Effect of low-oxygen-concentration layer on iron gettering capability of carbon-cluster ion-implanted Si wafer for CMOS image sensors

Abstract

The effect of oxygen (O) concentration on the Fe gettering capability in a carbon-cluster (C 3 H 5 ) ion-implanted region was investigated by comparing a Czochralski (CZ)-grown silicon substrate and an epitaxial growth layer. A high Fe gettering efficiency in a carbon-cluster ion-implanted epitaxial growth layer, which has a low oxygen region, was observed by deep-level transient spectroscopy (DLTS) and secondary ion mass spectroscopy (SIMS). It was demonstrated that the amount of gettered Fe in the epitaxial growth layer is approximately two times higher than that in the CZ-grown silicon substrate. Furthermore, by measuring the cathodeluminescence, the number of intrinsic point defects induced by carboncluster ion implantation was found to differ between the CZ-grown silicon substrate and the epitaxial growth layer. It is suggested that Fe gettering by carbon-cluster ion implantation comes through point defect clusters, and that O in the carbon-cluster ion-implanted region affects the formation of gettering sinks for Fe.

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

“…Third, the passivation effect on interface state defects at the SiO 2 /Si interface is expected owing to the hydrogen of hydrocarbon molecular ions trapped in the projection range and diffusing during device thermal processes . Previous studies indicated the gettering capability of these novel silicon epitaxial wafers for metal impurities and the oxygen diffusing from bulk silicon . Furthermore, Yamaguchi demonstrated that these novel silicon epitaxial wafers reduce the dark current due to the interface state defects at the SiO 2 /Si interface.…”

“…These novel silicon epitaxial wafers have three characteristics that can solve the above technical issues leading to the development of advanced CMOS image sensors. First, the projection range of a hydrocarbon molecular ion has a high gettering capability for metallic impurities . Second, the projection range of a hydrocarbon molecular ion also has a barrier effect on oxygen impurities .…”

“…Therefore, we have developed proximity gettering technology using hydrocarbon molecular ion-implanted silicon epitaxial wafers for advanced CMOS image sensors. [18][19][20][21][22][23][24][25] These novel silicon epitaxial wafers have three characteristics that can solve the above technical issues leading to the development of advanced CMOS image sensors. First, the projection range of a hydrocarbon molecular ion has a high gettering capability for metallic impurities.…”

“…First, the projection range of a hydrocarbon molecular ion has a high gettering capability for metallic impurities. [18][19][20][21][22][23] Second, the projection range of a hydrocarbon molecular ion also has a barrier effect on oxygen impurities. [18][19][20][21][22] Third, the passivation effect on interface state defects at the SiO 2 /Si interface is expected owing to the hydrogen of hydrocarbon molecular ions trapped in the projection range and diffusing during device thermal processes.…”

Reduction of Dark Current in CMOS Image Sensor Pixels Using Hydrocarbon-Molecular-Ion-Implanted Double Epitaxial Si Wafers

“…Additionally, we have recently demonstrated that hydrocarbon-molecular-ion implantation in an epitaxial growth layer with a low O concentration, rather than in the CZ-Si substrate, resulted in a higher gettering capability for intentionally contaminated Fe [ 22 ]. It was found that the gettering capability for Fe is determined by the O concentration in the hydrocarbon-molecular-ion implantation region.…”