Abstract: The present invention provides methods of forming an out-diffused bitline in a semiconductor substrate by utilizing a laser annealing step wherein the dopant material in the trench region is out-diffused into the semiconductor substrate. The out-diffused bitline can also be formed utilizing an ion implantation step.

Abstract: A method is disclosed for forming a split-gate flash memory cell where the floating gate of the cell is self-aligned to isolation, to source and to word line. This multi-self-aligned structure, which provides the maximum shrinkage of the cell that is possible, is also disclosed. The multi-self-alignment is accomplished by first defining the floating gate at the same time the trench isolation is formed, and then self-aligning the source to the floating gate by using a nitride layer as a hard mask in place of the traditional polyoxide, and finally forming a polysilicon spacer to align the word line to the floating gate. Furthermore, a thin floating gate is used to form a thin and sharp poly tip through the use of a “smiling effect” to advantage.

Abstract: A semiconductor process, which creates a semiconductor devices that includes logic transistors fabricated in a first region and a fieldless array fabricated in a second region, is provided. Both the logic transistors and the fieldless array transistors have gates comprising a polysilicon layer with a silicide layer. The logic transistors have self-aligned silicide regions formed on their source and drain regions. Self-aligned silicide regions are not formed on the source and drain regions of the fieldless array transistors, thereby preventing undesirable electrical shorts which could otherwise occur within the fieldless array.

Abstract: The invention relates to a method of manufacturing a field effect transistor, in particular a discrete field effect transistor, comprising a source region (1) and a drain region (2) and, between said regions, a channel region (4) above which a gate region (3) is located. The gate region (3) is formed by applying an insulating layer (5) to the semiconductor body and providing this insulating layer with a stepped portion (6) in the thickness direction, whereafter a conductive layer (30) is applied to the surface of the semiconductor body (10), which layer is substantially removed again by etching, so that a part (3A) of the conductive layer (30), which part forms part of the gate region (3) and which lies against the stepped portion (6), remains intact.

Abstract: A process for fabricating a semiconductor device includes the step of processing a patterned resist layer to vary the lateral dimensions of the patterned resist layer while forming doped regions in a semiconductor substrate. A graded junction profile is formed by creating a patterned resist layer having a first substantially vertical edge surface. A doping process is carried out to form a first doped region in the semiconductor substrate having a junction profile substantially continuous with the first substantially vertical edge surface. The patterned resist layer is processed to form a second substantially vertical edge surface, which is laterally displaced from the first substantially vertical edge surface. A doping process is carried out to form a second doped region having a junction profile that is substantially continuous with the second substantially vertical edge surface. The junction profiles of the first and second doped regions form a graded junction within the semiconductor substrate.

Abstract: A new FET device configuration for electrically programmable memories (EPROM), flash/electrically erasable and programmable read-only memories (EEPROM), and non-volatile Random Access Memory (NVRAM) which adds vertical components to a previously planar floating gate cell structure; efficiency of electron injection from the channel to floating gate is enhanced by many orders of magnitude because electrons accelerated in the channel penetraite in the direction of movement, straight into the floating gate. The floating gate resides over a series of arbitrary horizontal and vertical channel region components, the key topological feature being that the vertical channel resides near the drain, allowing electrons to penetrate straight into the floating gate. In contrast, the prior art relies on the indirect process of electron scattering by phonon and the 90 degree upward redirection of motion to the floating gate used by conventional Channel Hot Electron EPROM and EEPROM cells.

Abstract: A method of fabricating buried bit line flash EEROM with shallow trench floating gate for suppressing the short channel effect is disclosed. The method comprises following steps. Firstly, a pad oxide layer and a conductive impurity (such as phosphorus) doped polysilicon layer is successively formed on the silicon substrate. Then, an oxidation process is performed to oxidize the polysilicon layer and to drive in the conductive impurities. After coating a patterned mask on the resultant surface to define a plurality of buried bit line regions, a dry etch is used to etch away the unmask regions till the silicon substrate is slightly recessed to form shallow trenches. Subsequently, the photoresist is stripped, and a gate dielectric layer, such as gate nitride or oxynitride layer is formed on the resultant surface.

