Low temperature electrostatic chuck

Abstract

Embodiments described herein relate to a substrate support assembly that enables cryogenic operation of an electrostatic chuck (ESC) such that a substrate disposed on the electrostatic chuck (ESC) is maintained at a cryogenic processing temperature suitable for processing while maintaining other surfaces of a processing chamber at different temperatures. The substrate support assembly includes: an electrostatic chuck (ESC), an ESC base assembly coupled to the ESC, the ESC base assembly having a base channel disposed in the ESC base assembly, and a facility plate having a facility channel disposed in the facility plate. The facility plate includes a plate portion and a wall portion. The plate portion is coupled to the ESC base assembly and the wall portion is coupled to the ESC using a sealing assembly. A vacuum region is defined by the ESC, the ESC base assembly, a plate portion of the facility plate, a wall portion of the facility plate, and a sealing assembly.

Description

Background Art Technical Field

[0002] Embodiments of the present disclosure relate generally to semiconductor manufacturing, and more particularly to a substrate support assembly that enables cryogenic operation of an electrostatic chuck (ESC).

[0003] Related technical notes

[0004] Reliably producing nanometer and smaller features is one of the key technical challenges for the next generation of very large scale integration (VLSI) and ultra large scale integration (ULSI) of semiconductor devices. However, as the limits of circuit technology are pushed, the shrinking dimensions of VLSI and ULSI interconnect technologies place additional demands on processing capabilities. Reliably forming gate structures on substrates is important to the success of VLSI and ULSI and the ongoing efforts to increase circuit density and the quality of individual substrates and dies.

[0005] In order to reduce manufacturing costs, integrated chip (IC) manufacturers require each silicon substrate processed to have higher throughput and better device yield and performance. Some manufacturing technologies for next-generation devices being explored in current development need to be processed at low temperatures. Dry reactive ion etching uniformly maintains the substrate at low temperatures so that ions can bombard the upward surface of the material disposed on the substrate with reduced spontaneous etching, thereby forming a groove with smooth, vertical sidewalls. In addition, the selectivity of etching one material relative to another material can be improved at low temperatures. For example, as the temperature decreases, the selectivity between silicon (Si) and silicon dioxide (SiO2) increases exponentially.

[0006] Therefore, there is a need for an improved substrate support assembly suitable for use in cryogenic conditions. Summary of the invention

[0007] In one embodiment, a substrate support assembly is provided. The substrate support assembly includes: an electrostatic chuck (ESC), the electrostatic chuck (ESC) having a support surface and a bottom surface opposite to the support surface. The ESC has an adsorption electrode and one or more resistive heaters disposed in the ESC. The ESC base assembly is coupled to the ESC, and the ESC base assembly has a base channel disposed in the ESC base assembly. The facility plate has a facility channel disposed in the facility plate. The facility plate includes a plate portion and a wall portion. The plate portion is coupled to the ESC base assembly and the wall portion is coupled to the ESC using a sealing assembly. A vacuum region is defined by the ESC, the ESC base assembly, the plate portion of the facility plate, the wall portion of the facility plate, and the sealing assembly.

[0008] In another embodiment, a substrate support assembly is provided. The substrate support assembly includes: an electrostatic chuck (ESC) having a support surface and a bottom surface opposite to the support surface. The ESC has an adsorption electrode and one or more resistive heaters disposed in the ESC. The ESC base assembly is coupled to the ESC, and the ESC base assembly has a base channel disposed in the ESC base assembly. The base channel has a base inlet that is fluidly connected to a jacketed base inlet tube disposed through a facility plate, an insulator plate coupled to the facility plate, and a ground plate coupled to the insulator plate. The base channel has a base outlet that is fluidly connected to a jacketed base outlet tube disposed through the facility plate, the insulator plate, and the ground plate. The facility plate includes a plate portion and a wall portion. The plate portion is coupled to the ESC base assembly using one or more first screw assemblies, and the wall portion is coupled to the ESC using a sealing assembly. The facility plate has a facility channel disposed in the facility plate. The sealing assembly includes a polytetrafluoroethylene (PTFE) body, and the polytetrafluoroethylene (PTFE) body has a coil spring disposed in the polytetrafluoroethylene (PTFE) body. The vacuum region is defined by the ESC, the ESC base assembly, the plate portion of the facility plate, the wall portion of the facility plate, and the seal assembly.

