University and small firm collaboration for process development of advanced gate dielectrics

The research focus of this paper is the result of collaborations between NC State University and Four Dimensions, Inc. As a result of this partnership, the challenge of probing a patterned wafer with a Hg-probe system that was engineered by Four Dimensions to probe unpatterned wafers emerged. To address this challenge, a novel mask was designed, fabricated, and used to obtain patterned arrays of field-oxide isolated gate oxides as well as so-called “L” strips of gate oxide. Mercury-gate capacitance-voltage measurements from three sites (i.e., unpatterned gate oxides and field oxides plus gate oxides as well as patterned field oxides/gate oxides) were used to validate a relatively simple algorithm for the extraction of oxide thickness. In addition, optical oxide thickness was extracted from the “L” strips, and excellent agreement with the electrical value is demonstrated. This “single wafer” methodology for extracting electrical and optical metrics will have a significant impact on process development of advanced gate dielectrics within the SRC/SEMATECH Center for Front End Processes