KR20070057271A - Method and apparatus for improved chemical mechanical planarization - Google Patents

Abstract

A polishing pad includes a guide plate having affixed thereto a porous slurry distribution layer on one side and a flexible under-layer on the other side. A plurality of polishing elements interdigitated with one another through the slurry distribution layer and the guide plate so as to be maintained in planar orientation with respect to one other and the guide plate are affixed to the flexible under-layer and each polishing element protrudes above the surface of the guide plate to which the slurry distribution layer is adjacent. Optionally, a membrane may be positioned between the guide plate and the slurry distribution layer. The polishing pad may also include wear sensors to assist in determinations of pad wear and end-of-life.

Description

Apparatus and method for improved chemical mechanical planarization work {METHOD AND APPARATUS FOR IMPROVED CHEMICAL MECHANICAL PLANARIZATION}

The present invention prioritizes US Provisional Application US 60 / 616,944, which was provisionally filed on October 6, 2004, and US Provisional Provisional Application US 60 / 639,257, which was provisionally filed on December 27, 2004, the contents of both applications See also.

FIELD OF THE INVENTION The present invention relates to the field of chemical mechanical planarization (CMP), specifically to the structural and material features of CMP polishing pads used in CMP processes.

In recent integrated circuit (IC) fabrication, a material layer is applied to a pre-built structure formed on a semiconductor wafer. A chemical mechanical planarization (CMP) process is a polishing process used to flatten the surface of a wafer and remove these layers to obtain the desired structure. CMP can be implemented for both oxides and metals and involves the use of chemical slurries that are generally applied through a polishing pad that moves relative to the wafer (eg, the polishing pad rotates cyclically with respect to the wafer). do. This smooth and flat surface is necessary to maintain the photolithographic depth of focus for subsequent steps and to ensure that metal connections do not deform over the contour step. Damascene processing requires a CMP process to remove metals such as tungsten or copper from the top surface of the insulator to form a connection structure.

The planarization / polishing performance of the pad / slurry combination is influenced by the mechanical properties of the polishing pad and the chemical properties and distribution of the slurry. Sometimes the polishing pad may be porous and / or include grooves for discharging the slurry. However, this reduces the overall strength of the polishing pad, making it more flexible, thereby reducing its planarization properties. For example, FIG. 1A shows “dishing” as a result of applying a flexible polishing pad to the wafer 100. The flexible polishing pad provides a smooth surface, but forms dishing 106 by overpolishing a soft element, such as copper layer 104, on the surface of the substrate 102. Dicing results in an undesirable reduction in metal thickness, resulting in poor device performance.

The dishing can be reduced or eliminated by using a stiffer polishing pad that can provide greater planarization. The pad can be made rigid by reducing the number of grooves and / or pores in the pad, but this can result in different results, for example, insufficient slurry discharge. As an ultimate effect, as shown in FIG. 1B showing the surface defect 108 resulting from applying a relatively hard polishing pad to the wafer 100 (eg, pit and / or scratch the surface / layer) Thereby increasing the number of surface defects 108 on the copper layer 104 and / or the substrate 102.

Whether flexible or non-flexible, the polishing pad is typically a urethane in a cast form filled with a micro-porous element or from a non-woven felt coated with polyurethane. Is prepared. During polishing, the pad surface deforms due to the polishing force. Thus, the polishing surface must be "regenerate" through a conditioning process. The conditioning process involves pressing a diamond-coated fine disk against the pad surface while the pad is rotating as during the polishing process. The diamond of the conditioning disk cuts away the top layer of the polishing pad, exposing a new polishing pad surface beneath it.

This concept is illustrated in Figures 2A-2C. In particular, FIG. 2A shows a cross-sectional side view of a polishing pad 110 prior to conventional use. The polishing pad 110 is manufactured by Rhom & Haas, Inc. As with commercially available polishing pads such as IC1000, a microelement 114, and a groove 116 are included. 2B shows the surface 112 of the polishing pad 110 after the polishing process. In particular, in the periphery of the micro member 114 where the edge is damaged due to the viscous or plastic flow of the bulk urethane material, the damaged portion 118 appears on the upper surface of the pad. 2C shows the surface 112 of the polishing pad after the conditioning process is complete. As the material is removed during the conditioning process, it can be seen that the depth of the groove 116 is lower than in the pre-use pad shown in FIG. 2A.

