Wafer warpage correction device

Abstract

The utility model provides a kind of wafer warping straightening device, including wafer carrier, and the surface of wafer carrier towards wafer side is equipped with center area, inner ring area and outer ring area sequentially arranged from inside to outside and can be separately heated to form temperature gradient;With wafer carrier opposite arrangement and provide the pressure of wafer to wafer carrier by driving device as wafer lower pressure assembly;Array is set on the opposite surface of wafer carrier and lower pressure assembly pressure sensor;Pressure sensor is used to transmit the electrical signal information of the area where it is located and wafer warping portion abuts;The contact surface between wafer carrier and wafer is divided into sequentially ringed center area, inner ring area and outer ring area, and the electrical signal of wafer warping portion and wafer carrier or lower pressure assembly contact transmitted by pressure sensor realizes positioning, so that whole wafer can realize heating of partition accuracy, also avoid the uneven heat distribution of wave warping portion when heating in whole domain, cause the situation of different expansion coefficients.

Description

Technical Field

[0001] This utility model relates to the technical field of wafer processing and manufacturing, and in particular to a wafer warpage straightening device. Background Technology

[0002] Warping and deformation of wafers during the manufacturing process due to thermal stress, uneven thin film deposition, or mechanical stress directly limits wafer yield. Therefore, leveling has become an essential technology to ensure high yield.

[0003] For example, Chinese invention patent document CN118748160A, entitled "A Multilayer Wafer Warpage Leveling Device," discloses that "the fixing frame, lifting frame, upper flattening plate 6, and lower flattening plate 5 of the multilayer wafer warpage leveling device can all be installed in the baking area of ​​the baking oven. The base frame 1 and the positioning pin sleeve 24 are installed in the insulation layer of the baking oven, and the linear drive device 21 and the substrate 22 are located in the lower space of the baking oven. In order to improve the sealing performance, a sealing structure can be provided between the two ends of the positioning pin sleeve 24 and the positioning pin 23. The positioning pin sleeve 24 is connected to the base frame 1 through a shaft seal clamping seat."

[0004] However, the above technical solutions have revealed the following defects in practical applications: 1) The wafer leveling device uses full-area synchronous heating, and its heat energy is easily absorbed by the cavity wall or lost with the airflow, resulting in serious heat loss. 2) The wafer has asymmetric warp, and non-contact heating cannot accurately distribute the temperature over the entire area, and cannot avoid the local temperature difference caused by the wavy warp of the wafer; 3) When heating thin wafers, if the local temperature is too high, the warped part may warp again due to uneven thermal expansion, causing thermal stress concentration and eventually leading to wafer breakage.

[0005] Accordingly, this application provides a warped wafer leveling device that can achieve gradient heating, precise softening, and sequential release of internal wafer stress. Utility Model Content

[0006] In view of the shortcomings of the prior art described above, the purpose of this utility model is to provide a wafer warpage straightening device, which uses pressure sensors arranged in an array on the wafer stage and the pressing component, in conjunction with an arc-shaped heating strip housed in an annular groove, to achieve gradient heating, precisely soften the wafer, and sequentially release the internal stress of the warped wafer.

[0007] To achieve the above and other related objectives, this utility model provides the following technical solution: A wafer warpage leveling device includes a wafer stage for supporting a wafer. The wafer stage has a central region, an inner ring region, and an outer ring region arranged sequentially from the inside to the outside and can be individually heated to form a temperature gradient on the wafer-facing side surface. A pressure-down assembly that is positioned opposite to the wafer stage and provides downward pressure to the wafer via a drive device; An array of pressure sensors is located on the opposite surfaces of the wafer stage and the pressure assembly; the pressure sensors are used to transmit electrical signal information about the contact between their location and the warped portion of the wafer.

