Patents by Inventor Prasad Chaparala

Prasad Chaparala 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).

  • Patent number: 8735980
    Abstract: A semiconductor structure, which serves as the core of a semiconductor fabrication platform, has a combination of empty-well regions and filled-well regions variously used by electronic elements, particularly insulated-gate field-effect transistors (“IGFETs”), to achieve desired electronic characteristics. A relatively small amount of semiconductor well dopant is near the top of an empty well. A considerable amount of semiconductor well dopant is near the top of a filled well. Some IGFETs (100, 102, 112, 114, 124, and 126) utilize empty wells (180, 182, 192, 194, 204, and 206) in achieving desired transistor characteristics. Other IGFETs (108, 110, 116, 118, 120, and 122) utilize filled wells (188, 190, 196, 198, 200, and 202) in achieving desired transistor characteristics.
    Type: Grant
    Filed: November 6, 2012
    Date of Patent: May 27, 2014
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Sandeep Bahl, William French, Jeng-Jiun Yang, Donald Archer, David C. Parker, Prasad Chaparala
  • Patent number: 8673720
    Abstract: An insulated-gate field-effect transistor (110, 114, or 122) is fabricated so that its gate dielectric layer (500, 566, or 700) contains nitrogen having a vertical concentration profile specially tailored to prevent boron in the overlying gate electrode (502, 568, or 702) from significantly penetrating through the gate dielectric layer into the underlying channel zone (484, 554, or 684) while simultaneously avoiding the movement of nitrogen from the gate dielectric layer into the underlying semiconductor body. Damage which could otherwise result from undesired boron in the channel zone and from undesired nitrogen in the semiconductor body is substantially avoided.
    Type: Grant
    Filed: March 27, 2009
    Date of Patent: March 18, 2014
    Assignee: National Semiconductor Corporation
    Inventors: Prasad Chaparala, D. Courtney Parker
  • Patent number: 8304835
    Abstract: A semiconductor structure, which serves as the core of a semiconductor fabrication platform, has a combination of empty-well regions and filled-well regions variously used by electronic elements, particularly insulated-gate field-effect transistors (“IGFETs”), to achieve desired electronic characteristics. A relatively small amount of semiconductor well dopant is near the top of an empty well. A considerable amount of semiconductor well dopant is near the top of a filled well. Some IGFETs (100, 102, 112, 114, 124, and 126) utilize empty wells (180, 182, 192, 194, 204, and 206) in achieving desired transistor characteristics. Other IGFETs (108, 110, 116, 118, 120, and 122) utilize filled wells (188, 190, 196, 198, 200, and 202) in achieving desired transistor characteristics.
    Type: Grant
    Filed: March 27, 2009
    Date of Patent: November 6, 2012
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Sandeep R. Bahl, William D. French, Jeng-Jiun Yang, Donald M. Archer, D. Courtney Parker, Prasad Chaparala
  • Publication number: 20120273880
    Abstract: An IGFET (40 or 42) has a channel zone (64 or 84) situated in body material (50). Short-channel threshold voltage roll-off and punchthrough are alleviated by arranging for the net dopant concentration in the channel zone to longitudinally reach a local surface minimum at a location between the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging for the net dopant concentration in the body material to reach a local subsurface maximum more than 0.1 ?m deep into the body material but not more than 0.1 ?m deep into the body material. The source/drain zones (140 and 142 or 160 and 162) of a p-channel IGFET (120 or 122) are provided with graded-junction characteristics to reduce junction capacitance, thereby increasing switching speed.
    Type: Application
    Filed: October 26, 2010
    Publication date: November 1, 2012
    Inventors: Chih Sieh Teng, Constantin Bulucea, Chin-Miin Shyu, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 8253208
    Abstract: A gate dielectric layer (500, 566, or 700) of an insulated-gate field-effect transistor (110, 114, or 122) contains nitrogen having a vertical concentration profile specially tailored to prevent boron in the overlying gate electrode (502, 568, or 702) from significantly penetrating through the gate dielectric layer into the underlying channel zone (484, 554, or 684) while simultaneously avoiding the movement of nitrogen from the gate dielectric layer into the underlying semiconductor body. Damage which could otherwise result from undesired boron in the channel zone and from undesired nitrogen in the semiconductor body is substantially avoided.
