(400h) Electrochemical Atomic Layer Deposition and Etching of Metals for Applications in Semiconductor Nano-Manufacturing

With continued miniaturization of semiconductor devices following Moore’s law, the industry critically needs technologies for atomically precise deposition and etching of materials. Conventional vapor-phase or plasma-assisted techniques of atomic layer deposition (ALD) and etching (ALE) provide the requisite atomistic control; however, these processes suffer from low rates, often use unstable precursors and may introduce undesirable surface contamination. An alternative approach which utilizes benign liquid-phase precursors and theory-guided electrode potential manipulation, termed “electrochemical ALD” has been developed in our laboratory. In our electrochemical ALD approach, a sacrificial monolayer of zinc (Zn) is deposited on the
substrate (e.g., Cu) via underpotential deposition (UPD). The Zn adlayer then undergoes spontaneous surface-limited redox replacement (SLRR) by a nobler metal such as Cu or Co. The sequence of UPD followed by SLRR provides multi-layered metal deposits fabricated essentially one atomic layer at a time. An analogous approach for electrochemical ALE is also under development in our laboratory. In the latter approach, surface-limited oxidation of Cu followed by selective etching of the surface oxidized layer in acid provides etching of bulk metal films one atomic layer at a time. This talk will outline the fundamental characteristics of aforementioned electrochemical ALD and ALE processes, and will highlight the advantages of these processes over traditional embodiments of ALD and ALE.