Patent ID: 6156654
Filing Date: 2000-12-05
Classification: H01L

Abstract:
A method of pulsed laser salicidation for the fabrication of ultra-thin suicides on a silicon substrate, comprising the steps of:providing metal-oxide semiconductor field-effect structures on a silicon wafer each with a polysilicon gate electrode with tetraethyl orthosilicate (TEOS) glass or silicon nitride as sidewall spacers, source/drain active junctions defined and field oxidation in the form of shallow trench isolation (STI);providing selective epitaxial growth (SEG) of silicon ranging in thickness from 300 to 400 .ANG. on said gate electrode and said source/drain;cleaning said wafer with diluted HF or in-situ back-sputter with argon;sputter depositing a titanium (Ti) layer to a thickness ranging from 200 to 300 .ANG. on top of said wafer;sputter depositing a titanium-nitride (TiN) cap-layer with a thickness ranging from 150 to 200 .ANG. on top of said Ti layer;forming a phase C49 silicide by providing a react anneal of said Ti layer with a pulsed laser, the wavelength of said pulsed laser chosen such that the irradiation will be mostly absorbed by said Ti layer, the optical fluence, or laser energy, of said pulsed laser ranging from 0.09 to 0.15 J/cm.sup.2 and having a pulse duration ranging from 15 to 30 nanoseconds;wet etching said wafer to clean away said TiN cap layer and any unreacted Ti layer from said polysilicon gate electrodes and said silicon source/drain active junctions; andproviding a final anneal using a pulsed laser with an optical fluence ranging from 0.1 to 0.2 J/cm.sup.2 to convert said Ti layer from said phase C49 silicide into stoichiometric phase C54 titanium silicide (TiSi.sub.2) ranging in thickness from 300 to 400 .ANG..