Single crystal furnace cleaning method

Abstract

The application provides a single crystal furnace cleaning method and relates to the technical field of single crystal furnace cleaning. When a furnace table is running, oxide adhesion is prevented by argon blowing, so that in the environment of crystal bar growth, the oxide is not only prevented from adhering to the inner wall of the single crystal furnace, but also prevented from causing pollution to the crystal bar. When the furnace table stops running, the furnace table is cleaned comprehensively, so that the furnace table is clean, the crystal growth environment is guaranteed, and the product quality is ensured.

Description

Technical Field

[0001] This invention belongs to the technical field of single crystal furnace cleaning, and specifically relates to a single crystal furnace cleaning method. Background Technology

[0002] Semiconductor single crystal growth furnaces are essential equipment in the process of converting polycrystalline silicon into single crystal silicon. A clean, dust-free environment is required for ingot growth within the furnace. However, oxide dust is generated during the growth process and adheres to the walls of the main and auxiliary furnace chambers. After ingot growth is complete, the oxide dust adhering to the chamber walls must be cleaned to prevent it from affecting the environment for subsequent crystal growth. If not cleaned, the oxide dust will fall onto the liquid surface and enter the crystal during growth, altering the lattice arrangement and causing ingot breakage. This leads to unnecessary ingot product loss, such as breakage and material spillage, and reduced product yield. Remelting and growing the crystal again increases the electricity and material costs associated with the crystal growth process. Furthermore, dust entering the crystal can cause minute crystal defects, resulting in product scrap. Summary of the Invention

[0003] In view of this, the present invention provides a method for thoroughly cleaning a single crystal furnace.

[0004] The technical solution adopted by this invention to solve its technical problem is:

[0005] A method for cleaning a single crystal furnace involves purging with argon gas during furnace operation to prevent oxide adhesion, and performing a thorough cleaning of the furnace platform when it is not in operation, thus keeping the furnace platform clean.

[0006] Preferably, the specific steps for thoroughly cleaning the furnace platform when it is not in operation are as follows:

[0007] S1: Unscrew the auxiliary furnace chamber, remove the crystal rod, and clean the auxiliary furnace chamber;

[0008] S2: Unscrew the furnace cover and clean the inner wall of the furnace cover and the valve chamber.

[0009] S3: Remove the heater and clean the lower furnace cylinder and furnace bottom;

[0010] S4: Clean the graphite components, heating components, crucible, and heat shield in sequence;

[0011] S5: Finally, clean the upper furnace drum.

[0012] Preferably, in steps S1 to S4, lint-free paper is used for wiping and then the dust is absorbed.

[0013] Preferably, before wiping with lint-free paper, spray alcohol onto the lint-free paper and then wipe.

[0014] Preferably, in step S5, a cleaning turntable is used for cleaning. The cleaning turntable is disc-shaped, and a cleaning brush is provided on the circumferential side wall of the cleaning turntable. The cleaning turntable rotates clockwise, and the cleaning brush contacts the inner wall of the upper furnace cylinder.

[0015] Preferably, the cleaning turntable is hollow inside, and a cleaning hole is provided in the middle of the side of the cleaning turntable along the circumferential direction. The cleaning hole is connected to the interior of the cleaning turntable. The cleaning brush is composed of an array of cleaning parts, and each cleaning part is composed of several cleaning components. The cleaning components are arranged on both sides of the cleaning hole. Each set of cleaning parts moves from the edge of the cleaning turntable toward the cleaning hole in a clockwise direction. Adjacent cleaning parts overlap each other, so that the entire cleaning brush is spirally distributed.

[0016] Preferably, the cleaning turntable is rotatably connected to the adsorption tube, and the adsorption tube is connected to the hollow inner cavity of the cleaning turntable. The cleaning turntable rotates to clean the inner wall of the upper furnace cylinder, and the cleaning brush contacts the inner wall of the upper furnace cylinder for brushing. The adsorption tube uses negative pressure adsorption, so that the oxides brushed out are adsorbed into the interior of the cleaning turntable by the cleaning holes.

