Method of making a transistor, in particular spacers of the transistor

摘要

The invention provides a method of making a transistor. A gate dielectric layer is formed on a semiconductor substrate. A gate is formed on the dielectric layer, the gate having an exposed upper surface and exposed side surfaces. A first silicon nitride layer having a first thickness is deposited over the gate, for example over an oxide layer on the gate, at a first deposition rate. A second silicon nitride layer having a second thickness is deposited over the first silicon nitride layer at a second deposition rate, the second thickness being more that the first thickness and the second deposition rate being more than the first deposition rate. The first silicon nitrogen layer then has a lower hydrogen concentration. At least the second silicon nitride layer (or a silicon oxide layer in the case of an ONO spacer) is etched to leave spacers next to the side surfaces while exposing the upper surface of the gate and areas of the substrate outside the spacers.