CN118634887A - Electronic grade polysilicon crushing device and crushing method - Google Patents

Abstract

The invention relates to the technical field of polysilicon production and manufacturing, and specifically discloses an electronic-grade polysilicon crushing device and a crushing method, comprising a lifting conveyor line, a silicon material box, a jaw crusher and a high-purity water source; the silicon material box is movably placed on the lifting conveyor line, a jaw crusher is arranged above the lifting conveyor line, a crushing chamber of the jaw crusher is movably placed in the silicon material box, a water inlet and an overflow port are oppositely opened on both sides of the upper end of the silicon material box, the high-purity water source is detachably connected to the water inlet, and the overflow port is connected to a recovery pipeline; through the above structure, the crushing process of the silicon rod occurs in the high-purity water, the high-purity water blocks impurities in the external environment, reduces the probability of impurities invading the gaps of the silicon block, and effectively reduces the impurity content of the silicon block after crushing; using high-purity water replacement during the crushing process can reduce the etching depth in the later pickling process, reduce the quality loss of the silicon block, and improve production efficiency.

Description

Electronic grade polysilicon crushing device and crushing method

Technical Field

The invention relates to the technical field of polysilicon production and manufacturing, and in particular to an electronic-grade polysilicon crushing device and a crushing method.

Background Art

Electronic-grade polysilicon is a key material for manufacturing semiconductor chips. The purity of electronic-grade polysilicon is required to reach 11N, and the impurity content requirements are extremely strict. There are three main sources of impurities on the surface of electronic-grade polysilicon: First, during the reduction and dismantling process, the silicon rods are exposed to the hall environment, and impurities in the air adhere to the surface of the silicon rods; second, during the crushing of the silicon rods, the crushing tools contact the silicon blocks and are contaminated with impurities; third, the crushed silicon blocks have hidden cracks and tiny gaps that are invisible to the naked eye. During transportation and storage, impurities in the air or impurities brought by other tools diffuse into the hidden cracks and gaps and penetrate to a certain depth. Impurities attached to the surface can be removed by mixed acid etching, but impurities that penetrate into the gaps during the crushing process are difficult to remove by cleaning. Therefore, the pollution occurring during the crushing and transportation of silicon blocks is the main reason for the increase in impurity content.

The commonly used crushing methods in the prior art include manual crushing, mechanical crushing, thermal quenching crushing and high-voltage pulse discharge crushing. Among them, manual crushing has low efficiency and high labor intensity, and is gradually replaced by mechanical crushing. The equipment for thermal quenching crushing and high-voltage pulse discharge crushing is expensive, with low production efficiency, and the heating method and heating temperature need to be considered. Additional protective gas is required, resulting in high operating costs. Therefore, the mechanical crushing solution is more suitable in terms of comprehensive cost and crushing effect. Among them, the jaw crusher can meet the needs of large-scale continuous production and can adapt to silicon rods of different sizes. Its crushing efficiency is relatively high. The size of silicon blocks is also relatively uniform; however, during the crushing process of the existing jaw crusher, the jaw plate squeezes the silicon block, causing wear and tear to produce metal impurities that will pollute the silicon block, and the silicon block that is broken into small pieces will produce a large number of cracks after being squeezed by the jaw plate, and impurities are easy to invade and cause deep-level pollution; in order to remove impurities, it is necessary to go through a subsequent silicon block cleaning step, that is, the surface of the silicon block is etched with mixed acid to peel off the epidermis. When the etching thickness is less than the depth of the crack gap, the impurities therein are difficult to be removed; when the etching depth is increased, although impurities can be removed, the loss of silicon material and acid consumption are increased, which reduces production efficiency.

Summary of the invention

The purpose of the present invention is to provide an electronic grade polysilicon crushing device and a crushing method to solve the problem in the prior art that impurities invade the gaps between silicon blocks, resulting in increased silicon material loss, increased acid consumption, and low production efficiency.

