Electrostatic chuck with substrate backside cleaning and heat dissipation

Abstract

An electrostatic substrate chuck with substrate backside cleaning to prevent accidental backside deposition and provide heat dissipation to prevent or mitigate seal failure.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority to U.S. Application No. 15 / 886,098, filed on February 1, 2018, which is incorporated herein by reference for all purposes.

[0003] background

[0004] The present application relates to an electrostatic substrate chuck, which is widely used in various manufacturing tools, such as thin film deposition, plasma etching, photoresist stripping, substrate cleaning, photolithography, ion implantation, etc.

[0005] An electrostatic chuck (ESC) works by applying a charge of one polarity on the clamping surface and a charge of the opposite polarity on the substrate. Since opposite charges attract, the substrate is held or clamped in place by the electrostatic force generated. Summary of the invention

[0006] An ESC substrate pedestal is disclosed. The ESC substrate pedestal includes: an electrostatic chuck having a clamping surface for clamping a substrate; a pedestal frame; and the pedestal rod arranged to support the electrostatic chuck and mounted on the pedestal frame. The pedestal rod includes: (a) a rod wall, one or more conduits are arranged in or near the rod wall, which are used to supply gas to the electrostatic chuck; (b) a heat exchange surface, which is used to exchange heat from the rod wall to a heat dissipation element arranged on the pedestal frame; and (c) a sealing interface arranged to engage with a seal arranged between the rod wall and the pedestal frame, wherein the sealing interface is offset from the heat exchange surface on the cylindrical wall of the rod by a sufficient distance so that the seal is subjected to less heat relative to the heat exchange surface.

[0007] In a non-exclusive embodiment, the base rod is cylindrical and defines an outer cylindrical wall surface and an inner cylindrical wall surface, and the one or more conduits are formed between the outer cylindrical wall surface and the inner cylindrical wall surface, respectively.

[0008] In another non-exclusive embodiment, the base rod comprises: a first distal end arranged to support the electrostatic chuck; and a second distal end comprising the sealing interface arranged to engage with the seal. The heat exchange surface is intermediate the first distal end and the second distal end of the base rod.

[0009] In another non-exclusive embodiment, the one or more conduits are fluidly connected to a gas distribution network disposed on the electrostatic chuck, and the one or more conduits are arranged to supply the gas to the gas distribution network to generate a positive gas pressure on the back side of the substrate when the substrate is clamped to the clamping surface.

[0010] In another non-exclusive embodiment, the gas distribution network includes a pattern of channels and gas outlets arranged on the electrostatic chuck for evenly distributing gas across the clamping surface.

[0011] In yet another non-exclusive embodiment, the clamping surface of the electrostatic chuck further comprises an annular seal arranged to create a local seal around the periphery of the substrate when the substrate is clamped onto the clamping surface, wherein the local seal is arranged to enable a positive gas flow to flow from the back side of the substrate into the atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present application and its advantages may be best understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a block diagram of a substrate manufacturing tool for processing a substrate according to a non-exclusive embodiment.

[0014] Figure 2A is a cross-sectional view of an electrostatic substrate pedestal according to another non-exclusive embodiment.

[0015] Figure 2B is an enlarged view of the base rod of the electrostatic substrate base.

[0016] Figure 3 is a view of a clamping surface of an electrostatic substrate pedestal according to yet another non-exclusive embodiment.

[0017] In the accompanying drawings, similar reference numerals are sometimes used to indicate similar structural elements. It should also be understood that the descriptions in the accompanying drawings are schematic and not to scale. DETAILED DESCRIPTION

[0018] The present invention will now be described in detail with reference to several non-exclusive embodiments shown in the accompanying drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without some or all of these specific details. In other cases, known process steps and / or structures are not described in detail to avoid making the present invention unclear unnecessarily.

[0019] Figure 1 is a block diagram of a substrate processing tool 100 that can be used in non-exclusive embodiments. In this example, the processing tool 100 includes a processing chamber 102, a gas source 104, a radio frequency (RF) source 106, a bias source 108, an exhaust pump 110, a temperature controller 112, a vacuum source 114, and a controller 116.

[0020] The processing chamber 102 includes an element 118 coupled to an RF source 106 and an electrostatic chuck (ESC) substrate pedestal 120 for clamping a substrate 122 .

