Apparatus for improved high pressure plasma processing

Abstract

This document provides embodiments of an apparatus for high-voltage plasma processing. In some embodiments, the apparatus includes an isolation plate and a grounding bracket for supporting a substrate (such as an electrostatic chuck) within a plasma processing chamber. In some embodiments, an apparatus for high-voltage plasma processing includes: an electrostatic chuck; a grounding return bracket spaced apart from the electrostatic chuck; and a dielectric plate disposed between the electrostatic chuck and the grounding return bracket.

Description

Technical Field

[0001] The embodiments disclosed herein generally relate to substrate processing equipment. Prior Technology

[0002] Plasma processing chambers typically include a substrate support for supporting a substrate and a target disposed opposite the substrate support. The target provides a source of material for sputtering onto the substrate during processing. RF power is supplied to the plasma processing chamber to generate plasma in a processing space disposed between the target and the substrate support. Some plasma processes require high voltage to achieve the desired film deposition properties and locations on the substrate (e.g., to obtain good underbody coverage for features disposed on the substrate). However, the inventors have observed arcing and plasma leakage during such high-voltage plasma processes.

[0003] Therefore, the inventors have provided an improved device for high-voltage plasma processing. Summary of the Invention

[0004] This document provides embodiments of an apparatus for high-voltage plasma processing. In some embodiments, the apparatus includes an isolation plate and a grounding bracket for substrate support (such as an electrostatic chuck) within a plasma processing chamber. In some embodiments, the plasma processing chamber may be a physical vapor deposition chamber. In some embodiments, the disclosed isolation plate and grounding bracket configuration enables plasma power up to about 6 kW at pressures up to about 480 mTorr, while providing plasma using RF power in the extremely high frequency (VHF) band. Compared to conventional substrate support designs, embodiments of the disclosed apparatus enable stable plasma formation with reduced or no arcing and / or plasma leakage.

[0005] In some embodiments, an apparatus for high-voltage plasma processing includes: an electrostatic chuck; a grounded return support spaced apart from the electrostatic chuck; and a dielectric plate disposed between the electrostatic chuck and the grounded return support.

[0006] In some embodiments, a processing chamber for high-voltage plasma processing includes: a chamber body having an internal space therein; and a substrate support disposed in the internal space. The substrate support may include: an electrostatic chuck; a grounding return bracket spaced apart from the electrostatic chuck; and a dielectric plate disposed between the electrostatic chuck and the grounding return bracket. In some embodiments, the processing chamber further includes a target disposed in the internal space opposite the substrate support. In some embodiments, the processing chamber further includes a VHF RF source coupled to the processing chamber to provide RF power in the VHF band to the processing chamber.

[0007] Other and further embodiments of this disclosure are described below. Simple Explanation of the Diagram

[0008] The embodiments of this disclosure have been briefly summarized above and are discussed in more detail below, which can be understood by referring to the exemplary embodiments of this disclosure illustrated in the accompanying drawings. However, the accompanying drawings only illustrate typical embodiments of this disclosure, and since this disclosure allows for other equivalent embodiments, the accompanying drawings should not be considered as a limitation on the scope of this disclosure.

[0009] Figure 1 illustrates a schematic side view of a processing chamber configured for improved high-voltage plasma processing according to at least some embodiments of the present disclosure.

[0010] Figure 2 illustrates a schematic side view of a processing chamber configured for improved high-voltage plasma processing according to at least some embodiments of the present disclosure.

[0011] For ease of understanding, the same numerical designations are used to represent the same elements in the figures where possible. For clarity, the figures are not drawn to scale and may be simplified. Elements and features of one embodiment may be advantageously combined with those of other embodiments without further description. Implementation

