(Invited) Divide Et Impera: Towards New Frontiers with Atomic Layer Etching

Atomic layer etching (ALE) is rapidly emerging as a solution for advanced etch applications which require atomic scale fidelity /1/. In analogy to Atomic Layer Deposition (ALD), the ALE process is separated into two individual steps, one for surface modification and one for removal /2,3,4/. When these steps are saturated in time, intrinsic uniformity across the wafer and feature-to-feature as well as atomic level surface smoothness can be obtained. Separation of these steps also allows to reduce the ion energies in directional ALE which provides surface damage and selectivity benefits /4/.

Separation of complex continuous reactive ion etch (RIE) processes into simple, individual steps has profound implications. It is interesting to note the parallels to advanced mathematical algorithm development where so called “Divide and Conquer” algorithms break a complex problem into two or more sub-problems, until they can be solved and combined to give a solution to the original problem. In this talk we will discuss ALE in the context of the fundamentals of RIE, show the common roots and where ALE goes beyond RIE to allow new levels of performance and reduced complexity. The latter drives the need and opens the opportunity for better understanding of the surface reactions such as adsorption and sputtering. Latest experimental results will be shown for how dividing RIE processes into individual steps allows to conquer new heights of etch performance.

1. K.J. Kanarik, T. Lill, E. Hudson, S. Tan, S. Sriraman, J. Marks, V. Vahedi, R.A. Gottscho; J. Vac. Sci. Technol. A 33, 020802 (2015)
2. G.S. Oehrlein, D. Metzler, C. Li; ESC J. Solid State Technol. 4, N5041 (2015)
3. T. Faraz, F. Roozeboom, H.C.M. Knoops, W.M.M. Kessels; ESC J. Solid State Technol. 4, N5032 (2015)
4. S. Tan, W. Yang, K.J. Kanarik, T. Lill, V. Vahedi, J. Marks, R.A. Gottscho; ESC J. Solid State Technol. 4, N5010 (2015)