Nanometrics Inc.

Robert Buchanan

Richard A Yarussi

Blaine R Spady

John D Heaton

A metrology/inspection system moves the imaging and/or measuring equipment of the system relative to a wafer. Accordingly, measurement or inspection of the wafer does not require that the wafer be mounted on a precision stage. This allows the wafer to be at rest on any structure native in a processing apparatus when the system measures or inspects the wafer. Accordingly, measurement does not require removing the wafer from the processing apparatus and does not delay processing since the wafer can be measured, for example, during a required cool down period of device fabrication process. Alignment of an optical system includes pre-alignment base on edge detection using the optical system and more precise alignment using image recognition. An R-&#x3b8; stage can position the optical system at inspection areas on the wafer. Image rotation can provide a fixed orientation for all images at the various inspection areas and can maintain the fixed orientation when moving from one inspection area to the next.

Metrology/inspection positioning system

A metrology system includes a positioning system that produces linear and rotational motion between an imaging system and the wafer. The imaging system produces signals representing the image of the wafer in the field of view of the imaging system. A control system receives and processes the image signals, and generates corrected signals that compensate for rotational movement between the imaging system and the wafer. In response to the corrected signals, a monitor displays an image with the orientation of features on the wafer within the field of view unaffected by the rotational movement.

Image control in a metrology/inspection positioning system

A method for controlling a polar coordinate stage moves an object relative to an imaging system. While moving the object, the image of the object is rotated to compensate for rotation of the object. Accordingly, the orientations of features in the image are preserved, and removal of apparent rotation in the image reduces confusion an operator experiences while directing movement of the object. The angular velocity of the motion of the object is controlled so that image shift speed is independent of the radial position of the point being viewed. Use of a polar stage, reduces the required foot print for a stage and facilitates prealignment. In particular, an edge detector measures the position of the edge of the object while the polar coordinate stage rotates the object. A prealignment process determines the position and orientation of the object from the measured edge positions. A further alignment process uses automated pattern recognition which more easily identifies features on the object when the image is rotated so that the orientations of the feature are approximately known.

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Pleasanton, CA, United States of America

Robert Buchanan