Abstract: A method for isolating semiconductor devices comprising providing a semiconductor substrate. The semiconductor substrate includes a first pair of source/drain regions on either side of a first channel region and a second pair of source/drain regions on either side of a second channel region. One of the first pair of source/drain regions is proximal to one of the second pair of source/drain regions. First and second laterally displaced MOS transistors are formed partially within the semiconductor substrate. An isolation trench is formed through the proximal source/drain regions and the trench is filled with a trench dielectric material such that the proximal source/drain regions are electrically isolated whereby the first transistor is electrically isolated from the second transistor.

Abstract: Methods are described to prevent the inherent latchup problem of CMOS transistors in the sub-quarter micron range. Latchup is avoided by eliminating the low resistance between the V.sub.dd and V.sub.ss power rails caused by the latchup of parasitic and complementary bipolar transistor structures that are present in CMOS devices. These goals have been achieved without the use of guard rings by using p-region implants in the n-well to disconnect the pnp collector to npn base connection of two parasitic bipolar transistors. Further, the p-region implants are shorted to a reference voltage V.sub.ss via a p.sup.+ ground tab thus backbiasing the diode-like p-region implants. The proposed methods are compatible with CMOS processes.

Abstract: An IC comprises a tub of a first conductivity type, at least one transistor embedded in the tub, and a first pair of isolating regions defining therebetween a tub-tie region coupled to the tub. The tub-tie region comprises a cap portion of the first conductivity type and an underlying buried pedestal portion of a second conductivity type. At least a top section of the pedestal portion is surrounded by the cap portion so that a conducting path is formed between the cap portion and the tub. In a CMOS IC tub-ties of this design are provided for both NMOS and PMOS transistors. In a preferred embodiment, the cap portion of each tub-tie comprises a relatively heavily doped central section and more lightly doped peripheral sections, both of the same conductivity type.

Abstract: A MOSFET integrated circuit device comprises a lightly doping a semiconductor substrate, with wells formed within the substrate doped with an opposite value dopant, forming a plurality of doped regions within the surface of the substrate and within the surface of the wells, the improvement comprising opening a trench about the periphery of the wells, and filling the trench with a relatively highly conductive material as a guard structure.

Abstract: Over the principal surface of a semiconductor substrate body containing an impurity of a predetermined conduction type, there is formed an epitaxial layer which contains an impurity of the same conduction type as that of the former impurity and the same concentration as the designed one of the former impurity. After this, there are formed a well region which has the same conduction type as that of said impurity and its impurity concentration gradually lowered depthwise of said epitaxial layer. The well region is formed with the gate insulating films of MIS.FETs.

Abstract: The preferred embodiment of the present invention overcomes the limitations of the prior art and provides a device and method to increase the latch-up immunity of CMOS devices by forming implants at the well edges. The preferred method uses hybrid resist to form these implants at the edges of the N-wells and/or P-wells. The implants reduce the lifetime of minority carriers in the parasitic transistor, and hence reduce the gain of the parasitic transistor. This reduces the propensity of the CMOS device to latch-up. The preferred embodiment method allows these implants to be formed without requiring additional masking steps over prior art methods. Furthermore, the preferred method for forming the implants results in implants that are self aligned to the edges of the wells.

Abstract: An improved processing technique results in a structure which maximizes contact area by eliminating a sidewall spacer used to form LDD regions. A sacrificial spacer is provided during processing to form the LDD regions, and is then removed prior to further processing of the device. A sidewall spacer is then formed in a self-aligned contact from a later deposited oxide layer used as an interlevel dielectric. This leaves only a single oxide sidewall spacer alongside the gate electrode, maximizing the surface area available for the self-aligned contact itself.

Abstract: A method of improving latch-up immunity and interwell isolation in a semiconductor device is provided. In one embodiment, an implant mask which has a variable permeability to implanted impurities is formed on the surface of a substrate having a first dopant region. A first portion of the implant mask overlies a first portion of the first dopant region. The structure is subjected to high energy implantation which forms a heavily doped region. A first portion of the heavily doped region is located along the lower boundary of the first dopant region. A second portion of the heavily doped region which extends along a side boundary of the first dopant region is formed by impurity ions which pass through the first portion of the implant mask. The heavily doped region improves latch-up immunity and interwell isolation without degrading threshold voltage tolerance.

Abstract: The present invention discloses a method of forming CMOS transistors with planar shallow trench isolations. Before a twin well being formed, a pad oxide film and a nitride film are sequentially deposited on a silicon substrate. When a photoresist film is patterned to define active regions, the silicon substrate is recessed by using the patterned photoresist film as a mask. A liquid-phase-deposition oxide (LPD) film is then grown on the recess structure for shallow trench isolations. Next, a high temperature annealing procedure is performed to densify the LPD oxide film. Finally, when the pad oxide and the nitride films are removed, processes for fabricating CMOS transistors can be continued on the silicon substrate.

Abstract: The invention provides an isolation technique using fewer process steps and a double charged implantation step (141) for defining a well region (139) of a CMOS integrated circuit device. The invention provides steps of providing a semiconductor substrate comprising an multiple layer of films (105, 107, 109). These films include an oxide layer (105) overlying the substrate, a polysilicon layer (107) overlying the oxide layer, and a nitride layer (109) overlying the polysilicon layer. The invention also uses a step of removing a first portion of the nitride layer and a first portion of the polysilicon layer defined underlying the first portion of the nitride layer and removing a second portion of the nitride layer and a second portion of the polysilicon layer defined underlying the second portion of the nitride layer. This sequence of steps provides a partially completed semiconductor structure that defines isolation regions before forming well regions for active devices.

