Microporous ceramic chuck

Abstract

The present application relates to the field of wafer inspection, and discloses a microporous ceramic chuck. The microporous ceramic chuck is circular, a plurality of ceramic annular platforms of different diameters are distributed on a chuck surface, and said ceramic annular platforms are arranged concentrically with the circular chuck surface; a vacuum annular groove is formed between adjacent ceramic annular platforms, and vacuum suction holes are formed in the vacuum annular groove; linear micropores each consisting of a plurality of circular micropores are formed on different ceramic annular platforms, and the micropore centers of the linear micropores are collinear; the micropores centers located on different ceramic annular platforms are collinear with the center of the chuck surface; and each ceramic annular platform is provided with at least two groups of linear micropore arrays in different directions and collinear with the center of the chuck surface. Using circular micropores instead of scribing or slotting methods can avoid the problem of uneven line width affecting image calibration accuracy at high‑precision pixel levels. Using a straight line simulated by a line connecting the centers can further improve the accuracy; combined with high‑contrast particle filling and non‑linear hole patterns, the image size at the algorithm / software level is minimized, and multi‑particle recognition allows for more precise straight‑line determination.

Description

Microporous ceramic suction cup Technical Field

[0001] This application relates to the field of wafer inspection, and in particular to a microporous ceramic chuck. Background Technology

[0002] Wafer manufacturing and processing are complex and interconnected, resulting in high production costs and stringent quality requirements for each process. In actual production, every step from wafer substrate design to final etching requires quality inspection. This allows for the timely detection of quality issues in wafer products, enabling process adjustments or the scrapping of defective wafers to minimize losses. Technical issues

[0003] In related technologies, a stage chuck is used to receive wafers transferred by a robotic arm. To smoothly move the wafer from the robotic arm's grippers to the chuck, grooves are typically provided to support the arm's movement. However, due to the bending and warping of the wafer, the two gripping arms cannot fully support it. This means that the gripping arms may break when the chuck picks up the wafer. Therefore, a new gripping scheme and gripping arms have been designed, making the original grooved chuck unsuitable. Furthermore, even after the robotic arm places the aligned wafer onto the tray, errors still exist. Wafers without secondary offset correction have an error of 1mm, which translates to a deviation of approximately 500 pixels in a 2.5-micron pixel image, severely impacting wafer defect detection. Technical solutions

[0004] This application provides a microporous ceramic chuck to solve the problem of inaccurate wafer alignment in related technologies. The microporous ceramic chuck is circular, with several ceramic abutments of different diameters distributed on its surface, and the ceramic abutments of different diameters are arranged concentrically with the circular surface.

[0005] A vacuum ring groove is formed between adjacent ceramic ring stages, and a vacuum suction hole is provided in the vacuum ring groove to adsorb the wafer supported by the ceramic ring stage.

[0006] Linear micropores composed of several circular micropores are formed on different ceramic rings, and the centers of the micropores are collinear; the centers of the micropores on different ceramic rings are collinear with the center of the disk surface; at least two sets of linear micropore arrays with different directions and collinear with the center of the disk surface are provided on each ceramic ring for wafer calibration based on the connection line of the centers of the micropores in the linear micropore array.

[0007] Specifically, at least one vacuum suction hole is provided in each of the vacuum ring grooves, and the vacuum suction hole is a circular through hole that penetrates the disk surface, with the bottom of the hole connected to a gas source through a gas passage.

[0008] Specifically, the vacuum suction holes located in different vacuum ring grooves are linearly distributed, and the center of the diameter of the linearly distributed vacuum suction holes is collinear with the center of the disk surface.

[0009] Specifically, the linear micropores on the ceramic ring include at least three circular micropores of the same structural size, and each circular micropore is filled with a white filler.

[0010] Specifically, the substrate of the microporous ceramic suction cup is an alumina matrix, and the ceramic ring and the surface of the cup are hard anodized and treated to be black.

[0011] Specifically, the ceramic disk in the vacuum ring groove is black and has honeycomb micropores on its surface.

[0012] Specifically, three ceramic ring platforms are set on the disc surface, with diameters greater than 125mm, 210mm and 320mm respectively.

[0013] Specifically, the diameter of the circular micropores does not exceed 0.5 mm, and the distance between the centers of adjacent circular micropores does not exceed 0.75 mm.

[0014] Specifically, each of the ceramic rings is also evenly distributed with several mounting holes, and the mounting holes on different ceramic rings are staggered.

