Method and apparatus for electromechanically and/or electrochemically-mechanically removing conductive material from a microelectronic substrate

TECHNICAL FIELD

0001This invention relates to a method and an apparatus for electromechanically and/or electrochemically-mechanically removing conductive material from microelectronic substrates.

BACKGROUND

0002Microelectronic substrates and substrate assemblies typically include a semiconductor material having features, such as memory cells, that are linked with conductive lines. The conductive lines can be formed by first forming trenches or other recesses in the semiconductor material, and then overlaying a conductive material (such as a metal) in the trenches. The conductive material is then selectively removed to leave conductive lines extending from one feature in the semiconductor material to another. In <patcit id="pcit0001" dnum="US2002025760A1"><text>US 2002/025760 A1</text></patcit> there are disclosed methods and an apparatus for electrically and/or chemically-mechanically removing conductive material from a microelectronic substrate. An apparatus therefore can include a support member that supports the substrate, and the material removal medium can include a polishing pad having a first portion adjacent to a first electrode and a second portion adjacent to a second electrode. A fluid can be disposed between the microelectronic substrate and a polishing surface of polishing pad to facilitate electrical and/or chemical-mechanical removal of the conductive material. The electrodes are coupled to a source of varying electrical signals. According to an embodiment, the electrodes are separated from each other by a gap. Moreover, an exposed surface of each of the electrodes directly faces the substrate, wherein these exposed surfaces can include channels defined by channel surfaces that can collect gas bubbles and conduct the gas bubbles away from the region proximate to the substrate and/or the electrodes.

0003Electrolytic techniques have been used to both deposit and remove metallic layers from semiconductor substrates. For example, an alternating current can be applied to a conductive layer via an intermediate electrolyte to remove portions of the layer. In one arrangement, shown in Figure 1, a conventional apparatus 60 includes a first electrode 20a and a second electrode 20b coupled to a current source 21. The first electrode 20a is attached directly to a metallic layer 11 of a semiconductor substrate 10 and the second electrode 20b is at least partially immersed in a liquid electrolyte 31 disposed on the surface of the metallic layer 11 by moving the second electrode downwardly until it contacts the electrolyte 31. A barrier 22 protects the first electrode 20a from direct contact with the electrolyte 31. The current source 21 applies alternating current to the substrate 10 via the electrodes 20a and 20b and the electrolyte 31 to remove conductive material from the conductive layer 11. The alternating current signal can have a variety of wave forms, such as those disclosed by Frankenthal et al. in a publication entitled, "Electroetching of Platinum in the Titanium-Platinum-Gold Metallization on Silicon Integrated Circuits" (Bell Laboratories).

0004One drawback with the arrangement shown in Figure 1 is that it may not be possible to remove material from the conductive layer 11 in the region where the first electrode 20a is attached because the barrier 22 prevents the electrolyte 31 from contacting the substrate 10 in this region. Alternatively, if the first electrode 20a contacts the electrolyte in this region, the electrolytic process can degrade the first electrode 20a. Still a further drawback is that the electrolytic process may not uniformly remove material from the substrate 10. For example, "islands" of residual conductive material having no direct electrical connection to the first electrode 20a may develop in the conductive layer 11. The residual conductive material can interfere with the formation and/or operation of the conductive lines, and it may be difficult or impossible to remove with the electrolytic process unless the first electrode 20a is repositioned to be coupled to such "islands."

0005One approach to addressing some of the foregoing drawbacks is to attach a plurality of first electrodes 20a around the periphery of the substrate 10 to increase the uniformity with which the conductive material is removed. However, islands of conductive material may still remain despite the additional first electrodes 20a. Another approach is to form the electrodes 20a and 20b from an inert material, such as carbon, and remove the barrier 22 to increase the area of the conductive layer 11 in contact with the electrolyte 31. However, such inert electrodes may not be as effective as more reactive electrodes at removing the conductive material, and the inert electrodes may still leave residual conductive material on the substrate 10.

0006Figure 2 shows still another approach to addressing some of the foregoing drawbacks in which two substrates 10 are partially immersed in a vessel 30 containing the electrolyte 31. The first electrode 20a is attached to one substrate 10 and the second electrode 20b is attached to the other substrate 10. An advantage of this approach is that the electrodes 20a and 20b do not contact the electrolyte. However, islands of conductive material may still remain after the electrolytic process is complete, and it may be difficult to remove conductive material from the points at which the electrodes 20a and 20b are attached to the substrates 10.

SUMMARY

0007The present invention is directed toward an apparatus according to claim 1 and a method according to claim 15.

0008Particularly, the present invention is concerned with a method and an apparatus for electromechanically and/or electrochemically-mechanically removing conductive material from a microelectronic substrate. An apparatus in accordance with one aspect of the invention particularly includes a support member configured to releasably carry a microelectronic substrate. First and second electrodes are positioned to be spaced apart from each other and from the microelectronic substrate when the microelectronic substrate is carried by the support member. At least one of the electrodes is coupleable to a source of varying electrical signals. A polishing medium, at least a portion of which is positioned between the electrodes and the support member, includes a polishing surface positioned to contact the microelectronic substrate when the microelectronic substrate, is carried, by the support member. At least a portion of the first and second electrodes is recessed from the polishing surface.

0009The polishing medium has a plurality of flow passages coupleable to a source of liquid and each flow passage has an aperture proximate to the polishing surface further the polishing medium includes a recess proximate to each aperture, the recess being offset from the polishing surface.

0010A method in accordance with another aspect of the invention particularly includes contacting the microelectronic substrate with a polishing surface of a polishing medium, positioning the microelectronic substrate proximate to and spaced apart from first and second electrodes, which are in turn spaced apart from each other and recessed from the polishing surface. The method further includes moving the microelectronic substrate relative to the first and second electrodes while passing a variable electrical signal through the electrodes and the microelectronic substrate.

0011An electrolytic liquid is directed through a plurality of flow passages in the polishing medium, and out of the flow passages to an area of the polishing medium that is recessed from the polishing surface.

