Study On Characteristics Of Solid Phase Reaction In Ni/Si(110) System

NiSi, which is widely used in state-of-the-art CMOS devices, is still considered as the most promising contact material for next technology generations, although there are some scaling-induced problems:the deteriorated morphological stability and dramatically increased specific resistance. In order to achieve symmetric CMOSFETs and to enhance the drive current of devices, the attention is paid to Si(110) substrate, which increases the hole mobility while keeping the electron mobility degradation acceptable. In conclusion, it is of paramount importance to study the Ni silicidation on Si(110) substrate, and this paper studies the project from three aspects.1. The study on solid phase reaction in Ni/Si(110) system and the characteristics of NiSi/Si(110) Schottky contact. Both on Si(100) and Si(110) substrates, Ni film is deposited by physical phase deposition (PVD), annealed with Rapid Thermal Annealing (RTA) method in different temperatures to form silicide. By measuring the sheet resistance of the samples annealed in systematic temperatures, the temperature window for the formation of the low-resistive NiSi could be determined. It is found that temperature demanded to form NiSi on Si(110) substrate is higher than that on Si(100) substrate. And the silicide grains are larger on Si(110) substrate, which is shown by the X-ray diffraction (XRD) measurements. Besides, electrical characteristics of NiSi/Si(100) and NiSi/Si(110) are detected by I-V measurement, and the Schottky barrier height (SBH) and ideality factor is extracted by thermal-emission theory. It is shown by the experiment and analysis that there is lower SBH and larger ideality factor for NiSi/Si(110) contact.2. The characteristics of solid phase reaction between ultra-thin Ni film and Si(110) substrate. In this paer, the characteristics of solid phase reaction between ultra-thin (< 5 nm) Ni and p-Si(100) or p-Si(100) substrates is investigated. Sheet resistances of samples with different initial Ni thickness shows that ultra-thin-Ni sample has a stabler morphology than thick one does. Moreover, it is also found that morphological stability on Si(110) substrate is worse than that on Si(100). In addition, there are different silicide growing ways on Ni(5nm)/Si and Ni(10nm)/Si:the preferred orientations of NiSi grains are dependent on intial Ni thickness, as energy minimization demands.3. Sb influence on solid phase reaction of Ni/Si system. A layer of Sb is pre-deposited on Si substrate before the regular deposition of Ni, followed by RTA, to study doped Sb influence on SBH of NiSi/Si. Through secondary ion mass spectrometry (SIMS) measurement, we find Sb segregate near the NiSi/Si interface to form dopant-segregation Schottky (DSS) structure. Expermental data proves that Sb dopant can lower SBH of NiSi/n-Si, and elevate the one of NiSi/p-Si. However, with Sb dopant, NiSi/Si(110) shows a larger reverse current leakage than NiSi/S(100) does, and this may be due to the segregated Sb doesn't prefer to solid-phase-epitaxially (SPE) grow along NiSi/Si(110) interface, which results in a rough interface.