Achieving conduction band-edge effective work functions by La2O3 capping of hafnium silicates

作者：Ragnarsson Lars Ake^*; Chang Vincent S; Yu Hong Yu; Cho Hag Ju; Conard Thierry; Yin Kai Min; Delabie Annelies; Swerts Johan; Schram Tom; De Gendt Stefan; Biesemans Serge

来源：IEEE Electron Device Letters, 2007, 28(6): 486-488.

DOI：10.1109/LED.2007.896900

• atomic layer deposition (ALD)
• electron mobility
• hafnium oxide
• lanthanum oxide
• MOSFETs
• sputtering
• tantalum carbide
• titanium nitride
• work function

Conduction band-edge effective work functions (Phi(m), eff) are demonstrated with TaCx and TiN by means of La2O3 capping of HfSiOx in a gate-first process flow with CMOS-compatible thermal budget. With TaCx, a 10-angstrom-thick La2O3 cap results in a Phi(m), eff of 3.9 eV with a low equivalent oxide thickness (EOT) increase (1-2 angstrom) and unaffected electron mobility. With TiN, non-nitrided La2O3 capping results in a smaller Phi(m), eff reduction at a larger EOT increase, while with post-cap nitridation, the TiN Phi(m), eff is lower at a smaller EOT increase. Results show that the choice of metal and nitridation conditions have significant effects on La2O3 capped stacks.

• 出版日期2007-6