[0009] In yet another embodiment, a processing chamber is provided. The processing chamber includes: a chamber body having walls and a lid defining a processing region. A substrate support assembly is disposed in the processing region. The substrate support assembly includes: an electrostatic chuck (ESC) having a support surface and a bottom surface opposite the support surface. The ESC has an adsorption electrode and one or more resistive heaters disposed in the ESC. The ESC base assembly is coupled to the ESC, the ESC base assembly having a base channel disposed in the ESC base assembly. The facility plate has a facility channel disposed in the facility plate. The facility plate includes a plate portion and a wall portion. The plate portion is coupled to the ESC base assembly and the wall portion is coupled to the ESC using a sealing assembly. A vacuum region is defined by the ESC, the ESC base assembly, a plate portion of the facility plate, a wall portion of the facility plate, and a sealing assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order that the manner in which the above-mentioned features of the present disclosure can be understood in detail, a more specific description of the present disclosure briefly summarized above can be obtained by reference to embodiments, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate exemplary embodiments and therefore should not be considered as limiting the scope thereof, and other equivalent embodiments may be allowed.

[0011] Figure 1 is a schematic cross-sectional view of an exemplary plasma processing chamber according to an embodiment.

[0012] Figure 2A and Figure 2B is a cross-sectional schematic diagram of an exemplary substrate support assembly according to an embodiment.

[0013] Figure 2C is a schematic diagram of a screw assembly according to an embodiment.

[0014] Figure 3 is a schematic diagram of a sealing assembly according to an embodiment.

[0015] Figure 4A-4D is a schematic cross-sectional view of an ESC base assembly according to an embodiment.

[0016] Figure 4E is a schematic cross-sectional view of a peripheral portion of an exemplary substrate support assembly according to an embodiment.

[0017] Figure 5A-5C is a cross-sectional schematic diagram of an exemplary substrate support assembly according to an embodiment.

[0018] Figure 5D is a schematic cross-sectional view of a cryogenic optical probe assembly according to an embodiment.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. DETAILED DESCRIPTION

[0020] Embodiments described herein provide a substrate support assembly that enables cryogenic operation of an electrostatic chuck (ESC) such that a substrate disposed on the electrostatic chuck (ESC) is maintained at a cryogenic processing temperature suitable for processing while other surfaces of the processing chamber are maintained at different temperatures. Cryogenic processing temperatures (i.e., substrate temperatures) are intended to refer to temperatures below -20 degrees Celsius.

[0021] Although the substrate support assembly is described below in the context of an etch processing chamber, the substrate support assembly may be used in other types of plasma processing chambers (such as physical vapor deposition chambers, chemical vapor deposition chambers, ion implantation chambers, etc.) and other systems where processing requires maintaining a substrate at cryogenic processing temperatures.

[0022] Figure 11 is a cross-sectional schematic diagram of an exemplary plasma processing chamber 100 configured as an etching chamber having a substrate support assembly 101. The substrate support assembly 101 can be used in other types of plasma processing chambers (e.g., plasma processing chambers, annealing chambers, physical vapor deposition chambers, chemical vapor deposition chambers, and ion implantation chambers, etc.) and other systems where the ability to uniformly maintain a surface or workpiece (such as a substrate 124) at a cryogenic processing temperature is desired. Dry reactive ion etching of a substrate 124 maintained at a cryogenic processing temperature enables ions to bombard an upwardly facing surface of a material disposed on the substrate 124 with reduced spontaneous etching, thereby forming a groove with smooth, vertical sidewalls. For example, diffusion of ions in pores of a low-k dielectric material disposed on a substrate 124 uniformly maintained at a cryogenic processing temperature is reduced while the ions continue to bombard the upwardly facing surface of the low-k dielectric material to form a groove with smooth, vertical sidewalls. In addition, at cryogenic processing temperatures, the selectivity of etching one material relative to another can be improved. For example, as the temperature decreases, the selectivity between silicon (Si) and silicon dioxide (SiO2) increases exponentially.

[0023] The plasma processing chamber 100 includes a chamber body 102 having sidewalls 104, a bottom 106, and a lid 108 to enclose a processing region 110. An injection device 112 is coupled to the sidewalls 104 and / or the lid 108 of the chamber body 102. A gas panel 114 is coupled to the injection device 112 to allow process gases to be provided into the processing region 110. The injection device 112 may be one or more nozzles or inlet ports, or alternatively a showerhead. The process gases and any process byproducts are removed from the processing region 110 through an exhaust port 116 formed in the sidewalls 104 or the bottom 106 of the chamber body 102. The exhaust port 116 is coupled to a pumping system 140, which includes a throttle valve and a pump for controlling the vacuum level within the processing region 110.

[0024] The process gas may be excited to form a plasma within the processing region 110. The process gas may be excited by capacitively or inductively coupling RF power to the process gas. In embodiments that may be combined with other embodiments described herein, such as Figure 1 As depicted, a plurality of coils 118 are disposed above a lid 108 of a plasma processing chamber 100 and are coupled to an RF power source 122 through a matching circuit 120 .