[0015] Specifically, the diameter of the circular micropore does not exceed 5 mm, and the distance between the centers of two vacuum suction holes in adjacent vacuum ring grooves does not exceed 27 mm. Beneficial effects

[0016] The beneficial effects of the technical solution provided in this application include at least the following: This application uses a ceramic-structured suction cup as a wafer stage, and ceramic ring stages with different inner diameters are set on the disk surface to support wafers of various sizes. Vacuum ring grooves are formed between all the ceramic ring stages, and vacuum suction holes opened in them can create negative pressure to fix the wafer on the disk surface. The linear micro-holes opened on the ceramic ring stages are composed of several circular micro-holes, filled with a filler of a different color from the ceramic substrate to form high contrast. Using circular micro-holes instead of scribing or grooving can avoid the problem of uneven image correction accuracy under high-precision pixels. The straight lines simulated by connecting the centers of the circles can further improve accuracy. Combined with high-color-difference particle filling and non-linear openings, the image of the soft layer is smaller, and the identification of multiple particles to determine the straight line is more accurate. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the wafer loading misalignment correction system;

[0018] Figure 2 is a schematic diagram of wafer loading misalignment correction provided in an embodiment of this application;

[0019] Figure 3 is a schematic diagram of the structure of the microporous ceramic suction cup provided in the embodiment of this application;

[0020] Figure 4 is a top view of the ceramic suction cup;

[0021] Figure 5 is an enlarged view of point A in Figure 4;

[0022] Figure 6 is a schematic diagram showing the linear micropores set in the form of crosshairs;

[0023] Figure 7 is an enlarged view of point B in Figure 6;

[0024] Figure 8 is a schematic diagram showing the location of the vacuum suction holes in the vacuum ring groove;

[0025] Figure 9 is a cross-sectional view at point A in Figure 4;

[0026] Figure 10 is a cross-sectional view of point B in Figure 8. Embodiments of the present invention

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0028] In this article, "multiple" refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0029] Figure 1 is a schematic diagram of a wafer loading misalignment correction system, including an inspection platform 110 with an attitude adjustment mechanism 120 mounted on it, and a stage 130 located at the top of the attitude adjustment mechanism 120. Traditional defect detection schemes also require a stage, with a basic structure similar to the stage in Figure 1. However, the difference lies in the fact that the stage 130 in this application is controlled by the attitude adjustment mechanism 120 and can be raised, lowered, and adjusted in terms of displacement angle as needed, i.e., it can change arbitrarily within a spatial range. The stage 130 is typically circular, maintaining the shape of the wafer 140 to be tested. Misalignment correction in this application is mainly achieved through the attitude adjustment mechanism 120. Furthermore, because the stage 130 is controlled to move in a three-dimensional plane, suction cups or suction holes are needed on the stage 130 to ensure that the wafer 140 to be tested is firmly fixed on it.

[0030] After the wafer is placed onto the stage by a robotic arm, a camera fixed directly above or at a specific position on the stage scans the wafer's position, creating a wafer state image. This application uses a circular stage as an example. Theoretically, the wafer should be gripped and placed at the center of the stage. However, due to errors and other factors, the wafer cannot actually be precisely placed at the center. Figure 2 shows the stage 210 before wafer loading on the left. To facilitate subsequent determination of stage deviation, a target area 220 can be set on the stage 210. This target area can be a raised or recessed mark etched on the stage 210. As shown in the wafer state image on the right of Figure 2, the blue area represents the wafer 240 after loading. A significant positional deviation between the wafer 240 area and its outline can be directly observed in the image. Based on this positional deviation, the positional information of the wafer 240 relative to the stage 210 can be extracted to represent the actual position of the wafer 240. The significant positional deviation between the wafer 240 and the target area 220 is the reason for the correction.

[0031] This application designs a microporous ceramic suction cup with an annular groove as the target, and obtains the microporous ceramic suction cup shown in Figure 3. The ceramic suction cup is used as the stage component in Figure 2. The microporous ceramic suction cup is circular, and several ceramic ring stages 1 of different diameters are distributed on the upward disk surface. The ceramic ring stages 1 of different diameters are arranged with the circular disk surface at the same center, forming a concentric circle layout corresponding to each ceramic ring stage 1 in Figure 3.

[0032] Because the wafer must not shift relative to the stage during the movement process, a vacuum ring groove 2 is formed in the recess between adjacent ceramic ring stages 1. Several vacuum suction holes can be set in the vacuum ring groove 2 to pick up the wafer supported by the ceramic ring stage.

[0033] Linear micro-holes 3, composed of several circular micro-holes, are formed on different ceramic rings 1. Each linear micro-hole contains several circular micro-holes, and the centers of all the circular micro-holes are collinear. Figure 4 is a top view of the ceramic chuck, where A marks a linear micro-hole on one of the ceramic rings 1. Figure 5 is an enlarged view of point A in Figure 4. As can be seen from Figure 4, the centers of the micro-holes on different ceramic rings are collinear with the center of the disk surface. Because wafer correction requires the use of coordinate systems and auxiliary lines as references, multiple sets of linear micro-holes 3 are set in multiple directions on the ceramic disk, so that the centers of the micro-holes 3 and the center of the disk surface form a straight line. This is equivalent to directly engraving natural auxiliary lines on the disk surface as references.

