Field-effect transistor for alleviating short-channel effects
AssigneeNational Semiconductor Corporation
InventorsConstantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
Life of this patent
Estimating the term…
Abstract
An IGFET (40 or 42) has a channel zone (64 or 84) situated in body material (50). Short-channel threshold voltage roll-off and punchthrough are alleviated by arranging for the net dopant concentration in the channel zone to longitudinally reach a local surface minimum at a location between the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging for the net dopant concentration in the body material to reach a local subsurface maximum more than 0.1 μm deep into the body material but not more than 0.4 μm deep into the body material.
Claims84
A structure comprising a principal field-effect transistor comprising:
- a channel zone of body material of a semiconductor body having an upper surface, the body material being of a first conductivity type;
- a pair of source/drain zones situated in the semiconductor body along its upper surface, laterally separated by the channel zone, and being of a second conductivity type opposite to the first conductivity type so as to form respective pn junctions with the body material, the channel zone having a net dopant concentration that longitudinally reaches a local surface minimum along the body's upper surface at a location between the source/drain zones, a channel surface depletion region extending along the body's upper surface into the channel zone, the body material having a net dopant concentration that reaches a primary local subsurface maximum below the channel surface depletion region, the primary local subsurface maximum occurring more than 0.1 μm below the body's upper surface but not more than 0.4 μm below the body's upper surface;
- a gate dielectric layer overlying the channel zone;
- and
- a gate electrode overlying the gate dielectric layer above the channel zone.
A structure comprising a pair of like-polarity field-effect transistors provided along an upper surface of a semiconductor body having body material of a first conductivity type, each transistor comprising:
- a channel zone of the body material;
- a pair of source/drain zones situated in the semiconductor body along its upper surface, laterally separated by the channel zone, and being of a second conductivity type opposite to the first conductivity type so as to form respective pn junctions with the body material, the channel zone having a net dopant concentration that longitudinally reaches a local surface minimum along the body's upper surface at a location between the source/drain zones, the body material having a net dopant concentration that reaches a primary local subsurface maximum more than 0.1 μm below the body's upper surface but not more than 0.4 μm below the body's upper surface;
- a gate dielectric layer overlying the channel zone;
- and
- a gate electrode overlying the gate dielectric layer above the channel zone, the channel zones of the two transistors being of sufficiently different channel length that the transistors differ significantly in threshold voltage.
A structure comprising a pair of like-polarity field-effect transistors provided along an upper surface of a semiconductor body having body material, each transistor comprising:
- a channel zone of the body material;
- a pair of source/drain zones situated in the semiconductor body along its upper surface, laterally separated by the channel zone, and forming respective pn junctions with the body material, the channel zone having a net dopant concentration that longitudinally reaches a local surface minimum along the body's upper surface at a location between the source/drain zones, the body material having a net dopant concentration that reaches a primary local subsurface maximum more than 0.1 μm below the body's upper surface but not more than 0.4 μm below the body's upper surface;
- a gate dielectric layer overlying the channel zone;
- and
- a gate electrode overlying the gate dielectric layer above the channel zone, the channel zones of the two transistors being of sufficiently different channel length that the transistors differ significantly in threshold voltage.
Dependencies are inferred from the claim text.