Wafer adsorption device

Abstract

The application provides a wafer adsorption device, which comprises a wafer chuck for adsorbing a wafer, wherein an adsorption surface of the wafer chuck is provided with two or more adsorption zones, and the adsorption zones are separated by sealing rings; and the adsorption zones can generate negative pressure to realize partition adsorption of the wafer. The adsorption zones are arranged in a concentric ring shape, sealing grooves are arranged between adjacent adsorption zones, and the sealing rings are arranged in the sealing grooves. The wafer adsorption device processes the adsorption surface of the wafer chuck into a form with multiple independent adsorption zones, can realize fine control of the wafer adsorption process through control of different adsorption zones, ensures partition adsorption of the wafer, improves adsorption stability and ensures flatness of the wafer after adsorption.

Description

Technical Field

[0001] This invention relates to the field of wafer fixing device technology, and more specifically to a wafer adsorption device. Background Technology

[0002] During semiconductor manufacturing, after undergoing multiple process steps, a significant amount of stress inevitably accumulates on the wafer, causing it to warp or deform partially or completely. Therefore, in subsequent operations, if the wafer is not properly secured, excessive local stress can occur, leading to wafer breakage when it exceeds the wafer's tolerance limit.

[0003] In the photolithography process, to ensure the accuracy of the lithographic pattern, the wafer needs to be reliably and flatly fixed. When the wafer is flat or has only slight warping, completing the above fixing process is not a problem; however, when the wafer warping is severe, vacuum leakage will occur between the existing chuck and the wafer, causing the wafer to be unable to be picked up, resulting in wafer rejection and greatly affecting the yield. Summary of the Invention

[0004] To address the problem that existing wafer adsorption devices cannot be used to adsorb and fix wafers with significant warpage, this invention provides a wafer adsorption device.

[0005] The present invention provides a wafer adsorption device, including a wafer chuck for adsorbing wafers. The adsorption surface of the wafer chuck is provided with two or more adsorption areas, which are separated by a sealing ring. The adsorption areas can generate negative pressure to achieve partitioned adsorption of the wafer.

[0006] Preferably, the adsorption zones are arranged in a concentric ring, and a sealing groove is formed between adjacent adsorption zones, with a sealing ring disposed in the sealing groove.

[0007] Preferably, the adsorption zone is provided with a gas trough for generating negative pressure within the adsorption zone, and the gas troughs located in the same adsorption zone are connected to the same set of gas pipelines.

[0008] Preferably, the gas groove is an annular groove concentric with the adsorption zone, and at least one gas groove is provided in each adsorption zone.

[0009] Preferably, the number of gas slots in the adsorption zone increases in order from the inside to the outside of the adsorption zone.

[0010] Preferably, the sealing ring is installed in a ring shape in the sealing groove. The sealing ring includes a relatively large mounting part disposed inside the sealing groove, and a trumpet-shaped thin-walled skirt extends from the mounting part toward the surface of the wafer chuck.

[0011] Preferably, the skirt is flared outwards in a trumpet shape, so that it can be completely contained within the sealing groove when folded under pressure.

[0012] Preferably, the height of the plurality of sealing grooves decreases sequentially from the outside to the inside.

[0013] Preferably, it further includes a push rod that penetrates the wafer chuck, the push rod being movable within the wafer chuck, and a suction nozzle being provided at one end of the push rod extending out of the adsorption area.

[0014] Preferably, the wafer chuck has a through hole in the adsorption area for the push rod to pass through, the push rod passes through the through hole, and the through hole is sealed when moving between the air groove.

[0015] The wafer adsorption device of the present invention treats the adsorption surface of the wafer chuck as having multiple independent adsorption zones, enabling precise control of the wafer adsorption process by controlling different adsorption zones. Regardless of whether the wafer has significant warpage, the sealing of each adsorption zone and its adsorption of the wafer can always be guaranteed during the adsorption process, thereby achieving zoned adsorption of the wafer, improving adsorption stability, and ensuring the flatness of the wafer after adsorption. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the wafer adsorption device of the present invention;

[0017] Figure 2 This is a cross-sectional schematic diagram of the wafer chuck 1 of the present invention;

[0018] Figure 3 This is a partial schematic diagram of the sealing ring 12 of the present invention;

[0019] Figure 4 This is a side view schematic diagram of the wafer adsorption device of the present invention.

[0020] In the picture,

[0021] 1: Wafer chuck 2: Push rod 11: Adsorption area 12: Sealing ring 13: Sealing groove 14: Gas pipeline 21: Nozzle 22: Lifting cylinder 111: Gas groove 112: Through hole 121: Mounting part 122: Skirt 11A: First adsorption area 11B: Second adsorption area 11C: Third adsorption area 12A: First sealing ring 12B: Second sealing ring 12C: Third sealing ring Detailed Implementation

[0022] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual dimensions. They are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numeral represent similar or identical structures and are limited to illustrative purposes.