The present invention is implemented by the following technical scheme: an electronic-grade polysilicon crushing device, comprising a lifting conveyor line, a silicon material box, a jaw crusher and a high-purity water source; a silicon material box is movably placed on the lifting conveyor line, the top of the silicon material box is open, a jaw crusher is arranged above the lifting conveyor line, the discharge port of the jaw crusher is placed above the scissor-type lifting platform of the lifting conveyor line, the crushing chamber of the jaw crusher is movably placed in the silicon material box, a water inlet and an overflow port are opened on opposite sides of the upper end of the silicon material box, the high-purity water source is detachably connected to the water inlet, and the overflow port is connected to a recovery pipeline.

Furthermore, the jaw crusher includes a frame, an eccentric shaft, an extended movable jaw plate, a static jaw plate, a side guard plate, a toggle plate, a spring pull rod and a driving mechanism. An eccentric shaft is rotatably provided on the frame, and the eccentric shaft is transmission-connected to the driving mechanism. The upper end of the extended movable jaw plate is movably sleeved on the eccentric shaft, a toggle plate is hinged at the middle part of the extended movable jaw plate, and the other end of the toggle plate is fixedly mounted on the frame. A spring pull rod is hinged below the hinged position of the extended movable jaw plate and the toggle plate, and the other end of the spring pull rod is fixedly connected to the frame. The static jaw plate is vertically fixed on the frame, and the static jaw plate extends downward, and its working surface and the lower end working surface of the extended movable jaw plate are located below the horizontal height of the spring pull rod. The working surfaces of the static jaw plate and the lower ends of the extended movable jaw plate and the side guard plates on both sides form a crushing chamber.

Furthermore, the working surfaces and side guard plates of the extended movable jaw plate and the static jaw plate are made of high-purity tungsten carbide.

Furthermore, the lifting conveyor line includes a front conveying platform, a scissor-type lifting platform and a rear conveying platform, and the front conveying platform, the scissor-type lifting platform and the rear conveying platform are connected in sequence.

Furthermore, a weighing sensor is installed below the scissor lift platform.

Furthermore, the high-purity water source is a high-purity water machine, and the impurity control index of the high-purity water machine is: at 25°C, the resistivity reaches 8-10MΩ/cm in 90% of the time.

The present invention further provides a method for crushing polysilicon using the electronic-grade polysilicon crushing device, which specifically comprises the following steps:

S1: The empty silicon material box is transported from the front conveyor to the scissor lift table, and the scissor lift table rises to place the crushing chamber of the jaw crusher in the silicon material box;

S2: Connect the water inlet of the silicon material box to the high-purity water source, connect the overflow port to the recovery pipeline, and add high-purity water to the silicon material box;

S3: After the high-purity water in the silicon material box flows out from the overflow port, the jaw crusher is started, and the silicon rod is put into the jaw crusher from the feed port of the crushing chamber;

S4: When the weighing sensor weighs the silicon blocks in the silicon material box to the set weight and the silicon blocks do not exceed the high-purity water level in the silicon material box, stop crushing, lower the scissor lift table, disconnect the high-purity water source and recovery pipeline from the silicon material box, and the rear conveyor table transfers the silicon material box to the next process. The next empty silicon material box is transported to the scissor lift table by the front conveyor table to start the next crushing operation.

Furthermore, in step S2, the flow rate Q of the high-purity water injection is related to the volume V of the silicon material box and the crushing time t, and the relationship is 2V/t≤Q≤5V/t.

Furthermore, the conductivity of the high-purity water used is 8-10 MΩ/cm.

Advantages of the present invention:

1. The present invention discloses a jaw crusher with an extended movable jaw plate. The crushing chamber of the jaw crusher is placed in a silicon material box, so that the silicon rod is crushed in high-purity water, impurities in the external environment are blocked, the probability of impurities invading the gaps of silicon blocks is reduced, and the impurity content of the silicon blocks after crushing is effectively reduced.

