Patents by Inventor Atul C. Ajmera
Atul C. Ajmera 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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Publication number: 20130256766Abstract: Process for enhancing strain in a channel with a stress liner, spacer, process for forming integrated circuit and integrated circuit. A first spacer composed of a first oxide and first nitride layer is applied to a gate electrode on a substrate, and a second spacer composed of a second oxide and second nitride layer is applied. Deep implanting of source and drain in the substrate occurs, and removal of the second nitride, second oxide, and first nitride layers.Type: ApplicationFiled: May 20, 2013Publication date: October 3, 2013Applicant: International Business Machines CorporationInventors: Atul C. AJMERA, Christopher V. BAIOCCO, Xiangdong CHEN, Wenzhi GAO, Young W. TEH
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Patent number: 8461009Abstract: Process for enhancing strain in a channel with a stress liner, spacer, process for forming integrated circuit and integrated circuit. A first spacer composed of an first oxide and first nitride layer is applied to a gate electrode on a substrate, and a second spacer composed of a second oxide and second nitride layer is applied. Deep implanting of source and drain in the substrate occurs, and removal of the second nitride, second oxide, and first nitride layers.Type: GrantFiled: February 28, 2006Date of Patent: June 11, 2013Assignees: International Business Machines Corporation, Chartered Semiconductor Manufacturing Ltd.Inventors: Atul C. Ajmera, Christopher V. Baiocco, Xiangdong Chen, Wenzhi Gao, Young Way Teh
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Patent number: 7759206Abstract: A method of forming a semiconductor device that embeds an L-shaped spacer is provided. The method includes defining an L-shaped spacer on each side of a gate region of a substrate and embedding the L-shaped spacers in an oxide layer so that the oxide layer extends over a portion of the substrate a predetermined distance from a lateral edge of the L-shaped spacer. And removing oxide layers to expose the L-shape spacers.Type: GrantFiled: November 29, 2005Date of Patent: July 20, 2010Assignees: International Business Machines Corporation, Chartered Semiconductor Manufacturing Ltd.Inventors: Zhijiong Luo, Young Way Teh, Atul C. Ajmera
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Patent number: 7091128Abstract: A method for forming a CMOS device in a manner so as to avoid dielectric layer undercut during a pre-silicide cleaning step is described. During formation of CMOS device comprising a gate stack on a semiconductor substrate surface, the patterned gate stack including gate dielectric below a conductor with vertical sidewalls, a dielectric layer is formed thereover and over the substrate surfaces. Respective nitride spacer elements overlying the dielectric layer are formed at each vertical sidewall. The dielectric layer on the substrate surface is removed using an etch process such that a portion of the dielectric layer underlying each spacer remains. Then, a nitride layer is deposited over the entire sample (the gate stack, the spacer elements at each gate sidewall, and substrate surfaces) and subsequently removed by an etch process such that only a portion of said nitride film (the “plug”) remains.Type: GrantFiled: November 4, 2005Date of Patent: August 15, 2006Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Andres Bryant, Percy V. Gilbert, Michael A. Gribelyuk, Edward P. Maciejewski, Renee T. Mo, Shreesh Narasimha
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Patent number: 6991979Abstract: A method for forming a CMOS device in a manner so as to avoid dielectric layer undercut during a pre-silicide cleaning step is described. During formation of CMOS device comprising a gate stack on a semiconductor substrate surface, the patterned gate stack including gate dielectric below a conductor with vertical sidewalls, a dielectric layer is formed thereover and over the substrate surfaces. Respective nitride spacer elements overlying the dielectric layer are formed at each vertical sidewall. The dielectric layer on the substrate surface is removed using an etch process such that a portion of the dielectric layer underlying each spacer remains. Then, a nitride layer is deposited over the entire sample (the gate stack, the spacer elements at each gate sidewall, and substrate surfaces) and subsequently removed by an etch process such that only a portion of said nitride film (the “plug”) remains.Type: GrantFiled: September 22, 2003Date of Patent: January 31, 2006Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Andres Bryant, Percy V. Gilbert, Michael A Gribelyuk, Edward P. Maciejewski, Renee T. Mo, Shreesh Narasimha
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Patent number: 6900092Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.Type: GrantFiled: June 27, 2002Date of Patent: May 31, 2005Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
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Patent number: 6642156Abstract: A method for forming an ultra thin gate dielectric for an integrated circuit device is disclosed. In an exemplary embodiment of the invention, the method includes forming an initial nitride layer upon a substrate by rapidly heating the substrate in the presence of an ammonia (NH3) gas, and then re-oxidizing the initial nitride layer by rapidly heating the initial nitride layer in the presence of a nitric oxide (NO) gas, thereby forming an oxynitride layer. The oxynitride layer has a nitrogen concentration therein of at about 1.0×1015 atoms/cm2 to about 6.0×1015 atoms/cm2, and has a thickness which may be controlled within a sub 10 Å range.Type: GrantFiled: August 1, 2001Date of Patent: November 4, 2003Assignee: International Business Machines CorporationInventors: Evgeni Gousev, Atul C. Ajmera, Christopher P. D'Emic