Abstract: A method for simultaneously forming a bit-line contact and a node contact first forms a polysilicon layer and a first insulator on a substrate, and then patterns patterning the polysilicon layer and the first insulator, wherein the substrate consists of an active area and an isolation area. Next, a second insulator is formed on the exposed substrate and the first insulator. Then, by forming a photoresist layer on the second insulator and patterning the photoresist layer, a pattern containing a bit-line contact pattern and a node contact pattern is transferred onto the second insulator. By performing an etching back process on the second insulator, the bit-line contact and the node contact are formed simultaneously in a self-aligned way.

Abstract: A method is provided for fabricating a nonvolatile memory device having a simple stacked stricture with program gates. The method includes forming bitlines of second conductivity type along a first direction separated by a first prescribed distance in a substrate of a first conductivity type and forming first lines on the substrate along a second direction separated from one another by a second prescribed distance. The second direction is substantially perpendicular to the first direction, and the first lines include a first conductive layer on an isolating layer. A gate insulating layer is formed on the substrate and a tunneling insulating layer on the first conductive lines and a second conductive layer is formed on the entire surface. The second conductive layer, the tunneling insulating layer, and the first conductive lines are selectively removed to form second conductive lines along the first direction and program gates.

Abstract: Methods of forming EEPROM memory cells having uniformly thick tunneling oxide layers include the steps of forming a preliminary field oxide isolation region of first thickness at a face of a semiconductor substrate of first conductivity type (e.g., P-type) and then forming a tunneling oxide layer on the face, adjacent the preliminary field oxide isolation region. The memory cell's drain region dopants are then implanted through the preliminary field oxide isolation region and into the substrate to form a preliminary drain region of second conductivity type. The preliminary field oxide isolation region is then grown to a second thickness greater than the first thickness by oxidizing the portion of the substrate containing the implanted dopants, to form a final field oxide isolation region which may have a thickness of about 2000 .ANG..

Abstract: A method for making capacitor-over-bit line (COB) DRAM using a self-aligned contact etching technology is achieved. After forming FET gate electrodes, sidewall spacers are formed from a first Si.sub.3 N.sub.4 etch-stop layer, while a portion of the Si.sub.3 N.sub.4 is retained as an etch-stop layer on the source/drain areas. Self-aligned contact openings are etched in a first oxide layer to the source/drain areas, and polysilicon landing plugs are formed in all the self-aligned openings. A second oxide layer is deposited and contact holes are etched to the landing plugs for bit lines. A polycide layer having a cap layer is deposited and patterned to form bit lines. A third Si.sub.3 N.sub.4 etch-stop layer is conformally deposited over the bit lines and patterned to form openings over the landing plugs for the capacitor node contacts while forming Si.sub.3 N.sub.4 sidewall spacers on the bit lines exposed in the openings.

Abstract: A method for forming CMOS DRAM circuitry is disclosed and which includes forming a substrate comprising an array NMOS region, a peripheral NMOS region, and a peripheral PMOS region; forming a pair of insulated and spaced gate lines in the array NMOS region; forming at least one electrically conductive plug in the array NMOS region and which spans between the pair of gate lines; forming a barrier layer over the pair of gate lines in the array NMOS region, the peripheral NMOS and the peripheral PMOS region; and patterning and etching in the peripheral PMOS region to form peripheral PMOS region gate lines including removing a portion of the barrier layer in the PMOS peripheral region and leaving barrier layer material in the NMOS region masking over the electrically conductive plug

Abstract: The present invention provides a polycrystalline silicon conducting structure (e.g., a resistor) whose resistance value is controlled, and can be less variable and less dependent on temperature with respect to any resistant value, and a process of producing the same. Use is made of at least a two-layer structure including a first polycrystalline silicon layer of large crystal grain size and a second polycrystalline silicon layer of small crystal grain size, and the first polycrystalline silicon layer has a positive temperature dependence of resistance while the second polycrystalline layer has a negative temperature dependence of resistance, or vice versa. Moreover, the polycrystalline silicon layer of large grain size can be formed by high dose ion implantation and annealing, or by depositing the layers by chemical vapor deposition at different temperatures so as to form large-grain and small-grain layers.