[0008] To achieve the above technical solution, the contact surface between the wafer stage and the wafer is divided into a central area, an inner ring area, and an outer ring area arranged in sequence. The positioning is achieved by the electrical signal transmitted by the pressure sensor that the warped part of the wafer contacts the wafer stage or the pressing component. This allows the entire wafer to achieve precise heating in different zones, while avoiding the uneven heat distribution in the warped part that causes different expansion coefficients when heating the entire area.

[0009] Furthermore, several annular grooves are formed on the side of the wafer stage facing the wafer.

[0010] To achieve the above technical solution, the surface of the wafer stage facing the wafer is roughly divided into a central area, an inner ring area, and an outer ring area according to the diameter of the annular trench. Based on the division of the above areas, the pressure sensor is configured as a first pressure sensor, a second pressure sensor, and a third pressure sensor to achieve precise positioning of the warped portion of the wafer.

[0011] Furthermore, a cross-shaped flow channel is formed on the wafer carrier, which divides the annular groove and forms several fan-shaped heating zones in the central area, inner ring area and outer ring area respectively.

[0012] To achieve the above technical solution, the design of the flow channel allows the gas in the cavity formed between the warped part of the wafer and the wafer stage to be discharged regardless of the shape of the wafer warping, thus avoiding stress residue in the wafer.

[0013] Furthermore, an arc-shaped heating strip is provided inside the annular groove.

[0014] To achieve the above technical solution, the arc-shaped heating strips are set in the annular grooves of their respective fan-shaped heating zones. The electrical signal transmitted by the pressure sensor determines whether to heat the area and simultaneously heats the surrounding area, ensuring that the temperature difference between the two is kept within 20°C. The temperature gradient is gradually reduced around the warped part that contacts the sensor area, in order to eliminate local overheating or excessive temperature difference and reduce the risk of secondary wafer warping due to uneven stress relief.

[0015] Furthermore, the side of the pressing component facing the wafer stage is a flexible layer.

[0016] The above technical solution can be achieved by setting a flexible layer, which can effectively avoid wafer damage caused by the impact of the pressing component on the wafer during the pressing process.

[0017] Furthermore, the wafer stage is also provided with a height-adjustable limiting post on the side facing the pressing component, which is used to abut against the pressing component.

[0018] To achieve the above technical solution, the limiting post abuts against the pressing component, and a receiving space that can accommodate the wafer is formed between the wafer stage and the pressing component. Moreover, the height of the limiting post is adjustable, and the limiting post can be adjusted according to the thickness of the wafer to meet the correction requirements of wafers of different thicknesses, thereby improving the applicability of the device.

[0019] Furthermore, it also includes a control unit, which is electrically connected to the pressure sensor, the arc-shaped heating strip, and the drive device.

[0020] To achieve the above technical solution, the interactive terminal in the control unit allows technicians to set the heating temperature of the annular heating strip, control the descent speed of the drive device, and display the electrical signal transmitted by the pressure sensor, converting it into specific values ​​for technicians to observe.

[0021] As described above, the wafer warpage straightening device of this invention has the following beneficial effects: 1. In this application, the arc-shaped heating strips are respectively set in the annular grooves in their respective fan-shaped heating areas. The electrical signal transmitted by the pressure sensor determines whether to heat the area and simultaneously heats the surrounding area, ensuring that the temperature difference between the two is kept within ℃. The arc-shaped heating strips form an annular temperature gradient with the warped part as the center, which gradually decreases around it, in order to eliminate local overheating or excessive temperature difference and reduce the risk of secondary warping of the wafer due to uneven stress relief.

[0022] 2. In this application, the limiting post abuts against the pressing component and forms a receiving space between the wafer stage and the pressing component that can accommodate the wafer. The height of the limiting post is adjustable, and the limiting post can be adjusted according to the thickness of the wafer to meet the correction requirements of wafers of different thicknesses and improve the applicability of the device. Attached Figure Description

[0023] Figure 1 The diagram shown is a structural schematic of a wafer warpage straightening device according to this utility model.

[0024] Figure 2 The diagram shown is a schematic representation of the wafer carrier in this invention.

