Efficient cleaning method and device for polycrystalline silicon back-sealed LPCVD furnace tube

Abstract

The invention relates to the technical field of semiconductor monocrystalline silicon wafer substrate manufacturing, in particular to an efficient cleaning method and device for a polycrystalline silicon back-sealed low pressure chemical vapor deposition (LPCVD) furnace tube. Comprising the following steps: respectively putting an inner tube Tube-1 and an outer tube Tube-2 of the LPCVD into two cleaning tanks of a furnace tube cleaning machine, and washing with high-purity deionized water; respectively soaking the flushed furnace tubes in a mixed acid solution with a certain concentration; spraying and cleaning the furnace tube soaked in the mixed acid by using high-purity deionized water; soaking the furnace tube soaked in the mixed acid by using a DHF solution with a certain concentration; spraying and cleaning the furnace tube soaked in the DHF solution by using high-purity deionized water; blowing and drying the furnace tube flushed by the pure water by using N2; and carrying out surface detection on the dried furnace tube. The method is easy and convenient to design and operate, remarkable in effect and high in flexibility, impurities such as a polycrystalline silicon layer and particles generated on the surface of the LPCVD furnace tube in the reaction process can be effectively removed under the condition that the surface of the furnace tube is not damaged, and the service life of the furnace tube can be obviously prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor single crystal silicon wafer substrate manufacturing, and in particular to a high-efficiency cleaning method and device for LPCVD furnace tubes used for polysilicon back sealing. Background Art

[0002] To obtain high-performance semiconductor power devices, silicon wafers need to be epitaxially grown. Doping control is an important step in the vapor phase epitaxy process. Different electronic device performances can be achieved by doping with different P-type or N-type dopants. When doping, if impurities in the silicon wafer itself are precipitated and impurities are doped, it may affect the electrical properties of the silicon wafer. Therefore, during the processing of the substrate silicon wafer, the back side needs to be treated with impurity gettering.

[0003] The commonly used gettering method is the polysilicon back seal on the back of the silicon wafer. The process is to use SiH 4 Thermal decomposition generates polysilicon, which is then deposited on the surface of the silicon wafer to form a layer of polysilicon. The low-pressure chemical vapor deposition process is usually achieved through LPCVD equipment. During the reaction, the silicon carbide paddle carries the silicon wafer into the silicon carbide tube. The outside is connected with quartz tubes, metal furnace doors, pipes and vacuum pumps to form a low-pressure environment. Polysilicon is deposited on the surface of the silicon wafer and directly on the inner wall of the furnace tube. When the polysilicon layer on the inner wall of the furnace tube reaches a certain thickness, the deposition of the polysilicon layer on the surface of the silicon wafer will cause abnormal parameters and poor surface particles on the silicon wafer. Therefore, when the polysilicon layer on the tube wall reaches the specified thickness (about 40-50um), the furnace tube needs to be maintained.

[0004] The commonly used maintenance method is to remove the LPCVD furnace tube and clean it. During the cleaning process, it is necessary not only to ensure that the residues on the tube wall are completely removed, but also to ensure that the tube wall is not damaged, which will affect the service life. Since the cleaning frequency of the furnace tube is high (2 to 3 times / month), it is very important to develop an efficient and low-damage furnace tube maintenance method. In view of the problem that the existing cleaning process has a slow cleaning rate and poor effect on the polysilicon layer of the LPCVD furnace tube, which easily leads to excessive particles, we proposed an efficient cleaning method and device for the LPCVD furnace tube with polysilicon back seal. Summary of the invention

[0005] The object of the present invention is to provide a highly efficient cleaning method and device for LPCVD furnace tubes used for polysilicon back sealing, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above-mentioned technical problems, one of the objects of the present invention is to provide a high-efficiency cleaning device for LPCVD furnace tubes for polysilicon back sealing, including a furnace tube cleaning machine, wherein the furnace tube cleaning machine is provided with two cleaning tanks of the same structure, wherein the inner wall brush shaft and the side wall brush shaft are connected and rotated side by side in the cleaning tank, the outer side of the inner wall brush shaft is provided with an inner wall brush, and the outer side of the side wall brush shaft is provided with an outer wall brush, and at least two furnace tube rotating rollers are distributed in a circular arc at the lower end of the cleaning tank below the inner wall brush shaft.

