Method for determining double-sided grinding removal rate of silicon carbide wafer

Abstract

The invention provides a method for determining the double-sided grinding removal rate of a silicon carbide wafer, and belongs to the technical field of wafer machining, marks are machined on the carbon surface and the silicon surface of the wafer respectively, the marks are a plurality of grooves, and the groove depths of the grooves are changed in a gradient mode; after the marking processing is completed, respectively photographing the carbon surface and the silicon surface of the wafer; carrying out double-sided grinding on the wafer; after the double-sided grinding is completed, respectively photographing the carbon surface and the silicon surface of the wafer; the removal amount of the carbon surface and the removal amount of the silicon surface can be obtained by comparing the marks before and after the carbon surface is processed and comparing the marks before and after the silicon surface is processed; the removal rate of the carbon surface can be obtained by dividing the removal amount of the carbon surface by the grinding time, and the removal rate of the silicon surface can be obtained by dividing the removal amount of the silicon surface by the grinding time; the confirmation process of the thickness removal amount of the carbon surface and the silicon surface is rapid and visual, a large amount of additional complex calculation is not needed, and errors can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer processing, and in particular relates to a method for determining a double-sided grinding removal rate of a silicon carbide wafer. Background Art

[0002] At present, during the double-sided grinding process of silicon carbide wafers, the upper and lower surfaces of silicon carbide are processed and removed at the same time; the removal thickness displayed in the double-sided grinding equipment is the sum of the carbon surface thickness and the silicon surface thickness. Therefore, during the double-sided grinding process, it is impossible to determine the removal amount of the carbon surface and the silicon surface respectively.

[0003] In the prior art, when determining the carbon surface removal rate and the silicon surface removal rate respectively, the silicon carbide wafer is first epitaxially grown to form an epitaxial layer; then the thickness of the silicon carbide wafer and the epitaxial layer as a whole is measured; after double-sided grinding, the thickness of the silicon carbide wafer and the epitaxial layer as a whole is measured again; the difference measured before and after grinding can be used to calculate the removal amount of the silicon surface and the carbon surface respectively during the double-sided grinding process, and then divided by the grinding time to obtain the grinding efficiency of the carbon surface and the silicon surface.

[0004] However, the above-mentioned method of determining the removal rate is prone to errors because the removal amounts of the carbon surface and the silicon surface are obtained through calculation. Summary of the invention

[0005] The embodiment of the present invention provides a method for determining the removal rate of double-sided grinding of a silicon carbide wafer, aiming to solve the problem that the removal rate method in the prior art is prone to errors.

[0006] To achieve the above object, the technical solution adopted by the present invention is: A method for determining a removal rate of double-sided grinding of a silicon carbide wafer is provided, comprising the following steps: Marks are processed on the carbon surface and the silicon surface of the wafer respectively, the marks are multiple grooves, and the groove depths of the multiple grooves vary in a gradient manner; After the marking process is completed, the carbon side and silicon side of the wafer are photographed respectively; and the wafer is double-sided polished; After double-sided grinding is completed, the carbon side and silicon side of the wafer are photographed separately; By comparing the marks before and after the carbon surface processing, and comparing the marks before and after the silicon surface processing, the removal amount of the carbon surface and the removal amount of the silicon surface can be obtained; The amount of carbon surface removed divided by the grinding time can be used to obtain the carbon surface removal rate, and the amount of silicon surface removed divided by the grinding time can be used to obtain the silicon surface removal rate.

[0007] In a possible implementation, a positioning surface is provided on the wafer, and after photographs are taken of the carbon surface and the silicon surface of the wafer, the depth of the mark is marked on the photographs.

[0008] In a possible implementation, the width of the mark is 0.1 mm to 0.2 mm, and the depth of the mark is greater than or equal to 1 μm.

[0009] In a possible implementation manner, the mark is in a ring shape or a strip shape.

[0010] In a possible implementation, when the shape of the mark is ring-shaped, the distribution interval of the mark is 0.01 to 0.1 times the diameter, and gradually expands from the center to the outside.

