal processing and manufacturing, and provides a positioning device and a positioning method for an equal-diameter starting point of a czochralski crystal. The positioning device comprises an auxiliary shell and a positioning piece, the auxiliary shell is provided with a top plate and a side plate connected with the top plate, an open crystal containing space is formed, the crystal containing space can be conveniently placed on a crystal to form support, and platform support is provided for follow-up measuring. The positioning sheet is connected to the top plate in parallel, and the length of the positioning sheet is enough to cross the central axis of the crystal, so that the thin neck of the crystal can be conveniently positioned and flush with the position. The equal-diameter starting point can be measured by taking the positioning sheet at the flush position as an initial measurement point and combining with the length data of the shoulder part of the crystal in the crystal growth and manufacturing process of the czochralski method. By means of the positioning device, the position of the isometric starting point can be conveniently, rapidly and accurately obtained, and the influence caused by positioning errors is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal manufacturing, and relates to a positioning device and a positioning method for equal-diameter starting points of a Czochralski crystal. Background Art

[0002] As an important semiconductor material, single crystal silicon plays a pivotal role in the electronics industry. High-purity single crystal silicon can be made into diodes, triodes, thyristors and various integrated circuits (such as chips and CPUs in computers). It can also be used to manufacture photovoltaic devices such as solar photovoltaic cells to convert radiation energy into electrical energy.

[0003] The growth and manufacturing of single crystal silicon mainly relies on a series of purification and crystal growth processes starting from polycrystalline silicon raw materials. First, the low-purity silicon raw materials are purified to high-purity polycrystalline silicon by chemical methods. Then, under specific equipment and process conditions, the polycrystalline silicon raw materials are melted and single crystal silicon is grown by controlling the solidification process. According to the specific growth technology and conditions, single crystal silicon can be classified according to different methods, such as Czochralski method, zone melting method and epitaxy method.

[0004] Among them, the Czochralski method, as one of the main methods for growing single crystal silicon, has the advantages of high precision, high productivity, flexibility and doping ability. The growth process of the Czochralski method usually includes seeding, shoulder release, shoulder rotation, equal diameter and finishing stages, such as Figure 1 As shown in the figure, a head (including a thin neck and a shoulder), a crystal equal diameter part and a crystal tail are formed, thereby obtaining a single crystal silicon rod with a conical head and tail and a cylindrical middle section. Among them, the middle section cylindrical part grown in the equal diameter stage is mainly used for further processing into silicon wafers.

[0005] Before further processing the single crystal silicon rod into silicon wafers, it is necessary to locate the starting point of the equal diameter stage, so as to determine the position of subsequent crystal segment cutting and sampling. The current common methods include visually obtaining the position of the beginning of the ridgeline as the starting point of the equal diameter stage, or using an inner diameter fixture with a preset size that matches the equal diameter stage to determine it. However, the position of the beginning of the ridgeline, the diameter of the shoulder to the diameter at the beginning of the equal diameter will be affected by the actual process of shoulder release and shoulder turning, resulting in the inability of the existing methods that directly measure the starting point of the equal diameter to accurately locate the starting point of the equal diameter. This position error, on the one hand, will cause some usable parts to be discarded during the processing process, resulting in serious waste, increasing costs and affecting the final output. On the other hand, it is also easy to mislead the subsequent process control, thereby affecting the quality of the resulting silicon wafers.

[0006] Therefore, it is still necessary to develop new positioning schemes to accurately determine the equal-diameter starting point of the Czochralski crystal and lay a solid foundation for subsequent processes. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a positioning device and a positioning method for the equal-diameter starting point of a Czochralski crystal. The positioning device includes an auxiliary shell and a positioning piece. The auxiliary shell has a top plate and a side plate connected to the top plate, forming an open crystal accommodating space, so that it is placed on the crystal to form a support, and also provides a platform support for subsequent measurement. The positioning piece is connected in parallel to the top plate, and its length is sufficient to cross the central axis of the crystal, so that it is convenient to use positioning to position the thin neck of the crystal and make it flush with the position. By using the positioning piece in the flush position as the initial measurement point, combined with the crystal shoulder length data in the Czochralski crystal growth and manufacturing process, the equal-diameter starting point can be measured. The positioning device can be used to conveniently, quickly and accurately obtain the position of the equal-diameter starting point, avoiding the influence of positioning errors.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a positioning device for equal diameter starting points of a Czochralski crystal, comprising:

[0010] The auxiliary shell has a top plate and a side plate connected to the top plate to form an open crystal accommodating space; the side plate has a contact area that contacts with the equal diameter portion of the crystal to support the positioning device to be placed on the Czochralski crystal;

[0011] The positioning piece is parallel to the top plate, and has a connection end connected to the top plate and an opposite positioning end; the positioning piece has a length that allows the positioning end to cross the central axis of the crystal.