[0025] The components include: 1. Wafer stage; 11. Central area; 12. Inner ring area; 13. Outer ring area; 14. Annular trench; 15. Guide channel; 16. Limiting post; 17. Fan-shaped heating area; 2. Pressing assembly; 21. Flexible layer; 3. Pressure sensor; 31. First pressure sensor; 32. Second pressure sensor; 33. Third pressure sensor; 4. Control unit; 5. Drive device. Detailed Implementation

[0026] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0027] Please see Figure 1-2 It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this invention, should still fall within the scope of the disclosed technical content. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0028] Please see Figures 1 to 2 This invention provides a wafer warpage leveling device, including a wafer stage 1 and a pressing component 2 arranged opposite to each other. The pressing component 2 is positioned towards the wafer stage 1 and is driven by a driving device 5 to move closer to or away from the wafer stage 1. The wafer is placed on the wafer stage 1, and the pressing component 2 provides downward pressure to the wafer towards the wafer stage 1. The driving device 5 is fixedly mounted on a mounting frame (not shown in the figure), and the pressing component 2 is mounted on the mounting frame via the driving device 5 and is positioned towards the wafer stage 1.

[0029] Among them, several pressure sensors 3 are arranged in an array on the opposite surfaces of the wafer stage 1 and the pressing component 2. When the pressing component 2 approaches the wafer stage 1 and provides pressure to the wafer, the pressure sensors 3 are used to transmit electrical signals of their area contacting the warped portion of the wafer.

[0030] Preferably, the pressure sensors 3 on the opposing surfaces of the wafer stage 1 and the pressing component 2 are staggered to cover as much area as possible on both sides of the wafer, so as to mutually compensate for the positioning of the warped portions on both sides of the wafer.

[0031] Please continue reading. Figure 2 The wafer stage 1 has annular grooves 14 of different diameters, which, according to their diameters, roughly form a central region 11, an inner ring region 12, and an outer ring region 13. An arc-shaped heating strip (not shown) is provided within the annular grooves 14 for heating the warped portion of the wafer. The contact surface between the wafer stage 1 and the wafer is divided into a central region 11, an inner ring region 12, and an outer ring region 13 arranged in sequence. Positioning is achieved through an electrical signal transmitted by the pressure sensor 3 indicating contact between the warped portion of the wafer and the wafer stage 1 or the pressing assembly 2. This allows for precise heating of the entire wafer in designated areas, while avoiding uneven heat distribution and inconsistent expansion coefficients in the warped portion during full-area heating.

[0032] Based on the above division of the central area 11, the inner ring area 12 and the outer ring area 13, the pressure sensor 3 is configured as a first pressure sensor 31, a second pressure sensor 32 and a third pressure sensor 33.

[0033] The top surface of the pressure sensor 3 is flush with the contact surface between the wafer stage 1 and the wafer. It is used to determine whether the warped portion of the wafer is in contact with the wafer stage 1 or the pressing assembly 2, and transmits an electrical signal indicating the area in contact with the wafer. When the value of the electrical signal transmitted by the pressure sensor 3 is not zero, it means that the area of ​​the pressure sensor 3 is in contact with the warped portion of the wafer. When the value of the electrical signal transmitted by the pressure sensor 3 gradually decreases to zero, the warped portion of the wafer in contact with the area of ​​the pressure sensor 3 is straightened. When the value of the electrical signal transmitted by the pressure sensor 3 remains zero, the wafer portion corresponding to the area of ​​the pressure sensor 3 is warped to the other side or has not warped.

[0034] It should be noted that this application does not limit the number of sensors. Provided that the contact between the wafer and the wafer stage 1 or the pressing assembly 2 is monitored, a corresponding number of pressure sensors 3 can be installed on the wafer stage 1 and the pressing assembly 2. Preferably, the pressure sensor 3 is a column-type pressure-sensitive sensor.