[0017] Preferably, the cleaning hole is funnel-shaped.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention provides a method for cleaning a single crystal furnace. During furnace operation, argon gas is used to purge and prevent oxides from adhering. This avoids oxides adhering to the inner wall of the single crystal furnace and preventing oxides from contaminating the crystal rods in the crystal growth environment. When the furnace stops operating, a thorough cleaning is performed on the furnace to ensure a clean furnace, protect the crystal growth environment, and ensure product quality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the cleaning turntable.

[0021] Figure 2 A front view of the cleaning turntable.

[0022] Figure 3 This is a front view of a single crystal furnace.

[0023] Figure 4 This is a cross-sectional view of the isolation valve.

[0024] Figure 5 This is a schematic diagram of the second flange.

[0025] In the figure: upper furnace cylinder 100, cleaning turntable 110, cleaning hole 111, cleaning brush 120, cleaning section 121, cleaning component 122, adsorption tube 130, isolation valve 200, connecting purging section 210, first flange 211, second flange 212, purging hole 2121, annular cavity 2122, vent pipe 213, opening and closing section 220, cylinder drive component 221, flexible shaft 222, isolation valve body 223, housing 224, accommodating cavity 2241, vacuum discharge pipe 300. Detailed Implementation

[0026] The technical solutions and effects of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0027] A method for cleaning a single crystal furnace involves purging with argon gas during furnace operation to prevent oxide adhesion, and performing a thorough cleaning of the furnace platform when it is not in operation, thus keeping the furnace platform clean.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The present invention provides a method for cleaning a single crystal furnace. During furnace operation, argon gas is used to purge and prevent oxides from adhering. This avoids oxides adhering to the inner wall of the single crystal furnace and preventing oxides from contaminating the crystal rods in the crystal growth environment. When the furnace stops operating, a thorough cleaning is performed on the furnace to ensure a clean furnace, protect the crystal growth environment, and ensure product quality.

[0030] Furthermore, the specific steps for thoroughly cleaning the furnace platform when it is not in operation are as follows:

[0031] S1: Unscrew the auxiliary furnace chamber, remove the crystal rod, and clean the auxiliary furnace chamber;

[0032] S2: Unscrew the furnace cover and clean the inner wall of the furnace cover and the valve chamber.

[0033] S3: Remove the heater and clean the lower furnace cylinder and furnace bottom;

[0034] S4: Clean the graphite components, heating components, crucible, and heat shield in sequence;

[0035] S5: Final cleaning of the upper furnace drum 100.

[0036] Furthermore, in steps S1 to S4, lint-free paper is used for wiping and then the dust is absorbed.

[0037] Furthermore, before wiping with lint-free paper, spray alcohol onto the lint-free paper and then wipe to make the cleaning more thorough.

[0038] Please refer to Figure 1 and Figure 3Furthermore, in step S5, a cleaning turntable 110 is used for cleaning. The cleaning turntable 110 is disc-shaped, and a cleaning brush 120 is provided on the circumferential side wall of the cleaning turntable 110. The cleaning turntable 110 rotates clockwise, and the cleaning brush 120 contacts the inner wall of the upper furnace cylinder 100.

[0039] Furthermore, the cleaning turntable 110 is hollow inside, and a cleaning hole 111 is provided in the middle of the side of the cleaning turntable 110 along the circumferential direction. The cleaning hole 111 is connected to the interior of the cleaning turntable 110. The cleaning brush 120 is composed of an array of cleaning parts 121. Each cleaning part 121 is composed of several cleaning components 122. The cleaning components 122 are arranged on both sides of the cleaning hole 111. Each set of cleaning parts 121 moves from the edge of the cleaning turntable 110 toward the cleaning hole 111 in a clockwise direction. Adjacent cleaning parts 121 overlap each other, so that the entire cleaning brush 120 is spirally distributed.