BRIEF DESCRIPTION OF THE DRAWINGS

0012<ul id="ul0001" list-style="none"><li>Figure 1 is a partially schematic, side elevational view of an apparatus for removing conductive material from a semiconductor substrate in accordance with the prior art.</li><li>Figure 2 is a partially schematic side, elevational view of another apparatus for removing conductive material from two semiconductor substrates in accordance with the prior art.</li><li>Figure 3 is a partially schematic, side elevational view of an apparatus having a support member and a pair of electrodes for removing conductive material from a microelectronic substrate.</li><li>Figure 4 is a partially schematic, side elevational view of an apparatus for removing conductive material and sensing characteristics of the microelectronic substrate from which the material is removed.</li><li>Figure 5 is a partially schematic, side elevational view of an apparatus that includes two electrolytes.</li><li>Figure 6 is a partially schematic, plan view of a substrate adjacent to a plurality of electrodes.</li><li>Figure 7 is a cross-sectional, side elevational view of an electrode and a substrate.</li><li>Figure 8A is a partially schematic, isometric view of a portion of a support for housing electrode pairs.</li><li>Figures 8B-8C are isometric views of electrodes.</li><li>Figure 9 is a partially schematic, side elevational view of an apparatus for both planarizing and electrolytically processing microelectronic substrates.</li><li>Figure 10 is a partially schematic, partially exploded isometric view of a planarizing pad and a plurality of electrodes.</li><li>Figure 11 is a partially schematic, side elevational view of an apparatus for both planarizing and electrolytically processing microelectronic substrates.</li><li>Figures 12A-B schematically illustrate a circuit and wave form for electrolytically processing a microelectronic substrate.</li><li>Figure 13 is an isometric, partially schematic, partially cutaway view of a portion of an apparatus having electrodes and a polishing medium.</li><li>Figure 14 is an isometric, partially schematic, partially cutaway view of an apparatus having electrodes and a polishing medium.</li><li>Figure 15 is an isometric, partially schematic, partially cutaway isometric view of an apparatus having electrodes and a polishing medium.</li><li>Figure 16 is an isometric, partially schematic, partially cutaway view of an apparatus having a polishing medium with oval apertures in accordance with the invention.</li><li>Figure 17 is an isometric view of an apparatus supporting a substrate for motion along a path.</li><li>Figure 18 is an isometric view of an apparatus having electrodes.</li></ul>

DETAILED DESCRIPTION

0013The present disclosure describes a method and an apparatus for removing conductive materials from a microelectronic substrate and/or substrate assembly used in the fabrication of microelectronic devices.

0014Figure 3 is a partially schematic, side elevational view of an apparatus 160 for removing conductive material from a microelectronic substrate or substrate assembly 110. The apparatus 160 includes a vessel 130 containing an electrolyte 131, which can be in a liquid or a gel state. A support member 140 supports the microelectronic substrate 110 relative to the vessel 130 so that a conductive layer 111 of the substrate 110 contacts the electrolyte 131. The conductive layer 111 can include metals such as platinum, tungsten, tantalum, gold, copper, or other conductive materials. The support member 140 is coupled to a substrate drive unit 141 that moves the support member 140 and the substrate 110 relative to the vessel 130. For example, the substrate drive unit 141 can translate the support member 140 (as indicated by arrow "A") and/or rotate the support member 140 (as indicated by arrow "B").

0015The apparatus 160 further includes a first electrode 120a and a second electrode 120b (referred to collectively as electrodes 120) supported relative to the microelectronic substrate 110 by a support member 124. The support arm 124 is coupled to an electrode drive unit 123 for moving the electrodes 120 relative to the microelectronic substrate 110. For example, the electrode drive unit 123 can move the electrodes toward and away from the conductive layer 111 of the microelectronic substrate 110, (as indicated by arrow "C"), and/or transversely (as indicated by arrow "<i>D</i>") in a plane generally parallel to the conductive layer 111. Alternatively, the electrode drive unit 123 can move the electrodes in other fashions, or the electrode drive unit 123 can be eliminated when the substrate drive unit 141 provides sufficient relative motion between the substrate 110 and the electrodes 120.

0016The electrodes 120 are coupled to a current source 121 with leads 128 for supplying electrical current to the electrolyte 131 and the conductive layer 111. In operation, the current source 121 supplies an alternating current (single phase or multiphase) to the electrodes 120. The current passes through the electrolyte 131 and reacts electrochemically with the conductive layer 111 to remove material (for example, atoms or groups of atoms) from the conductive layer 111. The electrodes 120 and/or the substrate 110 can be moved relative to each other to remove material from selected portions of the conductive layer 111, or from the entire conductive layer 111.

0017In the apparatus 160 shown in Figure 3, a distance D₁ between the electrodes 120 and the conductive layer 111 is set to be smaller than a distance D₂ between the first electrode 120a and the second electrode 120b. Furthermore, the electrolyte 131 generally has a higher resistance than the conductive layer 111. Accordingly, the alternating current follows the path of least resistance from the first electrode 120a, through the electrolyte 131 to the conductive layer 111 and back through the electrolyte 131 to the second electrode 120b, rather than from the first electrode 120a directly through the electrolyte 131 to the second electrode 120b. Alternatively, a low dielectric material (not shown) can be positioned between the first electrode 120a and the second electrode 120b to decouple direct electrical communication between the electrodes 120 that does not first pass through the conductive layer 111.

0018One feature of the apparatus 160 shown in Figure 3 is that the electrodes 120 do not contact the conductive layer 111 of the substrate 110. An advantage of this arrangement is that it can eliminate the residual conductive material resulting from a direct electrical connection between the electrodes 120 and the conductive layer 111, described above with reference to Figures 1 and 2. For example, the apparatus 160 can eliminate residual conductive material adjacent to the contact region between the electrodes and the conductive layer because the electrodes 120 do not contact the conductive layer 111.

0019The substrate 110 and/or the electrodes 120 can move relative to the other to position the electrodes 120 at any point adjacent to the conductive layer 111. An advantage of this arrangement is that the electrodes 120 can be sequentially positioned adjacent to every portion of the conductive layer to remove material from the entire conductive layer 111. Alternatively, when it is desired to remove only selected portions of the conductive layer 111, the electrodes 120 can be moved to those selected portions, leaving the remaining portions of the conductive layer 111 intact.

