A Review of Proximity Gettering Technology for CMOS Image Sensors Using Hydrocarbon Molecular Ion Implantation

Abstract

We developed a high-gettering-capability silicon wafer for advanced CMOS image sensors using hydrocarbon molecular ion implantation. We found that this novel silicon wafer has an extremely high gettering capability for metal, oxygen, and hydrogen impurities during the CMOS device fabrication process. We also found that the white spot defect density of a hydrocarbon-molecular-ion-implanted CMOS image sensor was substantially lower than that of a CMOS image sensor without hydrocarbon molecular ion implantation. This indicates that the novel silicon wafer helped improve device performance parameters such as white spot defect density and dark current. We believe that this wafer will be beneficial in the design of silicon wafers for advanced CMOS image sensor fabrication.

Silicon Wafer Gettering Design for Advanced CMOS Image Sensors Using Hydrocarbon Molecular Ion Implantation: A Review

“…We found that this novel silicon wafer has three unique silicon wafer characteristics. The first is, its very high gettering capability for metallic impurities in the pixel active region during CMOS image sensor fabrication process [12], [13]. The second is, its oxygen out-diffusion barrier effect, which presents oxygen from out-diffusing to the device active region from the CZ silicon substrate during device heat treatment [14].…”

Dissociation Kinetics of Trapped Hydrogen in High-dose Hydrocarbon-Molecular-Ion-Implanted Silicon during Rapid Thermal Annealing

“…To resolve the above technical issues, we developed an epitaxial silicon wafer in which we introduced proximity gettering sinks by a hydrocarbon molecular ion implantation technique [15,16]. Kurita and coworkers presented three unique characteristics of a hydrocarbon-molecular-ion-implanted epitaxial silicon wafer to improve the electrical device performance of CMOS image sensors [17][18][19][20][21][22]. First, the hydrocarbon-molecularion-implanted region has high gettering capability for various heavy metallic impurities [17][18][19][20][21][22][23][24][25].…”

“…Kurita and coworkers presented three unique characteristics of a hydrocarbon-molecular-ion-implanted epitaxial silicon wafer to improve the electrical device performance of CMOS image sensors [17][18][19][20][21][22]. First, the hydrocarbon-molecularion-implanted region has high gettering capability for various heavy metallic impurities [17][18][19][20][21][22][23][24][25]. The gettering technique has been widely used as a processing technique that can eliminate heavy metallic impurities diffused to the device active region during CMOS device fabrication process in semiconductor manufacturing.…”

“…This technique can markedly improve electrical device performance such as pn-junction leakage current, oxide breakdown voltage characteristics, and white spot defect density by capturing the metallic impurity at gettering sites formed outside the device active region during CMOS device fabrication process [26]. Second, this implanted region also has a diffusion barrier to prevent oxygen impurities diffusing out to the device active region from the silicon substrate during the fabrication of CMOS image sensors [17][18][19][20][21][22]. Third, hydrogen in hydrocarbon molecular ions trapped in the ion-implanted region diffuses to processinduced defects such as interface state defects at the SiO 2 /Si interface and is expected to cause the passivation effect [17-22, 27, 28].…”

Reduction of White Spot Defects in CMOS Image Sensors Fabricated Using Epitaxial Silicon Wafer with Proximity Gettering Sinks by CH2P Molecular Ion Implantation

“…Kurita and coworkers demonstrated that the three characteristics of C 3 H 5 -molecular-ion-implanted epitaxial silicon improved electrical performance, such as the reduction in the number of white spot defects and dark currents in CMOS image sensors as determined by dark current spectroscopy (DCS) [ 25 , 26 ]. DCS is a powerful metallic impurity contamination analysis method, which enables us to count generated dark currents in pixels in charge-coupled devices (CCDs) and CMOS image sensors [ 7 , 27 , 28 , 29 ].…”