Lucid Technologies, Inc.

Chapman Instruments, Inc.

John A Teleska

Robert J Hutchison

Edward J Merritt, Jr

Donald Paul McClimans

Dag Lindquist

Silvio P Marchese-Ragona

John E Stephan

Matthew E Seelig

Robert Bryant

A fully automated surface profiling system having a loading chamber and an adjacent measurement chamber containing a phase differential laser optical scanning system and a five-axis positioner having a vacuum chuck for holding and orienting a wafer for surface profile measurement. The positioner can displace a mounted wafer lengthwise and crosswise of the chamber, can rotate the wafer about vertical and horizontal axes through the positioner, and can rotate the wafer about its own axis. Each motion is motor-driven and can be carried out independently of all the others or in compound motion as needed. The positioner can accommodate a series of replaceable chucks for holding wafers of different diameters. The loading chamber has a cassette dock for receiving a cassette containing wafers to be tested, a robotic server, and a prealigner. All operations within the profilometer are controlled by a programmable CPU at a control station. Test results and analysis can be displayed on an onboard monitor or printed out or stored or transmitted. In operation, the robotic server selects a wafer from the cassette, presents the wafer to the prealigner for centering and orientation, and transfers the wafer through a slot into the measurement chamber and installs the wafer on the positioner for measurement. The positioner orients the wafer responsive to program commands from the CPU, and the desired surface profile measurements are made. When all measurements have been completed on a wafer, the robotic server removes the wafer from the positioner, returns it to the cassette, and selects another wafer for testing.

Automated optical surface profile measurement system

In order to digitize with sufficient resolution an analog signal, which may be generated by a photodetector in a spectrophotometer, an improved analog to digital conversion system is provided having an integrator stage, an analog to digital converter, a microprocessor and interface circuits for providing communication between the microprocessor and a host computer. The integrator may include an operational amplifier with a capacitor in feedback relationship therewith for providing an output which varies linearly as function of time. The microprocessor operates the analog to digital converter to sample the integrator output at successive increments of time which increase in accordance with a binary relationship to an increment corresponding in binary value to the desired upper end of the resolution range. The digitized samples from the analog to digital converter are compared with a predetermined value in the upper end of the amplitude range of the converter. Low amplitude analog signals do not reach the predetermined level until the later sampling times and thus are resolved at the upper end of the resolution range. Higher amplitude analog signals are resolved at the lower end of the resolution range. Thus the resolution dynamically and automatically increases inversely with the amplitude of the analog signal being digitized. The digitized value is expressed by two binary numbers, one corresponding to the number of samples until detection of the sample of the integrator output achieving the predetermined amplitude, and the other corresponding to the value which the integrated signal has achieved.

Analog to digital conversion system having automatically and dynamically

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Rochester, NY, United States of America

John A Teleska