Growth of copper metal by atomic layer deposition using copper(I) chloride, water and hydrogen as precursors

Films of copper metal have been grown on two different oxide substrate materials by atomic layer deposition. The film depositions were carried out in the temperature range 375-475 deg. C. Copper(I) chloride, water and hydrogen were used as precursors. Two deposition schemes were used and compared, one including water (CuCl/H2O/H2) and another without water (CuCl/H2). It was found that the addition of water enhanced growth rate on alumina substrates up to four times compared to the water-free deposition process. Hence, the extra water step leads to faster copper formation kinetics than from the direct reaction between CuCl and H2. On the contrary, film growth rate increased when water was excluded from the deposition process on fused silica substrates, indicating that the additional water did not lower the activation energy for the total reaction. The film growth rate was also more sensitive to changes in hydrogen pulse length and partial pressure on SiO2 substrates (i.e. hydrogen dosing). Randomly oriented polycrystalline films were obtained on amorphous SiO2, whereas on single crystalline α-Al2O3 substrates with orientations (001), (110) and (102), films showed a strong Cu(111) texture. Finally, the film morphology was rough due to island growth behaviour