Fabrication of field-effect transistor with vertical body-material dopant profile tailored to alleviate punchthrough and reduce current leakage
First Claim
1. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
- separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material;
subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor;
subsequently introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone below the body'"'"'s upper surface, (e) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, and (f) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type; and
, during or/and subsequent to the act of introducing the dopant of the second conductivity type,annealing the semiconductor body by an annealing procedure comprising subjecting the semiconductor body to an annealing temperature of at least 540°
C.
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Accused Products
Abstract
Fabrication of an insulated-gate field-effect transistor (110) entails separately introducing three body-material dopants, typically through an opening in a mask, into body material (50) of a semiconductor body so as to reach respective maximum dopant concentrations at three different vertical locations in the body material. A gate electrode (74) is subsequently defined after which a pair of source/drain zones (60 and 62), each having a main portion (60M or 80M) and a more lightly doped lateral extension (60E or 62E), are formed in the semiconductor body. An anneal is performed during or subsequent to introduction of semiconductor dopant that defines the source/drain zones. The body material is typically provided with at least one more heavily doped halo pocket portion (100 and 102) along the source/drain zones. The vertical dopant profile resulting from the body-material dopants alleviates punchthrough and reduces current leakage.
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Citations
66 Claims
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1. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; subsequently introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone below the body'"'"'s upper surface, (e) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, and (f) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type; and
, during or/and subsequent to the act of introducing the dopant of the second conductivity type,annealing the semiconductor body by an annealing procedure comprising subjecting the semiconductor body to an annealing temperature of at least 540°
C. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 31, 32, 33, 34, 35)
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16. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; subsequently introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) a channel surface depletion region extends along the body'"'"'s upper surface into the channel zone so as to reach a maximum thickness at a location in the channel zone, (e) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type occurs below the location of the channel surface depletion region at its maximum thickness, (f) each of the two deepest ones of the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone, (g) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, and (h) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type; and
, and, during or/and subsequent to the act of introducing the dopant of the second conductivity type,annealing the semiconductor body by an annealing procedure comprising subjecting the semiconductor body to an annealing temperature of at least 540°
C. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 36, 37, 38, 39, 40)
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41. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; and subsequently introducing (i) semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone and (ii) fourth semiconductor dopant of the first conductivity type into at least the intended channel-zone portion of the body material such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone below the body'"'"'s upper surface, (e) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, (f) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type, and (g) the fourth dopant of the first conductivity type has a dopant concentration which, in the channel zone along the body'"'"'s upper surface, longitudinally reaches a local surface minimum at a location between the source/drain zones. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; and subsequently introducing (i) semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone and (ii) fourth semiconductor dopant of the first conductivity type into at least the intended channel-zone portion of the body material such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) a channel surface depletion region extends along the body'"'"'s upper surface into the channel zone so as to reach a maximum thickness at a location in the channel zone, (e) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type occurs below the location of the channel surface depletion region at its maximum thickness, (f) each of the two deepest ones of the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone, (g) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, (h) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type, and (i) the fourth dopant of the first conductivity type has a dopant concentration which, in the channel zone along the body'"'"'s upper surface, longitudinally reaches a local surface minimum at a location between the source/drain zones. - View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59, 60)
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61. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material through an opening in a mask provided over the semiconductor body such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; and subsequently introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone below the body'"'"'s upper surface, (e) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, and (f) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type. - View Dependent Claims (62, 63)
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64. A method of fabricating a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising:
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separately introducing first, second, and third body-material semiconductor dopants of the first conductivity type into the body material through an opening in a mask provided over the semiconductor body such that the first, second, and third dopants of the first conductivity type reach respective maximum dopant concentrations at respective materially different first, second, and third locations in the body material; subsequently defining a gate electrode above, and vertically separated by gate dielectric material from, a portion of the body material intended to be a channel zone for the transistor; and subsequently introducing semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type laterally separated by the channel zone such that, upon completion of fabrication of the transistor, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) each source/drain zone comprises a main source/drain portion and a more lightly doped source/drain lateral extension laterally continuous with the main source/drain portion, (c) the channel zone is terminated by the lateral extensions along the body'"'"'s upper surface, (d) a channel surface depletion region extends along the body'"'"'s upper surface into the channel zone so as to reach a maximum thickness at a location in the channel zone, (e) the location of the maximum concentration of each of the first, second, and third dopants of the first conductivity type occurs below the location of the channel surface depletion region at its maximum thickness, (f) each of the two deepest ones of the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type extends continuously laterally so as to underlie at least part of each source/drain zone, (g) the body material has a net dopant concentration that reaches three vertically separate local subsurface maxima along an imaginary line that extends generally perpendicular to the body'"'"'s upper surface through the channel zone and into underlying matter of the body material, and (h) the three local subsurface maxima in the net dopant concentration of the body material respectively largely occur along the locations of the maximum concentrations of the first, second, and third dopants of the first conductivity type. - View Dependent Claims (65, 66)
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Specification