Method and apparatus for measuring registration between layers of a semiconductor wafer
Patent 4938600 Issued on July 3, 1990. Estimated Expiration Date: 
February 9, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
February 9, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesMethod and apparatus for exposing multi-level registered patterns interchangeably between stations of a multi-station electron-beam array lithography (EBAL) system Multi-layer circuit board inspection system Method and apparatus for automated reading of vernier patterns Patent #: 4742233 InventorAssigneeApplicationNo. 308253 filed on 02/09/1989US Classes:356/401, With registration indicia (e.g., scale)250/491.1, MEANS TO ALIGN OR POSITION AN OBJECT RELATIVE TO A SOURCE OR DETECTOR348/126, Of electronic circuit chip or board356/400With light detector (e.g., photocell)ExaminersPrimary: Evans, F. L.Assistant: Hantis, Karen Paulette Attorney, Agent or FirmInternational ClassG01B 011/00AbstractMethod and apparatus for measuring displacement between layers of a semiconductor wafer wherein systematic errors associated with the measurement system are eliminated. An optical system, including a microscope and a camera, records an image of registration patterns on different layers of the wafer. The image is analyzed to measure displacement between the registration patterns. A first measurement is taken, the wafer is rotated by 180° about the measurement axis, and a second measurement is taken. The actual displacement between layers of the semiconductor wafer is calculated from the first and second measurements. Since the measured displacements change sign when the wafer is rotated and the systematic errors remain constant, systematic errors drop out of the calculated values of actual displacement. System errors can also be calculated for subsequent correction of measured values.Field of SearchMEANS TO ALIGN OR POSITION AN OBJECT RELATIVE TO A SOURCE OR DETECTORWith object being compared and light beam moved relative to each other (e.g., scanning) BY ALIGNMENT IN LATERAL DIRECTION With light detector (e.g., photocell) With registration indicia (e.g., scale) REGISTRATION OR LAYOUT PROCESS OTHER THAN COLOR PROOFING INCLUDING CONTROL FEATURE RESPONSIVE TO A TEST OR MEASUREMENT | |
