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Method for Etching Thin Film Chromium with a Gas Mixture of Methylene Chloride and Oxygen

IP.com Disclosure Number: IPCOM000112426D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

O'Grady, DS: AUTHOR

Abstract

Described is a method for etching thin film chromium semiconductor manufacturing masks. The method uses a gas mixture of methylene chloride (CH2Cl2) and oxygen (O2) in a plasma chamber. Plasma-etching process conditions are given which yield masks that are free from chromium undercutting and the effects of pattern-sensitive loading.

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Method for Etching Thin Film Chromium with a Gas Mixture of Methylene
Chloride and Oxygen

      Described is a method for etching thin film chromium
semiconductor manufacturing masks.  The method uses a gas mixture of
methylene chloride (CH2Cl2) and oxygen (O2) in a plasma chamber.
Plasma-etching process conditions are given which yield masks that
are free from chromium undercutting and the effects of
pattern-sensitive loading.

      The plasma etching process for chromium includes many complex
reactions and side reactions.  Two important mechanisms which occur
when CH2Cl2 and O2 are used are the etching of the chromium and the
deposition of a polymer film.  Deposition of a polymer film on the
side walls of the chromium images prevents: (1) undercutting of the
chromium image, and (2) variations in undercutting caused by
pattern-sensitive loading attributable to variations in photoresist
pattern density.  The process is compatible with conventional
photoresist materials.

      The ideal balanced reaction for chromium etching is:

     Cr + CH2Cl2(g) + 5/2 O2(g) ---> CrO2Cl2(g) + CO2 + H2O(g)

Process conditions which result in the desired etch include:

     Gas Flows:
        CH2Cl2      =  15 cc/min.
        O2          =  15 cc/min.
     Power Density: =  2 W/cm2
     Pressure :     =  90 mT