Study on dopant activation and EOT impact in HKMG stacks using microwave annealing with different frequencies

Abstract

Abstract In this paper, we have examined the dopant activation levels in various materials (Si, SiGe, and Ge) annealed using two different microwave annealing (MWA) frequencies, 2.45 GHz and 5.8 GHz, with rapid thermal annealing serving as a comparative counterpart. The aim is to identify a material-specific annealing method that minimizes the high thermal budget typically required in the annealing process. For the dopant activation of Si wafer with B doping, there are two different frequencies (2.45 GHz and 5.8 GHz) MWA methods were compared. As the results of electrical measurement, the high activation level by 5.8 GHz MWA shows the material-targeted annealing method to reduce the thermal budget of the device. Additionally, we fabricated a high-k/metal gate (HKMG) MOSCAP structure, which was annealed using 2.45 GHz and 5.8 GHz MWA as part of the post-metallization annealing process. The results show that MWA at 2.45 GHz is more efficient than HF 5.8 GHz MWA at 3000 W in minimizing the interface trapped charge and the reduction in leakage current density. The highest capacitance (1.73 μF cm−2) was observed for MWA 2700 W at 2.45 GHz. However, there is a slight clear reduction in capacitance as the frequency increased to 5.8 GHz increasing in interfacial layer thickness. The post-metallization annealing of gate-last MOSCAPs using MWA at 2.45 GHz not only inhibits the growth of the equivalent oxide thickness and Al diffusion but also preserves the effects of pre-thermal annealing on doping activation at 5.8 GHz. Due to undesirable effects such as Al diffusion into the dielectric layer, the MWA at 5.8 GHz and 2.45 GHz demonstrates great a potential candidate, respectively as doping activation and as a post-metallization annealing method for HKMG structures.