n&k Technology Solves Problem of Optically Measuring Pelliclized Photomasks

SANTA CLARA, Calif., January 25, 2006 - n&k Technology, Inc., a manufacturer of advanced metrology equipment, announced that it has solved the problem of making accurate optical measurements on photomasks through attached pellicles. n&k’s solution involves a comparative baseline technique (patent pending) that relates simultaneous reflectance (R) and transmittance (T) measurements of known and unknown samples to eliminate the effects of the pellicle on the raw data. This innovative approach allows n&k’s existing methodology to be implemented as if the pellicle were not present.

Suppliers of photomasks typically place a pellicle, which is a framed membrane, over the mask to protect it after the final step in the mask-making process. At this point, it is desirable to measure mask properties such as trench depth, CD, and profile, as well as film thickness, values of n and k, and phase-shift of materials (for example, MoSiON) deposited on the masks without removing the pellicle. Previously, taking such measurements through a pellicle resulted in significantly altered raw data. With n&k’s new technique, accurate measurements can be obtained optically with the pellicle in place.

n&k Technology’s optical "RT" systems, such as the recently announced n&k 5700-CDRT, are based on simultaneous measurement of R and T, and are already used to measure the above mentioned properties of photomasks without pellicles, in a single step. However, such optical measurements of R and T through a pellicle produce a myriad of interference fringes that complicate the analysis. The comparative baseline technique employed by n&k solves the problem of optically measuring pelliclized photomasks.

"This new measurement solution for pelliclized photomasks is now offered as an option with the n&k 5700-CDRT," stated Dr. Rahim Forouhi, CEO and president of n&k. "Several orders have already been placed by semiconductor companies with captive mask shops," he added. Delivery will begin in the third quarter 2006.

About n&k Technology, Inc.
n&k Technology, Inc., Santa Clara, California, manufactures advanced metrology tools for the semiconductor, photomask, flat panel display, and data storage industries. The company's high-resolution optical metrology equipment is used for film thickness, n and k, phase shift, trench depth, CD, and profile measurements. The company's core technology is based on DUV-Vis-NIR broadband spectrophotometry with patented reflective optics, in conjunction with the Forouhi-Bloomer dispersion equations and Rigorous Coupled Wave Analysis. n&k Technology's equipment, ranging from table-top to fully automated systems, is field-proven, production-worthy, fast, accurate, and non-destructive, enabling users to characterize virtually any combination of thin films, substrates, and structures.