[0021] During operation of the tool 100, a substrate 122 is clamped on an ESC substrate pedestal 120 located in a process chamber 102, which contains a gas provided by a source 104. When RF power from the source 106 is applied to the plasma element 118, a plasma is generated for processing the substrate 122 within the process chamber 102. Depending on the type of tool, the plasma can be used to process the substrate 122 in a variety of ways, including thin film deposition, etching, etc.

[0022] Also during operation, the controller 116 can selectively control a number of operations within the chamber 102, such as applying a bias to the substrate 122 via the bias source 108, exhausting plasma or other gases from the chamber 102 via the exhaust pump 110, and controlling the temperature of the substrate pedestal 120 and / or the substrate 122 via the temperature controller 112 and the vacuum source 114. Because each of these elements and their operation are well known, a detailed description is not provided herein for the sake of brevity.

[0023] exist Figure 1 In the embodiment of the present invention, various electrical and / or supply tubes (hereinafter generally referred to as "pipes") are arranged between the various components 108 to 116 and the substrate pedestal 120. It should be noted that in order not to overly complicate the details of the drawings, the arrangement shown in the drawings is simplified to a single connection 124. As is well known, the paths of the various electrical and supply tubes in and out of the chamber 102 and / or the substrate pedestal 120 are complicated, but for the sake of brevity, they will not be described here.

[0024] In a specific but non-exclusive embodiment, tool 100 is an atomic layer deposition (ALD) tool. In this specific embodiment, a thin film deposit is grown on a substrate by exposing the surface of the substrate to alternating gaseous substances (commonly referred to as precursors). For example, a first precursor can be added to chamber 102 in a first process step. After the first precursor material has been absorbed or deposited on the surface of the substrate, any excess material is removed from chamber 102. Then, in a second process step, a second precursor is introduced into chamber 102 and deposited on the surface of the substrate. When this step is completed, any excess second precursor is removed from chamber 102. The above process can be repeated multiple times until a film of desired thickness is obtained. For example, a specific but non-exclusive ALD process may include multiple steps: (1) applying a precursor, (2) clearing the chamber of precursors, (3) reacting the deposited precursor with a plasma or converting it with a plasma, and then (4) repeating this 3-step process multiple times. In other embodiments, other steps not described here can be used as needed.

[0025] Although ALD tools are capable of depositing very thin films, their use is problematic for a number of reasons. During the deposition process, both the substrate and the substrate base are subjected to intense heat. Such heat may cause various seals and other equipment disposed on the substrate base to malfunction. Another problem with ALD tools is that the particles of the deposited film material may be so small that they may accidentally deposit on the back side of the substrate. In the present application, applicants have devised solutions to these problems, as described below.

[0026] Reference Figure 2A , shows a cross-sectional view of an ESC substrate pedestal 120 according to a non-exclusive embodiment. The ESC substrate pedestal 120 includes an ESC chuck 202 having a clamping surface 204 for clamping a substrate (not shown), a pedestal frame 206, and a pedestal rod 208 arranged to support the ESC chuck 202 and mounted on a recess 213 provided in the pedestal frame 206. .

[0027] The base rod 208 includes a first distal end 210 and a second distal end 212, the first distal end 210 being arranged to support the ESC chuck 202. Near the distal end 212, a sealing interface 214 is configured to engage a seal between it and an opposing second sealing interface 218 located in a recess 213 of the base frame 206. In a non-exclusive embodiment, the seal includes a plurality of O-rings 216A and 216B made of an elastomer (e.g., a perfluorinated or fluorinated elastomer) that is compatible with the chemical process and temperature. In alternative embodiments, the seals 216A and 216B may be fluorocarbons, silicones, or fluorinated. In other embodiments, the seals 216A and 216B are capable of operating at temperatures of 150°C or higher, ideally with minimal risk of failure over an extended period of time.

[0028] The base rod 208 also includes a heat exchanging element 220 intermediate the first distal end 210 and the second distal end 212 of the base rod 208. In a non-exclusive embodiment, the heat exchanging surface 220 is a protrusion extending outwardly from the base wall 208 and is arranged to be in thermal contact with a heat dissipating element 222 disposed on the base frame 206. With this arrangement, both the element 222 and the base frame 206 dissipate heat.