0020Figure 4 is a partially schematic, side elevational view of an apparatus 260 that includes a support member 240 positioned to support the substrate 110. The support member 240 supports the substrate 110 with the conductive layer 111 facing upwardly. A substrate drive unit 241 can move the support member 240 and the substrate 110, as described above with reference to Figure 3. First and second electrodes 220a and 220b are positioned above the conductive layer 111 and are coupled to a current source 221. A support member 224 supports the electrodes 220 relative to the substrate 110 and is coupled to an electrode drive unit 223 to move the electrodes 220 over the surface of the support conductive layer 111 in a manner generally similar to that described above with reference to Figure 3.

0021As shown in Figure 4, the apparatus 260 further includes an electrolyte vessel 230 having a supply conduit 237 with an aperture 238 positioned proximate to the electrodes 220. Accordingly, an electrolyte 231 can be deposited locally in an interface region 239 between the electrodes 220 and the conductive layer 111, without necessarily covering the entire conductive layer 111. The electrolyte 231 and the conductive material removed from the conductive layer 111 flow over the substrate 110 and collect in an electrolyte receptacle 232. The mixture of electrolyte 231 and conductive material can flow to a reclaimer 233 that removes most of the conductive material from the electrolyte 231. A filter 234 positioned downstream of the reclaimer 233 provides additional filtration of the electrolyte 231 and a pump 235 returns the reconditioned electrolyte 231 to the electrolyte vessel 230 via a return line 236.

0022The apparatus 260 can include a sensor assembly 250 having a sensor 251 positioned proximate to the conductive layer 111, and a sensor control unit 252 coupled to the sensor 251 for processing signals generated by the sensor 251. The control unit 252 can also move the sensor 251 relative to the substrate 110. In a further aspect of this embodiment, the sensor assembly 250 can be coupled via a feedback path 253 to the electrode drive unit 223 and/or the substrate drive unit 241. Accordingly, the sensor 251 can determine which areas of the conductive layer 111 require additional material removal and can move the electrodes 220 and/or the substrate 110 relative to each other to position the electrodes 220 over those areas. Alternatively, (for example, when the removal process is highly repeatable), the electrodes 220 and/or the substrate 110 can move relative to each other according to a pre-determined motion schedule.

0023The sensor 251 and the sensor control unit 252 can have any of a number of suitable configurations. For example, the sensor 251 can be an optical sensor that detects removal of the conductive layer 111 by detecting a change in the intensity, wavelength or phase shift of the light reflected from the substrate 110 when the conductive material is removed. Alternatively, the sensor 251 can emit and detect reflections of radiation having other wavelengths, for example, x-ray radiation. The sensor 251 can measure a change in resistance or capacitance of the conductive layer 111 between two selected points. One or both of the electrodes 220 can perform the function of the sensor 251 (as well as the material removal function described above), eliminating the need for a separate sensor 251. In still further embodiments, the sensor 251 can detect a change in the voltage and/or current drawn from the current supply 221 as the conductive layer 111 is removed.

0024The sensor 251 can be positioned apart from the electrolyte 231 because the electrolyte 231 is concentrated in the interface region 239 between the electrodes 220 and the conductive layer 111. Accordingly, the accuracy with which the sensor 251 determines the progress of the electrolytic process can be improved because the electrolyte 231 will be less likely to interfere with the operation of the sensor 251. For example, when the sensor 251 is an optical sensor, the electrolyte 231 will be less likely to distort the radiation reflected from the surface of the substrate 110 because the sensor 251 is positioned away from the interface region 239.

0025With reference to Figure 4, the electrolyte 231 supplied to the interface region 239 is continually replenished, either with a reconditioned electrolyte or a fresh electrolyte. An advantage of this feature is that the electrochemical reaction between the electrodes 220 and the conductive layer 111 can be maintained at a high and consistent level.

0026Figure 5 is a partially schematic, side elevational view of an apparatus 360 that directs alternating current to the substrate 110 through a first electrolyte 331 a and a second electrolyte 331b. The first electrolyte 331 a is disposed in two first electrolyte vessels 330a, and the second electrolyte 331 b is disposed in a second electrolyte vessel 330b. The first electrolyte vessels 330a are partially submerged in the second electrolyte 331 b. The apparatus 360 can further include electrodes 320, shown as a first electrode 320a and a second electrode 320b, each coupled to a current supply 321 and each housed in one of the first electrolyte vessels 330a. Alternatively, one of the electrodes 320 can be coupled to ground. The electrodes 320 can include materials such as silver, platinum, copper and/or other materials, and the first electrolyte 331 a can include sodium chloride, potassium chloride, copper sulfate and/or other electrolytes that are compatible with the material forming the electrodes 320.

0027The first electrolyte vessels 330a include a flow restrictor 322, such as a permeable isolation membrane formed from Teflon^™, sintered materials such as sintered glass, quartz or sapphire, or other suitable porous materials that allow ions to pass back and forth between the first electrolyte vessels 330a and the second electrolyte vessel 330b, but do not allow the second electrolyte 330b to pass inwardly toward the electrodes 320 (for example, in a manner generally similar to a salt bridge). Alternatively, the first electrolyte 331 a can be supplied to the electrode vessels 330a from a first electrolyte source 339 at a pressure and rate sufficient to direct the first electrolyte 331 a outwardly through the flow restrictor 322 without allowing the first electrolyte 331 a or the second electrolyte 330b to return through the flow restrictor 322. The second electrolyte 331 b remains electrically coupled to the electrodes 320 by the flow of the first electrolyte 331 a through the restrictor 322.

0028The apparatus 360 can also include a support member 340 that supports the substrate 110 with the conductive layer 111 facing toward the electrodes 320. For example, the support member 340 can be positioned in the second electrolyte vessel 330b. The support member 340 and/or the electrodes 320 can be movable relative to each other by one or more drive units (not shown).