[0035] Please refer to section 2. Several sets of cross-shaped drainage channels 15 are formed on the wafer stage 1. The drainage channels 15 "divide" the annular groove 14 radially along the wafer stage 1. Regardless of the shape of the wafer warpage, the drainage channels 15 can discharge the gas in the cavity formed between the warped part of the wafer and the wafer stage 1, avoiding stress residue in the wafer.

[0036] In this embodiment, the guide groove 15 is set in two groups, which divide the central area 11, the inner ring area 12 and the outer ring area 13 into several independent fan-shaped heating areas 17.

[0037] It should be noted that each sector heating zone 17 is ensured to contain at least one pressure sensor 3. The wafer stage 1 is "divided" into 24 sector heating zones 17 by the arrangement of the guide grooves 15. Each sector heating zone 17 contains at least one pressure sensor 3, and each pressure sensor 3 is used to reflect the contact status between the area and the warped portion of the wafer.

[0038] Similarly, the arc-shaped heating strips are respectively set in the annular grooves 14 within the fan-shaped heating areas 17. The electrical signal transmitted by the pressure sensor 3 determines whether to heat that area, and simultaneously heats the surrounding area, ensuring the temperature difference between them remains within 20°C. Roughly centered on the warped portion, a gradually decreasing annular temperature gradient is formed around it to eliminate localized overheating or excessive temperature differences, reducing the risk of secondary wafer warping due to uneven stress relief. Furthermore, the heating strips are completely contained within the annular grooves 14, meaning their maximum height after installation does not exceed the contact surface between the wafer stage 1 and the wafer. Simultaneously, precise heating of the warped wafer avoids significant heat loss during full-area heating, reducing heat energy loss and saving production costs.

[0039] Please continue reading. Figure 1 The side of the pressing component 2 facing the wafer stage 1 is a flexible layer 21, and the pressure sensor 3 is disposed on the side of the flexible layer 21 facing the wafer. The flexible layer 21 is made of a high-temperature resistant material. The flexible layer 21 can effectively prevent wafer damage caused by impacts during the pressing process of the pressing component 2.

[0040] Preferably, the flexible layer 21 is also provided with a flow guide groove 15 and an arc-shaped heating strip, both of which serve the same function as above and will not be described again here. The same flow guide groove 15 and arc-shaped heating strip as those on the wafer stage 1 are provided on the pressing assembly 2 to form a fan-shaped heating area 17 on the flexible layer 21 of the pressing assembly 2 that corresponds to that on the wafer stage 1. This can both heat and compensate for the warped portion protruding towards the pressing assembly 2 and accelerate the efficiency of wafer leveling.

[0041] Please continue reading. Figure 2 The wafer stage 1 is also provided with a height-adjustable limiting post 16 on the side facing the pressing component 2. The difference between the setting height of the limiting post 16 and the standard thickness of the wafer is less than 2mm.

[0042] The limiting post 16 abuts against the pressing component 2 and forms a receiving space between the wafer stage 1 and the pressing component 2 that can accommodate the wafer. The height of the limiting post 16 is adjustable, and the limiting post 16 can be adjusted according to the thickness of the wafer to meet the correction requirements of wafers of different thicknesses and improve the applicability of the device.

[0043] Please continue reading. Figure 1 It also includes a control unit 4, which is electrically connected to the pressure sensor 3, the arc-shaped heating strip, and the drive device 5.

[0044] The control unit 4 includes a built-in programmable controller and an interactive terminal. The interactive terminal allows technicians to set the heating temperature of the annular heating strip, control the descent speed of the drive device 5, and display the electrical signal transmitted by the pressure sensor 3, converting it into specific values ​​for technicians to observe.

[0045] In addition, the wafer stage 1 is equipped with several temperature sensors, which are electrically connected to the control unit 4 and distributed in each sector heating area 17. The temperature of the sector heating area 17 is monitored by the sensors, and the arc heating strip is controlled by the control unit 4 to achieve temperature controllability of each sector heating area 17, providing a stable temperature environment for the softening and leveling of the wafer.

