Wafer cooling chuck

Abstract

The present invention discloses a wafer cooling chuck, comprising a circular chuck body having an air inlet at the center thereof, a focusing ring disposed near the center thereof, six equiangularly spaced partition walls extending from the outer wall of the focusing ring, dividing the chuck body into six partition zones, the partition walls extending to the edge of the chuck body, a flow guide hole disposed on the focusing ring between two adjacent partition walls, at least one ejector pin hole disposed on the chuck body in each of three non-adjacent partition zones, and vacuum suction cups disposed on the chuck bodies in the remaining three partition zones, the vacuum suction cups being connected to the same vacuum pump. The design of the invention allows wafers to be received / transported by the vertical movement of the ejector pins, and the wafers to be adsorbed and fixed by the vacuum suction cups. By forming a three-point plane, even deformed wafers can be completely fixed, and the coordination of the partition zones increases the cooling gas flow rate, accelerating the cooling process.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a wafer cooling chuck. Background Art

[0002] Wafer-level packaging (WLP) often requires cooling heated wafers to room temperature during the process, such as during EMC high-temperature curing and glue coating steps. Currently, process equipment for such applications mainly cools the wafers by placing them on a cold plate.

[0003] The cold plate cooling method has the following defects:

[0004] 1. The cold plate temperature is typically 18-30 degrees Celsius, while the cleanroom room temperature is typically 23-25 ​​degrees Celsius. To reach 18 degrees Celsius, the cold plate needs to be connected to a freezer, and to 30 degrees, a heater is required, making the system complex and costly. Furthermore, if the cold plate is set to 18 degrees Celsius to speed up cooling, the time it takes for the wafer to cool to room temperature (25 degrees Celsius) must be calculated and strictly adhered to during the cooling process; otherwise, the wafer temperature may fall below room temperature.

[0005] 2. The cold plate temperature is 18-30 degrees Celsius, with a relatively narrow adjustment range. When the cold plate temperature is set higher than room temperature (25-30 degrees Celsius), the wafer temperature at the end of cooling will not reach the standard room temperature. Furthermore, the cold plate temperature cannot change during the wafer cooling process. Therefore, when the process requires different wafer temperature drop curves, the cold plate's narrow adjustment range cannot meet the detailed cooling requirements.

[0006] 3. Wafers in the WLP process will deform due to process reasons during the process, with the maximum deformation reaching ±3mm. When a deformed wafer is placed on a cold plate, part of it will contact the cold plate while part of it will not. During the cooling process, the part of the wafer that contacts the cold plate cools down faster, while the part that does not cool down slower. The different rates of temperature change of the wafer will form different stresses, and the local stress differences may damage the semiconductor devices on the wafer. Summary of the Invention

[0007] Purpose of the invention: The purpose of the present invention is to solve the problem of uneven cooling caused by placing the wafer on a cold plate, which is costly, has an imprecise and insignificant cooling effect, and is prone to deformation of the wafer and incomplete contact with the cold plate.

[0008] Technical solution: To solve the above problems, the present invention adopts the following technical solution:

[0009] A wafer cooling chuck, characterized in that it includes a circular chuck body with an air inlet at the center of the circle, a focusing ring is arranged on the chuck body near the center of the circle, six equiangularly separated partition walls extend from the outer wall of the focusing ring, dividing the chuck body into 6 partition areas, the partition walls extend to the edge of the chuck body, there are guide holes on the focusing ring between two adjacent partition walls, there is at least one pinhole on the chuck body in three non-adjacent partition areas, and there are vacuum suction cups on the chuck bodies of the remaining three partition areas, and the vacuum suction cups are connected to the same vacuum pump.

[0010] The air inlet is directly connected to the air compressor or factory compressed air through a pipe, and can also be connected to the nitrogen pipeline for cooling to room temperature.

[0011] The vertical movement of the three ejector pins in the ejector pin holes can stably receive the wafer delivered after the previous process step and be fixed by three vacuum suction cups. The adsorption of the suction cups can better fix the wafer. Considering that the wafer may deform, a three-point fixing method is adopted, which is obviously more conducive to the uniformity of cooling.

[0012] By arranging a plurality of partition walls and the cooperation of the partition areas, the flow of the cooling gas in the partition areas has the required directionality and at the same time has a certain flow rate, thereby improving the cooling efficiency.

[0013] Furthermore, a needle valve and a shut-off valve are provided on the pipeline outside the chuck for connecting to the vacuum suction cup.