[0034] In one possible implementation, at least two sets of linear microvia arrays with different orientations and collinear with the center of the disk surface can be provided on each ceramic ring stage for wafer calibration based on the connection line between the centers of the microvias in the linear microvia array. Assuming that the system calibration uses a Cartesian coordinate system for alignment calibration, a crosshair pattern is used for setting. Figure 6 is a schematic diagram of the linear microvias set in the form of crosshairs, and Figure 7 is an enlarged view of point B in Figure 6. It can be seen from the figure that the linear microvias 3 on adjacent ceramic ring stages 1 are collinearly set (with the centers of the microvias collinear).

[0035] As shown in Figure 5, in one possible implementation, each group of linear micro-holes 3 on the ceramic ring 1 contains at least three circular micro-holes of the same structural size, and each circular micro-hole is filled with white filler or filler with a color gradation significantly different from the background of the ceramic suction cup, for rapid identification in the image. The red lines in Figure 6 are equivalent to the red auxiliary lines constructed during image processing in the correction stage in Figure 2, which are equivalent to the constructed coordinate system. The diameter of the circular micro-holes is set to no more than 0.5 mm, and the distance between the centers of adjacent circular micro-holes is no more than 0.75 mm. This ensures that the image acquired by the high-precision line scan camera will not be distorted after magnification. Assuming that lines are drawn on the disk surface, uneven line thickness will inevitably appear after high-precision magnification. This is because the wafer without secondary offset correction has an error of 1 mm, which is reflected in an image with a pixel size of 2.5 micrometers, resulting in a deviation of about 500 pixels. The uneven line thickness will be magnified, and the center line cannot be selected, ultimately leading to a larger error in the correction result. The grooving method is also affected by the accuracy. Therefore, this application uses a linear hole method as a reference, and the center of the circular micro-hole can be used as the connection standard, so that the accuracy of establishing auxiliary lines and coordinate system is higher.

[0036] In some possible implementations, in order to accommodate wafers of various sizes, three ceramic ring stages can be set on the disk surface, with the inner or outer ring diameters being greater than 125mm, 210mm and 320mm respectively, so as to be able to pick up at least three wafers of different sizes.

[0037] As shown in Figure 8, to ensure that wafers of different sizes can be adsorbed without falling off, at least one vacuum suction hole 21 can be provided in each vacuum ring groove 2. The vacuum suction hole 21 is a circular through hole that penetrates the disk surface, and the bottom of the hole is connected to the gas source through a gas passage. In order to ensure that the groove ring can form a negative pressure, the height of each ceramic ring 1 should be consistent, so that the wafer surface can be adsorbed between adjacent vacuum ring grooves 2.

[0038] In some embodiments, the vacuum suction holes 21 located in different vacuum ring grooves 2 are also linearly distributed, and the center of the diameter of the linearly distributed vacuum suction holes 21 is collinear with the center of the disk surface. In Figure 8, each vacuum ring groove 2 contains at least one vacuum suction hole 21. Of course, in order to improve the adsorption effect and adsorption uniformity, two or more vacuum suction holes 21 can be symmetrically arranged, similar to a cross-shaped distribution or other forms.

[0039] To ensure clear and high-contrast wafer state images, the entire chuck can be designed as a ceramic structure. The substrate of the microporous ceramic chuck is made of alumina, and both the ceramic ring and the chuck surface are hard-anodized and colored black. This creates a striking color contrast between the black ring and surface and the white filling material in the open circular micropores, improving visibility.

[0040] Furthermore, the ceramic disk surface within the vacuum ring groove 2 can be set to black, and honeycomb-shaped micropores can be formed on the inner surface of the groove, as clearly seen in Figure 4. The texture formed by the honeycomb-shaped micropores can improve the recognition effect, especially when it is the same color as the ceramic ring 1. Different sizes corresponding to different target areas can be quickly identified through the texture, and the deviation between the wafer and the target area can be quickly identified. This ceramic structure and surface oxidation treatment design can eliminate electrostatic effects and protect the wafer from damage under mechanical operating conditions.