[0025] The substrate support assembly 101 is disposed in the processing region 110 below the injection device 112. The substrate support assembly 101 includes an ESC 103 and an ESC base assembly 105. The ESC base assembly 105 is coupled to the ESC 103 and a facility plate 107. The facility plate 107 supported by a ground plate 111 is configured to facilitate electrical, cooling, heating, and gas connections to the substrate support assembly 101. The ground plate 111 is supported by the bottom 106 of the processing chamber. An insulator plate 109 insulates the facility plate 107 from the ground plate 111.

[0026] The ESC base assembly 105 includes a base channel 416 coupled to the cryocooler 117 (at Figure 4A-4D In one embodiment that may be combined with other embodiments described herein, the cryocooler 117 is connected to the base channel 416 via an inlet 254 (in Figure 2A and Figure 2B The base inlet conduit 123 (shown in FIG. 1 ) and the outlet 256 (shown in FIG. 1 ) connected to the base passage 416 via the Figure 2A and Figure 2B 105 is connected to the base outlet conduit 125 of the ESC base assembly 105 (shown in FIG. 106 ) and the base channel 416 fluid is connected to the ESC base assembly 105 so that the ESC base assembly 105 is maintained at a predetermined low temperature. In one embodiment that can be combined with other embodiments described herein, a cryocooler 117 is coupled to the interface box to control the flow rate of the base fluid. The base fluid may contain a material that can maintain a low temperature below -50 degrees Celsius. The cryocooler 117 provides a base fluid that circulates through the base channel 416 of the ESC base assembly 105. The base fluid flowing through the base channel 416 enables the ESC base assembly 105 to be maintained at a low temperature, which helps to control the lateral temperature distribution of the ESC 103 so that the substrate 124 disposed on the ESC 103 is uniformly maintained at a low temperature processing temperature. In one embodiment that can be combined with other embodiments described herein, the cryocooler 117 is a single-stage cooler that is operable to maintain a low temperature below about -50 degrees Celsius. In another embodiment, which may be combined with other embodiments described herein, the cryocooler 117 is a two-stage cooler that utilizes a refrigerant inside the two-stage cooler such that the base fluid is maintained at a low temperature of less than -50 degrees Celsius.

[0027] The facility plate 107 includes a facility channel 234 coupled to the cooler 119 (at Figure 2A and Figure 2B ). The cooler 119 is connected to the utility channel 234 via an inlet 240 (at Figure 2A and Figure 2B ) and via an outlet 242 (shown in Figure 2A and Figure 2B107) is in fluid communication with the facility channel 234 so that the facility plate 107 is maintained at a predetermined ambient temperature. In one embodiment that may be combined with other embodiments described herein, a cryocooler 117 is coupled to the interface box to control the flow rate of the facility fluid. The facility fluid may include a material that can maintain an ambient temperature between about -10 degrees Celsius and about 60 degrees Celsius. The cooler 119 provides a facility fluid that circulates through the facility channel 234 of the facility plate 107. The facility fluid flowing through the facility channel 234 enables the facility plate 107 to be maintained at a predetermined ambient temperature, which helps maintain the insulator plate 109 at a predetermined ambient temperature.

[0028] The ESC 103 has a support surface 130 and a bottom surface 132 opposite the support surface 130. In one embodiment, which may be combined with other embodiments described herein, the ESC 103 is made of a ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN), or other suitable materials. Alternatively, the ESC 103 may be made of a polymer such as polyimide, polyetheretherketone, polyaryletherketone, etc.

[0029] The ESC 103 includes an adsorption electrode 126 disposed in the ESC 103. The adsorption electrode 126 can be configured as a monopolar or bipolar electrode, or other suitable arrangement. The adsorption electrode 126 is coupled to an adsorption power supply 134 through an RF filter and a facility board 107, and the adsorption power supply 134 provides DC power to electrostatically fix the substrate 124 to the support surface 130 of the ESC 103. The RF filter prevents the RF power used to form a plasma (not shown) within the plasma processing chamber 100 from damaging electrical equipment or causing electrical hazards outside the chamber.