[0023] The wafer adsorption device of the present invention includes a wafer chuck 1 for adsorbing wafers. Figure 1This is a schematic diagram of the wafer chuck 1. The wafer chuck 1 uses one side surface to adsorb the wafer for fixation and positioning during wafer photolithography. To achieve stable wafer adsorption, the wafer chuck 1 has multiple independently controlled adsorption areas 11, separated by sealing rings 12. Each adsorption area 11 is connected to an independent gas pipeline 14 (due to the cross-sectional orientation, not all gas pipelines connected to each adsorption area 11 are shown in the figure), so their gas pressure control is independent and does not affect each other. When adsorbing and fixing the wafer, the sealing ring 12 is attached to the lower surface of the wafer, thereby isolating the different adsorption areas 11 from each other during operation.

[0024] Figure 2 This is a cross-sectional view of the wafer chuck 1. The adsorption regions 11 are arranged in a concentric ring, and the figure shows a structure with three adsorption regions 11. From the inside out, they are the first adsorption region 11A, the second adsorption region 11B, and the third adsorption region 11C. The first adsorption region 11A is the innermost circular area, which in this application is equivalent to a ring with an inner diameter of zero, and is therefore referred to as a concentric ring structure. The adsorption regions 11 are separated by sealing rings 12. Each adsorption region 11 is provided with a gas groove 111 for generating negative pressure within the adsorption region 11, and the gas grooves 111 located in the same adsorption region 11 are connected to the same set of gas pipelines. Different adsorption regions 11 can be connected to a unified negative pressure generating pipeline, or they can be connected to independently controlled negative pressure generating pipelines to independently control the generation and release of their negative pressure. A sealing groove 13 is provided at the connection of the adsorption regions 11 to accommodate the sealing ring 12. The sealing ring 12 is disposed in the sealing groove 13 and has a skirt extending towards the surface of the wafer chuck 1.

[0025] The gas groove 111 should be continuous around the adsorption area 11, preferably forming an annular groove concentric with the adsorption area 11. At least one gas groove 111 is provided in each adsorption area 11. Preferably, the number of gas grooves 111 in each adsorption area 11 increases from the inside out. For example, in the figure, the first adsorption area 11A has only one gas groove 111, the second sealing ring 12B has two gas grooves 111, and the third sealing ring 12C has seven gas grooves 111. The increasing number of gas grooves 111 ensures, or even improves, the distribution of gas grooves per unit area from the inside out, ensuring sufficient negative pressure channels to generate negative pressure for wafer adsorption. After the wafer is placed on the surface of the wafer chuck 1, the sealing ring 12 contacts the wafer surface, isolating the adsorption areas 11. By controlling different gas pipelines, the gas grooves 111 in different adsorption areas 11 generate negative pressure to adsorb the wafer onto the surface of the wafer chuck 1.

[0026] Figure 3This is a schematic diagram of the arrangement of the sealing ring 12 in the above embodiment of the wafer adsorption device. The sealing ring 12 is annular and installed in the sealing groove 13, as shown in the figure. It includes a relatively wide mounting portion 121 to fix and maintain its installation direction within the sealing groove 13, so as to prevent the mounting portion 121 from tilting or shifting after the sealing ring 12 is subjected to force. A trumpet-shaped thin-walled skirt 122 extends from the mounting portion 121 toward the surface of the wafer chuck 1. The skirt 122 is flared outwards so that when a negative pressure is generated in the adsorption area 11, it collapses and folds into the sealing groove 13 in the direction of the already formed tilt angle until the skirt 122 is completely contained in the sealing groove 13. The advantage is that this can prevent the skirt 122 from being mistakenly pressed between the surface of the adsorption area 11 and the lower surface of the wafer, which will not only affect the flatness of the wafer, but also cause severe local deformation and excessive stress on the wafer, leading to its breakage. In a preferred embodiment, such as Figure 3 As shown, the height of the skirt 122 above the surface of the wafer chuck 1 varies, decreasing with the diameter of the sealing ring 12. This means that the skirt 122 forms a concave portion with a slightly higher outer ring and a slightly lower inner ring, where a warped chip may be supported. In existing solutions, warped chips are unstable when placed on the wafer chuck 1, causing wobbling and potentially leading to poor adsorption and misalignment during adsorption. In this solution, the combination of the concave skirt 122 and the co-directionally warped chip effectively prevents positional shifts before adsorption and helps balance the gaps between different skirts 122 and the bottom surface of the chip during adsorption, achieving uniform and stable chip adsorption. Under this scheme, in practical application, based on the statistical analysis of chip warping deformation, in the non-adhesive state, the skirt of the third sealing ring 12C is designed to be 2.0mm higher than the surface of the wafer chuck 1, the skirt of the second sealing ring 12B is 1.65mm higher than the surface of the wafer chuck 1, and the skirt of the first sealing ring 12A is 1.2mm higher than the surface of the wafer chuck 1, which can achieve a good adsorption effect.

