Gas injection process kit to eliminate arcing and improve uniform gas distribution in PVD processes

Abstract

Described herein are embodiments of a process shield for use in a processing chamber. In some embodiments, the process shield for use in a processing chamber includes an annular body having an upper portion and a lower portion extending downward and radially inward from the upper portion, the upper portion including a plurality of annular trenches in an upper surface thereof, the plurality of annular trenches having a plurality of slots disposed therebetween for fluidly coupling the plurality of annular trenches, and one or more inlets extending from an outer surface of the annular body to an outermost trench of the plurality of annular trenches.

Description

Technical Field

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

Background Art

[0002] A plasma processing chamber typically includes a substrate support for supporting a substrate and a target disposed opposite the substrate support. The target serves as a source of material to be sputtered 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. The plasma processing chamber typically includes a processing kit for protecting the chamber walls from unwanted deposition and for confining the plasma. The processing kit generally includes a processing shield. The space between the target and the processing shield is called the dark space. During processing of the substrate for high-pressure processing (> 100 mTorr), contaminants such as gas-emitted particles may flow into the dark space, which may cause unwanted arc generation.

[0003] Therefore, the inventor provided an improved processing kit for use in a plasma processing chamber.

Summary of the Invention

[0004] This specification describes embodiments of a processing shield for use in a processing chamber. In some embodiments, the processing shield for use in a processing chamber includes an annular body having an upper portion and a lower portion extending downward and radially inward from the upper portion, the upper portion including a plurality of annular trenches on its upper surface, the plurality of annular trenches having a plurality of slots disposed between the plurality of annular trenches for fluidly coupling the plurality of annular trenches, and one or more inlets extending from the outer surface of the annular body to the outermost trench of the plurality of annular trenches.

[0005] In some embodiments, a processing kit for use in a processing chamber includes a processing shield having an upper part and a lower part extending downward and radially inward from the upper part, wherein the upper part includes a plurality of annular trenches on its upper surface, and the plurality of annular trenches have a plurality of slots arranged between the plurality of annular trenches to fluidly couple the plurality of annular trenches, and one or more inlets extending from the outer surface of the processing shield to the outermost trench of the plurality of annular trenches, and a covering having an annular body disposed on the processing shield.

[0006] In some embodiments, the processing chamber includes a chamber body having an internal volume therein, a substrate support disposed within the internal volume, a target disposed within the internal volume, the target positioned opposite the substrate support so as to at least partially define a processing space between the substrate support and the target, a processing shield disposed around the substrate support and the target to define the outer boundary of the processing space, the processing shield and the target defining a dark gap between them, the processing shield comprising a plurality of annular trenches, with a plurality of slots disposed between the plurality of annular trenches to fluidly couple the plurality of annular trenches to the dark gap, and a separation ring disposed between the target and the processing shield.

[0007] Other embodiments and additional embodiments of this disclosure are described below.

[0008] The embodiments of this disclosure, briefly outlined above and discussed in more detail later, can be understood by referring to the exemplary embodiments of this disclosure shown in the accompanying drawings. However, the accompanying drawings only illustrate typical embodiments of this disclosure and should therefore not be considered limiting, as this disclosure may accept other equally valid embodiments. [Brief explanation of the drawing]

[0009] [Figure 1]This is a schematic side view of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. [Figure 2] This is a schematic top view of a processing shield according to at least some embodiments of the present disclosure. [Figure 3] This is a side cross-sectional view of a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. [Figure 4] This is a side cross-sectional view of a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. [Modes for carrying out the invention]

[0010] For ease of understanding, the same reference numerals have been used to indicate identical elements common to the figures where possible. The figures are not drawn in proportion to the original text and may be simplified for clarity. Without specific mention, elements and features of one embodiment may be usefully incorporated into another embodiment.