[0030] The ESC 103 includes one or more resistive heaters 128 embedded in the ESC 103. The resistive heaters 128 are used to raise the temperature of the ESC 103 to a cryogenic processing temperature suitable for processing a substrate 124 disposed on a support surface 130. The resistive heaters 128 are coupled to a heater power supply 136 through a facility board 107 and an RF filter. The RF filter prevents RF power used to form a plasma (not shown) within the plasma processing chamber 100 from damaging electrical equipment or causing electrical hazards outside the chamber. The heater power supply 136 can provide 500 watts or more of power to the resistive heaters 128. The heater power supply 136 includes a controller (not shown) for controlling the operation of the heater power supply 136, which is generally set to heat the substrate 124 to a predetermined cryogenic temperature. In one embodiment that may be combined with other embodiments described herein, the resistive heater 128 includes a plurality of laterally separated heating zones, wherein the controller enables at least one zone of the resistive heater 128 to be preferentially heated relative to the resistive heaters 128 in one or more zones in the other zones. For example, the resistive heaters 128 may be concentrically arranged in a plurality of separate heating zones. The resistive heaters 128 maintain the substrate 124 at a cryogenic processing temperature suitable for processing. In one embodiment that may be combined with other embodiments described herein, the cryogenic processing temperature is less than about -20 degrees Celsius. For example, the cryogenic processing temperature is between about -20 degrees Celsius and about -150 degrees Celsius.

[0031] The substrate support assembly 101 may include one or more probes disposed in the substrate support assembly 101. In one embodiment, which may be combined with other embodiments described herein, one or more cryogenic optical probe assemblies 500 (in Figure 5A-5D ) is coupled to the probe controller 138. In one embodiment that may be combined with other embodiments described herein, the probe tip 516 of each of the cryogenic optical probes 512 is disposed in the surface of the ESC 103 (eg, Figure 5B ) or at the surface of the ESC 103 (as shown in Figure 5A ) to determine the temperature of the ESC 103. In another embodiment that may be combined with other embodiments described herein, the probe tip 516 of each of the cryogenic optical probes 512 is disposed in the ESC base assembly 105 (as shown in Figure 5C) to calibrate the temperature of the substrate based on the temperature of the ESC base assembly 105. In one embodiment that may be combined with other embodiments described herein, each of the cryogenic optical probe assemblies 500 corresponds to a zone of a plurality of laterally separated heating zones of the resistive heater 128, wherein the cryogenic optical probe 512 measures the temperature of each zone of the ESC 103. The probe controller 138 is coupled to the heater power supply 136 so that each zone of the resistive heater 128 is independently heated based on the temperature measurement value to make the lateral temperature distribution of the ESC 103 substantially uniform, so that the substrate 124 disposed on the ESC 103 is uniformly maintained at the cryogenic processing temperature.

[0032] Figure 2A and Figure 2B 1 is a cross-sectional schematic diagram of an exemplary substrate support assembly 101 that enables cryogenic operation of an ESC 103 such that a substrate 124 disposed on the ESC 103 is maintained at a cryogenic processing temperature. The ESC 103 is coupled to an ESC base assembly 105. In one embodiment that may be combined with other embodiments described herein, a bonding layer 202 is used to secure the ESC 103 to the ESC base assembly 105. The bonding layer 202 may include an organic or inorganic material. In some embodiments that may be combined with other embodiments described herein, the bonding layer 202 may include an epoxy or a metallic material. The adsorption electrode 126 is coupled to the adsorption power source 134 via a first insulating wire 204 that is disposed through a first hole 208 in a lower insulator 212 of the facility plate 107 and an upper insulator 214 of the ESC base assembly 105. The one or more resistive heaters 128 are coupled to the heater power supply 136 via a second insulated wire 206 disposed through a second hole 210 in a lower insulator 212 of the facility plate 107 and an upper insulator 214 of the ESC base assembly 105 .

[0033] The facility plate 107 includes a plate portion 229 and a wall portion 230. The plate portion 229 of the facility plate 107 is coupled to the ESC base assembly 105 using one or more first screw assemblies 220 such that a vacuum region 222 exists between the ESC base assembly 105 and the facility plate 107. Each of the one or more first screw assemblies 220 includes a bolt 224 that passes through a thermal break 227 in contact with the facility plate 107, one or more Belleville washers 226, and the facility plate 107 and is inserted into a threaded hole 228 of the ESC base assembly 105. The thermal break 227 is in contact with the facility plate 107 to provide thermal isolation from the ESC base assembly 105, which is maintained at a low temperature. In one embodiment that may be combined with other embodiments described herein, the thermal break 227 includes a material containing polyamide-imide (PAI) or polyimide (PI). One or more Belleville spring washers 226 and bolts 224 are preloaded so that the facility plate 107 is forced against the ESC base assembly 105. In some embodiments, as Figure 2C As shown in FIG, the screw cover 261 is coupled to the facility plate 107 over the bolt 224 so that a vacuum insulation region 263 is maintained between each of the one or more first screw assemblies 220. The screw cover 261 is coupled to the facility plate 107 via an O-ring 267 to maintain pressure in the vacuum insulation region 263 and to thermally insulate each of the one or more first screw assemblies 220 from the facility plate 107.