[0012] This document provides embodiments of an apparatus for high-voltage plasma processing. In some embodiments, the apparatus includes an isolation plate and a grounding bracket for substrate support (such as an electrostatic chuck) within a plasma processing chamber. In some embodiments, the plasma processing chamber may be a physical vapor deposition chamber. In some embodiments, the disclosed isolation plate and grounding bracket configuration enables plasma power up to about 6 or up to about 9 kW at pressures up to about 480 mTorr, while providing plasma using RF power in the VHF band (e.g., between about 30 and about 300 MHz, or in some embodiments, about 100-200 MHz). Compared to conventional substrate support designs, embodiments of the disclosed apparatus enable stable plasma formation with reduced or no arcing and / or plasma leakage. In the embodiments, the design of the isolation plate and grounding bracket advantageously increases the capacitance between the RF paths by increasing the distance between the RF thermal signal and the electrostatic chuck and the RF backhaul, thereby reducing and / or eliminating stray plasma while operating at higher chamber pressures and VHF power. An example of a suitable application for the disclosed device is for depositing tungsten in features, which requires high-voltage plasma for good undercover and minimal channel overhang. The inventors have observed arcing and unstable plasma when performing such processes at the required pressure using conventional RF grounded backhaul supports.

[0013] Figure 1 illustrates a schematic side view of a processing chamber 100 (such as a plasma processing chamber) configured for high-voltage plasma processing according to at least some embodiments of the present disclosure. In some embodiments, the processing chamber 100 is a physical vapor deposition chamber. However, other types of processing chambers configured for different processes may also be used with or modified for the embodiments described herein.

[0014] Processing chamber 100 is a vacuum chamber adapted to maintain sub-atmospheric pressure within internal space 120 during substrate processing. Processing chamber 100 includes a chamber body 106 covered by a cover assembly 104, which surrounds a processing space 119 located in the upper half of internal space 120. Chamber body 106 and cover assembly 104 may be made of metal, such as aluminum. Chamber body 106 may be grounded via coupling to ground 115.

[0015] A substrate support 124 is disposed within an internal space 120 to support and hold a substrate 122 (such as a semiconductor wafer) or other electrostatically holdable substrate. The substrate support 124 typically includes an electrostatic chuck 150 disposed on a base 136 and a hollow support shaft 112 for supporting the base 136 and the electrostatic chuck 150. The electrostatic chuck 150 includes a dielectric plate having one or more electrodes 154 disposed therein. The base 136 is generally made of a metal (such as stainless steel). The base 136 may include a ground return bracket 129 for providing an RF return path for RF supplied to the processing chamber. The ground return bracket 129 is advantageously positioned away from the back of the electrostatic chuck 150 and away from the one or more electrodes 154, which advantageously minimizes arcing. A dielectric plate 128 is disposed between the ground return bracket 129 and the electrostatic chuck 150 to prevent plasma from illuminating in this area. The dielectric plate 128 isolates the self-processing recess of the grounding return bracket 129 and the electrostatic chuck 150.

[0016] In some embodiments, dielectric plate 128 may be directly coupled to one or both of ground return bracket 129 and electrostatic chuck 150, or disposed against one or both of ground return bracket 129 and electrostatic chuck 150. Dielectric plate 128 may be a single component or may be made of multiple components that provide a dielectric gap between ground return bracket 129 and electrostatic chuck 150, as disclosed herein. In some embodiments, the outer diameter of dielectric plate 128 is larger than the outer diameter of electrostatic chuck 150.

[0017] For example, in some embodiments, the distance between one or more electrodes 154 and the ground return bracket 129 is selected to prevent RF coupling, and the distance between the one or more electrodes 154 and the ground return bracket 129 will depend on the conditions in the chamber (such as RF power, chamber pressure, or similar conditions). For a given chamber pressure, bias power, etc., RF coupling will occur at certain threshold distances. In some embodiments, the threshold distance is on the order of several millimeters. In some embodiments, the dielectric plate 128 can be on the order of larger quantities (such as at least 10 mm, at least 20 mm, or at least 30 mm, or about 30 mm in some embodiments) to separate the electrostatic chuck 150 from the ground return bracket 129. The greater thickness of the dielectric plate 128 (and thus the separation between the electrostatic chuck 150 and the ground return bracket 129) is beneficial for enhanced arc and / or stray plasma protection, even when operating at pressure / power ranges much higher than typical PVD processes (e.g., at about 350 mTorr or about 480 mTorr, or higher, up to 6 or up to about 9 kW RF power, and at RF frequencies between about 30 and about 300 MHz, or in some embodiments, about 100-200 MHz).

