Electrostatic chuck for high bias radio frequency (RF) power application in plasma processing chambers

Abstract

Embodiments of electrostatic chucks are provided herein. In some embodiments, an electrostatic chuck for use in a substrate processing chamber includes: a plate having a first side and a second side opposite the first side; a first electrode embedded in the plate near the first side; a second electrode embedded in the plate near the second side; a plurality of conductive elements coupling the first electrode to the second electrode; a first gas channel disposed in the plate and between the first electrode and the second electrode; a gas inlet extending from the second side of the plate to the first gas channel; and a plurality of gas outlets extending from the first side of the plate to the first gas channel.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to substrate processing systems and, more particularly, to electrostatic chucks for use in substrate processing systems. Background Art

[0002] Radio frequency (RF) power is commonly used in etching processes, such as those that require very high aspect ratio holes for contact or deep trenches for laying electrical path infrastructure. RF power can be used to generate plasma and / or establish a bias on the substrate to be processed to attract ions from the overall plasma. An electrostatic chuck is used to electrostatically hold the substrate to control the substrate temperature during processing. An electrostatic chuck typically includes an electrode embedded in a dielectric plate and a cooling plate disposed below the dielectric plate. An RF power source for establishing the bias is applied to the cooling plate. A backside gas can be introduced between the substrate and the electrostatic chuck via a gas channel in the electrostatic chuck as a heat transfer medium. However, the inventors have observed that the RF power applied to the cooling plate to induce a bias on the substrate establishes a DC potential difference between the substrate and the cooling plate, which may undesirably cause arcing in the gas channel.

[0003] Accordingly, the inventors have provided an improved electrostatic chuck. Summary of the invention

[0004] Embodiments of electrostatic chucks are provided herein. In some embodiments, an electrostatic chuck for use in a substrate processing chamber includes: a plate having a first side and a second side opposite the first side; a first electrode embedded in the plate near the first side; a second electrode embedded in the plate near the second side; a plurality of conductive elements coupling the first electrode to the second electrode; a first gas channel disposed in the plate and between the first electrode and the second electrode; a gas inlet extending from the second side of the plate to the first gas channel; and a plurality of gas outlets extending from the first side of the plate to the first gas channel.

[0005] In some embodiments, an electrostatic chuck for use in a substrate processing chamber includes: a plate having a first side and a second side opposite the first side; a first electrode embedded in the plate near the first side; a second electrode embedded in the plate near the second side; a third electrode embedded in a peripheral area of ​​the plate between the first electrode and the second electrode; and a plurality of first posts extending from the first electrode to the second electrode to electrically couple the first electrode and the second electrode; and a plurality of second posts extending from at least one of the first electrode or the second electrode to the third electrode to electrically couple the third electrode to at least one of the first electrode or the second electrode.

[0006] In some embodiments, a process chamber includes: a chamber body having a substrate support disposed within an interior space of the chamber body, wherein the substrate support includes an electrostatic chuck, the electrostatic chuck including: a cooling plate; a dielectric plate disposed above the cooling plate and having a first electrode, a second electrode, and a plurality of posts electrically coupling the first electrode to the second electrode; one or more first gas channels extending from a bottom surface of the electrostatic chuck to the dielectric plate; a plurality of second gas channels extending horizontally from the one or more first gas channels across the electrostatic chuck, between the first electrode and the second electrode; and a plurality of third gas channels extending from the plurality of second gas channels to a top surface of the electrostatic chuck.

[0007] Other and further embodiments of the present disclosure are described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The embodiments of the present disclosure briefly summarized above and discussed in more detail below may be understood by reference to the illustrated embodiments of the present disclosure depicted in the accompanying drawings. However, the accompanying drawings only illustrate typical embodiments of the present disclosure and therefore should not be considered as limiting the scope, as the present disclosure may allow other equally effective embodiments.

[0009] Figure 1 A schematic side view of a process chamber with an electrostatic chuck is depicted in accordance with at least some embodiments of the present disclosure.

[0010] Figure 2 A schematic partial side view of an electrostatic chuck is depicted in accordance with at least some embodiments of the present disclosure.

[0011] Figure 3 A schematic side view of an electrostatic chuck is depicted in accordance with at least some embodiments of the present disclosure.

[0012] Figure 4 A cross-sectional top view of an electrostatic chuck is depicted in accordance with at least some embodiments of the present disclosure.

