Methods of forming pairs of transistors, and methods of forming pairs of

Abstract

The invention encompasses methods of forming pairs of transistor gates. In one aspect, the invention includes a method comprising: a) defining a first region and a second region of a substrate; the first region and second region comprising a first substrate surface and a second substrate surface, respectively; b) improving a lifetime of a low voltage tolerant transistor formed proximate the first substrate surface by cleaning the first substrate surface with a first mixture comprising hydrofluoric acid and hydrochloric acid; c) forming a first transistor gate over the first substrate region and incorporating the first transistor gate into the low-voltage tolerant transistor; and d) forming a second transistor gate over the second substrate region and incorporating the second transistor rate into a high-voltage tolerant transistor. In another aspect, the invention includes a method comprising: a) defining a first region and a second region of a substrate; the first region and second region comprising a first substrate surface and a second substrate surface, respectively; b) cleaning at least one of the first and second substrate surfaces with a first mixture comprising hydrofluoric acid and hydrochloric acid; c) after cleaning the at least one of the first and second substrate surfaces, forming a first oxide layer over the first and second substrate surfaces; d) removing the first oxide layer from over the first substrate surface while leaving the first oxide layer over the second substrate surface; and e) forming a second oxide layer over the first substrate surface.