Kla Tencor Corporation

Kla-tencor Technologies Corporation

Charles E Wayman

Mehrdad Nikoonahad

Steve R Lange

A technique for focusing and maintaining the focus of an inspection or review system upon a specific layer of a multi-layered specimen is described. In one embodiment, a confocal autofocus system can be used to focus an optical inspection or review system upon the top layer of a semiconductor wafer thin-film stack. The confocal autofocus system utilizes a tilted mask having a linear array of apertures or a continuous slit that is aligned so that a respective linear array of focal points or a focal slit is parallel with a scanning axis of the inspection system. Appropriate processing of the profile depth information yields knowledge of the depth of various layers in the specimen and allows for selection of the layer or location of interest upon which to focus the inspection or review system.

Slit confocal autofocus system

An optical surface inspection system is designed to correct for misregistration errors. A reference vector of data samples is obtained by computing an average of adjacent data sample vectors. A comparison of the data samples in a current vector being processed to data samples that may be offset from such current vector along the direction of the current vector enables the detection and correction of misregistration errors. Alternatively, a target array of data samples is compared to a reference array of data samples collected from a different portion of the surface with various offsets for detection and correction of misregistration errors. The intensity of the reflection from the inspection beam may be monitored to vary the intensity of the inspection beam so as to reduce the dynamic range of background scattering.

Growing community of inventors

San Jose, CA, United States of America

Charles E Wayman