Oxygen Gettering in Transition Metals for Stable Low Barrier Height Schottky Diodes
Original Publication Date: 1978-Aug-01
Included in the Prior Art Database: 2005-Feb-21
One of the major sources of instability in Schottky contacts is contamination (oxygen and carbon) at the metal-Si interface. The increase in Schottky barrier height from 0.4-0.5 eV to 0.55-0.66 eV can be related to oxygen (metal oxide) at metal-Si interfaces. This is shown in Figs. 1 and 2 which depict Auger depth profiles of a Ta Schottky barrier diode (SBD) structure having a low oxygen level in Ta before anneal (Fig. 1) and after anneal (Fig. 2). Note that Phi(B) is 0.46 eV before anneal (Fig. 1) and 0.46 eV after 500 Degrees C - 1 hr. (Fig. 2). For comparison, if the oxide content is high at the Ta-Si interface, e.g., where Phi(B) is 0.62 eV after anneal as compared to 0.59 eV before anneal, removal or stabilizing the oxide content in Ta or other transition metals is desirable to control Phi(B).