Wafer grinding device
By using optical sensing components and controllers to adjust the mobile components in the wafer grinding device, the problem of flat edge position offset in the wafer grinding device during the edge search process is solved, and the wafer surface type accuracy and vacuum adsorption accuracy are improved. Reduces the risk of flying films and fragments.
Patent Information
- Application Number
- CN202420876797.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-25
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2034-04-25
AI Technical Summary
Existing wafer grinding devices are prone to flat edge position deviation during edge search, resulting in imperfect vacuum adsorption, affecting the wafer surface accuracy, and increasing the risk of fly wafers and chips.
Using a wafer grinding device including a carrier assembly, a light source assembly and an optical sensing assembly, the optical sensing assembly receives a light beam projected on the isolation layer through the optical sensing assembly, determines the overlap between the wafer center and the rotation axis, and adjusts the moving assembly through the controller to Compensate for deviations to ensure accurate neutralization of the wafer.
Improves the wafer surface accuracy, reduces the risk of flying chips and chips, and ensures the stability and accuracy of the wafer processing process.
Smart Images
Figure CN222155155U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of semiconductor chip processing, and in particular to a wafer grinding device. Background Art
[0002] Wafers are the basis of semiconductors, and the production of semiconductor integrated circuits is achieved by manufacturing multiple identical circuits on a thin wafer substrate. Wafers that have been processed by the front-end process and passed the wafer test will start the back-end processing from back grinding. Back grinding is the process of grinding the back of the wafer thinner. Its purpose is not only to reduce the thickness of the wafer, but also to connect the front-end and back-end processes to solve problems that arise between the two processes. The thinner the semiconductor chip, the more chips can be stacked and the higher the integration. However, the higher the integration may lead to a decrease in product performance. Therefore, there is a contradiction between integration and improving product performance. Therefore, the grinding method that determines the thickness of the wafer is one of the keys to reducing the cost of semiconductor chips and determining product quality.
[0003] At present, self-rotation grinding is widely used in the processing of thin wafers, which uses a rotating grinding wheel to orderly remove surface materials on the wafer surface. Wafer self-rotation grinding can simultaneously increase the grinding wheel speed and grinding wheel feed rate, improve grinding efficiency, and can achieve micro-grinding by increasing the grinding wheel speed.
[0004] However, the current wafer edge-finding method is not based on the actual position of the grinding table, but on the centering stage, according to the position of the grinding table, the flat edge is found through the results of the internal sensor. Therefore, in the actual processing process, it is very easy for the flat edge position to shift, resulting in an imperfect vacuum adsorption area, thus affecting the wafer surface accuracy. Insufficient vacuum can also cause equipment alarms and even wafer breakage. Utility Model Content
[0005] In order to solve the deficiencies of the prior art, the purpose of the present application is to provide a wafer grinding device that can automatically find edges during wafer thinning processing and can improve the surface accuracy of the wafer.
[0006] To achieve the above objectives, this application adopts the following technical solutions:
[0007] A wafer grinding device comprises a bearing assembly, a light source assembly, an optical sensing assembly and a moving assembly. The bearing assembly is used for bearing a wafer and defines a rotation axis parallel to a vertical direction. The bearing assembly can drive the wafer to rotate around the rotation axis. The bearing assembly comprises an adsorption layer, a vacuum passage and an isolation layer. The adsorption layer is circumferentially distributed around the rotation axis. The vacuum passage passes through the bearing assembly in a vertical direction. One end of the vacuum passage is connected to the adsorption layer. The isolation layer is annular and circumferentially distributed around the adsorption layer. The outer diameter of the isolation layer is equal to or substantially equal to the radial length of the wafer. The isolation layer and the adsorption layer are both arranged on a side of the bearing assembly facing the moving assembly. The light source assembly is arranged on a side of the wafer away from the bearing assembly and is used to generate a light beam perpendicular to the wafer. The optical sensing assembly is installed on the isolation layer and is used to receive the light beam generated by the light source assembly. The moving assembly is electrically connected to the optical sensing assembly and is used to grab the wafer.
[0008] Furthermore, the radial length of the outer edge of the adsorption layer is smaller than the radial length of the wafer.
[0009] Furthermore, the wafer grinding device includes a plurality of optical sensor components, and the plurality of optical sensor components are evenly distributed on the isolation layer along the circumference of the isolation layer.
[0010] Furthermore, the supporting component includes multiple working layers for adsorbing wafers of different sizes, wherein any working layer is composed of an adsorption layer and an isolation layer, the center of any working layer coincides with the rotation axis, and no two adjacent working layers overlap.
