Molecular and Atomic Hydrogen Diffusion Behavior by Reaction Kinetic Analysis in Projection Range of Hydrocarbon Molecular Ion for CMOS Image Sensors

Abstract

In this study, two types of hydrogen diffusion behavior in the projection range of a hydrocarbon molecular ion after high-temperature heat treatment for the passivation of interface state defects at SiO 2 /Si interface of the CMOS image sensor is presented. The hydrogen peak concentration in the hydrocarbon ion projection range is observed by secondary ion mass spectrometry analysis after silicon epitaxial growth and the subsequent high-temperature heat treatment. Moreover, the hydrogen peak concentration strongly depends on heat treatment time after epitaxial growth and the subsequent heat treatment. Two dissociation activation energies by reaction kinetic analysis using the results of the time dependence of hydrogen diffusion behavior are also determined. Assuming two dissociation reactions, the activation energy from the projection range of a hydrocarbon molecular ion is derived. The results of reaction kinetic analysis show that the dissociation activation energies are 0.79 eV for molecular hydrogen and 0.42 eV for atomic hydrogen. The dissociation activation energy of 0.79 eV indicates molecular hydrogen diffusion activation energy, whereas that of 0.42 eV indicates atomic hydrogen diffusion from the projection range of a hydrocarbon molecular ion. Therefore, it is believed that the molecular and atomic hydrogen diffusion behavior of the hydrocarbon molecular ion implanted silicon epitaxial wafers can contribute to the effective reduction in the density of interface state defects at the SiO 2 /Si interface.

Hydrogen passivation for reduction of SiO2/Si interface state density using hydrocarbon-molecular-ion-implanted silicon wafers

“…Indeed, a previous study has demonstrated that the concentration of hydrogen that out-diffused from the C 3 H 5 -implanted region at 700 °C is sufficient compared with D it at the SiO 2 /Si interface. 24) Therefore, we consider that D it at the SiO 2 /Si interface obtained by C-V measurement was reduced owing to the termination of the Si dangling bonds (·Si≡Si 3 ) at the SiO 2 /silicon interface with hydrogen outdiffused from the C 3 H 5 -implanted region.…”

“…Therefore, we have developed an alternative solution to the technical issue encountered in CMOS image sensor fabrication by hydrocarbon molecular ion implantation. [16][17][18][19][20][21][22][23][24] We have demonstrated the fabrication of a novel silicon wafer with three unique characteristics, namely, the high gettering capability for metallic impurities, the oxygen out-diffusion barrier effect and the hydrogen storage effect in the projection range of hydrocarbon molecular ions. We have already reported that our novel silicon wafer leads to a marked improvement of CMOS device key parameters, such as low dark current and white spot defect density when using the CMOS image sensor manufacturing line.…”

“…18) In addition, in a previous study, the diffusion behavior of two types of hydrogen was investigated in the hydrocarbonmolecular-ion-implanted region during isochronal annealing. 24) One is molecular hydrogen (H 2 ) that outdiffused to the silicon lattice from the hydrocarbon-ionimplanted region during annealing below 800 °C. The other is atomic hydrogen (H) that out-diffused to the silicon lattice from the hydrocarbon-molecular-ion-implanted region during annealing above 800 °C.…”

Hydrogen Termination Effect on SiO2/Si Interface State Density in CH3O-Molecular-Ion-Implanted Silicon Epitaxial Wafer for CMOS Image Sensors

“…[9][10][11][12][13][14][15][16][17] We have developed silicon epitaxial wafers by hydrocarbon molecular ion implantation to solve the above-mentioned important technical issues of CMOS image sensors. [18][19][20][21][22][23][24][25][26] Hydrocarbon-molecular-ion-implanted silicon epitaxial wafers have been demonstrated to have high guttering capability for metal impurities generated during the CMOS image sensor manufacturing process. [18][19][20][21][22][23] In addition, to the high gettering capability for metal impurities, the hydrocarbon-molecular-ion-implanted region has unique characteristics.…”

“…For example, it acts as an oxygen diffusion barrier and hydrogen storage. [24][25][26] This hydrocarbon-molecular-ion-implanted silicon epitaxial wafer has been reported to markedly improve important parameters in CMOS image sensors such as dark current and white spot defects. 27 In addition, the reduction in interface state density (D it ) by desorption of hydrogen in the hydrocarbon-molecular-ion-implanted region has been demonstrated by capacitive voltage (CV) measurement and electron spin resonance (ESR) method.…”