Effect of surface NH3 anneal on the physical and electrical properties of HfO2 films on Ge substrate

Abstract

Metal-oxide-semiconductor capacitors were fabricated on germanium substrates by using metalorganic-chemical-vapor-deposited HfO2 as the dielectric and TaN as the metal gate electrode. It is demonstrated that a surface annealing step in NH3 ambient before the HfO2 deposition could result in significant improvement in both gate leakage current and the equivalent oxide thickness (EOT). It was possible to achieve a capacitor with an EOT of 10.5 Å and a leakage current of 5.02×10−5 A/cm2 at 1 V gate bias. X-ray photoelectron spectroscopy analysis indicates the formation of GeON during surface NH3 anneal. The presence of Ge was also detected within the HfO2 films. This may be due to Ge diffusion at the high temperature (∼400 °C) used in the chemical-vapor deposition process.

Ge incorporated epitaxy of (110) rutile TiO2 on (100) Ge single crystal at low temperature by pulsed laser deposition

“…These properties cause high defect densities at the interface between high-k and Ge and a large hysteresis in the capacitance-voltage (C-V) characteristic [8,9]. To overcome these problems, some groups have demonstrated the formation of stable GeO 2 [10,11] and the surface passivation of Ge such as GeN (GeON) passivation [12,13], Si passivation [14], and F passivation [15]. These approaches achieved the improvements of electrical properties such as reduced C-V characteristic hysteresis and reduced leakage current.…”

Nature of the interface of (100)Ge/insulator structures with ultrathin HfO2 and GeOx(Ny) layers probed by electron spin resonance

“…Pertinently, we may notice that no such signal is observed in the Si/HfO 2 structures prepared using similar surface preparation and deposition procedures indicating that the originating defects likely pertain to the GeO x N y interlayer. However, here one could object the signal to have arisen from Ge diffusion [16] into the HfO 2 layer during its deposition at 485 • C. (d) One more remarkable observation is that the ESR signal observed in the as-deposited and VUV-exposed samples is hardly affected by treatment in H 2 at 400 • C. A close defect density and the same g-value are observed after heating in H 2 (spectra not shown) bearing out these defects to be resistant to passivation by hydrogen at 400 • C, quite in contrast with the behavior of Si DB (P b ) type defects. (e) Finally, in contrast to passivation by H, the oxidizing PDA strongly affects the ESR spectra (not shown) of Ge/HfO 2 .…”

Impacts of Ti on electrical properties of Ge metal–oxide–semiconductor capacitors with ultrathin high-k LaTiON gate dielectric

“…ZrO 2 [1], HfO 2 [2][3][4], and Al 2 O 3 [5]) are extensively discussed as alternative candidates for future complementary MOS technology due to the high carrier mobilities of germanium [6][7][8]. However, the growth of unstable and water-soluble germanium oxide during deposition and post-deposition annealing hinders the fabrication of competitive Ge-based MOS devices [9,10]. To overcome this problem, various techniques including NH 3 surface treatment [2][3][4][5] and Si interlayer [11,12] have been applied in Ge-based MOS devices to enhance device performances.…”