    Type: Grant
    Filed: March 31, 2011
    Date of Patent: August 28, 2012
    Assignee: National Semiconductor Corporation
    Inventors: Prasad Chaparala, D. Courtney Parker
  • Publication number: 20120181614
    Abstract: An IGFET (40 or 42) has a channel zone (64 or 84) situated in body material (50). Short-channel threshold voltage roll-off and punchthrough are alleviated by arranging for the net dopant concentration in the channel zone to longitudinally reach a local surface minimum at a location between the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging for the net dopant concentration in the body material to reach a local subsurface maximum more than 0.1 ?m deep into the body material but not more than 0.1 ?m deep into the body material. The source/drain zones (140 and 142 or 160 and 162) of a p-channel IGFET (120 or 122) are provided with graded-junction characteristics to reduce junction capacitance, thereby increasing switching speed.
    Type: Application
    Filed: December 1, 2011
    Publication date: July 19, 2012
    Inventors: Chih Sieh Teng, Constantin Bulucea, Chin-Miin Shyu, Fu-Cheng Wang, Prasad Chaparala
  • Publication number: 20120181620
    Abstract: An IGFET (40 or 42) has a channel zone (64 or 84) situated in body material (50). Short-channel threshold voltage roll-off and punchthrough are alleviated by arranging for the net dopant concentration in the channel zone to longitudinally reach a local surface minimum at a location between the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging for the net dopant concentration in the body material to reach a local subsurface maximum more than 0.1 ?m deep into the body material but not more than 0.1 ?m deep into the body material. The source/drain zones (140 and 142 or 160 and 162) of a p-channel IGFET (120 or 122) are provided with graded-junction characteristics to reduce junction capacitance, thereby increasing switching speed.
    Type: Application
    Filed: July 9, 2010
    Publication date: July 19, 2012
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala, Chih Sieh Teng, Chin-Miin Shyu
  • Patent number: 8129262
    Abstract: Fabrication of an insulated-gate field-effect transistor (110) entails separately introducing three body-material dopants, typically through an opening in a mask, into body material (50) of a semiconductor body so as to reach respective maximum dopant concentrations at three different vertical locations in the body material. A gate electrode (74) is subsequently defined after which a pair of source/drain zones (60 and 62), each having a main portion (60M or 80M) and a more lightly doped lateral extension (60E or 62E), are formed in the semiconductor body. An anneal is performed during or subsequent to introduction of semiconductor dopant that defines the source/drain zones. The body material is typically provided with at least one more heavily doped halo pocket portion (100 and 102) along the source/drain zones. The vertical dopant profile resulting from the body-material dopants alleviates punchthrough and reduces current leakage.
    Type: Grant
    Filed: October 27, 2009
    Date of Patent: March 6, 2012
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 7879669
    Abstract: At least one source/drain zone (140, 142, 160, or 162) of an enhancement-mode insulated-gate field-effect transistor (120 or 122) is provided with graded junction characteristics to reduce junction capacitance, thereby increasing switching speed. Each graded junction source/drain zone contains a main portion (140M, 142M, 160M, or 162M) and a more lightly doped lower portion (140L, 142L, 160L, or 162L) underlying, and vertically continuous with, the main portion. The magnitudes of the threshold voltages of a group of such transistors fabricated under the same post-layout fabrication process conditions so as to be of different channel lengths reach a maximum absolute value VTAM when the channel length is at a value LC, are at least 0.03 volt less than VTAM when the channel length is approximately 0.3 ?m greater than LC, and materially decrease with increasing channel length when the channel length is approximately 1.0 ?m greater than LC.
    Type: Grant
    Filed: September 25, 2006
    Date of Patent: February 1, 2011
    Assignee: National Semiconductor Corporation
    Inventors: Chih Sieh Teng, Constantin Bulucea, Chin-Miin Shyu, Fu-Cheng Wang, Prasad Chaparala
  • Publication number: 20100244148
    Abstract: A gate dielectric layer (500, 566, or 700) of an insulated-gate field-effect transistor (110, 114, or 122) contains nitrogen having a vertical concentration profile specially tailored to prevent boron in the overlying gate electrode (502, 568, or 702) from significantly penetrating through the gate dielectric layer into the underlying channel zone (484, 554, or 684) while simultaneously avoiding the movement of nitrogen from the gate dielectric layer into the underlying semiconductor body. Damage which could otherwise result from undesired boron in the channel zone and from undesired nitrogen in the semiconductor body is substantially avoided.
