JP2009522810A - Electrochemical processing by dynamic processing control - Google Patents

Abstract

Embodiments of the present invention generally provide a method for electrochemically removing material from a substrate. In one embodiment, a method for electrochemically processing a substrate determines a processing target for the substrate, electrochemically processes the substrate, and between a predicted processing index and an actual processing index during processing. And determining at least one process variable during processing in response to the deviation.
[Selection] Figure 7

Description

Background of the Invention

Field of Invention
[0001] Embodiments of the present invention generally relate to a method of processing a substrate, and more particularly to a method of removing material from a substrate with electrochemical assistance.

Explanation of related technology
[0002] In high density multilayer interconnect fabrication schemes, planarization techniques are used. Chemical mechanical polishing (CMP) is one technique commonly used to planarize layers of materials in interconnect fabrication schemes such as damascene and dual damascene structures. Recently, electrochemical mechanical processing has been developed to remove conductive and other materials from a substrate. Electrochemical mechanical polishing (ECMP) has proven to be very promising because the material can be planarized using low shear forces to minimize dishing of filling features. Examples of tools and methods for ECMP are disclosed in US patent application Ser. No. 10 / 980,888 and US patent application Ser. No. 10 / 941,060.

  [0003] One effect of ECMP is that the process can be adjusted to account for topographic variations following the substrate during the planarization process. For example, using the relationship between the charges removed from the conductive surface during polishing, the local polishing rate can be varied across the substrate surface to allow more material in thicker regions. It is possible to prevent the material from being excessively removed from the region where the film thickness is thinner. Such processing is described in US patent application Ser. No. 10 / 456,851.

  [0004] Although it has been demonstrated that good processing results can be obtained by the processing as described above, strict processing control is constantly required to further reduce the minute dimensions. It will be possible to make all the improvements that are longing for in this field. Therefore, there is a need for an improved planarization process.

Summary of the Invention

  [0005] Embodiments of the present invention generally provide a method for electrochemically removing material from a substrate. In one embodiment, a method of electrochemically processing a substrate determines a processing target for the substrate, electrochemically processes the substrate, and a deviation between a predicted processing index and an actual processing index during processing. And changing at least one processing variable during processing in response to the deviation.

  [0006] In another embodiment, a method of electrochemically processing a substrate determines a target profile and a predicted processing index for achieving the target profile, and the conductive surface of the substrate has a plurality of zones. Contacting a processing pad assembly comprising an electrode to establish a conductive path through an electrolyte between the conductive surface of the substrate and at least one zone of the electrode; and the conductive surface of the substrate and the electrode Independently controlling the electrical bias applied between each zone, determining the change in the predicted processing time required to achieve the target profile in at least one zone, and determining the determined change Adjusting the electrochemical treatment to compensate.

  [0007] So that the manner in which the above-described embodiments of the invention may be achieved will be more fully understood, the invention summarized above will be described in more detail below with reference to embodiments illustrated in the accompanying drawings. However, the attached drawings are only illustrative of exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and the present invention is otherwise effective. It should be noted that possible embodiments can be included.

  [0019] For ease of understanding, the same reference numerals have been used, where possible, to designate the same elements that are common to the figures. Each element of one embodiment is believed to be useful in other embodiments without further discussion.

Detailed description

  [0020] Embodiments of systems and methods for removing conductive and barrier materials from a substrate are provided. Although the embodiments described below are primarily directed to removing material from the substrate, eg, planarizing the substrate, the teachings described herein apply between the substrate and the electrodes of the system. It is believed that it can also be used to electroplate a substrate by reversing the polarity of the electrical bias applied.

apparatus
[0021] FIG. 1 is a plan view of one embodiment of a planarization system 100 having an apparatus for electrochemically processing a substrate. The exemplary system 100 generally includes a factory interface 102, a loading robot 104, and a planarization module 106. The loading robot 104 is disposed in proximity to the factory interface 102 and the planarization module 106 to facilitate transfer of the substrate 122 between them.

  [0022] To control and integrate the system 100, a controller 108 is provided. The controller 108 includes a central processing unit (CPU) 110, a memory 112, and a support circuit 114. The controller 108 is coupled to various components of the system 100 to control, for example, planarization, cleaning and transfer processes.

  [0023] The factory interface 102 generally includes a metrology module 190, a cleaning module 116, and one or more wafer cassettes 118. An interface robot 120 is used to transfer the substrate 122 between the wafer cassette 118, the cleaning module 116 and the input module 124. The input module 124 is arranged to transfer the substrate 122 between the planarization module 106 and the factory interface 102 by a gripper, such as a vacuum gripper or mechanical clamp.

  [0024] Metrology module 190 is a non-destructive measurement device suitable for providing a metric indicative of a substrate thickness profile. The measurement module 190 can include eddy current sensors, interferometers, capacitive sensors, and other suitable devices. Examples of suitable measurement modules include the Eyescan (trade name) and Eyemap (trade name) substrate measurement modules available from Applied Materials. The metrology module 190 provides a metric to the controller 108 where a target removal profile is determined for a particular thickness profile measured from the substrate.

  [0025] The planarization module 106 includes at least a first electrochemical mechanical planarization (ECMP) station 128 disposed in an environmentally controlled enclosure 188. Examples of planarization modules adapted to obtain the effects of the present invention include MIRRA®, MIRRA MESA ™, both available from Applied Materials, Santa Clara, California. No.), REFLEXION®, REFLEXION® LK and FLEXION LK Ecmp ™ chemical mechanical planarization systems. Other planarization modules, including those using processing pads, planarization webs, or combinations thereof, and those that move the substrate relative to the planarization surface in rotation, linear or other planar motion, are also effective for the present invention. Adapted to get.