[0011] In a possible implementation, when the mark is in the shape of a strip, the mark passes through the center point of the wafer, and the mark is evenly distributed on the wafer.

[0012] In a possible implementation, the marks are grooves parallel to each other, or the marks are radial grooves.

[0013] In a possible implementation, the gradient variation of the marked groove depth is 1 μm.

[0014] In a possible implementation, after the double-side grinding of the wafer, the wafer is rinsed and then blown dry.

[0015] In a possible implementation, a precision engraving machine is used to process marks on the carbon surface and the silicon surface of the wafer respectively, and a scanner is used to photograph and scan the carbon surface and the silicon surface of the wafer.

[0016] The present invention provides a method for determining the double-sided grinding removal rate of a silicon carbide wafer. Compared with the prior art, the method confirms the removal amounts of the carbon surface and the silicon surface by machining marks of different depths on the wafer surface, and compares the changes of the marks before and after machining, thereby obtaining the removal rates of the upper and lower surfaces. The present invention is simple and safe to operate, and does not require high-temperature treatment of the substrate. The process of confirming the thickness removal amounts of the carbon surface and the silicon surface is fast and intuitive, and does not require a large number of additional complex calculations, thereby reducing errors. The present invention solves the problem that the removal rates of the upper and lower surfaces cannot be determined during the double-sided machining process, and provides a basis for accurately and efficiently optimizing parameters in the double-sided machining of silicon carbide in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention; Figure 2 A schematic diagram of a silicon carbide wafer for a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention; Figure 3 A schematic diagram of Example 1 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention before processing; Figure 4 A schematic diagram of Example 1 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention after processing; Figure 5 A schematic diagram of Example 2 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention before processing; Figure 6 A schematic diagram of Example 2 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention after processing; Figure 7 A schematic diagram of Example 3 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention before processing; Figure 8 A schematic diagram of Example 3 of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention after processing; Fig. 9 A schematic diagram of a method for determining a removal rate of double-sided grinding of a silicon carbide wafer provided by an embodiment of the present invention, wherein the marking shape is a ring.

[0018] Description of the accompanying drawings: 1. Positioning surface. DETAILED DESCRIPTION

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Please also read Figures 1 to 9 Now, a method for determining the removal rate of double-sided grinding of silicon carbide wafers provided by the present invention is described. The method for determining the removal rate of double-sided grinding of silicon carbide wafers comprises the following steps: Marks are processed on the carbon surface and silicon surface of the wafer respectively, and the marks are multiple grooves, and the groove depths of the multiple grooves vary in gradient; after the marking process is completed, the carbon surface and silicon surface of the wafer are photographed respectively; and the wafer is double-sided ground; after the double-sided grinding is completed, the carbon surface and silicon surface of the wafer are photographed respectively; by comparing the marks before and after the carbon surface processing, and comparing the marks before and after the silicon surface processing, the removal amount of the carbon surface and the removal amount of the silicon surface can be obtained; the removal amount of the carbon surface divided by the grinding time can obtain the removal rate of the carbon surface, and the removal amount of the silicon surface divided by the grinding time can obtain the removal rate of the silicon surface.

[0021] The present invention provides a method for determining the double-sided grinding removal rate of a silicon carbide wafer. Compared with the prior art, the method confirms the removal amounts of the carbon surface and the silicon surface by machining marks of different depths on the wafer surface, and compares the changes of the marks before and after machining, thereby obtaining the removal rates of the upper and lower surfaces. The present invention is simple and safe to operate, and does not require high-temperature treatment of the substrate. The process of confirming the thickness removal amounts of the carbon surface and the silicon surface is fast and intuitive, and does not require a large number of additional complex calculations, thereby reducing errors. The present invention solves the problem that the removal rates of the upper and lower surfaces cannot be determined during the double-sided machining process, and provides a basis for accurately and efficiently optimizing parameters in the double-sided machining of silicon carbide in actual production.

