Pressure controlled polishing platen

CROSS-REFERENCE TO RELATED APPLICATIONS:

0001This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/429,422 (Attorney Docket No. 14668L), filed Jan. 3, 2011, which application is hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

00021. Field of the Invention

0003Embodiments of the present invention generally relate to polishing a substrate, such as a semiconductor wafer. More particularly, to modification of forces applied to or acting on a substrate during a polishing process.

00042. Description of the Related Art

0005Chemical mechanical polishing is one process commonly used in the manufacture of high-density integrated circuits to planarize or polish a layer of material deposited on a substrate by moving a feature side, i.e., a deposit receiving surface, of the substrate in contact with a polishing pad while in the presence of a polishing fluid. In a typical polishing process, the substrate is retained in a polishing head that urges or presses the backside of the substrate toward a polishing medium. Material is removed from the feature side of the substrate that is in contact with the polishing medium through a combination of chemical and mechanical activity.

0006Stiffness of the substrate plays an important role in providing the contact necessary to successfully and uniformly remove materials from the feature side of the substrate. Sharp transitions in the pressure applied to the backside of the substrate are sometimes desirable to facilitate uniform material removal. However, stiffness of the substrate tends to redistribute the pressure applied to the substrate such that the pressure applied to the substrate may be spread or smoothed. In some cases, this smoothing effect is undesirable and may cause undesirable polishing results on the substrate.

0007Therefore, there is a need for a method and apparatus that facilitates focused, high resolution control of pressure or force applied to a substrate to facilitate removal of materials from the feature side of the substrate.

SUMMARY OF THE INVENTION

0008A method and apparatus for controlling pressure or forces applied to a substrate in a polishing process is described. In one embodiment, a polishing system is described. The system includes a platen rotatably disposed on a base, the platen having a sidewall and a polishing pad secured to the platen at a perimeter thereof to form an interior volume and a pad pressure applicator disposed in the interior volume of the platen adjacent the underside of the polishing pad.

0009In another embodiment, a method for polishing a substrate is described. The method includes urging a substrate against a first surface of a polishing pad using a first pressure applied from a first pressure applicator to a backside of the substrate, and applying a second pressure to a feature side of the substrate through a second surface of the polishing pad.

0010In another embodiment, a method for polishing a substrate is described. The method includes retaining a substrate in a carrier head adapted to move the substrate relative to a polishing pad, the carrier head having a first pressure applicator that is movable with the substrate, the first pressure applicator having one or more pressure zones that apply pressure to a first side of the substrate, moving the substrate in a sweep pattern relative to a first side of the polishing pad, and delivering a counter pressure to a second side of the substrate from a second pressure applicator as the substrate moves in the sweep pattern, the second pressure applicator disposed on a second side of the polishing pad.

BRIEF DESCRIPTION OF THE DRAWINGS

0011So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

0012<figref idref="DRAWINGS">FIG. 1</figref> is a partial sectional view of one embodiment of a processing station.

0013<figref idref="DRAWINGS">FIG. 2A</figref> is a schematic partial cross-sectional view of another embodiment of a processing station.

0014<figref idref="DRAWINGS">FIG. 2B</figref> is a graphical representation of pressure application to a backside of a substrate.

0015<figref idref="DRAWINGS">FIG. 2C</figref> is a graphical representation of pressure redistribution on a substrate.

0016<figref idref="DRAWINGS">FIG. 3</figref> is a schematic top plan view of one embodiment of a processing station.

0017<figref idref="DRAWINGS">FIG. 4A</figref> is an isometric top view of another embodiment of a processing station having a pad pressure applicator with asymmetric pressure zones.

0018<figref idref="DRAWINGS">FIG. 4B</figref> is an isometric top view of another embodiment of a processing station having a pad pressure applicator with symmetric pressure zones.

0019<figref idref="DRAWINGS">FIG. 4C</figref> is an isometric cross-sectional view of the processing station shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>.

0020<figref idref="DRAWINGS">FIG. 5A</figref> is a schematic cross-sectional view of another embodiment of a pad pressure applicator.

0021<figref idref="DRAWINGS">FIG. 5B</figref> is a schematic cross-sectional view of another embodiment of a pad pressure applicator.

0022<figref idref="DRAWINGS">FIG. 6A</figref> is an isometric top view of another embodiment of a processing station.

0023<figref idref="DRAWINGS">FIG. 6B</figref> is an isometric cross-sectional view of one embodiment of a first pad pressure applicator that may be utilized in the processing station of <figref idref="DRAWINGS">FIG. 6A</figref>.

0024<figref idref="DRAWINGS">FIG. 7A</figref> is an isometric view of one embodiment of an annular plate that may be utilized in the first pad pressure applicator of <figref idref="DRAWINGS">FIG. 6A</figref>.

0025<figref idref="DRAWINGS">FIG. 7B</figref> is an enlarged cross-sectional view of the first pad pressure applicator of <figref idref="DRAWINGS">FIG. 6B</figref>.

0026<figref idref="DRAWINGS">FIG. 7C</figref> is an enlarged cross-sectional view of the rings of <figref idref="DRAWINGS">FIG. 7B</figref>.

0027<figref idref="DRAWINGS">FIG. 8</figref> is schematic plan view of another embodiment of a ring actuation arrangement.

0028<figref idref="DRAWINGS">FIG. 9</figref> is a flowchart showing one embodiment of a method.

0029<figref idref="DRAWINGS">FIG. 10</figref> is a flowchart showing another embodiment of a method.

0030To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

0031<figref idref="DRAWINGS">FIG. 1</figref> is a partial sectional view of one embodiment of a processing station <b>100</b> that is configured to perform a polishing process, such as a chemical mechanical polishing (CMP) process or an electrochemical mechanical polishing (ECMP) process. The processing station <b>100</b> may be a stand-alone unit or part of a larger processing system. Examples of a larger processing system that may be adapted to utilize the processing station <b>100</b> include REFLEXION®, REFLEXION® LK, REFLEXION® GT™, MIRRA MESA® polishing systems available from Applied Materials, Inc., located in Santa Clara, Calif., among other polishing systems.