0029With reference to Figure 5, the first electrolyte 331 a can be selected to be compatible with the electrodes 320. An advantage of this feature is that the first electrolyte 331 a can be less likely than conventional electrolytes to degrade the electrodes 320. Conversely, the second electrolyte 331 b can be selected without regard to the effect it has on the electrodes 320 because it is chemically isolated from the electrodes 320 by the flow restrictor 322. Accordingly, the second electrolyte 331 b can include hydrochloric acid or another agent that reacts aggressively with the conductive layer 111 of the substrate 110.

0030Figure 6 is a top plan view of the microelectronic substrate 110 positioned beneath a plurality of electrodes having several shapes and configurations. For purposes of illustration, several different types of electrodes are shown positioned proximate to the same microelectronic substrate 110; however, in practice, electrodes of the same type can be positioned relative to a single microelectronic substrate 110.

0031The electrodes 720a and 720b can be grouped to form an electrode pair 770a, with each electrode 720a and 720b coupled to an opposite terminal of a current supply 121 (Figure 3). The electrodes 770a and 770b can have an elongated or strip-type shape and can be arranged to extend parallel to each other over the diameter of the substrate 110. The spacing between adjacent electrodes of an electrode pair 370a can be selected to direct the electrical current into the substrate 110, as described above with reference to Figure 3.

0032Alternateively, electrodes 720c and 720d can be grouped to form an electrode pair 770b, and each electrode 720c and 720d can have a wedge or "pie" shape that tapers inwardly toward the center of the microelectronic substrate 110. In still another embodiment, narrow, strip-type electrodes 720e and 720f can be grouped to form electrode pairs 770c, with each electrode 720e and 720f extending radially outwardly from the center 113 of the microelectronic substrate 110 toward the periphery 112 of the microelectronic substrate 110.

0033Still alternatively, a single electrode 720g can extend over approximately half the area of the microelectronic substrate 110 and can have a semicircular planform shape. The electrode 720g can be grouped with another electrode (not shown) having a shape corresponding to a mirror image of the electrode 720g, and both electrodes can be coupled to the current source 121 to provide alternating current to the microelectronic substrate in any of the manners described above with reference to Figures 3-5.

0034Figure 7 is a partially schematic, cross-sectional side elevational view of a portion of the substrate 110 positioned beneath the electrode 720c described above with reference to Figure 6. The electrode 720c has an upper surface 771 and a lower surface 772 opposite the upper surface 771 and facing the conductive layer 111 of the substrate 110. The lower surface 772 can taper downwardly from the center 113 of the substrate 110 toward the perimeter 112 of the substrate 110 in one aspect of this embodiment to give the electrode 720c a wedge-shaped profile. Alternatively, the electrode 720c can have a plate-type configuration with the lower surface 772 positioned as shown in Figure 7 and the upper surface 771 parallel to the lower surface 772. The electrical coupling between the electrode 720c and the substrate 110 can be stronger toward the periphery 112 of the substrate 110 than toward the center 113 of the substrate 110. This feature can be advantageous when the periphery 112 of the substrate 110 moves relative to the electrode 720c at a faster rate than does the center 113 of the substrate 110, for example, when the substrate 110 rotates about its center 113. Accordingly, the electrode 720c can be shaped to account for relative motion between the electrode and the substrate 110.

0035The electrode 720c can have other shapes. For example, the lower surface 772 can have a curved rather than a flat profile. Alternatively, any of the electrodes described above with reference to Figure 6 (or other electrodes having shapes other than those shown in Figure 6) can have a sloped or curved lower surface. The electrodes can have other shapes that account for relative motion between the electrodes and the substrate 110.

0036Figure 8A is a partially schematic view of an electrode support 473 for supporting a plurality of electrodes. The electrode support 473 can include a plurality of electrode apertures 474, each of which houses either a first electrode 420a or a second electrode 420b. The first electrodes 420a are coupled through the apertures 474 to a first lead 428a and the second electrodes 420b are coupled to a second lead 428b. Both of the leads 428a and 428b are coupled to a current supply 421. Accordingly, each pair 470 of first and second electrodes 420a and 420b defines part of a circuit that is completed by the substrate 110 and the electrolyte(s) described above with reference to Figures 3-5.

0037The first lead 428a can be offset from the second lead 428b to reduce the likelihood for short circuits and/or capacitive coupling between the leads. Further, the electrode support 473 can have a configuration generally similar to any of those described above with reference to Figures 1-7. For example, any of the individual electrodes (e.g., 320a, 320c, 320e, or 320g) described above with reference to Figure 6 can be replaced with an electrode support 473 having the same overall shape and including a plurality of apertures 474, each of which houses one of the first electrodes 420a or the second electrodes 420b. The electrode support 473 can be configured to mechanically remove material from the microelectronic substrate, for example, in a manner generally similar to that described below with reference to Figures 9-11 and 13-18.

0038The electrode pairs 470 shown in Figure 8A can be arranged in a manner that corresponds to the proximity between the electrodes 420a, 420b and the microelectronic substrate 110 (Figure 7), and/or the electrode pairs 470 can be arranged to correspond to the rate of relative motion between the electrodes 420a, 420b and the microelectronic substrate 110. For example, the electrode pairs 470 can be more heavily concentrated in the periphery 112 of the substrate 110 or other regions where the relative velocity between the electrode pairs 470 and the substrate 110 is relatively high (see Figure 7). Accordingly, the increased concentration of electrode pairs 470 can provide an increased electrolytic current to compensate for the high relative velocity. Furthermore, the first electrode 420a and the second electrode 420b of each electrode pair 470 can be relatively close together in regions (such as the periphery 112 of the substrate 110) where the electrodes are close to the conductive layer 111 (see Figure 7) because the close proximity to the conductive layer 111 reduces the likelihood for direct electrical coupling between the first electrode 420a and the second electrode 420b. The amplitude, frequency and/or waveform shape supplied to different electrode pairs 470 can vary depending on factors such as the spacing between the electrode pair 470 and the microelectronic substrate 110, and the relative velocity between the electrode pair 470 and the microelectronic substrate 110.

