AVS 45th International Symposium
    Manufacturing Science and Technology Group Tuesday Sessions
       Session MS-TuA

Paper MS-TuA10
Plasma-Induced Nitridation of the Gate Oxide Dielectrics: Linked Equipment-Feature-Atomic Scale Simulations

Tuesday, November 3, 1998, 5:00 pm, Room 317

Session: Process, Integration, and Modeling
Presenter: V. Sukharev, LSI Logic Corporation
Authors: V. Sukharev, LSI Logic Corporation
S. Aronowitz, LSI Logic Corporation
H. Puchner, LSI Logic Corporation
V. Zubkov, LSI Logic Corporation
J. Haywood, LSI Logic Corporation
J. Kimball, LSI Logic Corporation
Correspondent: Click to Email
Quantum chemical calculations were employed to get insight into the mechanisms involved in plasma-induced nitridation of gate oxide that will suppress boron penetration. The roles played by the nitrogen cations and atoms were explored. Based on these results, we assumed the following model for the nitrogen incorporation: nitrogen cations cleave bonds in substrate subsurface region; the depth of the damaged layer is determined mainly by the energy of the incident ion, binding energy of nitridated material and its density. Nitrogen atoms, whose concentration is usually several orders of magnitude greater than the cation concentrations, readily react with dangling bonds to produce @>=@Si-N- and @>=@Si-O-N- radicals. A subsequent anneal produces an appropriate condition for reaction between the above radicals and results in the nitrogen insertion into the SiO@sub 2@ ring structure. Thus the nitrogen cations play the role of the promoter for the entire SiO@sub 2@ nitridation. It was shown that B interaction with siloxane rings that contain incorporated nitrogen yielded a larger energy gain than rings without nitrogen. This explains the chemical nature of the nitrogen-induced barrier effect. Monte Carlo (PROMIS) simulations were used to simulate the necessary energy of incident N@sub 2@@super +@ cations to produce the bond cleavage down to a particular depth in the amorphous SiO@sub 2@ layer. A combination of the Hybrid Plasma Equipment Model and Plasma Chemistry Monte Carlo Simulation codes were used to simulate nitrogen atomic and cation fluxes and their angular and energy distributions at the wafer surface. Combining simulated cation energies with PROMIS Monte Carlo simulation results make it possible to derive the plasma process parameters that will permit a desired level of nitridation to be reached.