[0022] It should be noted that a precision engraving machine is used to process marks on the carbon surface and silicon surface of the wafer respectively, and the carbon surface and silicon surface of the wafer are photographed and scanned by a scanner; after the double-sided grinding of the wafer, the wafer is rinsed, and then the wafer is blown dry. After the wafer is blown dry, the carbon surface and silicon surface of the wafer are photographed and scanned again by a scanner. There is a positioning surface 1 on the wafer. After taking pictures of the carbon surface and silicon surface of the wafer, the depth of the mark is indicated on the photo. Through the positioning surface 1 on the wafer, the corresponding relationship between the mark after the wafer is ground and the mark before the grinding can be known, which is convenient for determining the removal amount.

[0023] Exemplarily, the width of the mark is 0.1 mm to 0.2 mm, the depth of the mark is greater than or equal to 1 μm, and the gradient variation of the groove depth of the mark is 1 μm.

[0024] Exemplarily, the shape of the mark is ring-shaped or strip-shaped. When the shape of the mark is ring-shaped, the distribution spacing of the mark is 0.01 to 0.1 times the diameter, and gradually expands from the center to the outside; the shape of the mark can also be arc-shaped.

[0025] Exemplarily, when the mark is in the form of a strip, the mark passes through the center point of the wafer, and the marks are evenly distributed on the wafer, the marks are parallel to each other, or the marks are radial grooves.

[0026] In addition, the mark is not limited to the above-mentioned shape, and the mark may be any other shape.

[0027] Embodiment 1: Step 1: Select 5 silicon carbide wafers with a thickness of 600±5μm and a diameter of 200mm, select one of the silicon carbide wafers, and mark it on its carbon surface and silicon surface respectively. The marking width is 0.1mm, and the depth is 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm (such as Figure 3 as shown).

[0028] Step 2: Use a scanner to take a photo and scan the marked substrate.

[0029] Step 3: Use boron carbide polishing fluid at a pressure of 90kgf / cm 2 After the processing is completed, the silicon carbide wafer is removed, rinsed with pure water for 5 minutes, and dried with a hair dryer.

[0030] Step 4: Scan and take photos of the dried silicon carbide wafer under a scanner to check the mark changes (such as Figure 4 as shown).

[0031] Step 5: Compare the changes in the marks before and after processing. The marks within 11μm on the carbon surface are invisible, and the marks within 7μm on the silicon surface are invisible. It can be concluded that the carbon surface removal amount is 10μm, the silicon surface removal amount is 6μm, and the carbon surface removal rate ν=10 / 30=0.33μm·min -1 , silicon surface removal rate ν = 6 / 30 = 0.20 μm·min -1 Embodiment 2: Step 1: Select 5 silicon carbide wafers with a thickness of 500±5μm and a diameter of 150mm, select one of the silicon carbide wafers, and mark it on its carbon surface and silicon surface respectively. The marking width is 0.2mm, and the depth distribution gradually increases from the center to the outside. The depths of area 1 are 20μm, 21μm, 22μm, ..., 29μm, the depths of area 2 are 30μm, 31μm, 32μm, ..., 39μm, and the depths of area 3 are 40μm, 41μm, 42μm, ..., 49μm; area 4 is the same as area 1, area 5 is the same as area 2, and area 6 is the same as area 3 (such as Figure 5 as shown).

[0032] Step 2: Use a scanner to take a photo and scan the marked substrate.

[0033] Step 3: Use boron carbide polishing fluid at a pressure of 160kgf / cm 2 The processing was carried out for 90 minutes. After the processing was completed, the silicon carbide wafer was removed, rinsed with pure water for 5 minutes, and dried with a hair dryer.

[0034] Step 4: Scan and take photos of the dried silicon carbide wafer under a scanner to check the mark changes (such as Figure 6 as shown).

