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System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpieceSystem and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060192949, System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] The present application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/638,529, filed Dec. 19, 2004, currently pending, the entire disclosure of which is incorporated herein by reference. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT [0002] N/A BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to technology for the inspection of a surface or surfaces of a workpiece, such as a semiconductor wafer, chip, or the like. More particularly, it relates to apparatus and methods for inspection of such workpiece surfaces using electromagnetic energy, e.g., light, to scan the surface to obtain characteristics of the surface or other information concerning the surface. [0005] 2. Description of the Related Art [0006] There are a number of applications in which it is desirable or advantageous to inspect a surface or surfaces of a workpiece to obtain information about the characteristics and/or condition of that surface or surfaces. Examples of workpieces amenable to such application would include, for example, bare or unpatterned semiconductor wafers, semiconductor wafers with an applied film or films, patterned wafers, and the like. Characteristics and conditions of the surface that are commonly of interest include surface geometry such as flatness, surface roughness, etc., and/or the presence of defects, such as particles, crystal originated pits ("COPs") and crystalline growths. Given the increasing drive over the years to reduce device size and density, there has been a need for increasing control over surface characteristics or properties at reduced dimensions, and an increasing demand for a reduction in the size of defects, the types of defects that are permissible, etc. Correspondingly, there is an enhanced need for resolution, detection and characterization of small surface characteristics, properties, defects, etc., and an enhanced need for increased measurement sensitivity and classification capability. [0007] In the face of this demand, a number of systems and methods have emerged to provide this capability. One such system, for example, is disclosed in U.S. Pat. No. 5,712,701 (the "'701 patent"), which is assigned to ADE Optical Systems Corporation of Westwood, Mass. The '701 patent discloses a surface inspection system and related methods for inspecting the surface of a workpiece, wherein a beam of laser light is directed to the surface of the workpiece, the light is reflected off the surface, and both scattered and specular light are collected to obtain information about the surface. An acousto-optical deflector is used to scan the beam as the wafer is moved, for example, by combined rotation and translation, so that the entire surface of the workpiece is inspected. [0008] As our understanding of the physics and phenomenology of optical scattering from surfaces has improved, a capability has been developed and refined in which detailed and high resolution information about defects on the surface can be ascertained. These phenomena largely are obtained from the optical energy that is scattered by the surface, as opposed to the energy in the main reflected beam or the "specular beam." Examples of systems and methods that provide such defect detection capability include that of the '701 patent, as well as U.S. Pat. No. 6,118,525 and U.S. Pat. No. 6,292,259, all of which are assigned to ADE Optical Systems Corporation and all of which are herein incorporated by reference. Systems designed according to these patents have performed admirably and provided major advances over their predecessors. As the drive to smaller device dimensions and higher device densities has continued, however, the need also has continued for the ability to resolve and classify even smaller and smaller surface properties, defects, etc. A need also has developed to detect and characterize a greater range of surface characteristics and defects in terms of the types of defects, their extent or range, etc. Surface scratches are an example. Scratches on the surface of a workpiece often do not lie along a straight line. Surface scratches on semiconductor wafer surfaces, for example, can be the result of polishing, which can leave circular, curved or irregular scratch geometry. As the workpiece surface is moved relative to the beam, the orientation of the scratch relative to the oblique incident beam and collectors changes. This often causes changes in the amplitude and direction of scattered light from the scratch as the wafer rotates. As device dimensions decrease, the ability to detect and characterize the scratches and similar defects with improved sensitivity and reliability has become increasingly important. [0009] Systems that are amenable to inspection and measurement of extremely small dimensions typically must operate in extremely clean environments. This commonly requires that they be contained and operated within a clean room. This highly controlled environment limits normal access to such machines and systems, which increases the difficulty and expense of their maintenance and repair. Accordingly, systems and methods are needed that are amenable to more efficient and effective replacement of precision-aligned optical sub-components within the machines. OBJECTS OF THE INVENTION [0010] Accordingly, an object of the present invention according to one aspect is to provide apparatus and methods for inspecting a surface of a workpiece with high sensitivity and reliability, e.g., for surface defects. [0011] Another object of the invention according to another aspect is to provide apparatus and methods for inspecting a surface of a workpiece that enable an improved range of detection for surface characteristics, such as defects, defect type, etc., relative to known systems and methods. [0012] Another object of the invention according to another aspect is to provide apparatus and methods for inspecting a surface of a workpiece that are accessible and/or amenable to efficient maintenance, repair, upgrade, and the like. [0013] Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations pointed out in the appended claims. SUMMARY OF THE INVENTION [0014] To achieve the foregoing objects, and in accordance with the purposes of the invention as embodied and broadly described in this document, a surface inspection system is provided for inspecting the surface of a workpiece. The surface inspection