A diffused field effect current limiter

Following the development of the cut channel field effect current limiter by Warner, et al. an all-diffused device was designed and fabricated. This paper describes the design parameters as well as the critical fabrication procedures and control limits that were found necessary in order to prepare satisfactory devices. The current limiters were prepared from 3-mil thick slices of 50 ohm-cm, n-type silicon into which 1-mil thick gates were diffused. It is evident from the data that the tolerances for reproducibility of electrical characteristics fall within the expected variations due to diffusion control and parallel polishing of the sample if the background resistivity remains constant. However, because of the many thermal processing steps required in the fabrication procedure, variations occur in the effective impurity content in the high resistivity material. It is seen that the dependence of the electrical behavior of the devices on these variations is critical.