0032The processing station <b>100</b> includes a platen <b>105</b> rotatably supported on a base <b>110</b>. The platen <b>105</b> is operably coupled to a drive motor <b>115</b> adapted to rotate the platen <b>105</b> about a rotational axis A. The platen <b>105</b> supports a polishing pad <b>120</b> made of a polishing material <b>122</b>. In one embodiment, the polishing material <b>122</b> of the polishing pad <b>120</b> is a commercially available pad material, such as polymer based pad materials typically utilized in CMP processes. The polymer material may be a polyurethane, a polycarbonate, fluoropolymers, polytetrafluoroethylene (PTFE), polyphenylene sulfide (PPS), or combinations thereof. The polishing material <b>122</b> may further comprise open or closed cell foamed polymers, elastomers, felt, impregnated felt, plastics, and like materials compatible with the processing chemistries. In another embodiment, the polishing material <b>122</b> is a felt material impregnated with a porous coating. In other embodiments, the polishing material <b>122</b> includes a material that is at least partially conductive.

0033A carrier head <b>130</b> is disposed above a processing surface <b>125</b> of the polishing pad <b>120</b>. The carrier head <b>130</b> retains a substrate <b>135</b> and controllably urges the substrate <b>135</b> towards the processing surface <b>125</b> (along the Z axis) of the polishing pad <b>120</b> during processing. The platen <b>105</b> contains a pad pressure applicator <b>138</b> (shown in phantom) that applies pressure to an underside of the polishing pad <b>120</b>. The carrier head <b>130</b> is mounted to a support member <b>140</b> that supports the carrier head <b>130</b> and facilitates movement of the carrier head <b>130</b> relative to the polishing pad <b>120</b>. The support member <b>140</b> may be coupled to the base <b>110</b> or mounted above the processing station <b>100</b> in a manner that suspends the carrier head <b>130</b> above the polishing pad <b>120</b>. In one embodiment, the support member <b>140</b> is a circular track that is mounted above the processing station <b>100</b>. The carrier head <b>130</b> is coupled to a drive system <b>145</b> that provides at least rotational movement of the carrier head <b>130</b> about a rotational axis B. The drive system <b>145</b> may additionally be configured to move the carrier head <b>130</b> along the support member <b>140</b> laterally (X and/or Y axes) relative to the polishing pad <b>120</b>. In one embodiment, the drive system <b>145</b> moves the carrier head <b>130</b> vertically (Z axis) relative to the polishing pad <b>120</b> in addition to lateral movement. For example, the drive system <b>145</b> may be utilized to move the substrate <b>135</b> towards the polishing pad <b>120</b> in addition to providing rotational and/or lateral movement of the substrate <b>135</b> relative to the polishing pad <b>120</b>. The lateral movement of the carrier head <b>130</b> may be a linear or an arcing or sweeping motion.

0034A conditioning device <b>150</b> and a fluid applicator <b>155</b> are shown positioned over the processing surface <b>125</b> of the polishing pad <b>120</b>. The conditioning device <b>150</b> is coupled to the base <b>110</b> and includes an actuator <b>185</b> that may be adapted to rotate the conditioning device <b>150</b> or move the conditioning device <b>150</b> in one or more linear directions relative to the polishing pad <b>120</b> and/or the base <b>110</b>. The fluid applicator <b>155</b> includes one or more nozzles <b>160</b> adapted to deliver polishing fluids to a portion of the polishing pad <b>120</b>. The fluid applicator <b>155</b> is rotatably coupled to the base <b>110</b>. In one embodiment, the fluid applicator <b>155</b> is adapted to rotate about a rotational axis C and provides a polishing fluid that is directed toward the processing surface <b>125</b>. The polishing fluid may be a chemical solution, water, a polishing compound, a cleaning solution, or a combination thereof.

0035<figref idref="DRAWINGS">FIG. 2A</figref> is a schematic partial cross-sectional view of another embodiment of a processing station <b>200</b> having a carrier head <b>130</b> and a polishing pad <b>120</b> disposed on a platen <b>105</b> (shown in phantom). The carrier head <b>130</b> is shown having a substrate <b>135</b> disposed therein such that a feature side of the substrate <b>135</b> is in contact with the processing surface <b>125</b> of the polishing pad <b>120</b>. The carrier head <b>130</b> includes a retaining ring <b>205</b> circumscribing and preventing the substrate <b>135</b> from slipping out of the carrier head <b>130</b> during processing. The carrier head <b>130</b> includes a flexible membrane <b>210</b> that contacts the backside of the substrate <b>135</b>. In one embodiment, the carrier head <b>130</b> includes a body <b>215</b> that contains a head pressure applicator <b>220</b> that applies pressure or force to the flexible membrane <b>210</b>. The forces acting on the flexible membrane <b>210</b> are transmitted to the backside of the substrate <b>135</b> to urge zones <b>225</b>A-<b>225</b>B of the feature side of the substrate <b>135</b> toward the processing surface <b>125</b> of the polishing pad <b>120</b>.

0036In one embodiment, head pressure applicator <b>220</b> includes one or more bladders <b>230</b> that are coupled to a fluid supply <b>235</b>. The fluid supply <b>235</b> selectively provides a gas or liquid to each bladder <b>230</b> to apply pressure to the flexible membrane <b>210</b>. The flexible membrane <b>210</b> in turn deflects to apply forces to the backside of the substrate <b>135</b>. The pressure applied to the bladders <b>230</b> may be different and selected in response to factors such as stiffness of the substrate <b>135</b>, desired center-to-edge uniformity or non-uniformity, among other factors. In one embodiment, pressure applied to the bladders <b>230</b> is between about −10 pounds per square inch (psi) to about 90 psi, for example, about −10 psi to about 80 psi.

