A method of polishing a semiconductor material wafer

Abstract

This invention relates to the field of polishing technology and discloses a method for polishing semiconductor material wafers, comprising the following steps: Step 1) processing including preparation, detection, filtration, and heating; Step 4) immersion polishing; Step 5) spray polishing; Step 6) cleaning and drying; and Step 7) recycling of the polishing slurry. This method for polishing semiconductor material wafers improves the polishing effect and condition of the semiconductor material wafer by treating and detecting the polishing slurry before polishing, including filtration and heating. The polishing slurry is kept in a good state before polishing the semiconductor material wafer, resulting in a better polishing effect after polishing both sides. Furthermore, the drying process of the semiconductor material wafer and the recycling of the polishing slurry further improve the polishing effect, quality, and convenience of the semiconductor material wafer polishing process.

Description

Technical Field

[0001] This invention relates to the field of polishing technology, specifically to a polishing method for semiconductor material wafers. Background Technology

[0002] For electronics, microelectronics, and microelectromechanical systems, semiconductor material wafers with extreme requirements for overall and local flatness (nanotope), roughness (surface gloss), and purity (free from foreign atoms, especially metals) are needed as starting materials (substrates). Semiconductor materials are compound semiconductors such as gallium arsenide, or elemental semiconductors such as silicon, sometimes germanium, or their layered structures.

[0003] Semiconductor wafers are produced in multiple processing steps, starting with crystal pulling, followed by crystal cutting into wafers, and finally surface preparation. Surface preparation aims to achieve a defect-free, highly flat (planar) semiconductor wafer surface. In this case, polishing is a surface preparation method. Various methods for polishing semiconductor wafers are known in the prior art, including single-sided polishing and double-sided polishing.

[0004] Currently, the polishing process in semiconductor wafer processing focuses on material inspection and double-sided polishing, but the treatment of the polishing slurry before polishing is neglected. Only when the polishing slurry is treated to maximize its effectiveness can the polishing effect of semiconductor wafers be improved. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the shortcomings of existing technologies, this invention provides a polishing method for semiconductor material wafers, which has the advantage of improving polishing effect. It solves the problem that current polishing processes for semiconductor material wafers focus on material inspection and double-sided polishing, but neglect the treatment of polishing slurry before polishing. Only when the polishing slurry is treated to maximize its function can the polishing effect of semiconductor material wafers be improved.

[0007] (II) Technical Solution

[0008] To achieve the aforementioned goal of improving polishing results, the present invention provides the following technical solution: a polishing method for semiconductor material wafers, comprising the following steps:

[0009] Step 1) Treating the polishing slurry: Before processing semiconductor wafers, a suitable polishing slurry is selected and treated. The treatment includes preparation, testing, filtration and heating processes to ensure the polishing effect on the semiconductor wafers.

[0010] Step 2) The preparation and testing in Step 1) includes diluting and stirring the concentrated polishing liquid evenly, then sampling and testing the pH value of the diluted polishing liquid, as well as testing the viscosity of the polishing liquid, the harmful substance detection index of the polishing liquid, and other detection indexes of the polishing liquid.

[0011] Step 3) The filtration and heating in Step 1) includes heating the qualified polishing liquid in a container, stirring with a stirring rod until the polishing liquid is heated to 30-55 degrees Celsius, and then filtering the polishing liquid to remove the precipitates and set it aside for later use; this avoids metal objects falling into the polishing liquid, which would cause waste and failure of the polishing liquid.

[0012] Step 4) Clamp the semiconductor material wafer and immerse it in the adjusted polishing solution. During immersion, slowly rotate the position of the semiconductor material wafer as needed to ensure more uniform immersion for 20-200 seconds to pre-polish the semiconductor material wafer. After immersion, remove and set aside.

[0013] Step 5) Clamp the semiconductor material wafer and then use a high-pressure water gun to rinse the semiconductor material wafer with polishing liquid under high pressure to achieve the effect of polishing the semiconductor material wafer again. Maintain vibration during polishing. After polishing the top, flip the semiconductor material wafer over and spray and polish the other side. Spray and polish multiple sides of the semiconductor material wafer to improve the smoothness of the semiconductor material wafer.

[0014] Step 6) Cleaning: After polishing, place the semiconductor material wafer inside the ultrasonic container for cleaning for 8-15 minutes, and finally dry it in a nitrogen atmosphere.

[0015] Step 7) Polishing fluid recycling: Collect the polishing fluid during polishing using a container and recycle it to achieve effective recycling, save costs, and reduce pollution.

