Thermal stability and scalability of Zr-aluminate-based high-k gate stacks

It is demonstrated that a narrow composition range exists in the ZrAl/sub x/O/sub y/ mixed oxide system between 25 and 50 mol% Al/sub 2/O/sub 3/, where the crystallization temperature exceeds 950/spl deg/C and at the same time the k-values remain larger than 12. In this composition range, enhanced thermal stability for better integration of the ZrAl/sub x/O/sub y/ gate dielectric in a conventional poly-Si device process is observed. It is also shown that thin interfacial oxides strongly enhance the electrical stability while allowing for thickness scaling down to /spl sim/1 nm, providing gate leakage current reductions of two to three orders of magnitude.