Method for manufacturing multi-thickness gate dielectric layer of semiconductor device

Abstract

In a method for manufacturing a multi-thickness gate dielectric layer of a semiconductor device, a first dielectric layer is formed on a semiconductor substrate. A second dielectric layer is formed using a different dielectric material from the material constituting the first dielectric layer on the first dielectric layer. A portion of the second dielectric layer is selectively removed so as to selectively expose the first dielectric layer under the second dielectric layer. A portion of the exposed first dielectric layer is selectively removed so as to selectively expose the semiconductor substrate under the exposed first dielectric layer. Thereafter, a third dielectric layer having a thinner thickness than the first dielectric layer is formed on the exposed semiconductor substrate. As a result, a gate dielectric layer is formed to include a thick portion formed of the first dielectric layer and remaining second dielectric layer, a medium-thickness portion formed of the remaining first dielectric layer, and a thin portion formed of the third dielectric layer.