  In the embodiment shown in FIG. 1, the planarization module 106 includes a first ECMP station 128, a second ECMP station 130 and a CMP station 132. By the electrochemical dissolution process in the first ECMP station 128, the conductive material on the substrate 122 can be removed in bulk. After bulk removal at the first ECMP station 128, at the second ECMP station 130, the remaining conductive material is removed from the substrate by multi-step electrochemical mechanical processing. This multi-step process portion is configured to remove residual conductive material. It is contemplated that more than one ECMP station can be used to perform a multi-step removal process after a bulk removal process performed at different stations. Alternatively, each of the first and second ECMP stations 128, 130 can be used to perform both bulk and multi-step conductive material removal in a single station. It is contemplated that the stations 128, 130, 132 can also be configured to electrochemically process the conductive layer.

  [0027] This exemplary planarization module 106 also includes a transfer station 136 and a carousel 134 disposed on the top or first side 138 of the machine base 140. In one embodiment, transfer station 136 includes an input buffer station 142, an output buffer station 144, a transfer robot 146 and a load cup assembly 148. Input buffer station 142 receives substrates from factory interface 102 by loading robot 104. The loading robot 104 is also used to return the polished substrate from the output buffer station 144 to the factory interface 102. Transfer robot 146 is used to move the substrate between buffer stations 142, 144 and load cup assembly 148.

  [0028] In one embodiment, the transfer robot 146 includes two gripper assemblies, each gripper assembly having a pneumatic gripper finger that holds the substrate at the edge of the substrate. The transfer robot 146 can simultaneously transfer substrates to be processed from the input buffer station 142 to the load cup assembly 148 while transferring processed substrates from the load cup assembly 148 to the output buffer station 144. . An example of a transfer station that can be used effectively is described in US Pat. No. 6,156,124 issued to Tobin on Dec. 5, 2000.

  [0029] The carousel 134 is disposed in the center of the base 140. The carousel 134 typically includes a plurality of arms 150 that each support a carrier head assembly 152. Two of the arms 150 shown in FIG. 1 are shown in dotted lines so that the planarization surface 126 of the transfer station 136 and the first ECMP station 128 can be seen. The carousel 134 is indexable so that the carrier head assembly 152 is moved between the flattening stations 128, 130, 132 and the transfer station 136. One carousel that can be used effectively is described in US Pat. No. 5,804,507 issued to Perlov et al.

  [0030] A conditioning device 182 is disposed on the base 140 adjacent to each of the planarization stations 128, 130, 132. The conditioning device 182 periodically conditiones the planarizing material disposed at the stations 128, 130, 132 to maintain a uniform planarization result.

  [0031] FIG. 2 shows a cross-sectional view of one of the carrier head assemblies 152 positioned over one embodiment of the first ECMP station 128. As shown in FIG. The second and third ECMP stations 130, 132 can be similarly configured. The carrier head assembly 152 generally includes a drive system 202 that is coupled to the carrier head 204. This drive system 202 generally provides at least rotational movement to the carrier head 204. The carrier head 204 is further towards the first ECMP station so that the substrate 122 held by the carrier head 204 is placed against the planarizing surface 126 of the first ECMP station 128 during processing. It is to be activated. The drive system 202 is coupled to a controller 108 that provides signals to the drive system 202 to control the rotational speed and direction of the carrier head 204.

  [0032] In one embodiment, the carrier head assembly may be a Titanium Head ™ or Titanium Profiler ™ wafer carrier manufactured by Applied Materials. In general, the carrier head 204 includes a retaining ring 224 that defines a central recess in which the housing 214 and the substrate 122 are retained. A retaining ring 224 surrounds the substrate disposed within the carrier head 204 to prevent the substrate from sliding under the carrier head 204 during processing. The retaining ring 224 can be formed of a plastic material such as PPS, PEEK, or the like, or a conductive material such as stainless steel, Cu, Au, Pd, or the like, or a combination thereof. The conductive retaining ring 224 is also intended to be electrically biased to control the electric field during ECMP. Conductive or biased retaining rings tend to slow the polishing rate near the edge of the substrate. It is contemplated that other carrier heads can be used.

  [0033] The first ECMP station 128 generally includes a platen assembly 230 that is arranged to rotate on the base 140. The platen assembly 230 is supported on the base 140 by bearings 238 such that the platen assembly 230 is rotated relative to the base 140. The area of the base 140 surrounded by the bearings 238 is open and provides electrical, mechanical, pneumatic, control signals and conduits for connections that communicate with the platen assembly 230.

  [0034] Conventional bearings, rotating unions and slips, collectively referred to as rotating coupler 276, so that electrical, mechanical, fluid, pneumatic, control signals and connections are coupled between base 140 and rotating platen assembly 230. A ring is provided. The platen assembly 230 is typically coupled to a motor 232 that provides rotational movement to the platen assembly 230. The motor 232 is coupled to the controller 108 that provides signals for controlling the rotational speed and direction of the platen assembly 230.

  [0035] The top surface 260 of the platen assembly 230 supports the processing pad assembly 222 thereon. The processing pad assembly 222 is held against the platen assembly 230 by magnetic attraction, vacuum, clamp, adhesive, or the like.

