UC San Diego
Passivation for Selective ALD and CVD of Metals, Metal Oxides, and Metal Silicides.
- Author(s): Anurag, Ashay
- Advisor(s): Kummel, Andrew C
- et al.
As the scaling of nanoelectronic features continues well below the 5 nm node, conventional patterning mechanism like lithography and etching are unable to create aligned features with low margin errors and low line edge roughness. Atomic layer deposition (ALD) and chemical vapor deposition (CVD) help overcome this challenge. However, ALD typically leads to conformal deposition over the entire surface, without any control on the lateral arrangement of the atoms .Self-assembled monolayers (SAMs) can be used to locally deactivate the ALD growth if they can be selectively deposited. A critical issue with SAMS is that they are typically applied by using wet chemistry and are composed of long chain molecules (1-2nm) which require long deposition times to get molecular alignment which is needed for effective passivation.
This work reports effective vapor phase passivants for the application of self-assembled monolayers of small molecules to deactivate the selected ALD growth area. The passivants used are smaller than 1nm in length, create a film with RMS roughness of less than 5 Angstrom, and require low processing temperatures. Using one such passivant, [tetramethyldisilazane (TMDS)], up to 12nm of HfOx was deposited on Si without any deposition on passivated SiCOH and SiO2. Deposition of metals like cobalt was also investigated by ALD. Contact angle was used to characterize the hydrophobicity of the surface, the surface topology was examined by atomic force microscopy (AFM) and the metal/metal oxide growth was characterized by x-ray photoelectron spectroscopy (XPS).