Process Development of Volatile Cobalt ALD Precursors
Cobalt thin-films have found widespread applications in microelectronics devices; such as liners in copper interconnects, wetting layers, and caps, in addition to applications for magnetic devices and CoSi2 contacts. CVD and ALD techniques are typically used to achieve cobalt films between 2-5 nm thick with excellent conformalities and negligible resistance increase. Leading precursors for cobalt thin-film deposition include cyclopentadienylcobalt dicarbonyl and dicobalt(hexacarbonyl)tert-butylacetylene. While methods to prepare these precursors are well established, their scalability and/or process robustness for metric ton manufacturing remains unclear. Moreover, their stability profiles are not well understood, and data describing their decomposition is fleeting. In order to support optimum CVD/ALD precursor delivery temperatures, extended thermal stability of precursors is important. This project aims to develop scalable manufacturing processes to produce cyclopentadienylcobalt dicarbonyl and dicobalt(hexacarbonyl)tert-butylacetylene, and seek to understand their thermal stabilities in both the liquid- and gas-phase, by probing their decomposition points and identifying their decomposition products.