[0013] To facilitate understanding, the same reference numerals have been used as much as possible to represent the same elements common to the drawings. The drawings are not drawn to scale and may be omitted for clarity. Elements and features of one embodiment may be beneficially incorporated into other embodiments without further description. DETAILED DESCRIPTION

[0014] Embodiments of an electrostatic chuck for use in a substrate processing chamber are provided herein. The electrostatic chuck includes a dielectric plate having a support surface to support a substrate. The dielectric plate is disposed on a cooling plate. In some embodiments, one or more gas channels extend from a bottom surface of the electrostatic chuck (e.g., a bottom surface of the cooling plate) to a top surface of the electrostatic chuck (e.g., a top surface of the dielectric plate). The one or more gas channels are configured to provide a backside gas, such as nitrogen (N) or helium (He), to the top surface of the electrostatic chuck to act as a heat transfer medium.

[0015] In some embodiments, an RF power source is coupled to the cooling plate and configured to provide a negative bias voltage to the processed substrate. As RF power is applied to the cooling plate, the peak-to-peak voltage (Vpp) on the cooling plate and the Vpp on the substrate differ depending on the impedance of the dielectric plate. The difference in the respective peak-to-peak voltages establishes an electric field between the cooling plate and the substrate, which may undesirably cause backside gas ionization and thereby arcing. In some embodiments, multiple electrodes are provided in the dielectric plate to advantageously reduce the difference between the Vpp on the cooling plate and the Vpp on the substrate.

[0016] Figure 1 is a schematic cross-sectional view of a process chamber (e.g., a plasma processing chamber) according to some embodiments of the present disclosure. In some embodiments, the plasma processing chamber is an etch processing chamber. However, other types of processing chambers configured for different processes may also be used or modified for use with the embodiments of the electrostatic chuck described herein.

[0017] The chamber 100 is a vacuum chamber suitable for maintaining a sub-atmospheric pressure within a chamber interior 120 during substrate processing. The chamber 100 includes a chamber body 106 covered by a lid 104, which encloses a processing volume 119 located in an upper portion of the chamber interior 120. The chamber 100 may also include one or more shields 105 surrounding various chamber components to avoid undesirable reactions between these components and ionized process materials. The chamber body 106 and the lid 104 may be made of metal, such as aluminum. The chamber body 106 may be grounded by coupling to a ground 115.

[0018] The substrate support 124 is disposed within the chamber interior 120 to support and retain a substrate 122 such as a semiconductor wafer or other such substrate that can be retained electrostatically. The substrate support 124 may generally include an electrostatic chuck 150 (hereinafter referred to as Figures 2 to 41 and 13. The electrostatic chuck 150 includes a dielectric plate 152 having one or more electrodes 154 disposed therein and a cooling plate 136. The hollow support rod 112 provides a conduit to provide, for example, backside gas, process gas, fluid, coolant, etc. to the electrostatic chuck 150.

[0019] In some embodiments, hollow support rod 112 is coupled to a lifting mechanism 113, such as an actuator or a motor, to provide a position where electrostatic chuck 150 is in an upper, processing position (eg, Figure 1 1) and a lower, transfer position (not shown). Bellows assembly 110 is disposed about hollow support rod 112 and is coupled between electrostatic chuck 150 and bottom surface 126 of chamber 100 to provide a resilient seal to allow vertical movement of electrostatic chuck 150 while preventing vacuum leakage from within chamber 100. Bellows assembly 110 also includes a lower bellows flange 164 in contact with an o-ring 165 or other suitable sealing element in contact with lower surface 126 to help prevent leakage of chamber vacuum.

[0020] The hollow support rod 112 provides a conduit for coupling a backside gas supply 141, a chucking power supply 140, and an RF source (e.g., an RF plasma power supply 170 and an RF bias power supply 117) to the electrostatic chuck 150. In some embodiments, the RF energy supplied by the RF plasma power supply 170 may have a frequency of about 40 MHz or greater. The backside gas supply 141 is disposed outside the chamber body 106 and supplies a heat transfer gas to the electrostatic chuck 150. In some embodiments, the RF plasma power supply 170 and the RF bias power supply 117 are coupled to the electrostatic chuck 150 via respective RF matching networks (only the RF matching network 116 is shown). In some embodiments, the substrate support 124 may alternatively include an AC, DC, or RF bias power source.

