Semiconductor gate structure for threshold voltage modulation and method of making same

摘要

A gate structure of a semiconductor device having a NFET and a PFET, includes a lower layer of a hafnium-based dielectric over the gates of the NFET and PFET, and an upper layer of a lanthanide dielectric. The dielectrics are annealed to mix them above the NFET resulting in a lowered work function, and corresponding threshold voltage reduction. An annealed, relatively thick titanium nitride cap over the mixed dielectric above the NFET gate also lowers the work function and threshold voltage. Above the TiN cap and the hafnium-based dielectric over the PFET gate, is another layer of titanium nitride that has not been annealed. A conducting layer of tungsten covers the structure.

主权项

1. A method, comprising:
providing a semiconductor device comprising a n-type transistor and a p-type transistor; creating a first dielectric layer of at least one first dielectric material over the semiconductor device; depositing a first layer of work function material lacking aluminum over the transistors; altering a work function of the first layer of work function material by annealing; and separating work functions of the transistors by removing the first layer of work function material over one of the transistors.