Abstract: A strip of a semiconductor material (for example, P type silicon) is oxidized and the resulting strip of oxide is removed leaving a depression in the upper surface of the semiconductor material which has steep sidewalls. The steep sidewalls do not have significant ion impact damage because they are formed by oxidation and not by reactive ion etching of the semiconductor material. A high quality tunnel oxide can therefore be grown on the steep sidewalls. Floating gates are then formed on the tunnel oxide, corresponding word lines are formed over the floating gates, a conductive region (for example, N type silicon) is formed into the bottom of the depression, and a number of conductive regions (for example, N type silicon) corresponding with the floating gates are formed above the rim of the depression. The resulting bit transistors have channel regions which extend in a vertical dimension under floating gates along the surface of the sidewall.

Abstract: A wet etching process for establishing isolation grooves in a flash memory core wafer includes depositing nitride and/or oxide layers on a silicon substrate of the wafer, depositing a photoresist layer thereon, and then exposing predetermined portions of the photoresist layer to ultraviolet light to establish a desired groove pattern in the photoresist layer. A dry etching process is then used to remove the nitride and/or oxide layers beneath the groove pattern of the photoresist layer to thereby expose portions of the substrate. Next, the wafer is disposed in a wet etching solution such as potassium hydroxide to form grooves in the exposed portions of the silicon substrate. The wafer is oriented and disposed in the bath as appropriate for forming V-shaped grooves, such that after etching, the angled walls of the grooves can be easily exposed to a dopant beam directly above the wafer, without having to tilt the wafer or beam source. Thereby, the walls of the grooves are easily implanted with dopant.

Abstract: The present invention provides a method of etching microelectronic structures. The method utilizes an ion implantation device projecting ions into a silicon semiconductor or conducting substrate to selectively damage the surface causing damage differential. This process is highly controllable and directable, allowing fine manipulation of the substrate surface. After the ion implantation has destroyed selected portions of the surface, standard etching techniques known in the art can be used to selectively remove the damaged portions of the surface. The advantage of this technique is that it confers upon relatively imprecise prior art etching techniques a high degree of precision. Such techniques can be used to create isolation trenches by filling the surface with electrically isolating materials which isolate one semiconductor device from another.

Abstract: Apparatus and methods for determining the robustness of a device to soft errors generated by alpha-particle and/or cosmic ray strikes. In one embodiment, the method includes the steps of producing a light pulse having a light pulse energy, applying the light pulse to the device at a predetermined location, varying the light pulse energy, and detecting soft errors in the device. In another embodiment, the apparatus includes a light source for producing a light pulse that is applied to the device at a predetermined location, a light pulse energy varying circuit coupled to the light source and configured to vary the light energy of the light pulse, and a detecting circuit coupled to the device and configured to detecting soft errors in the device.

Abstract: A non-volatile semiconductor cell structure and method comprises a trenched floating gate, a sidewall doping and a corner doping and further includes a sidewall doped region, a corner doped region, a channel region, and an inter-gate dielectric layer, and a control gate. The trenched floating gate is formed in a trench etched into the semiconductor substrate. In a preferred embodiment, the trenched floating gate has a top surface which is substantially planar with a top surface of the semiconductor substrate. The control gate and the inter-gate dielectric are formed on the top surface of the trenched floating gate. The sidewall doped region and the corner doped region are laterally separated by the trench in which the trenched floating gate is formed. The sidewall doped region has a depth which is greater than the depth of the trench, and the corner doped region has a depth which is less than the depth of the trench.

Abstract: A method for making a self-aligned isolated flash memory core without damaging tunnel oxide layers between memory element stacks and the silicon substrate supporting the stacks includes depositing three sidewall layers on the stacks, prior to etching isolation trenches between the stacks, to thereby shield the tunnel oxide during isolation trench etching.

Abstract: A novel semiconductor fabrication process having the advantages of conventional LOCOS (process simplicity and reduced defects) while providing a scaleable, planar isolation region between active regions formed in a semiconductor substrate. The preferred process includes formation of a barrier layer and a masking layer over the substrate. An active region mask defines an exposure region of the masking layer. The exposure region is etched to form an opening, exposing a portion of barrier layer in the opening. A spacer is added inside the opening, around a perimeter of the opening to define a second exposure region. The barrier layer, and substrate, under the second exposure region, but not under the spacer, are etched to form an isolation region opening. The isolation region opening may have a suitable isolating material, such as silicon oxide, grown, filled, or some combination of both, in the isolation region opening.

Abstract: A semiconductor device having the advantages of an SOI structure without the attendant disadvantages is obtained by implanting oxygen ions using the gate electrode as a mask, and heating to form thin, self-aligned buried oxide regions extending from a field oxide region under source/drain regions self-aligned with the side surfaces of the gate electrode. In other embodiments, the thin buried oxide layer extends from a point in close proximity to the field oxide region and/or partially under the gate electrode.

Abstract: A strip of a semiconductor material (for example, P type silicon) is oxidized and the resulting strip of oxide is removed leaving a depression in the upper surface of the semiconductor material which has steep sidewalls. The steep sidewalls do not have significant ion impact damage because they are formed by oxidation and not by reactive ion etching of the semiconductor material. A high quality tunnel oxide can therefore be grown on the steep sidewalls. Floating gates are then formed on the tunnel oxide, corresponding word lines are formed over the floating gates, a conductive region (for example, N type silicon) is formed into the bottom of the depression, and a number of conductive regions (for example, N type silicon) corresponding with the floating gates are formed above the rim of the depression. The resulting bit transistors have channel regions which extend in a vertical dimension under floating gates along the surface of the sidewall.

