Electrostatic chuck with improved thermal coupling for temperature sensitive processes

Abstract

To provide a substrate support for use in processing equipment.SOLUTION: Embodiments of an electrostatic chuck (ESC) having internal gas channels to improve thermal coupling between the ESC and a substrate, and a substrate support and process chamber incorporating the ESC, are provided herein. In some embodiments, an electrostatic chuck includes an electrode, a dielectric body having a disc shape and covering the electrode, the dielectric body including a central region and a peripheral region, the dielectric body including a lower surface having a central opening and an upper surface having a first opening in the central region and a plurality of second openings in the peripheral region, the upper surface including a plurality of protrusions, a diameter of each of the plurality of second openings being greater than 25.0 mils, and a gas distribution channel extending from the lower surface to the upper surface to define a plenum within the dielectric body.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE Embodiments of the present disclosure relate generally to substrate processing equipment, and more particularly to substrate supports used in processing equipment. [Background technology]

[0002] Deposition chambers, such as physical vapor deposition (PVD) chambers, are often used to form thin film layers on substrates. The deposition process requires high vacuum pressure. Electrostatic chucks are often used to electrostatically hold the substrate on the substrate support during the deposition process. Electrostatic chucks typically include a dielectric body with one or more electrodes disposed thereon. Electrostatic chucks can have one or more heaters embedded therein to provide thermal coupling to the substrate when it is positioned on the electrostatic chuck.

[0003] However, the present inventors have observed that certain deposition processes are highly temperature sensitive. Accordingly, the present inventors provide an improved apparatus for depositing materials via physical vapor deposition having improved thermal coupling between the electrostatic chuck and the substrate. Summary of the Invention

[0004]

[0003] Embodiments of an electrostatic chuck (ESC) having internal gas channels for improving thermal coupling between the ESC and the substrate, as well as a substrate support and a process chamber incorporating the ESC, are provided herein. In some embodiments, the electrostatic chuck includes an electrode, a disk-shaped dielectric covering the electrode, the dielectric including a lower surface having a central opening and an upper surface having a first opening in the central region and a plurality of second openings in the peripheral region, the upper surface including a plurality of protrusions, each of the plurality of second openings having a diameter greater than 25.0 mils, gas distribution channels extending from the lower surface to the upper surface to define a plenum within the dielectric, the gas distribution channels including a first channel extending from the central opening to the first opening, a plurality of radial channels extending from the first channel to an annular channel disposed in the peripheral region, and a plurality of second channels extending from the annular channel to the plurality of second openings, and a heater disposed within the dielectric.

[0005] In some embodiments, the substrate support includes a hollow shaft and a pedestal, the pedestal including: a housing coupled to the hollow shaft; a dielectric covering the electrode, the dielectric being coupled to the housing and including an upper surface having a first opening in a central region of the dielectric and a plurality of second openings in a peripheral region of the dielectric, and a lower surface having a central opening; a plenum including a first channel extending from the central opening to the first opening, a plurality of radial channels extending from the first channel to an annular channel disposed in the peripheral region, and a plurality of second channels extending from the annular channel to the plurality of second openings, wherein a length of the plurality of second channels from the annular channel to the plurality of second openings is greater than 120.0 mils; and one or more heating elements disposed within the dielectric.

[0006] In some embodiments, the process chamber includes a chamber body; a substrate support disposed within the chamber body and having a pedestal coupled to a hollow shaft, the pedestal having a dielectric covering an electrode, the dielectric including an upper surface and a lower surface, the upper surface configured to receive a substrate, the upper surface having a first opening in a central region of the dielectric and a plurality of second openings in a peripheral region of the dielectric, the lower surface having a central opening, each of the plurality of second openings having a diameter greater than 25.0 mils; a heater disposed within the dielectric; a gas conduit disposed outside the chamber body extending from a gas supply to the central opening; and a gas distribution channel extending from the central opening to the plurality of second openings, the gas distribution channel being in fluid communication with the gas conduit. In some embodiments, the process chamber can be a physical vapor deposition (PVD) process chamber.

