Powder coating method for mesa silicon controlled rectifier glass passivation layer

Abstract

The invention discloses a powdering method for a mesa silicon controlled rectifier glass passivation layer. The powdering method specifically comprises the following steps: S1, fixing a silicon wafer on a rotating platform and setting the rotating speed; s2, powdering the silicon wafer for the first time, drying the silicon wafer, wiping powder and feeding the silicon wafer into a furnace; s3, powdering the silicon wafer for the second time, drying the silicon wafer, wiping powder and feeding the silicon wafer into the furnace; through the process design of two times of powdering, two times of drying and two times of furnace entering, the glass powder slurry is loaded by using a small spoon, drips to the surface of the silicon wafer and is uniformly smeared, so that the uniform distribution of the glass powder and a high-quality passivation layer are realized, and meanwhile, the process requirements of no powder falling and no surface residue are met; the defects of surface microdefects, material waste, poor process controllability and the like existing in a traditional scalpel blade coating mode are overcome, meanwhile, the technical difficulties that glass powder slurry is high in adhesion and poor in fluidity are overcome, uniform distribution of glass powder is achieved, and the quality and production efficiency of a tabletop silicon controlled rectifier glass passivation layer are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and particularly to a method for applying powder to a mesa thyristor glass passivation layer. Background Art

[0002] The glass passivation layer of a thyristor is an insulating protective layer used to protect the surface of a semiconductor chip, usually made of glass materials (such as lead silicate, borosilicate, etc.), and covering the PN junction and the edges of metal electrodes of the chip.

[0003] Deficiencies of the prior art:

[0004] Currently, the method for applying glass powder uses a scalpel scraping method. When scraping with a scalpel, the blade directly contacts the surface of the silicon wafer, which easily leaves scratches or scuffs on the glass powder layer or the surface of the silicon wafer. The glass powder slurry is unevenly distributed during scraping, and differences in manual techniques result in unstable product quality. Moreover, the adhesiveness of the glass powder slurry is relatively high, making it difficult to be evenly distributed by traditional means, greatly affecting product quality and production efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for applying powder to a mesa thyristor glass passivation layer to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A method for applying powder to a mesa thyristor glass passivation layer, the powder application method specifically includes the following steps:

[0007] S1. Fix the silicon wafer on a rotating platform and set the rotation speed;

[0008] S2. Apply powder to the silicon wafer for the first time, and then dry, wipe the powder, and send it to the furnace;

[0009] S3. Apply powder to the silicon wafer for the second time, and then dry, wipe the powder, and send it to the furnace.

[0010] Preferably, the step S2 specifically includes the following steps:

[0011] a1. Use a small spoon to load the first glass powder slurry, slowly drip it on the surface of the rotating silicon wafer, and use a spreading tool to spread the glass powder slurry on the surface of the silicon wafer. The rotation speed of the rotating platform can be adjusted during the spreading process;

[0012] a2. After spreading the glass powder slurry, stop the rotating platform, place the silicon wafer after powder application on a high-temperature baking plate for the first drying, so that the first glass powder slurry is initially cured to form a uniform glass liquid;

[0013] a3. Perform the first powder wiping on both sides of the silicon wafer by manual powder wiping;

[0014] a4. Send the silicon wafer after powdering for the first time into the furnace tube to completely solidify the glass liquid.

[0015] Preferably, step S3 specifically includes the following steps:

[0016] b1. Use the same small spoon as in step a1 to load the second glass powder slurry, slowly drop it on the surface of the rotating silicon wafer, and use a spreading tool to spread the glass powder slurry on the surface of the silicon wafer. The rotation speed of the rotating platform can be adjusted during the spreading process;

[0017] b2. After spreading the glass powder slurry, stop the rotating platform, place the silicon wafer after powdering on a high-temperature baking plate for the second drying to preliminarily solidify the second layer of glass liquid;

[0018] b3. Perform the second powdering on both sides of the silicon wafer by manual powdering method;

[0019] b4. Send the silicon wafer after powdering for the second time into the furnace tube to completely solidify the glass liquid to form a glass passivation layer.

[0020] Preferably, in step S1, the rotation speed of the rotating platform is set to 100 - 500 rpm, and the material of the rotating platform is selected from high-temperature resistant and corrosion-resistant materials.

[0021] Preferably, in step a2, the first drying temperature is set to 100 - 300 °C, and the first drying time is set to 3 - 10 min.

