Suicides have been long used to solve the problem of poly depletion effects in the CMOS circuits. The depletion layer in the poly-gates increases the total effective gate-dielectric thickness causing a poor device performance. Many advantages are promised in replacing the Polysilicon gates with metal gates, which include improved sheet resistance of the gates, decreased equivalent electrical thickness of gate dielectric by eliminating the Polysilicon gate depletion effect, and dual work functions, higher than n+ poly work function for NMOS and lower than p+ poly for PMOS in a single full Silicidation (FUSI) of Polysilicon gates. In the ever reducing gate dimension and junction depths, nickel Suicide has become one of the promising candidates for silicides applications in submicron CMOS devices. Nickel silicides has many advantages over other metal silicides due to its one step low temperature formation, low resistivity (14~20 μΩcm), low Si consumption, and its nature of not suffering from resistivity degradation on narrow lines or gates. However, nickel suicides have some problems associated with them such as the large junction leakage current and sheet resistance degradation due to oxygen contamination and rough interface between NiSi and Si. Nickel Silicide was formed on doped Polysilicon to simulate the effects on gate CMOS regions. Sheet resistance will be measured on silicided Polysilicon and results will be introduced in this report as well.
Alshehri, Yaser A.
"Development of a Full Silicidation (FUSI) Process for Nickel Silicide,"
Journal of the Microelectronic Engineering Conference: Vol. 14
, Article 10.
Available at: http://scholarworks.rit.edu/ritamec/vol14/iss1/10