[0021] The substrate lifter 130 may include lift pins 109 mounted on the platform 108, which is connected to rods 111, which are coupled to a second lift mechanism 132 for raising and lowering the substrate lifter 130 so that the substrate 122 can be placed on or removed from the electrostatic chuck 150. The electrostatic chuck 150 may include through holes to accommodate the lift pins 109. The bellows assembly 131 is coupled between the substrate lifter 130 and the bottom surface 126 to provide a resilient seal to maintain the chamber vacuum during the vertical movement of the substrate lifter 130.

[0022] The electrostatic chuck 150 includes a gas distribution channel 138 extending from a lower surface of the electrostatic chuck 150 to various openings in an upper surface of the electrostatic chuck 150. The gas distribution channel 138 is in fluid communication with a backside gas supply 141 via a gas conduit 142 to control the temperature and / or temperature profile of the electrostatic chuck 150 during use.

[0023] The chamber 100 is coupled to and in fluid communication with a vacuum system 114, which includes a throttle valve (not shown) and a vacuum pump (not shown) for evacuating the chamber 100. The pressure inside the chamber 100 can be adjusted by adjusting the throttle valve and / or the vacuum pump. The chamber 100 is also coupled to and in fluid communication with a process gas supply 118, which can supply one or more process gases to the chamber 100 for processing a substrate disposed therein.

[0024] For example, in operation, a plasma 102 may be established in the chamber interior 120 to perform one or more processes. The plasma 102 may be established by coupling power from a plasma power source (e.g., an RF plasma power supply 170) to a process gas via one or more electrodes near or within the chamber interior 120 to ignite the process gas and establish the plasma 102. Bias power may also be provided from a bias power supply (e.g., an RF bias power supply 117) to one or more electrodes 154 within the electrostatic chuck 150 to attract ions from the plasma toward the substrate 122.

[0025] Figure 2 A schematic partial side view of an electrostatic chuck 200 for use in chamber 100 is depicted in accordance with at least some embodiments of the present disclosure. Electrostatic chuck 200 may be used as described above with respect to Figure 1 The electrostatic chuck 150 is described. The electrostatic chuck 200 includes a dielectric plate 210 and a cooling plate 220. In some embodiments, the dielectric plate 210 is attached to the cooling plate 220 using an adhesive layer. In some embodiments, the dielectric plate 210 has a first side 202 and a second side 204 opposite to the first side 202. In some embodiments, the first side 202 corresponds to a support surface 232 of the electrostatic chuck 200. In some embodiments, the substrate 122 is disposed on the support surface 232. In some embodiments, the cooling plate 220 is made of a conductive material, such as aluminum (Al). In some embodiments, the cooling plate 220 includes a passage (not shown) to accommodate the flow of a coolant.

[0026] The first electrode 208 is embedded in the dielectric plate 210 near the first side 202. The second electrode 218 is embedded in the dielectric plate 210 near the second side 204. In some embodiments, the first electrode 208 and the second electrode 218 are substantially parallel. The first electrode 208 and the second electrode 218 may be disk-shaped or any other shape corresponding to the shape of the dielectric plate 210. A plurality of conductive elements 212 electrically couple the first electrode 208 to the second electrode 218. In some embodiments, the plurality of conductive elements 212 are a plurality of pillars. In some embodiments, a first distance 228 between the first electrode 208 and the first side 202 is about 0.8 mm to about 1.2 mm. In some embodiments, a second distance 230 between the second electrode 218 and the second side 204 is about 0.8 mm to about 1.2 mm. In some embodiments, the first distance 228 is substantially equal to the second distance 230. The first electrode 208, the second electrode 218, and the plurality of conductive elements 212 may be formed of suitable process compatible materials, such as molybdenum (Mo), titanium (Ti), etc.

[0027] Positioning the first electrode 208 proximate the first side 202 of the dielectric plate and the second electrode 218 proximate the second side 204, with the plurality of conductive elements 212 coupling the first electrode 208 to the second electrode 218, advantageously reduces the potential difference between the support surface 232 and the cooling plate 220 established as RF power passes through the dielectric plate 210. The reduced potential difference thus advantageously reduces arcing potential in the gas distribution channel 138.