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

[0008] Embodiments of the present disclosure, briefly summarized above and discussed in more detail below, can be understood by reference to exemplary embodiments thereof as illustrated in the accompanying drawings. However, because the present disclosure is applicable to 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] FIG. 1 is a schematic side view of a process chamber having an electrostatic chuck in accordance with at least some embodiments of the present disclosure. [Figure 2] FIG. 1 illustrates a top view of a substrate support in accordance with at least some embodiments of the present disclosure. [Figure 3] 1 is a schematic side view of a substrate support according to at least some embodiments of the present disclosure. [Figure 4] FIG. 3 is a cross-sectional top view of the electrostatic chuck of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] For ease of understanding, the same reference numerals have been used, where possible, to refer to identical elements common to the figures. The figures are not drawn 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] Provided herein are embodiments of an electrostatic chuck (ESC) having an internal gas channel to improve thermal coupling between the ESC and a substrate, as well as a substrate support and a process chamber incorporating the ESC. The internal gas channel can extend from a single inlet disposed on a lower surface of the ESC to multiple outlets disposed on an upper surface of the ESC. The single inlet is coupled to a backside gas supply including, for example, argon (Ar), helium (He), or the like. The backside gas flows through the internal gas channel, advantageously improving thermal coupling between the ESC and the substrate and providing improved temperature uniformity across the substrate when heated. The internal gas channel extending from a single inlet to multiple outlets on the upper surface of the ESC provides easier connection to a single backside gas supply line compared to multiple backside gas supply lines coupled to multiple outlets on the upper surface of the ESC.

[0012] 1 is a schematic cross-sectional view of a process chamber (e.g., a plasma processing chamber) according to some embodiments of the present disclosure. In some embodiments, the plasma processing chamber is a physical vapor deposition (PVD) processing chamber. However, other types of processing chambers configured for different processes can also be used with or modified for use with the electrostatic chuck embodiments described herein.

[0013] The chamber 100 is a vacuum chamber suitably adapted to maintain a subatmospheric pressure within a chamber interior volume 120 during substrate processing. The chamber 100 includes a chamber body 106 covered by a lid 104 that encloses a process volume 119 located in the upper half of the chamber interior volume 120. The chamber 100 may also include one or more shields 105 that circumscribe various chamber components to prevent undesired reactions between such components and ionized process materials. The chamber body 106 and lid 104 may be made from a metal such as aluminum. The chamber body 106 may be grounded via a bond to ground 115.

[0014] A substrate support 124 is disposed within the chamber interior volume 120 to support and hold a substrate 122, such as, for example, a semiconductor wafer or other substrate that can be electrostatically held. The substrate support 124 may generally include a pedestal 136 having an electrostatic chuck 150 (described in more detail below with respect to FIGS. 2-4 ) and a hollow support shaft 112 for supporting the electrostatic chuck 150. The electrostatic chuck 150 includes a dielectric body on which one or more electrodes 154 are disposed. 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.

[0015] 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 (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 bottom surface 126 of the chamber 100 to provide a flexible seal that prevents loss of vacuum from within the chamber 100 while allowing vertical movement of the electrostatic chuck 150. 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 bottom surface 126 to help prevent loss of chamber vacuum.

[0016] The hollow support shaft 112 provides conduits for coupling a backside gas supply 141, a chuck power supply 140, and RF sources (e.g., an RF plasma power supply 170 and an RF bias power supply 117) to the electrostatic chuck 150. In some embodiments, the RF energy supplied by the RF plasma power supply 170 can have a frequency of about 40 MHz or greater. The backside gas supply 141 is disposed outside the chamber body 106 and supplies a heat transfer gas to the electrostatic chuck 150. In some embodiments, the RF plasma power supply 170 and the RF bias power supply 117 are coupled to the electrostatic chuck through respective RF match networks (only the RF match network 116 is shown). In some embodiments, the substrate support may alternatively include AC, DC, or RF bias power.

[0017] A substrate lift 130 can include lift pins 109 mounted on a platform 108 connected to a shaft 111, which is coupled to a second lift mechanism 132 for raising and lowering the substrate lift 130 so that the substrate 122 can be placed on or removed from the electrostatic chuck 150. The electrostatic chuck 150 includes 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 vacuum during vertical movement of the substrate lift 130.

[0018] The electrostatic chuck 150 includes a gas distribution channel 138 that extends from the lower surface of the electrostatic chuck 150 to various openings in the upper surface of the electrostatic chuck 150. The gas distribution channel 138 is fluidly connected to a backside gas supply 141 via a gas conduit 142. The gas distribution channel 138 extends below the electrode 154. The pedestal 136 includes one or more heaters. For example, in some embodiments, the pedestal 136 includes an inner heater 144 having one or more resistive heating elements 308 configured to provide heat to an inner portion of the pedestal 136. In some embodiments, the pedestal 136 can further include an outer heater 148 disposed within a peripheral region of the pedestal 136 and configured to provide heat to an outer portion of the pedestal 136. The outer heater 148 includes one or more resistive heating elements 310. The hollow support shaft 112 further includes a power source (e.g., an AC power source 162) coupled to the inner heater 144 via a first lead 172 to supply power to the heating element of the inner heater 144. The AC power source 162 can also supply power to the heating element of the outer heater 148 via a second lead 174. Alternatively, the second lead 174 can be coupled to a power source that is independent of the power source coupled to the inner heater 144. In some embodiments, the inner heater 144 is disposed within a central region of the pedestal 136. In some embodiments, the outer heater 148 is disposed within a peripheral region of the pedestal 136. The power applied by the power source to the inner heater 144 can be different from the power applied to the outer heater 148. Thus, in some embodiments, the substrate support 124 includes dual-zone temperature control.

