Proximity gettering of C₃H₅ carbon cluster ion-implanted silicon wafers for CMOS image sensors: Gettering effects of transition metal, oxygen, and hydrogen impurities

Abstract

A new technique is described for manufacturing silicon wafers with the highest capability yet reported for gettering transition metallic, oxygen, and hydrogen impurities in CMOS image sensor fabrication. It is demonstrated that this technique can implant wafers simultaneously with carbon and hydrogen elements that form the projection range by using hydrocarbon compounds. Furthermore, these wafers can getter oxygen impurities out-diffused from the silicon substrate to the carbon cluster ion projection range during heat treatment. Therefore, they can reduce the formation of transition metals and oxygen-related defects in the device active regions and improve electrical performance characteristics, such as dark current and image lag characteristics. The new technique enables the formation of high-gettering-capability sinks for transition metals, oxygen, and hydrogen impurities under device active regions of CMOS image sensors. The wafers formed by this technique have the potential to significantly reduce dark current in advanced CMOS image sensors.

Proximity gettering technology for advanced CMOS image sensors using carbon cluster ion‐implantation technique: A review

“…In our previous study , it was found that a carbon cluster ion implanted silicon wafer had three characteristics for high performance of advanced CMOS image sensors. First, a carbon cluster ion projection range has high gettering ability of metallic impurities during heat treatment . Second, this projection range also has a diffusion barrier effect for oxygen impurities out‐diffusing to the device active regions from the CZ grown silicon wafer substrate .…”

Effect of dose and size on defect engineering in carbon cluster implanted silicon wafers

“…[14][15][16] Second, this implanted region of carbon clusters also has a barrier effect on oxygen impurities diffusing out from the Si wafer bulk. 14,15) Third, a passivation effect on process-induced defects is expected owing to the hydrogen in the carboncluster ions trapped in the implanted region during the device fabrication process. 16,18) However, the formation behavior of the implantation defects considered to be the gettering sinks in the implanted region around the projection range of the carbon clusters is unclear.…”

“…Furthermore, we demonstrated that carbon-cluster-ion-implanted epitaxial wafers have three characteristics useful for achieving high-performance advanced CMOS image sensors. [14][15][16] First, the silicon surface within the projection range of carbon clusters has a high gettering capability for metallic impurities. [14][15][16] Second, this implanted region of carbon clusters also has a barrier effect on oxygen impurities diffusing out from the Si wafer bulk.…”

“…[14][15][16] First, the silicon surface within the projection range of carbon clusters has a high gettering capability for metallic impurities. [14][15][16] Second, this implanted region of carbon clusters also has a barrier effect on oxygen impurities diffusing out from the Si wafer bulk. 14,15) Third, a passivation effect on process-induced defects is expected owing to the hydrogen in the carboncluster ions trapped in the implanted region during the device fabrication process.…”

“…We previously developed a proximity gettering technique by performing carbon-cluster-ion implantation in silicon wafers. [14][15][16] Carbon-cluster ions can be obtained by the decomposition of a source gas containing carbon and hydrogen. For example, we can use C 5 H 5 or C 3 H 5 .…”