0039Figures 8B-8C illustrate electrodes 820 (shown as first electrodes 820a and second electrodes 820b) arranged concentrically. As shown in Figure 8B, the first electrode 820a can be positioned concentrically around the second electrode 820b, and a dielectric material 829 can be disposed between the first electrode 820a and the second electrode 820b. The first electrode 820a can define a complete 360° arc around the second electrode 820b, as shown in Figure 8B, or alternatively, the first electrode 820a can define an arc of less than 360°.

0040As shown in Figure 8C, the first electrode 820A can be concentrically disposed between two second electrodes 820b, with the dielectric material 829 disposed between neighboring electrodes 820. Current can be supplied to each of the second electrodes 820b with no phase shifting. Alternatively, the current supplied to one second electrode 820b can be phase-shifted relative to the current supplied to the other second electrode 820b. The current supplied to each second electrode 820b can differ in characteristics other than phase, for example, amplitude.

0041One feature of the electrodes 820 described above with respect to Figures 8B-8C is that the first electrode 820a can shield the second electrode(s) 820b from interference from other current sources. For example, the first electrode 820a can be coupled to ground to shield the second electrodes 820b. An advantage of this arrangement is that the current applied to the substrate 110 (Figure 7) via the electrodes 820 can be more accurately controlled.

0042Figure 9 schematically illustrates an apparatus 560 for both planarizing and electrolytically processing the microelectronic substrate 110. The apparatus 560 has a support table 580 with a top-panel 581 at a workstation where an operative portion "W" of a planarizing pad 582 is positioned. The top-panel 581 is generally a rigid plate to provide a flat, solid surface to which a particular section of the planarizing pad 582 may be secured during planarization.

0043The apparatus 560 can also have a plurality of rollers to guide, position and hold the planarizing pad 582 over the top-panel 581. The rollers can include a supply roller 583, first and second idler rollers 584a and 584b, first and second guide rollers 585a and 585b, and a take-up roller 586. The supply roller 583 carries an unused or pre-operative portion of the planarizing pad 582, and the take-up roller 583 carries a used or post-operative portion of the planarizing pad 582. Additionally, the first idler roller 584a and the first guide roller 585a can stretch the planarizing pad 582 over the top-panel 581 to hold the planarizing pad 582 stationary during operation. A motor (not shown) drives at least one of the supply roller 583 and the take-up roller 586 to sequentially advance the planarizing pad 582 across the top-panel 581. Accordingly, clean pre-operative sections of the planarizing pad 582 may be quickly substituted for used sections to provide a consistent surface for planarizing and/or cleaning the substrate 110.

0044The apparatus 560 can also have a carrier assembly 590 that controls and protects the substrate 110 during planarization. The carrier assembly 590 can include a substrate holder 592 to pick up, hold and release the substrate 110 at appropriate stages of the planarizing process. The carrier assembly 590 can also have a support gantry 594 carrying a drive assembly 595 that can translate along the gantry 594. The drive assembly 595 can have an actuator 596, a drive shaft 597 coupled to the actuator 596, and an arm 598 projecting from the drive shaft 597. The arm 598 carries the substrate holder 592 via a terminal shaft 599 such that the drive assembly 595 orbits the substrate holder 592 about an axis E-E (as indicated by arrow <i>"R</i>₁<i>").</i> The terminal shaft 599 may also rotate the substrate holder 592 about its central axis F-F (as indicated by arrow "<i>R</i>₂").

0045The planarizing pad 582 and a planarizing solution 587 define a planarizing medium that mechanically and/or chemically-mechanically removes material from the surface of the substrate 110. The planarizing pad 582 used in the apparatus 560 can be a fixed-abrasive planarizing pad in which abrasive particles are fixedly bonded to a suspension medium. Accordingly, the planarizing solution 587 can be a "clean solution" without abrasive particles because the abrasive particles are fixedly distributed across a planarizing surface 588 of the planarizing pad 582. In other applications, the planarizing pad 582 may be a non-abrasive pad without abrasive particles, and the planarizing solution 587 can be a slurry with abrasive particles and chemicals to remove material from the substrate 110.

0046To planarize the substrate 110 with the apparatus 560, the carrier assembly 590 presses the substrate 110 against the planarizing surface 588 of the planarizing pad 582 in the presence of the planarizing solution 587. The drive assembly 595 then orbits the substrate holder 592 about the axis E-E and optionally rotates the substrate holder 592 about the axis F-F to translate the substrate 110 across the planarizing surface 588. As a result, the abrasive particles and/or the chemicals in the planarizing medium remove material from the surface of the substrate 110 in a chemical and/or chemical-mechanical planarization (CMP) process. Accordingly, the planarizing pad 582 can smooth the substrate 110 by removing rough features projecting from the conductive layer 111 of the substrate 110.

0047The apparatus 560 can include an electrolyte supply vessel 530 that delivers an electrolyte to the planarizing surface of the planarizing pad 582 with a conduit 537, as described in greater detail with reference to Figure 10. The apparatus 560 can further include a current supply 521 coupled to the support table 580 and/or the top-panel 581 to supply an electrical current to electrodes positioned in the support table 580 and/or the top-panel 581. Accordingly, the apparatus 560 can electrolytically remove material from the conductive layer 111 in a manner similar to that described above with reference to Figures 1-8C.

0048With reference to Figure 9, material can be sequentially removed from the conductive layer 111 of the substrate 110 first by an electrolytic process and then by a CMP process. For example, the electrolytic process can remove material from the conductive layer 111 in a manner that roughens the conductive layer 111. After a selected period of electrolytic processing time has elapsed, the electrolytic processing operation can be halted and additional material can be removed via CMP processing. Alternatively, the electrolytic process and the CMP process can be conducted simultaneously. In either of these processing arrangements, one feature of an embodiment of the apparatus 560 described above with reference to Figure 9 is that the same apparatus 560 can planarize the substrate 110 via CMP and remove material from the substrate 110 via an electrolytic process. An advantage of this arrangement is that the substrate 110 need not be moved from one apparatus to another to undergo both CMP and electrolytic processing.

0049The electrolytic process can remove relatively large amounts of material in a manner that roughens the microelectronic substrate 110, and the planarizing process can remove material on a finer scale in a manner that smoothes and/or flattens the microelectronic substrate 110.