0037Stiffness of the substrate <b>135</b> tends to redistribute the forces from the flexible membrane <b>210</b>. For example, well defined pressure boundaries between the bladders <b>230</b> may be desired to produce desirable center-to-edge uniformity, as shown in the graph shown in <figref idref="DRAWINGS">FIG. 2B</figref>. As an example, it may be desirable to apply more pressure to the center zone <b>225</b>A of the substrate <b>135</b> and less pressure to edge zone <b>225</b>B of the substrate <b>135</b> (e.g., about 10 mm to about 20 mm inward of a periphery of the substrate <b>135</b>), or vice versa, and have a sharp pressure boundary between these zones. However, the stiffness of the substrate <b>135</b> tends to smooth these desired sharp pressure boundaries, as shown in the graph shown in <figref idref="DRAWINGS">FIG. 2C</figref>. As a result, the smoothing pressure effect is experienced by the feature side of the substrate <b>135</b> such that the center zone <b>225</b>A may be over-polished in order to polish the edge zone <b>225</b>B sufficiently. In an alternative result of the smoothing pressure effect, the edge zone <b>225</b>B may be under-polished in order to polish the center zone <b>225</b>A sufficiently. The smoothed pressure boundaries produce difficulty in controlling polishing uniformity. The smoothed pressure boundaries may negatively affect polishing and may additionally limit tuning of the edge profile of the substrate <b>135</b>.

0038Similar to the embodiment depicted in <figref idref="DRAWINGS">FIG. 1</figref>, the processing station <b>200</b> includes a pad pressure applicator <b>138</b> housed in the platen <b>105</b>. In one embodiment, the pad pressure applicator <b>138</b> includes one or more pressure sources <b>240</b> that deliver a liquid or a gas from a pressure supply <b>260</b> that form a fluid bearing <b>245</b>. The fluid bearing <b>245</b> may be utilized to apply pressure independently to discrete regions of the underside of the polishing pad <b>120</b>. In one example, the pad pressure applicator <b>138</b> includes a lid plate <b>250</b> coupled to a housing <b>255</b> that contains the pressure sources <b>240</b>. The pressure sources <b>240</b> are adapted to provide multiple pressure zones that may be independently controlled to apply a predetermined pressure to each zone defined by the pressure sources <b>240</b>. In one embodiment, the pressure sources <b>240</b> may include bladders, baffles, plenums or chambers formed by walls that separate the pressure sources <b>240</b>. The pressure sources <b>240</b> may form pressure zones that are concentric and/or symmetric or non-concentric and/or non-symmetric. In one embodiment, the pressure sources <b>240</b> are in fluid communication with the pressure supply <b>260</b> that is coupled to a controller. Valves (not shown) are coupled between the pressure supply <b>260</b> and each of the pressure sources <b>240</b> to control fluids and/or pressure applied to the pressure sources <b>240</b>.

0039In one embodiment, the lid plate <b>250</b> comprises a perforated plate having a plurality of nozzles <b>265</b> adapted to direct fluids from the housing <b>255</b> to an underside <b>270</b> of the polishing pad <b>120</b>. Each of the pressure sources <b>240</b> are fluidly coupled to one or more nozzles <b>265</b> to provide the fluid bearing <b>245</b> between the lid plate <b>250</b> and the underside <b>270</b> of the polishing pad <b>120</b>. In this embodiment, the pressure supply <b>260</b> contains a fluid, such as a gas or liquid. In one embodiment, the pressure supply <b>260</b> contains a compressed gas, such as air, nitrogen, helium, argon, derivatives thereof and combinations thereof. In another embodiment, the pressure supply <b>260</b> contains a liquid, such as de-ionized water. The fluid may exit the interior of the platen <b>105</b> through an opening <b>262</b> formed in a wall of the platen <b>105</b>. In one embodiment, the base <b>110</b> may include a drain port <b>264</b> adapted to receive the fluid as it exits the platen <b>105</b>.

0040Each of the pressure sources <b>240</b> may be independently controlled to provide pressurized fluids to the underside <b>270</b> of the polishing pad <b>120</b>. In some embodiments, the platen <b>105</b> may include a flexible backing <b>275</b> between the underside <b>270</b> of the polishing pad <b>120</b>. The flexible backing <b>275</b> may be a flexible plate or membrane adapted to cover the platen <b>105</b> and prevent polishing fluids from entering an interior volume <b>278</b> of the platen <b>105</b>. In one embodiment, the flexible backing <b>275</b> is a fabric/plastic composite material with a low coefficient of friction and includes a thickness of about 10 mils to about 20 mils. In one aspect, the flexible backing <b>275</b> comprises a PEEK material reinforced by a KEVLAR® fabric. The flexible backing <b>275</b> is utilized to prevent liquids and polishing debris from entering the interior volume <b>278</b> of the platen <b>105</b>. Additionally the flexible backing <b>275</b> may also be used to control pressure application to the underside <b>270</b> of the polishing pad <b>120</b>. In one embodiment, the flexible backing <b>275</b> is coupled to a perimeter of the platen <b>105</b> by a plurality of clamps or tensioner devices <b>280</b> that are adapted to stretch the flexible backing <b>275</b> and facilitate tautness of the flexible backing <b>275</b> on the platen <b>105</b>. One or more of the tensioner devices <b>280</b> may be configured as a releasable clamp having a turnbuckle, spring or other tension applying member coupled thereto.

0041In one embodiment, the pad pressure applicator <b>138</b> is coupled to the base <b>110</b> such that the pad pressure applicator <b>138</b> is stationary relative to the base <b>110</b>. In another embodiment, the pad pressure applicator <b>138</b> is movable relative to the base <b>110</b>. In one embodiment, the housing <b>255</b> of the pad pressure applicator <b>138</b> is coupled to an actuator <b>285</b> that is adapted to move the housing <b>255</b> relative to the base <b>110</b>. The actuator <b>285</b> is adapted to move the pad pressure applicator <b>138</b> in at least a lateral direction (i.e., horizontally) relative to the base <b>110</b> so the pad pressure applicator <b>138</b> may move in the same direction as the substrate <b>135</b> retained in the carrier head <b>130</b>. In another embodiment, the actuator <b>285</b> may be configured to move the pad pressure applicator <b>138</b> toward and away (i.e., vertically) from the underside <b>270</b> of the polishing pad <b>120</b>.