[0012] The starting point of the equal-diameter portion of a Czochralski crystal (or crystal rod) such as a single crystal silicon rod is usually difficult to determine accurately, and the existing solutions of directly visually observing or using a fixture to directly locate the equal-diameter starting point have large errors. The main idea of ​​the present invention is to deduce the actual position of the equal-diameter starting point through the relatively easy and accurate determination of the shoulder starting point and related data records (data during the growth and manufacturing process). Therefore, a specially designed positioning device is used to determine the shoulder starting point on the Czochralski crystal as the initial measurement point, and then the corresponding position of the equal-diameter starting point can be accurately found. The use of this positioning device can accurately locate the equal-diameter starting point of the Czochralski crystal, thereby reducing processing losses, and is also conducive to accurately locating the position of subsequent samples (silicon wafers, etc.) and improving quality control capabilities.

[0013] It should be noted that the shoulder release starting point is the critical point where the crystal neck begins to grow. It has a large size mutation compared to the crystal neck and is therefore easier to determine.

[0014] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] As a preferred technical solution of the present invention, the auxiliary shell has a first top plate, a first side plate and a second side plate, and the top plate, the first side plate and the second side plate are perpendicular to each other and have a common vertex.

[0016] As a preferred technical solution of the present invention, the positioning piece is rotatable around the connecting end.

[0017] As a preferred technical solution of the present invention, the positioning end of the positioning plate has a positioning hole; and the diameter of the positioning hole is the same as the cross-sectional diameter of the shoulder starting point of the crystal; in the orthographic projection to the plane where the top plate is located, the distance from the center of the positioning hole to the contact area is equal to the cross-sectional radius of the equal-diameter part of the crystal.

[0018] In the present invention, the distance from the center of the positioning hole to the contact area is equal to the cross-sectional radius of the equal-diameter portion of the crystal, that is, the length of the positioning plate is ensured to ensure that the center of the positioning hole is sufficient to coincide with the central axis of the crystal, so that the thin neck of the crystal can pass through the positioning hole while the side plate can still be stably placed on the equal-diameter portion of the crystal.

[0019] As a preferred technical solution of the present invention, the material of the auxiliary shell includes polypropylene plastic; the material of the positioning piece includes hard metal.

[0020] As a preferred technical solution of the present invention, the positioning device also includes a ruler, which is perpendicular to the positioning piece and is arranged on the auxiliary shell. The initial scale end is flush with the positioning piece, and the maximum scale end extends in a direction away from the positioning piece until the maximum scale is greater than the length of the crystal head.

[0021] As a preferred technical solution of the present invention, the ruler is arranged on the side plate.

[0022] In a second aspect, the present invention provides a method for positioning an equal-diameter starting point of a Czochralski crystal, using the positioning device described in the first aspect, the positioning method comprising the following steps:

[0023] (1) Providing a Czochralski crystal with a thin crystal neck; obtaining shoulder length data and shoulder rotation length data of the Czochralski crystal during the growth and manufacturing process;

[0024] (2) placing the auxiliary shell on the equal diameter portion of the crystal on the Czochralski crystal, so that the top plate faces the crystal head and is perpendicular to the central axis of the crystal, and the side plates are in contact with the equal diameter portion of the crystal to support the positioning device;

[0025] (3) The positioning device is translated so that the positioning end of the positioning piece is flush with the starting point of the shoulder of the crystal;

[0026] (4) The position of the positioning piece is used as the initial measurement point, and the shoulder release length data and the shoulder rotation length data are combined to obtain the equal diameter starting point.

[0027] Since the positioning device and positioning method of the present invention rely on the starting point of shoulder release, when the crystal neck of the crystal is cut off during the seeding stage after the crystal is crystallized by the Czochralski method, a part of the crystal neck needs to be retained at the position where the size of the crystal neck changes suddenly, that is, before the starting point of the shoulder release stage, to facilitate subsequent positioning.

[0028] The shoulder length data and shoulder rotation length data in the present invention refer to the data recorded and saved in the crystal growth automation control system, which can be directly read and obtained. Add the shoulder length and shoulder rotation length, and measure the corresponding length from the positioning piece backwards. The position at this time is the precise equal diameter starting point position of the crystal.