[0019] Chamber 100 is coupled to and in fluid communication with a vacuum system 114, which includes a throttle valve (not shown) and a vacuum pump (not shown) used to evacuate chamber 100. By adjusting the throttle valve and / or the vacuum pump, the pressure within chamber 100 can be adjusted. Chamber 100 is also coupled to and in fluid communication with a process gas supply 118, which can supply one or more process gases to chamber 100 for processing a substrate disposed within chamber 100.

[0020] For example, during operation, a plasma 102 can be generated within the chamber internal volume 120 to perform one or more processes. The plasma 102 can be generated by coupling power from a plasma power source (e.g., RF plasma power source 170) to a process gas through one or more electrodes 154 near or within the chamber internal volume 120, igniting the process gas and generating the plasma 102. In some embodiments, bias power can be provided from a bias power source (e.g., RF bias power source 117) to one or more electrodes 154 within the electrostatic chuck 150 via capacitively coupled bias plates (described below) to attract ions from the plasma toward the substrate 122. The electrostatic chuck can have a specific thickness above the electrode. This thickness can be based on a specification that specifies an allowable thickness range above the electrode. For a Johnsen-Rahbek (JR) type electrostatic chuck, this thickness can be approximately 200-300 μm. Alternatively, the specification can describe the allowable thickness of the electrostatic chuck.

[0021] In some embodiments, for example when chamber 100 is a PVD chamber, a target 166 containing a source material for deposition on substrate 122 can be positioned above the substrate within chamber internal volume 120. Target 166 can be supported by a grounded conductive portion of chamber 100, for example, an aluminum adapter that passes through a dielectric isolator. In other embodiments, chamber 100 can include multiple targets in a multi-cathode arrangement to deposit layers of different materials using the same chamber.

[0022] A controllable DC power supply 168 may be coupled to the chamber 100 to apply a negative voltage or bias to the target 166. An RF bias power supply 117 may be coupled to the substrate support 124 to induce a negative DC bias with respect to the substrate 122. Additionally, in some embodiments, a negative DC self-bias may be formed on the substrate 122 during processing. In some embodiments, an RF plasma power supply 170 may also be coupled to the chamber 100 to apply RF power to the target 166 to facilitate control of the radial distribution of the deposition rate on the substrate 122. During operation, ions of the plasma 102 created in the chamber 100 react with the source material from the target 166. This reaction causes the target 166 to release atoms of the source material, which are then directed toward the substrate 122, thus depositing the material.

[0023] 2 illustrates a top view of an electrostatic chuck in accordance with at least some embodiments of the present disclosure. The electrostatic chuck includes an upper surface 204. One or more through-holes 216 extend through the electrostatic chuck 150 to accommodate the lift pins 109. As shown in FIG. 2, the electrostatic chuck 150 includes three through-holes 216 disposed within a peripheral region of the electrostatic chuck. The upper surface includes a first opening 208 disposed within a central region of the electrostatic chuck 150. In some embodiments, the upper peripheral portion of the electrostatic chuck 150 includes a notch that defines a lower fillet 214 parallel to the upper surface 204.

[0024] The upper surface includes a plurality of second openings 210 disposed within a peripheral region of the electrostatic chuck 150. As shown in FIG. 2 , the plurality of second openings 210 includes eight second openings disposed at regular intervals (e.g., equidistant from one another) around the first opening 208. In some embodiments, the plurality of second openings 210 are disposed in a single annular pattern around the first opening 208 (e.g., along a common diameter). In some embodiments, the plurality of second openings 210 are disposed about 200.0 mm to about 280.0 mm from the first opening 208. In some embodiments, the plurality of second openings 210 are disposed about 220.0 mm to about 260.0 mm from the first opening 208. In some embodiments, the plurality of second openings 210 are disposed in multiple annular patterns around the first opening 208 (e.g., along multiple different diameters). 2 shows eight second apertures, the plurality of second apertures 210 may include more or fewer apertures. For example, in some embodiments, the plurality of second apertures 210 may include four apertures. In some embodiments, the plurality of second apertures 210 may include sixteen apertures.