[0022] Preferably, in step b2, the second drying temperature is set to 100 - 300 °C, and the second drying time is set to 3 - 10 min.

[0023] Preferably, in step a4, when sending into the furnace tube for the first time, first perform low-temperature solidification and then high-temperature solidification. The low-temperature solidification temperature is set to 300 - 500 °C, the low-temperature solidification time is 10 - 20 min, the high-temperature solidification temperature is set to 600 - 900 °C, and the high-temperature solidification time is 20 - 30 min.

[0024] Preferably, in step b4, when sending into the furnace tube for the second time, first perform low-temperature solidification and then high-temperature solidification. The low-temperature solidification temperature is set to 300 - 500 °C, the low-temperature solidification time is 10 - 20 min, the high-temperature solidification temperature is set to 600 - 900 °C, and the high-temperature solidification time is 20 - 30 min.

[0025] Preferably, in step a1, the material of the small spoon is selected from stainless steel or ceramic materials.

[0026] Preferably, the rotating platform, small spoon, high-temperature baking plate, and furnace tube are all controlled to operate through a connected automated control system.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] The invention provides a method for applying powder to the glass passivation layer of a mesa thyristor. The specific steps include: S1, fixing the silicon wafer on a rotating platform and setting the rotation speed; S2, applying powder to the silicon wafer for the first time, and then drying, wiping the powder, and sending it into the furnace; S3, applying powder to the silicon wafer for the second time, and then drying, wiping the powder, and sending it into the furnace. Through the process design of applying powder twice, drying twice, and feeding into the furnace twice, a small spoon is used to load the glass powder slurry and drip it onto the surface of the silicon wafer and spread it evenly, realizing the uniform distribution of the glass powder and a high-quality passivation layer, and at the same time meeting the process requirements of no powder falling off and no residue on the surface, solving the disadvantages of surface micro-defects, material waste, and poor process controllability existing in the traditional scalpel scraping method. At the same time, it overcomes the technical difficulties of strong adhesion and poor fluidity of the glass powder slurry, realizes the uniform distribution of the glass powder, and improves the quality and production efficiency of the glass passivation layer of the mesa thyristor. Specific embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] In the description of this patent, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "setting" should be understood in a broad sense. For example, it can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0032] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "several" is two or more unless otherwise clearly and specifically defined.

[0033] Embodiment 1

[0034] The technical solution of a method for applying powder to the glass passivation layer of a mesa thyristor provided by the present invention: The powder application method specifically includes the following steps:

[0035] S1, fixing the silicon wafer on a rotating platform and setting the rotation speed. The rotation speed of the rotating platform is set to 200 rpm, and the material of the rotating platform is selected as a high-temperature resistant and corrosion-resistant material;

[0036] S2. Apply powder to the silicon wafer for the first time, then dry, wipe the powder, and send it to the furnace;

[0037] a1. Use a small spoon to load 0.8 g of the first type of glass powder slurry. The material of the small spoon is selected to be heat-resistant or corrosion-resistant, and the spoon mouth is smooth to ensure that the glass powder slurry drips evenly. Slowly drip it onto the surface of the rotating silicon wafer. Under the action of centrifugal force, the glass powder slurry spreads out and is smeared evenly on the surface of the silicon wafer by a smearing tool to ensure that the glass powder slurry evenly covers the surface of the silicon wafer. During the smearing process, the rotation speed of the rotating platform can be adjusted to improve the uniformity of the distribution of the glass powder slurry;

[0038] a2. Stop the rotating platform after smearing the glass powder. Place the silicon wafer after powder application on a high-temperature baking plate for the first drying to make the first glass powder slurry initially solidify to form a uniform glass liquid. The first drying temperature is set at 150 °C, and the first drying time is set at 5 min. The heating method can be selected as electric heating or infrared heating;

[0039] a3. Use a special silicone rubber wiping method by hand to wipe the powder on both sides of the silicon wafer for the first time to ensure that no powder falls out of the groove and there is no glass powder residue on the surface;

[0040] a4. Send the silicon wafer after powder wiping into the furnace tube for the first time to make the glass liquid completely solidify. First, perform low-temperature curing and then high-temperature curing to make the glass liquid completely solidify and tightly combine with the surface of the silicon wafer. The low-temperature curing temperature is set at 400 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set at 800 °C, and the high-temperature curing time is 20 min. The heating method can be selected as resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation;

[0041] S3. Apply powder to the silicon wafer for the second time, then dry, wipe the powder, and send it to the furnace;