  [0036] A plenum 206 is defined in the platen assembly 230 to uniformly distribute electrolyte to the planarizing surface 126. A plurality of passages are formed in the platen assembly 230 to allow the electrolyte provided from the electrolyte source 248 to the plenum 206 to flow uniformly through the platen assembly 230 and contact the substrate 122 during processing. It is contemplated that different electrolyte compositions can be provided during different stages of processing or at different stations 128, 130, 132. It is also contemplated that the electrolyte can be applied to the surface of the pad assembly 222 via a nozzle supported on the pad assembly by a fluid distribution arm.

  [0037] The processing pad assembly 222 includes an electrode 292 and at least one planarization portion 290. Electrode 292 is typically formed from conductive materials such as stainless steel, copper, aluminum, gold, silver and tungsten, among others. The electrode 292 may be solid, electrolyte impermeable, electrolyte permeable or perforated. The electrode 292 may comprise one or more zones coupled to the power source 242. In embodiments where the electrode 292 includes multiple zones, each zone can be biased by the power supply 242 independent of the bias applied to the other zones.

  [0038] FIG. 9 is a plan view of one embodiment of an electrode 292 having multiple zones, where five concentric zones 902, 904, 906, 908, 910 are individually coupled to a power source 242. FIG. As shown. It is contemplated that the zones of electrode 292 can be other geometric configurations, numbers and arrangements in pad assembly 222.

  Returning to FIG. 2, at least one contact assembly 250 extends above the processing pad assembly 222 and is coupled to a power source 242. During processing, the contact assembly 250 electrically couples the substrate to be processed on the processing pad assembly 222 to the power source 242 so that a potential is established between the substrate and the electrode 292.

  [0040] A sensor or meter 244 is provided to detect a metric indicative of the electrochemical treatment. The meter 244 is coupled or disposed between the power source 242 and at least one of the electrodes 292 or the contact assembly 250. The meter 244 can be integrated with the power source 242. In one embodiment, the meter 244 is configured to provide the controller 108 with metrics indicative of processes such as charge, current, and / or voltage that occur on each zone of the electrode 292 (as shown in FIG. 9). Has been. Such metrics are used by the controller 108 to adjust process parameters in-situ or to perform endpoint or other process stage detection. In one embodiment, the controller 108 uses the metrics provided by the meter 244 to control the material removal rate and / or rate profile in the process field (ie, with a metric indicating the resulting processing performance). Therefore, the processing parameters for the substrate are adjusted).

  [0041] A window 246 is provided through the pad assembly 222 and / or the platen assembly 230, and the window 246 is configured to allow a sensor 254 disposed under the pad assembly 222 to sense a metric indicative of polishing performance. Has been. For example, sensor 254 may be an eddy current sensor or interferometer, among other sensors. The metric provided to the controller 108 by the sensor 254 provides information used for in-situ processing profile adjustment, endpoint detection or detection of another point in the electrochemical process. In one embodiment, the sensor 254 or interferometer can generate a collimated light beam that is directed to and strikes the side of the substrate 122 being polished during processing. The interference between the reflected signals is indicative of the thickness of the conductive layer of the material being processed. One sensor that can be used effectively is described in US Pat. No. 5,893,796 issued April 13, 1999 to Birang et al.

  [0042] An embodiment of a processing pad assembly 222 suitable for removing conductive material from the substrate 122 generally includes a planarizing surface 126 that is substantially insulating. Other embodiments of the processing pad assembly 222 suitable for removing conductive material from the substrate 122 generally include a planarized surface 126 that is substantially conductive. At least one contact assembly 250 is provided to couple the substrate to a power source 242 such that the substrate is biased with respect to the electrode 292 during processing. The hole 210 formed through the planarization layer 290 allows a conductive path between the substrate 122 and the electrode 292 to be established by the electrolyte.

  [0043] In one embodiment, the planarization portion 290 of the processing pad assembly 222 is an insulator such as polyurethane. An example of a processing pad assembly adapted to obtain the benefits of the present invention is described in US patent application Ser. No. 10 / 455,941 filed by Y. Hu et al. On June 6, 2003 (“CONDUCTIVE”). PLANARIZING ARTICLE FOR ELECTROCHEMICAL MECHANICAL PLANARIZING) and US Patent Application No. 10 / 455,895 filed by Y. Hu et al. Title).

  [0044] FIG. 3A is a partial cross-sectional view of the first ECMP station 128 through two contact assemblies 250, and FIGS. 4A and 4B are a side view and exploded view of one of the contact assemblies 250 shown in FIG. 3A. FIG. Platen assembly 230 includes at least one contact assembly 250 protruding therefrom and coupled to power source 242. The power supply 242 is adapted to bias the surface of the substrate during processing. Contact assembly 250 is coupled to platen assembly 230, a portion of processing pad assembly 222, or a separate element. Although two contact assemblies 250 are shown in FIG. 3A, any number of contact assemblies can be used and distributed in any number of configurations with respect to the centerline of the platen assembly 230. Can do.

  [0045] The contact assembly 250 is generally electrically coupled to the power source 242 through the platen assembly 230 and is movable to extend at least partially through individual holes 368 formed in the processing pad assembly 222. Has been. The position of the contact assembly 250 is selected to be a predetermined configuration across the platen assembly 230. For each given treatment, individual contact assemblies 250 can be repositioned into different holes 368, while holes that do not include contact assemblies can be inserted with stoppers 392 (as shown in FIG. 3D), or Or a nozzle 394 (as shown in FIG. 3E) that allows electrolyte to flow from the plenum 206 to the substrate. One contact assembly adapted to obtain the benefits of the present invention is described in US patent application Ser. No. 10 / 445,239 filed May 23, 2003 by Butterfield et al.

