Fabrication of multiple field-effect transistor structure having local threshold-adjust doping

Claim 1

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type simultaneously (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone.

Claim 2

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type simultaneously (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone.

Claim 16

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and such that the threshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the threshold channel portion of the first channel zone being of such length that the first channel zone becomes electrically conductive at a lower threshold voltage than the second channel zone during transistor operation.

Claim 17

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and such that the threshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the threshold channel portion of the first channel zone being of such length that the first channel zone becomes electrically conductive at a lower threshold voltage than the second channel zone during transistor operation.

Claim 23

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conducive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such of the main and threshold channel portions of the first channel zone are electrically in series and such that thereshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semniconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the first gate electrode being at least 50% longer than the second gate electrode, a specified minimum feature size characterizing the method, the second gate electrode being of length approximately equal to the minimum feature size.

Claim 24

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conducive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such of the main and threshold channel portions of the first channel zone are electrically in series and such that thereshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semniconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the first gate electrode being at least 50% longer than the second gate electrode, a specified minimum feature size characterizing the method, the second gate electrode being of length approximately equal to the minimum feature size.

Claim 28

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and such that the threshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the first gate electrode being at least 50% longer than the second gate electrode, the threshold channel portion of the first channel zone being set at such a length that the first channel zone becomes electrically conductive at approximately the same threshold voltage as the second channel zone during transistor operation.

Claim 29

A method of fabricating multiple field-effect transistors from a semiconductive body having material of a first conductivity type, the method comprising the steps of: introducing semiconductor dopant of the first conductivity type (a) into part of a first channel zone of the material of the first conductivity type situated outside a main channel portion of the first channel zone to define a threshold channel portion more heavily doped than the main channel portion and (b) into substantially all of a second channel zone of the material of the first conductivity type spaced laterally apart from the first channel zone; subsequently providing first and second gate electrodes respectively above, and insulatingly spaced apart from, the first and second channel zones; and introducing semiconductor dopant of a second conductivity type opposite to the first conductive type (a) into a pair of laterally separated parts of the semiconductive body to define a pair of first source/drain zones of the second conductivity type laterally separated by the first channel zone such that the main and threshold channel portions of the first channel zone are electrically in series and such that the threshold channel portion more heavily doped than the main channel portion adjoins one of the first source/drain zones and (b) into a pair of laterally separated parts of the semiconductive body spaced laterally apart from the first source/drain zones to define a pair of second source/drain zones of the second conductivity type laterally separated by the second channel zone, the first gate electrode being at least 50% longer than the second gate electrode, the threshold channel portion of the first channel zone being set at such a length that the first channel zone becomes electrically conductive at approximately the same threshold voltage as the second channel zone during transistor operation.