Kla Instruments Corporation

Kla Instrument Corporation

Paul Sandland

Kenneth Levy

Curt H Chadwick

Russell M Singleton

Howard I Dwyer

Michael L Hodgson

Gerald R Cutler

A system for automatic micro and macro inspection of patterned wafers, including a X-Y stage for supporting and positioning a wafer at a macro inspection station and a micro inspection station, a plurality of cassettes for storing a plurality of patterned wafers before and after inspection, a transfer arm and apparatus for transferring a wafer from the cassettes to a predetermined location on the X-Y stage, apparatus for centering the wafer on the macro inspection station, apparatus for aligning the wafer to obtain a preselected orientation for macro inspection, an optical system for effecting macro inspection of the wafer and storing a unique image thereof, apparatus for moving the wafer from the macro inspection station to the micro inspection station so that the area of the wafer corresponding to the stored unique image is in a micro optical path, autofocus apparatus for automatically focusing the lowest magnification objective lens on the area of the wafer to derive a real time image, a comparitor for comparing the stored unique image to the real time image, apparatus responsive to the comparison of the stored unique image and the real time image and operative to more precisely position the wafer in the micro optical path, apparatus for using areas of the wafer displaced one from the other to obtain more precise alignment of the wafer, apparatus for performing a pre-established micro inspection of selected areas of the wafer and apparatus for returning the wafer to a storage cassette.

Electronic control of an automatic wafer inspection system

An automatic semiconductor wafer inspection system including a wafer inspector, a system computer that performs movement and function control and data storage functions and a high speed image computer. Patterned wafers selected for inspection are automatically transported from cassette storage to a vacuum chuck located on the X-Y stage and positioned in a macro inspection station. The wafer is aligned and the surface illumination is changed to test for macro defects under different lighting conditions and levels of magnification. The reflected light is applied to a camera where the optical image is converted to an electrical representation thereof, stored, and then processed by the high speed image computer. After a wafer has been positioned and inspected in the macro inspection station at low magnification, it is moved by a macro-micro transport arm to the micro inspection station and a unique image previously found in the low power image is found again and used for initial alignment. An autofocus arrangment automatically focusses the objective lens to accomplish the micro inspection tests. Tests are typically carried out at a number of sites, each of which is positioned automatically by the machine.

Method and apparatus for automatic wafer inspection

An automatic patterned wafer inspection system includes macro and micro inspection stations having optical axes that are 10 inches apart on an X-Y crossed roller stage which provides 7 inches of travel in each of two directions along two orthogonal axes. A macro-micro transport arm is pivotally interconnected with the stage and supports a turntable with a vacuum chuck centrally located thereon. The transport arm is positioned to move the wafer from a position 5 inches to the left of center of the stage (the macro axis) to a position 5 inches to the right of the center of the stage (the micro axis). Repeatability of positioning of the arms is obtained by using a spring-loaded link to drive the transport arm against a hard stop located at the left and right of the stage. The turntable is mounted so as to have an outside edge adjacent the distal end of the transport arm. A vacuum chuck for holding the wafer is attached to the turntable. A belt and pulley drive is used to rotate the turntable when it is necessary for the wafer alignment.

X-Y Stage for a patterned wafer automatic inspection system

Optical inspection apparatus for detecting differences between two dies in a photomask and including a carriage for supporting the objects to be inspected and for simultaneously moving such objects along an inspection path, an illuminator for illuminating corresponding portions of the objects as they are moved along the inspection path, electro-optical detectors for individually inspecting the illuminated portions and for developing first and second electrical signals respectively corresponding thereto, electronic memories for storing the first and second electrical signals, a computer for scanning the memories and for electronically aligning a readout of the first signal relative to a readout of the second signal, and a comparator for comparing the electronically aligned signals and for indicating any differences therebetween.

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Gilroy, CA, United States of America

Paul Sandland