[0029] As a preferred technical solution of the present invention, in the positioning device, the positioning end of the positioning plate has a positioning hole, and step (3) of the positioning method includes moving the positioning device in a translational manner so that the narrow neck of the Czochralski crystal passes through the positioning hole, and until the positioning hole stops at the starting point of the shoulder of the crystal and is flush with it.

[0030] As a preferred technical solution of the present invention, the positioning device also includes a ruler, and step (4) of the positioning method includes taking the position of the positioning piece as the initial measurement point, making the initial scale end of the ruler flush with the positioning piece, and sequentially accumulating the shoulder release length data and the shoulder rotation length data, and the position corresponding to the obtained final scale is the equal diameter starting point.

[0031] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0032] The present invention adopts a specially designed positioning device, which is placed on the crystal through an auxiliary shell support, and determines the position of the shoulder release starting point through a positioning piece, and combines the data in the Czochralski growth manufacturing process to measure and infer the actual position of the equal diameter starting point. The positioning device can accurately locate the equal diameter starting point of the Czochralski crystal, avoiding the influence of the positioning error caused by the visual method of the prior art, and is conducive to reducing processing losses, increasing production and reducing costs, and is also conducive to accurately locating the position of subsequent samples (silicon wafers, etc.) and improving the quality control ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of a Czochralski crystal.

[0034] Figure 2 It is a schematic structural diagram of the positioning device of Example 1 along the viewing direction of the first top plate.

[0035] Figure 3 It is a schematic structural diagram of the positioning device of Example 1 along the viewing direction of the first side panel.

[0036] Figure 4 It is a schematic diagram of a method for positioning the equal-diameter starting point of a Czochralski crystal using the positioning device of Example 1.

[0037] Figure 1-4 In the middle, S1-crystal head, S 11 - Crystalline neck, S 12- Crystal shoulder, S2-crystal equal diameter part, S3-crystal tail, L1-shoulder length, L2-shoulder rotation length, A-shoulder release starting point, B-shoulder rotation starting point, C-equal diameter starting point; 10-auxiliary shell, 11-first side plate, 12-second side plate, 13-first top plate, 20-positioning plate, 30-ruler.

[0038] Figure 5 This is an actual measurement diagram of the method for positioning the equal-diameter starting point of the Czochralski crystal using the positioning device of Example 1.

[0039] Figure 6 This is a schematic diagram of the ridge lines observed by visual inspection of the control group 1.

[0040] Figure 7 Schematic diagram of the structure of the clamp of control group 2.

[0041] Figure 8 This is a schematic diagram of the method for positioning the equal-diameter starting point of the Czochralski crystal using the fixture of control group 2.

[0042] Figure 7 In the figure, W1 is the inner diameter of the frame, and W2 is the depth of the frame. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0044] It should be clear to those skilled in the art that the embodiments are only intended to help understand the present invention and should not be considered as specific limitations of the present invention.

[0045] The Czochralski crystal of the present invention is as follows Figure 1 As shown, the Czochralski crystal includes a crystal head S1, a crystal equal diameter portion S2 and a crystal tail S3, wherein the crystal head S1 includes a crystal neck S 11 And crystal shoulder S 12 , the crystal shoulder S 12The crystal has a shoulder release starting point A and a shoulder rotation starting point B, and the crystal equal diameter portion S2 has an equal diameter starting point C. The shoulder release length is recorded as L1, and the shoulder rotation length is recorded as L2.

[0046] Example 1

[0047] This embodiment provides a positioning device for the equal diameter starting point of a Czochralski crystal, such as Figure 2 and Figure 3 As shown, including:

[0048] The auxiliary shell 10 comprises a first top plate 13, a first side plate 11 and a second side plate 12, wherein the first top plate 13, the first side plate 11 and the second side plate 12 are perpendicular to each other and have a common vertex, forming an open crystal accommodating space; the first side plate 11 and the second side plate 12 both have a contact area where the equal diameter parts S2 of the crystal contact each other, so as to support the positioning device to be placed on the Czochralski crystal; the material of the auxiliary shell 10 comprises polypropylene plastic (acrylic); the first side plate 11 and the second side plate 12 are rectangles of 150 mm×500 mm, sharing a long side; the first top plate 13 is a square of 150 mm×150 mm, with one corner cut off according to the right angle side length of an isosceles right trapezoid of 75 mm, and the remaining three corners are retained, wherein the vertex of one corner is the common vertex;

[0049] The positioning piece 20 is parallel to the first top plate 13, and has a connection end connected to the first top plate 13, and an opposite positioning end; the positioning piece 20 is rotatable around the connection end; the positioning piece 20 has a length that allows the positioning end to pass over the central axis of the crystal; the material of the positioning piece 20 includes hard metal stainless steel; the positioning piece 20 is connected to the first top plate 13 at a position where a corner is cut off by a screw and a nut through a hole, so that the positioning piece 20 is rotatable;

[0050] The ruler 30 is perpendicular to the positioning piece 20 and is disposed on the first side plate 11 of the auxiliary shell 10. The initial scale end is flush with the positioning piece 20, and the maximum scale end extends in a direction away from the positioning piece 20 until the maximum scale is greater than the length of the crystal head S1.