Abstract: A method for manufacturing a memory array having a plurality of memory cells thereon and diffusion areas therebetween includes the steps of laying down a layer of silicon nitride, defining the diffusion areas and creating diffusion oxides over the diffusion areas. Both steps of laying down and defining occur without etching any part of the layer of silicon nitride. The step of creating diffusion oxides includes the steps of creating porous silicon nitride from portions of the silicon nitride layer wherever diffusion oxides are desired (typically by laying down photoresist in a desired pattern and bombarding the silicon nitride layer with ions) and oxidizing both the porous silicon nitride and the silicon substrate through the porous silicon nitride thereby to create silicon oxy-nitride and silicon dioxide, respectively. The present invention also includes a semiconductor chip having diffusion or bit line oxides formed of at least silicon oxy-nitride.

Abstract: A method of forming buried bit lines. A silicon-on-insulator (SOI) substrate includes a silicon base layer, a first insulation layer and an epitaxial silicon layer. A shallow trench isolation (STI) layer that contacts the first insulation layer is formed in the epitaxial silicon layer. A trench that penetrates the STI layer and runs deep into the first insulation layer is formed. A buried bit line is formed inside the trench such that the top surface of the buried bit line is located between the upper and the lower surface of the STI layer. A second insulation layer is next formed over the buried bit line such that the top surface of the second insulation layer is at the same level as the top surface of the epitaxial silicon layer. A plurality of word lines and a plurality of source/drain regions are formed over the substrate and in the epitaxial silicon layer.

Abstract: A non-volatile memory cell and a manufacturing process therefor are discussed. The cell is integrated in a semiconductor substrate and includes a floating gate transistor having a first source region, first drain region, and gate region projecting over the substrate between the first source and drain regions. The cell also includes a selection transistor having a second source region, second drain region, and respective gate region, projecting over the substrate between the second source and drain regions. The first and second regions are lightly doped and the cell comprises mask elements.

Abstract: A system and method for providing a memory cell on a semiconductor is disclosed. The memory cell has a source and a drain. The method and system include providing a source implant in the semiconductor, providing a pocket implant in the semiconductor, and providing a drain implant in the semiconductor after the pocket implant is provided. Thus, short channel effects are reduced.

Abstract: An EEPROM system having an array of memory cells that individually include two floating gates, bit line source and drain diffusions extending along columns, steering gates also extending along columns and select gates forming word lines along rows of floating gates. The dual gate cell increases the density of data that can be stored. Rather than providing a separate steering gate for each column of floating gates, an individual steering gate is shared by two adjacent columns of floating gates that have a diffusion between them. Processing methods of forming such a cell array include two etching steps to separate strips of conductive material into individual floating gates that are self-aligned with source/drain diffusions and other gate elements. In one embodiment, this is accomplished by two etching steps with separate masks.

Abstract: In a non-volatile semiconductor memory device making electrical writing and erasing possible, source diffusion layers arranged on a substrate and along at least control gate electrodes have, in one part thereof, inclined portions having an angle larger than an ion implantation angle. According to this, device isolation technique is used to lower the resistance of the source diffusion layer.

Abstract: A flash memory structure is formed by a method comprising the steps of providing a semiconductor substrate, and then forming a shallow first trench within the substrate. Thereafter, a buried doped region is formed underneath the first trench so that the buried doped region is at a distance from the substrate surface. The buried doped region is one major aspect in this invention that can be applied to the processing of shallow trench isolation and is capable of reducing device area. Next, a deeper second trench is etched in the substrate. The second trench has a greater depth than the depth of the first trench. Subsequently, insulating material is deposited into the first and the second trench, and then a stacked gate structure is formed above the substrate. Later, the surface source region and drain region are formed on two sides of the stacked gate structure. Through thermal operation, the surface source region alternately connects with the buried doped region to form a buried common source region.

Abstract: A method of fabricating a semiconductor device having a memory array (9) that includes a source line (24) is provided. The method of forming the source line (24) may include providing a semiconductor substrate (52) having a source region (60) separated from a drain region (62) by a channel region (64). An isolation structure (70) may be formed in the semiconductor substrate (52). The isolation structure (70) may cross the source region (60), the drain region (62), and the channel region (64) of the semiconductor substrate (52). An isolation dielectric material (78) may be formed within the isolation structure (70). A continuous stack structure (50) may be formed outwardly from the channel region (64) of the semiconductor substrate (52) and the isolation structure (70). A first photomask (100) may be formed outwardly from the continuous stack structure (50) and the semiconductor substrate (52).

