Patents by Inventor Rajiv V. Joshi
Rajiv V. Joshi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6337595Abstract: A low-voltage, low-power DC voltage generator system is provided having two negative voltage pump circuits for generating voltages for operating negative wordline and substrate bias charge pump circuits, a reference generator for generating a reference voltage, and a two-stage cascaded positive pump system having a first stage pump circuit and a second stage pump circuit. The first stage converts a supply voltage to a higher voltage level, e.g., one volt to 1.5 volts, to be used for I/O drivers, and the second stage converts the output voltage from the first stage to a higher voltage level, e.g., from 1.5 volts to about 2.5 volts, for operating a boost wordline charge pump circuit. The DC voltage generator system further includes a micro pump circuit for providing a voltage level which is greater than one-volt to be used as reference voltages, even when an operating voltage of the DC voltage generator system is at or near one-volt.Type: GrantFiled: July 28, 2000Date of Patent: January 8, 2002Assignee: International Business Machines CorporationInventors: Louis L. Hsu, Rajiv V. Joshi, Russell J. Houghton, Wayne F. Ellis, Jeffrey H. Dreibelbis
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Patent number: 6323554Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH4 to WF6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: July 10, 1998Date of Patent: November 27, 2001Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 6147402Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Superior conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH.sub.4 to WF.sub.6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: July 10, 1998Date of Patent: November 14, 2000Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 6034887Abstract: A magnetic tunneling junction cell for use in memory and logic switching applications is formed with a first ferromagnetic layer, a second ferromagnetic layer, and an insulating layer interposed between said first and second ferromagnetic layers to form a magnetic tunnel junction element. The cell further includes a write conductor which has a first conductor segment aligned in a first direction and located proximate to the first ferromagnetic layer and a second conductor segment aligned in a second direction, substantially orthogonal to the first direction and located proximate to the second ferromagnetic layer. The write conductor is terminated by a capacitive structure which allows a bidirectional current to be established in the write conductor using a monopolar write voltage and only a single port write terminal. The bidirectional current writes a high impedance state into the cell in a first current direction and a low impedance state into the cell in a second current direction.Type: GrantFiled: August 5, 1998Date of Patent: March 7, 2000Assignee: International Business Machines CorporationInventors: Arunava Gupta, Rajiv V. Joshi
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Patent number: 5976975Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the-hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Superior conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH.sub.4 to WF.sub.6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: July 10, 1998Date of Patent: November 2, 1999Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5889328Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Superior conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH.sub.4 to WF.sub.6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: December 3, 1996Date of Patent: March 30, 1999Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5617047Abstract: A single sequential timing chain provides inadequate precision of reset-pulse timing and inadequate reset-pulsewidth control for high-performance memories or register files incorporating dynamic circuits. Also, in such circuits, an inevitable lengthening of pulses, from input to output, ensues. These shortcomings are eliminated by the disclosed multiple-branch circuits, which provide for the generation of appropriate control pulses, and by employment of evaluation-path pulsewidth-shortening circuits appropriately interconnected to the control-generation circuits.Type: GrantFiled: June 6, 1995Date of Patent: April 1, 1997Assignee: International Business Machines CorporationInventors: Walter H. Henkels, Wei Hwang, Rajiv V. Joshi
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Patent number: 5585673Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Superior conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH.sub.4 to WF.sub.6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: November 22, 1994Date of Patent: December 17, 1996Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5525828Abstract: Silicon-VLSI-compatible photodetectors, in the form of a metal-semiconductor-metal photodetector (MSM-PD) or a lateral p-i-n photodetector (LPIN-PD), are disclosed embodying interdigitated metallic electrodes on a silicon surface. The electrodes of the MSM-PD have a moderate to high electron and hole barrier height to silicon, for forming the Schottky barriers, and are fabricated so as to be recessed in the surface semiconducting layer of silicon through the use of self-aligned metallization either by selective deposition or by selective reaction and etching, in a manner similar to the SALICIDE concept. Fabrication is begun by coating the exposed Si surface of a substrate with a transparent oxide film, such that the Si/oxide interface exhibits low surface recombination velocity.Type: GrantFiled: August 23, 1994Date of Patent: June 11, 1996Assignee: International Business Machines CorporationInventors: Ernest Bassous, Jean-Marc Halbout, Subramanian S. Iyer, Rajiv V. Joshi, Vijay P. Kesan, Michael R. Scheuermann, Massimo A. Ghioni