[0040] Furthermore, the cleaning turntable 110 is rotatably connected to the adsorption tube 130, and the adsorption tube 130 is connected to the hollow inner cavity of the cleaning turntable 110. The cleaning turntable 110 rotates to clean the inner wall of the upper furnace cylinder 100. The cleaning brush 120 contacts the inner wall of the upper furnace cylinder 100 to brush and wash, so that the oxides attached to the inner wall of the upper furnace cylinder 100 are turned into fine particles. The adsorption tube 130 adsorbs under negative pressure, so that the oxides brushed out are adsorbed into the interior of the cleaning turntable 110 by the cleaning hole 111. This allows the oxide particles and dust brushed by the cleaning brush 120 to be directly cleaned out, reducing the deposition of oxide dust and making the upper furnace cylinder 100 clean and thorough.

[0041] Furthermore, the cleaning hole 111 is funnel-shaped.

[0042] Specifically, the cleaning turntable 110 can be moved up and down using a telescopic rod. One end of the telescopic rod is rotatably connected to the cleaning turntable 110, and the other end is held by hand, so that the cleaning turntable 110 can move up and down.

[0043] Specifically, the cleaning turntable 110 can be driven to rotate by a motor. When the motor drives the cleaning turntable 110 to rotate instantaneously, the rotation of the cleaning turntable 110 drives the cleaning brush 120 to rotate, thus cleaning the upper furnace cylinder 100. Simultaneously, the oxides separated from the upper furnace cylinder 100 are kept agglomerated near the cleaning holes 111 by the spiral arrangement of the cleaning components and the suction of the cleaning holes 111. This prevents oxide particles and dust from falling into the cleaned area of ​​the upper furnace cylinder 100, thus avoiding re-contamination. Furthermore, during the adsorption process, the cleaning holes 111 are funnel-shaped, with a small opening near the hollow cavity of the cleaning turntable 110 and a small opening near the outer edge of the cleaning turntable 110. The large opening of the cleaning hole 111 allows it to collect oxide particles and dust during the adsorption process of the adsorption tube 130. As the diameter of the cleaning hole 111 decreases, the oxide particles and dust adsorbed into the cleaning hole 111 rotate in a spiral shape and enter the hollow cavity inside the cleaning disc 110. This causes large oxide particles to collide with the inner wall of the cleaning hole 111 and other particulate oxides during rotation, making the particles gradually smaller and easier to enter the hollow cavity inside the cleaning disc 110 through the small opening of the cleaning hole 111. This also prevents the small opening of the cleaning hole 111 from becoming clogged.

[0044] Please check Figures 4 to 5 To prevent oxide adhesion during furnace operation, argon gas purging is used. Specifically, the isolation valve 200 includes a connecting purging part 210 and an opening / closing part 220. The connecting purging part 210 includes a first flange 211, a second flange 212, and a vent pipe 213. An annular cavity 2122 is formed inside the second flange 212, and several purging holes 2121 are evenly arranged on the inner side of the second flange 212. The several purging holes 2121 are inclined in one direction and communicate with the annular cavity 2122. The first flange 211 and the second flange 212 are symmetrically arranged above and below the opening / closing part 220. The upper furnace cylinder 100 is connected to the upper end face of the first flange 211, the first flange 211 is connected to the upper end of the opening and closing part 220, the lower end of the opening and closing part 220 is connected to the second flange 212, and the vent pipe 213 is connected to the second flange 212 to communicate with the annular cavity 2122. By blowing argon into the vent pipe 213 and the interior of the annular cavity 2122, the argon is blown out from the purge hole 2121 with the same inclined direction. The argon forms a vortex gas film on the inner annular wall of the second flange 212, preventing the generation of stray flow and preventing oxides from accumulating in the opening and closing part 220.

