Materials and methods for plasma etching of oxides and nitrides of silicon
AssigneeApplied Materials, Inc.
InventorsDavid N. Wang, Frank D. Egitto, Dan Maydan
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Abstract
A method for etching a layer of inorganic insulating material formed on a semiconductor wafer and containing silicon as the principal metallic element. The method involves disposing a wafer on one of a pair of electrode structures in a closed chamber. A reactive gas mixture comprising principally a fluorocarbon gas doped with a preselected quantity of carbon dioxide is supplied to the chamber. Radio frequency electrical energy is supplied to one of the electrode structures to create a plasma of the reactive gas mixture for chemically attacking the insulating material.
Claims12
In a method for etching a layer of inorganic insulating material formed on a semiconductor wafer and containing silicon as the principal metallic element, the steps of:
- disposing said wafer on one of a pair of electrode structures in a closed chamber;
- communicating into said chamber a reactive gas mixture comprising principally a fluorocarbon gas doped with a preselected quantity of carbon dioxide;
- and
- supplying radio frequency electrical energy to one of said electrode structures to create a plasma of said reactive gas mixture for chemically attacking said insulating material.
In a method for forming a pattern of apertures with substantially straight side walls in a layer of inorganic insulating material formed on a semiconductor wafer and comprising silicon as the principal metallic element therein, the steps of:
- forming a layer of photoresist on said insulating material layer;
- exposing preselected regions of said photoresist layer to preselected electromagnetic radiation to write a mask pattern therein;
- developing said written photoresist layer with a preselected developing solution;
- disposing said sustrate on the cathode structure of a reactive ion etching chamber without postbaking said developed photoresist layer;
- and
- simultaneously supplying radio frequency electrical energy to said cathode structure at a power level which creates a power density in the range of about 0.18-0.26 watts/cm.sup.2 and supplying to said chamber a reactive gas mixture comprising principally CHF.sub.3 doped with carbon dioxide in the range of 5-15 percent by volume while maintaining said chamber at a pressure in the range of about 40-80 millitorr, said reactive gas mixture being supplied at a total gas flow rate which produces a residence time of activated species in the range of 6-30 seconds.
In a method for forming a pattern of apertures with substantially sloping side walls in a layer of inorganic insulating material formed on a semiconductor wafer and comprising silicon as the principal metallic element therein, the steps of:
- forming a layer of photoresist on said insulating material layer;
- exposing preselected regions of said photoresist layer to preselected electromagnetic radiation to write a mask pattern therein;
- developing said written photoresist layer with a preselected developing solution to produce apertures therein corresponding to said written mask pattern;
- disposing said substrate on the cathode structure of a reactive ion etching chamber without postbaking said developed photoresist layer;
- and
- simultaneously applying radio frequency electrical energy to said cathode structure at a power level which creates a power density in the range of about 0.18-0.26 watts/cm.sup.2 and supplying to said chamber a reactive gas mixture comprising principally a fluorocarbon gas heavily doped with one or more oxygen plasma forming gas constituents, the concentration of said oxygen plasma forming gas being selected at a value in the range of 20-50 percent to produce a predetermined etch rate ratio of said insulating material to said photoresist thereby to control the angle of said sloping side wall formed in said insulating material.
A method for operating a reactive ion etching system for high resolution, highly uniform replication of a pattern of apertures in a layer of organic photoresist into an underlying layer of inorganic insulating material on a semiconductor wafer and containing silicon as the principal metallic element, the method producing anisotropic etching with no polymer formation on the wafer, with low polymer formation on surfaces of the chamber of the system, and with substantial etch rate selectivity for the insulating material over the photoresist material, the method comprising:
- disposing said wafer on the cathode structure within the chamber of said reactive ion etching system;
- supplying to said chamber a reactive gas mixture comprising principally CHF.sub.2 doped with carbon dioxide in the range of about 5-15 percent by volume;
- and supplying radio frequency energy to said cathode structure to create a plasma of said reactive gas mixture.
A reactive gas mixture adapted to be used in a reactive ion system for etching silicon nitride or silicon oxide layers at relatively high etch rates with high etch rate selectivity for both an underlying layer of silicon and an overlying layer of photoresist, said mixture comprising principally CHF.sub.3 doped with carbon dioxide in the range of about 5-15 percent by volume.
Dependencies are inferred from the claim text.