[0011] This specification describes embodiments of a processing kit for use in a processing chamber. To prevent the undesirable accumulation of target material on the chamber walls, the processing kit includes a processing shield positioned around the target in the processing chamber. The space between the target and the processing shield is referred to as the dark area. Embodiments of the processing shield described herein advantageously include multiple gas channels through which gas flows into the dark area, thereby forming a gas curtain, which prevents contaminants from flowing into the dark area and causing undesirable arc generation. This gas may be a purge gas or one or more processing gases. If this gas includes one or more processing gases, these multiple gas channels advantageously improve the uniformity of the gas distribution within the processing chamber.

[0012] Figure 1 shows a schematic side view of a processing chamber 100 (e.g., a plasma processing chamber) having a processing kit according to at least some embodiments of the present disclosure. In some embodiments, the processing chamber 100 is a PVD (Physical Vapor Deposition) processing chamber for reactive processing. However, other types of processing chambers configured for different processing may also use embodiments of the processing kits described herein, or other types of processing chambers configured for different processing may be used with or modified to use embodiments of the processing kits described herein.

[0013] The processing chamber 100 is a vacuum chamber appropriately adapted to maintain a pressure lower than atmospheric pressure within an internal volume 120 during substrate processing. In some embodiments, the processing chamber 100 is suitable for processing substrates at pressures of about 1 milliliter to about 400 milliliters. In some embodiments, the processing chamber 100 is suitable for processing substrates at pressures of about 150 milliliters to about 350 milliliters. The processing chamber 100 includes a chamber body 106 covered by a lid assembly 104 that encloses a processing space 119 located in the upper half of the internal volume 120. The chamber body 106 and the lid assembly 104 may be made of a metal such as aluminum. The chamber body 106 can be grounded by coupling to ground 115.

[0014] Within the internal volume 120, a substrate support 124 is provided for supporting and holding a substrate 122, such as a semiconductor wafer or another substrate that can be held electrostatically. The substrate support 124 may generally include an electrostatic chuck 150 mounted 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 in which one or more electrodes 154 are disposed. The pedestal 136 is generally made of a metal such as aluminum. The pedestal 136 is biasable and can be maintained at an electrical stray potential or grounded during plasma operation. The hollow support shaft 112 provides a conduit for supplying, for example, backside gas, processing gas, fluid, coolant, power, etc., to the electrostatic chuck 150.

[0015] In some embodiments, a hollow support shaft 112 is coupled to a lift mechanism 113, such as an actuator or motor, which provides vertical movement of the electrostatic chuck 150 between an upper processing position (shown in Figure 1) and a lower transfer position (not shown). A bellows assembly 110 is positioned around the hollow support shaft 112, coupled between the electrostatic chuck 150 and the bottom surface 126 of the processing chamber 100 to provide a flexible seal, which allows vertical movement of the electrostatic chuck 150 and simultaneously prevents pressure loss from within the processing chamber 100. The bellows assembly 110 further includes a lower bellows flange 164, which contacts an O-ring 165 or other suitable sealing element that contacts the bottom surface 126 to help prevent chamber pressure loss.

[0016] The hollow support shaft 112 provides conduits 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 RF bias power supply 117 are coupled to the electrostatic chuck 150 via their respective corresponding RF matching circuits (only RF matching circuit 116 is shown). In some embodiments, the substrate support 124 may optionally include AC bias power or DC bias power.

[0017] The substrate lift 130 may include lift pins 109 mounted on a platform 108, the platform 108 being connected to a shaft 111, the shaft 111 being coupled to a second lift mechanism 132 for raising and lowering the substrate lift 130 to place the substrate 122 onto or remove the substrate 122 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 bottom surface 126 to provide a flexible seal that maintains chamber pressure while the substrate lift 130 is moving vertically.

[0018] Within the processing space 119, the target 138 is positioned facing the substrate support 124 such that the processing space 119 is at least partially defined between the target 138 and the substrate support 124. The substrate support 124 has a support surface having a plane substantially parallel to the sputtering surface of the target 138. In some embodiments, the target 138 is made of titanium, tantalum, or aluminum. The target 138 is connected to one or both of the DC power supply 190 and / or the RF power supply 174. The DC power supply 190 can apply a bias voltage to the target 138 relative to the processing shield 105.