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Patent number: 5426330Abstract: A device includes a substrate, at least one dielectric layer positioned on said substrate, and metalization positioned in an opening in the at least one dielectric layer and extending a predetermined distance towards the substrate from a surface which is substantially coplanar with a surface of the at least one dielectric layer. The metalization includes a low resistivity metal or alloy encapsulated by a refractory metal or alloy having a resistivity greater than that of the low resistivity metal or alloy and having a columnar structure. The metalization has a plurality of sides in cross-section, at least three sides of the plurality of sides being substantially formed of a refractory metal or alloy having a common composition, at least two sides of the plurality of sides extending substantially the predetermined distance, and all of the plurality of sides being formed within the opening in the at least one dielectric layer.Type: GrantFiled: September 21, 1993Date of Patent: June 20, 1995Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5420069Abstract: The fabrication and use of corrosion resistant Cu/Cu(x)Ge(y) alloy or Cu/Cu.sub.3 Ge phase bilayer interconnect metal lines is disclosed. A solid state, selective process of forming a Cu.sub.3 Ge phase or Cu(x)Ge(y) alloy by reacting GeH.sub.4 gas with Cu surface at low pressure in CVD reactor at temperatures of 200.degree.-450.degree. C. is described. Corrosion resistant semiconductor devices and packaging interconnects where corrosion of copper interconnects was a problem, is now made possible by the Cu/Cu.sub.3 Ge phase or Cu.sub.x Ge.sub.y alloy bilayer of the present invention. A structure where copper vias are completely or partially converted to Cu.sub.3 Ge or Cu.sub.x Ge.sub.y is presented. Also, dissimilar metals like Al--Cu can be connected by Cu.sub.3 Ge phase or Cu.sub.x Ge.sub.y alloy filled vias to improve electromigration performance.Type: GrantFiled: December 31, 1992Date of Patent: May 30, 1995Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Manu J. Tejwani, Kris V. Srikrishnan
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Patent number: 5403779Abstract: Capping a low resistivity metal conductor line or via with a refractory metal allows for effectively using chemical-mechanical polishing techniques because the hard, reduced wear, properties of the refractory metal do not scratch, corrode, or smear during chemical-mechanical polishing. Superior conductive lines and vias are created using a combination of both physical vapor deposition (e.g., evaporation or collimated sputtering) of a low resistivity metal or alloy followed by chemical vapor deposition (CVD) of a refractory metal and subsequent planarization. Altering a ratio of SiH.sub.4 to WF.sub.6 during application of the refractory metal cap by CVD allows for controlled incorporation of silicon into the tungsten capping layer. Collimated sputtering allows for creating a refractory metal liner in an opening in a dielectric which is suitable as a diffusion barrier to copper based metalizations as well as CVD tungsten.Type: GrantFiled: August 12, 1992Date of Patent: April 4, 1995Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5391510Abstract: A sub-micron FET is disclosed made by a method using expendable self-aligned gate structure up to and including the step of annealing the source/drain regions. The source/drain regions are formed by ion implantation using the expendable structure (diamond-like-carbon) as a mask. After the expendable structure has performed its further purpose of protecting the gate dielectric from contamination during the annealing cycle, the structure is easily removed by O.sub.2 plasma and replaced by a conventional metal gate material.Type: GrantFiled: April 7, 1994Date of Patent: February 21, 1995Assignee: International Business Machines CorporationInventors: Louis L. Hsu, Gangadhara S. Mathad, Rajiv V. Joshi
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Patent number: 5382832Abstract: A wafer structure suitable for the formation of semiconductor devices thereon and having a buried interconnect structure for interconnection of desired ones of the semiconductor devices according to a predetermined interconnection pattern and a method of making the same is disclosed. The wafer structure comprises a primary substrate having a first thickness appropriate for the formation of the desired semiconductor devices.Type: GrantFiled: October 4, 1993Date of Patent: January 17, 1995Assignee: International Business Machines CorporationInventors: Taqi N. Buti, Louis L. Hsu, Rajiv V. Joshi, Joseph F. Shepard
