Method for removing photoresist from photomask substrate

A computer-readable storage medium storing a program, which, when executed by a processor performs an operation for operating a processing chamber, the operation comprising:

• collecting first signals at an OES detector, the first signals emitted from a surface of a photomask substrate during removal of a first portion of photoresist from the photomask substrate;
• analyzing the collected first signals to determine a state of a first reactive species distributed across the surface of the photomask substrate;
• determining a first photoresist removal recipe in response to the analysis of the collected first signals, wherein the first photoresist removal recipe includes adjusting a first gas mixture used to perform plasma etching of the first portion, and wherein the first photoresist removal recipe includes a first endpoint;
• and
• collecting second signals at the OES detector, the second signals emitted during removal of a second portion of photoresist from the photomask substrate, wherein the second portion is a residual of the first portion;
• analyzing the collected second signals to determine a state of a second reactive species distributed across the surface of the photomask substrate;
• determining a second photoresist removal recipe in response to the analysis of the collected second signals, wherein the second photoresist removal recipe includes adjusting a second gas mixture used to perform etching of the second portion, and wherein the second photoresist removal recipe includes a second endpoint;
• determining a first endpoint based upon an intensity of the first signals;
• determining a second endpoint based upon an intensity of the signals;
• and
• removing the first portion based upon the first endpoint and removing the second portion based upon the second endpoint.