| Chemical mechanical polishing pad -> Monitor Keywords |
|
|
  Chemical mechanical polishing padUSPTO Application #: 20070224925Title: Chemical mechanical polishing pad Abstract: A polishing pad has polishing elements of at least two different types of materials, each having a different coefficient of friction, and arranged over a surface of the pad so as to provide a non-planar material removal profile for the pad. The polishing elements may be arranged to provide different material removal profiles, such as an edge-fast, edge-slow, center-fast or center-slow material removal profile. (end of abstract)
Agent: Sonnenschein Nath & Rosenthal LLP - Chicago, IL, US Inventor: Rajeev Bajaj USPTO Applicaton #: 20070224925 - Class: 451530 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070224925. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001]The present application is a nonprovisional of, claims priority to an incorporates by reference U.S. provisional patent application No. 60/784,263, filed 21 Mar. 2006. FIELD OF THE INVENTION [0002]The present invention relates to the field of chemical mechanical planarization (CMP) and relates specifically to a CMP polishing pad conditioning apparatus and its method of use. BACKGROUND [0003]In modem integrated circuit (IC) fabrication, layers of material are applied to embedded structures previously formed on semiconductor wafers. Chemical mechanical planarization (CMP) is an abrasive process used to remove these layers and polish the surface of a wafer to achieve the desired structure. CMP may be performed on both oxides and metals and generally involves the use of chemical slurries applied in conjunction with a polishing pad in motion relative to the wafer (e.g., pad rotation relative to the wafer). The resulting smooth flat surface is necessary to maintain the photolithographic depth of focus, for subsequent steps and to ensure that the metal interconnects are not deformed over contour steps. Damascene processing requires metal, such as tungsten or copper, to be removed from the top surface of a dielectric to define interconnect structures. [0004]Polishing pads are typically made of urethanes, either in cast form and filled with micro-porous elements, or from non-woven felt coated with polyurethanes. One aspect of conventional polishing pads is that the polishing pad surface is a single continuous sheet of material, which may be grooved or perforated to facilitate slurry distribution across the surface. [0005]During polishing, the polishing pad is rotated while contacting the wafer, which is also rotated, thus effecting polishing. One of the aspects of this process is that as a pad moves under a wafer, there is a sudden change in pad compression. This gives rise to "edge effects" on the wafer, wherein the material removal rate at the edge of the wafer is different from the material removal rate across the rest of the wafer. [0006]Another aspect of existing polishing pads is that they have no ability to modulate the removal profile across the width of a wafer. In advanced processing processes there are multiple films being deposited, each of which has a specific deposition profile. For example, electroplated copper films tend to be edge thick, while some dielectric films tend to have a smooth "M" or "W" profile. In cases of critical process modules, such as copper and STI polishing, this can lead to over-polishing to complete processing across the width of the wafer. For advanced technologies, the available over-polish margins are shrinking rapidly and, in some cases, allow for less than 5% of the polish time. This leads to loss of performance or, worse, loss of yield for some parts. There is thus a need for the ability to tune the removal profile of a pad in polishing processes to minimize over-polishing. SUMMARY OF THE INVENTION [0007]An embodiment of the invention provides a polishing pad having polishing elements of at least two different types of materials, each having a different coefficient of friction, and arranged over a surface of the pad so as to provide a non-planar material removal profile for the pad. The polishing elements may be arranged to provide an edge-fast, edge-slow, center-fast or center-slow material removal profile. [0008]A further embodiment of the invention provides a polishing pad having a plurality of polishing elements of at least two different materials, each having a different coefficient of friction, and arranged in different densities across a surface of the pad so as to provide a non-planar material removal profile for the pad. [0009]Still another embodiment of the invention provides a polishing pad having a plurality of polishing elements, some of which are polyurethane and others of which are Delrin. The polishing elements may be arranged in a radial or other manner across a surface of the pad such that those of the polishing elements which are Delrin comprise approximately 5-50% of the total number of polishing elements in locations corresponding to areas of the pad configured to provide relatively lower material removal rates than other areas of the pad. The overall density of polishing elements may be uniform per unit area of the pad and/or the polishing elements may be laid out in a uniform radial arrangement. In some cases, both the Delrin and polyurethane polishing elements may have a common shape and size. BRIEF DESCRIPTION OF THE DRAWINGS [0010]The present invention is illustrated by way of example, and not limitation, in the figures of the accompanying drawings, in which: [0011]FIG. 1A illustrates a side cut-away view of a conventional polishing pad; [0012]FIG. 1B is a side cut-away view of a polishing pad having individual polishing elements which may be configured in accordance with embodiments of the present invention; [0013]FIG. 2A is a top view of a polishing pad configured in accordance with an embodiment of the present invention and having polishing elements arranged in circumferences of different radii; [0014]FIG. 2B is a top view of a polishing pad configured in accordance with an embodiment of the present invention and having polishing elements arranged in a grid-like fashion; [0015]FIG. 3 is a top view of a polishing pad configured in accordance with and embodiment of the present invention and showing in detail the use of polishing elements having different coefficients of friction. DETAILED DESCRIPTION [0016]Described herein is a CMP polishing pad which allows for establishing a predefined, non-planar material removal profile. In one embodiment, the pad includes polishing elements, which are placed on an underlying compressible foam and protrude through holes in a guide plate overlaid on that foam. The nominal size of each polishing element is 0.25 inches and the height thereof is 0.160 inches. The compressible foam is nominally 0.060'' thick. [0017]Note that although the present polishing pad is discussed with reference to certain illustrated embodiments, the scope of the present invention is not intended to be limited thereby. Instead, the present invention should only be measured in terms of the claims, which follow this description. [0018]The present pad design enables the application very uniform pressure onto a wafer and eliminates (or at least substantially reduces) edge effect typically associated with full sheet polishing pads. This translates to a very uniform material removal profile. Continue reading... Full patent description for Chemical mechanical polishing pad Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Chemical mechanical polishing pad patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Chemical mechanical polishing pad or other areas of interest. ### Previous Patent Application: Oscillating grinding machine Next Patent Application: Scallop meat separation Industry Class: Abrading ### FreshPatents.com Support Thank you for viewing the Chemical mechanical polishing pad patent info. IP-related news and info Results in 0.80101 seconds Other interesting Feshpatents.com categories: Qualcomm , Schering-Plough , Schlumberger , Seagate , Siemens , Texas Instruments , |
||
