Carbon implantation performance improvement by using carbon monoxide (CO) gas on applied materials VIISta HCS implanter

Abstract

Carbon implant has become one of the major co-implant steps in the fabrication of advanced semiconductor devices due to its proven effectiveness in controlling and reducing Transient Enhanced Diffusion (TED) in ultra-shallow junction formation. Carbon dioxide (CO₂) is still widely used as the feed gas for carbon implantation. However, it is well known that the high concentration of oxygen from CO₂ causes many problems, including oxidation of the implant arc chamber components, which leads to rapid performance degradation of the source. Phosphine (PH₃) is often used as a dilution gas to minimize the oxidation effect from CO₂. However, its use usually results in a reduction of the C⁺ beam current, thereby negatively impacting the tool's productivity. In this paper, carbon monoxide (CO) is presented as an alternative carbon doping gas replacing CO₂ or CO₂ with PH₃ dilution (referred to as CO₂/PH₃ throughout this paper). CO is shown to exhibit distinct performance improvements compared to CO₂/PH₃ on the Applied Materials VIISta HCS high current implanter. Significant improvement in C⁺ beam current and source life with CO gas is noted.