[0027] like Figure 2As shown, due to the previous processing steps, the wafer itself may have significant warpage. Even if the wafer is accurately placed on the wafer chuck 1, there is still a large gap between the outer periphery of the wafer and the adsorption surface of the wafer chuck 1. This gap means that when negative pressure is applied to the adsorption surface of the wafer chuck 1, the gap between the wafer and the adsorption surface is insufficient to press the wafer down to seal it with the adsorption surface or the sealing ring on the adsorption surface. Therefore, wafers with significant warpage may be rejected. In addition, since integral adsorption cannot guarantee that all parts of the wafer are uniformly adsorbed onto the surface of the wafer chuck 1, it is difficult to guarantee the flatness of the wafer after adsorption. If a larger negative pressure is created in the air groove 111 to enhance the adsorption effect of the adsorption area 11 on the wafer and ensure the flatness of the wafer, the potential problem is that the large negative pressure area makes it difficult to ensure uniform force during adsorption, and the warpage of the wafer will exacerbate this problem. Therefore, due to uneven force, wafers with more severe deformation may break during the adsorption process.

[0028] During the adsorption process of this wafer adsorption device, after the wafer is placed on the adsorption surface of the wafer chuck 1, due to the wafer's warping, its center is closer to the adsorption surface of the wafer chuck 1 while its outer edges are farther away. Therefore, the first sealing ring 12A is closer to the wafer, or has already contacted the wafer to form support. After creating negative pressure in the first adsorption area 11A, the second adsorption area 11B, and the third adsorption area 11C, the first sealing ring 12A first adsorbs and seals the wafer in the first adsorption area 11A. Under the negative pressure of the third adsorption area 11C, the wafer is adsorbed and moved towards the surface of the wafer chuck 1, correcting the wafer's warping. Then, after the second sealing ring 12B contacts the wafer, the first sealing ring 12A and the second sealing ring 12B form a seal, allowing the wafer to continue moving and bringing its surface into contact with the third sealing ring 12C. Finally, with the combined adsorption of the first adsorption area 11A, the second adsorption area 11B, and the third adsorption area 11C, the wafer is ensured to be uniformly adsorbed onto the surface of the wafer chuck 1. Even when negative pressure is simultaneously applied to the first adsorption region 11A, the second adsorption region 11B, and the third adsorption region 11C, due to the wafer warping causing differences in the radial gap between the wafer and the wafer chuck 1, there is still a slight time difference in the above process, ensuring stable wafer adsorption. Alternatively, the order of negative pressure application to the first adsorption region 11A, the second adsorption region 11B, and the third adsorption region 11C can be sequentially delayed to better control the adsorption process, ensure adsorption stability, and avoid wafer breakage caused by excessive mechanical stress during adsorption, especially for wafers with severe warping.

[0029] Because the adsorption area of ​​the third adsorption region 11C is small and close to the center of the wafer, and the gap between the third sealing ring 12C and the wafer is small (or in complete contact), the adsorption and fixation of the wafer can be ensured, preventing wafer rejection. With the use of the first sealing ring 12A, the second sealing ring 12B, and the third sealing ring 12C, regardless of whether the wafer has significant warpage, the skirt of the sealing ring 12 is higher than the surface of the wafer chuck 1, ensuring the sealing of each adsorption region 11 and its adsorption of the wafer during the adsorption process. This achieves zoned adsorption of the wafer, and the stable negative pressure at each point in each adsorption region 11 ensures uniform force on the wafer, preventing wafer breakage and ensuring the flatness of the wafer after adsorption. At least one gas groove is present in the first adsorption region 11A, the second adsorption region 11B, and the third adsorption region 11C and is connected around the adsorption region 11. This means that due to the presence of the gas groove 111, the gas pressure is consistent in all circumferential directions within the adsorption region 11. The problem of inconsistent pressure at various points in the initial adsorption stage due to the lack of connection between holes on the surface of the wafer chuck 1 after wafer adsorption will not occur under the point-like negative pressure holes. Therefore, it can ensure that the wafer is corrected as expected and uniformly attached to the wafer chuck 1, and reduce the mechanical stress in the wafer.

