Enhancement in semiconductor wafer metrology will strengthen the U.S. leadership in the production of overlay-metrology tools and indirectly help maintain the nation's number one position in the multibillion dollar global semiconductor industry. The consortium provides domestic companies access to essential technology resources and to results significantly earlier than publication or other conventional means of dissemination would make them available worldwide, including to foreign competitors. The new stage doubles the viewing range of the typical SEM stage and increases the tilt to better than 90 degrees from the horizontal, as compared to the current 60 degrees. Such improved performance capabilities are expected to increase the utility of SEMs as measurement and research tools. NIST scientists have made measurements of the index of refraction of fused silica and calcium fluoride at wavelengths near 193 nanometers.
Engineers require such precise data to design accurately components for the photolithographic tools.
To make the index of refraction measurement accurate to 10 parts in a million, the researchers upgraded a precision refractometer, which is capable of temperature control of 0.1 degrees Celsius. For the longer term and for shorter wavelengths, they are developing interferometric methods capable of higher accuracy. The resistivity of silicon wafers is a vital concern to the multibillion dollar semiconductor industry. This summer, NIST will release five new Standard Reference Materials that will enable manufacturers to calibrate resistivity test instruments to 0.3 percent, or better, with 95 percent confidence. This advance, an improvement over previous resistivity SRMs, cuts resistivity measurement uncertainty by approximately a factor of five.