[0007] As a further improvement of the technical solution, the cleaning tank is made of polytetrafluoroethylene, and a lateral entry and exit structure for accommodating the entry and exit of the LPCVD furnace tube is provided at one end of the cleaning tank corresponding to the inner wall brush shaft.

[0008] As a further improvement of the technical solution, the arc surface where several of the furnace tube rotating rollers are located is arranged cocentrically with the center line of the inner wall brush rotating shaft, the outer diameter of the inner wall brush is adapted to the inner diameter of the LPCVD furnace tube, and the minimum distance between the inner wall brush and the outer wall brush is adapted to the tube wall thickness of the LPCVD furnace tube; when the LPCVD furnace tube is sleeved on the outside of the inner wall brush rotating shaft and placed on several of the furnace tube rotating rollers, the inner wall brush and the outer wall brush are in contact with the inner and outer walls of the LPCVD furnace tube respectively.

[0009] The second object of the present invention is to provide a method for efficiently cleaning a LPCVD furnace tube for polysilicon back seal, using the above-mentioned efficient cleaning device for LPCVD furnace tube for polysilicon back seal, comprising the following steps:

[0010] S1, placing the inner tube Tube-1 and the outer tube Tube-2 of the LPCVD in the two cleaning tanks of the furnace tube cleaning machine respectively for washing with high-purity deionized water;

[0011] S2, soaking the rinsed furnace tubes in a mixed acid solution of a certain concentration;

[0012] S3, using high-purity deionized water to spray and clean the furnace tubes after being soaked in mixed acid;

[0013] S4, soaking the furnace tube after the mixed acid soaking in a DHF solution of a certain concentration;

[0014] S5. The furnace tubes soaked in the DHF solution are sprayed and cleaned with high-purity deionized water;

[0015] S6, rinse the furnace tube with pure water and use N 2 Blow dry;

[0016] S7. Perform surface inspection on the dried furnace tube.

[0017] As a further improvement of the technical solution, the LPCVD is used for polycrystalline back sealing of silicon substrate, and the main reactant in the reaction process is SiH 4 The reactant residues on the furnace tube surface are mainly polycrystalline silicon.

[0018] As a further improvement of the technical solution, in S1, the material of Tube-1 is mainly high-purity silicon carbide, and the material of Tube-2 is mainly high-purity quartz. During the assembly process, Tube-1 is placed in Tube-2.

[0019] As a further improvement of the technical solution, in S2, the mixed acid solution components are HF, HAC, HNO 3 , H 2 O;

[0020] The mixed acid concentrations are divided into two categories. The mixed acid concentrations used for Tube-1 cleaning are HF: 2% to 5%, HAC: 8% to 15%, and HNO 3 :25%~35%, the rest is H 2 O; the mixed acid concentration used for Tube-2 cleaning is HF: 3% ~ 8%, HAC: 12% ~ 19%, HNO 3 :35%~45%, the rest is H 2 O;

[0021] The mixed acid soaking time is 10min to 40min;

[0022] During the soaking process, the furnace tube is placed on a roller rack in a cleaning tank of a furnace tube cleaning machine at a rotation speed of 5 to 12 r / min.

[0023] As a further improvement of the technical solution, in S3 and S5, the deionized water spraying time is 30 to 45 minutes.

[0024] As a further improvement of the technical solution, in S4, the cleaning liquid is HF and H 2 O mixed solution, HF concentration is 0.1% ~ 0.5%, the immersion time is 20min ~ 40min, during the immersion process, the furnace tube is placed on the roller rack in the cleaning tank of the furnace tube cleaning machine, and the rotation speed is 5 ~ 12r / min;

[0025] The inner wall brush is made of polytetrafluoroethylene;

[0026] The inner wall brush has a rotation speed of 35 to 40 r / min, and the outer wall brush has a rotation speed of 55 to 60 r / min.