[0035] Step 5: Comparing the changes in marks before and after processing, the marks in area 1 and area 2 on the carbon surface are invisible, and the minimum depth is 44μm. The mark in area 1 on the silicon surface is invisible, and the minimum depth is 38μm. It can be concluded that the carbon surface removal amount is 43μm, the silicon surface removal amount is 37μm, and the carbon surface removal rate ν=43 / 90=0.48μm·min -1 , silicon surface removal rate ν = 37 / 90 = 0.41 μm min-1 .

[0036] Embodiment 3: Step 1: Select 20 silicon carbide wafers with a thickness of 400±5μm and a diameter of 100mm, and select one of them to mark on its carbon surface and silicon surface respectively. The marking is 0.15mm wide and the depth distribution is 5μm~23μm (such as Figure 7 as shown).

[0037] Step 2: Use a scanner to take a photo and scan the marked substrate.

[0038] Step 3: Use boron carbide polishing fluid at a pressure of 150kgf / cm 2 The processing was carried out for 100 minutes. After the processing was completed, the silicon carbide wafer was removed, rinsed with pure water for 5 minutes, and dried with a hair dryer.

[0039] Step 4: Scan and take photos of the dried silicon carbide wafer under a scanner to check the mark changes (such as Figure 8 as shown).

[0040] Step 5: Compare the changes in the marks before and after processing. The marks within 19μm on the carbon surface are invisible, and the marks within 13μm on the silicon surface are invisible. It can be concluded that the carbon surface removal amount is 18μm, the silicon surface removal amount is 12μm, and the carbon surface removal rate ν=18 / 100=0.18μm·min -1 , silicon surface removal rate ν = 12 / 100 = 0.12 μm·min -1。

[0041] It should be noted that Figure 7 and Figure 8 The dashed lines in the figure are auxiliary lines drawn on the photo. The dashed lines will not be processed on the wafer.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the removal rate of double-sided grinding of silicon carbide wafers, characterized in that: The following steps are involved: Marks are processed on the carbon surface and the silicon surface of the wafer respectively, the marks are multiple grooves, and the groove depths of the multiple grooves vary in a gradient manner; After the marking process is completed, the carbon side and silicon side of the wafer are photographed separately; And double-sided grinding of the wafer; After double-sided grinding is completed, the carbon side and silicon side of the wafer are photographed separately; By comparing the marks before and after the carbon surface processing, and comparing the marks before and after the silicon surface processing, the removal amount of the carbon surface and the removal amount of the silicon surface can be obtained; The amount of carbon surface removed divided by the grinding time can be used to obtain the carbon surface removal rate, and the amount of silicon surface removed divided by the grinding time can be used to obtain the silicon surface removal rate.

2. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to claim 1, characterized in that: The wafer has a positioning surface, and after taking pictures of the carbon side and the silicon side of the wafer, the depth of the mark is marked on the picture.

3. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to claim 1, characterized in that: The width of the mark is 0.1 mm to 0.2 mm, and the depth of the mark is greater than or equal to 1 μm.

4. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to claim 1, characterized in that: The shape of the mark is ring-shaped or strip-shaped.

5. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer as claimed in claim 4, characterized in that: When the shape of the mark is ring-shaped, the distribution spacing of the mark is 0.01~0.1 times the diameter, gradually expanding from the center to the outside.

6. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer as claimed in claim 4, characterized in that: When the marking is in the form of a strip, the marking passes through the center point of the wafer and the marking is evenly distributed on the wafer.

7. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to claim 6, characterized in that: The grooves are marked as parallel to each other, or the grooves are marked as radial.

8. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to any one of claims 1 to 7, characterized in that: The gradient variation of the groove depth is 1 μm.

9. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to any one of claims 1 to 7, characterized in that: After double-sided grinding of the wafer, the wafer is rinsed and then blown dry.

10. A method for determining a removal rate of double-sided grinding of a silicon carbide wafer according to any one of claims 1 to 7, characterized in that: A precision engraving machine is used to process marks on the carbon surface and silicon surface of the wafer respectively, and a scanner is used to photograph and scan the carbon surface and silicon surface of the wafer.

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