Matthew Fenton Davis

Plasma Optimization Usinga Real-Time, Insitu Sensor BASED on Optical and RF Signatures: Advanced ETCH Applications

Summary form only given. A novel in-situ sensor is utilized to characterize the plasma used in conductor etch applications. This real-time sensor employs both full optical spectrum as well as RF sensor input to acquire detailed plasma information. The use of optical emission and reflectance spectrum capture from 200 nm to 800 nm at 10 Hz along with the basic RF harmonics (at the same 10 Hz rate) gives a detailed fingerprint of the plasma which has been found to reveal subtle aspects of plasma, process and chamber conditions. Since the plasma is a complex function of many components, the use of this data-rich approach has been proven to allow detection of features which otherwise would not be apparent. The EyeD process state monitor has been developed as a combination of sensitive detection and advanced principle component analysis in order to extract the maximum amount of relevant information (signal) from the noise. This signal to noise improvement can be greater than many orders of magnitude depending on the application. In particular, the sensor configuration is utilized for conductor etch to study the nature of the plasma under a wide range of tuning conditions. The goal of this activity is to determine a correlation between plasma state and both the input parameters (power, gas flow), as well as boundary conditions (chamber seasoning, process history), and ultimately the on-wafer performance of the plasma for conductor etch. With the use of principle component analysis, it is possible to evaluate a extremely complex plasma condition and reduce the data to a set of 2-3 relevant components. With these components, the plasma condition can be quantitatively monitored and evaluated. This ability allows for multiple capabilities which will be highlighted in the paper. Data will be given showing how the plasma conditions can be used for: process optimization (stability, ignition window, higher etch rate, etc.); for hardware optimization (chamber baselining, chamber to chamber matching, excursion detection, fault capture and analysis); and sequence optimization (seasoning, switching between etch conditions and materials). This in-situ, real-time capability enables plasma diagnostics and APC. Examples include various advanced conductor etch processes