Abstract:
Using a method of high-frequency magnetron sputtering, the structures W(150 nm)/HfO$_2$(5 nm)/Si(100) were prepared and were further annealed either at 500$^\circ$C in vacuum for 30 min or in an atmosphere of argon at 950$^\circ$C for 12 s. Study of the capacitance-voltage characteristics of these structures showed that high-temperature annealing leads to a decrease in the maximum specific capacitance in accumulation (from 4.8 $\cdot$ 10$^{-6}$ to 3.2 $\cdot$ 10$^{-6}$ F/cm$^2$) and dielectric constant (from 27 to 23). Using time-of-flight secondary-ion mass spectrometry, it is established that growth of a WO$_x$ phase at the W/HfO$_2$ interface and a HfSi$_x$O$_y$ silicate phase at the HfO$_2$/Si (100) interface occurs during annealing. In addition, the total thickness of the intermediate oxide layer exceeds the thickness of the initial HfO$_2$ film by 30%.
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