0042In one embodiment, the pressure of the fluid applied to the underside <b>270</b> of the polishing pad <b>120</b> is about −10 psi to about 10 psi. The pressure may be constant or intermittent within or between the pressure sources <b>240</b>. In one embodiment, the carrier head <b>130</b> is configured to move the substrate <b>135</b> laterally in a sweep pattern across the processing surface <b>125</b> of the polishing pad <b>120</b>. In this embodiment, the pressure applied to the underside <b>270</b> of the polishing pad <b>120</b> may be varied in response to the position of the substrate <b>135</b> relative to the pad pressure applicator <b>138</b>. In another embodiment, the pad pressure applicator <b>138</b> is configured to move with the substrate <b>135</b> in the sweep pattern. In this embodiment, the pressure applied to the underside <b>270</b> of the polishing pad <b>120</b> may be varied or constant as the substrate <b>135</b> and the pad pressure applicator <b>138</b> move in the sweep pattern.

0043<figref idref="DRAWINGS">FIG. 3</figref> is a schematic top plan view of one embodiment of a processing station <b>300</b> showing an embodiment of a polishing sweep pattern <b>305</b> of a substrate <b>135</b> on a polishing pad <b>120</b>. The substrate <b>135</b> is retained in a carrier head <b>130</b> (<figref idref="DRAWINGS">FIG. 1</figref>) that is not shown for clarity. The carrier head moves the substrate <b>135</b> linearly or in an arc across the processing surface <b>125</b> while rotating the substrate <b>135</b> relative to the rotating polishing pad <b>120</b> to effect removal of material from the substrate <b>135</b>. A conditioning device <b>150</b> having a conditioning disk <b>310</b> is also shown to illustrate one embodiment of a conditioning sweep pattern <b>315</b> on the polishing pad <b>120</b>. The conditioning disk <b>310</b> is swept across the processing surface <b>125</b> to condition and/or refresh the processing surface <b>125</b> to facilitate an enhanced removal rate of material from the substrate <b>135</b>.

0044The processing station <b>300</b> includes a first pad pressure applicator <b>325</b>A shown in phantom below the polishing pad <b>120</b>. The first pad pressure applicator <b>325</b>A may be configured similarly to the pad pressure applicator <b>138</b> as described herein. In one embodiment, the first pad pressure applicator <b>325</b>A includes a dimension defining an area that is greater than the area of the substrate <b>135</b>. The area of the first pad pressure applicator <b>325</b>A may also be sized greater than the sweep pattern <b>305</b> of the substrate on the polishing pad. In one aspect, the shape of the first pad pressure applicator <b>325</b>A is substantially elliptical in plan view having a major diameter or axis substantially aligned with the length or greater axis of the polishing sweep pattern <b>305</b>. In one embodiment, the shape of the first pad pressure applicator <b>325</b>A in plan view comprises a minor diameter or minor axis that is greater than a diameter of the substrate <b>135</b> and a major diameter or major axis that is at least 2 times greater than the substrate <b>135</b>. For example, the minor diameter or axis is about 310 mm to about 380 mm and the major diameter or axis is about 310 mm to about 760 mm for a 300 mm substrate.

0045In one embodiment, the processing station <b>300</b> also includes a second pad pressure applicator <b>325</b>B shown in phantom below the polishing pad <b>120</b> adjacent the conditioning disk <b>310</b>. The second pad pressure applicator <b>325</b>B may be configured similarly to the pad pressure applicator <b>138</b> as described herein and is configured to apply pressure to the underside of the polishing pad <b>120</b> where the conditioning disk <b>310</b> is moved across the processing surface <b>125</b>. The second pad pressure applicator <b>325</b>B may also include dimensions defining an area greater than a dimension of the conditioning disk <b>310</b>. The area of the second pad pressure applicator <b>325</b>B may also be sized greater than the conditioning sweep pattern <b>315</b>.

0046<figref idref="DRAWINGS">FIG. 4A</figref> is an isometric top view of another embodiment of a processing station <b>400</b>. The processing station <b>400</b> includes a platen <b>105</b> rotatably disposed on a base <b>110</b>. A carrier head and polishing pad is not shown on the platen <b>105</b> to illustrate details of one embodiment of a first pad pressure applicator <b>325</b>A and a second pad pressure applicator <b>325</b>B that are housed within an interior volume <b>405</b> defined by a sidewall <b>409</b> of the platen <b>105</b> and the underside <b>270</b> of the polishing pad <b>120</b> (not shown). In one embodiment, the first pad pressure applicator <b>325</b>A and the second pad pressure applicator <b>325</b>B are coupled to a stationary base <b>407</b>. The stationary base <b>407</b> is coupled to the base <b>110</b> through an opening <b>415</b> in a bottom of the platen <b>105</b>. The stationary base <b>407</b> allows the first pad pressure applicator <b>325</b>A and second pad pressure applicator <b>325</b>B to be rigidly coupled to the base <b>110</b> while allowing rotation of the platen <b>105</b> relative to the first pad pressure applicator <b>325</b>A and second pad pressure applicator <b>325</b>B.