[0018] Hollow support shaft 112 provides conduits for supplying the electrostatic chuck 150 with back gas, processing gas, fluid, coolant, electricity, etc. In some embodiments, hollow support shaft 112 is coupled to lifting mechanism 113 (such as an actuator or motor) that provides vertical movement of the electrostatic chuck 150 between an upper processing position (as shown in FIG. 1) and a lower transfer position (not shown). Bellows assembly 110 is disposed around hollow support shaft 112 and coupled between the electrostatic chuck 150 and the bottom surface 126 of processing chamber 100 to provide a resilient seal that allows vertical movement of the electrostatic chuck 150 while preventing vacuum loss within processing chamber 100. Bellows assembly 110 also includes a lower bellows flange 164 or other suitable sealing element that contacts O-ring 165, which contacts bottom surface 126 to help prevent chamber vacuum loss.

[0019] The hollow support shaft 112 provides a conduit for coupling the suction cup power supply 140 and RF sources (such as RF power supply 174 and RF bias power supply 117) to the electrostatic chuck 150. In some embodiments, the RF power supply 174 and RF bias power supply 117 are coupled to the electrostatic chuck 150 via individual RF matching networks (RF matching network 116 is illustrated only). In some embodiments, the substrate support 124 may alternatively include AC or DC bias power.

[0020] The substrate lift 130 may include a lifting pin 109 mounted on a platform 108 connected to a shaft 111 coupled to a second lifting mechanism 132 for raising and lowering the substrate lift 130, such that a substrate 122 may be placed on or removed from an electrostatic chuck 150. The platform 108 may be in the form of a ring lift. The electrostatic chuck 150 may include through-holes to receive the lifting pin 109. A bellows assembly 131 is coupled between the substrate lift 130 and the bottom surface 126 to provide a resilient seal that maintains a chamber vacuum during vertical movement of the substrate lift 130.

[0021] During processing, a target 138 (as a cathode) is disposed in a processing space 119, opposite a substrate support 124, to at least partially define the processing space therebetween. The target 138 includes a cathode surface defined by a surface of the target 138 facing the processing space. The substrate support 124 has a support surface having a plane substantially parallel to the sputtering surface of the target 138. The target 138 is connected to one or both of a DC power supply 190 and / or an RF power supply 174. The DC power supply 190 can apply a bias voltage to the target 138 relative to a processing shield 105 disposed in the chamber and surrounding the processing space 119.

[0022] The target 138 typically includes a sputtering plate 142 mounted on a backplate 144, although a monolithic target (such as a sputtering plate without a backplate) can also be used. The sputtering plate 142 contains the material to be sputtered onto the substrate 122. The backplate 144 is made of a metal, such as stainless steel, aluminum, copper-chromium, or copper-zinc. The backplate 144 may be made of a material with sufficiently high thermal conductivity to dissipate the heat generated in the target 138, which is generated by eddy currents in the sputtering plate 142 and the backplate 144, as well as by high-energy ions from plasma impacting the sputtering plate 142.

[0023] In some embodiments, the processing chamber 100 includes a magnetic field generator 156 to shape a magnetic field around the target 138 to improve sputtering of the target 138. The magnetic field generator 156 can enhance plasma generated by a capacitor. In the magnetic field generator 156, for example, a plurality of magnets 151 (such as permanent magnets or electromagnetic coils) can provide a magnetic field in the processing chamber 100. The processing chamber 100 has a rotating magnetic field having an axis of rotation perpendicular to the plane of the substrate 122. The processing chamber 100 may additionally or alternatively include the magnetic field generator 156, which generates a magnetic field near the target 138 to increase the ion density in the processing space 119 to improve target sputtering. A plurality of magnets 151 may be disposed in a recess 153 of the cap assembly 104. A coolant (such as water) may be disposed in or circulated through the recess 153 to cool the target 138.

[0024] Processing chamber 100 includes a processing sleeve 102 that circumscribing various chamber components to prevent unwanted reactions between these components and the ionized processing material. Processing sleeve 102 includes a processing shield 105 surrounding a substrate support 124 and a target 138 to at least partially define a processing space 119. For example, processing shield 105 may define an outer boundary of processing space 119. Processing shield 105 includes an anode surface defined by a surface of processing shield 105 facing the processing space. In some embodiments, processing shield 105 is made of a metal such as aluminum. Processing shield 105 may include an outer flange that rests on chamber body 106 to support the processing shield in place. An isolation ring 114 may be disposed on top of the outer flange of processing shield 105 between processing shield 105 and target 138 to avoid providing a grounding path between target 138 and processing shield 105.

