Application of ALD W films as gate filling metal in 22 nm HKMG-last integration: Evaluation and improvement of the adhesion in CMP process

摘要

Basic material properties and trench filling capability of different W films prepared by CVD and ALD (SiH4 and B2H6-based) are evaluated on blank and patterned wafers respectively in this work. As-prepared samples were characterized using four point probe measurement for sheet resistance (Rsh), X-ray diffraction (XRD) for phase identification, atomic force microscopy (AFM) for surface topography, top-view and cross-sectional scanning electron microscopy (SEM) for film morphology, and 4-point bending method for quantitative adhesion evaluation. By employing a short time pre-exposure of SiH4 prior to B2H6-based ALD W, the adhesion of as-prepared W is improved significantly, which meanwhile satisfies the requirements for trench filling in real small devices. (C) 2015 Elsevier B.V. All rights reserved.