0050Figure 10 is a partially exploded, partially schematic isometric view of a portion of the apparatus 560 described above with reference to Figure 9. As shown in Figure 10, the top-panel 581 houses a plurality of electrode pairs 570, each of which includes a first electrode 520a and a second electrode 520b. The first electrodes 520a are coupled to a first lead 528a and the second electrodes 520b are coupled to a second lead 528b. The first and second leads 528a and 528b are coupled to the current source 521 (Figure 9). The first electrode 520a can be separated from the second electrodes 520b by an electrode dielectric layer 529a that includes Teflon^™ or another suitable dielectric material. The electrode dielectric layer 529a can accordingly control the volume and dielectric constant of the region between the first and second electrodes 520a and 520b to control electrical coupling between the electrodes.

0051The electrodes 520a and 520b can be electrically coupled to the microelectronic substrate 110 (Figure 9) by the planarizing pad 582. In one aspect of this embodiment, the planarizing pad 582 is saturated with an electrolyte 531 supplied by the supply conduits 537 through apertures 538 in the top-panel 581 just beneath the planarizing pad 582. Accordingly, the electrodes 520a and 520b are selected to be compatible with the electrolyte 531. In an alternate arrangement, the electrolyte 531 can be supplied to the planarizing pad 582 from above (for example, by disposing the electrolyte 531 in the planarizing liquid 587) rather than through the top-panel 581. Accordingly, the planarizing pad 582 can include a pad dielectric layer 529b positioned between the planarizing pad 582 and the electrodes 520a and 520b. When the pad dielectric layer 529b is in place, the electrodes 520a and 520b are isolated from physical contact with the electrolyte 531 and can accordingly be selected from materials that are not necessarily compatible with the electrolyte 531.

0052With reference to Figure 10, the planarizing pad 582 can provide several advantages over some conventional electrolytic arrangements. For example, the planarizing pad 582 can uniformly separate the electrodes 520a and 520b from the microelectronic substrate 110 (Figure 9), which can increase the uniformity with which the electrolytic process removes material from the conductive layer 111 (Figure 9). The planarizing pad 582 can also have abrasive particles 589 for planarizing the microelectronic substrate 110 in the manner described above with reference to Figure 9. Furthermore, the planarizing pad 582 can filter carbon or other material that erodes from the electrodes 520a and 520b to prevent the electrode material from contacting the microelectronic substrate 110. Still further, the planarizing pad 582 can act as a sponge to retain the electrolyte 531 in close proximity to the microelectronic substrate 110.

0053Figure 11 is a partially schematic, cross-sectional side elevational view of a rotary apparatus 660 for planarizing and/or electrolytically processing the microelectronic substrate 110. The apparatus 660 has a generally circular platen or table 680, a carrier assembly 690, a planarizing pad 682 positioned on the table 680, and a planarizing liquid 687 on the planarizing pad 682. The planarizing pad 682 can be a fixed abrasive planarizing pad or, alternatively, the planarizing liquid 687 can be a slurry having a suspension of abrasive elements and the planarizing pad 682 can be a non-abrasive pad. A drive assembly 695 rotates (arrow "G") and/or reciprocates (arrow "H") the platen 680 to move the planarizing pad 682 during planarization.

0054The carrier assembly 690 controls and protects the microelectronic substrate 110 during planarization. The carrier assembly 690 typically has a substrate holder 692 with a pad 694 that holds the microelectronic substrate 110 via suction. A drive assembly 696 of the carrier assembly 690 typically rotates and/or translates the substrate holder 692 (arrows "/" and "J," respectively). Alternatively, the substrate holder 692 may include a weighted, free-floating disk (not shown) that slides over the planarizing pad 682.

0055To planarize the microelectronic substrate 110 with the apparatus 660, the carrier assembly 690 presses the microelectronic substrate 110 against a planarizing surface 688 of the planarizing pad 682. The platen 680 and/or the substrate holder 692 then move relative to one another to translate the microelectronic substrate 110 across the planarizing surface 688. As a result, the abrasive particles in the planarizing pad 682 and/or the chemicals in the planarizing liquid 687 remove material from the surface of the microelectronic substrate 110.

0056The apparatus 660 can also include a current source 621 coupled with leads 628a and 628b to one or more electrode pairs 670 (one of which is shown in Figure 11). The electrode pairs 670 can be integrated with the platen 680 in generally the same manner with which the electrodes 520a and 520b (Figure 10) are integrated with the top panel 581 (Figure 10). Alternatively, the electrode pairs 670 can be integrated with the planarizing pad 682. The electrode pairs 670 can include electrodes having shapes and configurations generally similar to any of those described above with reference to Figures 3-10 to electrolytically remove conductive material from the microelectronic substrate 110. The electrolytic process can be carried out before, during or after the CMP process, as described above with reference to Figure 9.

0057Figure 12A is a schematic circuit representation of some of the components described above with reference to Figure 10. The circuit analogy can also apply to any of the arrangements described above with reference to Figures 3-11. As shown schematically in Figure 12A, the current source 521 is coupled to the first electrode 520a and the second electrode 520b with leads 528a and 528b respectively. The electrodes 520a and 520b are coupled to the microelectronic substrate 110 with the electrolyte 531 in an arrangement that can be represented schematically by two sets of parallel capacitors and resistors. A third capacitor and resistor schematically indicates that the microelectronic substrate 110 "floats" relative to ground or another potential.

0058As shown in Figure 12A, the current source 521 can be coupled to an amplitude modulator 522 that modulates the signal produced by the current source 521, as is shown in Figure 12B. Accordingly, the current source 521 can generate a high-frequency wave 804, and the amplitude modulator 522 can superimpose a low-frequency wave 802 on the high-frequency wave 804. For example, the high-frequency wave 804 can include a series of positive or negative voltage spikes contained within a square wave envelope defined by the low-frequency wave 802. Each spike of the high-frequency wave 804 can have a relatively steep rise time slope to transfer charge through the dielectric to the electrolyte, and a more gradual fall time slope. The fall time slope can define a straight line, as indicated by high-frequency wave 804, or a curved line, as indicated by high-frequency wave 804a. Alternatively, the high-frequency wave 804 and the low-frequency wave 802 can have other shapes depending, for example, on the particular characteristics of the dielectric material and electrolyte adjacent to the electrodes 420, the characteristics of the substrate 110, and/or the target rate at which material is to be removed from the substrate 110.