[0025] In some embodiments, the processing assembly 102 includes a deposition ring 170 resting on the outer edge of the electrostatic chuck 150. In some embodiments, the processing assembly 102 includes a cover ring 180 disposed on the processing shield 105 to form a tortuous gas flow path therebetween. In some embodiments, at the processing position, the radially inner portion of the cover ring 180 rests on the deposition ring 170 to reduce or prevent plasma leakage therebetween.

[0026] In some embodiments, when the substrate support 124 is in the processing position, the distance 158 between the target 138 and the substrate support 124 is about 60.0 mm to about 160.0 mm, but other spacings may also be used.

[0027] In some embodiments, a plurality of grounding loops 172 are disposed between the processing shield 105 and the base 136. For example, the grounding loops 172 may be coupled to the grounding return bracket 129. The grounding loops 172 typically include a loop of conductive material (or alternatively, a conductive strip, spring member, or the like) configured to electrically couple the processing shield 105 to the base 136, for example, to the grounding return bracket 129, when the substrate support 124 is in the processing position. In some embodiments, the plurality of grounding loops 172 are coupled to the outer lip of the base 136, for example, along the outer edge of the grounding return bracket 129, such that in the processing position, the grounding loops 172 contact the processing shield 105 to electrically couple the processing shield 105 and the base 136 or the grounding return bracket 129. In some embodiments, in the transfer position, the grounding loops 172 are separated from the processing shield 105.

[0028] Processing chamber 100 is coupled to and in fluid communication with vacuum system 184, which includes a gate valve or throttle valve (not shown) and a vacuum pump (not shown) for venting processing chamber 100. The pressure inside processing chamber 100 can be regulated by adjusting the throttle valve and / or the vacuum pump. Processing chamber 100 is also coupled to and in fluid communication with gas supply 118, which supplies one or more processing gases to processing chamber 100 for processing substrate 122 disposed therein. Slit valve 148 is coupled to chamber body 106 and aligned with an opening in the sidewall of chamber body 106 to facilitate the transfer of substrate 122 in and out of chamber body 106.

[0029] In use, DC power supply 190 powers target 138 and other chamber components connected to DC power supply 190, and in conjunction with RF power supply 174, provides energy (e.g., from process gas supply 118) to sputter gas to form a plasma. The formed plasma impacts and impinges on the sputtering surface of target 138 to sputter material off target 138 and onto substrate 122. In some embodiments, the RF energy provided by RF power supply 174 can be in the frequency range of the VHF band (e.g., about 30 to about 300 MHz). In some embodiments, multiple RF power supplies (i.e., two or more) can be provided to provide RF energy at multiple frequencies (including frequencies outside the VHF band). Additional RF power supplies (such as RF bias power supply 117) can also be used to provide a bias voltage to substrate support 124 to attract ions to form plasma onto substrate 122.

[0030] Figure 2 illustrates a schematic side view of a processing chamber 200 (such as a plasma processing chamber) configured for high-voltage plasma processing according to at least some embodiments of the present disclosure. The processing chamber 200 is similar to the processing chamber 100 described in Figure 1, except as described below.

[0031] The processing chamber 200 also includes a substrate support 124 disposed within the internal space 120 to support and hold a substrate 122 (such as a semiconductor wafer) or other electrostatically holdable substrate. The substrate support 124 may also include an electrostatic chuck 150 disposed on a base 136 and a hollow support shaft 112 for supporting the base 136 and the electrostatic chuck 150. The electrostatic chuck 150 includes a dielectric plate having one or more electrodes disposed therein. The base 136 may include a ground return bracket 129 or may be coupled to the ground return bracket 129 for providing an RF return path for RF supplied to the processing chamber. The ground return bracket 129 is advantageously positioned away from the back of the electrostatic chuck 150, which advantageously minimizes arcing.

[0032] In some embodiments, the grounding return bracket 129 is typically bowl-shaped, having a recessed central portion 202 and a radially extending outer flange 204. In some embodiments, the radially extending outer flange is substantially flat, such as horizontal. The recessed central portion may further include a central opening 206 through which the hollow support shaft 112 and the bellows assembly 110 may extend.

