Up and Down Siliciding Process Patterned by Utilizing a Lift-Off Process
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
A lift-off process is used to pattern silicon over a blanket layer of refractory metal so that self-aligned silicide interconnect regions can be formed in a CMOS transistor. To form a silicide, which is a compound of silicon and a refractory metal, the constituent elements must intermix through an annealing process. When polycrystalline silicon lies above the refractory metal, the silicide is formed by a down-diffusion of the silicon into the refractory metal film. Conversely, when the polysilicon lies below the refractory metal, a silicide is formed by up-diffusion of silicon into the refractory metal film. Here, a lift-off technique is used to define conductive silicide interconnect lines between diffusions without the use of an insulating film or a contact mask. Since the diffusions (i.e.