[0014] Since the wafer may be deformed, if the wafer has no deformation or the deformation is relatively small, use the needle valve to lower the vacuum suction volume. At the same time, the suction force of the three vacuum suction cups can also correct the slight deformation of the wafer. If the wafer is severely deformed, increase the vacuum suction volume to ensure stable adsorption.

[0015] Furthermore, the vacuum suction cup includes a funnel-shaped metal suction nozzle extending from the chuck body and a fluororubber suction cup adhered to the inner surface of the metal suction nozzle.

[0016] Make the contact area between the vacuum chuck and the wafer softer.

[0017] Furthermore, a circular support ring is provided on the edge of the chuck body, and the partition wall is connected to the support ring at the end of the edge of the chuck body. The support ring has a plurality of openings that can penetrate to the outside.

[0018] The support ring acts as a bracket.

[0019] Furthermore, the focusing ring, the partition wall and the support ring have the same height.

[0020] Furthermore, a plurality of small contact points are formed on the top of the partition wall, and there is at least one notch on the partition wall for penetrating adjacent partition areas.

[0021] When the wafer adsorbed by the vacuum suction cup is deformed, the wafer may come into contact with the partition wall. The design of small contact points reduces the contact area between the partition wall and the wafer and improves the uniformity of cooling. The notches on the partition wall are to prevent the cooling temperature from being unbalanced due to different cooling gas pressures in each partition area.

[0022] The same partition wall can have multiple notches. The notches on the two partition walls in the same partition area are not on the same circular ring to prevent the gas from forming an airflow perpendicular to the radial direction. At the same time, the notches can also divide the partition wall to prevent large areas of metal from contacting the wafer and affecting the cooling uniformity.

[0023] Furthermore, a pressure regulating valve for adjusting the pressure of the cooling gas and a needle valve for adjusting the flow rate of the cooling gas are provided on the pipeline outside the chuck connected to the air inlet.

[0024] On the basis of accelerating the cooling efficiency, the cooling rate can be controlled by adjusting the pressure and flow of the cooling gas.

[0025] Furthermore, the height of the metal suction nozzle is equal to the height of the partition wall, and the fluororubber suction cup exceeds the periphery of the metal suction nozzle.

[0026] With this design, if the wafer is not deformed, since the fluororubber suction cup has a certain thickness, the wafer adsorbed by the fluororubber suction cup will definitely be higher than the partition wall, and the wafer will not contact the partition wall, thereby improving cooling efficiency.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0028] By adopting the design scheme of the invention, the wafer is transported / received by the ejector pin and adsorbed and fixed by the vacuum suction cup. The wafer can be completely fixed in the form of three points and one plane, and the cooling gas flow rate is increased and the temperature is reduced faster through the cooperation of the separation area.

[0029] On the basis of accelerating the cooling efficiency, the cooling rate can be controlled by adjusting the pressure and flow of the cooling gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the top view of the structure of the present invention;

[0031] Figure 2 It is a schematic diagram of the cross-sectional structure of the present invention;

[0032] Figure 3 Schematic diagram of the structure of the vacuum suction cup of the present invention;

[0033] Figure 4 Schematic diagram of the structure of the partition wall of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] like Figures 1 to 4 As shown, a wafer cooling chuck includes a circular chuck body with an air inlet 1 at the center of the circle, a focusing ring 2 is provided near the center of the circle on the chuck body, and six partition walls 3 separated by equal angles extend from the outer wall of the focusing ring 2 to divide the chuck body into six partition areas 4. The partition walls 3 extend to the edge of the chuck body, and there are guide holes 5 on the focusing ring 2 between two adjacent partition walls 3. There is at least one ejector hole 6 on the chuck body of three non-adjacent partition areas 4. The ejector drive system drives the ejector 7 (the ejector and the drive system are not within the design scope of this chuck) to move vertically through the ejector hole 6 to complete the function of receiving and transmitting the wafer. The chuck bodies of the remaining partition areas 4 are all provided with vacuum suction cups 16, and the vacuum suction cups 16 are connected to the same factory vacuum pipeline or vacuum pump (not shown).

[0037] The air inlet is directly connected to the air compressor or factory compressed air through a pipe, and can also be connected to the nitrogen pipeline for cooling to room temperature.

[0038] The vertical movement of the three ejector pins in the ejector pin holes can stably receive the wafer delivered after the previous process step and be fixed by three vacuum suction cups. The adsorption of the suction cups can better fix the wafer. Considering that the wafer may deform, a three-point fixing method is adopted, which is obviously more conducive to the uniformity of cooling.