2. The present invention uses high-purity water to continuously replace the impurities in the crushing process, and discharges the impurities generated by machine wear and the impurities brought into the high-purity water by the external environment into the silicon material box in time, which can ensure the cleanliness of the high-purity water in the silicon material box, effectively prevent impurities from invading the cracks of the silicon block, reduce the etching depth in the later pickling process, reduce the quality loss of the silicon block, and improve production efficiency.

3. The present invention replaces traditional manual crushing with mechanical crushing, thereby improving production efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the overall structure of the present invention.

Figure 2 is a schematic diagram of the structure of a jaw crusher.

In the figure: lifting conveyor line 1, silicon material box 2, jaw crusher 3, front conveying platform 101, scissor lifting platform 102, rear conveying platform 103, water inlet 201, overflow port 202, frame 301, eccentric shaft 302, lengthened movable jaw plate 303, static jaw plate 304, side guard plate 305, toggle plate 306, spring pull rod 307, and driving mechanism 308.

DETAILED DESCRIPTION

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the description of the present invention, it should be noted that the terms "center", "up", "down", "front", "back", "top", "bottom", "left", "right", "vertical", "horizontal", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

As shown in Figure 1: an electronic grade polysilicon crushing device includes a lifting conveyor line 1, a silicon material box 2, a jaw crusher 3 and a high-purity water source. The high-purity water source is an existing high-purity water machine. The impurity control index of the high-purity water machine needs to reach: at 25°C, the resistivity reaches 8-10MΩ/cm for 90% of the time, or better than this index; the silicon material box 2 is placed on the lifting conveyor line 1, and the silicon material box 2 is used to load the crushed silicon blocks. The silicon material box 2 is transported up and down the lifting conveyor line 1, and the lifting conveyor Line 1 includes a front conveying platform 101, a scissor lift platform 102 and a rear conveying platform 103, which are connected in sequence, and a weighing sensor is installed under the scissor lift platform 102. The front conveying platform 101 and the rear conveying platform 103 are roller conveyors, and the scissor lift platform 102 is a roller lift platform. The front conveying platform 101, the scissor lift platform 102 and the rear conveying platform 103 are all provided with motor-driven rollers, which can be used to convey the silicon material box 2. The silicon material box 2 has an opening at the top, and a jaw crusher 3 is arranged above the lifting conveyor line 1. The discharge port of the jaw crusher 3 is arranged above the scissor lift 102 of the lifting conveyor line 1. The scissor lift 102 can drive the silicon material box 2 placed on the top surface thereof to move up and down. The silicon material box 2 moves up and down, so that the crushing chamber of the jaw crusher 3 is movably arranged in the silicon material box 2. A water inlet 201 and an overflow port 202 are arranged opposite to each other on both sides of the upper end of the silicon material box 2. The high-purity water source and the water inlet 201 is detachably connected via a quick-release joint, and the overflow port 202 is connected to the recovery pipeline. High-purity water flows into the silicon material box 2 from the water inlet 201, and flows out from the overflow port 202 after the silicon material box 2 is filled, and is recovered and processed via the recovery pipeline. At this time, the crushing chamber of the jaw crusher 3 will be completely immersed in the high-purity water, and during the crushing process, high-purity water is always kept in a state of being filled into the silicon material box 2, so as to carry away impurities generated by the wear of the jaw crusher 3 during the crushing process using the high-purity water flow.

