LAMINATED Al-W-Al STRUCTURE
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
This publication describes a laminated structure and process conditions in which thick tungsten film is prepared with good mechanical properties, such as adhesion and stress. Tungsten is a new material in VLSI circuits which has been considered as an etch stop, as a stud material, as a contact diffusion barrier  and for gates and interconnections [1,2,3]. Delineation of tungsten lines or studs can be made by reactive ion etching (RIE). An etch stop is generally required for metal RIE to either avoid or reduce substrate etch, or to protect the uncovered contacts, and Al films are known to be a durable mask in reactive ion etching of W; hence the Al films must also be a good etch stop in W RIE. (That is a thin film of Al under the W acts to stop the etch process.) The figure describes a typical cross-sectional view.