Apparatus and method for detecting an endpoint in a vapor phase etch

Abstract

Processes for the removal of a layer or region from a workpiece material by contact with a process gas in the manufacture of a microstructure are enhanced by the ability to accurately determine the endpoint of the removal step. A vapor phase etchant is used to remove a material that has been deposited on a substrate, with or without other deposited structure thereon. By creating an impedance at the exit of an etching chamber (or downstream thereof), as the vapor phase etchant passes from the etching chamber, a gaseous product of the etching reaction is monitored; and the endpoint of the removal process can be determined. The vapor phase etching process can be flow through, a combination of flow through and pulse, or recirculated back to the etching chamber

Description

BACKGROUND OF THE INVENTION [0001] This U.S. patent application is a divisional patent application of co-pending U.S. patent application Ser. No. 10 / 269,149 to Patel et al filed Oct. 10, 2002, which is a continuation in part of U.S. patent application Ser. No. 09 / 954,864 to Patel et al., filed Sep. 17, 2001. This application is related to U.S. patent application Ser. No. 09 / 427,841, to Patel et al., filed Oct. 26, 1999, and U.S. patent application Ser. No. 09 / 649,599 to Patel et al, filed Aug. 28, 2000, the subject matter of each being incorporated herein by reference.[0002] End point detection in plasma etching reactions is known in the art. However, end point detection by monitoring gases with a gas analyzer in a non-plasma system has not been available till now, particularly in a flow-through or recirculation etch system. Though other types of end point detection methods have been used in etch systems (optical monitoring, electrical monitoring, etc.), such methods can be difficul...

AI Technical Summary

Benefits of technology

[0005] The success of an etch step in the manufacture of microstructures is improved not only due to the selectivity of the etchant, but also due to the ability to accurately determine the endpoint of the etching process. Isotropic etching is of particular interest in processes where the purpose of the etch is to remove a sacrificial layer that is intervening between functional layers or between a functional layer and a substrate. Gas phase etchants, particularly in the absence of plasma, are desirable for isotropically removing a sacrificial layer.

Problems solved by technology

However, end point detection by monitoring gases with a gas analyzer in a non-plasma system has not been available till now, particularly in a flow-through or recirculation etch system.

Though other types of end point detection methods have been used in etch systems (optical monitoring, electrical monitoring, etc.), such methods can be difficult to set up and inaccurate.

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