Selective Titanium Silicide Chemical Vapor Deposition with Surface Cleaning by Silane and Ohmic Contact Formation to Very Shallow Junctions

Abstract

A new method of selective titanium silicide chemical vapor deposition for very shallow junctions is developed. This method includes an in situ silane (SiH~) cleaning treatment which greatly increases titanium silicide nuclei, and a silicon consumption control. Native oxide reduction from the silicon surface by the Sill4 cleaning treatment is confirmed by secondary ion mass spectroscopy measurements. The deperidence of the source-gas flow rate on silicon consumption and film resistivity are clarified. The titanium silicide film properties are evaluated in conjunction with the silicon consumption. By applying thin titanium silicide films to test devices with 0.1-~m-deep shallow junctions, a low contact resistivity of 7 2 ~1 2 around 10- ~-cm and a low leakage current of around 10- A/mm are obtained. The dependence of growth time on contact resistance and leakage current is also clarified. The scaling down of semiconductor devices has resulted in increased switching speed, packing density, and reliabil-ity. However, contact resistance, increases in inverse pro-portion to the square of the contact hole size. Additionally, the aspect ratio of the contact holes has increased because of the scale-down requirements and surface planarization.