1-nm High Resolution Scanning Spreading Resistance Microscope and its Application to LSI Devices
Abstract: With the rapid scaling down into nanoscale of LSI devices, the fabrication process becomes more and more difficult. Therefore, the requirement for 2D/3D high resolution and precise characterization are becoming high for the purpose of process control and also for understanding of device physics in nanoscale. One of the most important characterizations is the 2D profiling of charge carrier. Scanning spreading resistance microscopy (SSRM) is a typical 2D-profiling metrology, which is one of the applications of conductive atomic force microscopy(C-AFM). SSRM scans on a cross-sectional surface with conductive probe to measure the spreading resistance inside a device in nanoscale, obtaining the 2D-charge-carrier profiles in a short time. In this paper, we demonstrate the significant spatial resolution improvement of SSRM by decreasing of contact resistance between sample and probe with measuring in high vacuum. The fabrication process and measuring sequence of SSRM measurements are also explained. We also demonstrate the 1-nm spatial resolution of SSRM in carrier profiling by comparison with the 3-D device simulation. Applications to failure analysis of CMOSFETs clarified the impact of halo-carrier profiles on Vth-roll-off characteristics.
Key words: SSRM, 2D-carrier profiling, contact resistance, CMOSFET, high resolution