Proximity Gettering Design of Hydrocarbon–Molecular–Ion–Implanted Silicon Wafers Using Dark Current Spectroscopy for CMOS Image Sensors

Abstract

We developed silicon epitaxial wafers with high gettering capability by using hydrocarbon–molecular–ion implantation. These wafers also have the effect of hydrogen passivation on process-induced defects and a barrier to out-diffusion of oxygen of the Czochralski silicon (CZ) substrate bulk during Complementary metal-oxide-semiconductor (CMOS) device fabrication processes. We evaluated the electrical device performance of CMOS image sensor fabricated on this type of wafer by using dark current spectroscopy. We found fewer white spot defects compared with those of intrinsic gettering (IG) silicon wafers. We believe that these hydrocarbon–molecular–ion–implanted silicon epitaxial wafers will improve the device performance of CMOS image sensors.

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

“…The white spot defects shown in Figure 4a of both the C 3 H 6 -ion-implanted single and double epitaxial Si wafers were lower than that of the epitaxial Si wafer without implantation. The white spot defects of the single epitaxial Si wafer, compared to that of the IG-enhanced epitaxial Si wafer, was in good agreement with a previous study in which dark current was evaluated to exceed 100 electrons/s [16]. However, the reduction in white spot defects of the double epitaxial Si wafer was the largest among gettering techniques.…”

“…Our research group has been developing novel gettering Si wafers by a hydrocarbon-molecular-ion implantation technique using C 3 H 5 or C 3 H 6 ions to improve the electrical performance of CMOS image sensors [ 14 , 15 , 16 ]. The novel gettering Si wafers comprise an epitaxial Si wafer implanted with hydrocarbon molecular ions in the Czochralski (CZ)-Si substrate.…”

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].…”