[0011] Furthermore, two adjacent working layers are respectively defined as a first working layer and a second working layer. The first working layer is horizontally arranged around the outer edge of the second working layer. The first working layer includes a first adsorption layer and a first isolation layer. The second working layer includes a second adsorption layer and a second isolation layer. The second isolation layer is arranged around the outer edge of the second adsorption layer. The first adsorption layer is arranged around the outer edge of the second isolation layer. The first isolation layer is arranged around the outer edge of the first adsorption layer.
[0012] Furthermore, the wafer grinding device includes a controller connected to the optical sensing component, the light beam generated by the light source component irradiates the wafer and generates a projection of the wafer on the isolation layer, the controller determines the area of the overlapping part between the projection of the wafer and the area surrounded by the outer edge of the isolation layer according to the electrical signal sent by the optical sensing component, and the controller determines whether the center of the wafer coincides with the rotation axis according to the ratio of the area of the overlapping part to the area of the projection.
[0013] Further, according to a calibration threshold set in the controller, when the controller determines that the ratio of the area of the overlapping portion to the area of the projection is greater than or equal to the calibration threshold, it is determined that the center of the wafer coincides with the rotation axis.
[0014] Furthermore, the optical sensing component is electrically connected to the moving component through the controller, and the electrical signals sent to the controller by the optical sensing component blocked by the projection and the optical sensing component not blocked by the projection are respectively defined as a first electrical signal and a second electrical signal. The controller fits the center point of the projection circle according to the first electrical signal and the second electrical signal, and controls the moving component to move in a direction perpendicular to the rotation axis according to the deviation between the center point of the circle and the rotation axis to compensate for the deviation.
[0015] Furthermore, the controller is set with multiple adjustment directions parallel to the horizontal direction. The controller controls the moving component to move along a first adjustment direction and updates the deviation during the movement of the moving component. If the updated deviation is greater than the deviation before the update, the controller controls the moving component to move along a second adjustment direction, wherein the second adjustment direction is opposite to the first adjustment direction.
[0016] Furthermore, the controller calibrates the mark points of each optical sensing component in the horizontal direction. The controller determines the mark points of the optical sensing components that are not blocked by the projection based on the second electrical signal, fits the center points of the projected circle through the mark points, and controls the moving component to move in a direction perpendicular to the rotation axis based on the deviation between the center point of the circle and the rotation axis to compensate for the deviation.
[0017] The wafer grinding device is configured with an isolation layer having the same radius as the wafer and an optical sensing component on the isolation layer. The light source component illuminates the wafer to generate a projection of the wafer on the isolation layer, and then compares the area surrounded by the isolation layer with the projection of the wafer to determine whether the position of the wafer is offset, thereby ensuring the vacuum adsorption accuracy of the wafer and reducing the risk of flying wafers and broken wafers during processing. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 A schematic diagram of a wafer grinding device according to an embodiment of the present application;
[0019] Figure 2 A cross-sectional view of a wafer grinding device in an embodiment of the present application;
[0020] Figure 3 A top view of a wafer grinding device in an embodiment of the present application;
[0021] Figure 4 A schematic diagram of the deviation between the center of a wafer and the rotation axis in an embodiment of the present application;
[0022] FIG5( a) is a schematic diagram of a wafer of a first size in an embodiment of the present application;
[0023] FIG. 5( b ) is a schematic diagram of a wafer of a second size in an embodiment of the present application. DETAILED DESCRIPTION
[0024] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the specific implementation manner of the present application will be clearly and completely described below in conjunction with the drawings in the implementation manner of the present application.
[0025] like Figure 1 As shown, the present application provides a wafer grinding device 100, which includes a supporting component 11 and a moving component (not shown), wherein the supporting component 11 is used to support the wafer 200, defines a rotation axis 101 parallel to the vertical direction, and the supporting component 11 can drive the wafer 200 to rotate around the rotation axis 101; the moving component is arranged above the supporting component 11, and grabs the wafer 200, and drives the wafer 200 to move in a direction perpendicular to the rotation axis 101.
[0026] Specifically, when the moving component drives the wafer 200 to move above the supporting component 11 and the center of the wafer 200 coincides with the rotating axis 101 , the moving component drives the wafer 200 to move downward until the wafer 200 is placed on the supporting component 11 to achieve centering of the wafer 200 .
