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

An apparatus for etching a sample, said apparatus comprising:

• (a) a source of etchant gas;
• (b) an etching chamber in communication with said source of etchant gas;
• (c) a recirculation loop passing through said etching chamber;
• (d) a pump disposed within said recirculation loop for recirculating etchant gas along said recirculation loop;
• and
• (e) a gas analyzer for analyzing gas components within the recirculation loop.

A method, comprising:

• a) providing a sample to be etched in a chamber;
• b) providing an etchant to the chamber, capable of etching the sample;
• c) providing no or substantially no impedance to gas exiting the etching chamber;
• d) monitoring a partial pressure of an etch product;
• and
• e) repeating steps a) to d) except providing an increased impedance each time steps a) to d) are repeated, until an impedance is reached that allows for determining an endpoint based on monitoring the partial pressure of the etch product.

An apparatus comprising:

• an etching chamber;
• a source of an etchant;
• a gas recirculation loop for recirculating the etchant repeatedly through the etching chamber;
• and
• a gas analyzer within the etching chamber or within the gas flow line downstream of the etching chamber.

A method for etching a sample comprising:

• providing a sample to be etched to an etching chamber;
• providing a vapor phase etchant to the chamber, the vapor phase etchant being a spontaneous chemical etchant, to etch the sample, and passing unreacted vapor phase etchant and etching products out of the etching chamber during the etch;
• monitoring the vapor phase etchant and/or etching product within or coming from the etching chamber during the etch;
• and
• determining the end point of the etch based on said monitoring.

A method for etching a sample, comprising:

• providing a sample to be etched to an etching chamber;
• providing a vapor phase etchant through the chamber to etch the sample, the vapor phase etchant capable of etching the sample in a non-energized state;
• impeding the gas flow out of the etching chamber, wherein the impedance is less than infinity but greater than 0;
• monitoring gas component levels within or coming from the etching chamber;
• and
• determining the end point of the etch based on the monitoring of the gas in or from the etching chamber.

A method for etching a sample comprising:

• providing a sample to be etched to an etching chamber;
• providing a vapor phase etchant through the chamber to etch the sample, the vapor phase etchant capable of etching the sample in a non-energized state;
• monitoring an increase in an etch product over a period of time followed by a decrease in the etch product over a period of time;
• and
• determining the end point of the etch based on the monitoring of the gas.

A method for etching a sample, comprising:

• providing a sample to be etched to an etching chamber that has an optional recirculation loop for recirculating etchant repeatedly through the etching chamber;
• providing a vapor phase etchant through the chamber to etch the sample, the vapor phase etchant capable of etching the sample in a non-energized state and being passed through the etching chamber or recirculation loop at a rate sufficient to cause a production of an etching product faster than an outflow of the etchant product from the etching chamber or recirculation loop;
• monitoring the etching product within the etching chamber or recirculation loop;
• and
• determining the end point of the etch based on the monitoring of the etching product.