P-channel field-effect transistor with reduced junction capacitance

Claim 2

A structure comprising a p-channel field-effect transistor comprising: a channel zone situated in a semiconductor body having an upper surface; a pair of p-type source/drain zones situated in the semiconductor body along its upper surface and laterally separated by the channel zone, each source/drain zone comprising a main source/drain portion and a more lightly doped lower source/drain portion underlying, and vertically continuous with, the main portion; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone.

Claim 3

A structure as in claim 1 wherein each source/drain zone further includes a lateral source/drain extension more lightly doped than, and laterally continuous with, that source/drain zone's main portion, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 4

A structure as in claim 1 wherein the gate dielectric layer has a thickness of no more than 10 nm.

Claim 5

A structure as in claim 1 wherein the channel zone is of n-type conductivity whereby the transistor is of enhancement-mode type.

Claim 6

A structure as in claim 1 wherein the main and lower source/drain portions comprise boron-doped silicon.

Claim 7

A structure as in claim 1 further including a metal silicide layer extending along each source/drain zone.

Claim 8

A structure as in claim 6 wherein each metal silicide layer has a thickness of 25–35 nm.

Claim 9

A structure as in claim 2 wherein the main and lower source/drain portions and the lateral extensions comprise boron-doped silicon.

Claim 10

A structure as in claim 2 wherein the gate dielectric layer has a thickness of no more than 10 nm.

Claim 11

A structure as in claim 9 wherein the thickness of the gate dielectric layer is at least 2 nm.

Claim 12

A structure as in claim 9 wherein the thickness of the gate dielectric layer is 3–5 mm.

Claim 13

A structure as in claim 2 wherein the channel zone is of n-type conductivity whereby the transistor is of enhancement-mode type.

Claim 14

A structure as in claim 3 wherein the thickness of the gate dielectric layer is at least 2 nm.

Claim 15

A structure as in claim 13 wherein the thickness of the gate dielectric layer is 3–5 mm.

Claim 16

A structure comprising a p-channel field-effect transistor comprising: a channel zone situated in n-type body material of a semiconductor body having an upper surface; a pair of p-type 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, 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, each source/drain zone comprising a main source/drain portion and a more lightly doped lower source/drain portion underlying, and vertically continuous with, the main portion; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone.

Claim 17

A structure comprising a p-channel field-effect transistor comprising: a channel zone situated in n-type body material of a semiconductor body having an upper surface; a pair of p-type 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, 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, each source/drain zone comprising a main source/drain portion and a more lightly doped lower source/drain portion underlying, and vertically continuous with, the main portion; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone.

Claim 18

A structure as in claim 15 wherein the channel zone's net dopant concentration is of an average value that increases with decreasing length of the channel zone when a given amount of semiconductor dopant per unit width of the channel zone causes the channel zone's net dopant concentration to vary along the body's upper surface.

Claim 19

A structure as in claim 15 wherein, relative to the location of the local surface minimum of the channel zone's net dopant concentration, the channel zone's net dopant concentration along the body's upper surface is greater than the local surface minimum at locations closer to both source/drain zones.

Claim 20

A structure as in claim 17 wherein the channel zone's net dopant concentration increases in moving along the body's upper surface from the location of the local surface minimum towards each source/drain zone.

Claim 21

A structure as in claim 18 wherein the local surface minimum in the channel zone's net dopant concentration occurs approximately at a single point along an imaginary line extending longitudinally between the source/drain zones along the body's upper surface.

Claim 22

A structure as in claim 18 wherein the channel zone's net dopant concentration is approximately constant at the local surface minimum along a non-zero portion of an imaginary line extending longitudinally between the source/drain zones along the body's upper surface.

Claim 23

A structure as in claim 17 wherein the local surface minimum of the channel zone's net dopant concentration increases in value with decreasing length of the channel zone when a given amount of semiconductor dopant per unit width of the channel zone causes the channel zone's net dopant concentration to vary along the body's upper surface and when the channel zone is sufficiently short.

Claim 24

A structure as in claim 15 wherein the primary local subsurface maximum of the body material's net dopant concentration occurs 0.15–0.35 μm below the body's upper surface.

