A method of making a semiconductor device includes a substrate having a semiconductor layer having a first portion for non-volatile memory and a second portion exclusive of the first portion. A sensor which measures changes in the direction of the magnetic flux generated by the magnet in response to rotation of the shaft and a pair of magnet pole pieces are located opposite and spaced from the magnet. 5 ppm vanadium by weight, less than 1 ppm sodium and potassium combined by weight, and greater than about 25 ppm ash by weight or greater than 2 ppm calcium by weight.