    Type: Application
    Filed: March 27, 2009
    Publication date: September 30, 2010
    Inventors: Prasad Chaparala, D. Courtney Parker
  • Publication number: 20100244128
    Abstract: A semiconductor structure, which serves as the core of a semiconductor fabrication platform, has a combination of empty-well regions and filled-well regions variously used by electronic elements, particularly insulated-gate field-effect transistors (“IGFETs”), to achieve desired electronic characteristics. A relatively small amount of semiconductor well dopant is near the top of an empty well. A considerable amount of semiconductor well dopant is near the top of a filled well. Some IGFETs (100, 102, 112, 114, 124, and 126) utilize empty wells (180, 182, 192, 194, 204, and 206) in achieving desired transistor characteristics. Other IGFETs (108, 110, 116, 118, 120, and 122) utilize filled wells (188, 190, 196, 198, 200, and 202) in achieving desired transistor characteristics.
    Type: Application
    Filed: March 27, 2009
    Publication date: September 30, 2010
    Inventors: Constantin Bulucea, Sandeep R. Bahl, William D. French, Jeng-Jiun Yang, Donald M. Archer, D. Courtney Parker, Prasad Chaparala
  • Patent number: 7785971
    Abstract: Fabrication of complementary first and second insulated-gate field-effect transistors (110 or 112 and 120 or 122) from a semiconductor body entails separately introducing (i) three body-material dopants into the body material (50) for the first transistor so as to reach respective maximum dopant concentrations at three different locations in the first transistor's body material and (ii) two body-material dopants into the body material (130) for the second transistor so as to reach respective maximum dopant concentrations at two different locations in the second transistor's body material. Gate electrodes (74 or 94 and 154 or 194) are subsequently defined after which source/drain zones (60, 62 or 80, 82 and 140, 142 or 160, 162) are formed in the semiconductor body. The vertical dopant profiles resulting from the body-material dopants alleviate punchthrough and reduce current leakage.
    Type: Grant
    Filed: February 6, 2007
    Date of Patent: August 31, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 7718448
    Abstract: A number of modified lateral DMOS (LDMOS) transistor arrays are formed and tested to determine if a measured value, such as a series on-resistance, substrate current, breakdown voltage, and reliability, satisfies process alignment requirements. The modified LDMOS transistor arrays are similar to standard LDMOS transistor arrays such that the results of the modified LDMOS transistor arrays can be used to predict the results of the standard LDMOS transistor arrays.
    Type: Grant
    Filed: May 27, 2005
    Date of Patent: May 18, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Douglas Brisbin, Prasad Chaparala
  • Patent number: 7701005
    Abstract: Each of a pair of differently configured like-polarity insulated-gate field-effect transistors (40 or 42 and 240 or 242) in a semiconductor structure has a channel zone of semiconductor body material, a gate dielectric layer overlying the channel zone, and a gate electrode overlying the gate dielectric layer. For each transistor, the net dopant concentration of the body material reaches multiple local subsurface maxima below a channel surface depletion region and below largely all gate-electrode material overlying the channel zone. The transistors have source/drain zones (60 or 80) of opposite conductivity type to, and halo pocket portions of the same conductivity type as, the body material. One pocket portion (100/102 or 104) extends along both source/drain zones of one of the transistors. Another pocket portion (244 or 246) extends largely along only one of the source/drain zones of the other transistor so that it is asymmetrical.
    Type: Grant
    Filed: October 15, 2007
    Date of Patent: April 20, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 7700980
    Abstract: Each of a pair of like-polarity IGFETs (40 or 42 and 240 or 242) has a channel zone (64 or 84) situated in body material (50). Short-channel effects are alleviated by arranging for the net dopant concentration in the channel zone to longitudinally reach a local surface minimum at a location between the IGFET's source/drain zones (60 and 62 or 80 and 82) and by arranging for the net dopant concentration in the body material to reach a local subsurface maximum more than 0.1 ?m deep into the body material but not more than 0.4 ?m deep into the body material. A pocket portion (100/102 or 104) extends along both source drain zones of one of the IGFETs. A pocket portion (244 or 246) extends largely along only one of the source/drain zones of the other IGFET so that it is an asymmetrical device.