0059An advantage of this arrangement is that the high frequency signal can transmit the required electrical energy from the electrodes 520a and 520b to the microelectronic substrate 110, while the low frequency superimposed signal can more effectively promote the electrochemical reaction between the electrolyte 531 and the conductive layer 111 of the microelectronic substrate 110. With reference to Figures 3-11 and 13-18 the apparatus can include an amplitude modulator in addition to a current source.

0060Figure 13 is a partially schematic, partially broken isometric view of a portion of an apparatus 1360 configured to electromechanically and/or electrochemically-mechanically remove material from the microelectronic substrate 110. The apparatus 1360 includes a polishing medium 1382 and a plurality of electrode pairs 1370. Each electrode pair 1370 can include a first electrode 1320a and a second electrode 1320b, elongated along parallel axes 1390. The electrodes 1320a and 1320b can each have a width W1 transverse to the axes 1390, and can be separated by polishing pad portions 1383. Each polishing pad portion 1383 can have a width W2 transverse to the axes 1390, and can have an elongated polishing surface 1386. The polishing surfaces 1386 of the pad portions 1383 project beyond the electrodes 1320a, 1320b. Accordingly, the electrodes 1320a, 1320b can be recessed from the polishing surfaces 1386 by a recessed distance RD, while the polishing surfaces 1386 contact the microelectronic substrate 110 to mechanically, electromechanically and/or electrochemically-mechanically polish and/or planarize or otherwise remove material from the microelectronic substrate 110. In one embodiment, the recess distance RD can have a value of from about 0.1 mm to about 10 mm. In other embodiments, the recess distance RD can have other values, depending, for example, on the particular geometries of the electrodes 1320a, 1320b and the pad portions 1383.

0061The pad portions 1383 can include flow passages 1384, each of which has an aperture 1385 proximate to the corresponding polishing surface 1386. The flow passages 1384 are coupled to a supply conduit 1337, which can in turn be coupled to an electrolytic fluid reservoir (not shown in Figure 13). In one embodiment, the flow passages 1384 can be discrete linear passages between the conduit 1337 and the polishing surface 1386, as shown in Figure 13. The pad portions 1383 can be generally porous, and the flow passages 1384 can include a network of interconnected, convoluted paths. In any of these embodiments, the flow passages 1384 can provide an electrolyte 1331 (such as an electrolytic fluid) at least proximate to an interface between the microelectronic substrate 110 and the polishing surfaces 1386.

0062The pad portions 1383 can include polyurethane materials or other suitable materials, such as those incorporated in polishing pads available from Rodel, Inc. of Phoenix, Arizona. The width W1 of the pad portions 1383 can be less than the width W2 of the interstitial electrodes 1320a, 1320b to allow for sufficient electrical communication between the electrodes 1320a, 1320b and the microelectronic substrate 110. The electrodes 1320a, 1310b and the polishing pad portions 1383 can have other relative dimensions depending on the particular geometries of these components.

0063One feature of the apparatus 1360 shown in Figure 13 is that the electrodes 1320a, 1320b are recessed from the polishing surfaces 1386. Accordingly, the electrodes 1320a, 1320b can be in electrical contact with the microelectronic substrate 110 via the electrolyte 1331 without coming into direct physical contact with the microelectronic substrate 110. The surfaces of the electrodes 1320a, 1320b facing toward the microelectronic substrate 110 are exposed to provide direct electrical contact with the electrolyte 1331. The electrodes 1320a, 1320b can be enclosed or partially enclosed with a protective film or other structure that can protect the electrodes 1320a, 1320b while still permitting electrical communication between the electrodes 1320a, 1320b and the microelectronic substrate 110 via the electrolyte 1331.

0064Another feature of the apparatus 1360 shown in Figure 13 is that the electrolyte 1331 can be provided at least proximate to (and in some embodiments, directly to) an interface between the polishing surfaces 1386 and the microelectronic substrate 110. Accordingly, the electrolyte 1331 can lubricate the interface between the microelectronic substrate 110 and the polishing surfaces 1386, chemically promote material removal from the microelectronic substrate 110, and/or convey removed particles away from the interface. At the same time, the electrolyte 1331 can fill the recesses between neighboring pad portions 1383 to provide electrical communication between the electrodes 1320a, 1320b and the microelectronic substrate 110, thus facilitating electrically removing material from the microelectronic substrate 110.

0065Figure 14 is a partially schematic, partially broken isometric view of a portion of an apparatus 1460. The apparatus 1460 includes electrode pairs 1470 with first electrodes 1420a and second electrodes 1420b. The electrodes 1420a, 1420b include flow passages 1484 having apertures 1485 for providing the electrolyte 1331 proximate to the surface of the microelectronic substrate 110. Accordingly, the flow passages 1484 are connected to a supply conduit 1447 which is in turn coupled to an electrolytic fluid source.

0066Each electrode 1420a, 1420b is spaced apart from its neighbor by a dielectric layer 1429. The dielectric layer 1429 can terminate at a plane flush with the upper faces of the electrodes 1420a, 1420b. A polishing medium 1482 can then be positioned against the electrodes 1420a, 1420b and the upwardly facing edges of the dielectric layers 1429. The polishing medium 1482 can include a sub-pad 1487 which supports pad portions 1483. Each pad portion 1483 can include a polishing surface 1486 that contacts the microelectronic substrate 110 in a manner generally similar to that described above. The sub-pad 1487 can include apertures aligned with the flow passage apertures 1485 to permit uninhibited flow of the electrolyte 1331 from the flow passages 1484. The sub-pad 1487 can have a porous composition that helps to distribute the electrolyte 1331 in the interstices between neighboring pad portions 1483. The sub-pad 1487 can be eliminated, and the pad portions 1483 can be integral with the dielectric layers 1429 in an arrangement generally similar to that described above with reference to Figure 13.

