Atomic Layer Deposition of Aluminum Nitride Using Tris(diethylamido)aluminum and Hydrazine or Ammonia

Aluminum Nitride Nanofilms by Atomic Layer Deposition Using Alternative Precursors Hydrazinium Chloride and Triisobutylaluminum

“…[N 2 H 5 ] + •Cl − → N 2 H 4 + HCl It is worth indicating that no presence of the latter has been detected neither by XPS nor SIMS analyses, which means HCl molecules are completely removed out of the chamber during the purge stage. It has to do with the fact the that the deposition temperature is not nearly enough to ionize HCl, hydrazine on the other hand can be activated at temperatures <250 • C [20] and, theoretically, reaction should proceed as following:…”

“…However, this minor detail should by no means be a hindrance to drawing conclusions regarding the efficiency of N2H5Cl. As will be demonstrated in the discussion section, N2H5Cl basically decomposes into hydrazine in the ALD chamber and the latter has already demonstrated positive results as a nitrogen precursor for AlN thin films [20]. Moreover, imperfections of the ALD process have then been rectified by consecutive annealing in nitrogen.…”

“…Heating of the container with hydrazinium chloride was carried out at temperature up to 90 • C (T m of N 2 H 5 Cl~89 • C). The deposition temperature of the sample batch used for analysis was 250 • C, which is within the AlN ALD window according to our GPC measurements and a plethora of other studies [2,3,6,12,13,18,20]. A part of the obtained films has been also subjected to a high-temperature annealing (1350 • C) in the nitrogen (N 2 ) atmosphere for 1 h to remove possible impurities (in particular, hydrogen impurities).…”

“…Ammonia requires high energy for activation and is reported for its limited reactivity under temperatures below 475 • C [18,19]. Hydrazine on the other hand has a more favorable thermochemistry but despite the generally positive results, the use of hydrazine (N 2 H 4 ) is associated with a number of complications, such as transportation difficulties, explosiveness, instability and expensiveness [20]. The two most common precursors nowadays for obtaining AlN seem to be Al(CH 3 ) 3 and N 2 /H 2 plasma.…”

From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides

“…Whereas, with chlorides and NH3 (or N2-H2 mixture), it is possible to deposit (Al)GaN thermally, the process occurs at high temperatures, exceeding 500 o C [113][114] . This is due to the chemical stability of the N-containing precursor (to note: reports on (Al)GaN ALD using more-reactive precursors, e.g., hydrazine, are only recently appearing 115 ). The chemical stability also limits the use of metalorganic precursors in purely thermal mode, since they dissociate at the high temperatures required to dissociate the N-containing precursor (for example, whereas NH3 starts to dissociate on the surface beyond 600 o C 116 , TMG already dissociates at ~ 150 o C 117 ).…”