Through many cycles of polishing and conditioning, the overall thickness of the pad is typically worn out to the extent that the pad needs to be replaced. It is apparent to those skilled in the art that the wear rate of a pad may vary from pad to pad and may also vary from one pad batch to another. There is currently no quantitative method for determining pad wear and thus the life of the pad. Instead, the life of the pad is typically based on visual inspection of the pad to check the remaining groove depth. In the case of padless grooves, the determination of pad life is based on the time taken since the pad was first used or the number of wafers polished. Since this measuring method is not particularly accurate, it is preferable that a stable and quantitative means for determining the "life of the pad" is implemented. That is, a method based on finite wear of the pad surface would be useful in establishing a stable basis for pad replacement.

The polishing pad formed according to an embodiment of the present invention includes a guide plate having a slurry discharge layer on one side and a compressible underlayer on the other side. A plurality of abrasive elements engaged with each other through the guide plate and the slurry discharge layer are attached to the compressible underlayer by protruding each abrasive element over the surface of the guide plate adjacent the slurry discharge layer so that the guide plate and the planar direction with respect to each other are maintained. do. Optionally, a thin film may be included located between the guide plate and the slurry discharge layer. Such thin films may be conductive or nonconductive thin films and may be bonded to the guide plate by an adhesive. In some cases the thin film may be an ion exchange membrane.

The guide plate of the polishing pad is made of a non-conductive material and may include a hole in which each polishing member is received. Some of the abrasive members may have a circular cross section while others may have a triangular cross section or other shape. In any case, the abrasive member may be made of one or a combination of thermally conductive material, electrically conductive material, or non-conductive material. For example, the abrasive member may be made of conductive polymer polyaniline, carbon, graphite, or metal-filled polymer. One or more of the abrasive members may be formed in sliding contact with the wafer surface, while others are provided with a rolling tip (eg, with a rolling tip made of a polymer, metal oxide, or electrically conductive material). It may be formed to make a rolling contact with.

The slurry discharge member may comprise a plurality of slurry flow resistance members (eg pores) and may have a porosity of 10 to 90%. Preferably, but not necessarily, the slurry discharge member is coupled to the guide plate by an adhesive. In some cases the slurry discharge member may include multiple layers of different materials. For example, the slurry discharge member may include a surface layer having relatively large pores and a lower layer having relatively small pores. It is also contemplated that the functions of the slurry discharge member and the guide plate are performed by a single material. Such material may be a guide plate having a baffle or an open pore foam surface or groove to regulate slurry flow across the surface.

The polishing pad may also include a wear sensor configured to indicate pad wear and / or life.

1A shows an example of dishing caused by using a conventional polishing pad that is relatively flexible during a CMP operation.

1B shows an example of dents or scratches in the wafer / layer by using a relatively hard polishing pad during a CMP operation.

2A-2C illustrate the concept of pad wear exhibited by conventional polishing pads.

3A shows a cross-sectional side view of a circular polishing pad formed in accordance with an embodiment of the present invention for use in a CMP process.

3B shows a polishing pad similar to the polishing pad shown in FIG. 2A but including a compressible underlayer in accordance with another embodiment of the present invention.

4 shows a top view of a polishing pad having interlocking shaped polishing elements through which a slurry can flow, in accordance with another embodiment of the present invention.

5A shows a side cross-sectional view of an optical sensor 302 embedded within pad 304.

5B-5E illustrate various optical sensor configurations for use with a polishing pad formed in accordance with an embodiment of the present invention.

6A illustrates an electrochemical sensor located below the new pad surface in accordance with an embodiment of the present invention.

FIG. 6B shows the electrochemical sensor of FIG. 6A exposed due to wear of the pad.

7A shows an example of a conductive plate embedded under the surface of a polishing pad in accordance with another embodiment of the present invention.

FIG. 7B illustrates a configuration with an eddy current sensor secured to the top surface of the pad shown in FIG. 7A to assist in measuring pad wear in accordance with an embodiment of the present invention.

The following describes an improved CMP polishing pad and process for polishing a semiconductor wafer and a layered structure thereon including metal damascene structures on the wafer. The present invention considers the influence of the physical properties of the polishing pad on the quality of the CMP process. In particular, it is known that rigid pads with reduced slurry drainage produce more surface defects, while more flexible polishing pads form dishing. Although various polishing pad configurations and polishing processes are illustrated herein (eg, with specific examples of geometric ranges, ratios, and materials), the present invention removes other types of polishing pad fabrication materials and deposits. It should be understood that the same may be applied to cover the technology. In other words, the use of such other materials and techniques is considered to be within the scope of the present invention as set forth in the claims following this specification.

