US 6,746,924 B1 · Method of forming asymmetric extension mosfet using a drain side spacer

Abstract

A method of forming an asymmetric extension MOSFET using a drain side spacer which allows a choice of source and drain sides for each individual MOSFET device and also allows an independent design or tuning of the source and drain extension implant dose as well as its spacing from the gate. A photoresist mask is formed over at least a portion of each drain region, followed by an angled ion implant during which the photoresist mask and the gate conductor shield the nitride layer over at least a portion of the drain region and at least one sidewall of the gate conductor from damage by the angled ion implant which selectively damages portions of the nitride layer unprotected by the photoresist mask and the gate conductor. Then damaged portions of the nitride layer are removed while leaving undamaged portions of the nitride layer as a nitride mask to protect at least a portion of each drain region and at least one gate sidewall from a subsequent dopant implant, which is performed into the source regions and the drain regions while using the undamaged portions of the nitride layer as a mask to form the asymmetric extension MOSFET device. In some embodiments the nitride mask can be etched to form drain side spacers to provide different spacings for the source and drain extension ion implants.

Claims13

Dependent claims

A method of fabricating an asymmetric extension MOSFET device using a drain side spacer comprising:

forming a semiconductor device having a substrate on which a gate conductor having sidewalls separates a source region and a drain region, and having an oxide layer formed over the gate conductor, the source region and the drain region, and a nitride layer formed over the oxide layer;
forming a photoresist mask over at least a portion of the drain region;
performing an angled ion implant during which the photoresist mask and the gate conductor shield the nitride layer over at least a portion of the drain region and on at least one sidewall of the gate conductor from damage by the angled ion implant, such that the angled ion implant selectively damages portions of the nitride layer unprotected by the photoresist mask and the gate conductor to form damaged portions of the nitride layer;
removing the damaged portions of the nitride layer while leaving the undamaged portions of the nitride layer as a nitride mask to protect at least a portion of the drain region and at least one gate sidewall from a subsequent dopant implant;
and
performing at least one dopant implant into the source region and the drain region while using the undamaged portions of the nitride layer as a mask to form the asymmetric extension MOSFET device.

3 more elements

A method of fabricating an asymmetric extension stacked MOSFET device using a drain side spacer comprising:

forming a semiconductor device having a substrate having a plurality of spaced gate conductors, with each gate conductor having two sidewalls and separating a source region and a drain region, and having an oxide layer formed over the gate conductors, the source regions and the drain regions, and a nitride layer formed over the oxide layer;
forming a photoresist mask over at least a portion of each drain region;
performing an angled ion implant during which the photoresist masks and the gate conductors shield the nitride layer over at least a portion of each drain region and at least one sidewall of each gate conductor from damage by the angled ion implant, such that the angled ion implant selectively damages portions of the nitride layer unprotected by the photoresist masks and the gate conductors to form damaged portions of the nitride layer;
removing the damaged portions of the nitride layer while leaving the undamaged portions of the nitride layer as a nitride mask to protect at least a portion of each drain region and at least one gate sidewall of each gate conductor from a subsequent dopant implant;
and
performing at least one dopant implant into the source regions and the drain regions while using the undamaged portions of the nitride layer as a mask to form the asymmetric extension stacked MOSFET device.

3 more elements

Dependencies are inferred from the claim text.

Method of forming asymmetric extension mosfet using a drain side spacer

Life of this patent

Method of forming asymmetric extension mosfet using a drain side spacer

Life of this patent

Abstract

Claims13