Apparatus for improved high pressure plasma processing

Abstract

Embodiments of an apparatus for high pressure plasma processing are provided herein. In some embodiments, the apparatus includes an insulator plate and a grounded bracket for a substrate support (such as an electrostatic chuck) in a plasma processing chamber. In some embodiments, the apparatus for high pressure plasma processing includes an electrostatic chuck, a grounded return bracket spaced apart from the electrostatic chuck, and a dielectric plate disposed between the electrostatic chuck and the grounded return bracket.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] Embodiments of the present disclosure generally relate to substrate processing equipment. [Background technology]

[0002]

[0002] A plasma processing chamber typically includes a substrate support for supporting a substrate and a target positioned 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 a plasma in a processing space positioned between the target and the substrate support. Some plasma processes have required high pressures to enable desired film deposition characteristics and location on the substrate (e.g., for good bottom surface coverage within features located on the substrate). However, the present inventors have observed that arcing and plasma leakage can occur during such higher pressure plasma processes.

[0003]

[0003] Accordingly, the present inventors have provided an improved apparatus for high pressure plasma processing. Summary of the Invention

[0004]

[0004] Embodiments of an apparatus for high-pressure plasma processing are provided herein. In some embodiments, the apparatus includes an insulator plate and grounding bracket for a substrate support (such as an electrostatic chuck) in a plasma processing chamber. In some embodiments, the plasma processing chamber can be a physical vapor deposition chamber. In some embodiments, the disclosed insulator plate and grounding bracket configuration enables plasma power of up to about 6 kW at pressures of up to about 480 mTorr while providing the plasma using RF power in the very high frequency (VHF) band. Embodiments of the disclosed apparatus enable stable plasma generation with reduced or no arcing and / or plasma leakage compared to conventional substrate support designs.

[0005]

[0005] In some embodiments, an apparatus for high-pressure plasma processing includes an electrostatic chuck, a grounded return bracket spaced apart from the electrostatic chuck, and a dielectric plate positioned between the electrostatic chuck and the grounded return bracket.

[0006] In some embodiments, a process chamber for high-pressure plasma processing includes a chamber body having an interior space therein and a substrate support disposed within the interior space. The substrate support may include an electrostatic chuck, a ground return bracket spaced apart from the electrostatic chuck, and a dielectric plate disposed between the electrostatic chuck and the ground return bracket. In some embodiments, the process chamber further includes a target disposed within the interior space opposite the substrate support. In some embodiments, the process chamber further includes a VHF RF source coupled to the process chamber for providing RF power within the VHF band to the process chamber.

[0007]

[0007] Other and further embodiments of the present disclosure are described below.

[0008]

[0008] Embodiments of the present disclosure, briefly summarized above and described in more detail below, can be understood by reference to exemplary embodiments thereof as illustrated in the accompanying drawings. However, because the present disclosure may admit of other equally effective embodiments, the accompanying drawings depict only typical embodiments of the present disclosure and therefore should not be considered limiting in scope. [Brief explanation of the drawings]

[0009] [Figure 1]

[0009] A schematic side view of a process chamber configured for improved high pressure plasma processing according to at least some embodiments of the present disclosure is shown. [Figure 2]

[0010] 1 shows a schematic side view of a process chamber configured for improved high-pressure plasma processing in accordance with at least some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0011] To facilitate understanding, the same reference numerals have been used, where possible, to designate identical elements common to the figures. The figures are not to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further description.

[0011]

[0012] Embodiments of an apparatus for high-pressure plasma processing are provided herein. In some embodiments, the apparatus includes an insulator plate and grounding bracket for a substrate support (such as an electrostatic chuck) within a plasma processing chamber. In some embodiments, the plasma processing chamber can be a physical vapor deposition chamber. In some embodiments, the disclosed insulator plate and grounding bracket configuration enables plasma power of up to about 6 kW or up to about 9 kW at pressures of up to about 480 mTorr while providing plasma using RF power within the very high frequency (VHF) band (e.g., about 30 to about 300 MHz, or in some embodiments, about 100-200 MHz). Embodiments of the disclosed apparatus enable stable plasma generation with reduced or no arcing and / or plasma leakage compared to conventional substrate support designs. In some embodiments, the insulator plate and grounding bracket design advantageously increases the distance between the RF hot signal and RF return to the electrostatic chuck, thereby increasing the capacitance between the RF paths and reducing and / or eliminating stray plasma while operating at higher chamber pressures and VHF power. One example of a suitable application for the disclosed apparatus is tungsten deposition in features, which requires high pressure plasma to minimize channel overhang and provide good underside coverage. The inventors have observed arcing and unstable plasmas when performing such processes at the required pressures using conventional RF ground return brackets.

