Journal of Electron Spectroscopy and Related Phenomena 178–179 (2010) 433–448 Contents lists available at ScienceDirect Journal of Electron Spectroscopy and Related Phenomena journal homepage: www.elsevier.com/locate/elspec XPS and angle resolved XPS, in the semiconductor industry: Characterization and metrology control of ultra-thin films C.R. Brundle a,∗ , Giuseppina Conti a,1 , Paul Mack b a C.R. Brundle and Associates, 4215 Fairway Drive, Soquel, CA 95073, USA b Thermo Fisher Scientific, The Birches Industrial Estate, Imberhorne Lane, East Grinstead, West Sussex, RH19 1UB, United Kingdom article info Article history: Available online 12 March 2010 Keywords: XPS ARXPS Semiconductor wafer Metrology Materials characterization abstract This review discusses the development of X-ray photoelectron spectroscopy, XPS, used as a characteri- zation and metrology method for ultra-thin films in the semiconductor wafer processing industry. After a brief explanation of how the relative roles of XPS and Auger electron spectroscopy, AES, have changed over the last 15 years or so in the semiconductor industry, we go into some detail as to what is implied by metrology, as opposed to characterization, for thin films in the industry, and then describe how XPS, and particularly angle resolved XPS, ARXPS, have been implemented as a metrology “tool” for thickness, chem- ical composition, and non-destructive depth profiling, of transistor gate oxide material, a key requirement in front-end processing. We take a historical approach, dealing first with the early use for SiO 2 films on Si(1 0 0), then moving to silicon oxynitride, SiO x N y in detail, and finally and briefly HfO 2 -based material, which is used today in the most advanced devices (32 nm node). © 2010 Elsevier B.V. All rights reserved. Contents 1. Introduction .......................................................................................................................................... 433 2. Characterization and metrology ..................................................................................................................... 435 2.1. Characterization .............................................................................................................................. 435 2.2. Metrology ..................................................................................................................................... 435 2.3. Precision and process tolerance .............................................................................................................. 435 3. Development of XPS for characterization and metrology of ultra-thin films ....................................................................... 436 3.1. Background ................................................................................................................................... 436 3.2. SiO 2 gate oxide film thickness as the prototype example ................................................................................... 436 3.3. SiO x N y gate oxide films ....................................................................................................................... 438 3.3.1. Background ......................................................................................................................... 438 3.3.2. Initial attempts at thickness and N dose determination for SiO x N y ............................................................... 438 4. Depth profiling by XPS in general and the determination of the N profile in SiO x N y in particular ................................................. 440 4.1. The RDP method .............................................................................................................................. 440 4.2. Modeling the ARXPS response ............................................................................................................... 441 4.3. Simultaneous thickness, N dose, and N distribution wafer metrology by ARXPS ........................................................... 447 5. Beyond SiO x N y ....................................................................................................................................... 447 6. Conclusions .......................................................................................................................................... 448 Acknowledgements .................................................................................................................................. 448 References ........................................................................................................................................... 448 ∗ Corresponding author. Tel.: +1 8314791399. E-mail address: brundle@attglobal.net (C.R. Brundle). 1 Formerly at Applied Materials, Inc., Santa Clara, CA, USA. 1. Introduction This review covers the development of XPS within the semi- conductor wafer processing industry for materials characterization and materials processing metrology. Specifically, it concentrates on the use of Angle Resolved XPS, ARXPS, for the characterization and metrology of ultra-thin films. As such, much of what is discussed 0368-2048/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.elspec.2010.03.008