A system and method for detecting the depth of a peripheral damage layer of a silicon wafer

Abstract

The embodiment of the present application discloses a system and method for detecting the depth of the peripheral damage layer of a silicon wafer, the system comprising: a cross-section acquisition device for acquiring the cross-section of the silicon wafer, wherein the cross-section is perpendicular to the silicon wafer; a measuring device for measuring the diameter of the silicon wafer and measuring the cross-sectional size of the cross-section in a first direction parallel to the silicon wafer; a size acquisition device for acquiring the damage layer size of the peripheral damage layer in the cross-section and in the first direction; and a calculation device for calculating the depth of the peripheral damage layer according to the diameter, the cross-sectional size and the damage layer size.

Description

Technical Field

[0001] This invention relates to the field of semiconductor silicon wafer manufacturing, and more particularly to a system and method for detecting the depth of peripheral damage layers on silicon wafers. Background Technology

[0002] During silicon wafer manufacturing, machining processes such as tumbling, cutting, grinding, and polishing inevitably introduce mechanical damage to the main surface and side surfaces of the silicon wafer, forming a main surface damage layer and a peripheral damage layer. This mechanical damage disrupts the original monocrystalline layer, and if not removed promptly, it will affect the quality of products produced by subsequent processing. Therefore, it is necessary to accurately measure the depth of the mechanical damage layer to determine parameters such as the amount of material removed during subsequent processes.

[0003] It is known that the depth of this type of mechanical damage is relatively small, making it difficult to accurately detect its specific depth using existing equipment. Currently, for the main surface damage layer of silicon wafers, methods such as "angle polishing" are often used for detection. In this angle polishing method, the silicon wafer is first split into multiple pieces as measurement samples. Then, the measurement samples are angle polished at an angle to form a bevel. The bevel is then etched using an etching solution so that defects in the main surface damage layer of the silicon wafer can be better displayed on the bevel. Here, angle polishing acts as an "amplifier" for the damage layer. That is, by measuring the length of the damage layer on the bevel using a microscope and multiplying it by the sine of the polishing angle, the depth of the damage layer can be obtained.

[0004] However, the aforementioned "angle polishing method" requires first splitting the silicon wafer into multiple small samples before subsequent testing. Furthermore, the small size of the split samples makes them incompatible with standard etching machines, necessitating the use of auxiliary tools such as special fixtures or glove boxes during etching, which is inconvenient. Additionally, measuring the damage depth at multiple locations along the wafer edge requires repeatedly performing the vertical, polishing, and etching operations on multiple samples, resulting in a long overall measurement time. While the "angle polishing method" can also be used to detect peripheral damage layers on the silicon wafer, the aforementioned problems also apply when measuring the thickness of the peripheral damage layer. Moreover, since the peripheral damage layer is perpendicular to the main surface damage layer, the required testing surfaces are also perpendicular. Therefore, the testing surfaces obtained using the polishing device of the main surface damage layer detection system are unsuitable for detecting peripheral damage layers. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention aims to provide a system and method for detecting the depth of a peripheral damage layer on a silicon wafer, which can avoid the various problems caused by the aforementioned "angle polishing method" and obtain the detection surface required for detecting the depth of the peripheral damage layer.

[0006] The technical solution of this invention is implemented as follows:

[0007] In a first aspect, the present invention provides a system for detecting the depth of a peripheral damage layer on a silicon wafer, the system comprising:

[0008] A cross-section obtaining device is used to obtain a cross-section of the silicon wafer, wherein the cross-section is perpendicular to the silicon wafer;

[0009] A measuring device for measuring the diameter of the silicon wafer and the cross-sectional dimensions of the cross section in a first direction parallel to the silicon wafer;

[0010] A size acquisition device, the size acquisition device being used to acquire the size of the peripheral damage layer in the cross section and in the first direction;

[0011] A computing device for calculating the depth of the peripheral damage layer based on the diameter, the cross-sectional dimensions, and the damage layer dimensions.

[0012] Secondly, embodiments of the present invention provide a method for detecting the depth of a peripheral damage layer on a silicon wafer, the method comprising:

[0013] Obtain a cross-section of the silicon wafer, wherein the cross-section is perpendicular to the silicon wafer;

[0014] Measure the diameter of the silicon wafer and measure the cross-sectional dimensions of the cross section in a first direction parallel to the silicon wafer;

[0015] Obtain the size of the peripheral damage layer in the cross section and in the first direction;

[0016] The depth of the peripheral damage layer is calculated based on the diameter, the cross-sectional dimensions, and the damage layer dimensions.

