Cooling system and electrostatic chuck

Abstract

The invention relates to the technical field of semiconductor processing, in particular to a cooling system and an electrostatic chuck. Comprising an inflow hole and an outflow hole which are respectively arranged on the opening surface; the cooling channel is positioned in the cavity and is respectively communicated with the inflow hole and the outflow hole; and the distance between the cooling channel and the adsorption surface is reduced along with the change of the position in the path from the inflow hole to the outflow hole. In the application, on the cooling channel, the distance between the cooling channel and the adsorption surface is gradually reduced in the path from the inflow hole to the outflow hole, and the distance between the cooling channel and the adsorption surface can be gradually reduced along with the continuous deterioration of the cooling effect of the cooling liquid, so that the cooling effect of the cooling liquid is gradually enhanced; and the temperature of the wafer can be uniform, so that the purpose of uniformly regulating and controlling the temperature of the whole electrostatic chuck and the wafer is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor processing, and in particular to a cooling system and an electrostatic chuck. Background Art

[0002] Electrostatic chucks (ESCs) are commonly used in semiconductor processing and testing. Their electrostatic attraction offers an advantageous alternative to traditional mechanical clamping and vacuum methods, playing a crucial role in wafer securing and temperature control. Wafer temperature is a crucial factor in semiconductor processing, as slight temperature differences can lead to significant deviations during processing. Therefore, temperature uniformity control is a crucial issue in semiconductor-related processes. Maintaining uniform wafer temperature ensures the ultimate goal of semiconductor processing is achieved.

[0003] Currently, when the wafer is adsorbed, as the coolant gradually flows inward, the temperature of the coolant gradually increases, and the cooling effect of the coolant continues to deteriorate, resulting in poor temperature uniformity of the wafer on the adsorption surface of the electrostatic chuck. Summary of the Invention

[0004] In view of this, the present invention provides a cooling system and an electrostatic chuck to solve the problem of poor wafer temperature uniformity caused by the continuous deterioration of the cooling effect of the coolant.

[0005] In a first aspect, the present invention provides a cooling system disposed on an electrostatic chuck, wherein the electrostatic chuck includes an open surface and an adsorption surface, and a cavity is defined between the open surface and the adsorption surface, comprising:

[0006] The inlet hole and the outlet hole are respectively arranged on the opening surface;

[0007] a cooling channel, located in the cavity and connected to the inlet and outlet holes respectively;

[0008] In the path from the inlet hole to the outlet hole, the distance between the cooling channel and the adsorption surface decreases as the position changes.

[0009] In the application, on the cooling channel, the distance between the cooling channel and the adsorption surface gradually becomes smaller in the path from the inlet hole to the outlet hole. As the cooling effect of the coolant continues to deteriorate, the distance between the cooling channel and the adsorption surface becomes closer and closer, gradually enhancing the cooling effect of the coolant, and making the temperature of the wafer uniform, thereby achieving the purpose of uniform temperature control of the entire electrostatic suction cup and the wafer.

[0010] In an optional embodiment, the cooling channels are distributed in a spiral shape within the cavity. The spiral distribution of the cooling channels can extend the flow path of the coolant in the cavity and increase the contact time between the coolant and the electrostatic chuck, thereby more fully absorbing heat and improving cooling efficiency. In addition, the spiral distribution can make the cooling effect cover a larger area of ​​the electrostatic chuck, especially the area from the edge to the center, so that all parts of the wafer surface can be cooled more evenly, avoiding processing deviations caused by local overheating or insufficient cooling, and improving the quality and stability of semiconductor processing.

[0011] In an optional embodiment, the cooling channels are spirally distributed around the middle area of ​​the cavity. Spiral distribution of the cooling channels around the middle area can strengthen the cooling of the center area of ​​the wafer in a targeted manner. Since in some semiconductor processing processes, the center area of ​​the wafer may be more prone to overheating due to more concentrated heat, this design can dissipate heat more effectively in the center area, making the overall temperature of the wafer more balanced, helping to improve processing accuracy and reduce wafer deformation or other processing defects caused by temperature differences.

[0012] In an optional embodiment, the spiral shape of the cooling channel has at least two turns. Compared to single-turn spirals or other simpler shapes, cooling channels with at least two turns can further increase the coolant flow rate and heat exchange area with the chuck body. This allows the coolant to circulate and absorb heat more fully within the cavity, more effectively removing heat generated by the wafer and chuck, thereby significantly improving the cooling effect and ensuring that the wafer maintains a stable temperature throughout the entire processing process, meeting the temperature control requirements of high-precision semiconductor processing.

