Reduction of polysilicon contact resistance by nitrogen implantation

A method for reducing polysilicon contact resistance, comprising the steps of:

• providing a first layer of polysilicon, having a surface, on a substrate;
• removing an amount of said surface, thereby exposing a fresh surface;
• before said fresh surface is exposed to air, implanting nitrogen ions, at a voltage and at a dosage, in said fresh surface to a depth;
• and
• depositing a second layer of polysilicon on said implanted surface whereby contact resistance between the layer of polysilicon and said implanted surface is reduced.

A process for forming a self-aligned polysilicon contact in an integrated circuit, comprising the steps of:

• providing a silicon body;
• forming a layer of gate oxide on said silicon body;
• depositing a first layer of polysilicon on the layer of gate oxide;
• patterning and etching said first layer of polysilicon and layer of gate oxide to form a gate electrode;
• forming self-aligned source and drain regions adjacent to the gate electrode;
• depositing a dielectric layer over the gate and the source and drain regions;
• patterning and etching the dielectric layer to form a gate contact window, having a width, thereby exposing a fresh gate surface;
• before said fresh gate surface is exposed to air, implanting nitrogen ions, at a voltage and at a dosage, in said fresh gate surface to a depth;
• and
• depositing a second layer of polysilicon on said dielectric layer and on said implanted gate surface whereby contact resistance between the layer of polysilicon and said implanted surface is reduced.