TANAKA Kikinzoku Kogyo K.K., which operates the TANAKA Precious Metals manufacturing business, announced that TANAKA has established a two-stage film deposition process using the liquid ruthenium (Ru) precursor “TRuST.” TRuST is a precursor that shows reactivity with both oxygen and hydrogen and can form high-quality ruthenium films. This process is a two-stage atomic layer deposition (ALD) process that uses hydrogen film formation to create a thin anti-oxidation film and oxygen for the deposition of a high-quality ruthenium film. It eradicates concerns that the substrate will become oxidised and, at the same time, can prevent the drop in ruthenium purity that occurs during hydrogen film deposition.
The film deposition process was proposed by Professor Soo-Hyun Kim from the School of Materials Science and Engineering, College of Engineering, Yeungnam University in South Korea. The development and evaluation of the film deposition process were jointly conducted by Professor Kim and TANAKA Kikinzoku Kogyo.
This two-stage film deposition process reduces the risk of surface oxidation of the base caused by hydrogen film deposition and allows high-purity film deposition that maintains ruthenium purity at almost 100% using oxygen film deposition. Furthermore, by forming the base first using hydrogen film deposition, the ruthenium film on top of the base created using oxygen film deposition will be smooth and dense, achieving a lower resistance than before.
Generally, specific resistivity increases when film thickness decreases, which is an issue in film deposition of semiconductors. With this new process, it was confirmed that an even lower resistance results from a two-stage film deposition that uses hydrogen in addition to oxygen film deposition, especially in the range of 10 nm and below.