[0013] In an optional embodiment, the inlet hole is located at the edge of the opening surface, and the outlet hole is located in the middle area of ​​the opening surface. The layout of arranging the inlet hole at the edge and the outlet hole in the middle is conducive to guiding the coolant to flow from the edge to the center, forming a cooling path from the outside to the inside. This design allows the coolant to cool the edge area first, and then gradually advance to the center. Combined with the design of changing the distance between the cooling channel and the adsorption surface, it can better balance the cooling effect of the edge and center areas, avoid the problem of insufficient cooling of the edge or excessive cooling of the center due to the coolant flowing into the center first, and improve the temperature uniformity of the wafer.

[0014] In an optional embodiment, the inlet and outlet holes are both located at the edge of the opening surface. The arrangement of the inlet and outlet holes at the edge can simplify the structure of the electrostatic chuck and facilitate the arrangement and processing of the cooling channel in the cavity. At the same time, this layout makes the flow path of the coolant in the cavity relatively concentrated in the area close to the edge, and the cooling effect on the edge area is more significant. It is suitable for some semiconductor processing processes that have high requirements for edge temperature control. It can improve the cooling efficiency of the edge area to a certain extent and reduce the temperature difference caused by the edge effect.

[0015] In an optional embodiment, the inlet and outlet holes are both located in the middle area of ​​the opening surface. When the inlet and outlet holes are both located in the middle, the coolant circulates primarily in the pipes near the middle area. This design allows for more direct and concentrated cooling of the middle area. For situations where process characteristics result in a high amount of heat generated in the middle area, it can quickly and effectively reduce the temperature of the middle area, preventing overheating in the middle from affecting the processing quality of the wafer. It can also cooperate with other cooling structures to optimize the temperature field distribution of the entire electrostatic chuck.

[0016] In an optional embodiment, the outflow hole is located at the edge of the opening surface, and the inflow hole is located in the middle area of ​​the opening surface. The layout of the inflow hole in the middle and the outflow hole at the edge allows the coolant to flow from the center to the edge. This flow direction allows the coolant to cool the middle area first and then gradually diffuse to the edge area. This creates a synergistic effect with the design of the variable distance between the cooling channel and the adsorption surface, making the cooling effect in the middle and edge areas more balanced, helping to achieve a uniform distribution of wafer surface temperature and meet the temperature gradient requirements of different semiconductor processing technologies.

[0017] In an optional embodiment, the cooling channels are evenly distributed within the cavity. Evenly distributed cooling channels can ensure that all areas within the cavity are covered by cooling channels, avoiding cooling dead corners. This allows the temperature of the entire electrostatic chuck adsorption surface to be evenly adjusted, and no matter which part of the wafer is located, it can receive roughly the same cooling effect, thereby effectively reducing wafer stress and deformation caused by local cooling differences, improving the consistency and yield of semiconductor processing, and is particularly important for the processing of large-size wafers.

[0018] In a second aspect, the present invention further provides an electrostatic chuck comprising the cooling system as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of a first distribution of inlet holes and outlet holes according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic plan view of a first distribution of cooling channels according to an embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of a first distribution cross-section of the cooling channel according to an embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of a second distribution of inlet holes and outlet holes according to an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of a second distribution plane of cooling channels according to an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the second distribution cross-section of the cooling channel according to an embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 1. Electrostatic chuck; 2. Opening surface; 3. Adsorption surface; 4. Inlet hole; 5. Outlet hole; 6. Cooling channel; 7. Inlet pipe; 8. Outlet pipe. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0029] Electrostatic chucks (ESCs) are generally used in the processing and testing process of the semiconductor industry. The electrostatic adsorption effect they generate is an advantageous technology that can replace traditional mechanical holding and vacuum adsorption methods, and plays a vital role in fixing wafers and controlling temperature. The temperature of the wafer is a very important influencing factor in the semiconductor processing process. Slight temperature differences may cause large deviations in the processing process, so temperature uniformity control (Temperature Homogeneity Control) is an important issue in semiconductor-related processes. The uniformity of wafer temperature can ensure the realization of the ultimate goal of semiconductor processing. At present, the size of wafer processing is constantly increasing, and how to control temperature uniformity is a key issue. The cooling system (Coolant System) of the electrostatic chuck in the related technology has problems such as temperature control uniformity and low precision, and it is impossible to achieve uniform control of wafer temperature.

