Method for the selective deposition of tungsten on a silicon surface

Claim 1

A method for the selective deposition of tungsten on a silicon surface comprising the steps of: providing the silicon surface with a masking structure composed of SiO 2 ; implementing deposition of tungsten from a vapor phase in a chemical vapor deposition (CVD) reactor from a mixture of process gases containing H 2 and WF 6 such that the masking structure remains essentially free of tungsten; and calculating the process parameters of temperature, pressure and flow-through rates of the process gases for the selective deposition for a prescribed deposition rate by iteratively solving an equation system using different values of temperature, pressure and flow-through rates until a preselected value of the prescribed deposition rate of tungsten on the silicon surface is achieved, and using in the equation system conservation laws for mass, for chemical constituents participating in the deposition reaction, for momentum and for energy, and taking into consideration in the equation system boundary conditions of the CVD reactor and effects of thermodiffusion and multi-constituent diffusion, the equation system consisting of the following equations; ##EQU4## where ρ is density in the medium, m i is mass fraction of a particle i, t is time, v is velocity, D ij is a coefficient for multi-constituent diffusion, D T i is a coefficient for thermodiffusion, T is temperature, G i is generation rate of the particle i, j WFx is flow of WF x , k 1= 10 -5 kg/(ms), ⊖ is portion of the surface that is covered with tungsten, k 2= 10 -3 kg/(ms), n is a nucleation rate per surface unit, k 3= 10 13 s -1 m -2 , R w is a deposition rate of tungsten, ρ w is density of the CVD tungsten, D WF6 is a diffusion coefficient of WF 6 in H 2 under operating conditions, N' WF6 is a concentration of WF 6 at a location under consideration, δ is a distance of the location from the silicon surface, P H2 is a pressure of H 2 , k 0= 4.08×10 6 (nm min -1 Pa -1/2 ), E a is activation energy, WF 6 is a mass fraction of the particle WF 6 ,and WF x is a mass fraction of the particle WF x ; and depositing tungsten on said silicon surface at the prescribed deposition rate using the process parameters of temperature, pressure and flow-through rates that were calculated by iteratively solving the equation system.

Claim 2

A method for the selective deposition of tungsten on a silicon surface comprising the steps of: providing the silicon surface with a masking structure composed of SiO 2 ; implementing deposition of tungsten from a vapor phase in a chemical vapor deposition (CVD) reactor from a mixture of process gases containing H 2 and WF 6 such that the masking structure remains essentially free of tungsten; and calculating the process parameters of temperature, pressure and flow-through rates of the process gases for the selective deposition for a prescribed deposition rate by iteratively solving an equation system using different values of temperature, pressure and flow-through rates until a preselected value of the prescribed deposition rate of tungsten on the silicon surface is achieved, and using in the equation system conservation laws for mass, for chemical constituents participating in the deposition reaction, for momentum and for energy, and taking into consideration in the equation system boundary conditions of the CVD reactor and effects of thermodiffusion and multi-constituent diffusion, the equation system consisting of the following equations; ##EQU4## where ρ is density in the medium, m i is mass fraction of a particle i, t is time, v is velocity, D ij is a coefficient for multi-constituent diffusion, D T i is a coefficient for thermodiffusion, T is temperature, G i is generation rate of the particle i, j WFx is flow of WF x , k 1= 10 -5 kg/(ms), ⊖ is portion of the surface that is covered with tungsten, k 2= 10 -3 kg/(ms), n is a nucleation rate per surface unit, k 3= 10 13 s -1 m -2 , R w is a deposition rate of tungsten, ρ w is density of the CVD tungsten, D WF6 is a diffusion coefficient of WF 6 in H 2 under operating conditions, N' WF6 is a concentration of WF 6 at a location under consideration, δ is a distance of the location from the silicon surface, P H2 is a pressure of H 2 , k 0= 4.08×10 6 (nm min -1 Pa -1/2 ), E a is activation energy, WF 6 is a mass fraction of the particle WF 6 ,and WF x is a mass fraction of the particle WF x ; and depositing tungsten on said silicon surface at the prescribed deposition rate using the process parameters of temperature, pressure and flow-through rates that were calculated by iteratively solving the equation system.