[0027] As a further improvement of the technical solution, in S6, the N 2The purge flow rate is 5 to 20 L / min, and the purge time is 60 to 120 min.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] In the high-efficiency cleaning method and device for LPCVD furnace tubes for polysilicon back sealing, the inner tube and the outer tube of the low-pressure vapor deposition furnace (LPCVD) are respectively cleaned with high-purity deionized water, cleaned with mixed acid solution, cleaned with high-purity deionized water, cleaned with DHF, cleaned with high-purity deionized water, and cleaned with N 2 Purge drying, tube wall thickness and particle detection; wherein, the LPCVD inner tube is made of silicon carbide and the outer tube is made of quartz, and the cleaning process mainly removes impurities such as polysilicon layer, particles, metal, organic contamination on the surface of the furnace tube by cleaning with mixed acid, DHF and deionized water; the method is simple to operate, has significant effect and strong flexibility, and can effectively remove impurities such as polysilicon layer and particles generated quickly on the surface of the LPCVD furnace tube during the reaction without damaging the furnace tube surface, and can significantly extend the service life of the furnace tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of a top view of the LPCVD furnace tube and brush in an exemplary cleaning tank of the present invention;

[0031] Figure 2 It is a schematic diagram of the side view structure of the LPCVD furnace tube and brush in the cleaning tank of the present invention;

[0032] Figure 3 Schematic diagram of an exemplary LPCVD furnace tube cleaning method of the present invention;

[0033] Figure 4 This is a flowchart of an exemplary embodiment 1 of the present invention;

[0034] Figure 5 This is a flow chart of an exemplary comparative example 2 of the present invention;

[0035] Figure 6 This is a flow chart of an exemplary comparative example 3 of the present invention;

[0036] Figure 7 This is a flow chart of an exemplary comparative example 4 of the present invention;

[0037] Figure 8 This is a flow chart of an exemplary comparative example 5 of the present invention;

[0038] In the figure:

[0039] 1. Cleaning tank; 2. LPCVD furnace tube; 3. Inner wall brush; 4. Inner wall brush rotating shaft; 5. Side wall brush rotating shaft; 6. Side wall brush; 7. Furnace tube rotating roller. DETAILED DESCRIPTION

[0040] 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 present 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.

[0041] Example

[0042] like Figure 1-Figure 2 As shown, this embodiment provides a high-efficiency cleaning device for LPCVD furnace tubes for polysilicon back sealing, including a furnace tube cleaning machine, in which two cleaning tanks 1 of the same structure are arranged, in which an inner wall brush shaft 4 and a side wall brush shaft 5 are connected and rotated side by side, an inner wall brush 3 is arranged on an outer fixed sleeve of the inner wall brush shaft 4, and an outer wall brush 6 is arranged on an outer fixed sleeve of the side wall brush shaft 5, and at least two furnace tube rotating rollers 7 are distributed in a circular arc at the lower end of the interior of the cleaning tank 1 below the inner wall brush shaft 4.

[0043] Furthermore, the cleaning tank 1 is made of polytetrafluoroethylene, and a transverse entry and exit structure for accommodating the entry and exit of the LPCVD furnace tube 2 is provided at one end of the cleaning tank 1 corresponding to the inner wall brush shaft 4, so as to facilitate the entry and exit and loading and unloading of the LPCVD furnace tube 2.

[0044] Furthermore, the arc surface where the plurality of furnace tube rotating rollers 7 are located is arranged concentrically with the center line of the inner wall brush rotating shaft 4, the outer diameter of the inner wall brush 3 is adapted to the inner diameter of the LPCVD furnace tube 2, and the minimum distance between the inner wall brush 3 and the outer wall brush 6 is adapted to the tube wall thickness of the LPCVD furnace tube 2;

[0045] When the LPCVD furnace tube 2 is sleeved on the outside of the inner wall brush shaft 4 and placed on a number of furnace tube rotating rollers 7, the inner wall brush 3 and the outer wall brush 6 are in contact with the inner and outer walls of the LPCVD furnace tube 2 respectively, so as to fully brush and clean the inner and outer walls of the LPCVD furnace tube 2.