[0028] In some embodiments, the gas distribution channel 138 includes one or more inlets disposed on a bottom surface of the electrostatic chuck (e.g., a bottom surface of a cooling plate). In some embodiments, the gas distribution channel 138 includes one or more outlets disposed on a support surface 232 or a top surface of the electrostatic chuck 200. In some embodiments, the gas distribution channel 138 extends from one or more inlets disposed on the bottom surface 214 of the electrostatic chuck 200 to one or more outlets disposed on the top surface of the electrostatic chuck 200. The gas distribution channel 138 is configured to provide a backside gas, such as nitrogen (N) or helium (He), to the top surface of the electrostatic chuck.

[0029] The region between the first electrode 208 and the second electrode 218 does not have an electric field. In some embodiments, the gas distribution channel 138 is substantially disposed between the first electrode 208 and the second electrode 218 to advantageously reduce or avoid the possibility of arcing therein. In some embodiments, the gas distribution channel 138 includes a first gas channel 222 disposed within the dielectric plate 210 and between the first electrode 208 and the second electrode 218. The location of the first gas channel 222 between the first electrode 208 and the second electrode 218 advantageously avoids arcing in the first gas channel 222. The first gas channel 222 is coupled to a gas inlet 224 disposed on the second side 204 of the dielectric plate 210. The first gas channel 222 is coupled to a plurality of gas outlets 226 disposed on the first side 202 of the dielectric plate 210. In some embodiments, the cross-sectional width of the first gas channel 222 is about 0.8 mm to about 1.2 mm. In some embodiments, the cross-sectional height of the first gas channel 222 is about 0.8 mm to about 1.2 mm.

[0030] In some embodiments, a porous plug 206 is disposed in the gas distribution channel 138 at the interface between the dielectric plate 210 and the cooling plate 220. In some embodiments, the porous plug 206 is made of aluminum. The porous plug 206 is configured to reduce or avoid the possibility of arcing of the backside gas at the interface between the dielectric plate 210 and the cooling plate 220.

[0031] Figure 3 A schematic side view of an electrostatic chuck is depicted in accordance with at least some embodiments of the present disclosure. A central connector 306 is coupled to a chucking power supply 140 and extends from a bottom surface 214 of the electrostatic chuck 200 into the dielectric plate 210. In some embodiments, the central connector 306 is directly coupled to the first electrode 208 to couple the chucking power supply 140 to the first electrode 208 to provide chucking power to the first electrode 208. In some embodiments, the central connector 306 is directly coupled to the second electrode 218. In some embodiments, an insulator 304 is disposed around the central connector 306 in the cooling plate 220 to electrically isolate the central connector 306 from the cooling plate 220.

[0032] In some embodiments, the edge ring 302 is disposed around the dielectric plate 210 to guide a substrate disposed on the dielectric plate 210. In some embodiments, the edge ring 302 is placed in a notch at an upper peripheral edge of the dielectric plate 210. In some embodiments, the edge ring 302 is placed on a quartz ring (not shown) disposed around the cooling plate 220. In some embodiments, the edge ring 302 is disposed around the dielectric plate 210 and the substrate 122. In some embodiments, the edge ring 302 is made of silicon (Si), silicon carbide (SiC), or graphite to reduce contamination on the substrate 122 during processing.

[0033] In operation, RF power applied to the cooling plate 220 establishes a sheath between the substrate 122 and the plasma 102. As a result, ions from the plasma 102 are attracted to the biased substrate 122, and the ions are accelerated through the sheath perpendicular to the equipotential lines within the sheath. When the edge ring 302 is disposed around the dielectric plate 210, the voltage potential on the edge ring is different from the voltage potential on the substrate 122. The difference in voltage potential causes the sheath to have a thicker shape above the edge ring 302 than above the substrate 122. As such, the equipotential lines within the sheath do not have a flat profile near the edge of the substrate 122, causing the ions to be accelerated at an angle around the edge ring 302 and resulting in a tilted etch profile problem around the edge ring 302.

[0034] In some embodiments, the third electrode 310 is embedded in the peripheral region of the dielectric plate 210 and is directly coupled to at least one of the first electrode 208 and the second electrode 218 via the plurality of conductive elements 308. In some embodiments, the plurality of conductive elements 308 are a plurality of second pillars. The third electrode 310 is vertically disposed between the first electrode 208 and the second electrode 218. In some embodiments, a third distance 312 between the third electrode 310 and the bottom surface of the notch in the upper peripheral edge of the dielectric plate 210 is about 0.8 mm to about 1.2 mm. In some embodiments, the third distance 312 is substantially equal to the first distance 228 and the second distance 230. The third electrode 310 advantageously creates a flatter sheath profile around the edge ring 302 to reduce or avoid etching profile tilt issues.

