Evaluation of Low Temperature Silicon Nitride Spacer for High-k Metal Gate Integration

As transistor dimension becomes smaller and with the switch to high-k metal gate (HKMG) integration, the need for a sidewall protection layer that is conformal yet meets the low thermal budget requirement becomes critical. In this work, we evaluated PEALD SiN as spacer material in comparison to PECVD SiN, at two different stresses (compressive and tensile) and two different deposition temperatures. Material characterization reveals that PEALD SiN has lower hydrogen impurities, higher density and better resistance against wet chemistry, indicating superior material quality. In addition, film conformality and pattern density characteristics for all PEALD SiN films are significantly improved over PECVD SiN. These improvements in film characteristics help drive improvement in electrical properties for devices with PEALD SiN spacer. (C) 2013 The Electrochemical Society. All rights reserved.