In semiconductor manufacturing, a dimension is considered critical if it impacts final device performance -- for example, very small changes in transistor gate length, width, or sidewall angle can result in significant performance reductions. Measuring critical dimensions with optical scatterometry has become a key process control technology for semiconductor manufacturers at the 90 nm node and below. Rudolph's Focused Beam™ Scatterometry (FBS), based on the simultaneous collection of data at multiple laser wavelengths and multiple angles, brings unique advantages to this application.

The laser light sources offer high speed, accurate, and stable CD measurements and provide the small spot size needed to measure within the scribe line or active die regions of current and future process generations. FBS additionally offers a low cost of ownership, since the multi-angle capability is sensitive to both film thickness and CD, eliminating the need for separate tools for each application. This ability to simultaneously measure film thickness and CD makes FBS ideal for process control of the patterned test structures that manufacturers are increasingly adopting to more closely represent how a process performs on active die.