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Selective Removal of Materials in the Presence of Silicon and Silicon Dioxide

IP.com Disclosure Number: IPCOM000120930D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 1 page(s) / 35K

Publishing Venue

IBM

Related People

Hill, C: AUTHOR [+4]

Abstract

By adding oxygen to the reactive ion etching (RIE) system environment and adjusting system parameters to create an oxidizing environment for silicon (Si) while using nitrogen trifluoride (NF3) as primary etch gas, materials, e.g., silicon nitride (Si3N4), are removed at a rate much higher than the rate at which either Si or SiO2 are removed. Since there is no carbon (C) in gases used in this RIE process, there are no polymer deposits and the system remains quite clean.

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Selective Removal of Materials in the Presence of Silicon and Silicon
Dioxide

      By adding oxygen to the reactive ion etching (RIE) system
environment and adjusting system parameters to create an oxidizing
environment for silicon (Si) while using nitrogen trifluoride (NF3)
as primary etch gas, materials, e.g., silicon nitride (Si3N4), are
removed at a rate much higher than the rate at which either Si or
SiO2 are removed.  Since there is no carbon (C) in gases used in this
RIE process, there are no polymer deposits and the system remains
quite clean.

      By admitting NF3 and some form of oxidizing gas, e.g., O2, O3,
etc., at an appropriate flow ratio and properly adjusting system
pressure, electrical power, and magnetic field, exposed Si and SiO2
are etched at a rate much lower than the rate of removal of exposed
material, e.g., Si3N4 . In one system, conditions shown below
produced etch rate ratios of Si3N4:SiO2 = 6.5:1 and Si3N4:Si = 3.7:1.
      System Pressure = 300 millitorr
      Power = 40 watts
      O2 Flow = 18 standard cubic centimeters per minute
      (sccm)
      NF3 Flow = 3 sccm
      Magnetic Field = None applied above ambient.

      Disclosed anonymously.