[0012]

[0013] 1 shows a schematic side view of a process chamber 100 (e.g., a plasma processing chamber) configured for high-pressure plasma processing, in accordance with at least some embodiments of the present disclosure. In some embodiments, the process chamber 100 is a physical vapor deposition chamber. However, other types of processing chambers configured for different processes may also be used or adapted for use in the embodiments described herein.

[0013]

[0014] The process chamber 100 is a reduced pressure chamber suitably adapted to maintain a sub-atmospheric pressure within an interior space 120 during substrate processing. The process chamber 100 includes a chamber body 106 covered by a lid assembly 104 that encloses a processing space 119 located within the upper half of the interior space 120. The chamber body 106 and the lid assembly 104 may be made of a metal such as aluminum. The chamber body 106 may be grounded via a connection to a ground terminal 115.

[0014]

[0015] A substrate support 124 is disposed within the interior space 120 for supporting and holding a substrate 122, such as a semiconductor wafer (or other such substrate that may be electrostatically held). The substrate support 124 may generally include an electrostatic chuck 150 disposed on a pedestal 136 and a hollow support shaft 112 for supporting the pedestal 136 and the electrostatic chuck 150. The electrostatic chuck 150 includes a dielectric plate having one or more electrodes 154 disposed therein. The pedestal 136 is generally made of a metal such as stainless steel. The pedestal 136 may include a ground return bracket 129 to provide an RF return path for RF supplied to the process chamber. The ground return bracket 129 is advantageously positioned away from the backside of the electrostatic chuck 150 and away from the one or more electrodes 154. This advantageously minimizes arcing. The dielectric plate 128 is disposed between the ground return bracket 129 and the electrostatic chuck 150 to prevent ignition of a plasma in this region. The dielectric plate 128 insulates the ground return bracket 129 from the process cavity and the electrostatic chuck 150.

[0015]

[0016] In some embodiments, the dielectric plate 128 may be directly coupled to or disposed in contact with either or both of the ground return bracket 129 and the electrostatic chuck 150. The dielectric plate 128 may be a single component or may be fabricated from multiple components that provide a dielectric gap between the ground return bracket 129 and the electrostatic chuck 150 as disclosed herein. In some embodiments, the dielectric plate 128 has an outer diameter that is larger than the outer diameter of the electrostatic chuck 150.

[0016]

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

[0017]

[0018] The hollow support shaft 112 provides a conduit for providing, for example, backside gas, process gas, fluid, coolant, power, etc., to the electrostatic chuck 150. In some embodiments, the hollow support shaft 112 is coupled to a lift 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). A bellows assembly 110 is disposed about the hollow support shaft 112 and coupled between the electrostatic chuck 150 and the lower surface 126 of the process chamber 100 to provide a flexible seal that allows vertical movement of the electrostatic chuck 150 while preventing loss of reduced pressure from within the process chamber 100. The bellows assembly 110 also includes a lower bellows flange 164 that contacts an O-ring 165 or other suitable sealing element that contacts the lower surface 126 to help prevent loss of reduced chamber pressure.

[0018]

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

[0019]

[0020] The substrate lift 130 may include lift pins 109 mounted on a platform 108 connected to a shaft 111. The shaft 111 is coupled to a second lift mechanism 132 for raising and lowering the substrate lift 130. The substrate 122 may thereby be placed on or removed from the electrostatic chuck 150. The platform 108 may take the form of a hoop lift. The electrostatic chuck 150 may include through holes for receiving the lift pins 109. A bellows assembly 131 is coupled between the substrate lift 130 and the lower surface 126 to provide a flexible seal. The flexible seal maintains the vacuum in the chamber during vertical movement of the substrate lift 130.