[0030] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0031] Example 1

[0032] The present invention provides a cooling system, which is provided on an electrostatic chuck 1, wherein the electrostatic chuck 1 includes an aperture surface 2 and an adsorption surface 3, with a cavity defined between the aperture surface 2 and the adsorption surface 3. Specifically, the electrostatic chuck 1 may further include an outer ring-shaped component, with the aperture surface 2 and the adsorption surface 3 respectively provided on either side of the outer ring-shaped component. The outer ring-shaped component, the aperture surface 2, and the adsorption surface 3 may enclose a cavity, including:

[0033] The inlet hole 4 and the outlet hole 5 are respectively provided on the opening surface 2;

[0034] a cooling channel 6, located in the cavity and connected to the inlet hole 4 and the outlet hole 5 respectively;

[0035] Coolant typically flows in through inlet hole 4 on the electrostatic chuck 1, exits through outlet hole 5 at the center, and flows into the internal cavity of the electrostatic chuck 1 through cooling channel 6. As the coolant gradually flows inward, the temperature of the coolant gradually increases, causing the cooling effect of the coolant to gradually deteriorate. When inlet hole 4 is located at the edge and outlet hole 5 is located in the middle area, the temperature in the center of the electrostatic chuck 1 is higher than that near the edge, which in turn leads to poor temperature uniformity of the wafer on the suction surface 3 of the electrostatic chuck 1, resulting in the surface temperature of the wafer not being able to fully meet the requirements of the corresponding process flow.

[0036] The opening surface 2 is provided with an inlet hole 4 and an outlet hole 5 of a cooling channel 6. The inlet hole is connected to the outlet hole 5. The inlet hole 4 is used to inject the coolant into the main body, and the outlet hole 5 is used to discharge the coolant in the electrostatic chuck 1.

[0037] In the path from the inlet hole 4 to the outlet hole 5 , the distance between the cooling channel 6 and the adsorption surface 3 decreases as the position changes.

[0038] In the application, on the cooling channel 6, the distance between the cooling channel 6 and the adsorption surface 3 gradually becomes smaller in the path from the inlet hole 4 to the outlet hole 5. As the cooling effect of the coolant continues to deteriorate, the distance between the cooling channel 6 and the adsorption surface 3 becomes closer and closer, gradually strengthening the cooling effect of the coolant, and making the temperature of the wafer uniform, achieving the purpose of uniform temperature control of the entire electrostatic chuck 1 and the wafer. The cooling channel 6 becomes closer and closer to the adsorption surface 3 of the electrostatic chuck 1 as it travels from the inlet hole 4 to the outlet hole 5, thereby disguisedly strengthening the cooling effect of the downstream coolant, thereby achieving uniform temperature control of the entire electrostatic chuck 1 and the wafer.

[0039] In an optional embodiment, as Figure 2 and Figure 4 As shown, the cooling channel 6 is distributed in the cavity in a spiral shape. The spiral distribution of the cooling channel 6 can extend the flow path of the coolant in the cavity and increase the contact time between the coolant and the electrostatic chuck 1, thereby more fully absorbing heat and improving the cooling efficiency. In addition, the spiral distribution can make the cooling effect cover a larger area of ​​the electrostatic chuck 1, especially the area from the edge to the center, so that all parts of the wafer surface can be cooled more evenly, avoiding processing deviations caused by local overheating or insufficient cooling, and improving the quality and stability of semiconductor processing.

[0040] The cooling channel 6 is spiral-shaped when viewed from above, as shown in the figure. This cooling system can improve the situation where the cooling effect of the coolant in the cooling channel 6 gradually deteriorates, and can improve the temperature uniformity of the surface of the electrostatic adsorption surface 3, thereby better controlling the temperature of the wafer.

[0041] In an optional embodiment, the cooling channels 6 are spirally distributed around the middle area of ​​the cavity. Spiral distribution of the cooling channels 6 around the middle area can specifically strengthen the cooling of the center area of ​​the wafer. Since in some semiconductor processing processes, the center area of ​​the wafer may be more susceptible to overheating due to more concentrated heat, this design can more effectively dissipate heat in the center area, making the overall temperature of the wafer more balanced, helping to improve processing accuracy and reduce wafer deformation or other processing defects caused by temperature differences.