[0033] The housing 208 of the base 136 at least partially surrounds the internal space 210 disposed below the electrostatic chuck 150 for mounting or arranging other components of the substrate support 124. The housing includes a base 212 and sidewalls 214, the base 212 having a central opening coupled to the hollow support shaft 112, and the sidewalls 214 extending from the base 212 to the back of the electrostatic chuck 150. A grounding return bracket 129 may interface with or be coupled to the housing 208, for example, around the periphery of the base 212. A bellows assembly 110 may be coupled to the bottom of the base 212 around the hollow support shaft 112.

[0034] Grounding loop 172 may be disposed on or coupled to grounding return bracket 129, for example, on radially extending outer flange 204. For example, grounding loop 172 may be bolted or otherwise secured along the outer periphery of radially extending outer flange 204 by plate 216 and bolts 218. For example, in some embodiments, the outer diameter of dielectric plate 128 is larger than the outer diameter of electrostatic chuck 150, grounding return bracket 129 (such as radially extending outer flange 204) extends radially beyond the outer diameter of dielectric plate 128, and grounding loop 192 is disposed on or coupled to grounding return bracket 129 (such as radially extending outer flange 204) radially outward from dielectric plate 128.

[0035] A dielectric plate 128 is disposed between the grounding return bracket 129 and the electrostatic chuck 150 to prevent plasma from emitting light in this area. The dielectric plate 128 isolates the grounding return bracket 129 from the processing recess and the electrostatic chuck 150. In some embodiments, the dielectric plate 128 is annular or includes a central opening sized to fit around a housing 208 (such as a sidewall 214 of housing 208) surrounding the base 136. A plurality of through holes 220 may be provided through the dielectric plate in the same direction as the central opening (e.g., vertically) to receive fasteners 222 (e.g., bolts) to secure the dielectric plate 128 to the grounding return bracket 129 through corresponding openings in the grounding return bracket 129.

[0036] Aligned openings 224, 226, and 228 can be formed through the dielectric plate 128, the ground return bracket 129, and the electrostatic chuck 150, respectively, to facilitate the movement of the lifting pins therethrough to raise or lower the substrate relative to the support surface of the electrostatic chuck 150 (as described above).

[0037] Although the foregoing description is directed to embodiments of this disclosure, other and further embodiments disclosed herein may be designed without departing from the basic scope of this disclosure.

[0038] 100: Processing Chamber 102: Processing Set 104: Cover assembly 105: Handling shielding components 106: Main body of the chamber 108: Platform 109: Lifting and Selling 110: Bellows assembly 111: Axis 112: Hollow support shaft 113: Lifting Mechanism 114: Isolation Ring 115: Land 116: RF Matching Network 117: RF bias power supply 118: Handling Gas Supply 119: Processing Space 120: Interior Space 122:Substrate 124: Substrate support 126: Bottom surface 128: Dielectric board 129: Grounding return support 130: Substrate Lifting Machine 132: Second lifting mechanism 136: Base 138: Target 140: Suction Cup Power Supply 142: Sputtering plate 144: Backplate 148: Slit Valve 150: Electrostatic chuck 151: Multiple magnets 153: concave part 154: Electrode 156: Magnetic field generator 158: Distance 164: Lower bellows flange 165: O-ring 170: Sedimentary ring 172: Grounding circuit 174: RF Power Supply 180: Cover ring 184: Vacuum System 190: DC power supply 200: Processing Chamber 202: The central part of the depression 204: Radially extending outer flange 206: Center Opening 208: Casing 210: Interior Space 212: Base 214: Sidewall 216: Board 218: Bolt 220: Through hole 222: Fasteners 224: Aligned opening 226: Aligned opening 228: Aligned opening

[0039] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. An apparatus for high-voltage plasma treatment, comprising: An electrostatic chuck; A housing that at least partially surrounds an internal space located directly below the electrostatic chuck; A grounding return bracket spaced apart from the electrostatic chuck; and a dielectric plate disposed between the electrostatic chuck and the grounding return bracket, wherein the dielectric plate includes a central opening through which the housing extends.

2. The device as claimed in claim 1, wherein the dielectric plate separates the electrostatic chuck from the grounded return bracket by at least 10 mm.

