Electron-Enhanced Deposition of Titanium-, Silicon- and Tungsten-Containing Films at Low Temperatures Using Volatile Precursors with Various Reactive Background Gases

Electron-enhanced atomic layer deposition (EE-ALD) and electron-enhanced chemical vapor deposition (EE-CVD) can be employed for the low temperature deposition of thin films using volatile precursors with various reactive background gases (RBGs). EE-CVD expands on the previous demonstration of TiN EE-ALD using alternating Ti(N(CH 3 ) 2 ) 4 (tetrakisdimethylamino titanium (TDMAT)) and electron beam exposures with NH 3 RBG. During EE-CVD, the electron beam and the RBG are present continuously. Together with the RBG and electron beam incident on the surface, the volatile precursor is pulsed into the vacuum chamber to control the film growth. In this survey, the metal or metalloid precursors were TDMAT, Si 2 H 6, and W(CO) 6 . The RBGs were O 2, NH 3, CH 4, and H 2 . The study focused on TiO 2 EE-ALD and SiN, SiO 2, SiC x, SiH x, W 2 N, WO x, and WC x EE-CVD. Thin film growth was monitored using in situ 4-wavelength ellipsometry. To first illustrate EE-ALD, TiO 2 EE-ALD was performed at T < 80 °C using alternating TDMAT and electron beam exposures together with O 2 RBG. The growth rate for the TiO 2 EE-ALD was ∼0.7 Å/cycle. The TiO 2 EE-ALD films were nearly stoichiometric, displayed crystallinity, and were smooth as measured by atomic force microscopy (AFM). Other Ti-containing EE-ALD films were deposited using CH 4 and H 2 RBGs. Subsequently, to demonstrate EE-CVD, SiC x EE-CVD was performed at T < 100 °C using repeating Si 2 H 6 pulses with continuous electron beam and CH 4 RBG exposures. XPS revealed a 1:1 Si/C stoichiometry for a CH 4 RBG pressure of 0.45 mTorr and C-rich films for higher CH 4 RBG pressures. The SiC EE-CVD growth rate was ∼0.4 Å per Si 2 H 6 pulse. The stoichiometric SiC EE-CVD films were smooth as measured by AFM. Other Si-containing EE-CVD films that were deposited included SiO 2, SiN and SiH x . In addition, W 2 N was deposited with EE-CVD at T < 120 °C using repeating W(CO) 6 pulses with continuous electron beam and NH 3 RBG exposures. The W 2 N EE-CVD growth rate was ∼0.17 Å per W(CO) 6 pulse. The W 2 N films had a resistivity of ∼450 μΩ cm. The W 2 N EE-CVD films also displayed crystallinity and high purity. Other W-containing EE-CVD films that were deposited included WO x and WC x . This survey shows that the EE-ALD technique can be extended to EE-CVD with various RBGs to deposit a broad range of materials at low temperatures including oxides, nitrides and carbides.