Abstract: A memory device comprising a semiconductor material substrate with a dopant of a first type; a first semiconductor material well with a dopant of a second type formed in the substrate; a second semiconductor material well with a dopant of the first type formed in said first well; an array of memory cells formed within said second well. Each memory cell comprises a first electrode and a second electrode respectively formed by a first and a second doped regions with dopant of the second type formed in said second well, and a control gate electrode.

Abstract: A DMOS structure is formed with P-body and N-source implantations are self-aligned using the same photoresist mask. Following formation of field isolation structures and removal of the composite nitride, a `double-implantation` of P body and N source is made using a single resist masking stage. This process flow utilizes a relatively low N-source implantation dose, as N-source and P-body implantations are subsequently thermally diffused together (co-driven) using the original thermal budget of the P-body drive-in. The N-source implant thus now sees the same thermal budget as does the P-body implant. As a result in this process scheme, overetching of P-body and N-source during composite nitride removal is eliminated, while process simplicity is conserved. Moreover, channel overlap remains self-aligned by implanting N-source and P-body through the same mask. Differing rates of thermal diffusion of the P and N type dopant determine the extent of channel overlap.

Abstract: A method for manufacturing a semiconductor memory device, including the steps of: forming a plurality of stripes comprising a first floating gate material film and a ion implantation protective film, covering one longitudinal side wall of the stripes with a resist pattern; removing a given width of the other side wall of the first floating gate material film by an isotropic etching in use of the resist pattern as a mask; forming an impurity region of low concentration by implanting impurity ions of a second conductivity type into the semiconductor substrate of the first conductivity type in use of the ion implantation protective film as a mask in a tilted direction after removing the resist pattern; and forming asymmetrical impurity regions on both sides of the stripe like first floating gate material film as viewed in the cross section along the direction perpendicular to the longitudinal direction of the stripes.

Abstract: A semiconductor integrated circuit such as a flash memory device with a novel isolation structure. Field isolation (130) is defined on a substrate (10). A spacer (107) is formed at the edges of the field isolation to protect the field isolation from oxide loss during subsequent processing steps, such as HF dips to remove polysilicon or polymer stringers that are often a part of a flash EEPROM process, for example.

Abstract: Disclosed are an improved semiconductor memory cell suitable for high integration and a novel method of fabricating the same. The memory cell has a large capacitance and a small area. The memory cell also has a plurality of bit-lines buried in an isolation region in a semiconductor substrate. The bit-line has a very small width and thickness thereby reducing a parasitic capacity between the bit-line and the semiconductor substrate. The memory cell may further be provided with a noise shielding line. Further, disclosed is a novel memory cell array of a semiconductor memory. The buried bit-line is coupled with a bit-line connecting sub-arrays and both are separated by a insulation film. A plurality of pairs of the bit-lines are arranged in rows. A word-line is coupled with a sub-word line and both are separated by a insulation film. A plurality of pairs of the word-lines are arranged in columns. The memory cells are arranged at the intersections of the buried bit-lines and the word-lines.

Abstract: A method of fabricating buried bit line flash EEROM with shallow trench floating gate for suppressing the short channel effect is disclosed. The method comprises following steps: Firstly, a pad oxide layer and a n+ (such as phosphorus) doped oxide layer is successively formed on the silicon substrate. Then, a nitride layer is deposited on all surfaces as an antireflection coating layer. After coating a patterned mask on the nitride layer to define a plurality of buried bit line regions, a dry etch is used to etch the unmask region till the silicon substrate is slightly recessed to form shallow trenches. Subsequently, the photoresist is stripped, and an oxidation process to grow an oxynitride layer on resultant surface and form buried bit line using dopants in the oxide layer as a diffusion source. After refilling a plurality of trenches with n+ doped silicon layer, a planarization process such as CMP is done to form a plain surface using the nitride layer as an etching stopped layer.

Abstract: A method for fabricating an OTP-ROM includes a first polysilicon layer formed over a semiconductor substrate. An ion implanting process is performed to form a diffusion region inside the substrate on both sides of the first polysilicon layer. This diffusion region acts as a bit line. Then, a second polysilicon layer is formed to cover the first polysilicon layer. The second polysilicon layer is patterned to form a control gate. The patterning process is continued to further pattern the first polysilicon layer to form a floating gate.

