Abstract: A mask ROM uses a bit line structure having a vertically graded dopant distribution or a distinct two level dopant distribution. A bit line might include a highly doped region buried deeply within the substrate that is connected to a comparatively lightly doped region formed above the more highly doped region. The vertical structure of the bit line allows the bit line to be less resistive than the simpler shallow bit line structure conventionally used. The vertical structure (i.e., the two level or graded structure) of the bit line allows the bit line to have a lower doping immediately adjacent the channel region, which reduces the likelihood of punchthrough. The deeper, highly doped portions of the bit line are narrow and laterally confined so that well defined antipunchthrough implantations can be formed which lie between but separated from the more highly doped portions of the bit lines.

Abstract: A side wall spacer and a spacer layer are concurrently formed from an insulating layer in such a manner that the side wall spacer is on one side surface of a gate electrode and the spacer layer covers a drain forming area and the other side surface of the gate electrode, and n-type dopant impurity is ion implanted into the drain forming area and a source forming area, thereby concurrently forming a shallow drain region and a deep source region on both sides of the gate electrode.

Abstract: The present invention provide a method for forming a triple well. The triple well includes an n-well, a first p-well surrounded with the n-well and a second p-well apart from the first p-well and adjacent to the n-well. According to the present invention, only one conductivity type of impurities are implanted in each well. Therefore, it is possible to prevent the decrease of the carrier mobility and increase of the leakage current.

Abstract: A method is described for forming trench isolation for integrated circuits on silicon wafers by selectively doping the trench regions by ion implantation and then etching these areas with a wet chemical etch. A dopant such as boron, is implanted in a sequence of energies and doses to provide a desired trench profile of heavily doped silicon. The implanted silicon etches far more rapidly than the surrounding silicon and is readily etched out forming a trench. The concentration of dopant diminishes rapidly in the periphery of the implanted region. As the etch front approaches the periphery, the silicon etch rate, likewise diminishes and the etch can be quenched to leave a uniform surface layer of enhanced boron concentration which lines the resultant trench to form an effective channel stop. Wet etched trenches provide advantages over trenches formed by RIE including smooth rounded trench profiles which reduce stress. In addition, trenches having widths below 0.

Abstract: A flash memory formed by a process wherein at least two parallel stacked gate strips are formed on a silicon substrate such that the stacked gate strips are separated by field oxide islands. Asymmetrical first and second junctions are formed in each of a set of source/drain regions and a chemical etch is applied to form the field oxide islands into oxide spacers that align a dual-function control line to the first and second junctions. The resulting flash memory includes a plurality of stacked gate islands, one or more source/drain regions between at least a subset of the plurality of stacked gate islands, first junctions in each of the source/drain regions, second junctions in each of the source/drain regions and dual function control lines in the source/drain regions.

Abstract: A method of forming high voltage device. A first type semiconductor having at least a gate formed thereon is provided. A first ion implantation with a second type dopant is performed to form a first diffusion region in the semiconductor substrate. An oxide layer is formed on the semiconductor substrate. A second ion implantation with the second type dopant is performed to form a second diffusion region within the first diffusion region. A silicon nitride layer is formed on the oxide layer, through which an opening penetrates to exposed the oxide layer. A third ion implantation with the second type dopant is performed using the silicon nitride layer as a mask to form a third diffusion region within the second diffusion region. Drive-in is performed to deepen the third diffusion region. The silicon nitride layer is removed. The exposed oxide layer is transformed into a field oxide layer.

Abstract: A method for fabricating a CMOS device having BILLI (buried implanted layers for lateral isolation) structure capable of effectively preventing latch-up is disclosed, having the following steps. A mask pattern is formed on the semiconductor substrate of a predetermined conductivity type to expose a region where the MOS transistor, having a same conductivity type as that of the substrate, is to be formed wherein the mask pattern has a vertical boundary face having a gradual slope. A buried layer is then formed in the form of island by ion-implanting the impurity ions into the substrate to pass through the mask pattern, the buried layer having a same conductivity type as that of the substrate, and being formed to be continuous under the vertical boundary face of the mask pattern.