In addition to various polishing pad configurations, the present invention provides a method for pressing a wafer against a polishing pad under pressure and a process of compressing the wafer against a multistack polymer pad fabricated with polishing fluid comprising sub-micron particles. The movement involves the removal of the plane of the wafer plane due to the contact under the moving pressure. A polishing pad formed in accordance with an embodiment of the present invention includes a variety of elements: an abrasive fluid drainage layer, an abrasive contact or element, a guide plate, and an optional elastic flexible (ie, compressible) underlayer. In some cases, the various pad elements are made of polymers, and the polishing elements are known as Pani ^™ (available under the trademark of ORMECOM ^™ ) Conductive polymers may be made of electrically conductive materials such as polyanilyl, carbon, graphite, or metal filled polymers. In other embodiments, the polishing element may be made of a thermally conductive material such as carbon, graphite, or metal filled polymer. The slurry discharge member may be an open cell foam and the compressible underlayer may be a closed cell foam. The slurry discharge function may be accomplished by providing a groove on the guide plate or forming a baffle such that slurry flow is adjusted.

When using the pad (ie, as the pad moves relative to the wafer surface), the polishing element may make a rolling or sliding contact with the surface of the wafer. In the case of rolling contact, one or more abrasive elements may have a cylindrical body and a rolling tip. Rolling tips can be made from a variety of materials such as polymers, metal oxides or electrically conductive materials. The rolling tip abrasive element is coupled to the abrasive member in the same manner as the sliding contact abrasive element.

The polishing pads described herein can be used in various processing steps associated with CMP processes. This includes utilization in a multi-step process where slurry of various properties and multiple polishing pads are used in series and one step process where one polishing pad and one or more slurries are used throughout the entire polishing step.

In some embodiments of the present invention, the polishing pad can be formed to enable quantitative measurement of wear or simply the “end of pad life” of the pad polishing surface. For example, a "pad life" sensor or more generally a "detection sensor" may be embedded in the pad at a predetermined depth from the top surface (ie, as measured from the tip of the polishing element). As the pad wears to a predetermined thickness at which the sensor is placed or operated, the sensor detects wear and provides an input signal to the polishing system.

The life sensor may consist of an optically transparent cylindrical plug, having an upper surface covered with a reflective coating. The plug may be embedded in the pad such that the reflective end of the plug is positioned below the top surface of the pad by a predetermined height. The light source and detector are placed in a platen of the polishing apparatus through an optically transparent window. When the light beam is projected onto the plug of the new pad, the reflective surface reflects the light, indicating that the pad is still within its useful life. However, if the pad wears to a certain level and the top of the plug is approximately the same level as the exposed pad surface, the reflective surface will wear off and peel off, allowing light to pass through the pad. Thus, the change in intensity of the reflected light signal provides a feedback signal showing the wear of the pad. This change can be used to measure the "pad life" (eg, the life can be indicated by the intensity of the reflected signal being below a preset limit).

The detection hardware can be placed under or on the pad (and platen), and the optical insert can be appropriately modified to detect and analyze the reflected optical signal. One or more such plugs can be used to measure the percentage of pad life remaining. For example, different plugs corresponding to 25%, 50%, 75%, and 100% (or in different increments) of pad life may be embedded at different depths. In this way, pad wear information can be provided.

In another embodiment of the present invention, a single conical plug may be mounted flush with the pad surface such that the size of the plug opening exposed while using the pad provides information about pad wear and thus the percentage of pad life. have. In another embodiment, the plug may have a multi-step surface, which surface is exposed to varying degrees as the pad wears. The height of the steps can be adjusted to provide information regarding the percentage of pad wear.

In another embodiment of the present invention, the pad life sensor plug may comprise a screen having variable transmittance arranged in order of reflectivity. For example, the top layer may have a reflectivity of 100% (eg, full reflection to the plug) and may be disposed at the same height (or about the same) as the new pad surface. At 25% plug depth, for example, a screen with 75% reflectivity can be embedded, likewise a 50% plug depth can have a 50% reflectivity screen, and a 75% plug depth has 25%. Reflective screens may be incorporated. Of course, such relative depth and reflectance percentages can be modified to achieve similar functionality depending on the particular needs of the designer.