  [0046] Although the contact assembly 250 embodiment described below with respect to FIG. 3A is a rolling ball contact, the contact assembly 250 alternatively biases the substrate 122 electrically during processing. It may be a structure or assembly having a conductive top layer or surface suitable for doing so. For example, as shown in FIG. 3B, the contact assembly 250 can be made of a conductive material or, in particular, a conductive composite material such as a polymer matrix 354 or conductive coated fabric with conductive particles 356 dispersed therein (ie, A pad structure 350 can be included having an upper layer 352 formed of conductive elements dispersed together or the material comprising the upper surface being a conductive element. The pad structure 350 can include one or more holes 210 formed therethrough to distribute electrolyte to the top surface of the pad assembly. Another example of a suitable contact assembly is described in US patent application Ser. No. 10 / 980,888, filed Nov. 3, 1994 by Hu et al.

  [0047] In one embodiment, each of the contact assemblies 250 includes a hollow housing 302, an adapter 304, a ball 306, a contact element 314, and a clamp bushing 316. Ball 306 has a conductive outer surface and is movably disposed in housing 302. The ball 306 has at least a second position such that at least a portion of the ball 306 extends above the planarization surface 126 and the ball 306 is substantially flush with the planarization surface 126. And can take the position. It is also contemplated that the ball 306 can move completely below the planarized surface 126. Ball 306 is generally suitable for electrically coupling substrate 122 to power source 242. As shown in FIG. 3C, it is also contemplated that a plurality of balls 306 for biasing the substrate may be disposed in a single housing 358.

  [0048] The power supply 242 typically provides a positive electrical bias to the ball 306 during processing. During substrate planarization, the power supply 242 may optionally apply a negative bias to the ball 306 to minimize erosion of the ball 306 by processing chemicals.

  [0049] The housing 302 is configured to provide a conduit for allowing electrolyte to flow from the electrolyte source 248 to the substrate 122 during processing. The housing 302 is formed of an insulating material that is compatible with the processing chemical. A seat 326 formed on the housing 302 prevents the ball 306 from exiting the first end 308 of the housing 302. The seat 326 can optionally form one or more grooves 348 to allow fluid to flow out of the housing 302 between the ball 306 and the seat 326. By maintaining fluid flow through the ball 306, the tendency of the processing chemical to erode the ball 306 can be minimized.

  [0050] Contact element 314 is coupled between clamp bushing 316 and adapter 304. The contact element 314 is generally configured to electrically connect the adapter 304 and the ball 306 substantially or completely over a range of ball positions within the housing 302. In one embodiment, the contact element 314 is configured as a spring shape.

  [0051] In the embodiment shown in FIGS. 3 and 4A, 4B and shown in detail in FIG. 5, the contact element 314 has an annular base from which a plurality of flexible strips 344 extend in a polar array. 342. These flexible strips 344 are generally formed of a resilient conductive material suitable for use with processing chemicals. In one embodiment, the flexible strip 344 is formed of gold-plated beryllium copper.

  [0052] Returning to FIGS. 3A and 4A, 4B, the clamp bushing 316 includes a flared head 424 from which a threaded post 426 extends. The clamp bushing 316 may be formed from an insulative or conductive material, or a combination thereof, and in one embodiment is formed from the same material as the housing 302. The flared head 424 maintains the flexible pieces 344 at an acute angle with respect to the centerline of the contact assembly 250 so that the flexible pieces 344 of the contact element 314 extend around the surface of the ball 306. Placed so that the flexible pieces 344 are not bent, restrained and / or damaged during assembly of the contact assembly 250 and over the range of movement of the ball 306. To do.

  [0053] The ball 306 may be solid or hollow and is typically formed of a conductive material. For example, the ball 306 is formed of a polymer material filled with a conductive material such as metal, conductive carbon, or graphite, among metals, conductive polymers, or conductive materials. Alternatively, the ball 306 is formed of a solid or hollow core that is coated with a conductive material. The core may be non-conductive and at least partially covered with a conductive cover.

  [0054] The ball 306 is generally actuated toward the planarization surface 126 by at least one of a spring, a floating, or a flow force. In the embodiment shown in FIG. 3, the passage formed through adapter 304 and clamp bushing 316 and the flow from electrolyte source 248 through platen assembly 230 causes ball 306 to move into contact with the substrate during processing. It is done.

  [0055] FIG. 6 is a cross-sectional view of one embodiment of a second ECMP station 130. As shown in FIG. Optionally, the first and third stations 128, 132 may be similarly configured. The second ECMP station 130 generally includes a platen 602 that supports a fully conductive processing pad assembly 604. The platen 602 may be configured similarly to the platen assembly 230 as described above to distribute electrolyte through the processing pad assembly 604, or the platen 602 may apply electrolyte to the planarized surface of the processing pad assembly 604. A fluid distribution arm 606 configured to supply may be adjacently disposed. This second ECMP station 130 also includes a meter 244 or sensor 254 (shown in FIG. 2) for obtaining at least one metric indicative of the process for endpoint detection and / or process control. Including at least one.

