Patents by Inventor Constantin Bulucea

Constantin Bulucea 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: 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: 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: 7642574
    Abstract: An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 220, 220U, 220V, 220W, 380, or 480) has a hypoabrupt vertical dopant profile below one (104 or 264) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108 or 268). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone. The body material preferably includes a more heavily doped pocket portion (120 or 280) situated along the other source/drain zone (102 or 262).
    Type: Grant
    Filed: October 31, 2007
    Date of Patent: January 5, 2010
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • 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
  • Patent number: 7595243
    Abstract: A semiconductor technology combines a normally off n-channel channel-junction insulated-gate field-effect transistor (“IGFET”) (104) and an n-channel surface-channel IGFET (100 or 160) to reduce low-frequency 1/f noise. The channel-junction IGFET is normally fabricated to be of materially greater gate dielectric thickness than the surface-channel IGFET so as to operate across a greater voltage range than the surface-channel IGFET. A p-channel surface-channel IGFET (102 or 162), which is typically fabricated to be of approximately the same gate-dielectric thickness as the n-channel surface-channel IGFET, is preferably combined with the two n-channel IGFETs to produce a complementary-IGFET structure. A further p-channel IGFET (106, 180, 184, or 192), which is typically fabricated to be of approximately the same gate dielectric thickness as the n-channel channel-junction IGFET, is also preferably included. The further p-channel IGFET can be a surface-channel or channel-junction device.
    Type: Grant
    Filed: July 28, 2006
    Date of Patent: September 29, 2009
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Philipp Lindorfer
  • Patent number: 7579642
    Abstract: A semiconductor junction varactor utilizes gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance.
    Type: Grant
    Filed: April 18, 2006
    Date of Patent: August 25, 2009
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • Publication number: 20080311717
    Abstract: An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 220, 220U, 220V, 220W, 380, or 480) is fabricated so as to have a hypoabrupt vertical dopant profile below one (104 or 264) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108 or 268). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone. The body material is preferably provided with a more heavily doped pocket portion (120 or 280) situated along the other source/drain zone (102 or 262).
    Type: Application
    Filed: October 31, 2007
    Publication date: December 18, 2008
    Inventor: Constantin Bulucea
  • Publication number: 20080308878
    Abstract: An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 220, 220U, 220V, 220W, 380, or 480) has a hypoabrupt vertical dopant profile below one (104 or 264) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108 or 268). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone. The body material preferably includes a more heavily doped pocket portion (120 or 280) situated along the other source/drain zone (102 or 262).
    Type: Application
    Filed: October 31, 2007
    Publication date: December 18, 2008
    Inventor: Constantin Bulucea
  • Patent number: 7419863
    Abstract: Complementary IGFETs (210W and 220W or 530 and 540) are fabricated so that the body dopant concentration in each IGFET decreases by at least 10 in moving from a subsurface location in the body material of that IGFET up to one of its source/drain zones. Semiconductor dopant, typically a fast-diffusing species such as aluminum, is introduced into starting semiconductor material to form a relatively uniformly doped region that serves as body material (108) for one of the IGFETs. A remaining part of the starting material serves as body material (268) for the other IGFET. Well dopant is introduced into the body material of each IGFET for establishing the requisite body dopant profile. Alternatively, a cavity is formed through an initial structure having body material (108) doped in the preceding way for one of the IGFETs. Semiconductor material is introduced into the cavity to form the body material (568) for the other IGFET.
    Type: Grant
    Filed: August 29, 2005
    Date of Patent: September 2, 2008
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • Patent number: 7235862
    Abstract: A semiconductor junction varactor utilizes gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance.
    Type: Grant
    Filed: July 10, 2001
    Date of Patent: June 26, 2007
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • Patent number: 7176530
    Abstract: A semiconductor technology combines a normally off n-channel channel-junction insulated-gate field-effect transistor (“IGFET”) (104) and an n-channel surface-channel IGFET (100 or 160) to reduce low-frequency 1/f noise. The channel-junction IGFET is normally of materially greater gate dielectric thickness than the surface-channel IGFET so as to operate across a greater voltage range than the surface-channel IGFET. Alternatively or additionally, the channel-junction IGFET may conduct current through a field-induced surface channel. A p-channel surface-channel IGFET (102 or 162), which is typically of approximately the same gate-dielectric thickness as the n-channel surface-channel IGFET, is preferably combined with the two n-channel IGFETs to produce a complementary-IGFET structure. A further p-channel IGFET (106, 180, 184, or 192), which is typically of approximately the same gate dielectric thickness as the n-channel channel-junction IGFET, is also preferably included.
