Real-time in-situ chemical sensing, sensor-based film thickness metrology, and process control in W CVD process

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A real-time in-situ sampling system has been implemented for chemical sensing in tungsten chemical vapor deposition process (W-CVD) using mass spectrometry. Sensor integration was realized to allow synchronous capture of equipment state signals and process signals (chemical information from mass spectrometry).

Wafer state metrology from integrated mass spectrometry signals of different gaseous chemical species in the reaction was established with an uncertainty of 2-7 percent depending on the conversion rate of the process, which is determined by the process chemistry and processing conditions. The mass spectrometry-based wafer state metrology obtained was applied to implement fault detection and W film thickness process control: run-to-run control in H2 reduction W-CVD and real time end point control in SiH4 reduction process.

The results demonstrate the benefit of combining real-time mass spectrometry sensor data with equipment state information for process control. The important generic issues regarding real-time in-situ chemical sensing using mass spectrometry in the context of a multi-component chemical reaction system like W-CVD have also been discussed.

The accomplishments of this research demonstrate the value of in-situ chemical sensing in complex manufacturing process systems and provide clear pathways toward advanced process control methodology.