  [0056] In one embodiment, the processing pad assembly 604 includes an interposer pad 612 sandwiched between a conductive pad 610 and an electrode 614. Electrode 614 is generally configured as described with respect to electrode 292. The conductive pad 610 is substantially conductive across its upper treated surface, and is generally a conductive material, such as a polymer matrix or conductive coated fabric with conductive particles dispersed therein. It is formed of a conductive composite material (ie, the conductive elements are dispersed integrally or the material that includes the planarized surface is the conductive element). The conductive pad 610, the intervening pad 612, and the electrode 614 can be formed as a single replaceable assembly. The processing pad assembly 604 is typically permeable or perforated to allow electrolyte to pass between the electrode 614 and the top surface 620 of the conductive pad 610. In the embodiment shown in FIG. 6, the processing pad assembly 604 is perforated with holes 622 to allow electrolyte to flow therethrough. In one embodiment, conductive pad 610 is composed of particles in a conductive material disposed in a polymer matrix disposed in a conductive fiber, such as a polymer matrix disposed in a woven copper-coated polymer. The conductive pad 610 can also be used for the contact assembly 250 in the embodiment of FIG. 3C.

  [0057] A conductive foil 616 may additionally be disposed between the conductive pad 610 and the subpad 612. The foil 616 is coupled to the power source 242 to evenly distribute the voltage applied by the power source 242 across the conductive pad 610. In embodiments that do not include such a conductive foil 616, the conductive pad 610 can be coupled directly to the power source 242, for example, via a terminal integral with the pad 610. The pad assembly 604 can also include an interposer pad 618 that provides mechanical strength to the upper conductive pad 610 along with the foil 616. Examples of suitable pad assemblies are described in the aforementioned US patent application Ser. Nos. 10 / 455,941 and 10 / 455,895.

Method for electroprocessing metal and barrier layers
[0058] FIG. 7 shows a flow diagram of one embodiment of a method 700 for electroprocessing a substrate having an exposed conductive layer, as implemented in the system 100 described above or other suitable processing system. Yes. The method 700 is generally stored in the memory 112 of the controller 108, typically as a software routine. This software routine may also be stored and / or executed on a second CPU (not shown) located remotely from the hardware controlled by CPU 110. Although the process of the present invention is described as being implemented as a software routine, some of the method steps described herein may be performed in hardware or performed by a software controller. May be. Thus, the present invention may be implemented in software, such as executed in a computer system, implemented in hardware as an application specific integrated circuit or other type of hardware implementation, or software And may be implemented in combination with hardware.

  [0059] The method 700 begins at step 702, where a thickness profile of a conductive film on a substrate to be processed is determined. This thickness profile may be determined by the metrology module 190 disposed in the factory interface 102 or may be provided from another source. This thickness profile is derived from measurements related to the unique substrate that allow the generation of a thickness map and / or shape, but is obtained after the deposition process or as an endpoint index obtained in the deposition process. Do not be confused with spot thickness. Thus, each substrate in the batch has an individual thickness profile.

  [0060] In step 704, a target profile for each substrate is generated based on the information obtained in step 702. This target profile is generally the amount of material to be removed at various locations across the substrate so that a flat surface is obtained. For example, the target profile has a predetermined layer defined on the substrate with a thick film layer (relative to other areas of the film as determined by the following profile information) and is therefore flat. This indicates that more material must be removed than other areas of the substrate to obtain a smooth surface. By processing to achieve the target profile, thinner film regions are processed at a rate that prevents over-polishing or dishing, eg, undesired material removal from within features such as trenches.

  [0061] In step 706, starting process parameters such as voltage, current, time, etc. are set to achieve the target profile from the incoming profile. This generally sets the duration and voltage (and / or current) required to remove a predetermined amount of charge (indicating film thickness) from the substrate. One embodiment for setting parameters to remove each calculated amount of charge from a substrate in different zones by electrochemical processing is described in the aforementioned US patent application Ser. No. 10 / 456,851. Yes. It is contemplated that these processing parameters can be set by other methods.

  [0062] In step 708, the substrate is electrochemically treated to remove at least a portion of the conductive material film (eg, layer) therefrom. The conductive film can be tungsten, copper, a layer having both exposed tungsten and copper, or other conductive material.

  [0063] In one embodiment, the electrochemical processing step 708 includes moving the substrate 122 held by the carrier head 204 onto a processing pad assembly 222 disposed at the first ECMP station 128. Although the pad assembly shown in FIGS. 2, 3A, 4A, 4B, and 5 is used in one embodiment, alternatively, the pad and contact assembly as shown in FIGS. 3B and 3C. It is intended that can be used. It is also contemplated that the electrochemical processing step 708 can be performed at the second ECMP station 130 in a manner similar to that described below.

  [0064] The carrier head 204 is lowered toward the platen assembly 222 to bring the substrate 122 into contact with the upper surface of the pad assembly 222. The substrate 122 is pressed against the pad assembly 222 with a force less than about 2 pounds per square inch (psi). In one embodiment, this force is about 0.3 pounds per square inch.

  [0065] Relative motion is provided between the substrate 122 and the processing pad assembly 222. In one embodiment, the carrier head 204 is rotated at about 30-60 revolutions per minute while the pad assembly 222 is rotated at about 7-35 revolutions per minute.

  [0066] An electrolyte is supplied to the processing pad assembly 222 to establish a conductive path between the substrate 122 and the electrode 292. The electrolyte typically includes at least one of nitric acid, phosphoric acid, and ammonium citrate.

  [0067] The power supply 242 provides a bias voltage between the electrode 292 and the substrate in contact with the top surface of the pad assembly 222. In one embodiment, the applied voltage is less than about 6.0 volts. In embodiments where copper is the material to be treated, this applied voltage is less than about 3.0 volts. In embodiments where tungsten is the material to be processed, this applied voltage is less than about 3.5 volts.