[0029] Mechanical fastening elements 215, such as bolts or screws, are arranged to mechanically fasten the heat sink element 222 and the base rod 208 to the base frame 206. When assembling the substrate base 120, the base rod is inserted into the recess 213 of the base frame 206. The heat sink element 222 is then mounted on top of the base frame 206 so that the protrusions defining the heat exchange surface 220 protruding from the base rod 208 are "sandwiched" between the heat sink element 222 and the base. Thus, when fastened by the elements 215, the three components are fastened together in the form of a single assembly. For ease of assembly, the heat sink element 222 can be divided into multiple parts, for example, the heat sink element 222 can be made of two or more plates (for example, designed as two 180 degree semicircular plates around the base rod 208).

[0030] Note that the heat exchange surface 220 is offset from the sealing interface 214 and the seals 216A / 216B along the length of the pedestal rod 208. With this arrangement, heat generated during processing of a substrate clamped on the clamping surface 204 is at least partially transferred to the heat sink element 222 and then to the location of the seals 216A and 216B. As a result, the seals 216A and 216B are maintained at a lower temperature than the heat exchange surface 220 of the pedestal rod 208.

[0031] In other non-exclusive embodiments, the base rod is cylindrical in shape and defines an outer cylindrical wall surface 224A and an inner cylindrical wall surface 224B. One or more conduits 226 are formed between the outer cylindrical wall surface 224A and the inner cylindrical wall surface 224B, respectively. Alternatively, one or more conduits (not shown) are arranged adjacent to the outer cylindrical wall surface 224A and / or the inner cylindrical wall surface 224B. It should be noted that the term "conduit" used herein should be broadly interpreted to cover any passage for conveying gas, such as but not limited to a tube, a hollow cylinder, a fluid line, a conduit, a pipe, a hose, etc.

[0032] One or more conduits 226 are connected to a gas distribution network ( Figure 2A and Figure 2B ) are fluidically connected.

[0033] In other embodiments, the base rod 208 can be made of a variety of thermally conductive materials. Such materials can include, but are not limited to, aluminum nitride, aluminum oxide, ceramics, other thermally conductive materials, or any combination thereof.

[0034] Figure 2B is an enlarged view of the base rod 208 of the ESC substrate base 120, which shows a better view of many of the features described above. Specifically, Figure 2B It shows:

[0035] (a) a heat exchange surface 220 extending or protruding outwardly from the stem wall 208 and arranged to be in thermal contact with a heat dissipation element 222 disposed on the base frame 206;

[0036] (b) a sealing interface 214 arranged to engage with O-ring seals 216A and 216B between the sealing interface 214 and an opposing second sealing interface 218 positioned in a recess 213 of the base frame 206; and

[0037] (c) A gas conduit 226 formed between the outer cylindrical wall surface 224A and the inner cylindrical wall surface 224B of the base rod 208.

[0038] As in Figure 2B As more clearly seen in , the heat exchanging surface 220 and the sealing interface 214 are offset by a distance 235 .

[0039] In various embodiments, the offset range can vary significantly. For example, the offset can be in the range of about 0.25 inches (6.35 mm) or more, from 0.25 to 8.0 inches (203.2 mm) or more, from 0.25 to 1.5 inches (38.1 mm), from 0.5 to 5.0 inches (12.7 mm to 127 mm), or any other suitable offset greater than 0.25. The actual offset dimension 235 used in a given embodiment can vary according to several factors, such as the length of the base rod 208, the heat to be dissipated, the type of seal 216A and / or 216B and / or the life of heat resistance, etc. Therefore, for specific but non-exclusive embodiments, the offset dimension 235 can be any value exceeding 0.25 inches (6.25 mm). It should be understood that any specific dimensions provided herein are exemplary only and not restrictive. Generally, the larger the offset distance, the larger the temperature difference.

[0040] In addition, in a non-exclusive embodiment, seal 216A and / or 216B is maintained at about 200 degrees Celsius or lower, preferably maintained at about 150 to 160 degrees Celsius. In addition, it should be understood that these temperature values ​​are only exemplary and are not intended to be limiting. In actual embodiments, a wide range of temperature differences and target temperatures can be used.

[0041] Finally, the arrangement of the conduit 226 shown is not intended to be limiting. As previously described, the conduit may also be positioned adjacent to the outer cylindrical wall surface 224A and / or the inner cylindrical wall surface 224B.

[0042] With the above arrangement, the central region 230 of the base rod 208 is relatively unoccupied. As a result, there is room for routing cables, supply chambers, etc. (eg, “ducts”) from the various components 108 to 114 through the central region 230 to the electrostatic chuck 202 .