[0034] The facility plate 107 includes a wall portion 230 coupled to the ESC 103 by a sealing assembly 232. In one embodiment that may be combined with other embodiments described herein, the lower insulator 212 of the facility plate 107 maintains a vacuum region 222 via the sealing assembly 232. The wall coupled to the ESC 103 by the sealing assembly 232 protects the material of the ESC base assembly 105 from potential contact with process gases and peeling. The vacuum region 222 is defined by the ESC 103, the ESC base assembly 105, the facility plate 107, and the sealing assembly 232. The vacuum region 222 prevents condensation on the back side of the cooling plate, prevents process gases from entering the substrate support assembly 101 by having a pressure independent of the pressure of the processing area 110, and provides thermal isolation between the ESC base assembly 105 and the facility plate 107. In one embodiment that may be combined with other embodiments described herein, the facility plate 107 includes an aluminum-containing material.

[0035] The facility channel 234 of the facility plate 107 is machined in the facility plate 107 and welded to the cover 238. The inlet 240 of the facility channel 234 is in fluid communication with an inlet pipe 244 disposed through the insulator plate 109 and the ground plate 111. The outlet 242 of the facility channel 234 is in fluid communication with an outlet pipe 246 disposed through the insulator plate 109 and the ground plate 111. The inlet pipe 244 and the outlet pipe 246 are connected to a connection 248 having a connection inlet 250 connected to the facility inlet pipe 127 and a connection outlet 252 connected to the facility outlet pipe 129. In one embodiment that may be combined with other embodiments described herein, the connection 248, the inlet pipe 244, and the outlet pipe 246 may include an insulating material, such as a material containing ceramic.

[0036] exist Figure 4A-4D The base channel 416 of the ESC base assembly 105, which is described in more detail in FIG. 1 , includes an inlet 254 of the base channel 416, which is in fluid communication with a jacketed inlet tube 258 disposed through the facility plate 107, the insulator plate 109, and the ground plate 111. The outlet 256 of the base channel 416 is in fluid communication with a jacketed outlet tube 260 disposed through the facility plate 107, the insulator plate 109, and the ground plate 111. The jacketed inlet tube 258 and the jacketed outlet tube 260 are connected to the interface block 270. In one embodiment that may be combined with other embodiments described herein, the interface block 270, the jacketed inlet tube 258, and the jacketed outlet tube 260 include an insulating material, such as a material containing ceramic. The jacketed inlet tube 258 includes a fluid inlet channel 266 and a vacuum channel 262. The jacketed outlet tube 260 includes a fluid outlet channel 268 and a vacuum channel 264. The interface block 270 includes a base inlet 272, a vacuum channel 276, a base outlet 274, and a vacuum channel 278. The base inlet 272 is connected to the base inlet conduit 123, and the base outlet 274 is connected to the base outlet conduit 125. The vacuum channel 276 is connected to a vacuum conduit 280 in fluid communication with a vacuum source 284, and the vacuum channel 278 is connected to a vacuum conduit 282 in fluid communication with the vacuum source 284. Coupling the vacuum source 284 to the vacuum region 222 enables a pressure to be maintained in the vacuum region 222 that is independent of the pressure of the processing region 110. In one embodiment that may be combined with other embodiments described herein, the fluid inlet channel 266 and the fluid outlet channel 268 are coupled to the ESC base assembly 105 through the seal assembly 232 to maintain the pressure in the vacuum region 222.

[0037] The substrate support assembly 101 also includes one or more lift pin assemblies 286 for accommodating lift pins (not shown) for raising the substrate 124 above the support surface 130 of the ESC 103 to facilitate automated transfer in and out of the plasma processing chamber 100. Each of the one or more lift pin assemblies 286 includes a lift pin guide 288 disposed through the ESC 103, the ESC base assembly 105, the facility plate 107, the insulator plate 109, and the ground plate 111. A portion 290 of the lift pin guide 288 disposed through the ESC base assembly 105 is surrounded by a threaded bushing 292 that holds the lift pin guide 288 in place. The lift pin guide 288 is coupled to the ESC 103 through a seal assembly 232 to maintain the chamber vacuum and the insulating vacuum separate. In one embodiment, which may be combined with other embodiments described herein, the ESC 103 includes one or more gas passages for providing a backside heat transfer gas, such as helium, to the interstitial space defined between the substrate 124 and the support surface 130 of the ESC 103. Each of the one or more gas passages is disposed through the ESC 103, the ESC base assembly 105, the facility plate 107, the insulator plate 109, and the ground plate 111. Each of the one or more gas passages is coupled to the ESC 103 through a sealing assembly 232 to maintain the pressure in the vacuum region 222.

