Philips acquires Active Impuls Systems

12/01/1998

Philips acquires Active Impulse Systems

Philips Analytical, a division of Philips Electronics of the Netherlands, has acquired Active Impulse Systems, Natick, MA, to expand its line of wafer measuring instruments. Active Impulse, founded by a research group from MIT, developed a high-speed, noncontact system for measuring thickness, density, and concentricity of metal films. An instrument has already been installed at the copper bay at SEMATECH in Austin, TX, to measure copper films in both the CVD and CMP process areas.

The instrument can map an entire wafer in about 2 min, for film thicknesses from 100 ? up to 5 ?m, using 625 point measurements with a pair of lasers. A neodymium YAG laser developed at MIT, about 3 in. long and 2 in. in diameter, excites the film with a 600-psec pulse. Rapid heating causes expansion of the top film, which generates ultrasonic waves that propagate through a film stack. A continuous wave laser (AlGaAs/GaAS) allows the interference pattern on the surface to be mapped with refracted light as echoes arrive from each junction between layers. The decay of the signal provides density information.

The measurements are not only faster than other methods, according to John Hanselman, director of semiconductor-USA and general manager of Philips Analytical-Boston, they also can be extended to the edges of wafers. They have measured copper-tantalum stacks at SEMATECH, down to 50 ? thickness, he says, and have been used for tungsten films. The company is offering an Impulse 300 system for $525,000 (manual operation) and $750,000 (fully automated). - B.H.