[0046] like Figure 3 As shown, this embodiment also provides a method for efficiently cleaning the LPCVD furnace tube for polysilicon back seal, using the above-mentioned efficient cleaning device for the LPCVD furnace tube for polysilicon back seal, comprising the following steps:

[0047] S1, placing the inner tube Tube-1 and the outer tube Tube-2 of LPCVD in two cleaning tanks 1 of the furnace tube cleaning machine for high-purity deionized water washing; wherein, LPCVD is used for silicon substrate polycrystalline back sealing, and the main reaction substance in its reaction process is SiH 4, the reactant residues on the furnace tube surface are mainly polysilicon;

[0048] In this step, the material of Tube-1 is mainly high-purity silicon carbide, and the material of Tube-2 is mainly high-purity quartz. During the assembly process, Tube-1 is placed in Tube-2;

[0049] Among them, the specific operation steps of S1 include: placing the inner tube Tube-1 and the outer tube Tube-2 of the LPCVD on the roller racks in the two cleaning tanks 1 of the furnace tube cleaning machine respectively, installing the inner wall brush 3 and the side wall brush 6 from the side opening of the cleaning tank 1, and using high-purity deionized water to spray and rinse the furnace tube to wash away the surface silicon oxide dust; the roller rack is composed of two furnace tube rotating rollers 7, chains and gears. During cleaning, the gears are driven by a motor to rotate, and the gears drive the furnace tube rotating rollers 7 to rotate through the chains. The furnace tube rotating rollers 7 drive the furnace tube to rotate, with a speed of 5 to 12 r / min, the speed of the inner wall brush 3 is 35 to 40 r / min, and the speed of the outer wall brush 6 is 55 to 60 r / min. The dust on the surface of the furnace tube can be fully washed and removed by rotating and brushing; the rinsing time is 3 to 5 minutes, the rinsing is turned off, and the high-purity deionized water after rinsing is drained, and the drainage time is about 7 to 10 minutes;

[0050] S2, soak the rinsed furnace tubes in a mixed acid solution of a certain concentration; wherein the mixed acid solution comprises HF, HAC, HNO 3 , H 2 O;

[0051] There are two types of mixed acid concentrations. The mixed acid concentrations used for Tube-1 cleaning are HF: 2% to 5%, HAC: 8% to 15%, and HNO 3 :25%~35%, the rest is H 2 O; the mixed acid concentration used for Tube-2 cleaning is HF: 3% ~ 8%, HAC: 12% ~ 19%, HNO 3 :35%~45%, the rest is H 2 O;

[0052] The mixed acid immersion time is 10min to 40min;

[0053] Among them, the preparation steps of the mixed acid solutions of two concentrations are:

[0054] Mixed acid solution used for LPCVD inner tube Tube-1: Prepare the mixed acid solution in the liquid storage tank with the concentration of HF: 2%~5%; HAC: 8%~15%; HNO 3 :25%~35%; the rest is H 2 O;

[0055] Mixed acid solution used for LPCVD inner tube Tube-2: Prepare the mixed acid solution in the liquid storage tank with the concentration of HF: 3%~8%; HAC: 12%~19%; HNO 3 :35%~45%; the rest is H 2 O;

[0056] Use a liquid pump to inject the prepared two mixed acid solutions into the corresponding cleaning tank, with the injection volume being about 85 to 100L;

[0057] During the soaking process, the furnace tube is placed on a roller rack in a cleaning tank of a furnace tube cleaning machine at a rotation speed of 5 to 12 r / min. The cleaning steps are as follows: the furnace tube is soaked in a prepared mixed acid solution for 100 to 240 minutes. During the soaking process, the furnace tube is placed on a roller rack in a cleaning tank 1 of the furnace tube cleaning machine at a rotation speed of 5 to 12 r / min. An inner wall brush 3 is rotated to scrub the inner wall of the furnace tube at a rotation speed of 35 to 40 r / min. A side wall brush 6 is scrubbed on the outer wall of the furnace tube at a rotation speed of 55 to 60 r / min.