Abstract: A method in the manufacture of ultra-large scale integrated circuit semiconductor devices suppresses boron loss due to segregation into the screen oxide during the boron activation rapid thermal anneal. A nitridation of the screen oxide is used to incorporate nitrogen into the screen oxide layer prior to boron implantation for ultra-shallow, source and drain extension junctions. A second nitridation of a second screen oxide is used prior to boron implantation for deeper, source and drain junctions. This method significantly suppresses boron diffusion and segregation away from the silicon substrate which reduces series resistance of the complete source and drain junctions.

Abstract: A method of fabricating an MOS device that includes self-aligned suicides, the method including two amorphization implantations, both of which follow formation of the self-aligned source/drain regions of the device but precede formation of the self-aligned suicides. The first consists of implantation of low-energy heavy ions, preferably of energies 15-20 keV, while the second consists of implantation of more energetic heavy ions, preferably of energies at least 40 keV.

Abstract: A method for fabricating a metal oxide semiconductor field effect transistor wherein source/drain junctions are formed by depositing and etching an oxide film having a desired thickness prior to the formation of a pocket region carried out by a pocket ion implantation after forming a gate oxide film and gate electrode on a channel region formed by implanting impurity ions in a silicon substrate. The pocket region is formed by impurity ions in source/drain regions exposed by etching the oxide film. Accordingly, it is possible to reduce the thermal budget applied to the source/drain junctions. As a result, the lateral diffusion of the impurity ions implanted in the source/drain junctions can be suppressed as much as possible. That is, the transistor fabricated in accordance with the present invention has a channel length longer than that obtained in accordance with the prior art. Accordingly, the transistor can have a highly compact or densely integrated size.

Abstract: A system and method for providing a memory in a semiconductor is disclosed. In one aspect, the method and system include providing a source implant in the semiconductor, providing a first anneal of the source implant in an oxidizing agent, and providing a drain implant in the semiconductor after the first anneal. In another aspect, the method and system include providing a source implant and a drain implant in the semiconductor, providing a mask, and providing an anneal of the source implant, the drain implant, and the mask in an oxidizing agent. The mask exposes the source implant while limiting exposure of at least a portion of the drain implant.

Abstract: An IGFET with source and drain contacts in close proximity to a gate with sloped sidewalls is disclosed. A method of making the IGFET includes forming a gate over a semiconductor substrate, wherein the gate includes a top surface, a bottom surface and opposing sidewalls, and the top surface has a substantially greater length than the bottom surface, forming a source and a drain that extend into the substrate, depositing a contact material over the gate, source and drain, and forming a gate contact on the gate, a source contact on the source, and a drain contact on the drain. The gate is separated from the source and drain contacts due to a retrograde slope of the gate sidewalls, and the gate contact is separated from the source and drain contacts due to a lack of step coverage in the contact material. Preferably, the contact material is a refractory metal, and the contacts are formed by converting the refractory metal into a silicide.

Abstract: An improved method for forming a triple well of a semiconductor device which is capable of more simply and easily forming a triple well without removing an anti-oxidation film.

Abstract: The present invention advantageously provides a method for forming a test structure for determining how LDD length of a transistor affects transistor characteristics. In one embodiment, a first polysilicon gate conductor is provided which is laterally spaced from a second polysilicon gate conductor. The gate conductors are each disposed upon a gate oxide lying above a silicon-based substrate. An LDD implant is forwarded into exposed regions of the substrate to form LDD areas within the substrate adjacent to the gate conductors. A first spacer material is then formed upon sidewall surfaces of both gate conductors to a first pre-defined thickness. Source/drain regions are formed exclusively within the substrate a spaced distance from the first gate conductor, the spaced distance being dictated by the first pre-defined thickness. A second spacer material is formed laterally adjacent to the first spacer material to a second pre-defined distance.

Abstract: A process is disclosed for forming one or more doped regions beneath the surface of a single crystal semiconductor substrate, such as retrograde wells or deeper source/drain regions, by implantation at low energy which comprises orienting the crystal lattice of the semiconductor substrate, with respect to the axis of the implantation beam, i.e., the path of the energized atoms in the implantation beam, to maximize the number of implanted atoms which pass between the atoms in the crystal lattice. This results in the peak concentration of implanted atoms in the crystal lattice of the single crystal semiconductor substrate being deeper than the peak concentration of implanted atoms in the substrate would be if the axis of the implantation beam were not so oriented with respect to the crystal lattice of the semiconductor substrate during implantation.