[0016] Preferably, the inspection of the appearance of the polishing liquid in step 1) also includes the inspection of the polishing liquid viscosity, the inspection of harmful substances in the polishing liquid, and other inspection indicators of the polishing liquid. During the inspection, the appearance of the polishing liquid is checked to see if it is a yellow viscous liquid, which is done by visual inspection. The viscosity of the polishing liquid is generally between 500 and 100 cps. The harmful substances in the polishing liquid include: total bacterial count, coliform bacteria, pathogenic bacteria, heavy metals, and arsenic. Other inspection indicators of the polishing liquid include: particle size distribution, solid content, density, dilution ratio, and environmental performance.

[0017] Preferably, the polishing fluid includes diamond polishing fluid and silicon oxide polishing fluid.

[0018] Preferably, the pH value of the polishing fluid is between 4 and 8.

[0019] (III) Beneficial Effects

[0020] Compared with the prior art, the present invention provides a polishing method for semiconductor material wafers, which has the following beneficial effects:

[0021] The polishing method for semiconductor wafers involves treating and testing the polishing slurry before polishing, including filtering and heating, to maintain the slurry in a good state before polishing the semiconductor wafer. This improves the polishing effect and condition of the semiconductor wafer. After polishing both sides, a better polishing effect is achieved. Furthermore, drying the semiconductor wafer and recycling the polishing slurry during polishing further enhance the polishing effect, quality, and ease of use. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A polishing method for semiconductor material wafers, comprising the following steps:

[0024] Step 1) Processing the polishing slurry. The polishing slurry includes diamond polishing slurry and silicon oxide polishing slurry. First, before processing semiconductor material wafers, a suitable polishing slurry is selected and processed. The processing includes preparation, testing, filtration and heating processes to ensure the polishing effect on semiconductor material wafers.

[0025] Step 2) The preparation and testing in Step 1) includes diluting and stirring the concentrated polishing liquid evenly, then sampling and testing the pH value of the diluted polishing liquid. The pH value of the polishing liquid is 4. The appearance of the polishing liquid is tested. The appearance should be a yellow viscous liquid. It also includes testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indexes of the polishing liquid. The appearance of the polishing liquid in Step 2) includes testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indexes of the polishing liquid. During the testing, the appearance of the polishing liquid is tested to see if it is a yellow viscous liquid. This is done by visual inspection. The viscosity of the polishing liquid is generally 500 cps. The detection index of harmful substances in the polishing liquid includes: total bacterial count, coliform bacteria, pathogenic bacteria, heavy metals, arsenic. Other detection indexes of the polishing liquid include: particle size distribution, solid content, density, dilution ratio, and environmental performance.

[0026] Step 3) The filtration and heating in Step 1) includes heating the qualified polishing liquid in a container, stirring with a stirring rod until the polishing liquid reaches 30 degrees Celsius, and then filtering the polishing liquid to remove the precipitates and set it aside for later use; this avoids metal objects falling into the polishing liquid, which would cause waste and failure of the polishing liquid.

[0027] Step 4) Clamp the semiconductor material wafer and immerse it in the adjusted polishing solution. During immersion, slowly rotate the position of the semiconductor material wafer as needed to ensure more uniform immersion for 20 seconds to pre-polish the semiconductor material wafer. After immersion, remove and set aside.

[0028] Step 5) Clamp the semiconductor material wafer and then use a high-pressure water gun to rinse the semiconductor material wafer with polishing liquid under high pressure to achieve the effect of polishing the semiconductor material wafer again. Maintain vibration during polishing. After polishing the top, flip the semiconductor material wafer over and spray and polish the other side. Spray and polish multiple sides of the semiconductor material wafer to improve the smoothness of the semiconductor material wafer.

[0029] Step 6) Cleaning: After polishing, place the semiconductor material wafer inside the ultrasonic container for cleaning for 8-15 minutes, and finally dry it in a nitrogen atmosphere.

[0030] Step 7) Polishing fluid recycling: Collect the polishing fluid during polishing using a container and recycle it to achieve effective recycling, save costs, and reduce pollution.

[0031] Example 2: A polishing method for semiconductor material wafers, comprising the following steps:

[0032] Step 1) Processing the polishing slurry. The polishing slurry includes diamond polishing slurry and silicon oxide polishing slurry. First, before processing semiconductor material wafers, a suitable polishing slurry is selected and processed. The processing includes preparation, testing, filtration and heating processes to ensure the polishing effect on semiconductor material wafers.