At the beginning of this plug / screen configuration, the projected beam will be fully reflected and the pad life will be measured at 100% (ie a new pad). As the pads wear, the top reflective layer is removed to use a 75% (and less) reflectivity screen. As each of these screens is exposed (and subsequently removed with continued wear), the remaining pad life can be measured according to the strength of the reflected signal. Thus a single element can be used to measure and monitor pad life.

In various embodiments of the present invention, the sensor may be an electrochemical sensor that includes two or more probes embedded in the pad at a predetermined depth or depths to the upper surface of the pad when new. As the pad wears and exposes the pros, the slurry provides an electrical connection between the pros, and the resulting electrical signal path is used to send or send signals to the detector to detect pad wear and consequently the life of the pads. Can be.

In another embodiment, the sensor may be a conductive plate embedded at a predetermined depth below the pad surface when it is new. An external capacitive or eddy current sensor can be used to detect distance from the conductive plate, and thus pad thickness or pad wear. The above and other embodiments of the present invention are described in more detail below.

Referring to FIG. 3A, a cross-sectional side view of a circular polishing pad 200 used in a CMP process and formed in accordance with one embodiment of the present invention is shown. In use, the polishing pad 200 rotates relative to the wafer surface to be polished, and the surface of the polishing pad contacts the wafer (typically under pressure) at the wafer contact surface 202. Slurry discharge member 204 provides flow control within the slurry passageway between abrasive elements 206.

The foundation of the polishing pad is a guide plate 208, which provides lateral support of the polishing element 206 and is made of a non-conductive material, such as a polymer or polycarbonate material. In one embodiment of the present invention, the guide plate 208 includes holes drilled out of or assembled into the guide plate 208 to receive each of the polishing elements 206. The abrasive element 206 may be secured to a surface other than the guide plate 208 (the abrasive element penetrates it); It is held in place by an adhesive such as double sided tape or epoxy. For example, the polishing element 206 may be attached to a flexible lower layer (described below) or to a housing (also described below), but in its longitudinal direction freely move in the vertical direction through the aperture of the guide plate 208. Can be. The abrasive element can be configured to have a base diameter that is greater than the diameter of the abrasive element and the guiding plate hole therethrough. For example, the body of the polishing element may have a diameter "a" and the aperture of the guide plate may have a diameter "b" so that "b" is slightly larger than "a" but smaller than the diameter "c" of the base of the polishing element. have. In essence the abrasive element will resemble a cylindrical shape on top of a flat plate. In various embodiments, the depth and spacing of the holes through the guide plate 208 may vary depending on the optimized configuration tailored to the specific CMP process. The abrasive elements are each held in a plane direction with respect to each other and with respect to the guide plate.

As shown in FIG. 3A, the polishing element 206 protrudes above the surface of the guide plate. This provides a volume for slurry discharge between the interlocking polishing elements 206 and the guide plate 208. The abrasive element can be of varying geometric shapes (such as, for example, circular and / or triangular cross sections) and can be made of one or a combination of thermally or electrically conductive and non-conductive materials. For example, the polishing element 206 may be made of an electrically or thermally conductive material such as a conductive polymer, polyaniline, carbon, graphite, or metal filled polymer, commercially known as Pani ^™ (trade name ORMECOM ^™ ). The polishing element 206 may be a conventional polishing element in sliding contact with the wafer or a portion of each element may include rolling contact. For example, each or some of the abrasive elements 206 may have a cylindrical body and a rolling tip, similar to the tip of a ballpoint pen. The rolling tip may be a polymer, metal oxide or an electrically conductive material.

In various embodiments, the polishing element 206 may protrude above the slurry discharge member by 2.5 mm or less. However, it can be seen that this value may be greater than 2.5 mm depending on the material properties of the polishing element 206 and the desired slurry flow over the surface.

