Interfacial Defects Induced by Silicidation and Effects of H-Termination at Metal/Silicon Contacts

Abstract

We have investigated crystallographic structures and electrical properties at the interfaces of transition metals such as Ti, Zr, Hf and V and Si(100), from the viewpoint of an application to ohmic contacts in future ULSI's with low contact resistivity and high reliability. We have achieved very low contact resistivities of 3-5x10-8 Qcm 2 for Zr/ and Hf/n+-Si(100) contacts and 1-2x1O-7 Qcm 2 for p+-Si at 400-600 0 C. It is found that the silicidation reaction in this temperature range brings about the formation of deep levels associated with vacancies in Hf/Si and with metal atoms in V/Si. This difference is considered to be related to that in the silicide formation process between these systems. Furthermore, an anomalous electrical characteristics observed for Hf/p-Si contacts has been found to be markedly improved by using a H-termination treatment of Si surfaces.

Low-resistance titanium/n-type silicon (1 0 0) contacts by monolayer selenium passivation

“…The actual barrier height, however, is largely independent of metal work function or semiconductor electron affinity due to Fermi level pinning by interface states [3]. On the other hand, Schottky barrier height and contact resistance can be affected by both material factors (metal or silicide [4], doping level [5] and crystal structure [6]) and processing conditions (surface cleaning [7,8], oxide layer [9], annealing [10,11] and passivation [12]) because of their interface sensitivity.…”

Low-resistance Ti/n-type Si(100) Contacts by Monolayer Se Passivation

“…The actual barrier height, however, is largely independent of metal work function due to Fermi level pinning by interfacial states. On the other hand, Schottky barrier height and contact resistance can be affected by both material factors (metal or silicide (3), doping level (4), and crystal structure (5)) and processing conditions (surface cleaning (6,7), oxide layer (8), annealing (9,10), and passivation (11)) because of their interface sensitivity. effect is believed to be the result of minimized interface states when Se atoms form strong bonds with unsaturated Si atoms on the (100) surface to terminate the dangling bonds (14).…”

Interfacial reactions of Ti/ and Zr/Si1−xGex/Si contacts with rapid thermal annealing

“…We have systematically investigated the solid-phase reactions and electrical properties of transitionmetal/Si(100) systems, in which contact resistivities as low as 10 -8 cm 2 have been reported for Zr/ and Hf/n + -Si(100) contacts [2][3][4][5]. However, there are some limitation factors, such as the bandgap, the electron affinity and the solid solubility of impurity atoms in Si, for achieving much lower contact resistivity.…”