[0058] S3, the furnace tubes soaked in mixed acid are sprayed with high-purity deionized water for cleaning; wherein the deionized water spraying time is 30 to 45 minutes; and the water is drained while rinsing to prevent the acid from remaining on the surface of the furnace tubes;

[0059] S4, soaking the furnace tube after the mixed acid soaking in a DHF solution of a certain concentration; the purpose is to rinse the furnace tube and remove the surface metal ions;

[0060] The cleaning fluid is HF and H 2 O mixed solution, HF concentration is 0.1% ~ 0.5%, the immersion time is 20min ~ 40min, during the immersion process, the furnace tube is placed on the roller rack in the cleaning tank of the furnace tube cleaning machine, and the rotation speed is 5 ~ 12r / min;

[0061] The inner wall brush is made of polytetrafluoroethylene;

[0062] The speed of the inner wall brush is 35-40r / min, and the speed of the outer wall brush is 55-60r / min;

[0063] S5. The furnace tubes soaked in the DHF solution are sprayed and cleaned with high-purity deionized water; wherein the deionized water spraying time is 30 to 45 minutes;

[0064] S6, rinse the furnace tube with pure water and use N 2 Purge and dry; wherein N 2 The purge flow rate is 5-20L / min, and the purge time is 60-120min;

[0065] S7. Perform surface inspection on the dried furnace tube.

[0066] Example 1

[0067] like Figure 4 As shown, this embodiment provides an efficient cleaning method for LPCVD furnace tubes for polysilicon back sealing, comprising the following steps:

[0068] S1, placing the inner tube Tube-1 and the outer tube Tube-2 of the LPCVD in two cleaning tanks 1 in the furnace tube cleaning machine for washing with high-purity deionized water;

[0069] S2, soaking the rinsed furnace tubes in a mixed acid solution of a certain concentration;

[0070] S3, using high-purity deionized water to spray and clean the furnace tubes after being soaked in mixed acid;

[0071] S4, soaking the furnace tube after the mixed acid soaking in a DHF solution of a certain concentration;

[0072] S5. The furnace tubes soaked in the DHF solution are sprayed and cleaned with high-purity deionized water;

[0073] S6, rinse the furnace tube with pure water and use N 2 Blow dry;

[0074] S7. Perform surface inspection on the dried furnace tube.

[0075] In S1, the LPCVD inner tube Tube-1 and outer tube Tube-2 are placed on the roller racks in the two cleaning tanks 1 in the furnace tube cleaning machine, the cleaning tank cover is closed, and the cleaning is started. First, the furnace tube is sprayed with high-purity deionized water to wash away the surface dust. At the same time, the roller rack starts to drive the LPCVD silicon carbide tube to rotate at a speed of 12r / min. The inner wall brush 3 rotates and brushes the inner wall of the furnace tube at a speed of 35r / min, and the side wall brush 6 brushes the outer wall of the furnace tube at a speed of 55r / min. Rinse with high-purity deionized water for 5 minutes, and start draining after rinsing. The drainage time is 10 minutes.

[0076] In S2, the furnace tubes rinsed with high-purity deionized water are immersed in a mixed acid solution of a certain concentration for cleaning, and the steps of the mixed acid solution are:

[0077] After the water in S1 is drained, the liquid pump injects the prepared two concentrations of mixed acid solutions into the corresponding cleaning tank 1 respectively. The injection time is 3 minutes and the injection volume is 1 / 3 of the volume of the cleaning tank.

[0078] Cleaning process: The furnace tube is immersed in a mixed acid solution of a certain concentration. The concentration of the inner tube Tube-1 is: HF: 5%; HAC: 15%; HNO 3: 35%; outer tube Tube-2 soaking mixed acid concentration: HF: 8%; HAC: 19%; HNO 3 :45%; the rest is H 2 O; the soaking time of inner tube Tube-1 is 240min, and the soaking time of outer tube Tube-2 is 120min. During the soaking process, the furnace tube is placed on the roller frame in the cleaning tank 1 of the furnace tube cleaning machine, with a rotation speed of 12r / min, the inner wall brush 3 rotates and brushes the inner wall of the furnace tube, the brush speed is 40r / min, and the side wall brush 6 brushes the outer wall of the furnace tube, the brush speed is 60r / min, and the polysilicon layer on the inner wall of the furnace tube is corroded and cleaned by the mixed acid solution. After the cleaning is completed, the cleaning tank valve is opened to return the mixed acid solution to the liquid storage tank. Then use high-purity deionized water to rinse the cleaning tank 1 and the pipeline.