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Patent number: 6605521Abstract: In order to prevent abnormal oxidation of the side wall of a polycide gate conductor layer in the oxidation heat treatment process after the RIE processing of the polycide gate conductor layer in a semiconductor memory cell, the heat treatment for oxidizing the side wall of the polycide gate conductor layer is conducted in two steps with different conditions. By conducting the first heat treatment process in an inert atmosphere, a thin oxide film is formed on the side wall of the polycide tungsten/gate conductor layer. Then by conducting the second heat treatment process in an atmosphere with a strong oxidizing property, a thick oxide film without abnormal oxidation can be formed.Type: GrantFiled: October 8, 2002Date of Patent: August 12, 2003Assignees: Kabushiki Kaisha Toshiba, International Business Machines CorporationInventors: Atul C. Ajmera, Karanam Balasubramanyam, Tomio Katata, Shang-Bin Ko
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Patent number: 6602759Abstract: A method for forming an isolation trench in a silicon or silicon-on-insulator substrate is described in which a trench is formed in the semiconductor structure (containing a multiple layer structure of Si, SiO2, and SiN layers) and an undoped polysilicon layer is deposited on the bottom and sidewalls of the trench and on the surface of the region adjacent to the trench. A substantial portion of the trench is left unfilled by the undoped polysilicon layer deposited. The polysilicon layer is thermally oxidized to form a thermal oxide that fills the trench and thereby avoids forming a birds-beak formation of the thermal oxide above the sidewalls of the trench. The isolation structure may be planarized by either removing the polysilicon layer from the region adjacent to the trench before oxidation or later removing the oxide from the SiN layer and adjusting height of the oxide in the trench.Type: GrantFiled: December 7, 2000Date of Patent: August 5, 2003Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Klaus D. Beyer, Dominic J. Schepis
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Patent number: 6566210Abstract: The present invention provides a method of preparing a Si-based metal-insulator-semiconductor (MIS) transistor which prevents the polycrystalline grains of the gate conductor from getting significantly larger by reducing the thermal budget of the sidewall oxidation process. The thermal budget of the inventive sidewall oxidation process is reduced one or two orders of magnitude over conventional prior art sidewall oxidation processes by utilizing atomic oxygen as the oxidizing ambient. The present invention also provides Si-based MIS transistors having a gate conductor having grain sizes of about 0.1, preferably 0.05, &mgr;m or less.Type: GrantFiled: July 13, 2001Date of Patent: May 20, 2003Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Omer H. Dokumaci, Bruce B. Doris, Oleg Gluschenkov
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Patent number: 6566198Abstract: A CMOS structure and method of achieving self-aligned raised source/drain for CMOS structures on SOI without relying on selective epitaxial growth of silicon. In the method, CMOS structures are provided by performing sacrificial oxidation so that oxidation occurs on the surface of both the SOI and BOX interface. This allows for oxide spacer formation for gate-to-source/drain isolation which makes possible raised source/drain fabrication without increasing contact resistance.Type: GrantFiled: March 29, 2001Date of Patent: May 20, 2003Assignee: International Business Machines CorporationInventors: Heemyong Park, Fariborz Assaderaghi, Atul C. Ajmera, Ghavam G. Shahidi
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Publication number: 20030036253Abstract: In order to prevent abnormal oxidation of the side wall of a polycide gate conductor layer in the oxidation heat treatment process after the RIE processing of the polycide gate conductor layer in a semiconductor memory cell, the heat treatment for oxidizing the side wall of the polycide gate conductor layer is conducted in two steps with different conditions. By conducting the first heat treatment process in an inert atmosphere, a thin oxide film is formed on the side wall of the polycide tungsten/gate conductor layer. Then by conducting the second heat treatment process in an atmosphere with a strong oxidizing property, a thick oxide film without abnormal oxidation can be formed.Type: ApplicationFiled: October 8, 2002Publication date: February 20, 2003Applicant: Kabushiki Kaisha ToshibaInventors: Atul C. Ajmera, Karanam Balasubramanyam, Tomio Katata, Shang-Bin Ko
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Publication number: 20030027392Abstract: A method for forming an ultra thin gate dielectric for an integrated circuit device is disclosed. In an exemplary embodiment of the invention, the method includes forming an initial nitride layer upon a substrate by rapidly heating the substrate in the presence of an ammonia (NH3) gas, and then re-oxidizing the initial nitride layer by rapidly heating the initial nitride layer in the presence of a nitric oxide (NO) gas, thereby forming an oxynitride layer. The oxynitride layer has a nitrogen concentration therein of at about 1.0×1015 atoms/cm2 to about 6.0×1015 atoms/cm2, and has a thickness which may be controlled within a sub 10 Å range.Type: ApplicationFiled: August 1, 2001Publication date: February 6, 2003Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Evgeni Gousev, Atul C. Ajmera, Christopher P. D'Emic