[0017] This invention provides a system and method for detecting the depth of peripheral damage layers on silicon wafers. Compared with the "angle polishing method", it can obtain a cross-section on the basis of an intact silicon wafer without splitting the wafer, reducing the process steps in the detection process. In addition, since the silicon wafer can remain intact, it is compatible with standard etching machines, thereby simplifying the operation. Finally, the position of the cross-section in the silicon wafer can be selected as needed, avoiding the situation where the obtained detection surface is only suitable for detecting the thickness of the damage layer on the main surface. Attached Figure Description

[0018] Figure 1 A schematic diagram of a system for detecting the depth of a peripheral damage layer on a silicon wafer, according to an embodiment of the present invention, is shown in conjunction with a front view of the silicon wafer.

[0019] Figure 2 An illustrative schematic diagram illustrating the calculation method employed by a computing device according to an embodiment of the present invention;

[0020] Figure 3 An illustrative schematic diagram showing the degree of "depth" of a cross-section toward the center of a silicon wafer according to an embodiment of the present invention;

[0021] Figure 4 A schematic diagram of a dimensional acquisition apparatus for detecting the depth of a peripheral damage layer on a silicon wafer, according to an embodiment of the present invention, is shown in conjunction with a front view of the silicon wafer.

[0022] Figure 5 A schematic diagram of a cross-sectional acquisition apparatus for detecting the depth of a peripheral damage layer on a silicon wafer, according to an embodiment of the present invention, is shown in conjunction with a frontal view of the contour variation of the silicon wafer.

[0023] Figure 6 This is a schematic diagram of a polishing unit of a system for detecting the depth of a peripheral damage layer on a silicon wafer according to an embodiment of the present invention;

[0024] Figure 7 This is a schematic diagram of a method for detecting the depth of a peripheral damage layer on a silicon wafer according to an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] See Figure 1 This invention provides a system 1 for detecting the depth d of the peripheral damage layer DL of a silicon wafer W. Figure 1 The diagram schematically illustrates the peripheral damage layer DL of silicon wafer W through a dot-filled area. The system 1 may include:

[0027] A cross-section acquiring device 10 is used to acquire a cross-section S of the silicon wafer W, wherein the cross-section S is perpendicular to the silicon wafer W. It can be understood that the silicon wafer W is flat or planar, and perpendicular to the silicon wafer W means perpendicular to the plane in which the silicon wafer W lies. Therefore, perpendicularity here refers to planes being perpendicular to each other. Figure 1 The cross section S is indicated by a thick solid line in the front view of the silicon wafer shown in the figure;

[0028] Measuring device 20, the measuring device 20 is used to measure the diameter D of the silicon wafer W and to measure the cross-sectional dimension L1 of the cross section S in a first direction FD parallel to the silicon wafer W;

[0029] Size acquisition device 30, the size acquisition device 30 is used to acquire the size L2 of the peripheral damage layer DL in the cross section S and in the first direction FD;

[0030] The computing device 40 is used to calculate the depth d of the peripheral damage layer DL based on the diameter D, the cross-sectional dimension L1 and the damage layer dimension L2.

[0031] For system 1 according to an embodiment of the present invention, compared with the "angle polishing method", the cross section S can be obtained on the basis of the whole silicon wafer W without splitting the silicon wafer W, reducing the process steps in the detection process. In addition, since the silicon wafer W can remain intact, it can be compatible with standard etching machines, thereby simplifying the operation. Finally, the position of the cross section S in the silicon wafer W can be selected as needed, avoiding the situation where the obtained detection surface is only suitable for detecting the thickness of the damage layer on the main surface.

[0032] To simplify the calculation process of depth d by the computing device 40, in a preferred embodiment of the present invention, the computing device 40 can calculate the depth d using the following formula (1):

[0033]

[0034] For details, please refer to [link / reference]. Figure 2 ,pass Figure 2 From the triangular area filled with the horizontal line, we can see that:

[0035]

[0036] pass Figure 2 From the triangular area filled by the central vertical line, we can see that:

[0037]

[0038] In addition, it is easy to understand:

[0039]

[0040] Combining equations (2), (3), and (4) above, we can obtain equation (1). Thus, it is no longer necessary to further refine equations such as... Figure 2 The calculations of L3 and L4 shown in the figure simplify the calculation process of the calculation depth d by the computing device 40.

[0041] The degree to which the aforementioned cross-section S extends toward the center of the silicon wafer W can be arbitrary. However, on the other hand, since the depth of the damaged layer caused by, for example, machining is usually shallow, in this preferred embodiment of the invention, see [reference needed]. Figure 3 For a silicon wafer W with a diameter of 300 mm, the distance SD between the cross section S and the tangent line T parallel to the cross section S and tangent to the outer periphery PC of the silicon wafer W can be between 3 mm and 5 mm. In this way, if the cross section S is obtained entirely by polishing the silicon wafer W, the amount of polishing and the time required can be minimized, thereby improving production efficiency.

