All-optical wafer measurement system

12/01/1998

All-optical wafer measurement system

Impulse 300 performs nondestructive multilayer film thickness and uniformity measurements on semiconductor wafers. The system uses lasers to provide noncontact ?-level repeatability on all metal films, including copper, tungsten, and tantalum. Rapid measurements (<2 sec/spot) allow high-resolution, full-wafer mapping in <2 min. The tool is robust, with a compact, maintenance-free, solid-state excitation laser. The system uses impulsive stimulated thermal scattering technology. Picosecond laser pulses excite mild heating in the film surface, resulting in counter-propagating acoustic waves. The acoustic frequency is captured by a second diffracted laser in real time to determine the film thickness. The robust nature of the Impulse 300 makes it highly suitable for fab process control to monitor process excursions, verify usable film diameters, and measure the width of the exclusion zone. The system suits a variety of applications, including full-wafer multilayer mapping, diameter-scan, and edge-profile characterization, as well as high-resolution mapping. Philips Analytical, Almelo, The Netherlands; ph 31/40-278-8620, www.news.philips.com; in USA, ph 508/655-1222.