[0027] In order to solve the problem that the wafer centering deviation in the related art leads to the risk of wafer flying and breaking due to the wafer not being completely adsorbed on the carrier component during wafer processing, the present application provides the following technical solutions:
[0028] like Figure 1 and Figure 2 As shown, as an implementation method, the carrier component 11 includes an adsorption layer 111, an isolation layer 112 and a vacuum passage 113, wherein the adsorption layer 111 and the isolation layer 112 are both arranged on the side of the carrier component 11 facing the moving component, and when the wafer 200 is arranged on the carrier component 11, the wafer 200 is covered on the adsorption layer 111 and the isolation layer 112.
[0029] Specifically, the adsorption layer 111 is distributed circumferentially around the rotation axis 101 , and the center of the adsorption layer 111 substantially coincides with the rotation axis 101 .
[0030] The vacuum passage 113 vertically penetrates the carrier assembly 11, and one end of the vacuum passage 113 is connected to the adsorption layer 111, and the other end of the vacuum passage 113 is connected to a vacuum region. By applying negative pressure in the vacuum region, the adsorption layer 111 generates an adsorption force on the wafer 200 toward the vacuum region, thereby fixing the wafer 200.
[0031] It is understandable that if there is a deviation in the centering of the wafer 200 , the adsorption force of the adsorption layer 111 on the wafer 200 may be reduced, thereby causing the risk of flying chips or broken chips during the processing of the wafer 200 .
[0032] Furthermore, the isolation layer 112 is annular and is distributed around the circumference of the adsorption layer 111. The outer diameter of the isolation layer 112 is substantially consistent with the radial length of the wafer 200. Therefore, when the center of the wafer 200 coincides with the rotation axis 101, the projection of the wafer 200 in the vertical direction completely coincides with the area surrounded by the outer edge of the isolation layer 112.
[0033] In an embodiment of the present application, the radial length of the outer edge of the adsorption layer 111 is smaller than the radial length of the wafer 200, so that when the wafer 200 is covered on the supporting component 11 and the center of the wafer 200 coincides with the rotation axis 101, the wafer 200 can completely cover the adsorption layer 111, thereby improving the stability of the wafer 200 during processing.
[0034] like Figure 1 and Figure 3 As shown, the wafer grinding device 100 further includes a light source component 12 and an optical sensor component 13. The light source component 12 is disposed on the side of the wafer 200 away from the supporting component 11, and the light source component 12 is used to generate a light beam perpendicular to the wafer 200. The optical sensor component 13 is disposed on the isolation layer 112, and the wafer grinding device 100 includes a plurality of optical sensor components 13, and the plurality of optical sensor components 13 are evenly distributed on the isolation layer 112 along the circumference of the isolation layer 112.
[0035] The wafer grinding device 100 also includes a controller (not shown) connected to the optical sensing component 13. The light source component 12 generates a light beam perpendicular to the wafer 200 and generates a projection of the wafer 200 on the isolation layer 112. The controller determines the area of the overlapping portion between the projection of the wafer 200 and the area surrounded by the outer edge of the isolation layer 112 based on the electrical signal sent by the optical sensing component 13. The controller determines whether the center of the wafer 200 coincides with the rotation axis 101 based on the ratio between the area of the overlapping portion and the area of the projection.
[0036] like Figure 4 As shown, illustratively, the optical sensor assembly 13 is disposed at the outer edge of the isolation layer 112, the light source assembly 12 generates a light beam perpendicular to the wafer 200, and generates a projection of the wafer 200 on the isolation layer 112, the optical sensor assembly 13 blocked by the projection generates a first electrical signal, and the optical sensor assembly 13 not blocked by the projection generates a second electrical signal. The controller determines the positions of the blocked optical sensor assemblies 13 according to the first electrical signal and the second electrical signal, and fits the projection's circular center point 102 accordingly.
[0037] Furthermore, the controller determines the deviation D between the center of the wafer 200 and the rotation axis 101 according to the circumferential center point 102 and the rotation axis 101 , and controls the moving component to move in the horizontal direction to compensate for the deviation D.
[0038] As an implementation manner, a calibration threshold is provided in the controller for measuring whether the center of the wafer 200 coincides with the rotation axis 101 .
