Band alignment of high-к/SiO2/Si stacks incorporating Zr and Al oxides prepared by atomic layer deposition

Band alignment of high-κ/SiO₂/Si stacks incorporating Zr and Al oxides for advanced MOS technology is explored. Because of requirements concerning continued scaling of MOSFET transistors, gate oxides were grown in situ on Si(001) substrate by means of atomic layer deposition (ALD) process using respectively TDMAZr and TMA as metal precursors and ultra pure H₂O as oxygen source. The thicknesses of high-κ films were around 1-2 nm. We applied synchrotron radiation based X-ray photoelectron spectroscopy (SR XPS) at the undulator beam line U49/2-PGM2 (BESSY, Berlin) to characterize our samples, which allows step by step in situ investigations. In this way thanks to our (in situ)² approach we are able to improve functional properties of our thin films by controlling sample preparation process. Si 2p, O 1s, Zr 3d, Al 2p core levels and valence band (VB) spectra were recorded and analyzed. As a result, we determined chemical composition, growth rate and electronic band structure. We found the formation of interface dipole as well as the existence of space charge regime as deduced from continuous shift of the VB maximum with increasing layer thickness.