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Patent number: 5300813Abstract: A contact structure for a semiconductor device having a first refractory metal layer formed only at the bottom of a contact hole. The first refractory metal is selected from a group comprising titanium (Ti), titanium alloys or compounds such as Ti/TiN, tungsten (W), titanium/tungsten (Ti/W) alloys, or chromium (Cr) or tantalum (Ta) and their alloys or some other suitable material. A low resistivity layer comprising a single, binary or ternary metalization is deposited over the first refractory metal layer in the contact hole by a method such as PVD using evaporation or collimated sputtering. The low resistivity layer has side walls which taper inwardly toward one another with increasing height of the layer and the low resistivity layer does not contact the side walls of the contact hole. The low resistivity layer may be Al.sub.x Cu.sub.y (x+y=1; x.gtoreq.0, y.gtoreq.0), ternary alloys such as Al-Pd-Cu or multicomponent alloys such as Al-Pd-Nb-Au.Type: GrantFiled: February 26, 1992Date of Patent: April 5, 1994Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Jerome J. Cuomo, Hormazdyar M. Dalal, Louis L. Hsu
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Patent number: 5260233Abstract: A wafer structure suitable for the formation of semiconductor devices thereon and having a buried interconnect structure for interconnection of desired ones of the semiconductor devices according to a predetermined interconnection pattern and a method of making the same is disclosed. The wafer structure comprises a primary substrate having a first thickness appropriate for the formation of the desired semiconductor devices.Type: GrantFiled: November 6, 1992Date of Patent: November 9, 1993Assignee: International Business Machines CorporationInventors: Taqi N. Buti, Louis L-C. Hsu, Rajiv V. Joshi, Joseph F. Shepard
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Patent number: 5221853Abstract: Selective deposition of a refractory metal on a silicon substrate utilizing high temperatures and a silane reduction process in which the flow rate ratio of silane to refractory metal halide gas is less than one. In a second embodiment, an additional layer of the refractory metal is deposited utilizing a hydrogen reduction of the metal halide gas at very high temperatures. In both embodiments, a refractory metal barrier layer may be provided by forming a self-aligned refractory metal silicide layer. Alternatively, a two layer self-aligned barrier is formed of a refractory metal silicide lower layer and a refractory metal nitride upper layer and the refractory metal is selectively deposited on the metal nitride.Type: GrantFiled: September 20, 1991Date of Patent: June 22, 1993Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Choon-Sik Oh, Dan Moy
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Patent number: 5212400Abstract: A method of depositing tungsten on a substrate utilizing silicon reduction wherein the process is non-limiting as to the thickness of silicon that may be converted to tungsten. A silicon substrate is provided with at least one area of silicon material having a predetermined thickness and the substrate is exposed to a tungsten hexafluoride gas flow in a chemical vapor deposition environment. By adjusting the WF.sub.6 gas flow rate and the CVD process parameters, such as pressure, temperature and deposition time, the thickness of silicon converted to tungsten can be adjusted in order to convert the entire thickness. A novel structure having a midgap tungsten gate and tungsten source and drain metallized layers is also disclosed.Type: GrantFiled: September 3, 1991Date of Patent: May 18, 1993Assignee: International Business Machines CorporationInventor: Rajiv V. Joshi
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Patent number: 5202287Abstract: Selective deposition of a refractory metal on a silicon substrate utilizing high temperatures and a silane reduction process in which the flow rate ratio of silane to refractory metal halide gas is less than one. In a second embodiment, an additional layer of the refractory metal is deposited utilizing a hydrogen reduction of the metal halide gas at very high temperatures. In both embodiments, a refractory metal barrier layer may be provided by forming a self-aligned refractory metal silicide layer. Alternatively, a two layer self-aligned barrier is formed of a refractory metal silicide lower layer and a refractory metal nitride upper layer and the refractory metal is selectively deposited on the metal nitride.Type: GrantFiled: January 6, 1992Date of Patent: April 13, 1993Assignee: International Business Machines CorporationInventors: Rajiv V. Joshi, Choon-Sik Oh, Dan Moy
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Patent number: 5086016Abstract: A contact is provided in a self-aligned manner to a doped region a semiconductor substrate by first forming a layer of a transition metal-boride compound over a selected region on the substrate. A layer of a transition metal-nitride compound is formed over the layer of transition metal-boride compound, and the structure is heated to drive dopant from the layer of transition metal-boride compound into the substrate. The transition metal-boride/transition metal nitride layers are patterned to leave a contact to the doped region.Type: GrantFiled: October 31, 1990Date of Patent: February 4, 1992Assignee: International Business Machines CorporationInventors: Stephen B. Brodsky, Rajiv V. Joshi, John S. Lechaton, James G. Ryan, Dominic J. Schepis