Abstract: In a method of manufacturing a semiconductor device, diffusion layers are formed on a semiconductor substrate using a mask. The diffusion layers has a conductive type different from that of the semiconductor substrate. Then, insulating films are formed on the diffusion layers using the mask and the mask is removed. Subsequently, a floating gate is formed between the insulating films on the semiconductor substrate via a first gate insulating film. Next, a second gate insulating film is formed on the floating gate and the insulating films, and a word line is formed to cover the floating gate via the second gate insulating film.

Abstract: The present invention includes forming word lines on a substrate. Next, nitride spacers are formed on the side walls of the word lines. In the cell area, a photoresist is patterned on the substrate to cover a coding region. Then, an ion implantation with n type conductive dopant is carried out to form buried bit lines in the cell area and in the peripheral area adjacent to the word lines. Afterwards, the photoresist is stripped. A high temperature thermal oxidation is then performed to activate the dopant and to form thick oxide structures to isolate the adjacent buried bit lines.

Abstract: Arrangements are provided to increase the process control during the fabrication of the floating/control gate configuration in a non-volatile memory semiconductor device. The arrangements effectively reduce the severity of the topology attributable to the space between adjacent floating gates by advantageously reducing the height of the floating gates in particular locations. The reduced height floating gate's topology allows a subsequently formed control gate to be formed without significant surface depressions. Significant surface depressions in the control gate can lead to cracks in the silicide layer that is formed on the control gate. The cracking usually occurs during subsequent thermal processing of the semiconductor device. Thus the disclosed arrangements prevent cracking of the silicide layer on the control gate, which can affect the performance of the semiconductor device by increasing the resistance of the control gate arrangement.

Abstract: A method is provided for forming a split-gate flash memory cell having reduced size, partially buried source line, increased source coupling ratio, improved programmability, and overall enhanced performance. A split-gate cell is also provided with reduced size and improved performance. The source line is formed in a trench in the substrate over the source region. The trench walls provide increased source coupling and the absence of gate bird's beak with the trench together shrink the cell size. Programmability is also enhanced through more favorable hot electron injection though intergate oxide between the floating gate and the control gate.

Abstract: The present invention proposes a method for fabricating a high-density shallow trench contactless nonvolatile memory. First, a stacked pad oxide/silicon nitride layer is deposited on the substrate and the buried bit line region is defined by a photoresist. An anisotropic etching follows to etch the silicon layer and then the n+ impurity ions are implanted to form the source and drain. After stripping the photoresist, a high temperature steam oxidation process is used to grow a thick field oxide, and the doped ions are active and driven in to form the buried bit lines simultaneously. The silicon nitride layer and the pad oxide layer are then removed, and the silicon substrate is recessed by using the field oxide as an etching mask. After rounding the trench corners by using thermal oxidation and etching back processes, a thin silicon oxy-nitride film is regrown. An in-situ doped polysilicon film is deposited to refill the trench region and then etch back by using a CMP process to form the floating gates.

Abstract: An improved process of fabricating a read only memory device (ROM's) wherein the buried N+ lines have desirable very narrow widths and are closely spaced. The process provides that masking stripes are formed with vertical sidewalls and that spacers are formed on the sidewalls. The areas between the spacers are filled in. The spacers are etched away to form narrow closely spaced openings. Ions are implanted through the openings to form closely spaced buried lines.

Abstract: A semiconductor device and a fabrication method thereof which are capable of achieving a lightly doped drain (LDD) construction and reducing a parasitic capacitance generated between an impurity area and a word line by forming a trench in a portion of a semiconductor substrate and forming impurity areas around the trenches, include a semiconductor substrate, a plurality of trenches formed in the semiconductor substrate, first impurity areas formed along the outer surfaces of the plurality of trenches, second impurity areas formed on the bottom surfaces of the first impurity areas along the outer surfaces of the trenches, an insulating film filled in the trenches, a gate insulating film formed at a regular interval on the substrate having the insulating film filled in the trenches, and a gate electrode formed on the gate insulating film.

Abstract: Disclosed is a method of fabricating memory devices. By the method, a silicon nitride layer is used as a mask to form oxide layers on the lateral sides of the word lines through high-temperature heat treatment as source/drain annealing or oxidation. An etching process is subsequently used to remove the silicon nitride layer so as to expose the polysilicon layer on the word lines. After that, metal, preferably aluminum, is selectively grown the exposed polysilicon layer, which allows the resistance of the word lines to be significantly lowered thereby increasing access speed of the memory device.