Abstract: A method for fabricating a semiconductor device including a silicon substrate and plural silicon stacks thereon includes forming a nitride shield layer on the substrate and stacks to cover the stacks, such that the stacks are protected from loss of critical dimension during subsequent isolation trench formation and oxidation. In other words, the edge of each stack, and thus the critical dimension of the silicon layers of the stack, is protected from oxidation by the nitride shield layer.

Abstract: A field effect transistor is formed across one or more trenches (26) or bars (120), thereby increasing the effective width of the channel region and the current-carrying capacity of the device.

Abstract: A field effect transistor has a short gate and is fabricated by: doping the bottom surface of a depression to form a relatively lightly doped region in the bottom of the depression; forming the gate of the field effect transistor on the sidewall of the depression such that the gate is insulated from the sidewall by a thin insulating layer; and implanting dopants to form the drain region and the source region of the transistor using the gate to mask a part of the relatively lightly doped region. The part of the relatively lightly doped region which is masked by the gate during implanting of the source and drain regions constitutes a lightly doped drain region of the transistor. The drain of the transistor is formed into the bottom of the depression. The length of the gate is primarily determined by the depth and/or profile of the sidewall. The source-to-drain on-resistance of the transistor is low because the transistor does not have a lightly doped source region.

Abstract: Floating gates of nonvolatile memory cells are formed in pairs within a pyramidal or truncated pyramidal opening in a semiconductor layer between a top surface thereof and a heavily doped source region spaced from the surface of the semiconductor layer. The floating gates control the conductance of channel regions formed along the sloped sidewalls of the pyramidal openings between surface drains and the buried source region.

Abstract: A static metal oxide semiconductor random access memory (SRAM) having NMOS and thin film transistors (TFTs) formed from a single polysilicon layer, and a method for forming the same. The SRAM cell comprises a plurality of NMOS transistors and TFTs that are interconnected by a local interconnect structure. The single layer of poly is used to define the TFT bodies and gates of NMOS transistors in the SRAM cell. Each TFT comprises a single polysilicon layer comprising source gate and drain regions. During the fabrication process, exposed portions of the TFT polysilicon body and exposed regions of NMOS transistors react with a refractory metal silicide to form polycide and silicide regions, respectively. An amorphous silicon pattern also reacts with the refractory metal silicide to form a local interconnect structure connecting the silicided portions of the thin film transistors and the MOS transistors.

Abstract: A novel MOS transistor structure for improving device scaling by improving short channel control includes a buried back gate beneath a channel region of the MOS transistor. A separate contact to a well that is electrically communicated to the buried back gate improves short channel controls without performance degradations. In a preferred embodiment, the back gate is grounded when turning the n-channel MOS transistor off. In alternate embodiments, the buried layer produces retrograde p wells. In some applications, multiple buried layers may be used, with one or more being planar. CMOS devices may have independent, multiple buried back gates.

Abstract: CMOS transistors are formed by a damascene process resulting in field oxide regions exhibiting essentially no bird's beak portions. A trench isolation is also formed in a source/drain region each transistor between adjacent junctions.

Abstract: Complementary metal-oxide-semiconductor (CMOS) transistors (18,22) are formed with vertical channel regions (30,52) on an insulator substrate (14). Highly doped polysilicon gates (44,68) are formed in trenches (36,58) to extend laterally around the channel regions (30,52) as insulatively displaced therefrom by gate insulators (41,62) that are grown on the sidewalls of the trenches (36,58). The transistors (18,22), which are formed in respective mesas (20,24) have deeply implanted source regions (28,50) that are ohmically connected to the semiconductor surface via respective source connector regions (34,70).

Abstract: A metal oxide semiconductor static random access memory (SRAM) includes NMOS transistors and resistor structures implemented without multiple polysilicon layers. According to a first embodiment, the SRAM cell comprises a plurality of appropriately interconnected NMOS transistors having transistor gates formed of a polysilicon layer and resistors formed of the same polysilicon layer. In accordance with a second embodiment, the SRAM cell comprises a plurality of appropriately interconnected NMOS transistors, a dielectric layer overlying the NMOS transistors, and polysilicon resistors passing through the dielectric layer to connect the NMOS transistors to a first metal layer. The dielectric layer, deposited on the NMOS transistors, defines holes exposing drain regions in the NMOS transistors. A polysilicon layer is deposited on the dielectric layer to fill the holes, and the excess polysilicon is removed.

Abstract: A method of manufacturing a transistor having LDD regions in which the source and drain regions are formed by implanting ions through a photoresist layer at an energy of 1 MeV and greater and the LDD regions are formed by low energy ion implantation after the oxide layer is removed from the active region and the gate. In a second embodiment, the source and drain regions are formed without a photoresist layer by ion implantation and the LDD regions are formed by low energy ion implantation after the oxide layer is removed from the active region and the gate.

Abstract: A method of fabricating an integrated circuit with trenches, without parasitic edge transistors, for isolating FET transistors from each other without degrading the FETs operating characteristics by junction leakage, breakdown or shorting when a metal silicide is used in the source/drain regions. A silicon wafer, is formed with a gate electrode material on a gate insulating layer before forming the trenches for isolation. Now, with an etch protective layer on the gate electrode, trenches are etched and filled with an insulating material in the gate electrode material, the gate insulating layer and the silicon wafer to isolate the active regions. After the gate electrode material is etched to define the gate electrodes, the tops of gate electrodes are in essentially the same plane as the tops of the trenches. Preferably in the fabrication process, sidewalls are formed on the walls of the trenches and the gate electrodes.