[0042] In an optional embodiment, the spiral shape of the cooling channel 6 comprises at least two turns. Compared to single-turn spirals or other simpler shapes, a cooling channel 6 with at least two turns can further increase the coolant flow rate and heat exchange area with the chuck body. This allows the coolant to circulate and absorb heat more fully within the cavity, more effectively removing heat generated by the wafer and chuck, thereby significantly improving the cooling effect and ensuring that the wafer maintains a stable temperature throughout the entire processing process, meeting the temperature control requirements of high-precision semiconductor processing.

[0043] In an optional embodiment, as Figures 1 to 3 As shown, the inlet hole 4 is located at the edge of the opening surface 2, and the outlet hole 5 is located in the middle area of ​​the opening surface 2. The layout of arranging the inlet hole 4 at the edge and the outlet hole 5 in the middle is conducive to guiding the coolant to flow from the edge to the center, forming a cooling path from the outside to the inside. This design allows the coolant to cool the edge area first and then gradually advance to the center. Combined with the design of the distance change between the cooling channel 6 and the adsorption surface 3, it can better balance the cooling effect of the edge and center areas, avoid the problem of insufficient cooling of the edge or excessive cooling of the center due to the coolant flowing into the center first, and improve the temperature uniformity of the wafer.

[0044] An inlet hole 4 and an outlet hole 5 for the cooling liquid are arranged in the electrostatic chuck 1. The inlet hole 4 is connected to the outlet hole 5. During the process of the cooling liquid being injected from the inlet hole 4 and discharged from the outlet hole 5, the cooling liquid continuously absorbs heat, resulting in a decrease in its cooling effect. Based on this feature, as shown in the figure, an improved cooling channel 6 is provided in the electrostatic chuck 1. The cooling channel 6 may include an inlet pipe 7 and an outlet pipe 8 connected to each other. One end of the inlet pipe 7 is connected to the inlet hole 4, and one end of the outlet pipe 8 is connected to the outlet hole 5. As the inlet pipe 7 gradually connects to the outlet pipe 8 inside the electrostatic chuck 1 from the edge of the electrostatic chuck 1, the distance between the cooling channel 6 and the wafer surface is continuously shortened to compensate for the disadvantage that the cooling effect decreases as the cooling liquid approaches the descending outlet pipe 8, and to avoid the path loss of the cooling channel 6 causing the cooling liquid to heat up and weaken the cooling effect, thereby better controlling the temperature on the wafer surface and more quickly achieving the temperature uniformity required by the process flow.

[0045] In an optional embodiment, as Figures 4 to 6As shown, the inlet hole 4 and the outlet hole 5 are both located at the edge of the opening surface 2. The arrangement of the inlet hole 4 and the outlet hole 5 at the edge can simplify the structure of the electrostatic chuck 1 and facilitate the arrangement and processing of the cooling channel 6 in the cavity. At the same time, this layout makes the flow path of the coolant in the cavity relatively concentrated in the area close to the edge, and the cooling effect on the edge area is more significant. It is suitable for some semiconductor processing processes that have high requirements for edge temperature control. It can improve the cooling efficiency of the edge area to a certain extent and reduce the temperature difference caused by the edge effect.

[0046] As shown in the figure, the coolant generally flows in from the inlet hole 4 on the main body of the electrostatic chuck 1, flows out from the outlet hole 5 next to the inlet hole 4, and flows into the internal cavity of the electrostatic chuck 1 through the cooling channel 6. As the coolant gradually flows inward, the temperature of the coolant will gradually increase, causing the cooling effect of the coolant to continue to deteriorate, resulting in the temperature in the middle area of ​​the electrostatic chuck 1 being higher than the part close to the edge, which in turn causes the temperature uniformity of the wafer on the adsorption surface 3 of the electrostatic chuck 1 to be poor. As a result, the temperature of the wafer surface cannot fully meet the requirements of the corresponding process flow. This embodiment provides another structure of the cooling channel 6 on the basis of improving the temperature uniformity of the wafer on the surface of the electrostatic chuck 1, which can provide a different design method of the cooling channel 6 to the related technology. It can also improve the situation where the cooling effect of the coolant in the cooling channel 6 gradually deteriorates, and can improve the temperature uniformity of the wafer surface on the adsorption surface 3 of the electrostatic chuck 1, thereby better controlling the temperature of the wafer.

