Patents by Inventor Seshadri Ramaswami

Seshadri Ramaswami 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: 5456756
    Abstract: A holding apparatus, a metal deposition system and a wafer processing method which preserve topographical marks, including those used as alignment targets, on a semiconductor wafer by preventing metal from depositing on such marks during metal deposition. The invention eliminates the need to use window mask and etch techniques to provide replication of topographical marks on a newly formed metal layer when a CMP planarization technique is used prior to metal deposition. As a result, cost, cycle time and yield loss due to the additional window mask and etch steps can be eliminated. The holding apparatus includes a wafer retainer for retaining a wafer which has at least one topographical mark and a clamp ring with at least one tab. The wafer is pressed against the clamp ring by the retainer for securing the wafer in the retainer.
    Type: Grant
    Filed: September 2, 1994
    Date of Patent: October 10, 1995
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Seshadri Ramaswami, Darin A. Chan
  • Patent number: 5453402
    Abstract: Metal pillars (18) having diameters of less than about 1.0 .mu.m are grown in vias (16) in dielectric layers (14) between metal layers (12, 22) by a process comprising: (a) forming a first metal layer (12) at a first temperature and patterning the metal layer; (b) forming the dielectric layer to encapsulate the first patterned metal layer, the dielectric layer having a compressive stress of at least about 100 MegaPascal and being formed at a second temperature; (c) opening vias in the dielectric layer to exposed underlying portions of the patterned metal layer, the vias being less than about 1.0 .mu.m in diameter; (d) heating the semiconductor wafer at a temperature that is greater than either the first or second temperatures to induce growth of metal in the vias from the metal layer; and (e) forming the second metal layer (22) over the dielectric layer to make contact with the metal pillars.
    Type: Grant
    Filed: December 15, 1992
    Date of Patent: September 26, 1995
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Robin W. Cheung, Seshadri Ramaswami, David F. Kyser
  • Patent number: 5451545
    Abstract: A local interconnect silicide structure (30) for connecting silicon regions (16) to silicon regions (20) separated by oxide regions (24) comprises a first portion of titanium silicide/titanium nitride/titanium silicide contacting the silicon regions and a second portion of titanium/titanium nitride/titanium silicide contacting the oxide regions. The silicide structure is also useful for connecting source/drain regions (14) and polysilicon interconnects (28). Two separate heating steps are employed, separated by an etch step to form the interconnects (34, 36). The first heating step forms (a) titanium silicides with single or polycrystalline silicon, using a first titanium layer (30a) at the bottom of the silicide structure and (b) titanium silicides with amorphous silicon (30d), using a second titanium layer (30c) on top of the titanium nitride layer (30b) on which the amorphous silicon is deposited and then patterned.
    Type: Grant
    Filed: September 21, 1994
    Date of Patent: September 19, 1995
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Seshadri Ramaswami, Robin W. Cheung
  • Patent number: 5365111
    Abstract: A local interconnect silicide structure (30) for connecting silicon regions (16) to silicon regions (20) separated by oxide regions (24) comprises a first portion of titanium silicide/titanium nitride/titanium silicide contacting the silicon regions and a second portion of titanium/titanium nitride/titanium silicide contacting the oxide regions. The silicide structure is also useful for connecting source/drain regions (14) and polysilicon interconnects (28). Two separate heating steps are employed, separated by an etch step to form the interconnects (34, 36). The first heating step forms (a) titanium silicides with single or polycrystalline silicon, using a first titanium layer (30a) at the bottom of the silicide structure and (b) titanium silicides with amorphous silicon (30d), using a second titanium layer (30c) on top of the titanium nitride layer (30b) on which the amorphous silicon is deposited and then patterned.
    Type: Grant
    Filed: December 23, 1992
    Date of Patent: November 15, 1994
    Assignee: Advanced Micro Devices, Inc.
    Inventors: Seshadri Ramaswami, Robin W. Cheung