Device and method for automatically powdering silicon wafers

Abstract

The present invention provides a device and method for automatic powdering of silicon wafers. The device includes: a transmission device, a powdering plate, and a powdering device; wherein the powdering device is used to coat glass paste on the silicon wafer, and the powdering device includes an ultrasonic device and a storage tank, the storage tank is used to contain the glass paste, and the ultrasonic device is used to ultrasonically process the material in the storage tank; the transmission device is used to transfer the silicon wafer, to send the silicon wafer into the glass paste in the storage tank, and to remove the powdered silicon wafer from the glass paste, and to remove the excess glass paste on the surface of the silicon wafer after powdering through the powdering plate. The present invention also provides an automatic powdering method performed by the above-mentioned automatic powdering device. The automatic powdering device and method of the present invention has uniform coating of the glass film, better protection of the passivation area, high degree of automation, and high efficiency.

Description

Technical Field

[0001] The invention relates to a device and method for automatically powdering a silicon wafer when preparing a glass passivation diode, and belongs to the technical field of preparing glass passivation diodes. Background Art

[0002] GPP is a general term for glass passivated devices, and now refers to glass passivated diodes. Glass passivated diodes are mainly made of single crystal silicon wafers, which are processed through diffusion, photolithography etching, scraping, clearing, grooving, debonding, powdering, passivation, sintering, spot testing, cutting, and cleaving.

[0003] In the preparation process of glass passivated diodes, powder coating is an important step that directly affects the quality of glass passivated diodes. The existing silicon wafer powder coating methods mainly include scalpel method, electrophoresis method, and photoresist method.

[0004] Among them, the surgical knife method is to use a plastic rod to pick up the glass paste, scrape the glass paste into the groove with a blade, then remove organic matter at low temperature, wipe the surface glass film, and then sinter at high temperature. This method has uneven coating and easy scratches on the surface. It is a labor-intensive operation mode with high labor intensity.

[0005] The electrophoresis method is to evenly mix the glass powder in acetone by ultrasound, irradiate the glass powder with a lamp, increase the activity of the charged particles in the glass powder, and under the action of the electric field, move to the exposed silicon in a directional manner, and then cover the groove, and then sinter at high temperature to play a passivation role. This method has a protrusion at the edge of the groove, which affects the packaging and subsequent product process (the protrusion causes the photomask to break). The process has high requirements on the surface of the silicon wafer, and it is easy to electrophoresed in areas that do not need electrophoresis, and the thickness of the glass film is uneven.

[0006] The photoresist method is to mix glass powder and photoresist evenly, and then evenly coat them on the surface and groove of the silicon wafer by spin coating. Unnecessary glass film and photoresist are removed by photolithography exposure and development, and the residual photoresist in the glass film is removed by subsequent sintering to achieve passivation of the glass film. However, the process of this method is complicated and the photolithography process is not easy to control. Summary of the invention

[0007] In view of the above problems existing in the prior art, the object of the present invention is to provide a method for automatically powdering a silicon wafer, which has the advantages of uniform glass film coating, good protection of the passivation area and is not easy to scratch the surface.

[0008] Another object of the present invention is to provide an automatic powder loading device for use in the above-mentioned silicon wafer automatic powder loading method.

[0009] In order to achieve the above-mentioned object, the present invention first provides a device for automatically applying powder to silicon wafers, the device comprising: a transmission device, a powder scraper, and a powder applying device; wherein:

[0010] The powder coating equipment is used to coat the glass paste on the silicon wafer, and the powder coating equipment includes an ultrasonic device and a storage tank, the storage tank is used to contain the glass paste, and the ultrasonic device is used to ultrasonically process the material in the storage tank;

[0011] The transmission equipment is used to transport silicon wafers, to send the silicon wafers into the glass paste in the storage tank, and to remove the powdered silicon wafers from the glass paste, and to remove the excess glass paste on the surface of the silicon wafers after powdering through a powder scraper.

[0012] In a specific embodiment of the present invention, the transmission device includes two rotating wheels and a conveyor belt, wherein the rotating wheels drive the conveyor belt to transmit; the conveyor belt is used to transmit silicon wafers. The conveyor belt is a belt made of polytetrafluoroethylene; the silicon wafer is fixed on the conveyor belt, and the fixing method can be vacuum adsorption or mechanical clamping.

[0013] In a specific embodiment of the present invention, the ultrasonic device is mainly used to remove bubbles in the silicon wafer groove and fill the uniform glass paste into the groove of the silicon wafer. Specifically, the storage tank can be arranged inside the ultrasonic device. The storage tank can be a quartz cylinder. The storage tank is arranged between two rotating wheels. At least two pulleys are arranged in the storage tank, and the pulleys are used to make the conveyor belt pass through the glass paste.