  [0068] One or more of the contact elements 250 of the pad assembly 222 are in contact with the substrate 122 such that a voltage is coupled thereto. The electrolyte filling the hole 210 between the electrode 292 and the substrate 122 provides a conductive path between the power source 242 and the substrate 122, performs an electrochemical mechanical planarization process, and performs anodic dissolution in step 708. The conductive material on the substrate is removed. The process of step 708 generally has a copper removal rate of about 6000 K / min, while a tungsten removal rate of about 4000 K / min is obtained.

  [0069] The bias for each zone of electrode 292 is individually controlled based on the parameters initially set in step 706. This bias is controlled by adjusting the voltage applied between the substrate and the electrode 292. Thereby, it becomes possible to adjust the process with respect to the specific shape and / or film thickness of the substrate to be processed. Since the resistance of the film to be removed generally increases as the film becomes thinner, the current through the zone (and therefore the rate of material removal in the region of the substrate to be processed across the zone) Is reduced.

  [0070] In step 710, at least one processing parameter is adjusted to correct a change in processing rate in each zone, for example, as indicated by a change in current flowing through each zone. Such adjustments made in step 710 compensate for resistance increases or other factors that cause rate changes to prevent the current from being reduced from the desired amount to obtain the target profile. The processing rate in each zone is maintained at or near the target level.

  [0071] In one embodiment, this adjustment step 710 includes three sub-steps 712, 714, 716. In sub-step 712, at least one metric indicative of processing such as charge, current and / or voltage is provided to the controller 108 by the meter 244 (or meter 244). In one embodiment, meter 244 provides the amount of charge that is removed from the substrate in each zone.

  [0072] In sub-step 714, a metric indicating the processing in each zone is compared to the processing parameters set in step 706 (or values set in the previous iteration) to determine the error. Substrate 714 may process the actual processing index measured and / or sensed in step 712 with the desired index, eg, the parameter set in step 706 (or set in the iteration phase immediately prior to step 710). Compare with the expected index value. For example, step 706 is (X) for the desired charge in the first zone of electrode 292 to achieve the target profile, while the metric sensed during processing in step 712 is (Y). Can be determined. Thus, in this example, the error between the desired metric and the measured metric is (XY). It is believed that one or more metrics can be compared.

  [0073] In sub-step 716, the processing parameters for performing the processing in step 708 are adjusted to take into account the deviation between the predicted and measured parameters, and thus the processing trajectory is adjusted to achieve the target profile. Maintained. In the embodiment described above, at least one processing parameter is adjusted.

  [0074] In one embodiment, the voltage applied between the substrate and each zone of the electrode 292 is adjusted to compensate for changes during processing and to maintain its processing trajectory to produce the desired target profile. The In this example, the regulated voltage (eg, the voltage modified in step 712) can be expressed in the following equation:

here,
Vi (t + Δt) is an adjustment voltage for the zone i of the electrode 292.

  Vi (t) is the voltage at the previous sample (ie, repeated first in step 706 and then in sub-step 712).

  i is the zone of the electrode 292.

Ie _i is the current error for zone i.

Ce _i is the charge error for zone i.

  P, I and D are the proportional, integral and derivative constants selected for the processing cell of the tool. These are determined empirically or by calculation.

  [0075] Factors considered during the determination of the P, I, and D constants include initial voltage, saturation voltage, thickness of the next film to be processed and the desired removal rate. It has been observed that a large saturation voltage, defined as the maximum voltage change allowed at each tuning iteration, contributes to process instability. In one embodiment, this saturation voltage is set to be less than about 0.5 volts, for example, less than about 0.2 volts, thereby preventing process instability during repetitive process adjustments. The constant D is set to zero for low current processing and set to a higher value for high current processing. In the case of the process used to achieve the result shown in FIG. 8B as described further below, this constant D is set to approximately zero, while the constant P is set to approximately 0.2. It was done.

  [0076] Steps 708 and 710 are repeated as illustrated by arrow 718 until an endpoint is reached in step 720. The endpoint is determined using the process metric provided by meter 244. In another embodiment, optical techniques such as an interferometer using sensor 254 may be used. Alternatively, the residual thickness may be measured directly, or by subtracting the amount of material removed from a given starting film thickness, for example, removing the charge removed from the substrate. It may be calculated by comparing with the target charge correlated to the target profile. Examples of endpoint techniques that can be used are US patent application Ser. No. 10 / 949,160, filed Sep. 24, 2004, US patent application Ser. No. 10/056, filed Jan. 22, 2002. 316, and US patent application Ser. No. 10 / 456,851, filed Jun. 6, 2002.

  [0077] After reaching the endpoint in step 720, optionally, an overpolish is performed in step 722. This overpolish step 722 typically has a duration of about 15 seconds to about 30 seconds to remove residual material from the surface of the substrate.

  [0078] In another embodiment, the adjustment process 710 can compare the predicted time to reach the target criteria in each zone. If the difference between the predicted time in the fastest zone and the predicted time in the slowest zone is greater than the predetermined period, the process is completed within the predetermined period (eg, the target in each zone is achieved) As such, coordinate processing in one or more zones. By approaching the completion of processing in all the zones, it is possible to substantially prevent substances from being erroneously removed from the substrate on the zone that has reached the target earlier. In addition, since the process is periodically modified, changes in process completion time in any zone can be considered across all zones, thus minimizing the process time.

