Application of inline high resolution x-ray diffraction in monitoring Si/SiGe and conventional Si in SOI fin-shaped field effect transistor processes

This study investigates the application of inline high resolution x-ray diffraction (HRXRD) for process control of Si/SiGe and conventional Si on silicon-on-insulator (SOI) fin-shaped field effect transistors (FinFETs). HRXRD measurements were taken from test pads on production wafers; the process stages under study were pre- and post-fin etch. For the pre-etch stage, HRXRD monitors the Si or Si/Ge thickness, Ge concentration (%), and crystal quality. For thickness, HRXRD results matched the fin height from a corresponding device within 2 A. When equipped with a 1D detector, the typical measurement time can be as short as 20 min. In the post-etch stage, HRXRD monitors fin pitch with a precision of 3 nm. The choice of diffraction plane has an impact on the signal-to-noise ratio. In particular, the asymmetric 113 reciprocal space map (RSM) has better signal-to-noise than 004 for monitoring Si fins; however, pitch data obtained from these two diffraction planes matches within the measurement precision. The e...