[0020]

[0021] A target 138, which acts as a cathode during processing, is disposed within the processing space 119 opposite the substrate support 124 to at least partially define a process space therebetween. The target 138 includes a cathode surface facing a surface of the target 138, the cathode surface being defined by the processing space. The substrate support 124 has a support surface with a plane substantially parallel to a 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 process shield 105 disposed within the chamber and surrounding the processing space 119.

[0021]

[0022] The target 138 typically includes a sputtering plate 142 attached to a backing plate 144, although monolithic targets can also be used (e.g., a sputtering plate without a backing plate). The sputtering plate 142 contains the material to be sputtered onto the substrate 122. The backing plate 144 is made of a metal, such as stainless steel, aluminum, copper-chromium, or copper-zinc. The backing plate 144 can be made of a material with a sufficiently high thermal conductivity to dissipate heat generated within the target 138. Heat is generated from eddy currents that occur within the sputtering plate 142 and backing plate 144, and also from the impact of energetic ions from the generated plasma onto the sputtering plate 142.

[0022]

[0023] In some embodiments, the process chamber 100 includes a magnetic field generator 156 for creating a magnetic field around the target 138 to improve sputtering of the target 138. The capacitively generated plasma may be enhanced by the magnetic field generator 156. In the magnetic field generator 156, for example, a plurality of magnets 151 (e.g., permanent magnets or electromagnetic coils) may provide a magnetic field within the process chamber 100. The magnetic field has a rotating magnetic field with an axis of rotation perpendicular to the plane of the substrate 122. The process chamber 100 may also or alternatively include the magnetic field generator 156. That is, the magnetic field generator 156 generates a magnetic field near the target 138 to increase ion density within the processing space 119 to improve sputtering of the target material. The plurality of magnets 151 may be disposed within a cavity 153 within the lid assembly 104. A coolant, such as water, may be disposed within or circulated through the cavity 153 to cool the target 138.

[0023]

[0024] The process chamber 100 includes a process kit 102 that circumscribes various components to prevent undesired reactions between such components and the ionized process material. The process kit 102 includes a process shield 105 that surrounds the substrate support 124 and the target 138 to at least partially define a processing space 119. For example, the process shield 105 may define the outer boundary of the processing space 119. The process shield 105 includes an anode surface defined by the processing space that faces a surface of the process shield 105. In some embodiments, the process shield 105 is made of a metal such as aluminum. The process shield 105 may include an outer flange mounted on the chamber body 106 to support the process shield in place. An insulator ring 114 may be positioned on the outer flange of the process shield 105 between the process shield 105 and the target 138 to prevent a ground path between the process shield 105 and the target 138.

[0024]

[0025] In some embodiments, the process kit 102 includes a deposition ring 170 mounted on the outer edge of the electrostatic chuck 150. In some embodiments, the process kit 102 includes a cover ring 180 disposed on the process shield 105 to form a serpentine gas flow path therebetween. In some embodiments, in the processing position, a radially inner portion of the cover ring 180 mounts on the deposition ring 170 to reduce or prevent plasma leakage therebetween.

[0025]

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

[0026]

[0027] In some embodiments, multiple ground loops 172 are disposed between the process shield 105 and the pedestal 136. For example, the ground loops 172 may be coupled to the ground return bracket 129. The ground loops 172 may generally comprise loops of conductive material, or alternatively, may comprise conductive straps, spring members, or the like. They are configured to electrically couple the process shield 105 to the pedestal 136 (e.g., to the ground return bracket 129) when the substrate support 124 is in the processing position. In some embodiments, the multiple ground loops 172 are coupled to the outer lip of the pedestal 136, such as along the outer edge of the ground return bracket 129. Thus, in the processing position, the ground loops 172 contact the process shield 105 and electrically couple the process shield 105 to the pedestal 136 (or the ground return bracket 129). In some embodiments, in the transfer position, the ground loops 172 are spaced apart from the process shield 105.