[0042] It is understood that for the peripheral damage layer DL of silicon wafer W, the depth d may be different at different circumferential positions. In order to make the depth d detected by system 1 more accurate, in the preferred embodiment of the present invention, see... Figure 4 The size acquisition device 30 may include:

[0043] Measurement unit 31 is used to measure the first damage layer size L2-1 of the first peripheral damage layer DL-1 in the first direction FD in the cross section S and to measure the second damage layer size L2-2 of the second peripheral damage layer DL-2 in the first direction FD in the cross section S.

[0044] The calculation unit 32 is used to calculate the average value of the first damage layer size L2-1 and the second damage layer size L2-2 as the damage layer size L2.

[0045] As previously mentioned, in the "angle polishing method," the sample needs to be angle-polished to form a bevel. The purpose is to better expose defects in the damaged layer on this bevel for measurement. As previously stated, the cross-section S can be obtained entirely by polishing the silicon wafer W. However, in a preferred embodiment of the invention, the dimension acquisition device 30 also acquires the damaged layer dimension L2 based on the defects DE present in the peripheral damaged layer DL and manifested in the cross-section S, and see [reference needed]. Figure 5 The defect DE is schematically shown by points filling the periphery of the silicon wafer W. The cross-section acquisition device 10 may include:

[0046] Cutting unit 11, the cutting unit 11 is used to cut the silicon wafer W in a plane perpendicular to the silicon wafer W to obtain the cutting surface CS of the silicon wafer W;

[0047] Polishing unit 12, the polishing unit is used to polish the cut surface CS to obtain a polished surface PS that is conducive to revealing the defect DE.

[0048] In this way, compared to obtaining the cross-section S entirely through polishing the silicon wafer W, the amount of polishing required is reduced to the greatest extent, although the cut surface CS obtained by cutting is like... Figure 5 The image shows a relatively rough finish that still fails to reveal defects DE, but improves production efficiency by reducing the amount of work required for the time-consuming polishing process.

[0049] Regarding the polishing unit 12 described above, in a preferred embodiment of the present invention, see [reference needed]. Figure 6 The polishing unit 12 may include:

[0050] Clamping mechanism 121, the clamping mechanism 121 is used to clamp the silicon wafer W by contacting the main surface MS of the silicon wafer W;

[0051] Polishing pad 122;

[0052] Drive mechanism 123, the drive mechanism 123 being used to drive the polishing pad 122 to move relative to the clamping mechanism 122, for example in Figure 6 The polishing pad 122 is rotated about its own central axis 122X to polish the silicon wafer W held by the clamping mechanism 122.

[0053] Additionally, it may be necessary to obtain multiple polished surfaces PS at different locations along the circumference of the silicon wafer W. For example, a polished surface PS may be obtained every 45° along the circumference, resulting in a total of 8 polished surfaces PS. These 8 polished surfaces PS are evenly distributed along the circumference of the silicon wafer W to facilitate the detection of a more comprehensive depth d of the peripheral damage layer DL. In this case, for the polishing unit 12 described above, see [reference needed]. Figure 6 The silicon wafer W can be configured to rotate relative to the clamping mechanism 121 around its own central axis WX. In this way, after obtaining a polished surface PS through each polishing operation, it is only necessary to release the silicon wafer W by the clamping mechanism 12, rotate the silicon wafer W by 45°, and finally clamp the silicon wafer W again by the clamping mechanism 12. Then, the previous polishing operation can be repeated to obtain another polished surface PS.

[0054] See Figure 7 and combined Figure 1 This invention also provides a method for detecting the depth of the peripheral damage layer DL of a silicon wafer W, the method comprising:

[0055] S701: Obtain the cross-section S of the silicon wafer W, wherein the cross-section S is perpendicular to the silicon wafer W;

[0056] S702: Measure the diameter D of the silicon wafer W and measure the cross-sectional dimension L1 of the cross section S in the first direction FD parallel to the silicon wafer W;

[0057] S703: Obtain the damage layer size L2 of the peripheral damage layer DL in the cross section S and in the first direction FD;

[0058] S704: Calculate the depth d of the peripheral damage layer DL based on the diameter D, the cross-sectional dimension L1, and the damage layer dimension L2.

[0059] Preferably, as described above, in combination with Figure 2 The depth d can be calculated using the following formula:

[0060]

[0061] Preferably, see Figure 4 The step of obtaining the damage layer size L2 of the peripheral damage layer DL in the cross section S and in the first direction FD may include:

[0062] Measure the first damage layer size L2-1 of the first peripheral damage layer DL-1 in the first direction FD in the cross section S, and measure the second damage layer size L2-2 of the second peripheral damage layer DL-2 in the first direction FD in the cross section S;

[0063] The average value of the first damage layer size L2-1 and the second damage layer size L2-2 is calculated as the damage layer size L2.