[0035] Figure 4 A cross-sectional top view of an electrostatic chuck at a location between the first electrode 208 and the second electrode 218 is depicted in accordance with at least some embodiments of the present disclosure. As discussed above, the first gas channel 222 is coupled to the gas inlet 224 disposed on the second side 204 of the dielectric plate 210. The first gas channel 222 includes a first end 418 coupled to the gas inlet 224. In some embodiments, the first gas channel 222 includes a network of gas channels extending horizontally across the dielectric plate 210 from the first end 418 to a plurality of second ends 426 to define a first gas chamber 404. The plurality of second ends 426 are coupled to corresponding gas outlets 226 of the plurality of gas outlets 226. In some embodiments, the network of gas channels is configured to be evenly spaced apart to provide substantially equal flow lengths and conductivities along each path of the first gas channel 222 from the first end 418 to each respective second end 426. Substantially equal conductivities mean within about ten percent.

[0036] In some embodiments, the second gas inlet 402 is disposed on the second side 204 of the dielectric plate 410 and is coupled to the second gas channel 330. A plurality of gas outlets are disposed on the first side 202 of the plate and are coupled to the second gas channel 330. The second gas channel 330 includes a first end 420 coupled to the second gas inlet 402. In some embodiments, the second gas channel 330 includes a network of gas channels extending horizontally across the dielectric plate 210 from the first end 420 to a plurality of second ends 414 to define a second plenum 406. The plurality of second ends 414 are coupled to corresponding gas outlets of the plurality of gas outlets on the first side 202 coupled to the second gas channel 330. In some embodiments, the network of gas channels is configured to be evenly spaced apart to provide substantially equal flow lengths and conductances along each path of the second gas channel 330 from the first end 420 to each respective second end 414. Substantially equal conductance means within about ten percent.

[0037] In some embodiments, the first gas chamber 404 is fluidly independent from the second gas chamber 406 within the dielectric plate 210 to advantageously provide greater uniformity or control over the temperature profile of the electrostatic chuck 200. In some embodiments, the plurality of gas outlets 226 coupled to the first gas channels 222 are disposed in a peripheral region of the dielectric plate 210 while the plurality of gas outlets coupled to the second gas channels 330 are disposed in a central region of the dielectric plate 210. In some embodiments, the plurality of gas outlets 226 coupled to the first gas channels 222 are disposed in a central region of the dielectric plate 210 while the plurality of gas outlets coupled to the second gas channels 330 are disposed in a peripheral region of the dielectric plate 210.

[0038] In some embodiments, the dielectric plate 210 is composed of two plates that are processed to form the first gas channel 222 and the second gas channel 330. In some embodiments, the two plates are sintered. In some embodiments, the two plates are diffusion bonded together after processing.

[0039] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.

Claims

1. An electrostatic chuck for use in a substrate processing chamber, include: a plate having a first side configured to support a substrate and a second side opposite the first side; a first electrode embedded in the plate proximate the first side; a second electrode embedded in the plate proximate the second side, wherein the second electrode extends radially outward from the first electrode; a plurality of conductive elements coupling the first electrode to the second electrode; a third electrode embedded in a peripheral region of the plate between the first electrode and the second electrode, wherein the third electrode extends vertically upward from the second electrode via a conductive element, and wherein the plate comprises a notch at an upper peripheral edge, and wherein a distance between the first electrode and the first side is substantially equal to a distance between the third electrode and a bottom surface of the notch; a first gas channel disposed within the plate and between the first electrode and the second electrode; a first gas inlet extending from the second side of the plate to the first gas channel; as well as a plurality of first gas outlets extending from the first side of the plate to the first gas channel, wherein the first gas channel comprises a plurality of gas channels fluidly connected within the plate and extending horizontally from the gas inlet across the electrostatic chuck between the first electrode and the second electrode to a plurality of ends corresponding to the plurality of first gas outlets, wherein at least some of the plurality of gas channels extend in a radial direction such that the first gas inlet is disposed radially inside or outside of the plurality of first gas outlets.