[0045] Specifically, since the purging holes 2121 of the isolation valve 200 are tilted in the same direction, argon gas is introduced into the vent pipe 213 before the secondary feeding begins. The argon gas enters the annular cavity 2122 and is purged through the purging holes 2121. On the one hand, this stabilizes the gas field in the single crystal furnace, prevents the formation of stray flow after the opening and closing part 220 is opened, and reduces the generation of oxides. On the other hand, the introduced argon gas forms a vortex gas film on the inner annular wall of the second flange 212, which purges the oxides and prevents the oxides from accumulating and condensing in the opening and closing part 220, keeping the inner wall of the opening and closing part 220 clean. After the secondary feeding is completed, the oxides are discharged, reducing the probability of oxides falling into the quartz crucible, thereby reducing the yield of the crystal rod and reducing the number of NGs. Furthermore, the isolation valve 200 no longer needs to be cleaned frequently, reducing the workload and improving the equipment uptime.

[0046] Furthermore, the arc length spacing between the purge holes 2121 is 4cm-8cm.

[0047] Furthermore, the diameter of the purge hole 2121 is 5mm-10mm.

[0048] Furthermore, all the purge holes 2121 are located on the same plane, and the inclination angle A of the purge holes 2121 on the horizontal plane is 10°-30°.

[0049] Furthermore, the purge hole 2121 has an inclination angle A of 15° on the horizontal plane, and the inclination direction of several purge holes 2121 is consistent. During the argon purging process, the argon gas blown out of one purge hole 2121 is blown to the next purge hole 2121, so that the argon gas introduced forms a vortex gas film on the inner ring wall of the second flange 212, preventing oxides from accumulating and agglomerating around the isolation valve body 223.

[0050] Furthermore, the opening / closing part 220 includes a cylinder drive 221, a flexible shaft 222, an isolation valve body 223, and a housing 224. The cylinder drive 221 and the flexible shaft 222 are located outside the housing 224. The housing 224 is connected to the outer circumferential surfaces of the first flange 211 and the second flange 212. One side of the housing 224 is connected to the first flange 211 and the second flange 212 to form a receiving cavity 2241. The cylinder drive 221 is connected to one end of the flexible shaft 222, and the other end of the flexible shaft 222 is connected to the isolation valve body 223 via a coupling. When the isolation valve body 223 is closed... At 23:00, the solenoid valve opens, and the isolation valve body 223 moves upward appropriately to reduce wear. The cylinder drive 221 drives the isolation valve body 223 to rotate between the first flange 211 and the second flange 212, closing the solenoid valve. The lower end face of the isolation valve body 223 fits against the second flange 212, thus closing the isolation valve body 223. When the isolation valve body 223 is opened, the solenoid valve opens, and the isolation valve body 223 moves upward appropriately. The cylinder drive 221 drives the isolation valve body 223 to rotate into the receiving cavity 2241, thus opening the isolation valve body 223 and connecting the upper furnace cylinder 100 with the middle furnace cylinder.

[0051] Specifically, the first flange 211, the second flange 212, and the isolation valve body 223 are coaxial, and the distance between the first flange 211 and the second flange 212 is greater than the height of the isolation valve body 223.

