Plasma etch method for forming uniform linewidth residue free patterned composite silicon containing dielectric layer/silicon stack layer

A method for forming a patterned composite stack layer within a microelectronics fabrication comprising:

• providing a substrate;
• forming a gate oxide layer over the substrate;
• forming over the gate oxide layer a blanket polysilicon layer;
• forming upon the blanket polysilicon layer a blanket first silicon oxide dielectric layer;
• forming upon the blanket first silicon oxide dielectric layer a blanket silicon nitride dielectric layer;
• forming upon the blanket silicon nitride dielectric layer a blanket second silicon oxide dielectric layer;
• forming upon the blanket second silicon oxide dielectric layer a patterned photoresist layer;
• etching sequentially while employing the patterned photoresist layer as a photoresist etching mask layer the blanket second silicon oxide dielectric layer, the blanket silicon nitride layer, the blanket first silicon oxide dielectric layer, and the blanket polysilicon layer while stripping a polymer residue layer formed upon a sidewall of the etched layers and then removing the patterned photoresist mask to form:
• a first patterned composite stack layer comprising a patterned second silicon dielectric layer co-extensive with a patterned silicon nitride dielectric layer in turn co-extensive with a first patterned silicon oxide dielectric layer in turn coextensive with a patterned polysilicon layer, and
• a second patterned composite stack layer comprising another patterned second silicon oxide dielectric layer coextensive with another patterned silicon nitride dielectric layer in turn coextensive with another first silicon oxide dielectric layer in turn coextensive with another patterned polysilicon layer, where the sequential etching is undertaken in situ employing a single plasma reaction chamber and a sequence of etching gas compositions comprising:
• a first etching gas of a perfluorocarbon;
• a second etching gas mixture of a perfluorocarbon and oxygen;
• and
• a third etching gas mixture of chlorine and hydrogen bromide.

A method for forming a patterned composite stack layer within a microelectronics fabrication comprising:

• providing a substrate;
• forming a gate oxide layer over the substrate;
• forming over the gate oxide layer a blanket polysilicon layer;
• forming upon the blanket polysilicon layer a blanket first silicon oxide dielectric layer having a thickness from about 30 to 200 Å;
• forming upon the blanket first silicon oxide dielectric layer a blanket silicon nitride dielectric layer having a thickness from about 200 to 700 Å;
• forming upon the blanket silicon nitride dielectric layer a blanket second silicon oxide dielectric layer having a thickness from about 300 to 900 Å;
• forming upon the blanket second silicon oxide dielectric layer a patterned photoresist layer;
• etching sequentially while employing the patterned photoresist layer as a photoresist etching mask layer the blanket second silicon oxide dielectric layer, the blanket silicon nitride layer, the blanket first silicon oxide dielectric layer, and the blanket polysilicon layer while stripping a polymer residue layer formed upon a sidewall of the etched layers and then removing the patterned photoresist mask to form:
• a first patterned composite stack layer comprising a patterned second silicon dielectric layer co-extensive with a patterned silicon nitride dielectric layer in turn co-extensive with a first patterned silicon oxide dielectric layer in turn coextensive with a patterned polysilicon layer, and
• a second patterned composite stack layer comprising another patterned second silicon oxide dielectric layer coextensive with another patterned silicon nitride dielectric layer in turn coextensive with another first silicon oxide dielectric layer in turn coextensive with another patterned polysilicon layer, where the sequential etching is undertaken in situ employing a single plasma reaction chamber and a sequence of etching gas compositions comprising:
• a first etching gas of a perfluorocarbon;
• a second etching gas mixture of a perfluorocarbon and oxygen;
• and
• a third etching gas mixture of chlorine and hydrogen bromide.

A method for forming a patterned composite stack layer within a microelectronics fabrication comprising:

• providing a substrate;
• forming a gate oxide layer over the substrate;
• forming over the gate oxide layer, a blanket silicon layer;
• forming upon the blanket silicon layer a blanket silicon containing dielectric layer;
• forming upon the blanket silicon containing dielectric layer a patterned photoresist layer;
• then etching the blanket silicon containing dielectric layer while employing a first plasma and the patterned photoresist mask as a first etch mask layer to form a patterned silicon containing dielectric layer having a polymer residue layer formed upon a sidewall of the patterned silicon containing dielectric layer and upon the blanket silicon layer, the first plasma employing a first etchant gas composition comprising a first perfluorocarbon etchant gas;
• then stripping the polymer residue layer from the sidewall of the patterned silicon containing dielectric layer and the surface of the blanket silicon layer while employing a second plasma, the second plasma employing a second etchant gas composition comprising a second perfluorocarbon etchant gas and an oxygen-containing etchant gas;
• then etching the blanket silicon layer and the gate oxide layer to form a patterned silicon layer and patterned gate oxide layer while employing a third plasma and at least the patterned silicon containing dielectric layer without the polymer residue layer as a second etch mask layer;
• and
• then removing the patterned photoresist mask.