    Type: Grant
    Filed: March 17, 2004
    Date of Patent: February 13, 2007
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Philipp Lindorfer
  • Patent number: 7145191
    Abstract: 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. Each 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.
    Type: Grant
    Filed: August 18, 2004
    Date of Patent: December 5, 2006
    Assignee: National Semiconductor Corporation
    Inventors: Chih Sieh Teng, Constantin Bulucea, Chin-Miin Shyu, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 7081663
    Abstract: A semiconductor junction varactor utilizes gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance. The varactor has a gate region (131 or 181) divided into multiple portions of differing zero-point threshold voltages for enabling the varactor capacitance to vary relatively gradually with a control voltage applied to the varactor.
    Type: Grant
    Filed: January 18, 2002
    Date of Patent: July 25, 2006
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • Patent number: 7078787
    Abstract: A semiconductor junction varactor is designed with gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance. The varactor has a gate region (131 or 181) divided into multiple portions of differing zero-point threshold voltages for enabling the varactor capacitance to vary relatively gradually with a control voltage applied to the varactor.
    Type: Grant
    Filed: October 31, 2003
    Date of Patent: July 18, 2006
    Assignee: National Semiconductor Corporation
    Inventor: Constantin Bulucea
  • Patent number: 7067879
    Abstract: The formation of vertical trench DMOS devices can be added to existing integrated BCD process flows in order to improve the efficiency of the BCD devices. The formation of this trench DMOS varies from existing approaches used with discrete trench DMOS devices, in that only two extra mask steps are added to the existing BCD process, instead of the 10 or so mask steps used in existing discrete trench DMOS processes. Further, the location of these additional heat cycles in the BCD process steps can be placed so as to have minimal impact on the other components created in the process. Utilizing an integrated trench device in a BCD process can offer at least a factor-of-two RDS(ON) area advantage over a planar counterpart.
    Type: Grant
    Filed: May 28, 2004
    Date of Patent: June 27, 2006
    Assignee: National Semiconductor Corporation
    Inventors: Terry Dyer, Jim McGinty, Andrew Strachan, Constantin Bulucea
  • Patent number: 6797576
    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 &mgr;m deep into the body material but not more than 0.1 &mgr;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: Grant
    Filed: December 20, 2002
    Date of Patent: September 28, 2004
    Assignee: National Semiconductor Corporation
    Inventors: Chih Sieh Teng, Constantin Bulucea, Chin-Miin Shyu, Fu-Cheng Wang, Prasad Chaparala
  • Patent number: 6627950
    Abstract: Power MOSFET apparatus, and method for its production, that suppresses voltage breakdown near the gate, using a polygon-shaped trench in which the gate is positioned, using a shaped deep body junction that partly lies below the trench bottom, and using special procedures for growth of gate oxide at various trench corners.
    Type: Grant
    Filed: May 5, 1997
    Date of Patent: September 30, 2003
    Assignee: Siliconix, Incorporated
    Inventors: Constantin Bulucea, Rebecca Rossen
  • Patent number: 6599804
    Abstract: Short-channel threshold voltage roll-off and punchthrough in an IGFET (40 or 42) having a channel zone (64 or 84) situated in body material (50) 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 &mgr;m deep into the body material but not more than 0.4 &mgr;m deep into the body material.
    Type: Grant
    Filed: September 4, 2001
    Date of Patent: July 29, 2003
    Assignee: National Semiconductor Corporation
    Inventors: Constantin Bulucea, Fu-Cheng Wang, Prasad Chaparala
  • Publication number: 20030137796
    Abstract: A semiconductor junction varactor utilizes gate enhancement for enabling the varactor to achieve a high ratio of maximum capacitance to minimum capacitance. The varactor has a gate region (131 or 181) divided into multiple portions of differing zero-point threshold voltages for enabling the varactor capacitance to vary relatively gradually with a control voltage applied to the varactor.
    Type: Application
    Filed: January 18, 2002
    Publication date: July 24, 2003
    Inventor: Constantin Bulucea