Insitu formation of TiSi2/TiN bi-layer structures using self-aligned nitridation treatment on underlying CVD-TiSi2 layer

A method of forming a titanium silicide contact layer on a substrate;

• comprising the steps of:
• a) providing a first insulating layer having a contact opening over a substrate;
• b) simultaneously selectively depositing a silicon layer and an overlying first titanium silicide layer at a first TiCl.sub.4 to Si containing gas flow ratio;
• c) selectively depositing a second titanium silicide layer over said first titanium silicide layer so that said second titanium silicide layer consumes said silicon layer;
• said second titanium silicide layer formed at a second TiCl.sub.4 to Si containing gas flow ratio higher than said first ratio whereby the second TiCl.sub.4 to Si containing gas flow ratio causes said second titanium silicide layer to consume said silicon layer;
• d) selectively depositing a third titanium silicide layer over said second titanium silicide layer at a third TiCl.sub.4 to Si containing gas flow ratio higher than said first ratio and lower than said second ratio and using a chloride containing gas of a material selected from the group consisting of HCl and ClF.sub.3 ;
• said first, second, and third titanium silicide layers forming a titanium silicide contact layer.