[0042] b1. Use the same small spoon as in step a1 to load 1.0 g of the second type of glass powder slurry. The material of the small spoon is selected to be heat-resistant or corrosion-resistant, and the spoon mouth is smooth to ensure that the glass powder slurry drips evenly. The ratio of the second glass powder slurry to the first glass powder slurry is different. Slowly drip it onto the surface of the rotating silicon wafer. Under the action of centrifugal force, the second glass powder slurry spreads out and is smeared evenly on the surface of the silicon wafer by a smearing tool to ensure that the glass powder evenly covers the surface of the silicon wafer. During the smearing process, the rotation speed of the rotating platform can be adjusted to improve the uniformity of the distribution of the glass powder slurry;

[0043] b2. Stop the rotating platform after smearing the glass powder slurry. Place the silicon wafer after powder application on a high-temperature baking plate for the second drying to make the second layer of glass powder slurry initially solidify. The second drying temperature is set at 180 °C, and the second drying time is set at 5 min. The heating method can be selected as electric heating or infrared heating;

[0044] b3. Use a special silicone rubber to manually wipe the wafers on both sides for the second time to ensure that no powder falls out of the tank and there is no residual glass powder on the surface;

[0045] b4. Send the wafers after powder wiping into the furnace tube for the second time to completely solidify the glass liquid to form a glass passivation layer. First, perform low-temperature curing and then high-temperature curing to finally form a high-quality glass passivation layer. The low-temperature curing temperature is set at 450 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set at 850 °C, and the high-temperature curing time is 20 min. The heating method can be selected as resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation.

[0046] Comparative Example 1

[0047] Provide another powdering method:

[0048] S1. Fix the wafer on a rotating platform and set the rotation speed. The rotation speed of the rotating platform is set at 200 rpm, and the material of the rotating platform is selected as a high-temperature and corrosion-resistant material;

[0049] S2. Powder the wafer, and then dry, wipe the powder, and send it to the furnace;

[0050] a1. Use a small spoon to load 0.8 g of glass powder slurry. The material of the small spoon is selected as a high-temperature or corrosion-resistant material, and the spoon mouth is smooth to ensure that the glass powder slurry drips evenly. Slowly drip it on the surface of the rotating wafer. Under the action of centrifugal force, the glass powder slurry scatters and is spread evenly on the surface of the wafer by a spreading tool to ensure that the glass powder slurry evenly covers the surface of the wafer. During the spreading process, the rotation speed of the rotating platform can be adjusted to improve the uniformity of the distribution of the glass powder slurry;

[0051] a2. Stop the rotating platform after spreading the glass powder, and place the wafer after powdering on a high-temperature drying plate for drying to preliminarily solidify the glass powder slurry to form a uniform glass liquid. The drying temperature is set at 150 °C, and the drying time is set at 5 min. The heating method can be selected as electric heating or infrared heating;

[0052] a3. Use a special silicone rubber to manually wipe the wafers on both sides to ensure that no powder falls out of the tank and there is no residual glass powder on the surface;

[0053] a4. Send the wafer after powder wiping into the furnace tube to completely solidify the glass liquid. First, perform low-temperature curing and then high-temperature curing to completely solidify the glass liquid and make it closely combine with the surface of the wafer. The low-temperature curing temperature is set at 400 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set at 800 °C, and the high-temperature curing time is 20 min. The heating method can be selected as resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation.

[0054] Comparative Example 2

[0055] Provide another powdering method:

[0056] S1. Fix the silicon wafer on a rotating platform and set the rotation speed. The rotation speed of the rotating platform is set to 200 rpm, and the material of the rotating platform is selected as a high-temperature resistant and corrosion-resistant material;

[0057] S2. Perform the first powdering on the silicon wafer, and then dry, wipe the powder, and send it to the furnace;

[0058] a1. Use a scalpel to scrape and coat the first type of glass powder slurry on the surface of the silicon wafer, so that the glass powder slurry covers the surface of the silicon wafer;

[0059] a2. Place the powdered silicon wafer on a high-temperature baking plate for the first drying, so that the first glass powder slurry is preliminarily cured to form a uniform glass liquid. The first drying temperature is set to 150 °C, the first drying time is set to 5 min, and the heating method can be selected as electric heating or infrared heating;

[0060] a3. Perform the first powder wiping on both sides of the silicon wafer to ensure that no powder falls out of the groove and there is no glass powder residue on the surface;

