Connecting device for stable operation of inner shaft of zone melting furnace

Abstract

The invention discloses a connecting device for stable operation of an inner shaft of a zone melting furnace. The connecting device is arranged in a gap between the lower end of an inner shaft of the zone melting furnace and the inner wall of an outer shaft and comprises a pressure bearing, a needle bearing, a bearing spacer ring, a bearing sleeve, a bearing gland, a clamp spring and a positioning sleeve, the needle bearing and the pressure bearing are arranged at intervals in the axial direction of the inner shaft, the bearing spacer ring is arranged between the needle bearing and the pressure bearing, the bearing sleeve is arranged outside the needle bearing and the pressure bearing, and the lower end of the bearing sleeve is fixedly connected with the bearing gland through the gland screw. Snap springs are respectively arranged at joints of the upper end of the pressure bearing and the lower end of the bearing gland with the inner shaft; the periphery of the bearing sleeve is tightly matched with the inner wall of the outer shaft through a positioning sleeve. According to the invention, the stability of the single crystal in production can be improved, unrecoverable loss caused by the influence of self gravity and rotation resistance during normal growth of the single crystal is prevented, the complete casting yield of the single crystal is improved, the loss of raw materials is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to a connecting device for stable operation of an axis in a zone melting furnace, belonging to the technical field of producing silicon single crystals by a zone melting method. Background Art

[0002] As we all know, the core of modern information technology and electronic technology is semiconductor technology, and semiconductor silicon single crystal material is the most important semiconductor material. Semiconductor silicon single crystals are mainly produced by Czochralski method and zone melting method. Zone melting silicon single crystal is an excellent material for manufacturing power devices due to its relatively low impurity content.

[0003] In the process of producing silicon single crystals by zone melting, a whole cylindrical polycrystalline material is used. Figure 1 As shown, the existing zone melting furnace inner shaft running connection device has a simple structure, without the inner shaft copper rod stable running support, the inner shaft copper rod 11 is connected at the lower end by the bearing sleeve 20, the self-aligning ball bearing 21 and the retaining spring 22, wherein the self-aligning ball bearing 21 is fixed to the inner side of the bearing sleeve by the retaining spring 22, and the self-aligning ball bearing is connected to the electric cylinder outlet 23. In the early stage of crystal pulling, as the diameter of the single crystal gradually increases, the weight of the single crystal and the weight of the inner shaft are completely borne on the inner shaft running connection device, the self-aligning ball bearing 21 is offset by the longitudinal force, the inner shaft copper rod rotates to produce a certain angle, and there is a large gap between the bearing sleeve 20 and the inner wall of the lower shaft, which generates eccentric rotation and shaking in the process of downward force, and this shaking is fed back to the melting zone through the inner shaft copper rod, which is very likely to cause single crystal breakage and other losses.

[0004] With the advancement of technology, the development of semiconductor silicon materials is very rapid, and silicon single crystals are gradually developing towards large diameters and large weights. With the increase in the diameter of single crystals, the weight of a single silicon single crystal during the production process has exceeded 100 kilograms. In this case, it is difficult to achieve stable growth of single crystals using a simple inner shaft running connection device, and it also has great safety hazards. Therefore, the existing zone furnace inner shaft running connection device cannot meet the requirements of large diameter single crystal processes. Summary of the invention

[0005] The purpose of the present invention is to provide a connecting device for stable operation of the shaft in the zone melting furnace, which is used to improve the stability of the single crystal in production and prevent the single crystal from causing irreversible loss due to its own gravity and rotational resistance during normal growth.

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

[0007] A connecting device for stable operation of the shaft in the zone melting furnace, the connecting device is arranged at the gap between the lower end of the shaft in the zone melting furnace and the inner wall of the outer shaft, and includes a pressure bearing, a needle bearing, a bearing spacer ring, a bearing sleeve, a bearing gland, a retaining spring, and a positioning sleeve;

[0008] The needle roller bearing and the pressure bearing are arranged at intervals along the axial direction of the inner shaft, a bearing spacer ring is arranged between the needle roller bearing and the pressure bearing, the bearing sleeve is arranged outside the needle roller bearing and the pressure bearing, and the lower end of the bearing sleeve is fixedly connected to the bearing gland by a gland screw;

[0009] A retaining spring is provided at the upper end of the pressure bearing and at the connection between the lower end of the bearing gland and the inner shaft;

[0010] The outer periphery of the bearing sleeve is tightly matched with the inner wall of the outer shaft through a positioning sleeve.