Abstract: A method to form, in a NMOS area, a shallow trench isolation (STI) having B doped sidewalls regions 44 to reduce the NMOS reverse narrow width effect in narrow active areas 12N (e.g., narrow channel regions <0.1 .mu.m wide). A substrate is provided having a NMOS area 13 and a PMOS area 15. A pad oxide layer 20 and a barrier layer 22 are formed on the substrate. Trenches 24 are etched in the substrate 10 in the NMOS and PMOS areas. The etching forms narrow active areas 12N and wide active areas 12W. The narrow active areas 12N have a width between 0.4 and 1.0 .mu.m. A liner layer 30 is grown on the sidewalls and bottom of the trench on the substrate. A first photoresist layer is formed covering the PMOS areas and having first opening over the NMOS areas. In a critical step, a large angle Boron implantation is performed into the sidewalls and the bottom of the trenches forming Boron doped regions 44 in the substrate. The first photoresist layer is removed.

Abstract: An integrated circuit includes a plurality of CMOS transistors formed in a monocrystalline substrate. Within the substrate is a plurality of complementary spaced pairs of a p-well region and a n-well region. Between each well region, each of which has a source, gate, and drain, is a self-aligned trench filled with semiconductor material. A method of fabricating a field effect transistor entails a first step of forming a layer of first insulative material over a monocrystalline substrate. Next, a layer of semiconductor material is formed over the first insulative material. A p- or n-well masking layer is formed over the semiconductor layer and patterned to expose a first portion of the underlying semiconductor layer. A first dopant of one polarity is implanted in the region of the substrate aligned with the semiconductor layer first portion, which is then converted into a second insulative material. The masking layer is removed, thereby exposing the remaining portion of the semiconductor layer.

Abstract: A method of manufacturing a semiconductor device having a triple-well structure, includes the steps of: forming a first well layer of a second conductivity type by implanting, as a first ion implantation, impurity ions of the second conductivity type to a specific depth from the surface of a semiconductor substrate of a first conductivity type and then subjecting the semiconductor substrate to an annealing treatment; forming a second ion-implanted region by implanting, as a second ion implantation, impurity ions of the second conductivity type into an end portion of first well layer with a specific width and at a depth from the surface of the semiconductor substrate to the surface of the first well layer to surround the first well layer; forming a third ion-implanted region by implanting, as a third ion implantation, impurity ions of the first conductivity type into a portion of the semiconductor substrate surrounded by the first well layer and the second ion-implanted region and at depth from the surface of

Abstract: A method of establishing a differential threshold voltage during the fabrication of first and second IGFETs having like conductivity type is disclosed. A dopant is introduced into the gate electrode of each transistor of the pair. The dopant is differentially diffused into respective channel regions to provide a differential dopant concentration therebetween, which results in a differential threshold voltage between the two transistors. One embodiment includes introducing a diffusion-retarding material, such as nitrogen, into the first gate electrode before the dopant is diffused into the respective channel regions, and without introducing a significant amount of the diffusion-retarding material into the second gate electrode. Advantageously, a single dopant implant can provide both threshold voltage values. The two threshold voltages may be chosen to provide various combinations of enhancement mode and depletion mode IGFETs.

Abstract: A method for forming a well structure in an integrated circuit such that, without any additional masking steps, the well implantation can be performed before the definition of the active device area. Hence, besides being able to avoid problems caused by a low breakdown voltage, also can provide a self-alignment mark for subsequent mask alignment, thereby reducing misalignment errors.

Abstract: A new method of forming a butted contact in combination with a shallow trench isolation process is described. Shallow trench isolation areas are formed within the semiconductor substrate and filled with an oxide. A first photomask is formed having an opening larger than the butted contact to be formed and exposing a portion of at least one of the shallow trench isolation areas. The oxide is etched away within the shallow trench isolation area where it is exposed forming a misalignment trench wherein the exposed sidewall is adjacent to a P-well. A gate oxide layer is grown on the surface of the substrate and on the exposed sidewall of the misalignment trench. A first polysilicon layer is deposited overlying the gate oxide layer and filling the misalignment trench. The polysilicon and oxide layers are etched away to form gate electrodes and interconnection lines where a portion of the first polysilicon layer remains within the misalignment trench.

Abstract: A method of making an IGFET with a selectively doped multilevel polysilicon gate that includes upper and lower polysilicon gate levels is disclosed.

Abstract: The preferred embodiment of the present invention overcomes the limitations of the prior art and provides a device and method to increase the latch-up immunity of CMOS devices by forming implants at the well edges. The preferred method uses hybrid resist to form these implants at the edges of the N-wells and/or P-wells. The implants reduce the lifetime of minority carriers in the parasitic transistor, and hence reduce the gain of the parasitic transistor. This reduces the propensity of the CMOS device to latch-up. The preferred embodiment method allows these implants to be formed without requiring additional masking steps over prior art methods. Furthermore, the preferred method for forming the implants results in implants that are self aligned to the edges of the wells.

Abstract: The preferred embodiment of the present invention overcomes the limitations of the prior art and provides a device and method to increase the latch-up immunity of CMOS devices by reducing the mobility of carriers between the devices. The preferred embodiment uses an implant formed beneath trench isolation between n-channel and p-channel devices. This implant preferably comprises relatively large/heavy elements implanted into the wafer beneath the trench isolation. The implant elements reduce the mobility of the charge carriers. This increases the latch-up holding voltage and thus reduces the likelihood of latch-up. The implants can be formed without the need for additional photolithography masks.

Abstract: CMOS power device (10) is provided. A tank region (62) is formed in a semiconductor substrate (60). A polysilicon gate layer (34) is disposed above the tank region (62) and defines a plurality of source and drain diffusion openings (38 and 36) having rounded inner corners (40). A plurality of backgate contact regions (42) are segmented and are formed in vacancies in a plurality of source regions (30).