[0047] In an optional embodiment, the inlet hole 4 and the outlet hole 5 are both located in the middle area of ​​the opening surface 2. When the inlet hole 4 and the outlet hole 5 are both located in the middle, the coolant mainly circulates in the pipeline near the middle area. This design allows the middle area to be cooled more directly and concentratedly. For some situations where the middle area generates a lot of heat due to process characteristics, it can quickly and effectively reduce the temperature of the middle part to prevent overheating in the middle from affecting the processing quality of the wafer. At the same time, it can also cooperate with other cooling structures to optimize the temperature field distribution of the entire electrostatic chuck 1.

[0048] In an optional embodiment, the outlet hole 5 is located at the edge of the opening surface 2, and the inlet hole 4 is located in the middle area of ​​the opening surface 2. The layout of the inlet hole 4 in the middle and the outlet hole 5 at the edge allows the coolant to flow from the center to the edge. This flow direction allows the coolant to cool the middle area first and then gradually diffuse to the edge area. This creates a synergistic effect with the design of the cooling channel 6 with a variable distance from the adsorption surface 3, making the cooling effect in the middle and edge areas more balanced, helping to achieve a uniform distribution of wafer surface temperature and meet the temperature gradient requirements of different semiconductor processing technologies.

[0049] In an optional embodiment, the cooling channels 6 are evenly distributed in the cavity. The evenly distributed cooling channels 6 can ensure that all areas in the cavity are covered by the cooling channels 6, avoiding the occurrence of cooling dead corners. In this way, the temperature of the adsorption surface 3 of the entire electrostatic chuck 1 can be evenly adjusted, and no matter which part of the wafer is, it can receive roughly the same cooling effect, thereby effectively reducing the stress and deformation of the wafer caused by local cooling differences, improving the consistency and yield rate of semiconductor processing, and is particularly important for the processing of large-size wafers.

[0050] Example 2

[0051] The present invention also provides an electrostatic chuck comprising the cooling system as described above.

[0052] The present application can solve the problem of excessively high temperatures of wafers due to plasma bombardment during semiconductor processing by means of liquid cooling. Furthermore, by gradually shortening the distance between the inlet hole 4 and the outlet hole 5, and the distance between the cooling channel 6 and the adsorption surface 3 of the electrostatic chuck 1, the problem of decreased cooling effect of the coolant in the latter half of the process is reduced, thereby solving the problem of uneven temperature control of the adsorption surface 3 of the electrostatic chuck 1. The present application can ensure the cooling effect of the coolant through the improved structure of the cooling channel 6 of the electrostatic chuck 1, thereby ensuring the temperature uniformity of the adsorption surface 3 of the electrostatic chuck 1.

[0053] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A cooling system, arranged on an electrostatic chuck (1), wherein: The electrostatic chuck (1) comprises an opening surface (2) and an adsorption surface (3), wherein a cavity is provided between the opening surface (2) and the adsorption surface (3), and is characterized in that it comprises: An inlet hole (4) and an outlet hole (5) are respectively arranged on the opening surface (2); a cooling channel (6), located in the cavity and connected to the inlet hole (4) and the outlet hole (5) respectively; In the path from the inlet hole (4) to the outlet hole (5), the distance between the cooling channel (6) and the adsorption surface (3) decreases as the position changes.

2. The cooling system according to claim 1, characterized in that The cooling channel (6) is distributed in the cavity in a spiral shape.

3. The cooling system according to claim 2, characterized in that The cooling channels (6) are distributed in a spiral pattern around the middle area of ​​the cavity.

4. The cooling system according to claim 2, characterized in that The spiral shape of the cooling channel (6) has at least two turns of spiral structure.

5. The cooling system according to claim 1, wherein: The inlet hole (4) is located at the edge of the opening surface (2), and the outlet hole (5) is located in the middle area of ​​the opening surface (2).

6. The cooling system according to claim 1, wherein: The inlet hole (4) and the outlet hole (5) are both located at the edge of the opening surface (2).

7. The cooling system according to claim 1, characterized in that The inlet hole (4) and the outlet hole (5) are both located in the middle area of ​​the opening surface (2).

8. The cooling system according to claim 1, wherein: The outflow hole (5) is located at the edge of the opening surface (2), and the inflow hole (4) is located in the middle area of ​​the opening surface (2).

9. The cooling system according to claim 1, wherein: The cooling channels (6) are evenly distributed in the cavity.

10. An electrostatic chuck, characterized in that: Comprising a cooling system according to any one of claims 1 to 9.

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