초록 ▼

Apparatus and methods for end point detection during the plasma etching of integrated circuit wafers. Etching is conducted in a chamber subjected to the vacuum of a pump drawing at a constant volumetric gas flow rate. The etchant gases entering the chamber are regulated by a controller responsive to

Apparatus and methods for end point detection during the plasma etching of integrated circuit wafers. Etching is conducted in a chamber subjected to the vacuum of a pump drawing at a constant volumetric gas flow rate. The etchant gases entering the chamber are regulated by a controller responsive to a feedback loop sensing pressures within the chamber. Changes in the chamber\s chemical composition, which occur in time proximity to the end point of etching, affect the pressure and are detected as variations in the gas flow rates. Empirical results confirm the distinctiveness and repeatability which characterize the flow variations at the end point of etching.

대표청구항 ▼

A plasma etching system comprising: a plasma etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said

A plasma etching system comprising: a plasma etching chamber; means for sensing the molar content within said chamber; a source of first etchant gas; means for coupling said first gas into said chamber; first means, for regulating the flow rate of said first gas through said means for coupling said first gas; means for extracting gases from said chamber, second means, for regulating the flow rate of gases through said means for extracting; control means, responsive to said means for sensing the molar content, for actuating said first and second means for regulating, so that one means for regulating maintains a substantially constant flow rate while the other means for regulating responds to said means for sensing the molar content; and means for sensing changes, in the means for regulating which responds to said means for sensing the molar content, to detect the end point of etching. A method for determining the end point of plasma etching, comprising: coupling a plasma etching chamber to a source of vacuum and a source of etchant gas; regulating either the inlet gas flow rate or the gas flow rate to said source of vacuum, while holding the other substantially constant, to maintain a fixed molar content within said chamber; and sensing the time related change of said regulated gas flow during the progression of etching to detect transitions between substantially steady levels.