[0043] Reference Figure 3 , shows a top view of the clamping surface 204 of the electrostatic chuck 202. In this embodiment, the surface 204 includes a gas distribution network 302 and an annular seal 304.

[0044] The gas distribution network 302 includes gas outlets 306, a grid of channels 308, and a gimbal 310. The gas outlets 306 are in fluid communication with one or more conduits 226 that supply gas to the electrostatic chuck 202 via the pedestal rod 208. The gas supplied via the outlets 306 is then distributed through the channels 308 near the back side of the substrate 122. The gimbal 310 helps balance the gas pressure across the clamping surface 204. As a result, a substantially equal positive pressure is generated over the surface area of ​​the back side of the substrate 122.

[0045] The annular seal 304 is arranged to contact the periphery or outer circumference of the substrate 122 when the substrate 122 is clamped to the surface 204. The annular seal 304 is arranged to create a local seal, i.e., the positive pressure gas on the back side of the substrate 122 is allowed to slowly escape into the surrounding atmosphere in the chamber 102. In other words, the positive gas flow sweeps or prevents deposition material and / or other particles or contaminants from entering the space between the back side of the substrate 122 and the clamping surface 204. As a result, accidental deposition or contamination is avoided or significantly reduced.

[0046] Additionally, the gas may also be used for cooling by enhancing heat conduction between the substrate 122 and the clamping surface 204 .

[0047] In various embodiments, the positive pressure generated by the gas is in the range of about 10 to 30 Torr. In a particular embodiment, the gas used is helium. However, other purge gases may be used, including nitrogen, argon, or other inert gases.

[0048] In a non-exclusive embodiment, the annular seal 304 is made of a highly polished and flat ceramic. In other embodiments, the annular seal 304 is made of a substantially flat material, typically with a flatness of less than 0.001 inches (0.0254 mm) per 12 inches (304.8 mm). Again, these flatness characteristics are merely exemplary, and annular seals with more or less flatness characteristics may be used.

[0049] Notice, Figure 3The specific embodiments shown in the figure are exemplary and should not be construed as limiting in any way. For example, the number of gas outlets 306 can be greater or less than the six (6) shown in this particular embodiment. In other embodiments, each gas outlet 306 is connected to a dedicated conduit 226. In other embodiments, the conduit 226 can supply more than one outlet 306. In addition, the grid of channels 308 can adopt any pattern and is not limited to the "star" pattern shown in the figure.

[0050] Therefore, the above-described embodiments solve many problems, including:

[0051] (1) A gas such as helium or other sweep gas is provided through the susceptor rod 208 so that pressure can be generated on the back side of the substrate 122 when the substrate is clamped. This positive pressure helps prevent accidental contamination and deposition of thin film materials, and also helps cool the substrate.

[0052] (2) gas conduit 226 is disposed within or adjacent to the wall of pedestal rod 208, allowing purge gas to be supplied to clamping surface 204. Additionally, space 230 within pedestal rod 208 is freed to allow other necessary "plumbing" to be supplied to electrostatic chuck 202; and

[0053] (3) Seals 216A and 216B deflect heat dissipation at heat exchange surface 220, resulting in a significant decrease in temperature near seals 216A and 216B. As a result, the likelihood of seals 216A and 216B melting and / or failing is greatly reduced.

[0054] It should be understood that although the present application is described in the context of an ADL tool, this is by no means intended to be limiting. Rather, the ESC substrate pedestal 120 described herein may be used in a variety of substrate processing tools, including but not limited to chemical vapor deposition tools, photolithography tools, plasma etching or chemical etching tools, ion implantation tools, substrate cleaning tools, and the like.

[0055] Although only a few embodiments have been described in detail, it should be appreciated that the present application may be implemented in many other forms without departing from the spirit or scope of the disclosure provided herein. For example, the substrate may be a semiconductor wafer, a discrete semiconductor device, a flat panel display, or any other type of workpiece.