2. The electrostatic chuck of claim 1 , further comprising a second gas channel disposed within the plate and between the first electrode and the second electrode ； a second gas inlet disposed on the second side of the plate and coupled to the second gas channel; and a plurality of second gas outlets disposed on the first side of the plate and coupled to the second gas channel, wherein the second gas inlet is disposed radially inwardly or radially outwardly of the plurality of second gas outlets.

3. The electrostatic chuck of claim 1 , wherein the first gas inlet is disposed radially inward of the plurality of first gas outlets, and the electrostatic chuck further comprises: include: a second gas inlet extending to a second gas channel disposed within the plate and between the first electrode and the second electrode; and A plurality of second gas outlets extend from the second gas channel to the first side of the plate, wherein the plurality of second gas outlets are disposed radially inwardly of the second gas inlet and the plurality of first gas outlets.

4. The electrostatic chuck of claim 1, wherein the plurality of gas channels are configured to be evenly spaced apart to provide substantially equal flow lengths along respective paths of the first gas channels from the first gas inlet to respective ends thereof.

5. The electrostatic chuck of claim 1, wherein the second electrode extends radially outward from the first electrode.

6. The electrostatic chuck of claim 1, further comprising a third electrode embedded in a peripheral region of the plate and directly coupled to at least one of the first electrode and the second electrode.

7. The electrostatic chuck of claim 1, wherein a distance from the first electrode to the first side of the electrostatic chuck is substantially equal to a distance from the second electrode to the second side of the electrostatic chuck.

8. An electrostatic chuck for use in a substrate processing chamber, include: a plate having a first side and a second side opposite the first side; a first electrode embedded in the plate proximate the first side; a second electrode embedded in the plate proximate the second side, wherein the second electrode extends radially outward from the first electrode; a third electrode embedded in the peripheral region of the plate between the first electrode and the second electrode, wherein the third electrode extends vertically upward from the second electrode via a conductive element; as well as a plurality of first posts extending from the first electrode to the second electrode to point-couple the first electrode and the second electrode; wherein the plate comprises a notch at an upper peripheral edge, and wherein a distance between the first electrode and the first side is substantially equal to a distance between the third electrode and a bottom surface of the notch.

9. The electrostatic chuck of claim 8, wherein the plate is comprised of two plates bonded together.

10. The electrostatic chuck of claim 8, wherein a distance between the first electrode and the first side is 0.8 mm to 1.2 mm.

11. The electrostatic chuck of claim 8, wherein a distance between the second electrode and the second side is 0.8 mm to 1.2 mm.

12. The electrostatic chuck of claim 8, wherein the second electrode extends radially outward from the first electrode.

13. A process chamber, include: A chamber body having a substrate support disposed within an interior space of the chamber body, wherein the substrate support comprises an electrostatic chuck, the electrostatic chuck comprising: Cooling plate; a dielectric plate disposed above the cooling plate and having a first electrode, a second electrode, and a plurality of posts electrically coupling the first electrode to the second electrode; one or more first gas passages extending from a bottom surface of the electrostatic chuck into the dielectric plate; a plurality of second gas channels extending horizontally from the one or more first gas channels across the electrostatic chuck between the first electrode and the second electrode, wherein the plurality of second gas channels are in fluid communication within the dielectric plate; a plurality of third gas channels extending from the plurality of second gas channels to a top surface of the electrostatic chuck; and A third electrode is embedded in a peripheral region of the dielectric plate between the first electrode and the second electrode, wherein the third electrode extends vertically upward from the second electrode via a conductive element, and wherein the second electrode extends radially outward from the first electrode.

14. The process chamber of claim 13, wherein the electrostatic chuck includes a notch at an upper peripheral edge, and an edge ring is disposed in the notch.

15. The process chamber of claim 14, wherein the electrostatic chuck comprises a third electrode disposed in a peripheral region of the electrostatic chuck, between the first electrode and the second electrode, and directly coupled to the second electrode.

16. The process chamber of claim 13, wherein a distance from the first electrode to a top surface of the electrostatic chuck is substantially equal to a distance from the second electrode to a bottom surface of the electrostatic chuck.

17. The process chamber of claim 13, wherein the cooling plate is made of aluminum.

18. The process chamber of claim 13, further comprising a porous plug disposed in the one or more first gas channels at an interface between the dielectric plate and the cooling plate.

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