A Model for the Etching of Ti and Tin in SC-1 Solutions

The Standard Clean 1 (SC-1), developed by W. Kern and D. Puotinen in 1965 and disclosed in 1970 [1], consists of a mixture of ammonium-hydroxide, hydrogen-peroxide, and water. (SC-1 is also called the Airfmonium-Hydroxide Peroxide Mixture or APM). Originally, this chemical mixture was developed for cleaning silicon wafers and it has proven to be the most efficient particle removing agent found to date. SC-1 can, however, also be used for etching. SC-1 will etch the following materials: SiO 2 , Si 3 N 4 , Si, Ti and TiN. On top of this, SC-1 will grow an oxide on several materials (i.e., bare silicon). In this paper, a quantitative model for the SC-1 solution is presented. The etching of Ti and TiN is shown to be fundamentally different from the etching of SiO 2 . The mixture of Ammonium-hydroxide and Hydrogen Peroxide must be optimized differently for Ti and TiN etching than for the particle removal from Silicon wafers.