Method for forming borderless gate structures and apparatus formed thereby

A method for forming a semiconductor device comprising the steps of:

• forming a polysilicon portion of a gate conductor on a substrate having areas surrounding the gate conductor;
• doping the polysilicon portion;
• doping a plurality of diffusion areas in the surrounding areas;
• providing an atmosphere comprising nitrogen;
• irradiating the gate conductor, the irradiating causing relatively high heating of the polysilicon portion and relatively low heating of the surrounding areas such that a silicon nitride cap is formed over the polysilicon portion while the silicon nitride cap is not formed over the surrounding areas;
• and
• forming borderless contacts to the diffusion areas.

A method for forming a transistor having a gate conductor cap comprising the steps of:

• forming a polysilicon portion of a gate conductor on a substrate having areas surrounding the gate conductor;
• doping the polysilicon portion;
• doping a plurality of diffusion areas in the surrounding areas;
• providing an atmosphere containing ammonia and silane;
• and
• exposing the gate conductor to 10-1000 expose pulses of laser irradiation with an energy fluence of 100-500 mJ/cm2 in the presence of a 10:1 volumetric ratio of ammonia and silane, respectively, at a pressure of 0.1-760 torr, thereby causing selective nitride deposition.

A method for forming a transistor having a gate conductor cap comprising the steps of:

• forming a polysilicon portion of a gate conductor on a substrate having areas surrounding the gate conductor;
• doping the polysilicon portion;
• doping a plurality of diffusion areas in the surrounding areas;
• providing an atmosphere containing ammonia;
• and
• exposing the gate conductor to 100-2000 expose pulses of laser irradiation with an energy fluence of 200-700 mJ/cm2 in the presence of ammonia at a pressure of 10-1500 torr, thereby causing selective surface nitridation.