[0038] like Figure 2B , the facility plate 107 includes a recessed portion 296 and a seal 294 disposed between the insulator plate 109 and the facility plate 107. A surface 205 of the insulator plate 109 coupled to the facility plate 107 is conformal with the facility plate 107. The recessed portion 296 and the insulator plate 109 provide a reduced thickness 201 of the facility plate 107 and an increased thickness 203 of the insulator plate 109. The reduced thickness 201 of the facility plate 107 and the increased thickness 203 of the insulator plate 109 reduce the length of the first insulating wire 204 disposed through the first hole 208 in the lower insulator 212 of the facility plate 107 and the length of the first insulating wire 204 disposed through the insulator plate 109. Reducing the length of the first insulating wire 204 disposed through the first hole 208 reduces an arc potential in the first hole 208 of the RF heat facility plate 107 from a voltage provided to the first insulating wire 204 by the adsorption power source 134. In one embodiment, which may be combined with other embodiments described herein, the outer portion 269 of the insulator plate 109 includes a material that is different from the material of the inner portion 271 of the insulator plate 109. The outer portion 269 may include a material including aluminum oxide (AlO2), and the inner portion 271 of the insulator plate 109 may include a material including polystyrene.

[0039] Figure 3 is a schematic diagram of a seal assembly 232 according to an embodiment. Figure 3 The seal assembly 232 is shown as a face seal, and the embodiments described herein may include a piston (i.e., radial) seal or a metal seal having a polytetrafluoroethylene (PTFE) body. The seals described herein provide for sealing the vacuum region 222 at temperatures between about -260 degrees Celsius and about 290 degrees Celsius. Figure 3 , the sealing assembly 232 comprises a PTFE body 302 having a spring 304 disposed therein. In one embodiment that may be combined with other embodiments described herein, the spring 304 comprises a material comprising stainless steel, a nickel alloy, a nickel-chromium alloy, and a cobalt-chromium-nickel-molybdenum alloy. The sealing assembly 232 allows the ESC 103 to be sealed at low temperatures. The PTFE body 302 having a spring disposed therein may be operated at a temperature between about -260 degrees Celsius and about 290 degrees Celsius.

[0040] Figure 4A and Figure 4B is a cross-sectional schematic diagram of an ESC base assembly 105 having an ESC base 402 coupled to a base channel plate 404. The ESC base 402 comprises a material that substantially matches the coefficient of thermal expansion of the ESC 103. The ESC base 402 may comprise a material comprising molybdenum or carbon fiber. In one embodiment that may be combined with other embodiments described herein, the base channel plate 404 is comprised of an aluminum-containing material. The base channel plate 404 comprises a base channel 416 of the ESC base assembly 105. The base channel 416 is machined in the base channel plate 404 and joined, welded, or brazed to a cover 420. The inlet 254 of the base channel 416 is in fluid communication with a jacketed inlet tube 258, and the outlet 256 of the base channel 416 is in fluid communication with a jacketed outlet tube 260. The ESC base 402 is coupled to the base channel plate 404 via one or more second screw assemblies 408. In one embodiment, as Figure 4A As shown in FIG. 4 , the ESC base 402 is coupled to the base channel plate 404 using a thermally conductive pad 406 between the ESC base 402 and the base channel plate 404 to maintain a defined thermal conductivity between the ESC base 402 and the base channel plate 404. In another embodiment, as shown in FIG. Figure 4B , the thermally conductive pad 406 is not included. Each of the one or more second screw assemblies 408 includes a bolt 410 that passes through one or more Belleville spring washers 412 and the ESC base 402 and is inserted into a threaded hole 414 of the ESC base 402. The one or more Belleville spring washers 412 and the bolts 410 are preloaded so that the base channel plate 404 is forced against the ESC base 402.

[0041] Figure 4C4 is a cross-sectional schematic diagram of an ESC base assembly 105 having an ESC base 402 having a base channel 416. The ESC base 402 comprises a material comprising molybdenum or carbon fiber to substantially match the coefficient of thermal expansion of the ESC 103. The base channel 416 is machined in the ESC base 402 and bonded, welded, or brazed to the cover 420. The inlet 254 of the base channel 416 is in fluid communication with the jacketed inlet tube 258, and the outlet 256 of the base channel 416 is in fluid communication with the jacketed outlet tube 260.

[0042] Figure 4D is a cross-sectional schematic diagram of an ESC base assembly 105 having an ESC base 402 having a base channel 416. The ESC base 402 comprises a material comprising molybdenum or carbon fiber to substantially match the coefficient of thermal expansion of the ESC 103. The base channel 416 is a coil disposed in a space 424 machined in the ESC base 402. The inlet 254 of the base channel 416 is in fluid communication with the jacketed inlet tube 258, and the outlet 256 of the base channel 416 is in fluid communication with the jacketed outlet tube 260.

