Method for controlling lateral diffusion of silicon in a self-aligned TiSi.sub.2 process

A method for forming a titanium silicide coating on the exposed surface region of a silicon structure, with the upper surface of the silicon structure being divided into an unexposed region overcoated with a first oxide layer and an exposed region not overcoated with the first oxide layer, and with the exposed region of the silicon structure and the upper surface of said first oxide layer being overcoated with a titanium layer, said method comprising the steps of:

• placing said overcoated silicon structure into an airtight chamber;
• providing an ambient atmosphere in said airtight chamber of ultrapure, gaseous nitrogen (N.sub.2);
• and
• sintering said titanium layer by exposing said structure to radiation from a tungsten-halogen source, said radiation being of a predetermined intensity, and said exposure being for a predetermined period of time to form a layer of titanium silicide along the exposed surface of said silicon structure.

A method for forming a titanium silicide coating on the exposed surface region of a silicon structure, with the upper surface of the silicon structure being divided into an unexposed region overcoated with a first oxide layer or a field oxide layer and an exposed region not overcoated with the first oxide layer or field oxide layer, and with the exposed region of the silicon structure and the upper surface of said first oxide layer being overcoated with a titanium layer, said method comprising the steps of:

• placing said overcoated silicon structure in an airtight chamber;
• providing an ambient atmosphere in said airtight chamber of ultrapure, gaseous nitrogen (N.sub.2);
• sintering said titanium layer by exposing said structure to radiation of a predetermined intensity, from a tungsten-halogen source, for a predetermined period of time to form a layer of titanium silicide along the exposed surface of said silicon structure;
• selectively etching titanium from the upper surface of said first oxide layer and said field oxide layer;
• providing an ambient atmosphere of gaseous nitrogen (N.sub.2) including a trace of oxygen (O.sub.2);
• resintering said structure by reexposing the structure to said radiation to increase the conductivity of the titanium silicide layer formed by said first sintering step and to oxidize trace amounts of conductive material on the surface of said oxide layers to reduce leakage from active devices in said polysilicon line.