0047The first pad pressure applicator <b>325</b>A includes a lid plate <b>250</b> disposed on a housing <b>255</b>. The housing <b>255</b> contains one or more pressure zones shown in phantom as center pressure zone <b>440</b>A and one or more edge pressure zones <b>440</b>B-<b>440</b>E. Each of the pressure zones <b>440</b>A-<b>440</b>E may be formed by the pressure sources <b>240</b> described in <figref idref="DRAWINGS">FIG. 2A</figref>. In one embodiment, a first pressure is applied to the backside of a substrate by the carrier head <b>130</b> (<figref idref="DRAWINGS">FIG. 2A</figref>) and the first pad pressure applicator <b>325</b>A applies a second pressure to the feature side of the substrate through the polishing pad <b>120</b>. In one aspect, each of the pressure zones <b>440</b>A-<b>440</b>E may be configured to provide a sub-pressure to the underside of the polishing pad. In one embodiment, the center pressure zone <b>440</b>A may be configured to provide a first sub-pressure to the underside of the polishing pad and the one or more edge pressure zones <b>440</b>B-<b>440</b>E may be configured to provide a second sub-pressure to the underside of the polishing pad. The first sub-pressure may be the same as or different from the second sub-pressure. In one embodiment, the first sub-pressure is greater than the second sub-pressure in order to apply more pressure to a center of a substrate than the periphery of the substrate, or vice-versa.

0048In this embodiment, the pressure zones <b>440</b>A-<b>440</b>E are asymmetric such that the pressures applied to the underside of the polishing pad are different and create transition regions adjacent the areas in contact with or in fluid communication with the pressure zones <b>440</b>A-<b>440</b>E. In one example, the transition regions are adjacent boundaries of the pressure zones <b>440</b>A-<b>440</b>E. In one embodiment, the first pad pressure applicator <b>325</b>A includes non-pressurized areas <b>410</b>. In one embodiment, the non-pressurized areas <b>410</b> comprise regions of the lid plate <b>250</b> that are not in contact or in fluid communication with a pressure zone <b>440</b>A-<b>440</b>E. The non-pressurized areas <b>410</b> may be utilized to counter polishing effects that may result in over-polishing of the substrate <b>135</b>. In one example, the non-pressurized areas <b>410</b> may be utilized to prevent or minimize over-polishing of the substrate <b>135</b> that may occur as the trailing edge of the rotating substrate <b>135</b> is over the first pad pressure applicator <b>325</b>A. In another embodiment, non-pressurized areas <b>410</b> are reduced or eliminated and pressure in one or more of the pressure zones <b>440</b>A-<b>440</b>E is reduced to counteract over-polishing of the substrate <b>135</b>. In one embodiment, the pressure in one or more of the pressure zones <b>440</b>A-<b>440</b>E may be reduced to vacuum (i.e., about −10 psi) to counteract over-polishing of the substrate <b>135</b>.

0049In one embodiment, second pad pressure applicator <b>325</b>B includes a lid plate <b>417</b> and a housing <b>420</b> that is similar to the pad pressure applicator <b>138</b> described in <figref idref="DRAWINGS">FIG. 2A</figref>. The housing <b>420</b> may contain a pressure zone <b>430</b> that is formed by a pressure source <b>240</b> that is described in <figref idref="DRAWINGS">FIG. 2A</figref>. While only one pressure zone <b>430</b> is shown, additional pressure zones may be utilized. The pressure zone <b>430</b> is adapted to apply pressure to the underside of the polishing pad where the conditioning disk <b>310</b> is swept across the polishing pad. The lid plate <b>417</b> may be similar to the lid plate <b>250</b> and may be perforated, adapted to contact the underside of the polishing pad, and combinations thereof to apply pressure to the underside of the polishing pad.

0050<figref idref="DRAWINGS">FIG. 4B</figref> is an isometric top view of another embodiment of a processing station <b>400</b> which is similar to the embodiment shown in <figref idref="DRAWINGS">FIG. 4A</figref> with the exception of symmetric or concentric pressure zones <b>440</b>A-<b>440</b>E in the first pad pressure applicator <b>325</b>A. In this embodiment, non-pressurized areas <b>410</b> (<figref idref="DRAWINGS">FIG. 4A</figref>) are eliminated and pressure in one or more of the pressure zones <b>440</b>A-<b>440</b>E may be reduced to counteract over-polishing of the substrate <b>135</b>.

0051<figref idref="DRAWINGS">FIG. 4C</figref> is an isometric cross-sectional view of the processing station <b>400</b> shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. The second pad pressure applicator <b>325</b>B is not shown in this view so details of the interface between the base <b>110</b> and the platen <b>105</b> can be seen. In one aspect, the polishing pad <b>120</b> is circular or ring-shaped. A perimeter of the polishing pad <b>120</b> is coupled to the platen <b>105</b> to bound one side of the interior volume <b>405</b>. In one embodiment, the platen <b>105</b> is coupled to the motor <b>115</b> by a gear mechanism <b>450</b>. The first pad pressure applicator <b>325</b>A is coupled to the base <b>110</b> through the opening <b>415</b> and is offset from the gear mechanism <b>450</b> in a manner that does not interfere with rotation of the gear mechanism <b>450</b> and/or the platen <b>105</b>. In another embodiment, the first pad pressure applicator <b>325</b>A may be movably coupled to the base <b>110</b> by an actuator (such as actuator <b>285</b> shown in <figref idref="DRAWINGS">FIG. 2A</figref>).

0052<figref idref="DRAWINGS">FIG. 5A</figref> is a schematic cross-sectional view of another embodiment of a pad pressure applicator <b>500</b> that may be utilized in the processing station <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> or either of the first pad pressure applicator <b>325</b>A and second pad pressure applicator <b>325</b>B of <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. In this embodiment, the pad pressure applicator <b>500</b> includes a bearing surface <b>505</b> comprising a plurality of contact bearings <b>510</b> adapted to contact the underside <b>270</b> of the polishing pad <b>120</b>. Each of the contact bearings <b>510</b> may comprise protrusions extending from the bearing surface <b>505</b>, roller elements protruding from the bearing surface <b>505</b>, and combinations thereof. In one embodiment, the contact bearings <b>510</b> are protrusions or raised areas of the bearing surface <b>505</b> and are made from or include a material having a low coefficient of friction. In one embodiment, the contact bearings <b>510</b> comprise roller elements at least partially contained in pockets <b>515</b> disposed in a lid plate <b>250</b> of the pad pressure applicator <b>500</b>. Each of the roller elements are made from or include a material having a low coefficient of friction.

