Abstract:
At least one source/drain zone (140, 142, 160, or 162) of an enhancement-mode insulated-gate field-effect transistor (120 or 122) is provided with graded junction characteristics to reduce junction capacitance, thereby increasing switching speed. Each graded junction source/drain zone contains a main portion (140M, 142M, 160M, or 162M) and a more lightly doped lower portion (140L, 142L, 160L, or 162L) underlying, and vertically continuous with, the main portion. The magnitudes of the threshold voltages of a group of such transistors fabricated under the same post-layout fabrication process conditions so as to be of different channel lengths reach a maximum absolute value VTAM when the channel length is at a value LC, are at least 0.03 volt less than VTAM when the channel length is approximately 0.3 μm greater than LC, and materially decrease with increasing channel length when the channel length is approximately 1.0 μm greater than LC.
Abstract:
An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 220, 220U, 220V, 220W, 380, or 480) has a hypoabrupt vertical dopant profile below one (104 or 264) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108 or 268). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone. The body material preferably includes a more heavily doped pocket portion (120 or 280) situated along the other source/drain zone (102 or 262). The combination of the hypoabrupt vertical dopant profile below the first-mentioned source/drain zone, normally serving as the drain, and the pocket portion along the second-mentioned source/drain zone, normally serving as the source, enables the resultant asymmetric transistor to be especially suitable for high-speed analog applications.
Abstract:
An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 220, 220U, 220V, 220W, 380, or 480) is fabricated so as to have a hypoabrupt vertical dopant profile below one (104 or 264) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108 or 268). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone. The body material is preferably provided with a more heavily doped pocket portion (120 or 280) situated along the other source/drain zone (102 or 262). The combination of the hypoabrupt vertical dopant profile below the first-mentioned source/drain zone, normally serving as the drain, and the pocket portion along the second-mentioned source/drain zone, normally serving as the source, enables the resultant asymmetric transistor to be especially suitable for high-speed analog applications.
Abstract:
An asymmetric insulated-gate field effect transistor (100U or 102U) provided along an upper surface of a semiconductor body contains first and second source/drain zones (240 and 242 or 280 and 282) laterally separated by a channel zone (244 or 284) of the transistor's body material. A gate electrode (262 or 302) overlies a gate dielectric layer (260 or 300) above the channel zone. A pocket portion (250 or 290) of the body material more heavily doped than laterally adjacent material of the body material extends along largely only the first of the S/D zones and into the channel zone. The vertical dopant profile of the pocket portion is tailored to reach a plurality of local maxima (316-1-316-3) at respective locations (PH-1-PH-3) spaced apart from one another. The tailoring is typically implemented so that the vertical dopant profile of the pocket portion is relatively flat near the upper semiconductor surface. As a result, the transistor has reduced leakage current.
Abstract:
Each of a pair of differently configured like-polarity insulated-gate field-effect transistors (40 or 42 and 240 or 242) in a semiconductor structure has a channel zone of semiconductor body material, a gate dielectric layer overlying the channel zone, and a gate electrode overlying the gate dielectric layer. For each transistor, the net dopant concentration of the body material reaches multiple local subsurface maxima below a channel surface depletion region and below largely all gate-electrode material overlying the channel zone. The transistors have source/drain zones (60 or 80) of opposite conductivity type to, and halo pocket portions of the same conductivity type as, the body material. One pocket portion (100/102 or 104) extends along both source/drain zones of one of the transistors. Another pocket portion (244 or 246) extends largely along only one of the source/drain zones of the other transistor so that it is asymmetrical.
Abstract:
A semiconductor junction varactor utilizes gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance.
Abstract:
Complementary IGFETs (210W and 220W or 530 and 540) are fabricated so that the body dopant concentration in each IGFET decreases by at least 10 in moving from a subsurface location in the body material of that IGFET up to one of its source/drain zones. Semiconductor dopant, typically a fast-diffusing species such as aluminum, is introduced into starting semiconductor material to form a relatively uniformly doped region that serves as body material (108) for one of the IGFETs. A remaining part of the starting material serves as body material (268) for the other IGFET. Well dopant is introduced into the body material of each IGFET for establishing the requisite body dopant profile. Alternatively, a cavity is formed through an initial structure having body material (108) doped in the preceding way for one of the IGFETs. Semiconductor material is introduced into the cavity to form the body material (568) for the other IGFET.
Abstract:
An asymmetric insulated-gate field effect transistor (100U or 102U) provided along an upper surface of a semiconductor body contains first and second source/drain zones (240 and 242 or 280 and 282) laterally separated by a channel zone (244 or 284) of the transistor's body material. A gate electrode (262 or 302) overlies a gate dielectric layer (260 or 300) above the channel zone. A pocket portion (250 or 290) of the body material more heavily doped than laterally adjacent material of the body material extends along largely only the first of the S/D zones and into the channel zone. The vertical dopant profile of the pocket portion is tailored to reach a plurality of local maxima (316-1-316-3) at respective locations (PH-1-PH-3) spaced apart from one another. The tailoring is typically implemented so that the vertical dopant profile of the pocket portion is relatively flat near the upper semiconductor surface. As a result, the transistor has reduced leakage current.
Abstract:
A semiconductor structure contains a bipolar transistor (101) and a spacing structure (265-1 or 265-2). The transistor has an emitter (241), a base (243), and a collector (245). The base is formed with an intrinsic base portion (243I), a base link portion (243L), and a base contact portion (245C). The intrinsic base portion is situated below the emitter and above material of the collector. The base link portion extends between the intrinsic base portion and the base contact portions. The spacing structure includes an isolating dielectric layer (267-1 or 267-2) and a spacing component. The dielectric layer extends along the upper semiconductor surface. The spacing component includes a lateral spacing portion (269-1 or 269-2) of largely non-monocrystalline semiconductor material, preferably polycrystalline semiconductor material, situated on the dielectric layer above the base link portion. Opposite first and second upper edges of the lateral spacing portion (275-1 and 277-1) laterally conform to opposite first and second lower edges (297-1 and 299-1) of the base link portion so as to determine, and thereby control, its length.
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 0.1 μm deep into the body material. The source/drain zones (140 and 142 or 160 and 162) of a p-channel IGFET (120 or 122) are provided with graded-junction characteristics to reduce junction capacitance, thereby increasing switching speed.