• Wavelength Range: UV to Visible to NIR (e.g., 200nm – 800nm) depending on the material being monitored.
• Fiber Optic Cable: High-transmission, UV-grade silica fibers with vacuum feedthroughs.
• Sampling Rate: High-speed acquisition (up to kHz rates) to capture fast endpoint transitions.
• Software Algorithms: Pattern recognition and derivative analysis to identify “Endpoint” automatically.

Functional Features:

• Real-Time Monitoring: Provides real-time feedback on the etch or polish rate and remaining film thickness.
• Process Control: Automatically stops the process the instant the target layer is cleared (Endpoint), preventing over-etch (damage to underlying layers) or under-etch.
• Fault Detection: Detects process excursions (e.g., loss of plasma, incorrect gas flow) by analyzing spectral signatures.
• Multi-Wavelength: Capable of monitoring multiple species simultaneously (e.g., monitoring CO/CO2 ratio for photoresist strip, or F/Cl radicals for oxide etch).
• Run-to-Run Control: Feeds data back to the main controller to adjust process times for subsequent wafers.

Application Scenarios:

• Contact Etch Stop: Detecting the transition from oxide to silicon to stop the etch precisely on the silicon surface.
• Poly-to-Gate Stop: Stopping the gate etch when the polysilicon layer is cleared without damaging the gate oxide.
• CMP Endpoint: Using laser interferometry to detect when the oxide layer is gone and the underlying nitride stop layer is reached.
• Chamber Seasoning: Monitoring the “seasoning” of a chamber by tracking the stabilization of emission byproducts.
• High-k Metal Gate: Precise control of work-function metal etching.