Patent ID: 6727724
Filing Date: 2004-04-27
Classification: G01R,H01L

Abstract:
A characteristic evaluation method for insulated gate type transistors, comprising:a) preparing at least two insulated gate type transistors including first and second insulated gate type transistors that differ from each other only in mask channel width; b) extracting a threshold voltage of said first transistor that has a mask channel width larger than that of said second transistor, estimating a threshold voltage of said second transistor, and employing a value of the estimated threshold voltage as a first estimated value; c) when a difference between a gate voltage of said first transistor and said extracted threshold voltage of said first transistor is defined as a first gate overdrive, a difference between a gate voltage of said second transistor and said first estimated value is defined as a second gate overdrive, (i) under a condition that said first and second gate overdrives are equal in an X-Y plane whose X-axis is said mask channel width and Y-axis is source-drain conductance, extracting a virtual point at which a change in Y coordinate value is estimated to be approximately zero even if said first and second gate overdrives are finely changed, from points on a straight line passing through a first point whose X coordinate is said mask channel width of said first transistor and Y coordinate is said source-drain resistance of said second transistor, and a second point whose X coordinate is said mask channel width of said second transistor and Y coordinate is said source-drain resistance of said first transistor, (ii) defining values of the X coordinate and Y coordinate at said virtual points as second and third estimated values, respectively, and (iii) extracting a slope of said straight line at said virtual points and employing a value of the extracted slope as a fourth estimated value; d) repeating said step c) while varying said first estimated value; e) after said steps c) and d), determining a true threshold voltage of said second transistor by using said first to fourth estimated values; and f) determining a difference between said mask channel width and an effective channel width, based on said true thrreshold voltage.