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Ajith Varghese

Ajith Varghese, Austin, TX US

Patent application numberDescriptionPublished
20080217703HIGHLY SELECTIVE LINERS FOR SEMICONDUCTOR FABRICATION - A method for manufacturing an isolation structure is disclosed that protects the isolation structure during etching of a dichlorosilane (DCS) nitride layer. The method involves the formation of a bis-(t-butylamino)silane-based nitride liner layer within the isolation trench, which exhibits a five-fold greater resistance to nitride etching solutions as compared with DCS nitride, thereby allowing protection against damage from unintended over-etching. The bis-(t-butylamino)silane-based nitride layer also exerts a greater tensile strain on moat regions that results in heightened carrier mobility of active regions, thereby increasing the performance of NMOS transistors embedded therein.09-11-2008
20090045472Methodology for Reducing Post Burn-In Vmin Drift - A semiconductor device includes source/drain regions formed in a substrate and having a concentration of nitrogen of at least about 5E18 cm02-19-2009
20100032727BORDER REGION DEFECT REDUCTION IN HYBRID ORIENTATION TECHNOLOGY (HOT) DIRECT SILICON BONDED (DSB) SUBSTRATES - Hybrid orientation technology (HOT) substrates for CMOS ICs include (100)-oriented silicon regions for NMOS and (110) regions for PMOS for optimizing carrier mobilities in the respective MOS transistors. Boundary regions between (100) and (110) regions must be sufficiently narrow to support high gate densities and SRAM cells. This invention provides a method of forming a HOT substrate containing regions with two different silicon crystal lattice orientations, with boundary morphology less than 40 nanometers wide. Starting with a direct silicon bonded (DSB) wafer of a (100) substrate wafer and a (110) DBS layer, NMOS regions in the DSB layer are amorphized by a double implant and recrystallized on a (100) orientation by solid phase epitaxy (SPE). Crystal defects during anneal are prevented by a low temperature oxide layer on the top surface of the wafer. An integrated circuit formed with the inventive method is also disclosed.02-11-2010

Patent applications by Ajith Varghese, Austin, TX US

Ajith Varghese, Mckinney, TX US

Patent application numberDescriptionPublished
20080230815Mitigation of gate to contact capacitance in CMOS flow - Sidewall spacers that are primarily oxide, instead of nitride, are formed adjacent to a gate stack of a CMOS transistor. Individual sidewall spacers are situated between a conductive gate electrode of the gate stack and a conductive contact of the transistor. As such, a capacitance can develop between the gate electrode and the contact, depending on the dielectric constant of the interposed sidewall spacer. Accordingly, forming sidewall spacers out of oxide, which has a lower dielectric constant than nitride, mitigates capacitance that can otherwise develop between these features. Such capacitance is undesirable, at least, because it can inhibit transistor switching speeds. Accordingly, fashioning sidewall spacers as described herein can mitigate yield loss by reducing the number of devices that have unsatisfactory switching speeds and/or other undesirable performance characteristics.09-25-2008
20080251864STACKED POLY STRUCTURE TO REDUCE THE POLY PARTICLE COUNT IN ADVANCED CMOS TECHNOLOGY - A method for implementing a stacked gate, comprising forming a gate dielectric on a semiconductor body, forming a first layer of gate electrode material on the gate dielectric, forming a second layer of gate electrode material on the first layer of gate electrode material, wherein the grain size distribution of the first layer of gate electrode material is different than the grain size distribution of the second layer of gate electrode material, implanting the first and second gate electrode materials, patterning the first and the second gate electrodes and the gate dielectric, and forming source and drain regions.10-16-2008
20080268603TRANSISTOR PERFORMANCE USING A TWO-STEP DAMAGE ANNEAL - A two-step thermal treatment method consists of performing ion implantation in a silicon substrate of the semiconductor device. A first thermal treatment procedure is performed on the semiconductor device. A second thermal treatment procedure is consecutively performed on the semiconductor device to reduce damage produced by the ion implantation.10-30-2008
20080268627TRANSISTOR PERFORMANCE USING A TWO-STEP DAMAGE ANNEAL - A two-step thermal treatment method consists of performing ion implantation in a silicon substrate of the semiconductor device. A first thermal treatment procedure is performed on the semiconductor device. A second thermal treatment procedure is consecutively performed on the semiconductor device to reduce damage produced by the ion implantation.10-30-2008
20080315324METHOD TO OBTAIN UNIFORM NITROGEN PROFILE IN GATE DIELECTRICS - The present invention, in one aspect, provides a method of manufacturing a microelectronics device 12-25-2008
20090170346LOW TEMPERATURE POLYSILICON OXIDE PROCESS FOR HIGH-K DIELECTRIC/METAL GATE STACK - A method for preventing oxidation in a high-k dielectric/metal gate stack in the manufacture of an integrated circuit device is disclosed. In a detailed embodiment, a PMOS region stack has nitrided hafnium silicide, tungsten, tantalum nitride and polysilicon layers. An NMOS region stack has nitrided hafnium silicide, tungsten silicide, tantalum nitride and polysilicon layers. A thin polysilicon layer deposited over the stacks is converted to an oxide using a low temperature ultraviolet ozone oxidation process or a plasma nitridation using decoupled plasma nitridation or NH07-02-2009

Patent applications by Ajith Varghese, Mckinney, TX US

Ajith Varghese, Mckinnery, TX US

Patent application numberDescriptionPublished
20080246099LOW TEMPERATURE POLY OXIDE PROCESSES FOR HIGH-K/METAL GATE FLOW - An integrated circuit device is disclosed as comprising a feature that is susceptible to oxidation. A poly-oxide coating is used over the feature susceptible to oxidation to protect the feature susceptible to oxidation from oxidizing. Various method can be used to form the poly-oxide coating include conversion of a ploy-silicon coating using UV O10-09-2008