Abstract: In a method of manufacturing a nonvolatile semiconductor memory device, a first polysilicon conductive layer, which is formed in a peripheral circuit region on a semiconductor substrate with a third gate insulating film interposed therebetween, is patterned into the shape of a gate electrode. A gate bird's beak is formed below the gate electrode in the peripheral circuit region by means of a heat treatment in an oxidizing atmosphere. Subsequently, in a memory cell array region, the first polysilicon conductive layer and a second polysilicon conductive layer laminated thereabove are processed to obtain a stacked gate structure.

Abstract: Methods and arrangements are provided for introducing nitrogen into a tunnel oxide layer within a stacked gate structure of a non-volatile memory cell. The nitrogen is advantageously introduced into only a select portion of the tunnel oxide, preferably nearer the source region of the memory cell. This prevents the unwanted or residual nitrogen from detrimentally affecting other devices within the semiconductor integrated circuit.

Abstract: A MOS device and method of fabricating the same, wherein the source/drain region has polysilicon trench structure which are formed by self-alignment using silicon oxide layers as masks. The source/drain regions extend to the field oxide layer and/or above the gate. Therefore, contacts can be formed on source/drain conductive regions above the field oxide layer.

Abstract: A patternless, self-aligning method of forming a floating gate on a silicon wafer having a plurality of raised field oxide isolation structures. The method of the present invention includes depositing a polysilicon layer onto the silicon wafer and the raised field oxide isolation structures, depositing a polysilicon etch masking layer onto the polysilicon layer, and planarizing the polysilicon etch masking layer. The polysilicon etch masking layer is then etched to expose the polysilicon layer over the raised field oxide isolation structures. The exposed polysilicon layer is then etched to remove the polysilicon layer over the raised field oxide isolation structures. The remaining polysilicon etch masking layer is then removed, leaving a plurality of polysilicon regions covering the silicon wafer between the field oxide isolation structures.

Abstract: A method for forming CMOS DRAM circuitry is disclosed and which includes forming a substrate comprising an array NMOS region, a peripheral NMOS region, and a peripheral PMOS region; forming a pair of insulated and spaced gate lines in the array NMOS region; forming at least one electrically conductive plug in the array NMOS region and which spans between the pair of gate lines; forming a barrier layer over the pair of gate lines in the array NMOS region, the peripheral NMOS and the peripheral PMOS region; and patterning and etching in the peripheral PMOS region to form peripheral PMOS region gate lines including removing a portion of the barrier layer in the PMOS peripheral region and leaving barrier layer material in the NMOS region masking over the electrically conductive plug.

Abstract: A fabrication process of a mask ROM is disclosed, which process is effective to suppress the occurrence of punch-through of a memory cell transistor. According to the process, the surface of a P conductivity-type silicon substrate is subjected to thermal oxidation to grow oxides to form a pad oxide film. A silicon nitride film, which acts as an oxidation resisting film, is deposited on the pad oxide film. A resist is formed on the silicon nitride film. The resist has openings where bit lines are to extend. Using the resist as a mask, the silicon nitride film is selectively etched away. Using the resist as a mask, ions of arsenic (As) are introduced by ion implantation to the substrate for formation of N conductivity-type diffusion regions in the subsequent thermal oxidation. These N conductivity-type diffusion regions act as the bit lines. Using the resist as a mask, ions of boron (B) are introduced by ion implantation for formation of P.sup.

Abstract: A method for fabricating a semiconductor device includes the steps of forming a field oxide layer on a first conductivity-type semiconductor substrate, and forming a pattern of first active regions. The field oxide layer is selectively removed between the first active regions to pattern a second active region and word lines are formed substantially perpendicular to each of the first active regions. A second conductivity-type impurity is implanted into the substrate using a mask to form impurity diffusion regions in the first and second active regions. A first insulating layer is formed over an overall surface of the substrate, and forming a first contact hole in the second active region. A bit line is formed for contacting with the impurity diffusion region on the second active region through the first contact hole.