[0043] Figure 4E yes Figure 2B Schematic diagram of a cross-sectional view of a peripheral portion of the substrate support assembly 101 of FIG. The ESC base 402 includes a recess 426 exposed to the vacuum region 222. The recess 426 includes an RF gasket 428 disposed in the recess 426. The plate portion 229 of the facility plate 107 includes a recess 430 having an RF gasket 432 disposed in the recess 430. When the ESC base 402 and the base channel plate 404 are thermally isolated from the facility plate 107, the RF gasket 432 maintains RF connectivity between the base channel plate 404 and the facility plate 107. Similarly, when the ESC base 402 and the base channel plate 404 are thermally isolated from the facility plate 107, the RF gasket 432 maintains RF connectivity between the base channel plate 404 and the facility plate 107. Figure 4A and Figure 4E While the thermally conductive gasket 406 in the embodiment shown in FIG. 4 is thermally conductive, the RF gasket 428 maintains electrical RF connectivity between the base channel plate 404 and the ESC base 402 .

[0044] Figure 5A-5C is a cryogenic optical probe assembly 500 (in Figure 5D107 . A schematic cross-sectional view of an exemplary substrate support assembly 101 of an optical probe assembly 500 is shown in FIG. 10 . Each of the cryogenic optical probe assemblies 500 includes an optical fiber 510 connected to a probe controller 138. Each of the cryogenic optical probe assemblies 500 includes a mounting housing 502 disposed in an insulator plate 109 and a probe housing 504 disposed in the insulator plate 109 and the facility plate 107. The mounting housing 502 is coupled to the probe housing 504 using a probe mounting bolt 506 that passes through the mounting housing 502 and is inserted into a threaded hole 508 of the insulator plate 109, thereby forcing the probe assembly 500 against the facility plate 107. The optical fiber 510 is connected to a cryogenic optical probe 512 disposed in the probe housing 504. The probe housing 504 includes a spring 514 to provide vertical movement for the cryogenic optical probe 512 so that a probe tip 516 of the cryogenic optical probe 512 is configured to contact the ESC 103. In one embodiment that may be combined with other embodiments described herein, the probe tip 516 contacts the ESC 103 without penetrating the surface. In another embodiment that may be combined with other embodiments described herein, Figure 5B , the probe tip 516 is disposed within the ESC 103. In the facility board 107, a threaded cap 518 surrounds the probe housing 504. An inner portion 520 of the threaded cap 518 is coupled to the probe housing 504 using an inner seal 522. The inner seal 522 allows the probe tip 516 to maintain contact with the ESC 103. In one embodiment that may be combined with other embodiments described herein, the inner seal 522 is a seal assembly 232. In another embodiment that may be combined with other embodiments described herein, the inner seal 522 is an elastomeric seal. In yet another embodiment that may be combined with other embodiments described herein, the inner seal 522 is an O-ring. An outer portion 524 of the threaded cap 518 is coupled to the facility board 107 using an outer seal 526. The outer seal 526 seals the probe housing 504 from the vacuum region 222. In one embodiment that may be combined with other embodiments described herein, the outer seal 526 is an O-ring.

[0045] In summary, a substrate support assembly is provided that enables cryogenic operation of an ESC, such that a substrate disposed on the ESC is maintained at a cryogenic processing temperature while maintaining other surfaces of the processing chamber at different temperatures. The substrate support assembly is disposed in a processing chamber and includes an ESC 103, an ESC base assembly 105 coupled to the ESC 103 and a facility plate 107, and an insulator plate 109 coupled to a ground plate 111. A base fluid flowing through a base channel 416 of the ESC base assembly 105 coupled to the ESC 103 in combination with a resistive heater 128 enables the ESC base assembly 105 to be maintained at a predetermined low temperature, which helps control the lateral temperature distribution of the ESC 103, such that a substrate 124 disposed on the ESC 103 is uniformly maintained at a cryogenic processing temperature. A facility fluid flowing through a facility channel 234 of the facility plate 107 enables the facility plate 107 to be maintained at an ambient temperature, which helps maintain the insulator plate 109 and the ground plate 111 at an ambient temperature.

[0046] While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope thereof, and the scope of the disclosure is determined by the claims that follow.

