Etchant mixing system for edge bevel removal of copper from silicon wafers
AssigneeNovellus Systems, Inc.
InventorsSteven T. Mayer, John B. Alexy, Jinbin Feng
Life of this patent
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Abstract
A chemical etching system provides a mixture of sulfuric acid and hydrogen peroxide and serves as the etchant for removing residual copper from an edge bevel region of a semiconductor wafer. The etching system includes a dilution module where concentrated sulfuric acid and concentrated hydrogen peroxide are diluted to the appropriate concentrations and then stored. To reduce the likelihood that oxygen bubbles (from hydrogen peroxide decomposition) will appear in the etchant solution, stored sulfuric acid and hydrogen peroxide are mixed immediately prior to use. In this manner, the dissolved oxygen concentration in the hydrogen peroxide decreases well below the saturation level.
Claims24
A chemical dilution module for providing liquid etchant to an etching system that etches unwanted copper from a semiconductor wafer, the chemical dilution module comprising:
- an acid dilution tank for mixing concentrated acid and water to a specified concentration;
- a hydrogen peroxide dilution tank for diluting concentrated hydrogen peroxide to a specified concentration;
- and
- an in-line mixing area for combining hydrogen peroxide from the hydrogen peroxide dilution tank with diluted acid, whereby mixing occurs principally when hydrogen peroxide and acid are delivered to the etching system.
A method of providing liquid etchant to an etching system that etches unwanted copper from a semiconductor wafer, the method comprising:
- diluting concentrated acid in an acid dilution tank;
- diluting concentrated hydrogen peroxide in a hydrogen peroxide dilution tank;
- and
- in a single line to the etching system, mixing dilute acid and dilute hydrogen peroxide from the dilution tanks, whereby mixing occurs principally when hydrogen peroxide and acid are delivered to the etching system.
Dependencies are inferred from the claim text.