In one embodiment of the present invention, the space between the interlocking polishing elements 206 may be at least partially filled with the slurry discharge member 204. The slurry discharge member 204 may include flow resistive elements such as pores or baffles or grooves (not shown) to adjust the slurry flow rate during the CMP process. In a varying embodiment, the porous slurry discharge member 204 can be placed on the guide plate 208 with a porosity of 10 to 90%. Slurry discharge member 204 may be coupled to guide plate 208 by an adhesive, such as a double sided tape. In addition, the slurry discharge member 204 may be composed of various layers of different materials to achieve a desired slurry flow rate at various depths (from the polishing surface) of the slurry discharge member 204. For example, the surface layer on the polishing surface may have larger pores to increase the amount and velocity of slurry flow on the surface, while the lower layer has smaller pores to further retain the slurry near the surface layer to assist in the adjustment of slurry flow. Can have

The polishing pad 200 is also disposed on the surface of the guide plate 208 and with each portion of the polishing element 206 extending between the guide plate 208 and the slurry discharge member 204 and into the guide plate 208. It may also include a thin film 210 to form a barrier between the spaces engaged with each other. In other cases, the thin film may be located under the guide plate 208. The thin film 210 may be a conductive or non-conductive thin film and may be coupled to the guide plate 208 by an adhesive such as double-sided tape or epoxy. For example, the thin film 210 may be an ion exchange membrane that passes electric charge but does not allow liquid to pass.

The polishing pad 200 also includes a housing 212 formed to include the guide plate 208, the thin film 210, the polishing element 206, and the slurry discharge member 204 at least partially in the housing 212 at the periphery. It may also include. The housing 212 can provide additional stability to the polishing pad 200 in addition to providing an interface to the means for rotating or handling the polishing pad 200 during the polishing operation. The housing 212 may be made of any rigid material such as polymer, metal, or the like, and may be coupled to the guide plate 208 by an adhesive such as double-sided tape or epoxy.

The thickness 214 (T) of the polishing pad 200 affects the stiffness and physical properties of the polishing pad during use. In one embodiment, the thickness may be 25 mm, but this value may vary between 3 and 10 mm depending on the material used to construct the polishing pad 200 and the type of CMP process to be performed.

Referring to FIG. 3B, a polishing pad 200A is shown. The polishing pad 200A is similar in structure to the polishing pad 200 described with reference to FIG. 2A except that the polishing pad 200A includes the compressible underlayer 216. Compressible underlayer 216 provides a pressure towards the polishing surface when compressed, among other features. Typically, the compression may be approximately 10% at 5 psi (lbs per square inch), but it can be seen that the compression may vary depending on the material used to construct the polishing pad 200 and the type of CMP process to be performed. The compressible underlayer 216 is formed by RBX Industries, Inc. It may be formed of BONDTEX ^™ manufactured by. In a varying embodiment, the compressible underlayer 216 may be included in the housing 212, external to the housing 212, or used in place of the housing 212.

4 shows a top view of a polishing pad 300, constructed in accordance with one embodiment of the present invention. The polishing elements 206 are engaged with each other throughout the polishing pad. The slurry discharge member 204 is formed by the polishing element 206 protruding from the guide plate (not shown) and spread throughout the space surrounded by the housing 212. While the space provides slurry passageway 302, slurry discharge member 204 provides a mechanism for controlling slurry flow throughout the space as described above with reference to FIG. 3A.

The placement of the polishing element 206 may vary depending on the specific CMP process and slurry discharge characteristics. In a modified embodiment, when determined by the diameter 304 (D) of each polishing element 206 and the diameter of the polishing pad 300, the polishing element 206 is 30-80% of the total surface area of the polishing pad. It may have a density. In one embodiment, the diameter 304 is at least 50 micrometers. In other embodiments, the diameter can vary between 50 micrometers and 30 mm. Typical diameters of the polishing elements are 3-10 mm.

As noted above, some polishing pads constructed in accordance with embodiments of the present invention are equipped with sensors to measure a partial or complete end of pad life (eg pad wear indicating end of life). Optical, electrochemical, or ammeter sensors can be used to measure this life / wear. Such a sensor is incorporated into the pad at one or more predetermined depths below the pad top surface. The sensor allows the transmission of an optical signal when exposed by pad wear or, in the case of an electrochemical sensor, electrical conduction to a closed circuit such that this signal is transmitted from the sensor to one or more detectors. In the case of an eddy current or capacitive sensor, a conductive plate can be embedded below the top surface of the pad, and the detector is disposed above or below the pad. Thus, the pad thickness between the sensor and the plate affects the strength of the signal detected by the detector and is used to measure part or complete termination of the pad life.

5A shows a cross-sectional side view of an optical sensor 302 embedded within pad 304. The upper surface of the optical sensor 306 is reflective such that the projected beam 308 is reflected 310 again while underneath the upper surface. Such sensors are useful in some embodiments of the present invention in which the polishing pad is configured such that the wear of the pad polishing surface or simply “pad life” can be quantitatively measured. For example, the optical sensor 302 may be a "lifetime" sensor or more generally a "reading sensor" embedded within the polishing pad 304 at a predetermined depth from the top surface of the pad (ie, as measured from the tip of the polishing element). Can act as ". When the pad wears to a predetermined thickness at which the sensor is placed or actuated, the sensor detects wear and provides an input signal to the polishing system.