[0033] Step 2) The preparation and testing in Step 1) includes diluting and stirring the concentrated polishing liquid evenly, then sampling and testing the pH value of the diluted polishing liquid. The pH value of the polishing liquid should be between 6 and 6. The appearance of the polishing liquid is also tested. It should remain a yellow, viscous liquid. This also includes testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indicators of the polishing liquid. In Step 2), the appearance of the polishing liquid is tested, including testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indicators of the polishing liquid. During the testing, the appearance of the polishing liquid is checked to see if it is a yellow, viscous liquid. This is done by visual inspection. The viscosity of the polishing liquid is generally around 800 cps. The detection index of harmful substances in the polishing liquid includes: total bacterial count, coliform bacteria, pathogenic bacteria, heavy metals, and arsenic. Other detection indicators of the polishing liquid include: particle size distribution, solid content, density, dilution ratio, and environmental performance.

[0034] Step 3) The filtration and heating in Step 1) includes heating the qualified polishing liquid in a container, stirring with a stirring rod until the polishing liquid reaches 48 degrees Celsius, and filtering the polishing liquid after stirring evenly to remove the precipitates in the polishing liquid and keeping it for later use; to avoid metal objects falling into the polishing liquid, which would cause waste and failure of the polishing liquid.

[0035] Step 4) Clamp the semiconductor material wafer and immerse it in the adjusted polishing solution. During immersion, slowly rotate the position of the semiconductor material wafer as needed to ensure more uniform immersion. Perform pre-polishing treatment on the semiconductor material wafer for 100 seconds. After immersion, remove and set aside.

[0036] Step 5) Clamp the semiconductor material wafer and then use a high-pressure water gun to rinse the semiconductor material wafer with polishing liquid under high pressure to achieve the effect of polishing the semiconductor material wafer again. Maintain vibration during polishing. After polishing the top, flip the semiconductor material wafer over and spray and polish the other side. Spray and polish multiple sides of the semiconductor material wafer to improve the smoothness of the semiconductor material wafer.

[0037] Step 6) Cleaning: After polishing, place the semiconductor material wafer inside the ultrasonic container for cleaning for 8-15 minutes, and finally dry it in a nitrogen atmosphere.

[0038] Step 7) Polishing fluid recycling: Collect the polishing fluid during polishing using a container and recycle it to achieve effective recycling, save costs, and reduce pollution.

[0039] Example 3: A polishing method for semiconductor material wafers, comprising the following steps:

[0040] Step 1) Processing the polishing slurry. The polishing slurry includes diamond polishing slurry and silicon oxide polishing slurry. First, before processing semiconductor material wafers, a suitable polishing slurry is selected and processed. The processing includes preparation, testing, filtration and heating processes to ensure the polishing effect on semiconductor material wafers.

[0041] Step 2) The preparation and testing in Step 1) includes diluting and stirring the concentrated polishing liquid evenly, then sampling and testing the pH value of the diluted polishing liquid. The pH value of the polishing liquid is 8. The appearance of the polishing liquid is also tested. It should remain a yellow, viscous liquid. This also includes testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indicators of the polishing liquid. In Step 2), the appearance of the polishing liquid is tested, including testing the viscosity of the polishing liquid, the detection index of harmful substances in the polishing liquid, and other detection indicators of the polishing liquid. During the testing, the appearance of the polishing liquid is checked to see if it is a yellow, viscous liquid. This is done by visual inspection. The viscosity of the polishing liquid is generally 100 cps. The detection index of harmful substances in the polishing liquid includes: total bacterial count, coliform bacteria, pathogenic bacteria, heavy metals, and arsenic. Other detection indicators of the polishing liquid include: particle size distribution, solid content, density, dilution ratio, and environmental performance.

[0042] Step 3) The filtration and heating in Step 1) includes heating the qualified polishing liquid in a container, stirring with a stirring rod until the polishing liquid reaches 55 degrees Celsius, and filtering the polishing liquid after stirring evenly to remove the precipitates in the polishing liquid and keeping it for later use; to avoid metal objects falling into the polishing liquid, which would cause waste and failure of the polishing liquid.

[0043] Step 4) Clamp the semiconductor material wafer and immerse it in the adjusted polishing solution. During immersion, slowly rotate the position of the semiconductor material wafer as needed to ensure more uniform immersion for 200 seconds to pre-polish the semiconductor material wafer. After immersion, remove and set aside.