Abstract: A high voltage NMOS device includes an extended drain region formed by implantation of arsenic and phosphorus and a drivein of both the species. The dosage of arsenic is substantially higher than the dosage of phosphorus, so that upon drivein, the slower diffusing arsenic is highly concentrated near the surface of the extended drain region, while the more rapidly diffusing phosphorus provides a gradual gradient of concentration of dopant into the extended drain region.

Abstract: A flash memory cell is fabricated by forming a lightly-doped region with only an implantation procedure to avoid lateral diffusion resulting from an increased overlap between the source region and gate as well as a short channel effect, while surrounding the source region with the lightly-doped region to thereby increase the breakdown voltage between the source region and the substrate.

Abstract: The nonvolatile semiconductor memory of this invention includes: a semiconductor substrate; a plurality of memory cells formed in a matrix on the semiconductor substrate, each of the memory cells including a first insulating film formed on the semiconductor substrate, a floating gate formed on the first insulating film, and a control gate formed on the floating gate via a second insulating film sandwiched therebetween, a source diffusion region, and a drain diffusion region; a diffusion layer formed in a portion of the semiconductor substrate located between two of the memory cells adjacent in a first direction, the diffusion layer including the drain diffusion region for one of the two memory cells and the source diffusion region for the other memory cell; a word line formed by connecting the control gates of the memory cells lined in the first direction; and a bit line formed by connecting the diffusion layers lined in a second direction substantially perpendicular to the first direction, wherein the memory

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: A semiconductor fabrication process is presented which optimizes the position of impurities within a gate conductor a the source/drain straddling the gate conductor. Optimal positioned is achieved by using separate implants of different energies depending upon whether the gate conductor connotes a PMOS or NMOS transistor. A layer of polysilicon used to form the gate conductor is doped before patterning so that the source and drain regions are protected. A low energy implant is performed when implanting a fast diffuser such as boron, and a high energy implant is performed when implanting a slow diffuser like arsenic. This enables optimum positioning of the impurities throughout the gate conductor cross-section after heat cycles are applied. Fast diffusers are initially placed far from the bottom surface of the polysilicon, and diffuse near the bottom surface of the polysilicon when heat is applied.

Abstract: A structure for improving latch-up immunity and interwell isolation in a semiconductor device is provided. In one embodiment, a substrate has an upper surface and a first dopant region formed therein. The first dopant region has a lower boundary located below an upper surface of the substrate and a side boundary extending from the upper surface of the substrate to the lower boundary of the first dopant region. A heavily doped region having a first portion and a second portion located along the lower boundary and the side boundary of the first dopant region, respectively, has a substantially uniform dopant concentration greater than a dopant concentration of the first dopant region. The heavily doped region improves latch-up immunity and interwell isolation without degrading threshold voltage tolerance.

Abstract: CMOS vertically modulated wells are constructed by using a blanket implant to form a blanket buried layer and then using clustered MeV ion implantation to form a structure having a buried implanted layer for lateral isolation in addition to said blanket buried layer.

Abstract: The double lightly diffused transistor has drain regions with a lightly doped arsenic region 42 entirely contained within a lightly doped phosphorus region 40. The arsenic region is implanted with a dose less than 1.times.10.sup.15 ions/cm.sup.2 and is preferably implanted with a dose of about 3.times.10.sup.3 to 2.times.10.sup.14 ions/cm.sup.2. The drains are silicided for ohmic contact.

Abstract: A method for fabricating an MOS transistor of an LDD structure having reduced short channel effects and GIDL (Gate Induced Drain Leakage) including the steps of providing a semiconductor substrate, forming a field oxide film in a field region of the semiconductor substrate, forming a gate electrode having a gate insulating film and a cap gate insulating film in an active region on the semiconductor substrate, forming L-shaped insulating sidewalls at sides of the gate electrode, forming high density source/drain regions in the semiconductor substrate in the active region using the gate electrode and the L-shaped insulating sidewalls as masks,etching the L-shaped insulating sidewalls into I-shaped insulating sidewalls, and forming lightly doped source/drain regions in the semiconductor substrate active region using the I-shaped insulating sidewalls and the gate electrode as masks.

