Improved dimension and shape metrology with versatile atomic force microscopy

Abstract

Accurate, precise, and rapid three-dimensional (3D) characterization of patterning processes in integrated circuit development and manufacturing is critical for successful volume production. As process tolerances and circuit geometries shrink with each technology node, the precision, accuracy, and capability requirements for dimension and profile metrology intensify. The present work adopts the scanning probe based technology, 3D atomic force microscopy (AFM), to address current and next-generation critical dimension (CD) metrology needs for device features at a variety of process steps. Fast, direct, and non-destructive 3D profile characterization of patterning processes is a primary benefit of CD AFM metrology. The CD AFM utilizes a deep trench (DT) mode for narrow and deep trenches, and a CD mode for linewidth and sidewall profiling. The 3D capability enables one tool for many applications where conventional scanning electron microscopy (SEM), scatterometry, and stylus profiler tools fall short: Gate etch/resist linewidth and sidewall cross-section profile, etch depth for high aspect ratio via, STI etch depth, 3D analysis for MUGFET multi-gate devices, pitch/CD/sidewall angle (SWA) verification for scatterometry targets, and post-CMP active recess. The AFM is an efficient tool for inline monitoring, rapid process improvement/development, and is a complementary addition to the dimension metrology family.