Abstract:
An asymmetric insulated-gate field-effect transistor (100 or 102) has a source (240 or 280) and a drain (242 or 282) laterally separated by a channel zone (244 or 284) of body material (180 or 182) of a semiconductor body. A gate electrode (262 or 302) overlies a gate dielectric layer (260 or 300) above the channel zone. A more heavily doped pocket portion (250 or 290) of the body material extends largely along only the source. The source has a main source portion (240M or 280M) and a more lightly doped lateral source extension (240E or 280E). The drain has a main portion (242M or 282M) and a more lightly doped lateral drain extension (242E or 282E). The drain extension is more lightly doped than the source extension. The maximum concentration of the semiconductor dopant defining the two extensions occurs deeper in the drain extension than in the source extension. Additionally or alternatively, the drain extension extends further laterally below the gate electrode than the source extension. These features enable the threshold voltage to be highly stable with operational time.
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 (100 or 102) has a source (240 or 280) and a drain (242 or 282) laterally separated by a channel zone (244 or 284) of body material (180 or 182) of a semiconductor body. A gate electrode (262 or 302) overlies a gate dielectric layer (260 or 300) above the channel zone. A more heavily doped pocket portion (250 or 290) of the body material extends largely along only the source. The source has a main source portion (240M or 280M) and a more lightly doped lateral source extension (240E or 280E). The drain has a main portion (242M or 282M) and a more lightly doped lateral drain extension (242E or 282E). The drain extension is more lightly doped than the source extension. The maximum concentration of the semiconductor dopant defining the two extensions occurs deeper in the drain extension than in the source extension. Additionally or alternatively, the drain extension extends further laterally below the gate electrode than the source extension. These features enable the threshold voltage to be highly stable with operational time.
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:
Insulated-gate field-effect transistors (“IGFETs”), both symmetric and asymmetric, suitable for a semiconductor fabrication platform that provides IGFETs for analog and digital applications, including mixed-signal applications, utilize empty-well regions in achieving high performance. A relatively small amount of semiconductor well dopant is near the top of each empty well. Each IGFET (100, 102, 112, 114, 124, or 126) has a pair of source/drain zones laterally separated by a channel zone of body material of the empty well (180, 182, 192, 194, 204, or 206). A gate electrode overlies a gate dielectric layer above the channel zone. Each source/drain zone (240, 242, 280, 282, 520, 522, 550, 552, 720, 722, 752, or 752) has a main portion (240M, 242M, 280M, 282M, 520M, 522M, 550M, 552M, 720M, 722M, 752M, or 752M) and a more lightly doped lateral extension (240E, 242E, 280E, 282E, 520E, 522E, 550E, 552E, 720E, 722E, 752E, or 752E). Alternatively or additionally, a more heavily doped pocket portion (250 or 290) of the body material extends along one of the source/drain zones. When present, the pocket portion typically causes the IGFET to be an asymmetric device.
Abstract:
An insulated-gate field-effect transistor (100) provided along an upper surface of a semiconductor body contains a pair of source/drain zones (240 and 242) laterally separated by a channel zone (244). A gate electrode (262) overlies a gate dielectric layer (260) above the channel zone. Each source/drain zone includes a main portion (240M or 242M) and a more lightly doped lateral extension (240E or 242E) laterally continuous with the main portion and extending laterally under the gate electrode. The lateral extensions, which terminate the channel zone along the upper semiconductor surface, are respectively largely defined by a pair of semiconductor dopants of different atomic weights. With the transistor being an asymmetric device, the source/drain zones constitute a source and a drain. The lateral extension of the source is then more lightly doped than, and defined with dopant of higher atomic weight, than the lateral extension of the drain.
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.