[0030] The wafer adsorption device also includes a push rod 2 that penetrates the wafer chuck 1. The push rod 2 is movable within the wafer chuck 1, and is relatively sealed to the wafer chuck 1 during movement. Specifically, the wafer chuck 1 has a through hole 112 in the first adsorption area 11A for the push rod 2 to pass through. The push rod 2 protrudes from the through hole 112, and a sealing gasket ensures that the first adsorption area 11A remains sealed during movement within the through hole 112. A suction nozzle 21 is provided at one end of the push rod 2 extending out of the adsorption area 11. Three push rods 2 are provided within the adsorption area 11, which can be evenly distributed around the center of the adsorption area 11. The other end of the push rod 2 is connected to a negative pressure source, which is internally connected to the suction nozzle 21. All the push rods 2 are driven by a lifting cylinder 22 to move within the through hole 112.

[0031] During the operation of the wafer adsorption device, the lifting cylinder 22 first drives the lifting rod 2 to rise to a certain height away from the adsorption surface of the wafer chuck 1. Then, the robotic arm and other conveying components place the wafer above the lifting rod 2, which lifts and temporarily adsorbs the wafer. After the lifting rod 2 descends into the through hole 112, the wafer falls onto the adsorption surface of the wafer chuck 1 and is supported by the sealing ring 12. The negative pressure generated in the adsorption area 11 adsorbs and adheres the wafer to the adsorption surface of the wafer chuck 1. In this operation, the robotic arm only needs to place the wafer on the lifting rod 2. Since the robotic arm holds the wafer on both sides, the lifting of the lifting rod 2 not only provides space for the robotic arm to move below the lifting rod 2, allowing the robotic arm to place the wafer smoothly and accurately on the lifting rod 2 and temporarily adsorb it by the suction nozzle 21, but also ensures that the robotic arm does not come into contact with the wafer chuck 1 or the sealing ring 12 on it, avoiding scratches to the sealing ring 12.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A wafer adsorption device, characterized in that, Includes a wafer chuck (1) for adsorbing wafers, and the wafer chuck (1) has two or more adsorption areas (11) on its adsorption surface, which are separated by a sealing ring (12); the adsorption areas (11) can generate negative pressure to achieve partitioned adsorption of the wafer; The adsorption zones (11) are arranged in a concentric ring, and a sealing groove (13) is provided between adjacent adsorption zones (11), with a sealing ring (12) disposed in the sealing groove (13). The wafer chuck (1) has a structure with three adsorption regions (11), which are the first adsorption region (11A), the second adsorption region (11B) and the third adsorption region (11C) from the inside out, forming a concentric ring structure. The negative pressure connection sequence between the first adsorption zone (11A), the second adsorption zone (11B), and the third adsorption zone (11C) is sequentially delayed; The sealing ring (12) is installed in the sealing groove (13) in a ring shape. The sealing ring (12) includes a relatively large mounting part (121) disposed inside the sealing groove (13). The sealing ring (12) has a trumpet-shaped thin-walled skirt (122) extending from the mounting part (121) toward the surface of the wafer chuck (1). The height of the sealing rings (12) decreases from the outside to the inside. In the non-adsorbed state, the skirt of the third sealing ring (12C) is designed to be 2.0 mm higher than the surface of the wafer chuck (1), the skirt of the second sealing ring (12B) is 1.65 mm higher than the surface of the wafer chuck (1), and the skirt of the first sealing ring (12A) is 1.2 mm higher than the surface of the wafer chuck (1). As the diameter of the sealing ring (12) decreases, the height of the skirt (122) above the wafer chuck (1) decreases, and the skirt (122) forms a concave portion with a slightly higher outer ring and a slightly lower inner ring, on which a warped chip is supported. The adsorption zone (11) is provided with a gas trough (111) for generating negative pressure in the adsorption zone (11), and the gas troughs (111) located in the same adsorption zone (11) are connected to the same set of gas pipelines. The gas groove (111) is an annular groove concentric with the adsorption zone (11), and at least one gas groove (111) is provided in each adsorption zone (11); The number of gas grooves (111) in the adsorption zone (11) increases from the inside to the outside of the adsorption zone (11); Each adsorption zone (11) is connected to an independent gas pipeline (14).

2. The wafer adsorption device as described in claim 1, characterized in that, The skirt (122) is flared outwards in the shape of a trumpet and can be completely contained in the sealing groove (13) when it is folded under pressure.

3. The wafer adsorption device as described in claim 1, characterized in that, It also includes a push rod (2) that runs through the wafer chuck (1), the push rod (2) being movable within the wafer chuck (1), and a suction nozzle (21) being provided at one end of the push rod (2) extending out of the adsorption area (11).

4. The wafer adsorption device as described in claim 3, characterized in that, The wafer chuck (1) has a through hole (112) in the adsorption area (11) for the push rod (2) to pass through. The push rod (2) passes through the through hole (112) and moves and seals with the air groove (111).

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