Sensor 302 is an optically transparent cylindrical plug with a top surface covered with a reflective coating. The plug may be embedded in the pad 304 such that the reflective end of the plug is positioned below the top surface of the pad by a predetermined height. The light source and detector are placed in a platen of the polishing apparatus through an optically transparent window. When the light beam is projected onto the plug of the new pad, the reflective surface reflects the light, indicating that the pad is still within its useful life. However, if the pad wears to a certain level and the top of the plug is approximately the same level as the exposed pad surface, the reflective surface will wear off and peel off, allowing light to pass through the pad. Thus, the change in intensity of the reflected light signal provides a feedback signal showing the wear of the pad. This change can be used to measure the "pad life" (eg, the life can be indicated by the intensity of the reflected signal being below a preset limit).

It is apparent that the detection hardware can be placed under or on the pad (and platen), and the optical insert can be appropriately modified to detect and analyze the reflected optical signal. One or more such plugs can be used to measure the percentage of pad life remaining. For example, different plugs corresponding to 25%, 50%, 75%, and 100% (or in different increments) of pad life may be embedded at different depths. In this way, pad wear information can be provided.

In another embodiment of the present invention, a single conical plug may be mounted flush with the pad surface such that the size of the plug opening exposed while using the pad provides information about pad wear and thus the percentage of pad life. have. In another embodiment, the plug may have a multi-step surface, which surface is exposed to varying degrees as the pad wears. The height of the steps can be adjusted to provide information regarding the percentage of pad wear.

In another embodiment of the present invention, the pad life sensor plug may comprise a screen having variable transmittance arranged in order of reflectivity. For example, the top layer may have a reflectivity of 100% (eg, full reflection to the plug) and may be disposed at the same height (or about the same) as the new pad surface. At 25% plug depth, for example, a screen with 75% reflectivity can be embedded; likewise, a 50% plug depth can be embedded with a 50% reflectivity screen and 75% plug depth is 25 A screen with% reflectivity can be built in. Of course, such relative depth and reflectance percentages can be modified to achieve similar functionality depending on the particular needs of the designer.

5B-5E illustrate examples of various optical sensor configurations described above, used with polishing pad 304 in accordance with an embodiment of the present invention. Of course, other configurations of optical sensors may be used. In particular, FIG. 5B shows a multi-step optical sensor 312 having a reflective surface 306 ′, and FIG. 5C shows a single sensor 314 having multiple reflective surfaces 306 ″. 5D shows another means for incorporating a reflective surface into a single sensor. In this case the reflective surface 306 ″ ′ includes the sides of the triangular cross-sectional sensor 316. 5E shows a variable area optical sensor 318, where the cross sectional area ratio of the reflective surface 316 represents the remaining pad life ratio. It will be apparent to those skilled in the art that the sensors 312, 314, 316, 318 can be incorporated into the polishing pad at the same height as the top surface of the pad. The change in reflected optical signal strength provides information about pad wear to measure the life of the pad.

In another embodiment of the present invention, the sensor may be an electrochemical sensor comprising two or more probes embedded in the pad at a predetermined depth or depths to the upper surface of the pad when new. An example of such a configuration is shown in FIG. 6A, which shows an electrochemical sensor 402 positioned below the surface of the new pad 404. As the pad wears and exposes the pros, the slurry provides an electrical connection between the pros and the resulting electrical signal path is used to send or send signals to the detector to detect pad wear and consequently the life of the pads. Can be. 6B shows that the electrochemical sensor is exposed due to pad wear and the probe 406 is connected by the presence of the slurry element 408. Continuation of the circuit indicates that a constant pad wear has occurred.

In another embodiment of the present invention, the life sensor may be a conductive plate embedded at a predetermined depth below the pad surface when it is new. An external capacitive or eddy current sensor can be used to detect distance from the conductive plate, and thus pad thickness or pad wear. 7A shows an example of such a configuration with a conductive plate 502 embedded under the pad surface 504. A capacitive sensor plate 506 is held on the top surface of the pad to measure separation indicative of pad wear. 7B shows this configuration with an eddy current sensor 508 held on the top surface of the pad to measure the separation.