system comprises a base, a beam source subsystem, a beam scanning subsystem, a workpiece movement subsystem, an optical collection and detection subsystem, and a processing subsystem. The beam source subsystem comprises a beam source that projects an incident beam toward the surface of the workpiece. The beam scanning subsystem comprises means for receiving the incident beam and scanning the incident beam on the surface of the workpiece. The workpiece movement subsystem moves the surface of the workpiece relative to the incident beam. The optical collection and 5 detection subsystem collects portions of the incident beam that are reflected or scattered from the surface of the workpiece and generates signals in response to the reflected portions of the incident beam. The processing subsystem is operatively coupled to the collection and detection subsystem for processing the signals. [0015] Optionally but preferably, the beam source module comprises a beam source housing for fixedly supporting the beam source, and a beam source mounting means for fixedly mounting the beam source housing relative to the base so that the incident beam is projected at a pointing angle to a pointing position that is within about 50 micro radians of a target spot corresponding to a desired spot on the surface of the workpiece. In addition, again optionally but preferably, the beam source module further comprises means for pre-aligning the incident beam to the pointing angle and the pointing position. In a presently preferred embodiment, the beam source housing mounting means comprises a plurality of pinholes and the beam scanning mounting means comprises a corresponding plurality of pins that mate with the plurality of pinholes. In another, the beam source housing mounting means comprises a plurality of pins and the beam scanning mounting means comprises a corresponding plurality of pinholes that mate with the plurality of pins. The beam source housing also may comprise a plurality of pinholes, and the beam scanning mounting means may comprise a corresponding plurality of pins that mate with the plurality of pinholes. [0016] The beam scanning module preferably comprises a beam scanning module housing for supporting the beam scanning means, and beam scanning mounting means for fixedly mounting the beam scanning module housing relative to the base so that the beam is projected to a pointing position that is within about 50 micro radians of a target spot corresponding to a desired spot on the surface of the workpiece. The beam scanning module also preferably comprises means for pre-aligning the incident beam to the pointing position. In a presently preferred embodiment, the base comprises a plurality of pinholes and the beam scanning mounting means comprises a corresponding plurality of pins that mate with the plurality of pinholes. In another embodiment, the base comprises a plurality of pins and the beam scanning mounting means comprises a corresponding plurality of pinholes that mate with the plurality of pins. [0017] The optical collection and detection module preferably comprises a collection and detection module housing for supporting the optical collection and detection module, and collection and detection module mounting means for fixedly mounting the collection and detection module to the base. In a presently preferred embodiment, the base comprises a plurality of pinholes and the collection and detection module mounting means comprises a corresponding plurality of pins that mate with the plurality of pinholes. In another, the base comprises a plurality of pins and the collection and detection module mounting means comprises a corresponding plurality of pinholes that mate with the plurality of pins. [0018] The collection and detection module, also known as collector detector module, preferably comprises at least one, and preferably two, wing collectors positioned to collect the portions of the incident beam that are scattered from the surface of the workpiece. The wing collector or wing collectors are disposed in a front quartersphere, outside an incident plane defined by the incident beam and a light channel axis, and at or near a maximum of the signal to noise ratio. According to another aspect, the wing collector or wing collectors are positioned in null, or a local minimum, in surface roughness scatter relative to defect scatter, for example, from a defect perspective, at a maximum in the signal to noise ratio of defect scatter to surface roughness scatter when the incident beam is P polarized, or, from a surface roughness scatter perspective, when the surface roughness is at a relative minimum in a bi-directional reflectance distribution function when the incident beam is P polarized. [0019] In accordance with another aspect of the invention, a method is provided for assembling a surface inspection system having a base. The method comprises providing the base to include a first mating device, providing a beam source subsystem having a beam source that projects an incident beam and a beam source housing having a second mating device, wherein the beam source is mounted to the beam source housing, pre-aligning the beam source relative to the beam source housing prior to placement of the beam source housing on the base so that the incident beam is projected at a pointing angle to a pointing position that is within about 50 micro radians of a target spot corresponding to a desired spot on the surface of the workpiece, and positioning the beam source housing on the base using the first and second mating devices, whereby the first and second mating devices automatically cause the incident beam to be in the pointing position. Continue reading about System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece... Full patent description for System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece 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 System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece or other areas of interest. ### Previous Patent Application: Inspection of transparent substrates for defects Next Patent Application: System and method for inspecting a workpiece surface using combinations of light collectors Industry Class: Optics: measuring and testing ### FreshPatents.com Support Thank you for viewing the System and method for inspecting a workpiece surface by analyzing scattered light in a back quartersphere region above the workpiece patent info. IP-related news and info Results in 0.29665 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , 174 |
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