[0039] The controller determines the area of the overlapping portion of the projection of the wafer 200 and the area surrounded by the outer edge of the isolation layer 112 according to the electrical signal sent by the optical sensing component 13. In the example of the present application, the area of the above-mentioned overlapping portion is defined as the first area, and the area of the projection of the wafer 200 is defined as the second area, wherein the first area is less than or equal to the second area. The controller determines the ratio of the first area to the second area, and when the ratio is greater than or equal to the calibration threshold, the controller determines that the center of the wafer 200 coincides with the rotation axis 101, and then controls the moving component to place the wafer 200 on the carrier component 11.
[0040] Exemplarily, the calibration threshold is 95%, and when the ratio of the first area to the second area is greater than or equal to 95%, it indicates that the center of the wafer 200 coincides with the rotation axis 101 .
[0041] Since the radial length of the wafer 200 is greater than the radial length of the outer edge of the adsorption layer 111 , there can be a certain error between the center of the wafer 200 and the rotation axis 101 in the horizontal direction, and it can also ensure that the adsorption force of the adsorption layer 111 on the wafer 200 will not be reduced.
[0042] As an implementation method, the controller is provided with multiple adjustment directions parallel to the horizontal direction. The controller controls the moving component to move along a first adjustment direction, and updates the deviation D during the movement of the moving component. If the updated deviation D2 is greater than the deviation D1 before the update, the controller controls the moving component to move along a second adjustment direction, wherein the second adjustment direction is opposite to the first adjustment direction.
[0043] Exemplarily, with the center of the wafer 200 as the center point, the controller is provided with 6 adjustment directions starting from the center point and extending along the radial direction of the wafer 200, and the angle between two adjacent adjustment directions is 60°. The controller controls the moving component to move along any of the above 6 adjustment directions, and adjusts the moving component in turn according to the adjustment direction until the deviation D between the center of the wafer 200 and the rotation axis 101 reaches the minimum value.
[0044] It should be noted that the above-mentioned setting of 6 adjustment directions is only an example, and the controller can also be set to 8 or 10 adjustment directions to more accurately adjust the position of the wafer 200 so that the center of the wafer 200 coincides with the rotation axis 101.
[0045] Optionally, the controller calibrates the mark points of each optical sensing component 13 in the horizontal direction. The controller determines the mark points of the optical sensing components 13 that are not blocked by the projection based on the second electrical signal, fits the projected circular center point 102 through the mark points, and controls the moving component to move in a direction perpendicular to the rotation axis 101 based on the deviation D between the circular center point 102 and the rotation axis 101 to compensate for the deviation D.
[0046] As an implementation, the carrier assembly 11 includes multiple working layers for adsorbing wafers 200 of different sizes. Each working layer is composed of an adsorption layer 111 and an isolation layer 112, and the center of each working layer coincides with the rotation axis 101, and two adjacent working layers do not coincide with each other.
[0047] In the example of the present application, the bearing assembly 11 includes two working layers, and the two working layers are respectively defined as a first working layer and a second working layer. The first working layer and the second working layer are both distributed circumferentially around the rotating axis 101, and the first working layer is arranged horizontally around the outer edge of the second working layer.
[0048] Specifically, the first working layer includes a first isolation layer 112 and a first adsorption layer 111, and the second working layer includes a second isolation layer 112 and a second adsorption layer 111. The second isolation layer 112 is arranged around the outer edge of the second adsorption layer 111, the first adsorption layer 111 is arranged around the outer edge of the second isolation layer 112, and the second isolation layer 112 is arranged around the outer edge of the second adsorption layer 111.
[0049] Exemplarily, the wafer grinding apparatus 100 is used to process a wafer 200 of a first size and a wafer 200 of a second size, wherein a radial length of the wafer 200 of the first size is greater than a radial length of the wafer 200 of the second size.
[0050] As shown in Figure 5(a), when the wafer grinding device 100 processes a wafer 200 of a first size, the wafer 200 of the first size covers the first working layer. When the center of the wafer 200 coincides with the rotation axis 101, the wafer 200 of the first size coincides with the first isolation layer 112 in the vertical direction.
[0051] As shown in Figure 5(b), when the wafer grinding device 100 processes the second-sized wafer 200, the second-sized wafer 200 covers the second working layer. When the center of the wafer 200 coincides with the rotation axis 101, the second-sized wafer 200 coincides with the second isolation layer 112 in the vertical direction.
[0052] In summary, by setting an isolation layer 112 with the same radius as the wafer 200, and providing an optical sensing component 13 on the isolation layer 112, the light source component 12 irradiates the wafer 200 to generate a projection of the wafer 200 on the isolation layer 112, and then compares the area surrounded by the isolation layer 112 with the projection of the wafer 200 to determine whether the position of the wafer 200 is offset, thereby ensuring the vacuum adsorption accuracy of the wafer 200 and reducing the risk of flying chips and breakage during wafer 200 processing.