[0061] a4. Send the wiped silicon wafer into the furnace tube for the first time to completely cure the glass liquid. First, perform low-temperature curing and then high-temperature curing, so that the glass liquid is completely cured and tightly combined with the surface of the silicon wafer; the low-temperature curing temperature is set to 400 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set to 800 °C, the high-temperature curing time is 20 min, the heating method can be selected as resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation;

[0062] S3. Perform the second powdering on the silicon wafer, and then dry, wipe the powder, and send it to the furnace;

[0063] b1. Use a scalpel to scrape and coat the second type of glass powder slurry on the surface of the silicon wafer, so that the glass powder slurry covers the surface of the silicon wafer;

[0064] b2. Place the powdered silicon wafer on a high-temperature baking plate for the second drying, so that the second layer of glass powder slurry is preliminarily cured. The second drying temperature is set to 180 °C, the second drying time is set to 5 min, and the heating method can be selected as electric heating or infrared heating;

[0065] b3. Perform the second powder wiping on both sides of the silicon wafer to ensure that no powder falls out of the groove and there is no glass powder residue on the surface;

[0066] b4. Send the silicon wafer after powdering into the furnace tube for the second time to completely solidify the glass liquid to form a glass passivation layer. First, perform low-temperature curing and then high-temperature curing to finally form a high-quality glass passivation layer. The low-temperature curing temperature is set at 450 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set at 850 °C, and the high-temperature curing time is 20 min. The heating method can be selected as resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation.

[0067] Comparative Example 3

[0068] Provide another powdering method:

[0069] S1. Fix the silicon wafer on the rotating platform and set the rotation speed. The rotation speed of the rotating platform is set at 200 rpm, and the material of the rotating platform is selected as a high-temperature and corrosion-resistant material.

[0070] S2. Use a small spoon to load 0.8 g of the first glass slurry. The material of the small spoon is selected as a high-temperature or corrosion-resistant material, and the spoon mouth is smooth to ensure that the glass slurry drips evenly. Slowly drip it on the surface of the rotating silicon wafer. Under the action of centrifugal force, the glass slurry spreads out and is evenly smeared on the surface of the silicon wafer by a spreading tool to ensure that the glass slurry evenly covers the surface of the silicon wafer. During the spreading process, the rotation speed of the rotating platform can be adjusted to improve the uniformity of the distribution of the glass slurry.

[0071] S3. After spreading the glass slurry, stop the rotating platform, and place the silicon wafer after powdering on a high-temperature baking plate for the first drying to preliminarily solidify the first glass slurry to form a uniform glass liquid. The first drying temperature is set at 150 °C, and the first drying time is set at 5 min. The heating method can be selected as electric heating or infrared heating.

[0072] S4. Use the powdering method of manually wiping with special silicone to wipe the two sides of the silicon wafer for the first time to ensure that no powder falls out of the groove and there is no glass powder residue on the surface.

[0073] S5. Use the same small spoon as in step S2 to load 1.0 g of the second glass slurry. The material of the small spoon is selected as a high-temperature or corrosion-resistant material, and the spoon mouth is smooth to ensure that the glass slurry drips evenly. The ratio of the second glass slurry to the first glass slurry is different. Slowly drip it on the surface of the rotating silicon wafer. Under the action of centrifugal force, the glass slurry spreads out and is evenly smeared on the surface of the silicon wafer by a spreading tool to ensure that the glass powder evenly covers the surface of the silicon wafer. During the spreading process, the rotation speed of the rotating platform can be adjusted to improve the uniformity of the distribution of the glass slurry.

[0074] S6. Stop rotating the platform after evenly applying the glass powder slurry. Place the wafer after powder application on a high-temperature baking plate for the second drying to preliminarily cure the second layer of glass powder slurry. The temperature for the second drying is set at 180 °C, and the time for the second drying is set at 5 min. The heating method can be selected from electric heating or infrared heating;

[0075] S7. Use a special silicone rubber for manual wiping to perform the second powder wiping on both sides of the wafer to ensure that no powder drops out of the groove and there is no glass powder residue on the surface;

[0076] S8. Send the wafer after powder wiping into the furnace tube to completely cure the glass liquid to form a glass passivation layer. First, perform low-temperature curing and then high-temperature curing to finally form a high-quality glass passivation layer; the low-temperature curing temperature is set at 450 °C, the low-temperature curing time is 10 min, the high-temperature curing temperature is set at 850 °C, and the high-temperature curing time is 20 min. The heating method can be selected from resistance heating or radiation heating, and nitrogen or inert gas can be introduced to prevent oxidation.