[0025] The top surface 204 includes a plurality of protrusions 206 extending therefrom. The plurality of protrusions 206 define recesses 212 between the protrusions 206. The recesses 212 are configured to flow a backside gas across the top surface 204 of the electrostatic chuck 150 while a substrate is disposed on the substrate receiving surface 228 to advantageously improve thermal coupling between the substrate 122 and the electrostatic chuck 150. The protrusions 206 can have various shapes and can be different sizes. In some embodiments, the size and shape of the protrusions 206 vary across the electrostatic chuck 150. The protrusions 206 (e.g., the top surfaces of the protrusions 206) together define the substrate receiving surface 228. The depth, width, and density of the protrusions 206 are designed to enhance uniform gas distribution across the electrostatic chuck 150. In some embodiments, to advantageously provide improved thermal coupling to the peripheral region of the electrostatic chuck 150, the first set of protrusions 226 in the central region of the electrostatic chuck 150 have a greater surface area or density than the second set of protrusions 218 in the peripheral region of the electrostatic chuck 150.

[0026] The electrostatic chuck 150 includes a first thermocouple opening 220 in a central region of the electrostatic chuck 150. In some embodiments, the electrostatic chuck 150 includes a second thermocouple opening 222 in the central region of the electrostatic chuck 150. In some embodiments, the first thermocouple opening 220 and the second thermocouple opening 222 are disposed near the first opening 208. In some embodiments, the first thermocouple opening 220 and the second thermocouple opening 222 are disposed opposite each other around the first opening 208. In some embodiments, the electrostatic chuck 150 includes a third thermocouple opening 224 at an interface between the central region and the peripheral region of the electrostatic chuck 150.

[0027] The first thermocouple opening 220, the second thermocouple opening 222, and the third thermocouple opening 224 can accommodate thermocouples that can be embedded in the electrostatic chuck 150 and used to monitor the temperature of the electrostatic chuck 150. For example, signals from the thermocouples can be used in a feedback loop to control the power applied by the AC power supply 162 to the inner heater 144 and the outer heater 148. Having both the first thermocouple opening 220 and the second thermocouple opening 222 in the central region advantageously provides redundant temperature monitoring and allows for more accurate temperature measurements for the feedback loop. Having the third thermocouple opening 224 at or near the peripheral region provides temperature monitoring in the peripheral region, which is advantageous for substrate supports having multiple heaters.

[0028] FIG. 3 shows a schematic side view of the substrate support. The substrate support 124 includes a pedestal 136 having a bottom 316 and a sidewall 318 extending upwardly from the bottom 316. The bottom 316 and the sidewall 318 form a housing for the pedestal 136. The electrostatic chuck 150 is located on the sidewall 318. Shading is not shown in the schematic side view of the electrostatic chuck 150 to avoid obscuring details. The bottom 316 is coupled to the hollow support shaft 112. A cooling plate 328 is coupled to the bottom 316 via fasteners 336. The cooling plate 328 is configured to cool the electrostatic chuck 150 to advantageously reduce the cooling time of the electrostatic chuck 150 before any maintenance can be performed on the chamber 100.

[0029] The electrostatic chuck 150 includes a central region 312 and a peripheral region 320. In some embodiments, the central region has a diameter of about 150.0 mm to about 210.0 mm. The peripheral region 320 extends from the outer edge of the central region to the outer edge of the electrostatic chuck 150. The electrostatic chuck 150 includes a lower surface 306 opposite the upper surface 204. The lower surface 306 includes a central opening 302 disposed within the central region 312. A first channel 324 extends from the central opening 302 in the lower surface 306 to a first opening 208 in the upper surface 204. The first channel 324 is fluidly coupled to the gas conduit 142. A radial channel 234 extends from the first channel 324 to an annular channel 240 disposed within the peripheral region 320. A plurality of second channels 330 extend from the annular channel 240 to the plurality of second openings 210. In some embodiments, the first channel 324 has a diameter similar to the second channel 330. In some embodiments, the first channel 324 has a diameter larger than the diameter of the second channel 330. The radial channel 234 and the annular channel 240 are disposed below the electrode 154. Therefore, the chucking force of the electrode 154 is not affected by the depth of the gas distribution channel 138. In some embodiments, the length of the plurality of second channels 330 from the annular channel 240 to the plurality of second openings 210 is greater than 120.0 mils. In some embodiments, the length of the plurality of second channels 330 is between about 160.0 mils and about 200.0 mils.