[0056] Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and are not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. An electrostatic chuck substrate base, comprising: an electrostatic chuck having a clamping surface for clamping a substrate, Base frame, A heat dissipation element disposed on the base frame; and a pedestal rod arranged to support the electrostatic chuck and mounted to the pedestal frame, the pedestal rod comprising: (a) a rod wall, one or more conduits disposed within or adjacent to the rod wall for supplying gas to the electrostatic chuck; (b) a heat exchange surface for exchanging heat from the rod wall to the heat dissipation element disposed on the base frame, wherein the heat exchange surface is a protrusion extending from the rod wall, the protrusion being arranged to contact the heat dissipation element on the base frame; and (c) a sealing interface arranged to engage a seal disposed between the stem wall and the base frame, wherein the sealing interface is offset from the heat exchange surface on the stem wall by an offset distance such that the seal is subjected to less heat relative to the heat exchange surface, Wherein, the base rod comprises: a first distal end arranged to support the electrostatic chuck; and A second distal end includes the sealing interface arranged to engage the seal, wherein the heat exchange surface is intermediate the first distal end and the second distal end of the base rod.

2. The electrostatic chuck substrate base according to claim 1, wherein: The offset distance is greater than 0.25 inches (6.35 mm).

3. The electrostatic chuck substrate base according to claim 1, wherein: The base frame also includes: a recess for receiving the base rod; and a second sealing interface arranged to be opposite to the sealing interface of the rod wall when the rod wall of the base rod is located in the recess of the base frame, Wherein, the sealing member is one or more O-rings, and the O-rings are located between the sealing interface of the rod wall and the second sealing interface of the base frame.

4. The electrostatic chuck substrate base according to claim 1, wherein: The seal is maintained at a temperature of 200° C. or less.

5. The electrostatic chuck substrate base according to claim 1, wherein: The base rod is cylindrical and defines an outer cylindrical wall surface and an inner cylindrical wall surface, and the one or more conduits are formed between the outer cylindrical wall surface and the inner cylindrical wall surface, respectively.

6. The electrostatic chuck substrate base according to claim 1, wherein: The one or more conduits are disposed adjacent to an outer wall or an inner wall of the base rod.

7. The electrostatic chuck substrate base according to claim 1, wherein: The base rod is at least partially made of one of the following: (a) Aluminum nitride; (b) Aluminium oxide; (c) Ceramics; (d) thermally conductive materials; and (e) Any combination of (a) to (d).

8. The electrostatic chuck substrate base according to claim 1, wherein: The one or more conduits are in fluid communication with a gas distribution network disposed on the electrostatic chuck, and the one or more conduits are arranged to supply the gas to the gas distribution network to generate a positive gas pressure on the back side of the substrate when the substrate is clamped onto the clamping surface.

9. The electrostatic chuck substrate base according to claim 8, wherein: The positive gas pressure is in the range of 10 to 30 Torr.

10. The electrostatic chuck substrate base according to claim 8, wherein: The gas distribution network includes a pattern of channels and gas outlets arranged on the electrostatic chuck for evenly distributing the gas over the clamping surface.

11. The electrostatic chuck substrate base of claim 1, wherein: The clamping surface of the electrostatic chuck also includes an annular seal, which is arranged to create a local seal around the periphery of the substrate when the substrate is clamped to the clamping surface, wherein the local seal is arranged to enable a positive gas flow to flow from the back side of the substrate into the atmosphere.

12. The electrostatic chuck substrate base of claim 11, wherein: The annular seal is ceramic.

13. The electrostatic chuck substrate base of claim 1, wherein: The gas supplied to the electrostatic chuck is a sweep gas used to prevent inadvertent deposition of material onto a back side of the substrate when the substrate is clamped to the clamping surface.

14. The electrostatic chuck substrate base of claim 1, wherein: The gas is one of the following: (a) Helium; (b) nitrogen; (c) argon; or (d) Inert gases.

15. The electrostatic chuck substrate base of claim 1, wherein: The heat dissipating element is a circular plate comprising two or more sections, the circular plate being mechanically fastened to the base frame.

16. The electrostatic chuck substrate pedestal of claim 1, further comprising one or more mechanical fasteners to mechanically fasten the pedestal rod, the pedestal frame, and the heat sink element into an assembly.

17. The electrostatic chuck substrate base of claim 3, wherein: The one or more O-rings are made of an elastomer capable of withstanding temperatures of at least 150°C.

18. The electrostatic chuck substrate base of claim 3, wherein: The one or more O-rings are made of an elastomer selected from the group consisting of: Perfluoroelastomer; Fluorinated elastomers; Fluorocarbon elastomer; or Silicone elastomer.

19. The electrostatic chuck substrate base of claim 11, wherein: The annular seal is flat and has a flatness of 0.001 inch (0.0254 mm) or less per 12 inches (304.8 mm).

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