Abstract: A method for forming oxides on buried N.sup.+ -type regions in a memory cell fabrication process, suitable for forming oxides on the bury N.sup.+ -type regions before self-aligned MOS device etching, comprises: (1) implanting a high concentration of impurity into the buried N.sup.+ -type regions; (2) annealing the chip; and (3) executing a dry oxide process and then a wet oxidation process to the chip, thereby preventing damage to the edges of buried N.sup.+ -type regions caused by non-uniform thickness of oxides on buried regions during self-aligned MOS etching and resolving the problem of non-uniform oxides on buried N.sup.+ -type regions.

Abstract: A method of making an EPROM transistor in a high density CMOS integrated circuit having a poly to poly capacitor and including two layers of polysilicon. The EPROM transistor is made using only the steps used to make the other components of the high density CMOS integrated circuit. The EPROM transistor is programmable at the low voltages which high density CMOS transistors can handle.

Abstract: This invention provides a cost-effective, easy-to-integrate Flash EPROM cell array. Starting with a substrate (31) of first conductivity-type, a first diffusion (30) of second conductivity-type forms the sources (11), and the connections between sources, of all of the memory cells (10) of the array. A second diffusion (32) of first conductivity-type forms the channel of at least one memory cell (10) in the array. A floating gate (13) and a control gate (14) of that memory cell (10) are located over, and insulated from, a junction of the first diffusion and the second diffusion. A third diffusion (33) of second conductivity-type is isolated in the second diffusion (32) to form the drain (12) of the memory cell (10). During operation, only positive voltages may be used for programming and erasing of the cells (10), thus eliminating the need for negative voltages and for triple-well diffusions. The cell array of this invention requires little or no current for Fowler-Nordheim erase operation.

Abstract: In a method of fabricating a DMOS transistor structure, wherein the DMOS transistor structure includes an active semiconductor substrate region having a tub of N-type conductivity formed therein, the N-type tub being formed over an N.sup.+ buried region, and having an N.sup.+ sinker region formed therein at an edge of the N-type tub, the N.sup.+ sinker region extending from a surface of the N-type tub to the N.sup.+ buried region, a pad oxide layer is formed on the N-tub and on the N.sup.+ sinker region. A composite mask is then formed on the silicon nitride layer, and includes etched openings such that the surface of the periphery of the N-type tub is exposed and the interface between the N-type tub and the N.sup.+ sinker region is exposed. The composite mask is then utilized to form field oxide isolation regions in the semiconductor substrate region at the periphery of the N-type tub and at the interface between the N-type tub and the N.sup.+ sinker region.

Abstract: A method for fabricating word lines of a semiconductor device, advantageous in that the word lines are easy to form, the process allowance for the neighboring patterns is sufficiently secured and thereby enhances the process yield and reliability of device operation. In an asymmetric memory unit cell structure having a T- or Z-shaped active region, the distortion of the word lines, attributable to the diffused reflection occurring at the boundary of an element isolation oxide film, is compensated by shifting the opposite word lines up and/or down a distance as long as the distortion is caused by the diffused reflection at the slant part of an active region. As a result, the center of the word line coincides with that of contact.

Abstract: Novel memory cells utilize source-side injection, allowing very small programming currents. If desired, to-be-programmed cells are programmed simultaneously while not requiring an unacceptably large programming current for any given programming operation. In one embodiment, memory arrays are organized in sectors with each sector being formed of a single column or a group of columns having their control gates connected in common. In one embodiment, a high speed shift register is used in place of a row decoder to serially shift in data for the word lines, with all data for each word line of a sector being contained in the shift register on completion of its serial loading. In one embodiment, speed is improved by utilizing a parallel loaded buffer register which receives parallel data from the high speed shift register and holds that data during the write operation, allowing the shift register to receive serial loaded data during the write operation for use in a subsequent write operation.

Abstract: A self-aligned planarization and isolation technique achieves smaller dimension memory cells using self-aligned isolation trenches. The process involves defining the lines of buried diffusion and first layer of polysilicon using a single mask. A protective oxide is formed between the polysilicon lines. Then a second mask is used with non-critical alignment to select polysilicon lines to define self-aligned etch regions. The trenches are made using a high selectivity etching recipe which etches through polysilicon and the silicon substrate in the selected lines faster than the protective oxide. Thus, a single mask defines the diffusion regions, the first layer of polysilicon, and the isolation trenches. The mask used for selecting polysilicon lines for definition of isolation structures does not need to be critically aligned, removing the alignment tolerance for formation of the isolation structures out of the layout of the array.