[0051] The positioning device for the equal-diameter starting point of the Czochralski crystal provided in this embodiment is suitable for processing single crystal silicon rods into 12-inch silicon wafers (the cross-sectional diameter of the equal-diameter part is preset to 300 mm). For single crystal silicon rods processed into silicon wafers of other sizes and different diameters, the positioning device can be applied after being appropriately scaled.

[0052] This embodiment also provides a method for locating the equal-diameter starting point of a Czochralski crystal, comprising:

[0053] (1) Provide a crystal neck S 11 A Czochralski crystal is obtained, and the shoulder length L1 data and the shoulder length L2 data of the Czochralski crystal during the growth and manufacturing process are obtained, the shoulder length L1 is 103.3 mm, and the shoulder length L2 is 25.2 mm;

[0054] (2) Figure 5 As shown, using the positioning device, the auxiliary shell 10 is placed on the crystal equal diameter portion S2 on the Czochralski crystal, so that the first top plate 13 faces the crystal head S1 and is perpendicular to the crystal center axis, and the first side plate 11 and the second side plate 12 are both in contact with the crystal equal diameter portion S2 to support the positioning device;

[0055] (3) The positioning device is translated so that the positioning end of the positioning piece 20 is flush with the shoulder starting point A of the crystal, as shown in FIG. Figure 4 As shown;

[0056] (4) Take the position of the positioning piece 20 as the initial measurement point, make the initial scale end of the ruler 30 (initial scale is 0 mm) flush with the positioning piece 20, and measure the shoulder length L1 data and the shoulder length L2 data in sequence. The position corresponding to the final scale of 128.5 mm is the equal diameter starting point C.

[0057] Control group 1

[0058] This control group provides a method for locating the equal diameter starting point of the Czochralski crystal. This method uses visual observation to take the starting point of the ridge between the shoulder part and the equal diameter part as the equal diameter starting point, such as Figure 6 The area pointed by the arrow.

[0059] Since crystals tend to expand preferentially on the crystal plane with the densest atomic arrangement, the crystals grown by the Czochralski method will form small planes on the shoulders and converge into a characteristic ridgeline at the beginning of equal diameter. In the current processing method, for convenience, the starting point of the ridgeline is often used as the starting point of equal diameter. However, the starting point of the ridgeline is not the real starting point position of equal diameter. By testing multiple Czochralski crystals, the current positioning method used in the control group 1 and the real starting point position of equal diameter determined by the positioning method of Example 1 of the present invention are compared. The deviation is shown in Table 1 (unit: mm). It can be seen that the starting point position of the ridgeline is more backward (biased to the tail of the crystal) than the real starting point position of equal diameter.

[0060] Table 1

[0061]

[0062]

[0063] Control group 2

[0064] This control group provides a method for locating the equal diameter starting point of a Czochralski crystal. This method uses a fixture to directly measure the equal diameter starting point, such as Figure 7 As shown, the fixture includes a frame with an opening, the inner diameter W1 of the frame is equal to the diameter of the cross section of the equal diameter part of the crystal, and the depth W2 of the frame is greater than the length of the crystal head.

[0065] The positioning method includes: moving the opening of the frame toward the crystal head, and inserting the crystal head into the frame until the frame is locked on the crystal, such as Figure 8 As shown, the position of the edge of the frame at this time is used as the starting point of equal diameter.

[0066] However, the disadvantage of the method of control group 2 is that when the cross-sectional diameter of the actual equal-diameter portion of the crystal at the initial stage deviates from the target preset value, the fixture cannot determine the correct position of the equal-diameter starting point based on the locking position. Specifically, due to the differences in the shoulder release and shoulder rotation processes, in practice, there is often a situation where the diameter of the equal-segment portion at the beginning does not reach the target preset diameter. At this time, the position of the equal-diameter starting point determined by the fixture will be biased backward (biased towards the tail of the crystal); and if the diameter of the equal-diameter portion at the beginning has exceeded the target preset diameter, the position of the equal-diameter starting point determined by the fixture will be biased forward (biased towards the head of the crystal). In addition to the process settings, the diameter of the equal-diameter at the initial stage in the actual production process will be affected by many other factors. Therefore, this method often cannot find the correct and accurate position of the equal-diameter starting point.