As shown in Figure 2, the jaw crusher 3 includes a frame 301, an eccentric shaft 302, an extended movable jaw plate 303, a static jaw plate 304, a side guard plate 305, a toggle plate 306, a spring pull rod 307, a driving mechanism 308 and a side guard plate 305. An eccentric shaft 302 is rotatably provided on the frame 301, and the eccentric shaft 302 is transmission-connected with the driving mechanism 308. The upper end of the extended movable jaw plate 303 is movably sleeved on the eccentric shaft 302, and a toggle plate 306 is hingedly connected to the middle part of the extended movable jaw plate 303, and the other end of the toggle plate 306 is fixedly mounted on the frame 301. It should be noted that the toggle plate 306 has a certain elasticity. The characteristics of the toggle plate 306 are the same as those of a leaf spring. It is made of elastic metal, and one end of the toggle plate 306 hinged to the extended movable jaw plate 303 can produce a certain amplitude of up and down movement under the driving action of the extended movable jaw plate 303. The movable jaw plate 303 is hinged to the frame 301 and the static jaw plate 304 is vertically fixed to the frame 301. The structure and working principle of the movable jaw plate 303 are similar to those of the existing jaw crusher. The eccentric shaft 302 is driven to rotate by the driving mechanism 308, and the upper end of the movable jaw plate 303 is driven to perform eccentric rotation. The middle part of the movable jaw plate 303 is hinged to the frame 301 through the toggle plate 306 and the spring pull rod 307, so that the movable jaw plate 303 is swung as a whole with the toggle plate 306 as the fulcrum. When swinging, the distance between the movable jaw plate 303 and the bottom working surface of the static jaw plate 304 changes periodically, which produces the movement of the two jaws of an animal to squeeze the silicon rod and complete the crushing.

The difference of the jaw crusher 3 described in the present invention is that the static jaw plate 304 extends downward, and its working surface and the working surface of the lower end of the extended movable jaw plate 303 are located below the horizontal height of the spring pull rod 307. The lower end working surfaces of the static jaw plate 304 and the extended movable jaw plate 303 and the side guard plates 305 on both sides form a crushing chamber; through the above structure, the crushing chamber can be placed in a silicon material box 2 filled with high-purity water, so that the silicon rod is in a high-purity water environment when it is crushed, and the crushing process of the silicon rod is isolated from the external environment. High-purity water is used instead of air to reduce the probability of impurities in the environment invading the cracks of the silicon block, thereby achieving the effect of reducing the impurity content in the silicon block; the working surfaces of the extended movable jaw plate 303 and the static jaw plate 304 and the side guard plates 305 are made of high-purity tungsten carbide, which can reduce the metal impurities remaining on the surface of the silicon block and reduce the pollution caused by grinding of the working surface.

The crushing step of the electronic grade polysilicon crushing device comprises the following steps:

S1: The empty silicon material box 2 is transported from the front conveying platform 101 to the scissor lift platform 102, and the scissor lift platform 102 rises to place the crushing chamber of the jaw crusher 3 in the silicon material box 2;

S2: Connect the water inlet 201 of the silicon material box 2 to a high-purity water source, connect the overflow port 202 to a recovery pipeline, and add high-purity water into the silicon material box 2;

S3: After the high-purity water in the silicon material box 2 flows out from the overflow port 202, the jaw crusher 3 is started, and the silicon rods are put into the crushing chamber of the jaw crusher 3 from the feed port;

S4: When the weighing sensor weighs the silicon blocks in the silicon material box 2 to the set weight and the silicon blocks do not exceed the high-purity water level in the silicon material box 2, the crushing is stopped, the scissor lift table 102 is lowered, and the connection pipelines between the high-purity water source and the recovery pipeline and the silicon material box 2 are disconnected. The rear conveyor table 103 transfers the silicon material box 2 to the next process, and the next empty silicon material box 2 is transported by the front conveyor table 101 to the scissor lift table 102 to start the next crushing operation.

In step S2, the flow rate Q of high-purity water injection is related to the volume V of the silicon material box 2 and the crushing time t, and the relationship is 2V/t≤Q≤5V/t, that is, during the crushing cycle, the total amount of high-purity water injected into the silicon material box 2 is 2-5 times the volume of the material box.

The conductivity of the high-purity water used above is 8-10 MΩ/cm.

