Patents by Inventor Rajan Nagabushnam

Rajan Nagabushnam 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: 6284633
    Abstract: A tPEN layer (108) having a tensile stress is formed over a conductive gate stack (104-106) provided on a semiconductor substrate. Following the formation of the conductive gate stack (104-106), an anneal is performed. The conductive gate stack includes a metal layer to prevent outgassing and poly depletion during the anneal. Next, a photoresist layer (110) is formed and patterned to form a gate (122, 124).
    Type: Grant
    Filed: November 24, 1997
    Date of Patent: September 4, 2001
    Assignee: Motorola Inc.
    Inventors: Rajan Nagabushnam, Stanley M. Filipiak, Bruce Boeck
  • Patent number: 6171959
    Abstract: A process for forming a silicided MOS transistor (100) begins by providing source and drain regions (104) and (106) and a gate electrode (110). Silicon nitride spacers (116) are formed adjacent the gate electrode (110). A cobalt layer (118) and an overlying titanium layer (120) are then deposited in contact with the regions (104), (106), and (110). A rapid thermal process (130) is then used to react the titanium, cobalt, and silicon together to form silicide regions (124), (126), and (128), and intermetallic compound layers (132) and (134). The intermetallic compound layers (132) and (134) are then etched using two sequentially-performed wet etch steps (136) and (138). The resulting structure (100) has a nitride spacer (116) and field oxide regions (107) which are free from cobalt residual contamination (38).
    Type: Grant
    Filed: January 20, 1998
    Date of Patent: January 9, 2001
    Assignee: Motorola, Inc.
    Inventor: Rajan Nagabushnam
  • Patent number: 6146250
    Abstract: Vibrating and oscillating rates can be dynamically changed during polishing to achieve an optimal polishing process. A semiconductor device substrate (34) has a first layer with a first film (12) and a second film (10) that overlies the first film (12), where the first film (12) is harder and underlies the second film (10). In one embodiment, the substrate (34) is placed over a first region (66) of a polishing pad (60). The second film (10) is polished at a first vibrating and oscillating rates over the first region (66). An endpoint signal is received when the first film (12) is reached. The substrate (34) is moved to a second region (62) of the polishing pad (60) that is closer to the edge of the pad and has a higher feature density compared to the first region (66). Polishing is performed at a second vibrating and oscillating rates that are different from the first vibrating and oscillating rates to remove the first film (10).
    Type: Grant
    Filed: July 15, 1999
    Date of Patent: November 14, 2000
    Assignee: Motorola, Inc.
    Inventors: Rajan Nagabushnam, Subramoney V. Iyer
  • Patent number: 6012970
    Abstract: Vibrating and oscillating rates can be dynamically changed during polishing to achieve an optimal polishing process. A semiconductor device substrate (34) has a first layer with a first film (12) and a second film (10) that overlies the first film (12), where the first film (12) is harder and underlies the second film (10). In one embodiment, the substrate (34) is placed over a first region (66) of a polishing pad (60). The second film (10) is polished at a first vibrating and oscillating rates over the first region (66). An endpoint signal is received when the first film (12) is reached. The substrate (34) is moved to a second region (62) of the polishing pad (60) that is closer to the edge of the pad and has a higher feature density compared to the first region (66). Polishing is performed at a second vibrating and oscillating rates that are different from the first vibrating and oscillating rates to remove the first film (10).
    Type: Grant
    Filed: January 15, 1997
    Date of Patent: January 11, 2000
    Assignee: Motorola, Inc.
    Inventors: Rajan Nagabushnam, Subramoney V. Iyer
  • Patent number: 6001726
    Abstract: A method for forming a contact structure (10) which enables the use of ultra-shallow source/drain junctions begins by forming source and drain regions (14) and gate electrode (16). The source and drain regions (14) and the gate electrode (16) are silicided to form silicide regions (20). A conductive tungsten nitride etch stop layer (22) is formed overlying the silicide regions (20). Contact plug regions (28) are then formed to contact to the etch stop layer (22) and silicided regions (20). At this point, all of the silicide regions (20) are electrically short circuited. To remove this electric short circuit, an isotropic etch process comprising hydrogen peroxide, ammonium hydroxide, and water is used to remove portions of the tungsten nitride regions which are between the individual contact portions (28) in a self-aligned manner.
    Type: Grant
    Filed: March 24, 1997
    Date of Patent: December 14, 1999
    Assignee: Motorola, Inc.
    Inventors: Rajan Nagabushnam, Rajeev Bajaj, Ram Venkataraman, Shyam Mattay, Subramoney V. Iyer
  • Patent number: 5888588
    Abstract: A semiconductor device (10) includes a gate electrode (61) having a silicon/tungsten nitride/tungsten silicon nitride/tungsten silicide composition. The tungsten nitride film (21) and tungsten suicide film (23) are formed using chemical vapor deposition (CVD). The tungsten nitride film is formed using a tungsten halide and N.sub.2 R.sup.1 R.sup.2, where each of R.sup.1 and R.sup.2 is hydrogen, an alkyl group, an alkenyl group, or an alkynyl group. The tungsten nitride film (21) is an etch stop when patterning the tungsten silicide film (23). The CVD tungsten nitride film (21) helps to improve gate dielectric integrity and reduces interface traps when compared to a sputtered tungsten nitride film (21). Also, N.sub.2 R.sup.1 R.sup.2 can be used to remove halogens that are adsorbed onto walls of a reaction chamber than is cleaned between depositions of substrates.
    Type: Grant
    Filed: March 31, 1997
    Date of Patent: March 30, 1999
    Assignee: Motorola, Inc.
    Inventors: Rajan Nagabushnam, Olubunmi Adetutu, Yeong-Jyh Tom Lii