METHOD FOR MAKING AN ELECTRICAL CONTACT TO A SILICON SUBSTRATE THROUGH A RELATIVELY THIN LAYER OF SILICON DIOXIDE ON THE SURFACE OF THE SUBSTRATE AND METHOD FOR MAKING A FIELD EFFECT TRANSISTOR

摘要

A buried electrical contact is made to a substrate of monocrystalline silicon through a relatively thin layer of silicon dioxide without causing damage to the relatively thin layer of silicon dioxide. This is accomplished through depositing a thin layer of polycrystalline silicon over the relatively thin layer of silicon dioxide prior to forming the opening in the relatively thin layer of silicon dioxide for the electrical contact to the substrate. After the thin layer of polycrystalline silicon is deposited, an opening is formed therein so that the thin layer of polycrystalline silicon functions as a mask to etch a corresponding opening in the relatively thin layer of silicon dioxide. Then, a layer of polycrystalline silicon is deposited over the exposed surface of the substrate and the thin layer of polycrystalline silicon to form the electrical contact through the opening in the relatively thin layer of silicon dioxide to the substrate.