Etch end point detector using gas flow changes
AssigneeInternational Business Machines Corporation
InventorsBrian H. Desilets, Thomas A. Gunther
Life of this patent
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Abstract
As etching progresses from one layer of material to another in reactive ion etching systems, the partial pressures of the reaction chamber gas components change. In constant pressure reactive ion etching systems, changes in chamber pressure are corrected by changes in the etchant species flow rate into the reaction chamber. By monitoring flow rate, information is obtained which may be used to identify the points where partial pressures change, and latter may, in turn, be used to derive etching points in the material being etched.
Claims11
A method of detecting etch end point in reactive ion etching, comprising the steps of,
- monitoring the rate of flow of etchant species into a reactive ion etching reaction chamber wherein said rate of flow of etchant species into said chamber is a function of gas species pressure within said chamber;
- and
- detecting etch end point by monitoring changes in the rate of flow of etchant species into said chamber with said changes in the rate of flow of etchant species into said chamber being indicative of changes in the partial pressure of constituent species within said chamber caused by changes in the material being etched.
A method of detecting etch end point in a reactive ion etching chamber, comprising the steps of:
- monitoring chamber pressure to sense changes in pressure caused by changes in gas species within said chamber with said changes in gas species being caused by changes in the material being etched in said chamber;
- controlling the rate of etchant species gas flow into said chamber in accordance with sensed changes in pressure so as to maintain a constant pressure within said chamber;
- monitoring the rate of etchant species gas flow into said chamber;
- and
- detecting etch end point by detecting changes in the rate of flow of etchant species into said chamber with said changes in the rate of flow of etchant species being indicative of changes in the material being etched.
In a batch processing reactive ion etching system wherein pressure within the system reaction chamber is sensed to control through flow regulator means the flow of etchant species into said chamber to maintain constant pressure therein, the improvement residing in an arrangement for detecting etch end point, comprising;
- means to sense the rate of flow of etchant species through said flow regulator means into said chamber and provide an electrical signal indicative of said rate of flow;
- and
- means to detect etch end point including means to monitor said electrical signal indicative of said rate of flow of etchant species into said chamber to detect changes in the rate of flow of etchant species wherein said changes in the rate of flow of etchant species are indicative of changes in the material being etched in said reaction chamber.
Dependencies are inferred from the claim text.