[0067] The use of the positioning device and positioning method described in the present invention can avoid the above problems. The shoulder starting point is found as the initial measurement point through the cooperation of the auxiliary shell and the positioning piece. The actual position of the equal diameter starting point can be accurately found by reading the recorded and saved shoulder length, thus avoiding the influence of positioning error. The method is simple, convenient and fast, which is beneficial to reducing processing loss. It is also beneficial to accurately locate the position of subsequent samples (silicon wafers, etc.) and improve the quality control capability.

[0068] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0070] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A positioning device for equal diameter starting points of Czochralski crystals, characterized in that: include: An auxiliary shell having a top plate and a side plate connected to the top plate to form an open crystal accommodating space; The side plate has a contact area that contacts the equal diameter portion of the crystal to support the positioning device to be placed on the Czochralski crystal; The positioning piece is parallel to the top plate, and has a connection end connected to the top plate and an opposite positioning end; the positioning piece has a length that allows the positioning end to cross the central axis of the crystal.

2. The positioning device for equal diameter starting points of Czochralski crystal according to claim 1, characterized in that: The auxiliary shell has a first top plate, a first side plate and a second side plate, wherein the top plate, the first side plate and the second side plate are perpendicular to each other and have a common vertex.

3. The positioning device for equal diameter starting points of Czochralski crystal according to claim 1 or 2, characterized in that: The positioning piece is rotatable around the connecting end.

4. The positioning device for equal diameter starting points of Czochralski crystals according to any one of claims 1 to 3, characterized in that: The positioning end of the positioning plate has a positioning hole; and the diameter of the positioning hole is the same as the cross-sectional diameter of the shoulder starting point of the crystal; in the orthographic projection to the plane where the top plate is located, the distance from the center of the positioning hole to the contact area is equal to the cross-sectional radius of the equal-diameter part of the crystal.

5. The positioning device for equal diameter starting points of Czochralski crystals according to any one of claims 1 to 4, characterized in that: The material of the auxiliary shell includes polypropylene plastic; the material of the positioning piece includes hard metal.

6. The positioning device for equal diameter starting points of Czochralski crystals according to any one of claims 1 to 5, characterized in that: The positioning device also includes a ruler, which is perpendicular to the positioning piece and is arranged on the auxiliary shell. The initial scale end is flush with the positioning piece, and the maximum scale end extends in a direction away from the positioning piece until the maximum scale is greater than the length of the crystal head.

7. The positioning device for equal diameter starting points of Czochralski crystal according to claim 6, characterized in that: The measuring ruler is arranged on the side plate.

8. A method for locating the equal-diameter starting point of a Czochralski crystal, characterized in that: Using the positioning device according to any one of claims 1 to 7, the positioning method comprises the following steps: (1) Providing a Czochralski crystal with a thin crystal neck; obtaining shoulder length data and shoulder rotation length data of the Czochralski crystal during the growth and manufacturing process; (2) placing the auxiliary shell on the equal diameter portion of the crystal on the Czochralski crystal, so that the top plate faces the crystal head and is perpendicular to the central axis of the crystal, and the side plates are in contact with the equal diameter portion of the crystal to support the positioning device; (3) The positioning device is translated so that the positioning end of the positioning piece is flush with the starting point of the shoulder of the crystal; (4) The position of the positioning piece is used as the initial measurement point, and the shoulder release length data and the shoulder rotation length data are combined to obtain the equal diameter starting point.

9. The method for locating equal-diameter starting points of a Czochralski crystal according to claim 8, characterized in that: In the positioning device, the positioning end of the positioning plate has a positioning hole, and step (3) of the positioning method includes moving the positioning device in a translational manner so that the narrow neck of the crystal passes through the positioning hole, and until the positioning hole stops at the shoulder starting point of the crystal and is flush with it.

10. The method for locating equal-diameter starting points of a Czochralski crystal according to claim 8 or 9, characterized in that: The positioning device also includes a ruler, and step (4) of the positioning method includes taking the position of the positioning piece as the initial measurement point, making the initial scale end of the ruler flush with the positioning piece, and sequentially accumulating the shoulder length data and the shoulder length data, and the position corresponding to the final scale is the equal diameter starting point.

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