[0027]

[0028] The process chamber 100 is coupled to and in fluid communication with a pressure reduction system 184. The pressure reduction system 184 includes a gate or throttle valve (not shown) and a vacuum pump (not shown) used to evacuate the process chamber 100. The pressure inside the process chamber 100 may be adjusted by adjusting the throttle valve and / or the vacuum pump. The process chamber 100 is also coupled to and in fluid communication with a process gas supply 118. The process gas supply 118 may supply one or more process gases to the process chamber 100 for processing a substrate 122 disposed therein. A slit valve 148 may be coupled to the chamber body 106 and may be aligned with an opening in a sidewall of the chamber body 106 to facilitate transfer of the substrate 122 into and out of the chamber body 106.

[0028]

[0029] In use, the DC power supply 190 supplies power to the target 138 and other chamber components connected to the DC power supply 190, and in combination with the RF power supply 174, energizes the sputtering gas (e.g., from the process gas supply 118) to generate a plasma of the sputtering gas. The generated plasma impinges on the sputtering surface of the target 138, colliding with it and sputtering material from the target 138 onto the substrate 122. In some embodiments, the RF energy supplied by the RF power supply 174 may be in a frequency range within the VHF band (e.g., from about 30 to about 300 MHz). In some embodiments, multiple (i.e., two or more) RF power supplies may be provided to provide RF energy at multiple frequencies, including those outside the VHF band. An additional RF power supply (e.g., the RF bias power supply 117) may also be used to supply a bias voltage to the substrate support 124 to attract ions from the plasma toward the substrate 122.

[0029]

[0030] 2 shows a schematic side view of a process chamber 200 (e.g., a plasma processing chamber) configured for high-pressure plasma processing, according to at least some embodiments of the present disclosure. Process chamber 200 is similar to process chamber 100 described in FIG. 1, except as noted below.

[0030]

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

[0031]

[0032] In some embodiments, the ground return bracket 129 is generally bowl-shaped and has a recessed central portion 202 and a radially extending outer flange 204. In some embodiments, the radially extending outer flange is substantially planar (e.g., horizontal). The recessed central portion may further include a central opening 206 through which the hollow support shaft 112 and bellows assembly 110 may extend.

[0032]

[0033] The housing 208 of the pedestal 136 at least partially encloses an interior space 210 disposed below the electrostatic chuck 150 for positioning or routing other components of the substrate support 124. The housing includes a base 212 having a central opening coupled to the hollow support shaft 112 and a sidewall 214 extending from the base 212 to a backside of the electrostatic chuck 150. The ground return bracket 129 may contact or be coupled to the housing 208, for example, around the base 212. The bellows assembly 110 may be coupled to a lower portion of the base 212 around the hollow support shaft 112.

[0033]

[0034] The ground loop 172 may be disposed on or coupled to the ground return bracket 129 (e.g., the radially extending outer flange 204). For example, the ground loop 172 may be bolted or otherwise fastened along the outer periphery of the radially extending outer flange 204 by the plate 216 and the bolts 218. For example, in some embodiments, the dielectric plate 128 has an outer diameter that is larger than the outer diameter of the electrostatic chuck 150, the ground return bracket 129 (e.g., the radially extending outer flange 204) extends radially beyond the outer diameter of the dielectric plate 128, and the ground loop 172 is disposed on or coupled to the ground return bracket 129 (e.g., the radially extending outer flange 204) radially outward of the dielectric plate 128.

[0034]

[0035] The dielectric plate 128 is disposed between the ground return bracket 129 and the electrostatic chuck 150 to prevent ignition of plasma in this region. The dielectric plate 128 insulates the ground return bracket 129 from the process cavity and the electrostatic chuck 150. In some embodiments, the dielectric plate 128 is annular or otherwise includes a central opening sized to fit around the housing 208 of the pedestal 136 (e.g., the sidewall 214 of the housing 208). A plurality of through holes may be provided through the dielectric plate in the same direction (e.g., vertically) as the central opening for receiving fasteners 222, such as bolts, to secure the dielectric plate 128 to the ground return bracket 129 through corresponding openings in the ground return bracket 129.

[0035]

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

[0036]

[0037] While the forgoing is directed to several embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.

Claims

1. 1. An apparatus for high pressure plasma processing, comprising: Electrostatic chuck, a housing at least partially enclosing an interior space disposed directly below the electrostatic chuck; a ground return bracket spaced apart from the electrostatic chuck; and a dielectric plate disposed between the electrostatic chuck and the ground return bracket; The apparatus, wherein the dielectric plate includes a central opening sized to fit around the housing.