[0019] The target 138 comprises a sputtering plate 142 mounted on a backing plate 144. The sputtering plate 142 contains the material to be sputtered onto the substrate 122. The backing plate 144 is manufactured from a metal such as stainless steel, aluminum, copper-chromium, or copper-zinc. The backing plate 144 can be manufactured from a material having a thermal conductivity large enough to dissipate the heat generated within the target 138, such heat being generated by eddy currents in the sputtering plate 142 and the backing plate 144, and further by the impact of high-energy ions from the generated plasma onto the sputtering plate 142. In some embodiments, the backing plate 144 includes a recess 146 on the side opposite to the sputtering plate 142.

[0020] In some embodiments, the processing chamber 100 includes a magnetic field generator 156 for shaping the magnetic field around the target 138 to improve sputtering of the target 138. Capacitively generated plasma can be enhanced by the magnetic field generator 156, which, for example, has multiple magnets 151 (e.g., permanent magnets or electromagnetic coils) that provide a magnetic field within the processing chamber 100 having a rotating magnetic field with a rotation axis perpendicular to the plane of the substrate 122. In addition to or instead of this, the processing chamber 100 may include a magnetic field generator 156 that generates a magnetic field near the target 138 to increase the ion density in the processing space 119 and improve sputtering of the target material. Multiple magnets 151 can be arranged in a cavity 153 of the lid assembly 104. To cool the target 138, a coolant such as water can be placed in the cavity 153, or a coolant such as water can be circulated through the cavity 153.

[0021] To prevent undesirable reactions between various chamber components and the ionized processing material, the processing chamber 100 includes a processing kit 102 positioned at the boundaries of such chamber components. To at least partially define the processing space 119, the processing kit 102 includes a processing shield 105 surrounding a substrate support 124 and a target 138. For example, the processing shield 105 can define the outer boundary of the processing space 119. The outer circumferential surface of the target 138 and the processing shield 105 define a dark gap 194 between the target 138 and the processing shield 105. The dark gap 194 is configured to prevent arc generation between the target 138 and the processing shield 105. In some embodiments, the processing shield 105 is made of a metal such as aluminum. In some embodiments, the processing kit 102 includes a deposition ring 170 resting on the outer edge of an electrostatic chuck 150. In some embodiments, the processing kit 102 includes a covering 180, which is positioned on the processing shield 105 to form a meandering gas flow path between the covering 180 and the processing shield 105.

[0022] The processing chamber 100 is coupled to and fluidly connected to a vacuum system 184, which includes a throttle valve (not shown) and a pump (not shown) used to evacuate the processing chamber 100. The pressure inside the processing chamber 100 can be adjusted by adjusting the throttle valve and / or the pump. To facilitate the transfer of the substrate 122 into and out of the chamber body 106, a slit valve 148 is coupled to the chamber body 106, and the slit valve 148 can be aligned with an opening in the side wall of the chamber body 106.

[0023] The processing chamber 100 is coupled to a first gas supply 192, which is configured to supply one or more gases into the dark gap 194 through the processing shield 105 to favorably form a gas curtain, which prevents gas from being released from the substrate 122 during processing into the dark gap 194 and causing undesirable arc generation. The first gas supply 192 can supply a purge gas or one or more processing gases. In some embodiments, the first gas supply 192 can supply nitrogen gas, argon gas, or oxygen gas. In some embodiments, the processing chamber 100 can also be coupled to a second gas supply 118 which can supply one or more processing gases to the processing chamber 100 from below the chamber body 106 (i.e., from below the substrate 122) to process the substrate 122 placed inside the processing chamber 100, and the processing chamber 100 can also be fluidly coupled to the second gas supply 118. For example, while the second gas supply 118 is supplying argon gas, the first gas supply 192 can supply nitrogen gas or oxygen gas.

