Unconsumed precursor monitoring

A monitoring device for monitoring a fabrication process in a fabrication system, the fabrication system comprising a process chamber and a plurality of flow components including an exhaust line or a supply line, and the monitoring device comprising:

• a quartz crystal microbalance (QCM) sensor for monitoring the exhaust line or the supply line of the plurality of flow components of the fabrication system and configured for exposure to a process chemistry in the exhaust line or the supply line during the fabrication process, the QCM sensor comprising a material layer, the material layer being accumulated in situ on the QCM sensor during the fabrication process;
• and
• a controller for:
• measuring resonance frequency shifts of the QCM sensor due to interactions between the QCM sensor and the process chemistry including a precursor gas in the exhaust line or the supply line during the fabrication process for depositing the material of the precursor gas on the wafers;
• and
• determining a parameter of the fabrication process in the process chamber as a function of the measured resonance frequency shifts of the QCM sensor within the exhaust line or the supply line, wherein the exhaust line or the supply line during the fabrication process comprises an unconsumed portion of the precursor gas in the process chamber, and a mass of the QCM sensor changes due to the unconsumed portion of the precursor gas interacting with the material layer of the QCM sensor, and the controller determines the parameter of the fabrication process in the process chamber due to the measured resonance frequency shifts of the QCM sensor indicating the changing mass of the QCM sensor.

A method for monitoring a fabrication process in a fabrication system, the fabrication system comprising a process chamber and a plurality of flow components, and the method comprising:

• deploying a quartz crystal microbalance (QCM) sensor for monitoring one flow component of the plurality of flow components of the fabrication system;
• accumulating a material layer on the QCM sensor in situ during the fabrication process;
• exposing the QCM sensor to a process chemistry in the one flow component during the fabrication process;
• measuring resonance frequency shifts of the QCM sensor due to interactions between the material layer of the QCM sensor and the process chemistry in the one flow component during the fabrication process;
• and
• determining a parameter of the fabrication process in the process chamber as a function of the measured resonance frequency shifts of the QCM sensor within the one flow component.