Reliable Tungsten Chemical Vapor Deposition Process With Sputter Etch to Form Contact Studs
Original Publication Date: 1988-Mar-01
Included in the Prior Art Database: 2005-Feb-14
This article relates to an efficient method for eliminating vertical cuts on the side walls of contact holes during an etch back process where a stack of tungsten silicide (WSix)/tungsten (W) is used to form the semiconductor contact studs. Voids in the chemical vapor deposition (CVD) of a tungsten contact stud is also minimized or eliminated by the new method. A film of either sputtered titanium or in-situ tungsten silicide is used as an adhesion film on a boron phosphorus silicon glass (BPSG) substrate when CVD of tungsten is used to produce a W stud. When a WSix stack is used with an etch back process to form the contact stud, severe WSix vertical cuts on the side wall of the contact hole are observed, as shown in Fig. 1a. A void formation problem also exists where 90-degree slope contact holes are used, as shown in Fig. 1b.