[0079] In S3, high-purity deionized water is used to rinse the furnace tubes after being soaked in the mixed acid in S2. The water is quickly drained immediately after rinsing and the rinsing is repeated for 45 minutes to prevent the acid from remaining on the surface of the furnace tubes.

[0080] In S4, the furnace tube rinsed with high-purity deionized water is soaked in a DHF solution of a certain concentration to rinse the furnace tube and remove surface metal ions; the DHF solution is HF and H 2 O mixed solution, HF concentration is 0.5%, immersion time is 40min, during the immersion process, the furnace tube is placed on the roller rack in the cleaning tank 1 of the furnace tube cleaning machine.

[0081] In S5, the furnace tubes soaked in the DHF solution are sprayed and rinsed with high-purity deionized water for 45 minutes.

[0082] In S6, the furnace tubes rinsed with high-purity deionized water are washed with N 2 Purge drying was performed with a purge flow rate of 20 L / min and a purge time of 120 min.

[0083] S7 Lieutenant General N 2 The LPCVD furnace tube 2 after purging and drying is subjected to surface inspection.

[0084] Comparative Example 2

[0085] like Figure 5 As shown, in Comparative Example 2, compared with Example 1, only the concentration of the mixed acid solution is replaced by HF: 10%; HAC: 20%; HNO 3 :20%; the rest is H 2 O, the other steps are exactly the same.

[0086] Comparative Example 3

[0087] like Figure 6As shown, in Comparative Example 3, compared with Example 1, only the concentration of the mixed acid solution is replaced by HF: 10%; HAC: 30%; HNO 3 :10%; the rest is H 2 O, the other steps are exactly the same.

[0088] Comparative Example 4

[0089] like Figure 7 As shown, in Comparative Example 4, compared with Example 1, only the concentration of the mixed acid solution is replaced by HF: 5%; HAC: 25%; HNO 3 :15%; the rest is H 2 O, the other steps are exactly the same.

[0090] Comparative Example 5

[0091] like Figure 8 As shown, compared with Example 1, Comparative Example 5 only does not use a brush for scrubbing, and the mixed acid immersion time is changed to 240 minutes.

[0092] Performance Testing

[0093] (1) Using a thickness gauge to measure the thickness of the furnace tube wall before and after cleaning (measure 5 points and take the average value), compare it with the thickness of the furnace tube before the polysilicon layer is deposited, and calculate the polysilicon layer thickness removal rate;

[0094] (2) Use an OLYMPUS metallographic microscope to observe the number of particles with a particle size of ≤0.3 μm on the surface of the furnace tube after cleaning, and calculate the particle removal rate;

[0095] Table 1: Comparative statistics of Example 1 and Comparative Examples 2-5

[0096] Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Polysilicon layer thickness removal rate (%) 99.5 97.3 98.6 97.1 99.2 Surface particle removal rate (%) 99.8 98.7 98.1 96.8 99.5

[0097] It can be seen from Table 1 that the maintenance method of the present application has the advantages of high polysilicon layer thickness removal rate, fast polysilicon layer removal rate and high surface particle removal rate.

[0098] In summary, the LPCVD furnace tube cleaned using the method of this scheme:

[0099] (1) The polysilicon layer thickness removal rate can reach 99%;

[0100] (2) The polysilicon layer removal time can be shortened by 2 hours;

[0101] (3) The surface particle removal rate can reach 99%.

[0102] Those skilled in the art will appreciate that the process of implementing all or part of the steps of the above embodiments may be completed by hardware, or may be completed by instructing related hardware through a program.

[0103] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An efficient cleaning device for LPCVD furnace tubes for polysilicon back seal, characterized in that: The invention comprises a furnace tube cleaning machine, wherein two cleaning tanks (1) of the same structure are arranged inside the cleaning tank, an inner wall brush rotating shaft (4) and a side wall brush rotating shaft (5) are rotatably connected side by side inside the cleaning tank (1), an inner wall brush (3) is arranged on the outer fixed sleeve of the inner wall brush rotating shaft (4), an outer wall brush (6) is arranged on the outer fixed sleeve of the side wall brush rotating shaft (5), and at least two furnace tube rotating rollers (7) are distributed in an arc shape at the lower end of the cleaning tank (1) below the inner wall brush rotating shaft (4).