0053In one embodiment, a housing <b>255</b> of the pad pressure applicator <b>500</b> includes one or more bladders <b>520</b> that are coupled to a pressure supply <b>260</b> adapted to apply force to the bearing surface <b>505</b> and/or the contact bearings <b>510</b>. Pressure delivered to each of the bladders <b>520</b> may be independently controlled to provide a controlled force to the contact bearings <b>510</b> and to the underside <b>270</b> of the polishing pad <b>120</b>. In one embodiment, the pressure of the fluid applied to the bladders <b>520</b> is about −10 psi to about 10 psi.

0054<figref idref="DRAWINGS">FIG. 5B</figref> is a schematic cross-sectional view of another embodiment of a pad pressure applicator <b>525</b> that may be utilized in the processing station <b>100</b> of <figref idref="DRAWINGS">FIG. 1</figref> or either of the first pad pressure applicator <b>325</b>A and second pad pressure applicator <b>325</b>B of <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>. In this embodiment, the pad pressure applicator <b>500</b> includes a contact surface <b>530</b> adapted to contact a portion of the underside <b>270</b> of the polishing pad <b>120</b>. The contact surface <b>530</b> comprises a flexible membrane <b>535</b> disposed in the housing <b>255</b> of pad pressure applicator <b>525</b>. The flexible membrane <b>535</b> may be disposed on the lid plate <b>250</b> (not shown) of pad pressure applicator <b>500</b> or replace the lid plate <b>250</b>. The flexible membrane <b>535</b> is adapted to contact the underside <b>270</b> of the polishing pad <b>120</b>. The flexible membrane <b>535</b> may be made of a material having a low coefficient of friction, such as fluoropolymers, polytetrafluoroethylene (PTFE), high density polyethylene (HDPE), ultra-high molecular weight (UHMW) plastics, polyphenylene sulfide (PPS), or combinations thereof.

0055In one embodiment, a housing <b>255</b> of the pad pressure applicator <b>500</b> includes one or more chambers <b>540</b> that are coupled to a pressure supply <b>260</b> adapted to apply force to flexible membrane <b>535</b>. Pressure delivered to each of the chambers <b>540</b> may be independently controlled to provide a controlled force to the flexible membrane <b>535</b> and to the underside <b>270</b> of the polishing pad <b>120</b>. In one embodiment, the pressure of the fluid applied to the chambers <b>540</b> is about −10 psi to about 10 psi.

0056<figref idref="DRAWINGS">FIG. 6A</figref> is an isometric top view of another embodiment of a processing station <b>600</b> having another embodiment of a first pad pressure applicator <b>625</b>A. Elements of the processing station <b>600</b> which are similar to the embodiment of the processing station <b>400</b> shown in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref> will not be repeated for brevity. In this embodiment, the first pad pressure applicator <b>625</b>A includes a plurality of rings <b>605</b>, <b>610</b> and <b>615</b> movably disposed within the lid plate <b>250</b> and interspersed within one or more pressure zones <b>440</b>A-<b>440</b>C. In one embodiment, one or more of the plurality of rings <b>605</b>, <b>610</b> and <b>615</b> are semi-flexible rings that are independently movable within the lid plate <b>250</b> of the first pad pressure applicator <b>625</b>A.

0057<figref idref="DRAWINGS">FIG. 6B</figref> is an isometric cross-sectional view of one embodiment of a first pad pressure applicator <b>625</b>A that may be utilized in the processing station <b>600</b> of <figref idref="DRAWINGS">FIG. 6A</figref>. In this embodiment, the first pad pressure applicator <b>625</b>A includes an inner pressure zone <b>620</b>A, an intermediate pressure zone <b>620</b>B, a first outer pressure zone <b>620</b>C and a second outer pressure zone <b>620</b>D. Each of the inner pressure zone <b>620</b>A, the intermediate pressure zone <b>620</b>B, the first outer pressure zone <b>620</b>C and the second outer pressure zone <b>620</b>D are coupled to one or more pressurized fluid sources that are independently controlled by a controller.

0058In one embodiment, the inner pressure zone <b>620</b>A comprises a dual zone air bearing having a sub-inner zone <b>626</b>A and a sub-outer zone <b>626</b>B that are independently controlled. The sub-inner zone <b>626</b>A includes a first plenum <b>630</b>A that is coupled to a pressure supply <b>260</b> by a conduit <b>635</b>A while the sub-outer zone <b>626</b>B is coupled to the pressure supply <b>260</b> by one or more conduits <b>635</b>B. In one embodiment, the first plenum <b>630</b>A is in communication with a plurality of openings <b>632</b> while the sub-outer zone <b>626</b>B comprises a channel <b>634</b>. Pressurized fluid is flowed from the pressure supply <b>260</b> to the channel <b>634</b> and/or the first plenum <b>630</b>A where pressurized fluid is released the lid plate <b>250</b> through the openings <b>632</b> and channel <b>634</b>.

0059The intermediate pressure zone <b>620</b>B comprises a second plenum <b>630</b>B that is coupled to the pressure supply <b>260</b> by a conduit <b>635</b>C. The second outer pressure zone <b>620</b>D comprises a third plenum <b>630</b>C that is coupled to the pressure supply <b>260</b> by a conduit <b>635</b>D. Fluids from the pressure supply <b>260</b> are flowed to the plenums <b>630</b>B and <b>630</b>C and through the openings <b>632</b> in the lid plate <b>250</b>. In one embodiment, the inner pressure zone <b>620</b>A and intermediate pressure zone <b>620</b>B provide a counter pressure to a center zone <b>225</b>A (<figref idref="DRAWINGS">FIG. 2A</figref>) of a substrate while the first outer pressure zone <b>620</b>C provides a counter pressure to a peripheral zone <b>225</b>B (<figref idref="DRAWINGS">FIG. 2A</figref>) of the substrate. In one aspect, the first outer pressure zone <b>620</b>C is positioned at the periphery of a substrate while the second outer pressure zone <b>620</b>D is sized and positioned to provide a counter pressure to a retaining ring <b>205</b> of a carrier head <b>130</b> (both shown in <figref idref="DRAWINGS">FIG. 2A</figref>).