  [0079] FIGS. 8A and 8B show graphs 800, 820 illustrating the conventional electrical process (FIG. 8A) and the electrical process of the present invention (FIG. 8B), respectively. In the conventional process of FIG. 8A, time is plotted on the X-axis 802. On the Y axis 804, current and charge are plotted. Plots 806, 808, and 810 illustrate charge measurements over time in the first processing zone, the second processing zone, and the third processing zone, respectively. Plots 812, 814, and 816 illustrate current measurements in the first zone, the second zone, and the third zone, respectively, over time. The vertical portion of each charge trace 806, 808, 810 indicates when the target has been reached. As indicated by arrow 818, the arrival of the first zone endpoint (represented by trace 806) deviates significantly from the arrival of the third zone endpoint (represented by trace 810). These end point mismatches result in undesirable polishing in the completion zone.

  [0080] The process of the present invention is illustrated in Figure 8B with time on the X-axis 802 and current and charge on the Y-axis 804. Plots 826, 828, and 830 illustrate charge measurements over time for the first processing zone, the second processing zone, and the third processing zone, respectively. Plots 832, 834, and 836 illustrate current measurements in the first zone, the second zone, and the third zone, respectively, over time. The vertical portion of each charge trace 826, 828, 830 indicates when the target is reached. When the endpoint of the first zone (represented by trace 826) is reached, the endpoint of the third zone is reached (by adjusting its processing in response to the comparison between the measured and predicted process metrics ( The endpoint deviation between the fastest and slowest processing zones is minimized, as shown by arrow 838. Deviations between these endpoints can be further minimized by adjusting the process to compensate for changes in the predicted processing time in each zone.

  [0081] Accordingly, the present invention provides an improved apparatus and method for electrochemical planarization of a substrate. The apparatus can efficiently perform bulk and residual metal and barrier material removal from the substrate using a single tool. By using electrochemical processing for the entire metal and barrier removal sequence, conductor erosion and dishing can be effectively reduced while minimizing oxide loss during processing. It is believed that methods and apparatus as taught herein can be used to deposit material on a substrate by reversing the polarity of the bias applied to the electrodes and substrate.

  [0082] While various embodiments of the invention have been described above, other and further embodiments of the invention can be devised without departing from the basic scope thereof, and thus the invention Is defined by the description of the scope of claims.

1 is a plan view of an electrochemical mechanical planarization system. 2 is a cross-sectional view of one embodiment of a first electrochemical mechanical planarization (ECMP) station of the system of FIG. FIG. 3 is a partial cross-sectional view of a bulk ECMP station through two contact assemblies. FIG. 6 is a perspective view of another embodiment of a contact assembly. FIG. 6 is a perspective view of another embodiment of a contact assembly. It is sectional drawing of a plug. It is sectional drawing of a plug. FIG. 6 is a side view of one embodiment of a contact assembly. It is a disassembled parts arrangement perspective view of one embodiment of a contact assembly. 1 is an embodiment of a contact element. FIG. 6 is a cross-sectional view of another embodiment of another ECMP station. FIG. 2 is a flow diagram of one embodiment for electrochemical processing. 2 shows a graph illustrating a comparison between a conventional electrochemical process and an electrochemical process performed according to the present invention. 2 shows a graph illustrating a comparison between a conventional electrochemical process and an electrochemical process performed according to the present invention. 1 is a plan view of one embodiment of a zone-type electrode suitable for use in the electrochemical processing of the present invention. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Flattening system, 102 ... Factory interface, 104 ... Loading robot, 106 ... Flattening module, 108 ... Controller, 110 ... Central processing unit (CPU), 112 ... Memory, 114 ... Support circuit, 116 ... Cleaning module, 118 ... wafer cassette, 120 ... interface robot, 122 ... substrate, 124 ... input module, 126 ... planarized surface, 128 ... first electrochemical mechanical planarization (ECMP) station, 130 ... second ECMP station, 132 ... CMP Station, 134 ... Carousel conveyor, 136 ... Transfer station, 138 ... Upper or first side of machine base, 140 ... Machine base, 142 ... Input buffer station, 144 ... Output buffer station, 146 ... Transfer Bot, 148 ... load cup assembly, 150 ... arm, 152 ... carrier head assembly, 182 ... conditioning device, 188 ... enclosure, 190 ... measurement module, 202 ... drive system, 204 ... carrier head, 206 ... plenum, 210 ... hole , 214 ... Housing, 222 ... Processing pad assembly, 224 ... Retaining ring, 230 ... Platen assembly, 232 ... Motor, 238 ... Bearing, 242 ... Power supply, 244 ... Meter, 246 ... Window, 248 ... Electrolyte source, 250 ... Contact assembly 254 ... sensor, 260 ... upper surface of platen assembly, 276 ... rotating coupler, 290 ... flattened part, 292 ... electrode, 302 ... hollow housing, 304 ... adapter, 306 ... ball, 308 ... of housing 1 end, 314 ... contact element, 316 ... clamp bushing, 326 ... sheet, 342 ... annular base, 344 ... flexible strip, 348 ... groove, 350 ... pad structure, 352 ... top layer, 354 ... polymer matrix 356 ... conductive element, 358 ... single housing, 368 ... hole, 392 ... stopper, 394 ... nozzle, 424 ... flared head, 426 ... threaded post, 602 ... platen, 604 ... treatment pad assembly, 606 ... fluid Distributing arm, 610 ... conductive pad, 612 ... intervening pad (subpad), 614 ... electrode, 616 ... conductive foil, 618 ... intervening pad, 620 ... upper surface of conductive pad, 622 ... hole, 902 ... concentric of electrode Zone, 904 ... Concentric zone of electrode, 906 ... Concentric zone of electrode, 908 ... Concentric zone of electrode 910 ... Concentric zone of electrodes