[0044] Step 5) Clamp the semiconductor material wafer and then use a high-pressure water gun to rinse the semiconductor material wafer with polishing liquid under high pressure to achieve the effect of polishing the semiconductor material wafer again. Maintain vibration during polishing. After polishing the top, flip the semiconductor material wafer over and spray and polish the other side. Spray and polish multiple sides of the semiconductor material wafer to improve the smoothness of the semiconductor material wafer.

[0045] Step 6) Cleaning: After polishing, place the semiconductor material wafer inside the ultrasonic container for cleaning for 8-15 minutes, and finally dry it in a nitrogen atmosphere.

[0046] Step 7) Polishing fluid recycling: Collect the polishing fluid during polishing using a container and recycle it to achieve effective recycling, save costs, and reduce pollution.

[0047] Judgment criteria: The three experimental cases were tested in turn, and the experimental case with the better polishing effect was used as the standard.

[0048] The beneficial effects of this invention are as follows: the polishing method for semiconductor material wafers, by treating and testing the polishing slurry before polishing the semiconductor material wafer, including filtering and heating, keeps the polishing slurry in a good state, thereby improving the polishing effect and state of the semiconductor material wafer. Then, after polishing both sides, a better polishing effect is achieved. Furthermore, the drying treatment of the semiconductor material wafer and the recycling treatment of the polishing slurry during polishing further improve the polishing effect, quality, and convenience of the semiconductor material wafer.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of polishing a semiconductor material wafer, characterized by, Includes the following steps: Step 1) Treating the polishing slurry: Before processing semiconductor wafers, a suitable polishing slurry is selected and treated. The treatment includes preparation, testing, filtration and heating processes to ensure the polishing effect on the semiconductor wafers. Step 2) The preparation and testing in Step 1) includes diluting and stirring the concentrated polishing liquid evenly, then sampling and testing the pH value of the diluted polishing liquid, testing the appearance of the polishing liquid (it should be a yellow viscous liquid), and also testing the viscosity of the polishing liquid, the harmful substance detection index of the polishing liquid, and other detection indexes of the polishing liquid. Step 3) The filtration and heating in Step 1) includes heating the qualified polishing liquid in a container, stirring with a stirring rod until the polishing liquid is heated to 30-55 degrees Celsius, and then filtering the polishing liquid to remove the precipitates and set it aside for later use; this avoids metal objects falling into the polishing liquid, which would cause waste and failure of the polishing liquid. Step 4) Clamp the semiconductor material wafer and immerse it in the adjusted polishing solution. During immersion, slowly rotate the position of the semiconductor material wafer as needed to ensure more uniform immersion for 20-200 seconds to pre-polish the semiconductor material wafer. After immersion, remove and set aside. Step 5) Clamp the semiconductor material wafer and then use a high-pressure water gun to rinse the semiconductor material wafer with polishing liquid under high pressure to achieve the effect of polishing the semiconductor material wafer again. Maintain vibration during polishing. After polishing the top, flip the semiconductor material wafer over and spray and polish the other side. Spray and polish multiple sides of the semiconductor material wafer to improve the smoothness of the semiconductor material wafer. Step 6) Cleaning: After polishing, place the semiconductor material wafer inside the ultrasonic container for cleaning for 8-15 minutes, and finally dry it in a nitrogen atmosphere. Step 7) Polishing fluid recycling: Collect the polishing fluid during polishing using a container and recycle it to achieve effective recycling, save costs, and reduce pollution.

2. The method of claim 1 wherein the polishing pad is a fixed abrasive pad. The appearance test of the polishing liquid in step 2) also includes the testing of the polishing liquid viscosity, the testing of harmful substances in the polishing liquid, and other testing indicators of the polishing liquid. During the test, the appearance of the polishing liquid is checked to see if it is a yellow viscous liquid, which is done by visual inspection. The viscosity of the polishing liquid is generally between 500 and 100 cps. The testing indicators of harmful substances in the polishing liquid include: total bacterial count, coliform bacteria, pathogenic bacteria, heavy metals, and arsenic. Other testing indicators of the polishing liquid include: particle size distribution, solid content, density, dilution ratio, and environmental performance.

3. The polishing method for a semiconductor material wafer according to claim 1, characterized in that, The polishing fluid includes diamond polishing fluid and silicon dioxide polishing fluid.

4. The polishing method for a semiconductor material wafer according to claim 1, characterized in that, The pH value of the polishing solution is between 4 and 8.