[0024] During use, while the DC power supply 190 supplies power to the target 138 and other chamber components connected to the DC power supply 190, the RF power supply 174 supplies power to the sputtering gas (e.g., from the first gas supply 192 or the second gas supply 118) to form a plasma of the sputtering gas. The formed plasma impinges on the sputtering surface of the target 138, impacts the sputtering surface of the target 138, sputters the material of the target 138, and deposits it on the substrate 122. In some embodiments, the frequency of the RF energy supplied by the RF power supply 174 can be in the range of about 2 MHz to about 60 MHz, or non-limiting frequencies such as, for example, 2 MHz, 13.56 MHz, 27.12 MHz, or 60 MHz can be used. In some embodiments, a plurality (i.e., two or more) of RF power supplies can be provided to supply RF energy at the above-mentioned plurality of frequencies. An additional RF power supply (e.g., the RF bias power supply 117) can also be used to apply a bias voltage to the substrate support 124 to attract ions from the plasma towards the substrate 122.

[0025] FIG. 2 shows a side cross-sectional view of a portion of a processing chamber having a processing kit, according to at least some embodiments of the present disclosure. The processing kit 102 includes a processing shield 105, which generally has an annular body 202 including an upper portion 206 and a lower portion 208 extending downward and radially inward from the upper portion 206. In some embodiments, the upper portion 206 includes a coolant channel 230 for circulating coolant therethrough to cool the processing shield 105.

[0026] A separation ring 210 is disposed between the target 138 and the processing shield 105. In some embodiments, the upper surface 212 of the upper portion 206 includes a recess 228 for accommodating the separation ring 210. In some embodiments, the upper portion 206 includes a plurality of annular trenches 204 on its upper surface 212. In some embodiments, the plurality of annular trenches 204 extend downward from the recess 228. In order to accommodate an O-ring 238 or other suitable sealing gasket for sealing between the separation ring 210 and the processing shield 105, in some embodiments, the upper portion 206 includes an O-ring groove 232 radially outside the plurality of annular trenches 204.

[0027] The processing shield 105 includes one or more inlets 218 that extend from the outer surface 214 of the processing shield 105 to the outermost trench 220 of the plurality of annular trenches 204. The one or more inlets 218 are fluidly coupled to the first gas supply 192 for supplying gas from the first gas supply 192 to the plurality of annular trenches 204. The processing shield 105 includes a plurality of slots (discussed later with respect to FIG. 3) to fluidly couple the plurality of annular trenches 204 and provide a gas flow path from the one or more inlets 218 to the innermost trench 222.

[0028] In some embodiments, the multiple annular trenches 204 include a second trench 224 and a third trench 226 positioned between the outermost trench 220 and the innermost trench 222. In some embodiments, each trench in the multiple annular trenches 204 has a width of approximately 0.05 inches to approximately 0.2 inches. In some embodiments, each trench in the multiple annular trenches 204 has a depth of approximately 0.3 inches to approximately 0.4 inches. Figure 2 shows a multiple annular trenches 204 containing four trenches, but the multiple annular trenches 204 may also contain five or more trenches or three or fewer trenches. In some embodiments, all trenches in the multiple annular trenches 204, except for the innermost trench 222, are positioned directly beneath the separation ring 210. In some embodiments, all trenches in the multiple annular trenches 204 have substantially similar widths and depths. In some embodiments, substantially similar or approximately may be within approximately 10 percent.

[0029] Figure 3 shows a schematic top view of a processing shield 105 according to at least some embodiments of the present disclosure. A first gas supply 192 is fluid-coupled to one or more inlets 218. In some embodiments, one or more inlets 218 include four inlets extending to the outermost trench 220. To fluid-couple the outermost trench 220 to the innermost trench 222, the processing shield 105 includes a plurality of slots 306 between each of the annular trenches of a plurality of annular trenches 204. In some embodiments, an inner ring 250 of the processing shield 105, positioned radially inward of the innermost trench 222, has a continuous surface facing the processing space.

[0030] In some embodiments, the multiple slots 306 are arranged to provide substantially equal flow paths from one or more inlets 218 to the innermost trench 222. In some embodiments, the number of multiple slots 306 between adjacent annular trenches of multiple annular trenches 204 increases from the outermost trench 220 to the innermost trench 222. In some embodiments, the number of multiple slots 306 between adjacent annular trenches of multiple annular trenches 204 doubles from the outermost trench 220 to the innermost trench 222.