[0030] The gas distribution channel 138 includes a plenum 322 defined by a first channel 324, a radial channel 234, an annular channel 240, and a plurality of second channels 330. The plurality of second channels 330, together with the first channel 324, advantageously distribute backside gas evenly across the top surface 204 of the electrostatic chuck 150. The plurality of second openings 210 and the first openings 208 are large enough for improved gas conductance, yet small enough to suppress gas ignition. In some embodiments, the diameter of each of the plurality of second openings 210 and the first openings 208 is greater than 25.0 mils, thereby allowing the backside gas to flow to the top surface 204 at a suitable rate for improved gas conductance. In some embodiments, the diameter of each of the plurality of second openings is between about 36.0 mm and about 42.0 mm.

[0031] 4 shows a cross-sectional top view of the electrostatic chuck of FIG. 2. As shown in FIG. 4, the gas distribution channel 138 includes four radial channels 234 extending from the first channel 324 to the annular channel 240. Each of the four radial channels 234 extends radially outward approximately 90 degrees from an adjacent radial channel 234. In some embodiments, the radial channels 234 join the annular channel 240 at positions corresponding to the second channels 330. In some embodiments, the radial channels 234 join the annular channel 240 at positions that do not correspond to the second channels 330. For example, in some embodiments, the electrostatic chuck 150 includes eight second channels 330 and four radial channels 234, with each radial channel 234 extending between adjacent second channels 330. In some embodiments, the radial channels 234 extend approximately halfway between adjacent second channels 330, such that the distance between each second channel 330 is equidistant from the nearest radial channel 234, allowing backside gas to flow more uniformly to all of the second channels 330. Advantageously, the annular channel 240 allows the number of second channels 330 to be greater than the number of radial channels 234.

[0032] While the forgoing is directed to embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof.

Claims

1. An electrode; a dielectric having a disk shape and covering the electrode, the dielectric including a central region and a peripheral region, the dielectric including a lower surface having a central opening, and an upper surface having a first opening in the central region and a plurality of second openings in the peripheral region, the upper surface including a plurality of protrusions, each of the plurality of second openings having a diameter greater than 25.0 mils; gas distribution channels extending from the lower surface to the upper surface to define a plenum within the dielectric, the gas distribution channels including a first channel extending from the central opening to the first opening, a plurality of radial channels extending from the first channel to an annular channel disposed in the peripheral region, and a plurality of second channels extending from the annular channel to the plurality of second openings; a heater disposed within the dielectric; An electrostatic chuck comprising:

2. The electrostatic chuck of claim 1 , wherein each of the plurality of radial channels extends between adjacent second channels.

3. 3. The electrostatic chuck of claim 2, wherein the plurality of second openings comprises eight second openings spaced at regular intervals along the peripheral region equidistant from the first openings.

4. The electrostatic chuck of claim 3 , wherein the plurality of radial channels comprises four radial channels.

5. 5. The electrostatic chuck of claim 1, wherein a length of the plurality of second channels from the annular channel to the plurality of second openings is greater than 120.0 mils.

6. 5. The electrostatic chuck of claim 1, wherein the plurality of protrusions define a substrate receiving surface and a recess between the protrusions, the recess configured to allow gas to flow across the dielectric while a substrate is disposed on the plurality of protrusions.

7. 7. The electrostatic chuck of claim 6, wherein the plurality of protrusions includes a first set of protrusions disposed in the central region of the electrostatic chuck, the first set of protrusions having a larger surface area than a second set of protrusions disposed in the peripheral region of the electrostatic chuck.

8. The electrostatic chuck of any one of claims 1 to 4, wherein the dielectric includes an opening for accommodating a thermocouple.

9. 5. The electrostatic chuck of claim 1, wherein the heater comprises an inner heater having a resistive heating element disposed in the central region and an outer heater having a resistive heating element disposed in the peripheral region.

10. A hollow shaft; a housing coupled to the hollow shaft; and the electrostatic chuck of any one of claims 1 to 4, wherein the dielectric is coupled to the housing and the heater comprises one or more heating elements disposed within the dielectric. Substrate support.

11. The substrate support of claim 10 , wherein the pedestal includes one or more through holes for accommodating lift pins.

12. The substrate support of claim 10 , wherein the pedestal further comprises a cooling plate coupled to a bottom of the pedestal.

13. The substrate support of claim 10 , wherein the one or more heating elements comprise a first resistive heating element disposed in the central region and a second resistive heating element disposed in the peripheral region.

14. The substrate support of claim 10 , wherein the plurality of second openings comprises eight second openings arranged at regular intervals along the peripheral region of the dielectric.

15. a chamber body; a substrate support according to claim 10 disposed within the chamber body; A process chamber comprising:

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