2. The high-efficiency cleaning device for LPCVD furnace tubes for polysilicon back seal according to claim 1 is characterized in that: The cleaning tank (1) is made of polytetrafluoroethylene, and a lateral entry and exit structure for accommodating the entry and exit of the LPCVD furnace tube (2) is provided at one end of the cleaning tank (1) corresponding to the inner wall brush shaft (4).

3. The high-efficiency cleaning device for LPCVD furnace tubes for polysilicon back seal according to claim 2, characterized in that: The arc surface where the furnace tube rotating rollers (7) are located is cocentrically arranged with the center line of the inner wall brush rotating shaft (4); the outer diameter of the inner wall brush (3) is matched with the inner diameter of the LPCVD furnace tube (2); the minimum distance between the inner wall brush (3) and the outer wall brush (6) is matched with the tube wall thickness of the LPCVD furnace tube (2); when the LPCVD furnace tube (2) is sleeved on the outer side of the inner wall brush rotating shaft (4) and placed on the furnace tube rotating rollers (7), the inner wall brush (3) and the outer wall brush (6) are in contact with the inner and outer walls of the LPCVD furnace tube (2) respectively.

4. A highly efficient cleaning method for LPCVD furnace tubes used for polycrystalline silicon back seals, using the highly efficient cleaning device for LPCVD furnace tubes used for polycrystalline silicon back seals as claimed in any one of claims 1 to 3, characterized in that: The steps include: S1, placing the inner tube Tube-1 and the outer tube Tube-2 of the LPCVD in the two cleaning tanks (1) in the furnace tube cleaning machine respectively for washing with high-purity deionized water; S2, soaking the rinsed furnace tubes in a mixed acid solution of a certain concentration; S3, using high-purity deionized water to spray and clean the furnace tubes after being soaked in mixed acid; S4, soaking the furnace tube after the mixed acid soaking in a DHF solution of a certain concentration; S5. The furnace tubes soaked in the DHF solution are sprayed and cleaned with high-purity deionized water; S6, using N2 to purge and dry the furnace tube after being rinsed with pure water; S7. Perform surface inspection on the dried furnace tube.

5. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: The LPCVD is used for polycrystalline back sealing of silicon substrates. The main reaction substance in the reaction process is SiH4, and the reactant residues on the surface of the furnace tube are mainly polycrystalline silicon.

6. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: In S1, the material of Tube-1 is mainly high-purity silicon carbide, and the material of Tube-2 is mainly high-purity quartz. During the assembly process, Tube-1 is placed in Tube-2.

7. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: In S2, the mixed acid solution components are HF, HAC, HNO3, and H2O; The mixed acid concentration is divided into two categories. The mixed acid concentration used for cleaning Tube-1 is HF: 2% to 5%, HAC: 8% to 15%, HNO3: 25% to 35%, and the rest is H2O; the mixed acid concentration used for cleaning Tube-2 is HF: 3% to 8%, HAC: 12% to 19%, HNO3: 35% to 45%, and the rest is H2O; The mixed acid soaking time is 10min to 40min; During the soaking process, the furnace tube is placed on a roller rack in a cleaning tank of a furnace tube cleaning machine at a rotation speed of 5 to 12 r / min.

8. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: In S3 and S5, the deionized water spraying time is 30 to 45 minutes.

9. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: In S4, the cleaning liquid is a mixture of HF and H2O, the HF concentration is 0.1% to 0.5%, the immersion time is 20min to 40min, and during the immersion process, the furnace tube is placed on a roller rack in the cleaning tank of the furnace tube cleaning machine at a rotation speed of 5 to 12r / min; The inner wall brush is made of polytetrafluoroethylene; The inner wall brush has a rotation speed of 35 to 40 r / min, and the outer wall brush has a rotation speed of 55 to 60 r / min.

10. The high-efficiency cleaning method for LPCVD furnace tubes used for polysilicon back sealing according to claim 4, characterized in that: In S6, the N2 purge flow rate is 5 to 20 L / min, and the purge time is 60 to 120 min.

Images