As such, improved CMP polishing pads and processes have been described for polishing semiconductor wafers and structures layered thereon, including metal damascene structures on semiconductor wafers. Although the polishing pad of the present invention and the process for using the same have been described with reference to the embodiments exemplarily described, it should be understood that the scope of the present invention should not be limited by this embodiment. Instead, the true scope of the invention should be dealt with in the light of the following claims.

Claims (32)

As a polishing pad, A guide plate having a porous slurry discharge layer attached on one side and a compressible lower layer attached on the opposite side; And A plurality of guide elements engaged with each other through the slurry discharge layer and the guide plate so as to remain in a planar direction with respect to one and the other and with respect to the guide plate, Each of the guide elements is attached to the compressive underlayer and the slurry discharge layer projects above the surface of the adjacent guide plate, Polishing pads. The method of claim 1, Further comprising a thin film disposed between the guide plate and the slurry discharge layer, Polishing pads. The method of claim 2, Characterized in that the thin film comprises a conductive thin film, Polishing pads. The method of claim 2, Characterized in that the thin film comprises a non-conductive thin film, Polishing pads. The method of claim 2, The thin film is bonded to the guide plate by an adhesive, Polishing pads. The method of claim 2, The thin film comprises an ion exchange membrane, Polishing pads. The method of claim 1, Characterized in that the guide plate is made of a non-conductive material, Polishing pads. The method of claim 1, Wherein at least some of the polishing elements have a circular cross section, Polishing pads. The method of claim 1, Wherein at least some of the polishing elements have a triangular cross section, Polishing pads. The method of claim 1, The polishing element is made of one or a combination of thermally conductive, electrically conductive, or non-conductive materials, Polishing pads. The method of claim 10, The polishing element is made of one of the conductive polymer polyaniline, carbon, graphite, or metal filled polymer, Polishing pads. The method of claim 1, At least one of the polishing elements is formed in sliding contact with the wafer surface, Polishing pads. The method of claim 1, Wherein at least one of the polishing elements is formed to make a rolling contact with the wafer surface, Polishing pads. The method of claim 13, Wherein said at least one abrasive element formed in rolling contact with the wafer surface has a cylindrical body and a rolling tip, Polishing pads. The method of claim 14, Wherein the rolling tip of the at least one abrasive element is made of one of a polymer, a metal oxide, or an electrically conductive material, Polishing pads. The method of claim 1, Wherein said slurry discharge member comprises a plurality of slurry flow resistance elements, Polishing pads. The method of claim 16, Characterized in that the slurry discharge member has a porosity of 10 to 90%, Polishing pads. The method of claim 1, The slurry discharge member is characterized in that coupled to the guide plate by an adhesive, Polishing pads. The method of claim 1, Characterized in that the slurry discharge member comprises a plurality of layers of different materials, Polishing pads. The method of claim 19, Characterized in that the slurry discharge member comprises a surface layer having a relatively large pores and a lower layer having a relatively small pores, Polishing pads. The method of claim 1, Further comprising a housing configured to include the guide plate, the polishing element, and the slurry discharge member at least partially in the periphery therein, Polishing pads. The method of claim 1, Characterized in that the polishing pad has a thickness of 3 to 10mm, Polishing pads. The method of claim 1, Characterized in that the compressible underlayer is formed of an elastomeric polymer or foam configured to provide a pressure towards the polishing surface of the polishing pad when pressed. Polishing pads. The method of claim 1, Wherein said polishing element is distributed over the surface of the polishing pad such that said polishing element collectively has a density of 30 to 80% of the total polishing pad surface area. Polishing pads. The method of claim 1, Further comprising a pad wear sensor embedded at a depth from an upper surface of the pad when measured from an operating end of one or more of the polishing elements, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises an optically transparent plug having an upper surface covered with a reflective coating, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises a plurality of optically transparent plugs embedded at different depths in the pad, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises an optically transparent conical plug mounted at the same height as the top surface of the pad surface, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises an optically transparent plug having a multi-stage surface configured to be exposed to varying degrees as the pad wears, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises an optically transparent plug arranged in an order of reflectivity and having a screen having a variable transmittance, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises an electrochemical sensor having two or more probes embedded within the pad, Polishing pads. The method of claim 25, Wherein the pad wear sensor comprises a conductive plate embedded deeply below the pad surface, Polishing pads.

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