    Type: Grant
    Filed: October 17, 2007
    Date of Patent: April 20, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 7645657
    Abstract: A MOS transistor is formed with a dual-layer silicon oxynitride (SiON) etch stop film that protects the transistor from plasma induced damage (PID) and hot carrier degradation, thereby improving the reliability of the transistors. The first SiON layer is formed with SiH4 at a first flow rate, and the second SiON layer is formed with SiH4 at a second higher flow rate.
    Type: Grant
    Filed: December 10, 2007
    Date of Patent: January 12, 2010
    Assignee: National Semiconductor Corporation
    Inventors: Douglas Brisbin, Prasad Chaparala, Denis Finbarr O'Connell, Heather McCulloh, Sergei Drizlikh
  • Patent number: 7595244
    Abstract: Fabrication of two differently configured like-polarity insulated-gate field-effect transistors (40 or 42 and 240 or 242) entails introducing multiple body-material semiconductor dopants of the same conductivity type into a semiconductor body. Gate electrodes (74 or 94) are defined such that each body-material dopant reaches a maximum concentration below the channel surface depletion regions, below all gate-electrode material overlying the channel zones (64 or 84), and at a different depth than each other body-material dopant. The transistors are provided with source/drain zones (60 or 80) of opposite conductivity type to, and with halo pocket portions of the same conductivity type as, the body-material dopants. One pocket portion (100/102 or 104) extends along both source/drain zones of one of the transistors. Another pocket portion (244 or 246) extends largely along only one of the source/drain zones of the other transistor so that it is asymmetrical.
    Type: Grant
    Filed: October 16, 2007
    Date of Patent: September 29, 2009
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Publication number: 20090146192
    Abstract: A MOS transistor is formed with a dual-layer silicon oxynitride (SiON) etch stop film that protects the transistor from plasma induced damage (PID) and hot carrier degradation, thereby improving the reliability of the transistors. The first SiON layer is formed with SiH4 at a first flow rate, and the second SiON layer is formed with SiH4 at a second higher flow rate.
    Type: Application
    Filed: December 10, 2007
    Publication date: June 11, 2009
    Inventors: Douglas Brisbin, Prasad Chaparala, Denis Finbarr O'Connell, Heather McCulloh, Sergei Drizlikh
  • Patent number: 7390682
    Abstract: A test methodology is provided for testing metal-insulator-metal (MIM) capacitor structures under high temperatures at the wafer level. A resistor is formed on a region of dielectric isolation material formed in a semiconductor substrate. The MIM capacitor is formed over the resistor and separated therefrom by dielectric material. A metal thermometer, formed from the same material as the plates of the MIM capacitor, is placed above the resistor and in close proximity to the capacitor. High current is forced through the resistor, causing both the metal thermometer and the MIM capacitor to heat up along with the resistor. The change in resistance of the metal thermometer is monitored. Using the known temperature coefficient of resistance (TCR) for the metal used to form both the capacitor and the thermometer, changes in the measured resistance of the metal thermometer are converted to temperature.
    Type: Grant
    Filed: November 3, 2006
    Date of Patent: June 24, 2008
    Assignee: National Semiconductor Corporation
    Inventors: Prasad Chaparala, Barry O'Connell, Jonggook Kim
  • Publication number: 20070051951
    Abstract: A test methodology is provided for testing metal-insulator-metal (MIM) capacitor structures under high temperatures at the wafer level. A resistor is formed on a region of dielectric isolation material formed in a semiconductor substrate. The MIM capacitor is formed over the resistor and separated therefrom by dielectric material. A metal thermometer, formed from the same material as the plates of the MIM capacitor, is placed above the resistor and in close proximity to the capacitor. High current is forced through the resistor, causing both the metal thermometer and the MIM capacitor to heat up along with the resistor. The change in resistance of the metal thermometer is monitored. Using the known temperature coeffecient of resistance (TCR) for the metal used to form both the capacitor and the thermometer, changes in the measured resistance of the metal thermometer are converted to temperature.
    Type: Application
    Filed: November 3, 2006
    Publication date: March 8, 2007
    Inventors: Prasad Chaparala, Barry O'Connell, Jonggook Kim