[0014] In a specific embodiment of the present invention, a scraper plate is arranged between the rotating wheel and the storage tank, and the length of the scraper plate is 12cm-15cm, the width is 1cm-2cm, and the height is 1.5cm-3cm; wherein, the scraper plate can be an elastic plastic plate; the device can also include a bracket for loading the scraper plate; wherein, the bracket can be a stainless steel bracket.

[0015] In a specific embodiment of the present invention, the glass paste is composed of glass powder and butyl carbitol in a mass ratio of 1-3:1.

[0016] The present invention also provides a method for automatically powdering a silicon wafer using the above-mentioned device for automatically powdering a silicon wafer. The method comprises:

[0017] The silicon wafer is sent into the storage tank filled with glass paste by a conveyor belt, and the running distance of the silicon wafer in the glass paste is 8cm-12cm. The bubbles in the silicon wafer groove are effectively removed by ultrasound, and the glass paste is evenly filled into the silicon wafer groove; the running speed of the conveyor belt is 1mm / sec-3mm / sec; the ultrasonic power is 20MHz-80MHz, and the current is 0.5A-3A;

[0018] The silicon wafer is loaded on a conveyor belt and passed through a powder scraper to remove excess glass paste from the surface of the silicon wafer;

[0019] The silicon wafer is subjected to low temperature treatment to remove organic matter (butyl carbitol) in the glass paste;

[0020] Then high-temperature sintering is carried out to complete the automatic powdering of the silicon wafer.

[0021] In a specific embodiment of the present invention, the speed at which the silicon wafer passes through the scraper is the same as the speed at which the silicon wafer passes through the storage tank. Specifically, the silicon wafer is directly taken off the conveyor belt after passing through the scraper for subsequent steps.

[0022] In a specific embodiment of the present invention, the time of low temperature treatment is 10 min-40 min; the temperature of low temperature treatment is 400° C.-500° C.

[0023] In a specific embodiment of the present invention, the high temperature sintering time is 8 min-30 min, and the high temperature sintering temperature is 650°C-900°C.

[0024] In a specific embodiment of the present invention, before high-temperature sintering, the glass paste on the surface of the silicon wafer is wiped with plastic fibers to remove the glass paste.

[0025] The present invention further provides a GPP (glass passivated diode), the preparation of which includes the steps described in the method for automatic powdering of silicon wafers of the present invention.

[0026] The device and method for automatically powdering a silicon wafer of the present invention are particularly suitable for powdering a silicon wafer with grooves dug on one side.

[0027] The glass film of the device and method for automatically powdering silicon wafers of the present invention is coated evenly, and the passivation area is well protected; the requirements for the surface of the silicon wafer are relatively low, and the surface is not easily scratched; the automation degree is high, and the efficiency is high.

[0028] The automatic powdering method for silicon wafers of the present invention has simple process and strong operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the device for automatically powdering silicon wafers in Example 1 of the present invention.

[0030] Figure 2a Schematic diagram of the silicon wafer after powder coating in Example 1 of the present invention.

[0031] Figure 2b Schematic diagram of the silicon wafer after powder coating in Example 1 of the present invention.

[0032] Description of main figures:

[0033] 1. Conveyor belt; 2. Storage tank; 3. Ultrasonic equipment; 4. Rotating wheel; 5. Scraper plate; 6. Pulley; A and B represent the moving path of the silicon wafer. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0035] Example 1

[0036] This embodiment provides a device for automatically powdering a silicon wafer, which has the following features: Figure 1 The structure shown in the figure comprises: a transmission device, a powder scraper 5, and a powder applying device.

[0037] The powder coating device is used to coat the glass paste on the silicon wafer, and the powder coating device includes an ultrasonic device 3 and a storage tank 2. The storage tank 2 is used to contain the glass paste, and the ultrasonic device 3 is used to ultrasonically process the material in the storage tank, remove the bubbles in the silicon wafer groove, and fill the uniform glass paste into the groove of the silicon wafer. The storage tank 2 can be arranged inside the ultrasonic device 3, and the storage tank 2 is arranged between two rotating wheels 4. Two pulleys 6 are arranged in the storage tank 2, and the pulleys 6 are used to make the conveyor belt 1 pass through the glass paste. The storage tank 2 can be a quartz cylinder.

[0038] The transmission device is used to transport silicon wafers, to send the silicon wafers into the glass paste in the storage tank 2, and to take the powdered silicon wafers out of the glass paste, and to remove the excess glass paste on the surface of the silicon wafers after the powdering through the powder scraper 5.

[0039] The transmission device includes two rotating wheels 4 and a conveyor belt 1. The rotating wheels 4 drive the conveyor belt 1 to move. The conveyor belt 1 is used to transport silicon wafers. The conveyor belt 1 is a belt made of polytetrafluoroethylene. The silicon wafer is fixed on the conveyor belt 1, and the fixing method can be vacuum adsorption or mechanical clamping.