[0052] During the Czochralski (CZ) single crystal growth process, 70-90 slm of argon gas is continuously introduced into the single crystal furnace. The gas flow is from top to bottom. During the secondary feeding process, the isolation valve body 223 is opened, disrupting the gas flow within the furnace. Stray flow carries oxides and accumulates at the isolation valve. Therefore, before the secondary feeding, 60 slm of argon gas is introduced into the vent pipe 213. The argon gas enters the annular cavity 2122 and is purged through the purge holes 2121 with an arc length spacing of 5 cm and a diameter of 8 mm. This stabilizes the gas field within the single crystal furnace and prevents the isolation valve body 223 from rotating into the receiving cavity 2241, thus reducing oxide formation. The purge holes 2121 are tilted in the same direction, ensuring that during the argon purging process, the argon gas blown from one purge hole 2121 reaches the next purge hole. At position 2121, the introduced argon gas forms a vortex gas film on the inner ring wall of the second flange 212, preventing oxides from accumulating and agglomerating around the isolation valve 200. After the secondary feeding is completed, the isolation valve body 223 is closed, and 70slm-90slm of argon gas continues to be introduced into the Czochralski single crystal furnace, while 60slm of argon gas continues to be introduced into the vent pipe 213, maintaining a pressure of 2kPa. The flow rate of argon gas introduced into the vent pipe 213 is less than the flow rate of argon gas introduced into the single crystal furnace, causing the oxides in the vortex in the gas to gradually swirl and move downward under the guidance of the vortex gas until they are discharged into the vacuum exhaust pipe 300400, reducing the oxides in the single crystal furnace, thereby reducing the risk of oxides falling into the quartz crucible and contaminating the silicon solution, thus reducing the probability of NG (non-productive) and reducing the number of times the staff cleans the isolation valve body 223.

[0053] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method of cleaning a single crystal furnace, the method comprising: Prevent the attachment of oxides by argon purging during the operation of the furnace platform, protect the cleanliness of the internal isolation valve, ​ The isolation valve of the single crystal furnace comprises a connecting purging part and an opening and closing part, the connecting purging part comprises a second flange, an annular cavity is formed in the second flange, a plurality of purging holes are uniformly arranged on the inner side of the second flange, the lower end of the opening and closing part is connected with the second flange, and a layer of vortex gas film is formed on the inner annular wall of the second flange and rotates; Comprehensively clean the furnace platform when the furnace platform stops running, so that the furnace platform is clean; The specific steps of comprehensively cleaning the furnace platform when the furnace platform stops running are as follows: S1: unscrew the auxiliary furnace chamber, take out the crystal bar, and clean the auxiliary furnace chamber; S2: unscrew the furnace cover, and clean the inner wall of the furnace cover and the valve chamber; S3: take out the heater to clean the lower furnace cylinder and the furnace bottom; S4: sequentially clean the graphite components, heating components, crucible, and heat shield; S5: finally clean the upper furnace cylinder; In the S5 step, a cleaning turntable is used for cleaning, the cleaning turntable is in the shape of a round cake, cleaning brushes are arranged on the circumferential side wall of the cleaning turntable, the cleaning turntable rotates clockwise, and the cleaning brushes contact the inner wall of the upper furnace cylinder; The cleaning turntable is hollow, cleaning holes are arranged on the circumferential side of the middle part of the cleaning turntable, the cleaning holes are in communication with the interior of the cleaning turntable, the cleaning brushes are composed of a plurality of cleaning parts, each cleaning part is composed of a plurality of cleaning components, the cleaning components are arranged on both sides of the cleaning hole, each group of cleaning parts approaches the cleaning hole from the edge of the cleaning turntable in the clockwise direction, and adjacent cleaning parts are superimposed on each other, so that the entire cleaning brush is spirally distributed; The cleaning turntable is rotationally connected with a suction pipe, the suction pipe is in communication with the hollow inner cavity of the cleaning turntable, the cleaning turntable rotates to clean the inner wall of the upper furnace cylinder, the cleaning brushes contact the inner wall of the upper furnace cylinder to perform brushing, and the suction pipe is negatively adsorbed, so that the brushed oxides are adsorbed into the interior of the cleaning turntable through the cleaning holes.

2. The single crystal furnace cleaning method of claim 1, wherein: In the S1 to S4 steps, dust-free paper is used for wiping, and then the dust is adsorbed.

3. The single crystal furnace cleaning method of claim 2, wherein: Before wiping with the dust-free paper again, alcohol is sprayed on the dust-free paper, and then the dust-free paper is wiped again.

4. The method of claim 1, wherein: The cleaning hole is in the shape of a horn.

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