To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

Embodiment 1: The device and method described in the present invention are used to crush silicon rods. The total water volume of the silicon material box 2 used is 50L, the single crushing time is 100s, the flow rate of high-purity water injection during the crushing process is 1L/s, and the size of the silicon block is controlled within 25-50mm; the crushed silicon block is transferred to the pickling process for cleaning, and sequentially undergoes: a. high-purity water washing (conductivity after cleaning is 8-10MΩ/cm); b. alkali washing (sodium hydroxide); c. high-purity water washing (conductivity after cleaning is 8-10MΩ/cm); d. mixed acid etching (nitric acid plus hydrofluoric acid 1wt% hydrofluoric acid, mass concentration of 70wt% nitric acid); e. high-purity water washing (conductivity after cleaning is 8-10MΩ/cm); the processing cycle of the above steps is 180s, and the etching depth of the silicon block surface is controlled to be 5μm.

Embodiment 2: The overall method is the same as that of Embodiment 1, except that the cycle time of each step of cleaning the silicon block is 300 seconds, and the etching depth of the silicon block surface is controlled to be 15 μm.

Comparative Example 1: The same silicon rod product produced at the same time in the same reduction furnace as in Example 1 was used, and the production conditions before crushing were the same, that is, the impurities on the original body surface were basically the same; the silicon rod was knocked and crushed using a tungsten carbide hammer in an ISO7 dust-free operation room, and the size of the silicon block was controlled within 25-50 mm. The crushed silicon block was transferred to the pickling process for cleaning, and sequentially went through: a. high-purity water washing (conductivity after cleaning 8-10 MΩ/cm); b. alkali washing (sodium hydroxide); c. high-purity water washing (conductivity after cleaning 8-10 MΩ/cm); d. mixed acid etching (nitric acid plus hydrofluoric acid 1wt% hydrofluoric acid, mass concentration of 70wt% nitric acid); e. high-purity water washing (conductivity after cleaning 8-10 MΩ/cm); the processing cycle of each of the above steps was 180s, and the etching depth of the silicon block surface was controlled to be 5μm.

Comparative Example 2: The overall method is the same as that of Comparative Example 1, except that the cycle time of each step of cleaning the silicon block is 300 seconds, and the etching depth of the silicon block surface is controlled to be 15 μm.

Three silicon block samples obtained in Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were taken respectively to measure the carbon content and the donor and acceptor impurity content.

Detection method:

Carbon content: The samples were tested using the method of GBT 35306-2017 “Determination of carbon and oxygen content in silicon single crystals - Low temperature Fourier transform infrared spectroscopy”.

Donor and acceptor impurity content: The samples were tested using the determination method of GBT 24581-2022 "Determination of Group III and Group V impurity content in silicon single crystals, low-temperature Fourier transform infrared spectroscopy".

Through the above detection method, the carbon content, donor impurity content and acceptor impurity content in 12 samples were measured as shown in Table 1:

Table 1

It can be seen from the above table that for the silicon blocks broken by the device and method described in Example 1 of the present invention, when the cleaning and etching thickness is 15 μm, the difference in impurity content in the silicon blocks by the manual breaking method and the method of the present invention is not much; when the cleaning and etching thickness is 5 μm, the impurity content of the manually broken silicon blocks after cleaning is still high, while the impurity content of the silicon blocks broken by the device and method of the present invention can reach the predetermined standard after cleaning; therefore, the present method can greatly reduce the etching thickness, reduce the loss of silicon block quality, save costs, and improve production efficiency.

Claims (9)

1. An electronic grade polycrystalline silicon crushing device is characterized by comprising a lifting conveying line (1), a silicon material box (2), a jaw crusher (3) and a high-purity water source; the utility model provides a silicon workbin (2) is placed in the removal on lift transfer chain (1), silicon workbin (2) open-top, be equipped with jaw breaker (3) above lift transfer chain (1), the top of scissor lift platform (102) of lift transfer chain (1) is arranged in to the discharge gate of jaw breaker (3), in silicon workbin (2) is arranged in the broken chamber activity of jaw breaker (3), water inlet (201) and overflow mouth (202) have been offered in opposite directions in silicon workbin (2) upper end both sides, high-purity water source and water inlet (201) can dismantle and be connected, overflow mouth (202) are connected with recovery pipeline.

