Patent ID: 9159599
Filing Date: 2015-10-13
Classification: H01J,H01L

Abstract:
1. Apparatus for chemically etching a workpiece using a process gas, the apparatus including: a process chamber in which the process gas is received, and having a pumping port comprising an orifice through which exhaust gases are extracted from the process chamber, the process chamber including a main chamber and a sub-chamber; a workpiece support located in the main chamber of the process chamber; wherein the sub-chamber is located upstream of the pumping port and downstream of the workpiece support with respect to the flow of gas through the apparatus, and the interior of the sub-chamber has a volume smaller than that of the main chamber of the process chamber, the sub-chamber has a sub-chamber wall including a first portion and a second portion, the first portion defining a main part of the sub-chamber and carrying the pumping port, and the second portion defining an extension or dead end leading out of the main part of the sub-chamber, the orifice has a diameter that is smaller than a diameter of the main part of the sub-chamber, each as taken in the same direction, the sub-chamber is devoid of flow controls that regulate the flow of gas from the main portion of the process chamber to the orifice of the pumping port, the sub-chamber also has a window in the second portion of the sub-chamber wall, and an excitation source adjacent the window, the window is generally opposite the orifice of the pumping port, and the excitation source is configured to produce a plasma in the extension or dead end, thereby exciting a sample of the exhaust gases located within the extension or dead end to create an optical emission which can be monitored through the window; and a vacuum pump having an inlet connected to the sub-chamber at the pumping port so as to extract gases from the process chamber through the orifice of the pumping port.