SBIR-STTR Award

The Small Business Innovation Research (SBIR) Phase I project will develop a novel infrared measurement technique for determining the thickness of ultra-thin (0 to 200 microns) and patterned silicon wafers, and the depth of etched features (maximum trench depth of 150 microns) in micro electro-mechanical systems (MEMS). The proposed instrument is a chromatic confocal sensor (spreads a focused spot along the axial direction according to color, or wavelength, of the light) operating in the near infrared spectrum, where silicon is transparent. With the advent of ultra-thin wafers, the present technology of capacitance testing to gage the wafers is no longer adequate. The proposed instrument, therefore, will improve the accuracy of measurements needed in the silicon microelectronics and MEMS industries. This measurement technique also has the potential to reduce the cost of silicon based microelectronics

The Small Business Innovation Research (SBIR) Phase II project will design and construct prototype measurement systems based on near infrared (NIR) chromatic confocal sensor technology. Silicon is transparent in the NIR, and thus the sensor measures the distance to the front and back surfaces of the wafer simultaneously. The sensor will measure deep trenches and vias from the back side so that their aspect ratios are of no consequence. The proposed innovations lie in the sensor design and integration. The proposed measurement systems will address the following semiconductor industry needs: 1) in situ wafer thickness measurement during wafer thinning operations; 2) wafer thickness and shape measurements of ultra-thin wafers; and 3) the measurement of deep, high aspect ratio, etched trenches and vias in silicon. Direct, in situ, measurements during wafer thinning are not currently possible. Neither is the nondestructive measurement of trench depth of many types of deep etched trenches and vias. The measurement of the thickness of ultra-thin wafers (<150 micron) requires greater accuracy for less cost than is currently available. Present technology does not have the resolution for measuring thickness in this thinner range, nor does it have sufficient spatial density on the wafer to accurately describe its shape.