[0041] In some embodiments, the ceramic suction cup needs to be mounted on the attitude adjustment mechanism. Therefore, mounting holes 4 are provided on the ceramic ring platform 1 of the plate surface, extending inward or outward. The number of mounting holes on each ceramic ring platform 1 is set according to actual needs. This application uses three as an example for illustration. In Figure 4, the mounting holes 4 on different ceramic ring platforms 1 are staggered. That is, on ceramic ring platforms 1 of the same size, the distance between adjacent mounting holes 4 is 120 degrees, while the distance between two adjacent mounting holes 4 of different sizes is 60 degrees. Of course, other angles can be selected, as long as force balance and stability can be achieved.

[0042] Figure 9 is a cross-sectional view at point A in Figure 4. The thickness of the ceramic disc substrate 10 in the cross-section is designed to be 20mm, and the depth of the groove should not exceed 20mm. In particular, because a honeycomb microporous texture is also set in the groove, this texture also needs to occupy a certain thickness. It is just necessary to maintain the overall proportional balance during the design.

[0043] Figure 10 is a cross-sectional view at point B in Figure 8. The structure of the vacuum suction hole 21 adopts a through-hole design to connect to the lower gas path, and the hole diameter is designed to be 5mm. The center distance between two vacuum suction holes in adjacent vacuum ring grooves does not exceed 27mm. In addition, the vacuum suction hole 21 is opened on the basis of honeycomb micropores. Therefore, based on the vacuum ring groove 2 in Figure 10, the depth of the honeycomb micropores is designed to be 1mm to form a clear texture.

[0044] In summary, this application uses a ceramic-structured chuck as a wafer stage, with ceramic ring stages of different inner diameters on the stage surface to support wafers of various sizes. Vacuum grooves are formed between all the ceramic ring stages, and vacuum suction holes within these grooves create negative pressure, fixing the wafer to the stage surface. The linear micro-holes on the ceramic ring stages consist of several circular micro-holes filled with a filler of a different color from the ceramic substrate, creating high contrast. Using circular micro-holes instead of scribing or grooving avoids the problem of uneven image correction accuracy under high-precision pixel density. The straight lines simulated by connecting the centers of the circles further improve accuracy. Combined with high-color-difference particle filling and non-linear openings, the image of the soft layer is smaller, and the identification of multiple particles to determine straight lines is more accurate.

[0045] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A microporous ceramic suction cup, characterized in that, The microporous ceramic suction cup is circular, with several ceramic rings of different diameters distributed on the surface of the cup, and the ceramic rings of different diameters are arranged with the circular surface of the cup as a common center. A vacuum ring groove is formed between adjacent ceramic ring stages, and a vacuum suction hole is provided in the vacuum ring groove to adsorb the wafer supported by the ceramic ring stage. Linear micropores composed of several circular micropores are formed on different ceramic rings, and the centers of the micropores are collinear; the centers of the micropores on different ceramic rings are collinear with the center of the disk surface; at least two sets of linear micropore arrays with different directions and collinear with the center of the disk surface are provided on each ceramic ring for wafer calibration based on the connection line of the centers of the micropores in the linear micropore array.

2. The microporous ceramic suction cup according to claim 1, characterized in that, At least one vacuum suction hole is provided in each of the vacuum ring grooves, and the vacuum suction hole is a circular through hole that penetrates the disk surface, with the bottom of the hole connected to a gas source through a gas passage.

3. The microporous ceramic suction cup according to claim 2, characterized in that, The vacuum suction holes located in different vacuum ring grooves are linearly distributed, and the center of the diameter of the linearly distributed vacuum suction holes is collinear with the center of the disk surface.

4. The microporous ceramic suction cup according to claim 1, characterized in that, The linear micropores on the ceramic ring include at least three circular micropores of the same structural size, and each circular micropore is filled with a white filler.

5. The microporous ceramic suction cup according to claim 4, characterized in that, The substrate of the microporous ceramic suction cup is an alumina matrix, and the ceramic ring and the surface of the cup are hard anodized and treated to be black.

6. The microporous ceramic suction cup according to claim 5, characterized in that, The ceramic disk inside the vacuum ring groove is black and has honeycomb-shaped micropores on its surface.

7. The microporous ceramic suction cup according to any one of claims 1-6, characterized in that, Three ceramic ring platforms are set on the disc surface, with diameters greater than 125mm, 210mm and 320mm respectively.

8. The microporous ceramic suction cup according to claim 4, characterized in that, The diameter of the circular micropores does not exceed 0.5 mm, and the distance between the centers of adjacent circular micropores does not exceed 0.75 mm.

9. The microporous ceramic suction cup according to claim 2, characterized in that, Each of the ceramic rings is also evenly distributed with several mounting holes, and the mounting holes on different ceramic rings are staggered.

10. The microporous ceramic suction cup according to claim 4, characterized in that, The diameter of the circular micropore does not exceed 5 mm, and the distance between the centers of two vacuum suction holes in adjacent vacuum ring grooves does not exceed 27 mm.

Images