0060In this embodiment, the first outer pressure zone <b>620</b>C comprises one or more rings <b>605</b>, <b>610</b> and <b>615</b>. In one embodiment, the first outer pressure zone <b>620</b>C is positioned on the lid plate <b>250</b> to correspond with the periphery of the substrate. In one aspect, the diameter of the first outer pressure zone <b>620</b>C is about 280 mm to about 320 mm, such as about 290 mm to about 310 mm. In one embodiment, one of the rings <b>605</b>-<b>615</b> comprises a diameter of about 300 mm while the other rings are concentric and include a diameter that may be slightly greater or less than 300 mm. Each of the rings <b>605</b>, <b>610</b> and <b>615</b> are coupled to one or more actuators <b>640</b> that are independently controlled. In one embodiment, each of the actuators <b>640</b> include a piston <b>645</b> that is adapted to selectively raise and lower relative to a base <b>650</b> of the first pad pressure applicator <b>625</b>A.

0061<figref idref="DRAWINGS">FIG. 7A</figref> is an isometric view of one embodiment of an annular plate <b>655</b> that may be utilized in the first pad pressure applicator <b>625</b>A of <figref idref="DRAWINGS">FIG. 6A</figref>. The annular plate <b>655</b> includes a rigid portion <b>660</b>A on an inner diameter that couples to the base <b>650</b> of the first pad pressure applicator <b>625</b>A. The rigid portion <b>660</b>A includes holes <b>700</b> for mounting to the base <b>650</b> of the first pad pressure applicator <b>625</b>A. The annular plate <b>655</b> also includes a flexible portion <b>660</b>B on an outer diameter of the annular plate <b>655</b>. A slot <b>705</b> is formed in the annular plate <b>655</b> to at least partially separate the rigid portion <b>660</b>A from the flexible portion <b>660</b>B and allow the connecting material <b>710</b> to form a live spring. The annular plate <b>655</b> may be fabricated from plastic materials or metallic materials, such as stainless steel.

0062<figref idref="DRAWINGS">FIG. 7B</figref> is an enlarged cross-sectional view of the first pad pressure applicator <b>625</b>A of <figref idref="DRAWINGS">FIG. 6B</figref>. The piston <b>645</b> is adapted to contact the flexible portion <b>660</b>B of the annular plate <b>655</b>. The flexible portion <b>660</b>B is adapted to bend upon pressure from the piston <b>645</b> and contact a leg <b>665</b>A-<b>665</b>C coupled to each of the rings <b>605</b>-<b>615</b>.

0063<figref idref="DRAWINGS">FIG. 7C</figref> is an enlarged cross-sectional view of the rings <b>605</b>-<b>615</b> of <figref idref="DRAWINGS">FIG. 7B</figref>. In one embodiment of a ring actuation arrangement, each ring <b>605</b>-<b>615</b> includes a leg <b>665</b>A-<b>665</b>C that is adapted to engage a desired area of a flexible portion <b>660</b>B of the annular plate <b>655</b>. Each leg <b>665</b>A-<b>665</b>C is positioned relative to the flexible portion <b>660</b>B such that engagement of the flexible portion <b>660</b>B contacts a specific leg <b>665</b>A, <b>665</b>B or <b>665</b>C without contact with another leg, which allows the rings <b>605</b>-<b>615</b> to be individually actuated. In one aspect, each leg <b>665</b>A-<b>665</b>C is shaped and/or staggered to be spaced apart from another leg to prevent more than one leg being contacted by the flexible portion <b>660</b>B when actuated. Each leg <b>665</b>A-<b>665</b>C may be fabricated from a rigid metallic material or plastic material.

0064Each of the rings <b>605</b>-<b>615</b> includes an annular channel <b>670</b> supporting a compressible member <b>675</b>. The annular channel <b>670</b> may be fabricated from rigid plastics or metals. The annular channel <b>670</b> includes a structure and/or thickness that provides a stiff or rigid backing for the compressible member <b>675</b>. In one embodiment, the annular channel <b>670</b> is fabricated from a stainless steel material. The compressible member <b>675</b> is adapted to contact the underside of the polishing pad (not shown) and is sized and shaped to prevent contact between the polishing pad and the annular channel <b>670</b>. In one embodiment, the annular channel includes a C or U shaped cross-section while the compressible member <b>675</b> includes a T shaped cross-section as shown. The compressible member <b>675</b> may be made from compressible materials having a low coefficient of friction, such as PEEK. The PEEK material may also include other materials, such as carbon fibers, to form a composite material.

0065<figref idref="DRAWINGS">FIG. 8</figref> is schematic plan view of another embodiment of a ring actuation arrangement <b>800</b>. In this embodiment, the position of pistons <b>810</b>A-<b>810</b>C are shown schematically relative to the rings <b>605</b>-<b>615</b>. Each of the pistons <b>810</b>A-<b>810</b>C are schematic representations of the piston <b>645</b> coupled to the actuator <b>640</b> of <figref idref="DRAWINGS">FIGS. 6B and 6C</figref>. In one aspect, each ring <b>605</b>-<b>615</b> is aligned with three pistons that are spaced at substantially equal intervals along the ring. For example, ring <b>605</b> is aligned with pistons <b>810</b>C, ring <b>610</b> is aligned with pistons <b>810</b>B and ring <b>615</b> is aligned with pistons <b>810</b>A. Each of the pistons <b>810</b>A-<b>810</b>C is independently actuatable to provide pressure to at least a portion of each ring independent of other rings or pistons. In one embodiment, each ring <b>605</b>-<b>615</b> is independently actuatable by three actuators. In one embodiment, each of the three actuators is spaced at about <b>120</b> degree intervals relative to one ring and/or a radius of one ring. In another embodiment, each of the actuators are spaced concentrically and spaced-apart angularly by about 40 degrees. In this embodiment, the annular plate <b>655</b> as described in <figref idref="DRAWINGS">FIGS. 6B and 6C</figref> may be utilized between each of the rings <b>605</b>-<b>615</b> and the pistons <b>810</b>A-<b>810</b>C.