3. The device as claimed in claim 1, wherein the housing further comprises: One base; and sidewalls, which extend from the base to a back of the electrostatic chuck.

4. The device as described in claim 3, further comprising: A hollow support shaft, wherein the base includes a central opening coupled to the hollow support shaft such that an interior of the hollow support shaft is coupled to the interior space.

5. The device as claimed in claim 1, wherein the grounding return bracket is coupled to the housing.

6. The device as described in any one of claims 1 to 5, wherein the grounding return bracket is typically bowl-shaped, having a recessed central portion and a radially extending outer flange.

7. The device as claimed in claim 6, wherein the radially extending outer flange is substantially flat, and wherein the central portion of the recess includes a central opening through which a hollow support shaft supporting the electrostatic chuck can extend.

8. The device as described in any one of claims 1 to 5 further includes a plurality of grounding loops coupled to the grounding return bracket.

9. The device as claimed in claim 8, wherein an outer diameter of the dielectric plate is larger than an outer diameter of the electrostatic chuck, the grounding return bracket extends radially beyond the outer diameter of the dielectric plate, and the plurality of grounding loops are coupled to the grounding return bracket radially outside the dielectric plate.

10. The device as claimed in any one of claims 1 to 5 further includes a plurality of through holes passing through the dielectric plate to receive a fastener to secure the dielectric plate to the grounding return bracket through a plurality of corresponding openings in the grounding return bracket.

11. The device as claimed in any one of claims 1 to 5, further comprising aligned openings through the dielectric plate, the ground return bracket and the electrostatic chuck, for facilitating movement of a lifting pin therethrough to raise or lower a substrate relative to a support surface of the electrostatic chuck.

12. The device as claimed in either claim 1 or 2, wherein the housing further includes a base and sidewalls, the base having a central opening, the sidewalls extending from the base to a back of the electrostatic chuck, and the device further includes: a hollow support shaft coupled to the base around the central opening such that an interior of the hollow support shaft is coupled to the interior space, wherein the grounding return bracket is coupled to the housing and is generally bowl-shaped, having a recessed central portion and a radially extending outer flange, the recessed central portion having a central opening through which the hollow support shaft extends; and a plurality of grounding loops coupled to the radially extending outer flange of the grounding return bracket.

13. An apparatus for high-voltage plasma processing, comprising: An electrostatic chuck; A grounded return bracket, which is spaced apart from the electrostatic chuck; A dielectric plate having a central opening disposed between the electrostatic chuck and the grounding return bracket, wherein the dielectric plate separates the electrostatic chuck from the grounding return bracket by at least 10 mm; a housing at least partially surrounding an internal space disposed directly below the electrostatic chuck, the housing including a base and sidewalls, the base having a central opening, the sidewalls extending from the base to a back of the electrostatic chuck within the central opening of the dielectric plate; a hollow support shaft coupled to the base around the central opening such that an interior of the hollow support shaft is coupled to the internal space, wherein the grounding return bracket is coupled to the housing and is generally bowl-shaped, having a recessed central portion and a radially extending outer flange, the recessed central portion having a central opening through which the hollow support shaft extends; Aligned openings, which are disposed through the dielectric plate, the grounding return bracket and the electrostatic chuck to facilitate the movement of a lifting pin therethrough to raise or lower a substrate relative to a support surface of the electrostatic chuck; and a plurality of grounding loops coupled to the radially extending outer flange of the grounding return bracket.

14. A processing chamber for high-voltage plasma processing, comprising: A chamber body having an internal space therein; And a substrate support comprising the device as described in any one of claims 1 to 5, the substrate support being disposed in the internal space.

15. The processing chamber as described in claim 14, further comprising: A target is disposed in the internal space opposite to the substrate support.

16. The processing chamber as described in claim 14, further comprising: A VHF RF source is coupled to the processing chamber to provide RF power in the VHF band to the processing chamber.

17. The processing chamber as described in any one of claims 14 to 16 further includes a plurality of grounding loops coupled to the grounding return bracket.

18. The processing chamber as claimed in claim 17, wherein an outer diameter of the dielectric plate is larger than an outer diameter of the electrostatic chuck, the grounding return bracket extends radially beyond the outer diameter of the dielectric plate, and the plurality of grounding loops are coupled to the grounding return bracket radially outside the dielectric plate.

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