SIMS characterization of ion implanted materials: current status and future opportunities

As the semiconductor industry roadmap passes through the 0.1 μm technology node, the junction depth of the transistor source/drain extension will be required to be less than 20 nm and the well doping will be near 1.0 μm in depth. The performance characteristics and yield of deep sub-micron CMOS devices depends on the ability to control the various input parameters in manufacturing process. High performance parts with good yields requires tight control of film thickness, dose and energy of ion implants, junction depths, contamination levels, and the stoichiometry of deposited films. SIMS has proved valuable in both process development and manufacturing quality control where a high degree of precision and day-to-day reproducibility is required. The development of advanced ULSI processing techniques requires the evolution of new metrology tools to ensure process capability. High sensitivity (ppb) coupled with excellent depth resolution (<1 nm) makes SIMS the technique of choice for measuring the in-depth chemical distribution of these dopants with high precision and accuracy. This paper discusses the current state of the art of SIMS depth profiling as applied to the characterization of ion implanted materials and ultra-shallow doping distributions. Special emphasis is given to the ability of SIMS to make high precision measurements of ion implant depth profiles. In addition, the issues involved in providing artifact free SIMS depth profiling of ultra shallow boron implants are discussed