[0011] Preferably, the needle bearing is located above the pressure bearing.

[0012] Preferably, a plurality of positioning sleeves are provided and are spaced apart along the axial direction of the inner shaft.

[0013] The advantages of the present invention are:

[0014] The present invention adds a stable connection device at the bottom of the inner shaft copper rod, which greatly improves the stability of the inner shaft operation in the zone melting furnace. Among them, a positioning sleeve is used as a stable support for the downward sliding of the inner shaft. The outer diameter of this wear-resistant positioning sleeve forms an interference fit with the inner wall of the lower shaft, and will not affect the process of the single crystal; a needle bearing is used as a stable support for the rotation of the inner shaft, and the upper part is fixed by the bearing sleeve, and the lower part is fixed by the bearing spacer ring; a pressure bearing is used as a stable support for the downward force of the inner shaft, and the upper part is fixed by the bearing spacer ring, and the lower part is fixed by the bearing pressure cover. Therefore, the present invention adopts a new design concept, a new installation method and a new operating structure method, which can not only improve the complete actual recovery rate of single crystals, but also greatly reduce the loss of raw materials and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The schematic diagram of the structure of the shaft running connection device in the existing zone furnace is shown in FIG.

[0016] Figure 2 It is a schematic structural diagram of the shaft running connection device in the zone melting furnace of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but this does not mean to limit the protection scope of the present invention.

[0018] The present invention adds a stable connection device at the gap between the lower end of the existing inner shaft copper rod 11 (length 2.5 meters) and the inner wall of the outer shaft 12 of the zone melting furnace, transforming the simple bearing and sleeve device into a stable device with independent pressure bearing, rotation and positioning of the inner shaft.

[0019] In the present invention, pressure bearing is the abbreviation of axial pressure bearing, that is, axial radial ball bearing, which is a kind of ball bearing and bears axial force. Needle bearing is equipped with thin and long rollers (roller diameter D≤5mm, L / D is 2.5, L is roller length), so the radial structure is compact, and its outer diameter is the smallest when its inner diameter size and load capacity are the same as other types of bearings. Circlip, also known as retaining ring or snap ring, is a kind of fastener, installed in the circlip groove to prevent the movement of the parts on the inner shaft.

[0020] like Figure 2 As shown, the connection device is composed of a pressure bearing 1, a needle bearing 2, a bearing spacer ring 3, a bearing sleeve 4, a bearing cover 5, a high-precision retaining spring 6, a high-precision retaining spring 7, a cover screw 8, a positioning sleeve 9 and a positioning sleeve 10. Among them, the pressure bearing 1 and the needle bearing 2 are arranged at intervals along the axial direction of the inner shaft, the needle bearing 2 is located above the pressure bearing 1, a bearing spacer ring 3 is arranged between the needle bearing 2 and the pressure bearing 1, the bearing sleeve 4 is arranged outside the needle bearing 2 and the pressure bearing 1, and the lower end of the bearing sleeve 4 is fixedly connected to the bearing cover 5 through the cover screw 8; a high-precision retaining spring 6 is arranged at the connection between the upper end of the pressure bearing 1 and the inner shaft; a high-precision retaining spring 7 is arranged at the connection between the lower end of the bearing cover 5 and the inner shaft; the outer periphery of the bearing sleeve is tightly matched with the inner wall of the outer shaft through the positioning sleeves 9 and 10, that is, interference fit, and the positioning sleeves 9 and 10 are arranged at intervals along the axial direction of the inner shaft.

[0021] In the connecting device of the present invention, a positioning sleeve is used as a stable support for the downward sliding of the inner shaft. The outer diameter of this wear-resistant positioning sleeve forms an interference fit sliding tolerance with the inner wall of the lower shaft, and will not affect the process of the single crystal; a needle roller bearing is used as a stable support for the rotation of the inner shaft, and its upper part is fixed by a bearing sleeve, and its lower part is fixed by a bearing spacer ring; a pressure bearing is used as a stable support for the downward force of the inner shaft, and its upper part is fixed by a bearing spacer ring, and its lower part is fixed by a bearing pressure cover.