2. An electronic grade polysilicon crushing apparatus according to claim 1, wherein the jaw crusher (3) comprises a frame (301), an eccentric shaft (302), an elongated movable jaw (303), a stationary jaw (304), a side guard (305), a toggle plate (306), a spring pull rod (307) and a driving mechanism (308), wherein the eccentric shaft (302) is rotatably arranged on the frame (301), the eccentric shaft (302) is in transmission connection with the driving mechanism (308), the upper end of the elongated movable jaw (303) is movably sleeved on the eccentric shaft (302), the middle part of the elongated movable jaw (303) is hinged with the toggle plate (306), the other end of the toggle plate (306) is fixedly arranged on the frame (301), the spring pull rod (307) is hinged below the hinged position of the elongated movable jaw (303) and the toggle plate (306), the other end of the spring pull rod (307) is fixedly connected with the frame (301), the stationary jaw (304) is vertically fixed on the frame (301), the stationary jaw (304) extends downwards, the working face of the stationary jaw (304) and the lower end of the elongated movable jaw (303) is positioned at the lower end of the stationary jaw (303) and the lower end of the spring pull rod (307) is positioned at the two sides of the stationary jaw (305), and the lower end of the stationary jaw (303) is positioned at the lower end of the stationary jaw (305).

3. An electronic grade polysilicon crushing apparatus according to claim 2, wherein the working surfaces of the elongated swing jaw (303), the stationary jaw (304) and the edge guard (305) are made of high purity tungsten carbide.

4. An electronic grade polysilicon crushing apparatus according to claim 1, wherein the elevation transport line (1) comprises a front transport table (101), a scissor lift table (102) and a rear transport table (103), and the front transport table (101), the scissor lift table (102) and the rear transport table (103) are connected in sequence.

5. An electronic grade polysilicon crushing apparatus according to claim 4, characterized in that a load cell is mounted below the scissor lift (102).

6. The electronic grade polysilicon crushing device of claim 1, wherein the high purity water source is a high purity water machine, and the impurity control index of the high purity water machine is: at 25 ℃, the resistivity is reached within 90% of the time: 8-10M omega/cm.

7. A method for breaking electronic grade polycrystalline silicon using an electronic grade polycrystalline silicon breaking device according to claim 1, comprising the steps of:

S1: the empty silicon material box (2) is conveyed to a scissor type lifting platform (102) by a front conveying platform (101), and the scissor type lifting platform (102) is lifted, so that a crushing cavity of the jaw crusher (3) is arranged in the silicon material box (2);

s2: a water inlet (201) of the silicon material box (2) is connected with a high-purity water source, an overflow port (202) is connected with a recovery pipeline, and high-purity water is filled into the silicon material box (2);

S3: starting the jaw crusher (3) after high-purity water in the silicon material box (2) flows out from the overflow port (202), and throwing silicon rods into the jaw crusher (3) from a feeding port of a crushing cavity;

S4: the weighing sensor is used for weighing the silicon blocks in the silicon material box (2) to a set weight, the silicon blocks do not exceed the liquid level of high-purity water in the silicon material box (2), crushing is stopped, the shear type lifting table (102) is lowered, the high-purity water source and the connecting pipeline of the recovery pipeline and the silicon material box (2) are disconnected, the silicon material box (2) is transferred to the next procedure by the rear conveying table (103), the next empty silicon material box (2) is conveyed to the shear type lifting table (102) by the front conveying table (101), and the next crushing operation is started.

8. The method for breaking electronic grade polycrystalline silicon by an electronic grade polycrystalline silicon breaking device according to claim 7, wherein in step S2, the flow rate Q of high purity water injection is related to the volume V of the silicon tank (2) and the breaking time t, with the relationship of 2V/t.ltoreq.q.ltoreq.5v/t.

9. The method for breaking electronic grade polycrystalline silicon as set forth in claim 7, wherein the high purity water used has a conductivity of 8-10mΩ/cm.