Claim 25

A structure as in claim 15 wherein the channel surface depletion region extends to less than 0.1 μm below the body's upper surface.

Claim 26

A structure as in claim 15 wherein the gate dielectric layer has a thickness of 2–10 nm.

Claim 27

A structure as in claim 24 wherein the thickness of the gate dielectric layer is 3–5 nm.

Claim 28

A structure as in claim 15 wherein the main and lower source/drain portions comprise boron-doped silicon.

Claim 29

A structure as in claim 15 wherein each source/drain zone further includes a lateral source/drain extension more lightly doped than, and laterally continuous with, that source/drain zone's main portion, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 30

A structure as in claim 27 wherein the main and lower source/drain portions and the lateral extensions comprise boron-doped silicon.

Claim 31

A structure comprising a p-channel field-effect transistor comprising: a channel zone of n-type body material of a semiconductor body having an upper surface; first and second p-type source/drain zones situated in the semiconductor body along its upper surface and laterally separated by the channel zone, the first source/drain zone comprising a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the first source/drain zone; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone.

Claim 32

A structure comprising a p-channel field-effect transistor comprising: a channel zone of n-type body material of a semiconductor body having an upper surface; first and second p-type source/drain zones situated in the semiconductor body along its upper surface and laterally separated by the channel zone, the first source/drain zone comprising a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the first source/drain zone; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone.

Claim 33

A structure as in claim 29 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 34

A structure as in claim 30 wherein the second source/drain zone further includes a lower portion more lightly doped than, underlying, and vertically continuous with the main portion of the second source/drain zone.

Claim 35

A structure as in claim 29 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 36

A structure as in claim 32 wherein the second source/drain zone comprises a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the second source/drain zone.

Claim 37

A structure as in claim 32 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 38

A structure as in claim 29 wherein a pocket portion of the body material extends along the second source/drain zone so as to encompass part of the channel zone up to the body's upper surface, the pocket portion being more heavily doped than an adjacent part of the channel zone.

Claim 39

A structure as in claim 35 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 40

A structure as in claim 35 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 41

A structure as in claim 37 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 42

A structure as in claim 35 wherein the second source/drain zone comprises a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the second source/drain zone.

Claim 43

A structure as in claim 39 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 44

A structure as in claim 39 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 45

A structure as in claim 41 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 46

A structure as in claim 29 wherein a pocket portion of the body material extends along the first source/drain zone so as to encompass part of the channel zone up to the body's upper surface, the pocket portion being more heavily doped than an adjacent part of the channel zone.

Claim 47

A structure as in claim 43 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 48

A structure as in claim 43 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 49

A structure as in claim 45 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 50

A structure as in claim 43 wherein the second source/drain zone comprises a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the second source/drain zone.

Claim 51

A structure as in claim 47 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 52

A structure as in claim 47 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 53

A structure as in claim 49 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 54

A structure as in claim 43 wherein a further pocket portion of the body material extends along the second source/drain zone so as to encompass part of the channel zone up to the body's upper surface, the further pocket portion being more heavily doped than an adjacent part of the channel zone.

Claim 55

A structure as in claim 51 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 56

A structure as in claim 51 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 57

A structure as in claim 53 wherein the second source/drain zone comprises a main portion and a more lightly doped lateral extension laterally continuous with the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.

Claim 58

A structure as in claim 51 wherein the second source/drain zone comprises a main portion and a more lightly doped lower portion underlying, and vertically continuous with, the main portion of the second source/drain zone.

Claim 59

A structure as in claim 55 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the first source/drain zone and the lateral extension of the second source/drain zone along the body's upper surface.

Claim 60

A structure as in claim 55 wherein the first source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the first source/drain zone, the channel zone being terminated by the second source/drain zone and the lateral extension of the first source/drain zone along the body's upper surface.

Claim 61

A structure as in claim 57 wherein the second source/drain zone further includes a lateral extension more lightly doped than, and laterally continuous with, the main portion of the second source/drain zone, the channel zone being terminated by the lateral extensions along the body's upper surface.