Self-Aligned Technique Employing Planarized Resist for Reducing Poly-Silicon Sheet Resistance by Formation of a Metal Silicide
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
Utilizing existing CMOS (complementary metal-oxide-semiconductor technologies, a process that includes a combination of self-planarizing materials with separate self-aligned silicide (salicide) formations on gates and diffusions that allows for independent sheet resistance (Rs) optimization without an additional mask level is described. Currently, polysilicon resistance is reduced by the use of silicides. It is difficult to optimize shallow junction contact resistance without some degree of compromise. Circuit performance improvements can be realized by utilizing a novel approach allowing flexibility in the choice of metals for silicide formation on polysilicon gates and shallow junctions of a field-effect transistor. Fig. 1 shows a standard CMOS device structure before metal silicide is used to reduce the sheet resistance.