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  Methods and systems for determining physical parameters of features on microfeature workpiecesUSPTO Application #: 20060046618Title: Methods and systems for determining physical parameters of features on microfeature workpieces Abstract: Methods and systems for determining physical parameters of features on microfeature workpieces. In one embodiment, a method includes directing a substantially coherent probe beam at a selected area of a feature on the microfeature workpiece to produce a reflected probe beam having phase information of different points within the selected area. The selected area can be only a portion of the workpiece. The method further includes determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam. The physical parameter can be a depth, height, thickness, width, or other dimension of a layer, trench, hole, projection, or other feature on the workpiece. (end of abstract)
Agent: Perkins Coie LLP Patent-sea - Seattle, WA, US Inventors: Gurtej S. Sandhu, Cem Basceri USPTO Applicaton #: 20060046618 - Class: 451006000 (USPTO) Related Patent Categories: Abrading, Precision Device Or Process - Or With Condition Responsive Control, By Optical Sensor The Patent Description & Claims data below is from USPTO Patent Application 20060046618. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to methods and systems for determining physical parameters of features on microfeature workpieces. More particularly, the invention is directed to methods and systems for measuring dimensions, changes in dimensions, planarity, and/or changes in planarity of features on workpieces. BACKGROUND [0002] Deposition, photolithography, etching, and doping are some of the primary processes used in the manufacture of microelectronic devices (e.g., dies) on semiconductor wafers. Microelectronic devices typically include submicron features formed on the wafer with precise dimensions. Errors in process steps can cause many problems including defective microelectronic devices. As such, the efficacy of the manufacturing processes must be qualified to ensure that the devices do not have defects and to determine whether anomalies are occurring in the processes. For example, after depositing a layer of material onto the wafer, the thickness of the layer can be measured to ensure that it is within the specification. [0003] Metrology tools are used to measure various parameters of the wafer at different times during the production process and to ensure that the features formed on the wafer are within specification. One conventional metrology tool includes a laser that directs a small laser beam toward discrete points on the surface of the wafer to measure the distance between the laser and the surface at the individual points. For example, after removing material from the wafer via chemical-mechanical planarization ("CMP"), the planarity of the wafer surface should be checked because CMP processing may remove material from the perimeter region of the wafer at a different rate than from the center region of the wafer. To estimate the edge uniformity of the wafer, conventional metrology tools or other types of optoelectronic tools typically measure the distance between the wafer and the laser at 9 to 13 discrete points around the wafer perimeter. Based on the measurements at these different points, the tool estimates the edge uniformity of the wafer. Conventional systems similarly estimate the planarity of the surface by measuring the distance between the laser and the wafer at 30 to 50 discrete points across the wafer. Although these approaches are useful, the wafer surface may vary between the measured points and, accordingly, the results may not be accurate. [0004] In other applications, metrology tools may estimate the thickness or change in thickness of a film by measuring the distance between the wafer and the laser at 30 to 50 discrete points before and after the film is deposited, etched or planarized. The difference between the before and after measurements corresponds to the thickness of the film or the change in film thickness. One problem with measuring 30 to 50 points before and after processing the wafer is that it is time consuming and reduces throughput. Moreover, the measurements may not provide an accurate representation of the film thickness because of variances across the wafer. Accordingly, there is a need for a fast and accurate process to determine physical features on the wafer. BRIEF DESCRIPTION OF THE DRAWINGS [0005] FIG. 1 is a schematic isometric view of a system for measuring a physical parameter of a feature on a microfeature workpiece in accordance with one embodiment of the invention. [0006] FIG. 2 schematically illustrates a process for scanning the workpiece in accordance with another embodiment of the invention. [0007] FIG. 3 is a schematic side cross-sectional view of the system with an apparatus for measuring a depth of a feature on a workpiece. [0008] FIG. 4 is a schematic side cross-sectional view of a system for determining a change in the thickness of a feature on a workpiece in accordance with another embodiment of the invention. [0009] FIG. 5 is a schematic view of a system for polishing a microfeature workpiece in accordance with another embodiment of the invention. DETAILED DESCRIPTION [0010] A. Overview [0011] The present invention is directed toward methods and systems for determining physical parameters of features on microfeature workpieces. In one embodiment, a method includes directing a substantially coherent probe beam at a selected area having a plurality of regions on the microfeature workpiece to produce a reflected probe beam having phase information of the individual regions within the selected area. The selected area can be only a portion of the workpiece. The method further includes determining a physical parameter of one or more features at the individual regions within the selected area of the workpiece based on the reflected probe beam. The physical parameter can be a depth, height, thickness, width, or other dimension of a layer, trench, hole, projection, or other feature on the workpiece. [0012] In another embodiment, a method includes directing a substantially coherent probe beam toward a selected area of a feature on the microfeature workpiece to produce a first reflected probe beam having phase information of different points within the selected area. The method further includes processing the selected area of the workpiece, impinging the substantially coherent probe beam upon the selected area of the feature to generate a second reflected probe beam having phase information of different points within the selected area, and determining a