[0040] The scraper plate 5 is arranged between the rotating wheel 4 and the storage tank 2 and fixed by a bracket, which can be a stainless steel bracket. The scraper plate 5 has a length of 12cm-15cm, a width of 1cm-2cm, and a height of 1.5cm-3cm; wherein the scraper plate 5 can be an elastic plastic plate.

[0041] This embodiment also provides a method for automatically powdering a silicon wafer using the above device, which specifically includes:

[0042] By photolithography, the areas that do not need to be grooved are protected;

[0043] The PN junction of the silicon wafer is cut off by acid corrosion to form a clean PN junction section. The acid solution used is HF:HNO3=1:1.5;

[0044] Load the silicon wafer into Figure 1In the device shown in the figure, the groove produced by etching is required to be at an angle of 15° to the belt running track. The silicon wafer is fed into the glass paste through the conveyor belt, and the silicon wafer moves to Figure 1 At position A shown in the figure, (the glass paste is composed of glass powder and butyl carbitol in a mass ratio of 1:1 in a storage tank, and the silicon wafer is moved in the glass paste at a speed of 1 mm / sec for a distance of 8 cm, and the bubbles in the silicon wafer groove are removed by ultrasound, and the glass paste is evenly filled into the silicon wafer groove, so that the etched groove is filled with glass paste; the ultrasonic power is 20 MHz, and the current is 0.5 A;

[0045] After the silicon wafers are transported out of the storage tank via the conveyor belt, they are wiped off the glass paste on the surface of the silicon wafers by a scraper (the scraper is at an angle of 15° to the silicon wafer slot to avoid affecting the glass film in the slot). Figure 1 The silicon wafer is then taken out of the position B shown in the figure; (in the actual process, multiple silicon wafers are continuously reciprocated);

[0046] The silicon wafers were loaded into a quartz boat and placed in a furnace for low-temperature sintering at 400°C for 10 minutes to remove the organic solvent and roughly solidify the glass film.

[0047] By using an eraser, further erase the remaining glass paste on the surface of the silicon wafer (retaining the glass powder in the groove);

[0048] The powdered silicon wafer is loaded into a quartz boat and placed into a furnace for low-temperature sintering at 650°C for 8 minutes. After the softening temperature and flow temperature of the glass powder, the glass paste is finally shaped to achieve passivation protection for the PN junction, completing the automatic powdering of the silicon wafer.

[0049] The automatic powder loading device can reduce the labor intensity of employees and improve production efficiency. Figure 2a and Figure 2b As shown. Figure 2a and Figure 2b It can be seen that the automatic powder-coating device avoids abnormal scratches on the silicon wafer surface caused by uneven manual force during the powder-coating process, improves the consistency of the glass paste in the tank, and the repeatability between silicon wafers.

[0050] Example 2

[0051] This embodiment provides a Figure 1 The automatic powdering method performed by the device shown specifically includes:

[0052] By photolithography, the areas that do not need to be grooved are protected;

[0053] The PN junction of the silicon wafer is cut off by acid corrosion to form a clean PN junction section. The acid solution used is HF:HNO3=1:3;

[0054] Load the silicon wafer into Figure 1 In the device shown, the groove produced by etching is required to form an angle of 75° with the running track of the belt. The silicon wafer is sent into a storage tank filled with glass paste (the glass paste is composed of glass powder and butyl carbitol with a mass ratio of 3:1) through a conveyor belt, and the silicon wafer runs in the glass paste at a speed of 3 mm / sec. The distance is 12 cm, and the bubbles in the silicon wafer groove are removed by ultrasound, and the glass paste is evenly filled into the silicon wafer groove, so that the etched groove is filled with glass paste; the ultrasonic power is 80 MHz, and the current is 3 A;

[0055] After the silicon wafers are transported out of the storage tank via the conveyor belt, they are wiped off the glass paste on the surface of the silicon wafers by a scraper (the scraper is at a 75° angle to the silicon wafer slot to avoid affecting the glass film in the slot), and then the silicon wafers are taken out; (In the actual process, multiple silicon wafers are continuously reciprocated).

[0056] The removed silicon wafer is loaded into a quartz boat and placed into a furnace tube for low-temperature sintering at a temperature of 500°C for 40 minutes to remove the organic solvent and roughly solidify the glass film;

[0057] By using an eraser, further erase the remaining glass paste on the surface of the silicon wafer (retaining the glass powder in the groove);

[0058] The powdered silicon wafer is loaded into a quartz boat and placed into a furnace for low-temperature sintering at 900°C for 30 minutes. After the softening temperature and flow temperature of the glass powder, the glass paste is finally shaped to achieve passivation protection for the PN junction, completing the automatic powdering of the silicon wafer.