[0064] Preferably, the damage layer size L2 is obtained based on the defect DE present in the peripheral damage layer DL and manifested in the cross section S, and see also... Figure 5 Obtaining the cross-section S of the silicon wafer W may include:

[0065] The silicon wafer W is cut in a plane perpendicular to the silicon wafer W to obtain the cut surface CS of the silicon wafer W;

[0066] The cut surface CS is polished to obtain a polished surface PS that is conducive to revealing the defect DE.

[0067] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A system for detecting the depth of a peripheral damage layer on a silicon wafer, characterized in that, The system includes: A cross-section acquisition device is used to acquire a cross-section of a silicon wafer, wherein the cross-section is perpendicular to the plane in which the silicon wafer is located, and the cross-section of the silicon wafer includes a non-damaged layer cross-section in the middle of the silicon wafer and peripheral damaged layer cross-sections on both sides of the silicon wafer. A measuring device for measuring the diameter of the silicon wafer and the cross-sectional length of the cross section in a first direction parallel to the plane in which the silicon wafer lies; A dimension acquisition device, the dimension acquisition device being used to acquire the length dimension of the peripheral damage layer on one side in the cross section and in the first direction; A computing device is configured to calculate the depth of the peripheral damage layer based on the diameter, the cross-sectional length dimension, and the damage layer length dimension. Wherein, the diameter is set to D, the cross-sectional length is L1, and the damaged layer length is L2, the computing device calculates the depth d using the following formula: 。 2. The system according to claim 1, characterized in that, For a silicon wafer with a diameter of 300 mm, the distance between the cross section and the tangent line that is parallel to the cross section and tangent to the outer periphery of the silicon wafer is between 3 mm and 5 mm.

3. The system according to claim 1, characterized in that, The size acquisition device includes: The measuring unit is used to measure the length of the first peripheral damage layer on one side of the cross section in the first direction and to measure the length of the second peripheral damage layer on the other side of the cross section in the first direction. The calculation unit is used to calculate the average value of the first damage layer length dimension and the second damage layer length dimension as the damage layer length dimension.

4. The system according to claim 1, characterized in that, The dimension acquisition device acquires the length dimension of the damage layer based on defects present in the peripheral damage layer and manifested in the cross-section, and the cross-section acquisition device includes: A cutting unit is used to cut the silicon wafer in a plane perpendicular to the plane on which the silicon wafer is located to obtain a cut surface of the silicon wafer; A polishing unit is used to polish the cut surface to obtain a polished surface that reveals the defect.

5. The system according to claim 4, characterized in that, The polishing unit includes: A clamping mechanism for clamping the silicon wafer by contacting its main surface; Polishing pad; A driving mechanism is provided for driving the polishing pad to move relative to the clamping mechanism in order to polish the silicon wafer held by the clamping mechanism.

6. A method for detecting the depth of a peripheral damage layer on a silicon wafer, characterized in that, The method includes: Obtain a cross-section of the silicon wafer, wherein the cross-section is perpendicular to the plane in which the silicon wafer is located, and the cross-section of the silicon wafer includes the cross-section of the undamaged layer in the middle of the silicon wafer and the cross-section of the peripheral damaged layer on both sides of the silicon wafer; The diameter of the silicon wafer is measured, and the cross-sectional length of the cross-section is measured in a first direction parallel to the plane in which the silicon wafer lies. Obtain the length dimension of the peripheral damage layer on one side in the cross section and in the first direction; The depth of the peripheral damage layer is calculated based on the diameter, the cross-sectional length, and the damage layer length. Wherein, the diameter is set as D, the cross-sectional length is L1, and the damaged layer length is L2, the depth d is calculated using the following formula: 。 7. The method according to claim 6, characterized in that, The step of obtaining the length dimension of the peripheral damage layer on one side in the cross section and in the first direction includes: Measure the length of the first peripheral damage layer on one side of the cross section in the first direction and measure the length of the second peripheral damage layer on the other side of the cross section in the first direction; The average of the length dimensions of the first and second damaged layers is calculated as the length dimension of the damaged layer.

8. The method according to claim 6, characterized in that, The length of the damaged layer is obtained based on defects present in the peripheral damaged layer and manifested in the cross-section, and obtaining the cross-section of the silicon wafer includes: The silicon wafer is cut in a plane perpendicular to the plane in which it lies to obtain the cut surface of the silicon wafer; The cut surface is polished to obtain a polished surface that reveals the defect.

Images