[0031] For example, in some embodiments, the multiple slots 306 include eight slots between the outermost trench 220 and the second trench 224. In some embodiments, the eight slots between the outermost trench 220 and the second trench 224 are spaced at equal intervals. In some embodiments, the multiple slots 306 include sixteen slots between the second trench 224 and the third trench 226. In some embodiments, the sixteen slots between the second trench 224 and the third trench 226 are spaced at equal intervals. In some embodiments, the multiple slots 306 include thirty-two slots between the third trench 226 and the innermost trench 222. In some embodiments, the thirty-two slots between the third trench 226 and the innermost trench 222 are spaced at equal intervals.

[0032] Returning to Figure 2, a first gap 240 is located between the inner surface of the separation ring 210 and the outer surface of the inner ring 250 of the upper 206 (i.e., the opposing surface of the processing shield 105). The first gap 240 is fluidly coupled to the innermost trench 222. For example, the first gap 240 can be located above the innermost trench 222 such that the open bottom of the first gap 240 coincides with at least a portion of the open top of the innermost trench 222. In some embodiments, the first gap 240 has a width smaller than the width of the innermost trench 222. In some embodiments, the first gap is about 0.02 inches to about 0.1 inches. A second gap 242 is located between the upper surface of the inner ring 250 and the target 138. A dark gap 194 is located between the inner surface of the inner ring 250 and the target 138. A flow path extends from the first gas supply 192 into the processing space 119 through one or more inlets 218, a plurality of annular trenches 204, a first gap 240, a second gap 242, and a dark gap 194. The first gap 240 is maintained at a substantially uniform distance along the perimeter of the processing shield 105 to advantageously provide a more uniform gas distribution into the processing space 119, and thus a more uniform mixing of the gas supplied by the first gas supply 192 and the target material. In embodiments where the first gap 240 has a width smaller than the width of the innermost trench 222, the first gap 240 restricts the flow to advantageously provide a more uniform gas distribution into the processing space 119, and thus a more uniform mixing of the gas supplied by the first gas supply 192 and the target material.

[0033] In some embodiments, the lower part 208 includes a first leg 244 extending downward from the upper part 206. In some embodiments, the lower part 208 includes a first ledge 246 extending radially inward from the first leg 244. In some embodiments, the lower part 208 includes an inner lip 248 extending upward from the first ledge 246. In some embodiments, the first leg 244 does not have a through hole. In some embodiments, the inner lip 248 does not have a through hole.

[0034] In some embodiments, a covering 180 is positioned on the processing shield 105. The covering 180 generally includes an annular body 252 having a lower groove 254 on its underside for accommodating an inner lip 248. In some embodiments, the inner lip 248 and the lower groove 254 form a meandering gas channel. In some embodiments, the upper surface 216 of the covering 180 is inclined downward and radially inward. The covering 180 and the deposition ring 170 form a meandering gas channel between them.

[0035] Figure 4 shows a side section view of a portion of a processing chamber having a processing kit according to at least some embodiments of the present disclosure. In some embodiments, one or more centering bushings 410 are coupled to the processing shield 105 to position the covering 180 in the center of the processing shield 105. In some embodiments, the covering 180 includes outer legs 416 and inner legs 426 extending downward from the annular body 252 on both sides of the lower groove 254. In some embodiments, the outer legs 416 include one or more slots 420 for accommodating one or more centering bushings 410. In some embodiments, one or more centering bushings 410 include three bushings. In some embodiments, one or more centering bushings 410 are arranged at equal intervals. In some embodiments, one or more centering bushings 410 are coupled to the processing shield 105 by fasteners 430. In some embodiments, one or more centering bushings 410 extend into the opening 450 of the first ledge 246.

[0036] In some embodiments, one or more centering bushings 410 have a rounded top surface. In some embodiments, one or more slots 420 have angled sidewalls 424. In some embodiments, the angled sidewalls of one or more slots 420 extend downward and outward at an angle of about 5 to about 15 degrees. The angled sidewalls of one or more slots 420 and the rounded top surface of one or more centering bushings 410 advantageously allow for repeatable concentric arrangement and enable concentric thermal expansion of the covering 180 relative to the processing shield 105. In some embodiments, one or more centering bushings 410 have a diameter of about 0.3 to about 0.5 inches to advantageously minimize interruptions to the meandering gas flow path between the processing shield 105 and the covering 180.

