Back end of the line

Due to great benefits including excellent conformality and thickness controllability at atomic scale, atomic layer deposition (ALD) is being considered as a promising deposition technique, for sub-20 nm technology node logic device fabrication. Among various potential applications in logic device fabrication, the ability of ALD to deposit various metal and nitride films with high quality at low temperature makes it a viable deposition process for back end of the line (BEOL) process. First, transition metal deposition technique with extremely good conformality is required for silicide contact formation with low contact resistance. On top of the silicide contact, tungsten plug formation with very good gap filling property is required. Also, for Cu metallization, very thin and conformal deposition of diffusion barrier and seed layer is essential for good gap fill by electroplating. In this chapter, we will review the efforts on the application of ALD at BEOL process; including contact/plug formation and metallization.