Absh.act-In this paper, a study of the variation of the piezoresistive coefficients from several rosettes on the same die, the same wafer, and finally at different doping levels across a number of wafers has been presented. A thorough error analysis of the method of applying a known uniaxial state of stress using a four-point bending (4PB) fixture was completed. A sensor error analysis demonstrated that it is very difficult to determine accurate values for the sum (rI1 TU) using the common

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... ement rosette, particularly in p-type material. However, an empirical equation has been found that provides an estimate for this coefficient. The second piezoresistive coefficient 7r44 can be measured accurately. However, the results presented for 7144 differ from those of previous authors by some 33%. Thus it appears necessary to measure this value for a given wafer lot.