0066<figref idref="DRAWINGS">FIG. 9</figref> is a flowchart showing one embodiment of a method <b>900</b>. At step <b>910</b>, a substrate <b>135</b> is urged against a first surface (e.g., processing surface <b>125</b>) of a polishing pad <b>120</b>. In one embodiment, at least a first pressure from a first pressure applicator (e.g., head pressure applicator <b>220</b>) which is in communication with a backside of the substrate is utilized to urge the substrate <b>135</b> against the first surface. In one example, pressure is delivered to one or more bladders <b>230</b> disposed in the first pressure applicator to provide pressure to the backside of the substrate <b>135</b>. The bladders <b>230</b> may provide a first pressure to a center zone <b>225</b>A of the substrate <b>135</b> independently of a second pressure to an edge zone <b>225</b>B of the substrate <b>135</b>. The first pressure and second pressure may be the same or different. In one embodiment, the first pressure and second pressure applied to the bladders <b>230</b> is about −10 psi to about 80 psi.

0067At step <b>920</b>, a second pressure is delivered to a feature side of the substrate <b>135</b>. The second pressure is delivered through a second surface of the polishing pad from a second pressure applicator (e.g., pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A) disposed on an opposing side of the polishing pad <b>120</b> relative to the substrate <b>135</b>. The second pressure may be substantially equal to or different than the first pressure. In one embodiment, the second pressure applicator includes a center pressure zone <b>440</b>A and one or more edge pressure zones <b>440</b>B-<b>440</b>E. The center pressure zone <b>440</b>A and one or more edge pressure zones <b>440</b>B-<b>440</b>E may comprise pressure sources <b>240</b> that comprise bladders or discrete chambers formed in the second pressure applicator. In one embodiment, the pressure delivered to each pressure source <b>240</b> includes at least a third pressure and a fourth pressure to the center pressure zone <b>440</b>A and one or more edge pressure zones <b>440</b>B-<b>440</b>E, respectively. The third pressure and fourth pressure may be the same or different. In one embodiment, the third pressure and fourth pressure applied to the pressure sources <b>240</b> may be about −10 psi to about 10 psi. In another embodiment, the second pressure is provided by one or more rings <b>605</b>, <b>610</b> and <b>615</b> in addition to one or more pressure zones <b>620</b>A-<b>620</b>D as described in <figref idref="DRAWINGS">FIG. 6A-6C</figref>.

0068<figref idref="DRAWINGS">FIG. 10</figref> is a flowchart showing another embodiment of a method <b>1000</b>. At step <b>1010</b>, a substrate <b>135</b> is retained in a carrier head <b>130</b> adapted to move the substrate <b>135</b> relative to a polishing pad <b>120</b>. The carrier head <b>130</b> includes a first pressure applicator (e.g., head pressure applicator <b>220</b>) that is movable with the substrate. In one embodiment, the first pressure applicator includes one or more pressurizable zones (e.g., bladders <b>230</b>) that apply a pressure to a first side (e.g., backside) of the substrate <b>135</b>. In one embodiment, the pressure applied to the first side of the substrate is about −10 psi to about 80 psi.

0069At step <b>1020</b>, the substrate <b>135</b> is moved relative to a first side of the polishing pad <b>120</b> (e.g., processing surface <b>125</b>), for example, in a sweep pattern <b>305</b>. At step <b>1030</b>, a counter pressure is delivered to a second side (e.g., feature side) of the substrate <b>135</b>. The counter pressure is provided from a second pressure applicator disposed on a second side (e.g., underside <b>270</b>) of the polishing pad <b>120</b> (e.g., pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A) as the substrate moves in the sweep pattern. Thus, the first pressure acting on the first side of the substrate <b>135</b> may be countered by the second pressure as the substrate <b>135</b> travels across the polishing pad <b>120</b>. In one embodiment, the second pressure applicator is stationary relative to the polishing pad <b>120</b>. In another embodiment, the second pressure applicator is movable relative to the polishing pad <b>120</b>. The counter pressure may be substantially equal to or different than the first pressure. In one embodiment, the counter pressure may be about −10 psi to about 10 psi. The counter pressure may be in the form of a static force or an air bearing.

0070A method and apparatus for controlling pressure or forces applied to a substrate in a polishing process is described. The method and apparatus described herein facilitates focused, high resolution control of pressure or force applied to a substrate, which facilitates enhanced removal of material from a substrate. The apparatus includes embodiments of a pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A as described herein. The pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A is utilized to control pressure boundaries the substrate may experience in a polishing process. Thus, improved control of pressures or forces acting on the substrate facilitates greater polishing uniformity, enhanced removal rate, as well as enhancing profile tuning. The pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A is adapted to apply a pressure between about −10 psi to about 10 psi as the substrate travels in a sweep pattern. In this manner, the substrate experiences a desired counter pressure along the entirety of the sweep pattern. Additionally, a second pad pressure applicator <b>325</b>B is described for a conditioning device. The second pad pressure applicator <b>325</b>B may be constructed and operated in a manner similar to the pad pressure applicator <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A. The counter pressure provided to the polishing pad <b>120</b> from the pad pressure applicators <b>138</b>, <b>325</b>A, <b>500</b>, <b>525</b> or <b>625</b>A may be controlled independently from the pressure applied to the polishing pad <b>120</b> from the second pad pressure applicator <b>325</b>B.

0071While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.