Claims (25)

In a method for processing a substrate,
Determining a processing target for the substrate;
Electrochemically treating the surface of the substrate;
Determining a deviation between a predicted process indicator and an actual process indicator during processing;
Changing at least one process variable during processing in response to the deviation;
With a method.   The method of claim 1, wherein determining the processing target further comprises determining a profile for the surface to be processed.   The method of claim 1, wherein determining the processing target further comprises determining a film thickness at a plurality of locations on the substrate.   The method of claim 3, wherein the thickness is determined by a non-destructive measurement technique.   The method of claim 4, wherein the non-destructive measurement technique is at least one of eddy current sensing, capacitive sensing, or interferometry.   The method of claim 1, wherein changing the at least one process variable further comprises adjusting a current for performing the electrochemical process. The step of electrochemically treating the surface comprises:
Pressing the surface of the substrate against an abrasive material;
Establishing a relative motion between the abrasive material and the surface of the substrate;
The method of claim 1, further comprising: The step of electrochemically treating the surface of the substrate comprises:
Biasing the surface of the substrate against an electrode spaced from the surface of the substrate;
Providing an electrolyte in contact with the electrode and the surface of the substrate;
The method of claim 1, further comprising: The step of electrochemically treating the surface of the substrate comprises:
Pressing the surface of the substrate against the surface of the conductive polymer in the presence of an electrolyte;
Applying an electrical bias to the surface of the substrate through the conductive polymer surface;
Providing relative motion between the surface of the substrate and the surface of the conductive polymer;
The method of claim 1, further comprising: The step of electrochemically treating the surface of the substrate comprises:
Pressing the surface of the substrate against an insulating polymer surface supported by a platen;
Establishing a conductive path via an electrolyte between the surface of the substrate and the electrode supported by the platen;
Applying an electrical bias to the surface of the substrate via electrical contacts extending from the platen;
Providing relative motion between the surface of the substrate and the surface of the insulating polymer;
The method of claim 1, further comprising:   The method of claim 1, wherein the determining step further comprises comparing a predicted current with a measured current.   The method of claim 1, wherein the determining step further comprises comparing a predicted charge removed from the substrate with a measured charge.   The method of claim 1, wherein the determining step further comprises comparing a predicted thickness with an actual thickness during the electrochemical process.   The method of claim 1, wherein changing the at least one process variable further comprises adjusting a voltage at which the electrochemical process is performed.   The step of changing the at least one process variable adjusts the process variable in the first process zone independently of the process variable for the second process zone and controls the electrochemical removal rate in each process zone independently. The method of claim 1, further comprising the step of: The voltage V _i for performing the electrochemical process is changed in response to the deviation D _i , where V _i is a vise voltage applied to each processing zone of the processing system in which the electrochemical process is performed. , D _i is the deviation between the predicted processing index and the actual processing index in each processing zone of the processing system, and i is the number of processing zones arranged in the lateral direction in the processing system, The method of claim 1. Vi is expressed by the following equation:
here,
Ie _i is the current error for zone i,
Ce _i is the charge error for zone i,
P, I and D are constants,
The method of claim 16. Determining a change in predicted processing time during processing;
Adjusting the electrochemical treatment to compensate for the determined change;
The method of claim 1, further comprising:   The step of adjusting the electrochemical process to compensate for the determined change maintains a deviation in endpoint arrival between the fastest and slowest process zones within a predetermined period of time. The method of claim 18 further comprising the step.   The method of claim 1, further comprising setting processing parameters based on a thickness profile that follows a film to be processed on the substrate to achieve the processing target. In a method for processing a substrate,
Determining a target profile and a predictive processing indicator for achieving the target profile;
Contacting the conductive surface of the substrate against a processing pad assembly comprising an electrode having a plurality of zones;
Establishing a conductive path via an electrolyte between the conductive surface of the substrate and at least one zone of the electrode;
Independently controlling the electrical bias applied between the conductive surface of the substrate and each zone of the electrode;
Determining a deviation between a predicted process indicator and an actual process indicator during processing;
Changing at least one process variable during processing in response to the deviation;
With a method. Determining a change in predicted processing time during processing;
Adjusting the electrochemical treatment to compensate for the determined change;
The method of claim 21, further comprising:   The step of adjusting the electrochemical process to compensate for the determined change maintains a deviation in endpoint arrival between the fastest and slowest process zones within a predetermined period of time. 24. The method of claim 22, further comprising the step. In a method for processing a substrate,
Determining a target profile and a predictive processing indicator for achieving the target profile;
Contacting the conductive surface of the substrate against a processing pad assembly comprising an electrode having a plurality of zones;
Establishing a conductive path via an electrolyte between the conductive surface of the substrate and at least one zone of the electrode;
Independently controlling the electrical bias applied between the conductive surface of the substrate and each zone of the electrode;
Determining a change in predicted processing time required to achieve the target profile in at least one zone;
Adjusting the electrochemical treatment to compensate for the determined change;
With a method. The step of adjusting the electrochemical process to compensate for the determined change maintains a deviation in endpoint arrival between the fastest and slowest process zones within a predetermined period of time. The method of claim 24, further comprising the step.