Method of creating ultra-small nibble structures during mosfet fabrication

A method of creating a nibble structure using an exhume contact mask, comprising the steps of:

• performing a local oxidation of silicon process on a substrate;
• creating gate oxide regions between field oxide regions;
• depositing a layer of polysilicon over the gate oxide and field oxide regions;
• depositing a first layer of conductive material over said layer of polysilicon;
• depositing a first layer of oxide over said layer of conductive material;
• patterning a layer of photoresist and etching the first oxide, conductive material, and polysilicon layers;
• conducting an implant in an active area of the substrate;
• depositing a layer of nitride;
• patterning a layer of photoresist and etching the nitride and first oxide layers to create an exhume contact opening and an opening over the field oxide;
• depositing a second layer of oxide;
• removing the second layer of oxide so as to leave spacers in the opening over the field oxide and in the exhume contact opening and to leave a remaining exposed nitride;
• removing the remaining exposed nitride;
• performing an implant;
• depositing a second layer of conductive material;
• depositing a third layer of oxide;
• patterning a layer of photoresist and etching the third layer of oxide and the second layer of conductive material;
• and. patterning a layer of photoresist and etching in the opening over the field oxide through the first layer of conductive material and the layer of polysilicon down to the field oxide region to create a nibble structure in the polysilicon layer.

A method of creating a nibble structure using an exhume contact mask, comprising the steps of:

• depositing a layer of nitride;
• patterning a layer of photoresist with an exhume contact mask modified to include a nibble pattern;
• removing a portion of the nitride layer and an underlying oxide layer according to the patterned photoresist to create an exhume contact opening and an opening over the field oxide;
• creating spacers in the opening over the field oxide leaving an exposed portion of the nitride layer;
• removing the exposed portion of the nitride layer;
• and
• removing a conductive layer and a polysilicon layer exposed in the opening over the field oxide down to the field oxide to create a nibble structure in the polysilicon layer.