Abstract: A method of fabricating a microfuse, deletable by laser pulses utilizes laser pulses of a predetermined spot diameter and beam alignment accuracy. A fusible link forming a portion of the microfuse is defined such that its length is at least equal to the sum of the laser spot diameter and the beam alignment accuracy and its width is no greater than half the laser spot diameter. A method of deleting the microfuse by laser pulses is provided where the microfuse has a predetermined composition, length and width having an axis bisecting the width and parallel to the length and is covered with a passivation layer at least 3 .mu.m thick. The method includes adjusting the diameter of the beam of laser light (i) to at least a minimum diameter of W+.DELTA.P.sub.w, where W equals the width of the microfuse fuse link and .DELTA. P.sub.w equals the accuracy of the beam in the direction of W and (ii) to no more than a maximum diameter of L+.DELTA.P.sub.L, where L equals the length of the microfuse fuse link and .DELTA.P.

Abstract: A planar film resistor is trimmable by a laser beam. A pair of electrodes are spaced apart on a substrate and make contact with a film of resistive material disposed therebetween. The resistive material includes a laser produced trim region disposed internally to all boundaries of the resistive material, and extends through the thickness of said film. The trim region has an elongated dimension which is orthogonal to the most direct current path between the electrodes. In a preferred embodiment, the resistive material is covered by a passivating layer and is trimmed after the passivating layer is in place.