[0053] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the claims attached to this application.
Claims
1. A wafer grinding device, characterized in that: include: A bearing assembly for bearing a wafer and a moving assembly for grabbing the wafer define a rotation axis parallel to the vertical direction, and the bearing assembly can drive the wafer to rotate around the rotation axis. The bearing assembly includes: an adsorption layer, the adsorption layer being distributed circumferentially around the rotation axis; A vacuum passage, the vacuum passage vertically penetrating the bearing assembly, one end of the vacuum passage being connected to the adsorption layer; An isolation layer, the isolation layer is annular and distributed circumferentially around the adsorption layer, the outer diameter of the isolation layer is equal to or substantially equal to the radial length of the wafer, and the isolation layer and the adsorption layer are both arranged on a side of the bearing component facing the moving component; A light source assembly, used for generating a light beam perpendicular to the wafer, wherein the light source assembly is disposed on a side of the wafer away from the supporting assembly; The optical sensor component is used to receive the light beam generated by the light source component. The optical sensor component is electrically connected to the moving component and is installed on the isolation layer.
2. The wafer grinding device according to claim 1, characterized in that: The radial length of the outer edge of the adsorption layer is smaller than the radial length of the wafer.
3. The wafer grinding device according to claim 1, characterized in that: The wafer grinding device comprises a plurality of the optical sensing components, and the plurality of the optical sensing components are evenly distributed on the isolation layer along the circumference of the isolation layer.
4. The wafer grinding device according to claim 1, characterized in that: The supporting component includes a plurality of working layers for adsorbing wafers of different sizes, wherein any of the working layers is composed of an adsorption layer and an isolation layer, the center of any of the working layers coincides with the rotation axis, and no two adjacent working layers overlap.
5. The wafer grinding device according to claim 4, characterized in that: The two adjacent working layers are respectively defined as the first working layer and the second working layer, the first working layer is horizontally arranged around the outer edge of the second working layer, the first working layer includes a first adsorption layer and a first isolation layer, the second working layer includes a second adsorption layer and a second isolation layer, the second isolation layer is arranged around the outer edge of the second adsorption layer, the first adsorption layer is arranged around the outer edge of the second isolation layer, and the first isolation layer is arranged around the outer edge of the first adsorption layer.
6. The wafer grinding device according to claim 1, characterized in that: The wafer grinding device also includes a controller, the optical sensing component is electrically connected to the controller, the light beam generated by the light source component irradiates the wafer and generates a projection of the wafer on the isolation layer, the controller determines the area of the overlapping part between the projection of the wafer and the area surrounded by the outer edge of the isolation layer according to the electrical signal sent by the optical sensing component, and the controller determines whether the center of the wafer coincides with the rotation axis according to the ratio of the area of the overlapping part to the area of the projection.
7. The wafer grinding device according to claim 6, characterized in that: According to a calibration threshold set in the controller, when the controller determines that the ratio of the area of the overlapping portion to the area of the projection is greater than or equal to the calibration threshold, it is determined that the center of the wafer coincides with the rotation axis.
8. The wafer grinding device according to claim 6, characterized in that: The optical sensing component is electrically connected to the moving component through the controller, and the electrical signals sent to the controller by the optical sensing component blocked by the projection and not blocked by the projection are defined as a first electrical signal and a second electrical signal, respectively. The controller fits the circular center point of the projection according to the first electrical signal and the second electrical signal, and controls the moving component to move in a direction perpendicular to the rotation axis according to the deviation between the circular center point and the rotation axis to compensate for the deviation.
9. The wafer grinding device according to claim 8, characterized in that: The controller is set with multiple adjustment directions parallel to the horizontal direction. The controller controls the moving component to move along a first adjustment direction and updates the deviation during the movement of the moving component. If the deviation after the update is greater than the deviation before the update, the controller controls the moving component to move along a second adjustment direction, wherein the second adjustment direction is opposite to the first adjustment direction.
10. The wafer grinding device according to claim 8, characterized in that: The controller calibrates the mark points of each optical sensing component in the horizontal direction, determines the mark points of the optical sensing components that are not blocked by the projection based on the second electrical signal, fits the circular center points of the projection through the mark points, and controls the movement of the moving component in a direction perpendicular to the rotation axis based on the deviation between the circular center point and the rotation axis to compensate for the deviation.