Patent ID: 6242348
Filing Date: 2001-06-05
Classification: H01L

Abstract:
A method for the formation of a boron-doped silicon gate layer underlying a cobalt silicide layer comprising the steps of:providing a PMOS transistor structure comprising:an N-well on a P-type silicon substrate;a gate oxide layer on the N-well; anda silicon gate layer overlying the gate oxide layer;depositing a cobalt layer on the PMOS transistor structure;subjecting the PMOS transistor structure and the cobalt layer to a first thermal treatment to form a bilayer CoSi/silicon stack structure and unreacted cobalt;removing the unreacted cobalt;implanting boron into the bilayer CoSi/silicon stack structure;implanting nitrogen into the bilayer CoSi/silicon stack structure, thereby producing a nitrogen concentration profile in the bilayer CoSi/silicon stack structure with a peak nitrogen concentration located immediately below the CoSi/silicon interface;subjecting the bilayer CoSi/silicon stack structure, implanted boron and implanted nitrogen to a second thermal treatment to form a CoSi.sub.2 layer and to thermally activate the implanted boron, thereby forming a boron-doped silicon gate layer underlying a cobalt silicide (CoSi.sub.2) layer.