0067One feature of the apparatus 1460 shown in Figure 14 is that the apertures 1485 of the flow passages 1484 are recessed away from the interface between the microelectronic substrate 110 and the polishing surfaces 1486. Accordingly, the electrolyte 1331 can flow freely out of the flow passages 1484 despite the presence of the microelectronic substrate 110.

0068Figure 15 is an isometric view of a portion of an apparatus 1560 having electrodes 1520a, 1520b and a polishing medium 1582. The polishing medium 1582 includes polishing pad portions 1583 that project beyond the electrodes 1520a, 1520b. Each polishing pad portion 1583 includes a polishing surface 1586 and a plurality of flow passages 1584. Each flow passage 1584 has an aperture 1585 proximate to the polishing surface 1586 to provide an electrolyte 1331 proximate to an interface between the microelectronic substrate 110 and the polishing surface 1586. The pad portions 1583 can include recesses 1587 surrounding each aperture 1585. Accordingly, the electrolyte 1331 can proceed outwardly from the flow passages 1584 while the microelectronic substrate 110 is positioned directly overhead.

0069Figure 16 is an isometric view of a portion of an apparatus 1660 having a polishing medium 1682 configured in accordance with the invention. The polishing medium 1682 may include a polishing pad 1683 and sub-pad 1687 positioned against first electrodes 1620a and second electrodes 1620b. The electrodes 1620a, 1620b are separated by a dielectric layer 1629. The dielectric layer 1629 includes flow passages 1684 having apertures 1685 to deliver the electrolyte 1331 proximate to an interface between the polishing medium 1682 and the microelectronic substrate 110 (Figure 15).

0070The polishing medium 1682 includes a polishing surface 1686 having a plurality of recesses 1689. The recesses 1689 can extend entirely through the polishing pad 1683 and the sub-pad 1687 to expose both the apertures 1685 and the upwardly-facing surfaces of the electrodes 1620a, 1620b. Accordingly, the recesses 1689 can provide for an uninhibited flow of electrolyte 1331 from the apertures 1685, and can provide for electrical communication (via the electrolyte 1331) between the electrodes 1620a, 1620b and the microelectronic substrate 110. The polishing medium 1682 can further include transverse channels 1688 that connect adjacent recesses 1689 and allow the electrolyte to pass from one recess 1689 to the other without being inhibited by the microelectronic substrate 110.

0071In an embodiment with reference to Figure 16, the recesses 1689 can have a generally oval planform shape. The recesses 1689 can have other shapes (such as circular shapes) that allow for the flow of the electrolyte 1331 from the apertures 1685, and that allow for electrical communication between the electrodes 1620a, 1620b and the microelectronic substrate 110 via the electrolyte 1331. Accordingly, the recesses 1689 can extend entirely through the polishing pad 1683 and the sub-pad 1687 (as described above) or, in another embodiment, the recesses 1689 can extend through the polishing pad 1683 but not through the sub-pad 1687. The sub-pad 1687 can accordingly have a porous composition that allows the electrolyte 1331 to diffuse from the apertures 1685, through the sub-pad 1687 and into the recesses 1689.

0072Figure 17 is a top isometric view of an apparatus 1760. The apparatus 1760 includes electrode pairs 1770, each having a first electrode 1720a spaced apart from a second electrode 1720b. The apparatus 1760 can further include a polishing medium 1782 that has pad portions 1783 projecting beyond the upwardly-facing surfaces of electrodes 1720a, 1720b. Accordingly, the electrodes 1720a, 1720b and the polishing medium 1782 can remove material from the microelectronic substrate 110 in a manner generally similar to that described above.

0073The microelectronic substrate 110 can have a diameter D and the apparatus 1760 can have a length L and a width W, both of which are greater than the microelectronic substrate diameter D. Accordingly, the microelectronic substrate 110 can be moved about over the polishing medium 1782, all the while being in electrical communication with at least some of the electrodes 1720a, 1720b. As the microelectronic substrate 110 moves, different pairs of electrodes 1720a, 1720b provide electrical communication with the microelectronic substrate 110.

0074The electrodes 1720a, 1720b and the pad portions 1783 are elongated parallel to an axis 1790. The microelectronic substrate 110 can move relative to the polishing medium 1782 back and forth in a direction indicated by arrow A. An angle ⊖ between arrow A and axis 1790 can be 90° or less. ⊖ can have a value of about 45°. Accordingly, the microelectronic substrate 110 can move across a plurality of electrical fields generated by a corresponding plurality of electrode pairs 1770 during processing. An advantage of this arrangement is that the uniformity with which material is removed from the microelectronic substrate 110 can be increased relative to an arrangement in which the center of the microelectronic substrate 110 does not move relative to the polishing medium 1782.

0075Figure 18 is a top isometric view of an apparatus 1860. The apparatus 1860 has electrode pairs 1870, each of which includes a first electrode 1820a and a second electrode 1820b. Adjacent electrodes 1820a, 1820b are separated by dielectric layer 1829. The apparatus 1860 can further include a polishing medium generally similar to any of those discussed above, but not shown in Figure 18 for purposes of clarity.

0076Further the electrodes 1820a, 1820b can have a herringbone or chevron shape, and can be arranged circumferentially to define a rectangular field. For example, each electrode 1820a, 1820b can include an apex or angled portion 1821 and first and second portions 1822, 1823 extending from the apex or angled portion 1821. The first and second portions 1822, 1823 can define an included angle having a value of 180° or less. In a particular embodiment, α can have a value of about 90° and in other embodiments, α can have other values. In any of these embodiments, when the microelectronic substrate 110 (Figure 17) moves relative to the electrodes 1820a, 1820b, the microelectronic substrate 110 is exposed to a plurality of electrical fields generated by the plurality of electrode pairs 1870. As discussed above with reference to Figure 17, an advantage of this arrangement is that the uniformity with which material is removed from the microelectronic substrate 110 can be improved.

0077From the foregoing, it will be appreciated that, although a plurality of devices have been described herein for purposes of illustration, the scope of the invention is defined by the appended claims. The polishing media (shown in Figures 13-18 as facing upwardly to contact a downwardly facing surface of the microelectronic substrate) can face downwardly to contact an upwardly facing surface of the microelectronic substrate.