[0046] The implementation principle of the wafer warpage straightening device provided by this utility model is as follows: When the technician places the warped wafer on the wafer stage 1, the control unit 4 activates the drive device 5. Under the drive of the drive device 5, the pressing component 2 moves toward the wafer according to the parameters set by the interactive terminal and presses the wafer toward the wafer stage 1. After the pressing component 2 comes into contact with the wafer, the warped part of the wafer will first contact the wafer stage 1 or the pressing component 2. The pressure sensor 3 set on the wafer stage 1 and the pressing component 2 will transmit an electrical signal to the control unit 4 after being pressed. The control unit 4 first sends a stop electrical signal to the drive device 5 to prevent the pressing component 2 from damaging the wafer. Subsequently, according to the electrical signal transmitted by the pressure sensor 3 (e.g., the second pressure sensor 32 in the third fan-shaped heating area 17 of the inner ring area 12), the control unit 4 activates the arc-shaped heating strip in that area (e.g., heating to 180°) and simultaneously opens the arc-shaped heating strip surrounding and adjacent to that area, and maintains the temperature of that area at 1°C. At 60°C, the temperature of the outermost surrounding area is stabilized at 140°C, ensuring that the temperature difference between the heated warped portion and other parts of the wafer is not too large, thus avoiding local overheating and uneven thermal expansion coefficients that could lead to secondary warping. (If multiple pressure sensors 3 send electrical signals to the control unit 4, these areas are prioritized as being in contact with the warped portion of the wafer, heated to a preset 180°C, and the temperature gradient is redefined; if the number of pressure sensors 3 displaying pressure values ​​is ≥50%, all annular heating bars are activated.) As the warped portion gradually softens, the drive device 5 presses down further, and the interactive terminal of the control unit 4 displays the pressure values ​​transmitted from sensors in other areas. The heating steps are the same as above and will not be repeated. When the values ​​transmitted from the pressure sensors 3 gradually reach zero, and the pressing component 2 abuts against the limiting post 16, the wafer is relatively flattened. The drive device 5 drives the pressing component 2 to rise, and the technician removes the wafer and sends it to the next processing step.

[0047] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A wafer warpage leveling device, characterized in that, include: A wafer stage (1) for supporting a wafer has a central region (11), an inner ring region (12) and an outer ring region (13) arranged sequentially from the inside to the outside and can be heated individually to form a temperature gradient on the wafer-facing side surface. A pressing component (2) is disposed opposite to the wafer stage (1) and provides downward pressure to the wafer via a driving device (5) toward the wafer stage; An array of pressure sensors (3) are arranged on the opposite surfaces of the wafer stage (1) and the pressing assembly (2); the pressure sensors (3) are used to transmit electrical signal information of the area where they are located and the warped portion of the wafer.

2. The wafer warpage leveling device according to claim 1, characterized in that, The wafer stage (1) has several annular grooves (14) on the side facing the wafer.

3. The wafer warpage leveling device according to claim 2, characterized in that, The wafer stage (1) has a cross-shaped guide groove (15) that divides the annular groove (14) and forms several fan-shaped heating areas (17) in the central area (11), inner ring area (12) and outer ring area (13) respectively.

4. The wafer warpage straightening device according to claim 3, characterized in that, The annular groove (14) is provided with an arc-shaped heating strip.

5. The wafer warpage straightening device according to claim 1, characterized in that, The side of the pressing component (2) facing the wafer stage (1) is a flexible layer (21).

6. The wafer warpage leveling device according to claim 1, characterized in that, The wafer stage (1) is also provided with a height-adjustable limiting post (16) on the side facing the pressing component (2) to abut against the pressing component.

7. The wafer warpage leveling device according to claim 1, characterized in that, It also includes a control unit (4), which is electrically connected to the pressure sensor (3), the arc heating strip (151) and the drive device (5).

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