change in a physical parameter of the feature in the selected area based on the first and second reflected probe beams. Processing the workpiece includes depositing material onto the workpiece and/or removing material from the workpiece. [0013] Another aspect of the invention is directed to methods for polishing microfeature workpieces. In one embodiment, a method includes pressing a microfeature workpiece against a polishing pad, moving the workpiece relative to the polishing pad, and directing a substantially coherent probe beam at a selected area of a feature on the workpiece to produce a reflected probe beam having phase information of different points within the selected area. The method further includes determining a physical parameter of the feature at the different points within the selected area of the workpiece based on the reflected probe beam, and adjusting at least one polishing parameter in response to the determined physical parameter of the feature. [0014] Another aspect of the invention is directed to systems for determining a physical parameter of a feature on a microfeature workpiece. In one embodiment, a system includes a radiation source for producing a substantially coherent probe beam, a sensing device for receiving a reflected probe beam and generating electrical signals based on the reflected probe beam, a workpiece support for positioning the microfeature workpiece in a path of the probe beam, and a controller. The controller has a computer-readable medium containing instructions to perform any one of the above-mentioned methods. [0015] The present invention is directed toward methods and systems for determining physical parameters of features on microfeature workpieces. The term "microfeature workpiece" is used throughout to include substrates in and/or on which microelectronic devices, micromechanical devices, data storage elements, and other features are fabricated. For example, microfeature workpieces can be semiconductor wafers, glass substrates, insulated substrates, or many other types of substrates. Several specific details of the invention are set forth in the following description and in FIGS. 1-5 to provide a thorough understanding of certain embodiments of the invention. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that other embodiments of the invention may be practiced without several of the specific features explained in the following description. B. Embodiments of Systems for Measuring Physical Parameters of Features on Microfeature Workpieces [0016] FIG. 1 is a schematic isometric view of a system 100 for measuring a physical parameter of a feature on a microfeature workpiece 140 in accordance with one embodiment of the invention. The system 100, for example, can measure the depth, thickness, and/or other dimensions or changes in a dimension of a feature on the workpiece 140. This is particularly useful in (a) qualifying workpieces after processing steps to ensure the workpieces are within specification, and (b) providing feedback to processing machines for modifying processing parameters to produce workpieces within specification. [0017] The illustrated system 100 includes a measuring apparatus 110 for directing a coherent optical probe beam 118 along a beam path, a workpiece support 160 for positioning the workpiece 140 in the beam path, and a controller 170 (shown schematically) for operating the measuring apparatus 110 and/or the workpiece support 160. The measuring apparatus 110 includes a radiation source 112 (shown schematically) for producing the coherent probe beam 118, an optical element 113 (shown schematically) for directing the coherent probe beam 118 toward a selected area 142 of the workpiece 140, and a sensing device 114 for receiving a reflected probe beam. The radiation source 112 can be a laser, and the optical element 113 can be a beam splitter. As such, the coherent probe beam 118 impinges a surface 141 of the workpiece 140 at numerous points 143 or regions within the selected area 142 and is reflected back toward the measuring apparatus 110. The reflected probe beam contains phase information of the individual different points within the selected area 142 that corresponds to the profile of the surface 141 within the selected area 142. The reflected probe beam accordingly represents the individual points 143 in a manner generally analogous to discrete pixels. Although the selected area 142 in the illustrated embodiment has a circular shape, in other embodiments, the selected area 142 may have a rectangular, triangular, elliptical, or other shape depending on the configuration of the optical element 113. [0018] In one embodiment, the probe beam 118 impinges the surface 141 of the workpiece 140 at a specific number of discrete points 143 within the selected area 142. Since the number of points 143 is fixed for a given hardware design, the probe beam 118 can be focused and the size of the area 142 can be selected for a desired resolution. For example, the probe beam 118 can be focused on a small area 142 of the surface 141 for a high resolution exposure, or the probe beam 118 can be focused on a larger area 142 of the surface 141 for a lower resolution exposure. In one embodiment, for example, the selected area 142 can be approximately one to two square inches, and the apparatus 110 can measure approximately one million points within the selected area 142 to determine the surface profile within the selected area 142. [0019] The measuring apparatus 110 further includes a sensing device 114 (shown schematically) for receiving the reflected probe beam and producing electrical signals based on the phase information in the reflected probe beam. The electrical signals can be processed by the controller 170 to extract the surface profile information. The sensing device 114 can be a Charge Coupled Device (CCD), Complementary Metal-Oxide Semiconductor (CMOS), or other photosensing medium. The measuring apparatus 110 may also include gratings, lenses, and/or optical members for defracting and/or manipulating the reflected probe beam before the beam reaches the sensing device 114. Suitable measuring apparatuses include the system described in U.S. Pat. No. 6,031,611 entitled "Coherent Gradient Sensing Method and System for Measuring Surface Curvature," which is herein incorporated by reference. Continue reading... Full patent description for Methods and systems for determining physical parameters of features on microfeature workpieces Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Methods and systems for determining physical parameters of features on microfeature workpieces 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. 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