[0037] While the above description applies to embodiments of the present disclosure, other embodiments and additional embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. 1. A process shield for use in a process chamber, comprising:

1. A process shield comprising: an annular body having an upper portion and a lower portion extending downwardly and radially inwardly from the upper portion, the upper portion including a plurality of trenches in an upper surface thereof, the plurality of trenches having a plurality of slots disposed therebetween for fluidly coupling the plurality of trenches, and one or more inlets extending from an outer surface of the annular body to an outermost one of the plurality of trenches.

2. 2. The process shield of claim 1, wherein a number of the plurality of slots between adjacent annular trenches of the plurality of trenches increases from the outermost trench to the innermost trench.

3. 3. The process shield of claim 2, wherein the plurality of trenches includes a second trench and a third trench disposed between the outermost trench and the innermost trench, and the plurality of slots includes 8 slots between the outermost trench and the second trench, 16 slots between the second trench and the third trench, and 32 slots between the third trench and the innermost trench.

4. The process shield of claim 1 , wherein the one or more inlets comprises four inlets.

5. The process shield of claim 1 , wherein the top surface of the annular body includes a recess, and the plurality of trenches extend downwardly from the recess.

6. The process shield of any of claims 1 to 5, wherein the top portion comprises coolant channels.

7. The process shield of any of claims 1 to 5, wherein the plurality of trenches have a width of about 0.2 inches to about 0.05 inches.

8. The process shield of any of claims 1 to 5, wherein the top portion includes an O-ring groove radially outward of the plurality of trenches.

9. 6. The process shield of claim 1, wherein the lower portion includes a first leg extending downwardly from the upper portion, a first ledge extending radially inward from the first leg, and an inner lip extending upwardly from the first ledge, the first leg being devoid of through holes.

10. The process shield of any of claims 1 to 5, wherein a number of the plurality of slots between adjacent annular trenches of the plurality of trenches increases from the outermost trench to the innermost trench.

11. 1. A process kit for use in a process chamber, comprising: The treatment shield according to any one of claims 1 to 5, a cover ring having an annular body disposed on the process shield; A processing kit comprising:

12. The process kit of claim 11 , further comprising one or more centering bushings coupled to the process shield for centering the cover ring on the process shield.

13. The process kit of claim 12 , wherein the cover ring includes an outer leg and an inner leg extending downwardly from the annular body, the outer leg including one or more slots for receiving the one or more centering bushings.

14. The process kit of claim 11 , wherein the one or more centering bushings comprises three bushings.

15. a chamber body having an interior volume therein; a substrate support disposed within the interior volume; a target disposed within the interior volume, the target disposed opposite the substrate support to at least partially define a process space between the substrate support and the target; a substrate support and a target disposed about the substrate support and the target to define an outer boundary of the processing space; 6. A process shield according to claim 1, wherein the process shield and the target define a dark space gap therebetween, and the plurality of trenches of the process shield are coupled to the dark space gap; an isolation ring disposed between the target and the process shield; A processing chamber comprising:

16. 16. The processing chamber of claim 15, further comprising a first gas supply, the first gas supply for flowing one or more gases from the first gas supply through the plurality of trenches to the dark space gap.

17. 16. The processing chamber of claim 15, further comprising a second gas supply configured to supply one or more process gases to the processing chamber from a lower portion of the chamber body.

18. 16. The processing chamber of claim 15, wherein the process shield includes a recess on an upper surface thereof, the plurality of trenches extending from the recess, and the isolation ring disposed within the recess.

19. The processing chamber of claim 15 , wherein the processing shield includes a coolant channel configured to flow a coolant therethrough.

20. 16. The processing chamber of claim 15, wherein a gap between an inner surface of the isolation ring and an opposing surface of the process shield is between about 0.02 inches and about 0.1 inches.

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