[0022] When the connecting device of the present invention is actually installed, the operation process is as follows:

[0023] First, put the needle bearing 2 into the bearing sleeve 4, the inner shaft copper rod 11 goes down into the bearing sleeve 4 and the needle bearing 2, the bearing spacer ring 3 is put into the bearing sleeve 4, the high-precision circlip 6 is inserted into the circlip groove, the pressure bearing 1 and the bearing gland 5 are respectively inserted into the inner shaft from below, and the high-precision circlip 7 is inserted into the circlip groove. The bearing gland 5 and the bearing sleeve 4 are locked by the gland screw 8. The positioning sleeve 9 and the positioning sleeve 10 are tightly matched with the bearing sleeve 4. The overall structure slides along the inner wall of the outer shaft 12 into the inner side of the outer shaft.

[0024] Example

[0025] The single crystal production process includes: preheating → melting → welding → diameter reduction → shoulder release → clamping → equal diameter → finishing.

[0026] When the single crystal grows to a diameter of more than 200 mm, the weight of the single crystal will exceed 10 kg, plus the weight of the inner shaft copper rod (length 2.5 meters) is 20 kg, a total of about 30 kg, and this 30 kg weight is completely borne on the self-aligning ball bearing 11. The self-aligning ball bearing does not have a pressure-bearing function in the longitudinal direction, resulting in large rotation resistance, which causes shaking. This shaking is transmitted to the surface of the molten zone through the inner shaft, causing the surface of the molten zone to fluctuate up and down, and the wire is melted back and broken.

[0027] In the initial stage of shoulder release, since the end of the inner shaft and the end of the electric cylinder cannot be completely through the center, a certain angle will be generated, and this angle will increase as the weight of the single crystal increases. When the bottom angle of the inner shaft reaches a certain amount, a circular trajectory movement with an increasing diameter at the lower end of the copper rod will appear, and the single crystal will also move in a circular motion through the inner shaft. The solution on the surface of the molten zone will splash outwards under the influence of centrifugal force, resulting in a flow molten zone.

[0028] This embodiment adopts the following technical solutions:

[0029] The original inner shaft running connection device is removed, and the connection device designed by the present invention for the stable operation of the inner shaft is installed (this device does not affect other running parts), and it is fixed to the inner shaft by a high-precision retaining spring (such as Figure 2 ).

[0030] In order to prevent the inner shaft from shaking when running downward, positioning sleeves 9 and 10 are specially designed to match the inner wall size of the outer shaft (the positioning sleeves are wear-resistant and do not affect other running parts), and the overall structure is slid into the lower shaft.

[0031] As the gravity of the single crystal gradually increases, the pressure bearing 1 can bear most of the downward force without affecting the rotation of the inner shaft copper rod.

[0032] When the inner shaft rotates, the needle bearing 2 ensures the stability of the rotation and does not participate in the longitudinal pressure.

[0033] It can be seen that the present invention is developed out of the concept that the existing zone furnace inner shaft running connection device cannot provide sufficient stability. By adding the stable running connection device of the present invention in the gap between the inner shaft and the inner wall of the outer shaft, the self-aligning ball bearing 21 no longer bears the downward force given by the inner shaft and the single crystal, and this force is completely borne by the pressure bearing 1. In addition, the self-aligning ball bearing 21 cannot change the angle of the inner shaft copper rod, which is corrected by the positioning sleeve 9 and the positioning sleeve 10, and can only follow the angle of the lower electric cylinder outlet.

Claims

1. A connecting device for stable operation of shafts in a zone furnace, characterized in that: The connecting device is arranged at the gap between the lower end of the inner shaft of the zone melting furnace and the inner wall of the outer shaft, and includes a pressure bearing, a needle bearing, a bearing spacer ring, a bearing sleeve, a bearing gland, a retaining spring, and a positioning sleeve; The needle roller bearing and the pressure bearing are arranged at intervals along the axial direction of the inner shaft, a bearing spacer ring is arranged between the needle roller bearing and the pressure bearing, the bearing sleeve is arranged outside the needle roller bearing and the pressure bearing, and the lower end of the bearing sleeve is fixedly connected to the bearing gland by a gland screw; A retaining spring is provided at the upper end of the pressure bearing and at the connection between the lower end of the bearing gland and the inner shaft; The outer periphery of the bearing sleeve is tightly matched with the inner wall of the outer shaft through a positioning sleeve.

2. The connecting device for stable operation of shaft in zone furnace according to claim 1, characterized in that: The needle roller bearing is located above the pressure bearing.

3. The connecting device for stable operation of shaft in zone furnace according to claim 1 or 2, characterized in that: The positioning sleeves are provided in plurality and are arranged at intervals along the axial direction of the inner shaft.

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