Sensors for semiconductor processing tools

A system, comprising:

• a vacuum chamber;
• a showerhead within the vacuum chamber;
• a pedestal within the vacuum chamber below the showerhead, the pedestal comprising a sensor compartment;
• a waveguide temperature sensor within the sensor compartment, wherein the waveguide temperature sensor comprises at least one temperature sensor, wherein the at least one temperature sensor comprises a first reflector structure and a second reflector structure, and wherein the first reflector structure and the second reflector structure are separated by a gauge length, wherein the at least one temperature sensor is collocated within the sensor compartment to coincide with one or more measurement locations;
• and
• a transducer coupled to a terminal lead of the waveguide temperature sensor.

A method for measuring temperatures of a process, comprising:

• coupling a signal pulse into a waveguide temperature sensor within a pedestal assembly, wherein the waveguide temperature sensor comprises a temperature sensor, wherein the temperature sensor comprises a first reflector structure and a second reflector structure, and wherein the first reflector structure and the second reflector structure are separated by a gauge length;
• receiving a first return signal and a second return signal reflected from the first reflector structure and the second reflector structure, respectively;
• measuring a first time-of-flight (TOF) of the first return signal and a second TOF of the second return signal;
• calculating a difference between the second TOF and the first TOF;
• and
• correlating the difference with a temperature of one or more surfaces.