2. 10. The apparatus of claim 1, wherein the dielectric plate separates the electrostatic chuck from the ground return bracket by at least 10 mm.

3. The housing includes: Base, and The apparatus of claim 1 , further comprising a sidewall extending from the base to a backside of the electrostatic chuck.

4. The apparatus of claim 3 , further comprising a hollow support shaft, the base including 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 apparatus of claim 1 , wherein the ground return bracket is coupled to the housing.

6. 6. The apparatus of claim 1, wherein the ground return bracket is generally bowl-shaped and has a recessed central portion and a radially extending outer flange.

7. 7. The apparatus of claim 6, wherein the radially extending outer flange is substantially planar and the recessed central portion includes a central opening through which a hollow support shaft supporting the electrostatic chuck may extend.

8. The apparatus of claim 1 , further comprising a plurality of ground loops coupled to the ground return bracket.

9. 9. The apparatus of claim 8, wherein the dielectric plate has an outer diameter that is larger than an outer diameter of the electrostatic chuck, the ground return bracket extends radially beyond the outer diameter of the dielectric plate, and the plurality of ground loops are coupled to the ground return bracket radially outward of the dielectric plate.

10. 6. The apparatus of claim 1, further comprising a plurality of through holes through the dielectric plate for receiving fasteners for securing the dielectric plate to the ground return bracket through a plurality of corresponding openings in the ground return bracket.

11. 6. The apparatus of claim 1, further comprising aligned openings disposed through the dielectric plate, the ground return bracket, and the electrostatic chuck, the openings being positioned to facilitate movement of lift pins therethrough for raising and lowering a substrate relative to a support surface of the electrostatic chuck.

12. The housing further comprises a base having a central opening and a sidewall extending from the base to a back side of the electrostatic chuck; The device, a hollow support shaft coupled to the base about the central opening such that an interior of the hollow support shaft is coupled to the interior space, the ground return bracket being coupled to the housing and generally bowl-shaped and 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 The apparatus of claim 1 or 2, further comprising a plurality of ground loops coupled to the radially extending outer flange of the ground return bracket.

13. The housing includes a base having a central opening and a sidewall extending from the base to a back side of the electrostatic chuck within the central opening of the dielectric plate; The device, a hollow support shaft coupled to the base about the central opening such that an interior of the hollow support shaft is coupled to the interior space, the ground return bracket being coupled to the housing and generally bowl-shaped and 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 disposed through the dielectric plate, the ground return bracket, and the electrostatic chuck, the openings being positioned to facilitate movement of lift pins therethrough for raising and lowering a substrate relative to a support surface of the electrostatic chuck; and The apparatus of claim 2 , further comprising a plurality of ground loops coupled to the radially extending outer flange of the ground return bracket.

14. 1. A process chamber for high pressure plasma processing, comprising: a chamber body having an internal space therein; and A process chamber comprising the apparatus of any one of claims 1 to 5 disposed within the interior space.

15. The process chamber of claim 14 further comprising a target positioned within the interior space opposite the device.

16. 15. The process chamber of claim 14, further comprising a VHF RF source coupled to the process chamber for providing RF power in the VHF band to the process chamber.

17. The process chamber of claim 14, further comprising a plurality of ground loops coupled to the ground return bracket.

18. 18. The process chamber of claim 17, wherein the dielectric plate has an outer diameter that is greater than an outer diameter of the electrostatic chuck, the ground return bracket extends radially beyond the outer diameter of the dielectric plate, and the plurality of ground loops are coupled to the ground return bracket radially outward of the dielectric plate.

19. An apparatus for high pressure plasma processing, comprising: Electrostatic chuck, a ground return bracket spaced apart from the electrostatic chuck; a dielectric plate disposed between the electrostatic chuck and the ground return bracket; and a plurality of ground loops coupled to the ground return bracket; the dielectric plate has an outer diameter that is greater than an outer diameter of the electrostatic chuck, the ground return bracket extends radially beyond the outer diameter of the dielectric plate, and the plurality of ground loops are coupled to the ground return bracket radially outward of the dielectric plate.

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