[0039] By arranging a plurality of partition walls and the cooperation of the partition areas, the flow of the cooling gas in the partition areas has the required directionality and at the same time has a certain flow rate, thereby improving the cooling efficiency.

[0040] A needle valve 9 and a shut-off valve are provided on the pipeline outside the chuck for connecting to the vacuum suction cup 16 .

[0041] Since the wafer may be deformed, if the wafer has no deformation or the deformation is relatively small, lower the vacuum suction volume. At the same time, the suction force of the three vacuum suction cups can also correct the slight deformation of the wafer. If the wafer is severely deformed, increase the vacuum suction volume to ensure stable adsorption.

[0042] The vacuum suction cup 16 includes a funnel-shaped metal suction nozzle 10 extending from the chuck body and a fluororubber suction cup 11 adhered to the inner surface of the metal suction nozzle 10 .

[0043] Make the contact area between the vacuum chuck and the wafer softer.

[0044] A circular support ring 12 is provided on the edge of the chuck body. The end of the partition wall 3 at the edge of the chuck body abuts against the support ring 12. The support ring 12 has a plurality of openings 13 that can penetrate to the outside.

[0045] The support ring acts as a bracket.

[0046] The focusing ring 2 , the partition wall 3 and the support ring 12 have the same height.

[0047] Several small contact points 14 are formed on the top of the partition wall 3 , and there is at least one notch 15 on the partition wall 3 for penetrating the adjacent partition area 4 .

[0048] When the wafer adsorbed by the vacuum suction cup is deformed, the wafer may come into contact with the partition wall. The design of small contact points reduces the contact area between the partition wall and the wafer and improves the uniformity of cooling. The notches on the partition wall are to prevent the cooling temperature from being unbalanced due to different cooling gas pressures in each partition area.

[0049] The same partition wall can have multiple notches. The notches on the two partition walls in the same partition area are not on the same circular ring to prevent the gas from forming an airflow perpendicular to the radial direction. At the same time, the notches can also divide the partition wall to prevent large areas of metal from contacting the wafer and affecting the cooling uniformity.

[0050] The pipeline outside the chuck connected to the air inlet is also provided with a pressure regulating valve (not shown) for regulating the pressure of the cooling gas and a needle valve 9 for regulating the flow rate of the cooling gas.

[0051] On the basis of improving the cooling efficiency, the cooling rate can be controlled by adjusting the pressure and flow of the cooling gas.

[0052] The height of the metal suction nozzle 10 is equal to the height of the partition wall 3 , and the fluororubber suction cup 11 extends beyond the periphery of the metal suction nozzle 10 .

[0053] With this design, if the wafer is not deformed, since the fluororubber suction cup has a certain thickness, the wafer adsorbed by the fluororubber suction cup will definitely be higher than the partition wall, and the wafer will not contact the partition wall, thereby improving cooling efficiency.

Claims

1. A wafer cooling chuck, characterized in that: The invention comprises a circular chuck body having an air inlet at the center thereof, a focusing ring disposed near the center thereof, six equiangular partition walls extending from the outer wall of the focusing ring, dividing the chuck body into six partition areas, the partition walls extending to the edge of the chuck body, a guide hole disposed on the focusing ring between two adjacent partition walls, at least one ejector pin hole disposed on the chuck body in each of three non-adjacent partition areas, and vacuum cups disposed on the chuck body in the remaining three partition areas, the vacuum cups being connected to the same vacuum pump; A plurality of small contact points are formed on the top of the partition wall, and at least one notch is provided on the partition wall for penetrating adjacent partition areas; A needle valve and a shut-off valve are provided on the pipeline outside the chuck for connecting to the vacuum suction cup; The vacuum suction cup comprises a funnel-shaped metal suction nozzle extending from a chuck body and a fluororubber suction cup adhered to the inner surface of the metal suction nozzle.

2. The wafer cooling chuck according to claim 1, wherein: A circular support ring is provided on the edge of the chuck body, and a partition wall is connected to the support ring at the end of the edge of the chuck body. The support ring has a plurality of openings that can penetrate the outside world.

3. The wafer cooling chuck according to claim 1 or 2, characterized in that: The focusing ring, dividing wall and support ring are of the same height.

4. The wafer cooling chuck according to claim 1, wherein: A flow meter and a needle valve capable of adjusting the flow of the air inlet are also provided on the pipeline outside the chuck connected to the air inlet.

5. The wafer cooling chuck according to claim 1, wherein: The height of the metal suction nozzle is equal to the height of the partition wall, and the fluororubber suction cup exceeds the periphery of the metal suction nozzle.

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