[0077] Thus, it can be obtained from Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 that through the process design of two powder applications, two dryings, and two furnace entries, using a small spoon to load the glass powder slurry and dripping it onto the wafer surface and spreading it evenly, the uniform distribution of the glass powder slurry and a high-quality passivation layer are achieved, while meeting the process requirements of no powder dropping and no residue on the surface.

[0078] 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 the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for powdering the passivation layer of a mesa thyristor glass, characterized in that: The above powdering method specifically includes the following steps: S1. Fix the silicon wafer on the rotating platform and set the rotation speed. S2. Perform the first powdering on the silicon wafer, and then dry, wipe the powder, and send it to the furnace. S3. Perform the second powdering on the silicon wafer, and then dry, wipe the powder, and send it to the furnace.

2. The powdering method of the mesa thyristor glass passivation layer according to claim 1, characterized in that: The step S2 specifically includes the following steps: a1. Use a small spoon to load the first glass powder slurry, slowly drop it on the surface of the rotating silicon wafer, and use a spreading tool to spread the glass powder slurry on the surface of the silicon wafer. The rotation speed of the rotating platform can be adjusted during the spreading process. a2. After spreading the glass powder slurry, stop the rotating platform, place the powdered silicon wafer on a high-temperature baking plate for the first drying, so that the first glass powder slurry is initially cured to form a uniform glass liquid. a3. Perform the first powder wiping on both sides of the silicon wafer by manual powder wiping method. a4. Send the powder-wiped silicon wafer into the furnace tube for the first time to make the glass liquid completely cured.

3. The powdering method of the mesa thyristor glass passivation layer according to claim 2, characterized in that: The step S3 specifically includes the following steps: b1. Use the same small spoon as in step a1 to load the second glass powder slurry, slowly drop it on the surface of the rotating silicon wafer, and use a spreading tool to spread the glass powder slurry on the surface of the silicon wafer. The rotation speed of the rotating platform can be adjusted during the spreading process. b2. After spreading the glass powder slurry, stop the rotating platform, place the powdered silicon wafer on a high-temperature baking plate for the second drying, so that the second layer of glass powder slurry is initially cured. b3. Perform the second powder wiping on both sides of the silicon wafer by manual powder wiping method. b4. Send the powder-wiped silicon wafer into the furnace tube for the second time to make the glass liquid completely cured to form a glass passivation layer.

4. A method for powdering the passivation layer of a tabletop thyristor glass according to claim 1, characterized in that: In the step S1, the rotation speed of the rotating platform is set to 100 - 500 rpm, and the material of the rotating platform is selected from high-temperature resistant and corrosion-resistant materials.

5. The powdering method of the thyristor glass passivation layer on the table according to claim 2, characterized in that: In the step a2, the first drying temperature is set to 100 - 300 °C, and the first drying time is set to 3 - 10 min.

6. The powdering method for the mesa thyristor glass passivation layer according to claim 3, characterized in that: In the step b2, the second drying temperature is set to 100 - 300 °C, and the second drying time is set to 3 - 10 min.

7. A method for powdering the thyristor glass passivation layer of a tabletop, according to claim 2, characterized in that: In the step a4, when sending into the furnace tube for the first time, first perform low-temperature curing and then high-temperature curing. The low-temperature curing temperature is set to 300 - 500 °C, the low-temperature curing time is 10 - 20 min, the high-temperature curing temperature is set to 600 - 900 °C, and the high-temperature curing time is 20 - 30 min.

8. A method for powdering the thyristor glass passivation layer of a tabletop according to claim 3, characterized in that: In the step b4, when sending into the furnace tube for the second time, first perform low-temperature curing and then high-temperature curing. The low-temperature curing temperature is set to 300 - 500 °C, the low-temperature curing time is 10 - 20 min, the high-temperature curing temperature is set to 600 - 900 °C, and the high-temperature curing time is 20 - 30 min.

9. A method for powdering a mesa thyristor glass passivation layer according to claim 2, characterized in that: In the step a1, the material of the small spoon is selected from stainless steel or ceramic materials.

10. A method for powdering the silicon-controlled glass passivation layer of a tabletop according to claim 3, characterized in that: The rotating platform, small spoon, high-temperature baking plate, and furnace tube are all controlled to operate through a connected automated control system.