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Publication number: 20030010972Abstract: The present invention provides a method of preparing a Si-based metal-insulator-semiconductor (MIS) transistor which prevents the polycrystalline grains of the gate conductor from getting significantly larger by reducing the thermal budget of the sidewall oxidation process. The thermal budget of the inventive sidewall oxidation process is reduced one or two orders of magnitude over conventional prior art sidewall oxidation processes by utilizing atomic oxygen as the oxidizing ambient. The present invention also provides Si-based MIS transistors having a gate conductor having grain sizes of about 0.1, preferably 0.05, &mgr;m or less.Type: ApplicationFiled: July 13, 2001Publication date: January 16, 2003Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Atul C. Ajmera, Omer H. Dokumaci, Bruce B. Doris, Oleg Gluschenkov
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Patent number: 6506649Abstract: An innovative MOSFET having a raised source drain (RSD) is constructed prior to implanting source-drain dopants. The RSD structure thus built has a distinct advantage in that the offset from the RSD to the MOSFET channel is fully adjustable to minimize the overlap capacitance in the device. The RSD construction uses a selective epitaxial process to effectively reduce the drain-source resistance. This improvement is even more significant in thin-film SOI technology. Using an RSD, the film outside the channel area thickens which, in turn, reduces the parasitic resistance.Type: GrantFiled: March 19, 2001Date of Patent: January 14, 2003Assignee: International Business Machines CorporationInventors: Ka Hing Fung, Atul C. Ajmera, Victor Ku, Dominic J. Schepis
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Publication number: 20020192888Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.Type: ApplicationFiled: June 27, 2002Publication date: December 19, 2002Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
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Publication number: 20020142551Abstract: A CMOS structure and method of achieving self-aligned raised source/drain for CMOS structures on SOI without relying on selective epitaxial growth of silicon. In the method, CMOS structures are provided by performing sacraficial oxidation so that oxidation occurs on the surface of both the SOI and BOX interface. This allows for oxide spacer formation for gate-to-source/drain isolation which makes raised source/drain fabrication without increasing contact resistance possible.Type: ApplicationFiled: March 29, 2001Publication date: October 3, 2002Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Heemyong Park, Fariborz Assaderaghi, Atul C. Ajmera, Ghavam G. Shahidi
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Publication number: 20020132431Abstract: An innovative MOSFET having a raised source drain (RSD) is constructed prior to implanting source-drain dopants. The RSD structure thus built has a distinct advantage in that the offset from the RSD to the MOSFET channel is fully adjustable to minimize the overlap capacitance in the device. The RSD construction uses a selective epitaxial process to effectively reduce the drain-source resistance. This improvement is even more significant in thin-film SOI technology. Using an RSD, the film outside the channel area thickens which, in turn, reduces the parasitic resistance.Type: ApplicationFiled: March 19, 2001Publication date: September 19, 2002Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATIONInventors: Ka Hing Fung, Atul C. Ajmera, Victor Ku, Dominic J. Schepis
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Patent number: 6440807Abstract: The present invention provides a method of formed a nitrided surface layer atop a polysilicon gate electrode that inhibits the growth of an epi silicon layer thereon. Specifically, the method of the present invention includes the steps of: forming a polysilicon layer atop a gate dielectric layer, forming a nitrided surface layer on the polysilicon layer; selectively removing portions of the nitrided surface layer and the polysilicon layer stopping on the gate dielectric layer, while leaving a patterned stack of the nitrided surface layer and the polysilicon layer on the gate dielectric layer; forming sidewall spacers on at least exposed vertical sidewalls of polysilicon layer; removing portions of the gate dielectric layer not protected by the sidewall spacers; and growing an epi silicon layer on exposed horizontal surfaces of an underlying semiconductor substrate.Type: GrantFiled: June 15, 2001Date of Patent: August 27, 2002Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Dominic J. Schepis, Michael D. Steigerwalt
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Patent number: 6437377Abstract: A notched gate MOS device includes either an encapsulated low dielectric material or encapsulated air or a vacuum at the bottom of a notched gate. Due to the low dielectric constant at the site of interface between the gate and the source/drain, the capacitance loss at that site is significantly reduced.Type: GrantFiled: January 24, 2001Date of Patent: August 20, 2002Assignee: International Business Machines CorporationInventors: Atul C. Ajmera, Ka Hing (Samuel) Fung, Victor Ku, Dominic J. Schepis