Patents by Inventor Gangadhara S. Mathad

Gangadhara S. Mathad 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: 4671849
    Abstract: A method for precisely controlling the profile of an opening etched in a layer of material, for example, an insulating layer. In one embodiment, wherein a silicon dioxide layer is reactive ion etched through a photoresist mask, the concentration of a reactive species in an etchant gas is changed during the etching process to change the slope of the opening, the upper sidewall portion of the opening having a shallow slope and the lower sidewall portion of the opening having a steep slope. The final slope of the opening formed by this method is independent of the initial slopes of the images developed in the photoresist mask.
    Type: Grant
    Filed: May 6, 1985
    Date of Patent: June 9, 1987
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Gangadhara S. Mathad
  • Patent number: 4617730
    Abstract: Disclosed is a method of fabricating a multichip interposer comprising an insulating support with thin film fine line metallization on one side thereof. A layer of masking material is adhered to in other side and selective areas of the masking material are removed in a desired pattern to expose areas of the support. The exposed areas of the support are then etched until the metallization is reached to form via holes which are subsequently filled with interconnecting metallurgy. Contact pads are then formed around each filled via hole.
    Type: Grant
    Filed: August 13, 1984
    Date of Patent: October 21, 1986
    Assignee: International Business Machines Corporation
    Inventors: Pieter Geldermans, Gangadhara S. Mathad
  • Patent number: 4602981
    Abstract: Plasma potential monitoring during a plasma etching process is accomplished by measuring the RF voltage at an electrode of, for example, a high pressure, high plasma density, symmetric single wafer reactor. The plasma potential is indicative of the plasma density, which has a high sensitivity to secondary electron emission from a wafer surface and yields both process etching endpoint and diagnostic information for a wide variety of processes and process conditions.
    Type: Grant
    Filed: May 6, 1985
    Date of Patent: July 29, 1986
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Gangadhara S. Mathad
  • Patent number: 4534816
    Abstract: A high pressure, high etch rate single wafer plasma reactor having a fluid cooled upper electrode including a plurality of small diameter holes or passages therethrough to provide uniform reactive gas distribution over the surface of a wafer to be etched. A fluid cooled lower electrode is spaced from the upper electrode to provide an aspect ratio (wafer diameter: spacing) greater than about 25, and includes an insulating ring at its upper surface. The insulating ring protrudes above the exposed surface of the lower electrode to control the electrode spacing and to provide a plasma confinement region whereby substantially all of the RF power is dissipated by the wafer. A plurality of spaced apart, radially extending passages through the insulating ring provide a means of uniformly exhausting the reactive gas from the plasma confinement region.
    Type: Grant
    Filed: June 22, 1984
    Date of Patent: August 13, 1985
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Charles J. Hendricks, Gangadhara S. Mathad, Stanley J. Poloncic
  • Patent number: 4511430
    Abstract: A method of controlling the etch rate ratio of SiO.sub.2 /photoresist (PR) in a quartz planarization etch back process involves etching with a gaseous mixture containing CF.sub.4 and either CHF.sub.3 or C.sub.x F.sub.y with x>1 or O.sub.2. The preferred SiO.sub.2 /PR ratio of 1.2.+-.0.1 is obtained by either adding CHF.sub.3 to decrease the etch rate of the PR or by adding O.sub.2 to increase the etch rate of the PR.
    Type: Grant
    Filed: January 30, 1984
    Date of Patent: April 16, 1985
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Gangadhara S. Mathad
  • Patent number: 4490211
    Abstract: Disclosed is a method of etching a metallized substrate by excimer laser radiation. The substrate is exposed to a selected gas, e.g., a halogen gas, which spontaneously reacts with the metal forming a solid reaction product layer on the metal by a partial consumption of the metal. A beam of radiation from an excimer laser, e.g. XeF laser operating at a wavelength of 351 nm or XeCl laser at 308 nm or KrF laser at 248 nm or KrCl laser at 222 nm or ArF laser at 193 nm or F.sub.2 laser at 157 nm, is applied to the reaction product in a desired pattern to vaporize the reaction product and thereby selectively etch the metal with a high resolution.
    Type: Grant
    Filed: January 24, 1984
    Date of Patent: December 25, 1984
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, John R. Lankard, Gangadhara S. Mathad
  • Patent number: 4490210
    Abstract: Disclosed is a method of etching a metallized substrate by laser radiation. The substrate is exposed to a selected gas which spontaneously reacts with the metal forming a solid reaction product with the metal by a partial consumption of the metal. A beam of radiation of a wavelength suitable for absorption by the reaction product and/or by the metal thereunder is applied in a desired pattern to vaporize the reaction product and thereby selectively etch the metal.
    Type: Grant
    Filed: January 24, 1984
    Date of Patent: December 25, 1984
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Tung J. Chuang, Gangadhara S. Mathad
  • Patent number: 4478677
    Abstract: Disclosed is an apparatus and method for etching a glass substrate by laser induced dry etching. The apparatus features a housing including a vacuum chamber for receiving the substrate; a vacuum pump coupled to the chamber for evacuating the chamber; a gas source coupled to the chamber for supplying a halogen base gas which is capable of wetting the substrate surface and forming a glass etching specie when activated; a laser source for transmitting a light beam of predetermined wavelength and intensity through the gas; and a mask optically coupled to the laser source for patterning the light beam and also coupled to the chamber so that the light patterned by the mask may fall upon the substrate causing excitation thereof and activation of an etch specie for etching the substrate in conformity with the patterned light.
    Type: Grant
    Filed: December 22, 1983
    Date of Patent: October 23, 1984
    Assignee: International Business Machines Corporation
    Inventors: Lee Chen, Tung J. Chuang, Gangadhara S. Mathad