[0059] Example 3

[0060] This embodiment provides a Figure 1 The automatic powdering method performed by the device shown specifically includes:

[0061] By photolithography, the areas that do not need to be grooved are protected;

[0062] The PN junction of the silicon wafer is cut off by acid corrosion to form a clean PN junction section. The acid solution used is HF:HNO3=1:3;

[0063] Load the silicon wafer into Figure 1In the device shown, the groove produced by etching is required to be at an angle of 45° to the running track of the belt. The silicon wafer is sent into a storage tank filled with glass paste (the glass paste is composed of glass powder and butyl carbitol in a mass ratio of 3:1) through a conveyor belt, and the silicon wafer runs in the glass paste at a speed of 2 mm / sec. The distance is 12 cm, and the bubbles in the silicon wafer groove are removed by ultrasound, and the glass paste is evenly filled into the silicon wafer groove, so that the etched groove is filled with glass paste; the ultrasonic power is 60 MHz, and the current is 3 A;

[0064] After the silicon wafers are transported out of the storage tank via the conveyor belt, they are wiped off the glass paste on the surface of the silicon wafers by a scraper (the scraper is at a 55° angle to the silicon wafer slot to avoid affecting the glass film in the slot), and then the silicon wafers are taken out; (In the actual process, multiple silicon wafers are continuously reciprocated).

[0065] The removed silicon wafer is loaded into a quartz boat and placed into a furnace tube for low-temperature sintering at a temperature of 500°C for 40 minutes to remove the organic solvent and roughly solidify the glass film;

[0066] By using an eraser, further erase the remaining glass paste on the surface of the silicon wafer (retaining the glass powder in the groove);

[0067] The powdered silicon wafer is loaded into a quartz boat and placed into a furnace for low-temperature sintering at 900°C for 30 minutes. After the softening temperature and flow temperature of the glass powder, the glass paste is finally shaped to achieve passivation protection for the PN junction, completing the automatic powdering of the silicon wafer.

Claims

1. A device for automatically powdering a silicon wafer, the device comprising: Conveying equipment, powder scraper, powder coating equipment; among them, The powder coating device is used to coat the glass paste on the silicon wafer. The powder coating device includes an ultrasonic device and a storage tank. The storage tank is used to contain the glass paste. The ultrasonic device is used to ultrasonically process the material in the storage tank, remove the bubbles in the silicon wafer groove, and fill the uniform glass paste into the groove of the silicon wafer. The storage tank is arranged inside the ultrasonic device and between two rotating wheels. Two pulleys are arranged in the storage tank, and the pulleys are used to allow the conveyor belt to pass through the glass paste. The transmission equipment is used to transport silicon wafers, to send silicon wafers into the glass paste in the storage tank, and to take the powdered silicon wafers out of the glass paste, and to remove the excess glass paste on the surface of the silicon wafers after powdering through the powder scraper; The transmission device includes two rotating wheels and a conveyor belt, and the rotating wheels drive the conveyor belt to move; The conveyor belt is used to transport silicon wafers; the silicon wafers are fixed on the conveyor belt.

2. The device according to claim 1, wherein: The conveyor belt is a belt made of polytetrafluoroethylene.

3. The device according to claim 1, wherein: The length of the scraper board is 12cm-15cm, the width is 1cm-2cm, and the height is 1.5cm-3cm.

4. A method for automatically powdering a silicon wafer, the method being accomplished by the device for automatically powdering a silicon wafer as claimed in any one of claims 1 to 3.

5. The method according to claim 4, wherein: The method includes: The silicon wafer is sent into a storage tank filled with glass paste by a conveyor belt, and the running distance of the silicon wafer in the glass paste is 8cm-12cm. The bubbles in the silicon wafer groove are removed by ultrasound, and the glass paste is evenly filled into the silicon wafer groove; the running speed of the conveyor belt is 1mm / sec-3mm / sec; the ultrasonic power is 20-80MHz, and the current is 0.5-3A; The silicon wafer is passed through a powder scraper by a conveyor belt to remove excess glass paste from the surface of the silicon wafer; Low temperature treatment of silicon wafers to remove organic matter in the glass paste; High temperature sintering is carried out to complete the automatic powdering of silicon wafers.

6. The method according to claim 5, wherein: The time of low temperature treatment is 10min-40min; the temperature of low temperature treatment is 400℃-500℃.

7. The method according to claim 5, wherein: The high temperature sintering time is 8min-30min, and the high temperature sintering temperature is 650℃-900℃.

8. The method according to claim 5, wherein: The glass paste is composed of glass powder and butyl carbitol in a mass ratio of 1-3:1.

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