A Novel Template Approach by MBE for ALD Growth of High k Dielectrics

Although growth of high k dielectrics by ALD on H-Si is feasible, it undergoes an incubation period during which the formation of SiO2 layer seems inevitable. Recently we showed the MBE growth of HfO2 on Si produced atomically abrupt interfaces, and achieved excellent electrical performance. Here we employed the MBE-grown high k dielectrics thin film as a template to suppress the interfacial layer formation during the ALD growth, and to improve the electrical properties of ALD films. The first demonstration is a bi-layer composite made of a lower HfO2 (MBE) layer 2.5nm thick, and an upper Al2O3 (ALD) film 4.0nm thick. The electrical properties are consistent with the two capacitors in series from two individual dielectric layers. The second demonstration is an MBE and ALD composite Al2O3 6.6nm thick. Studies are underway for the third structure of Al2O3 (MBE) and HfO2 (ALD) composite, which offers dual advantages of interfacial layer suppression and leakage current reduction during HfO2 recrystalization.