Claims

1. A substrate support assembly, comprising: an electrostatic chuck having a support surface and a bottom surface opposite to the support surface, the electrostatic chuck having an adsorption electrode and one or more resistive heaters disposed in the electrostatic chuck; an electrostatic chuck base assembly coupled to the electrostatic chuck, the electrostatic chuck base assembly having a base channel disposed therein; a facility plate having a facility channel disposed therein, the facility plate comprising a plate portion and a wall portion, the plate portion coupled to the electrostatic chuck base assembly and the wall portion coupled to the electrostatic chuck using a sealing assembly; as well as a vacuum region defined by the electrostatic chuck, the electrostatic chuck base assembly, the plate portion of the facility plate, the wall portion of the facility plate, and the sealing assembly, wherein the vacuum region always maintains a gap between the electrostatic chuck base assembly and the plate portion of the facility plate.

2. The substrate support assembly of claim 1, further comprising an insulator plate coupled to the facility plate and a ground plate coupled to the insulator plate.

3. The substrate support assembly of claim 1, wherein the electrostatic chuck base assembly is secured to the electrostatic chuck using a bonding layer.

4. The substrate support assembly of claim 1, wherein the electrostatic chuck comprises a material comprising aluminum oxide (Al2O3) and / or aluminum nitride (AlN).

5. The substrate support assembly of claim 1 , wherein the pedestal channel has an inlet and an outlet, the pedestal channel being operably connected to a cryocooler in fluid communication with the pedestal channel via a pedestal inlet conduit connected to the inlet of the pedestal channel and a pedestal outlet conduit connected to the outlet of the pedestal channel.

6. The substrate support assembly of claim 1 , wherein the facility channel has an inlet and an outlet, the facility channel being operably connected to a cooler in fluid communication with the facility channel via a facility inlet conduit connected to the inlet of the facility channel and a facility outlet conduit connected to the outlet of the facility channel.

7. The substrate support assembly of claim 1 , wherein the vacuum region comprises a first vacuum channel and a second vacuum channel, the first vacuum channel being operable to connect to a first vacuum conduit in fluid communication with a vacuum source and the second vacuum channel being operable to connect to a second vacuum conduit in fluid communication with the vacuum source to maintain a vacuum pressure in the vacuum region independent of a pressure in a processing region of the processing chamber.

8. The substrate support assembly of claim 1, further comprising one or more probe assemblies coupled to a probe controller, each of the one or more probe assemblies comprising a probe tip.

9. The substrate support assembly of claim 8, wherein a heater power supply for the one or more resistive heaters is connected to the probe controller, the heater power supply having a controller.

10. The substrate support assembly of claim 1, wherein the sealing assembly comprises a polytetrafluoroethylene (PTFE) body having a coil spring disposed therein to seal the vacuum region at a temperature between about -260 degrees Celsius and about 290 degrees Celsius.

11. The substrate support assembly of claim 10, wherein the coil spring comprises a material including stainless steel, nickel alloy, nickel-chromium alloy, and cobalt-chromium-nickel-molybdenum alloy.

12. The substrate support assembly of claim 1, wherein: The base channel has a base inlet in fluid communication with a jacketed base inlet tube disposed through a facility plate, an insulator plate coupled to the facility plate, and a ground plate coupled to the insulator plate, the base channel having a base outlet in fluid communication with a jacketed base outlet tube disposed through the facility plate, the insulator plate, and the ground plate; and wherein: The seal assembly includes a polytetrafluoroethylene (PTFE) body having a coil spring disposed therein.

13. The substrate support assembly of claim 12, wherein the coil spring comprises a material including stainless steel, nickel alloy, nickel-chromium alloy, and cobalt-chromium-nickel-molybdenum alloy.

14. A processing chamber comprising: a chamber body having sidewalls and a cover defining a processing area; A substrate support assembly disposed in the processing area, the substrate support assembly comprising: an electrostatic chuck having a support surface and a bottom surface opposite to the support surface, the electrostatic chuck having an adsorption electrode and one or more resistive heaters disposed in the electrostatic chuck; an electrostatic chuck base assembly coupled to the electrostatic chuck, the electrostatic chuck base assembly having a base channel disposed therein; a facility plate having a facility channel disposed therein, the facility plate comprising a plate portion and a wall portion, the plate portion coupled to the electrostatic chuck base assembly and the wall portion coupled to the electrostatic chuck using a sealing assembly; and a vacuum region defined by the electrostatic chuck, the electrostatic chuck base assembly, the plate portion of the facility plate, the wall portion of the facility plate, and the sealing assembly, wherein the vacuum region always maintains a gap between the electrostatic chuck base assembly and the plate portion of the facility plate.

15. The processing chamber of claim 14, further comprising an insulator plate coupled to the facility plate and a ground plate coupled to the insulator plate.

16. The processing chamber of claim 14, wherein the electrostatic chuck comprises a material comprising aluminum oxide (Al2O3) and / or aluminum nitride (AlN).

17. The processing chamber of claim 14, wherein the electrostatic chuck base assembly comprises a material comprising molybdenum or carbon fiber.

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