| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Tuesday Sessions |
| Session TF-TuM |
| Session: | Advanced CVD and ALD Processing, ALD Manufacturing and Spatial-ALD |
| Presenter: | Jaclyn Sprenger, University of Colorado Boulder |
| Authors: | J.K. Sprenger, University of Colorado Boulder H. Sun, University of Colorado Boulder A.S. Cavanagh, University of Colorado Boulder S.M. George, University of Colorado Boulder |
| Correspondent: | Click to Email |
Electron-enhanced atomic layer deposition (EE-ALD) can drastically reduce the temperatures required for film growth. The temperature reduction occurs because electrons can desorb surface species by electron stimulated desorption (ESD) to create very reactive “dangling bonds”. Precursors can then adsorb efficiently on the dangling bonds. EE-ALD lowers the thermal budget and enables the deposition of thin films on thermally sensitive substrates. EE-ALD has been demonstrated previously for the deposition of polycrystalline GaN [1] and amorphous Si [2] at room temperature.
BN film growth by EE-ALD was performed at room temperature on Si (111) substrates using alternating doses of borazine (B3N3H6) and low-energy electrons. Borazine is a single-source precursor for BN deposition. In situ ellipsometry was performed during the BN EE-ALD. These ellipsometry measurements yielded a linear growth rate of ~3 Å/cycle for electron energies of 100 eV with an electron current of 300 μA for 240 s. This in situ growth rate was confirmed by ex situ spectroscopic ellipsometry. A BN film with a thickness of 150 nm was deposited after ~500 EE-ALD cycles (see supplemental Figure 1). Ex situ ellipsometry measurements show flat BN thickness spatial profiles (see supplemental Figure 2) which are consistent with self-limiting reaction conditions including hydrogen desorption.
Film composition was studied with ex situ XPS (see supplemental Figure 3). The BN composition is consistent throughout the film with a B/N ratio of 1.3/1. The films are pure with C and O concentrations of only <3 at.% in the bulk of the film. A thin, self-passivating surface oxide resulting from atmospheric exposure is present. In addition, ex situ FTIR transmission was performed on the BN films. These FTIR measurements yielded an absorption peak at ~1370 cm-1 that is consistent with hexagonal BN.
[1] J.K. Sprenger, A.S. Cavanagh, H. Sun, K.J. Wahl, A. Roshko and S.M. George, “Electron Enhanced Growth of Crystalline Gallium Nitride Thin Films at Room Temperature and 100°C Using Sequential Surface Reactions”, Chem. Mater. 28, 5282 (2016).
[2] J.K. Sprenger, A.S. Cavanagh, H. Sun and S.M. George, “Electron Enhanced Atomic Layer Deposition (EE-ALD) of Silicon Films at Room Temperature”, Presentation at ALD2016 in Dublin, Ireland.