Abstract: CMOS vertically modulated wells have a structure with a buried implanted layer for lateral isolation (BILLI). This structure includes a field oxide area, a first retrograde well of a first conductivity type, a second retrograde well of a second conductivity type adjacent the first well, and a BILLI layer below the first well and connected to the second well by a vertical portion. This structure has a distribution in depth underneath the field oxide which kills lateral beta while preventing damage near the surface under the field oxide.

Abstract: A thin film transistor for an antistatic circuit includes: wells formed on a silicon substrate; insulating layers for electrical isolation between electrodes formed within the wells; low density impurity diffused regions respectively interposed between the insulating layers; a first high-density impurity diffused region formed within one low-density impurity diffused region; a second high-density impurity diffused region formed within the other low-density impurity diffused region; interlevel insulating layers formed on the insulating layers and the low-density impurity diffused layers; and metal gate electrodes formed on the low-density impurity diffused layers and the interlevel insulating layers; at least one of the first high-density impurity diffused region and the second high-density impurity diffused region being arranged to overlap an active region, inward from outside edges of the active region.

Abstract: A selectively doped MOS transistor channel includes a deep impurity distribution and shallow impurity distribution. The deep impurity distribution is formed within high energy implant with an impurity of conductivity type opposite to the conductivity type of the source/drain regions of the transistor. In the n-channel regions, the deep impurity distribution preferably includes boron ions. The deep impurity distribution acts as a channel stop such that adjacent source/drain regions of the like type transistors are not inadvertently coupled during circuit operation. The shallow impurity distribution acts as a threshold implant by precisely controlling the doping of the transistor channel in the vicinity of the silicon oxide interface. The peak concentration of the shallow impurity distribution is located at a depth below the silicon surface which is greater than a depth typically associated with a threshold adjust implant.

Abstract: A method of manufacturing a semiconductor device comprises; forming a device isolation region in a semiconductor substrate; forming at least a first conductivity type impurity region in the semiconductor substrate; and forming on the semiconductor substrate a transistor including a gate insulating film, a gate electrode, source/drain regions and a channel located directly under the gate electrode, wherein the first conductivity type impurity region is formed by the steps of: an ion implantation 1 having a concentration peak at a location deeper than the bottom of the device isolation region; an ion implantation 2 having a concentration peak at a location around the bottom of the device isolation region; an ion implantation 3 having a concentration peak around the junction regions where the source/drain regions are to be formed; and an ion implantation 4 having a concentration peak on the surface or directly under the surface of the region where the channel is to be formed.

Abstract: A simplified fabrication procedure for making flash EEPROM memory cells is disclosed. The method comprises performing a double-diffuse (deep) junction implant after the shallow source/drain of the memory cell have been implanted and formed. A high energy double-diffuse implant is used to replace separate, individual implant and diffusion steps which results in a memory cell having, less damage to its substrate.

Abstract: The present invention is a method of manufacturing a high/low resistance on a mix-mode product. The method includes forming a polysilicon layer over a wafer. A blanket ion implantation is performed to implant ions into the entire polysilicon layer. The polysilicon layer is then separated into a high resistance area and a low resistance area. The low resistance area top surface is raised higher than the high resistance area. A photoresist is then formed on the polysilicon areas. The photoresist is subsequently etched back to the top surface of the low resistance areas. A second implant is done on the low resistance area.

Abstract: A semiconductor fabrication method is provided for forming transistors upon a semiconductor substrate wherein the semiconductor substrate has first, second and third substrate regions. A single mask layer is formed over the semiconductor substrate. The single mask layer has a first mask portion covering the first substrate region, a second mask portion exposing the second substrate region, and a third mask portion partially covering the third substrate region. A first type impurity dopant is differentially introduced into the first, second and third substrate regions according to the single mask layer. First, second and third transistors are formed in the first, second and third substrate regions, respectively. The first and second transistors have differing conductivity types and the first and third transistors have the same conductivity type. The first and third transistors also have differing threshold voltages according to the differential introducing of the dopant.