Low-Temperature Conformal Atomic Layer Etching of Si with a Damage-Free Surface for Next-Generation Atomic-Scale Electronics

Abstract

Conformal atomic layer etching (cALE) of Si is realized on the basis of layer-by-layer self-limiting deposition and self-stop etching processes at low temperatures. In each cALE cycle, a conformal oxide layer was prepared by atomic layer deposition (ALD) on Si, resulting in the formation of an ultrathin SiOx interfacial layer between the oxide and Si. Afterward, the oxide and interfacial layers are removed by self-stop wet chemical etching, leading to the cALE of Si. The etching depth exhibits high linearity with respect to the applied cALE cycles, revealing a precise etching rate of a few angstroms per cALE cycle. The AFM measurement shows a low surface roughness after the cALE process as compared with other etching methods. Moreover, the evidence of conformal etching of cALE is provided by the TEM images of fin/trench structures. Also, the high-resolution TEM image demonstrates a smooth and damage-free Si surface after the cALE process. This layer-by-layer, conformal, self-limiting, self-stop, and damage-free cALE technique is highly beneficial to advanced semiconductor fabrication technology for next-generation atomic-scale electronics.

Study on Mechanisms of Photon-Induced Material Removal on Silicon at Atomic and Close-to-Atomic Scale

“…However, ALD is generally applied to large-area deposition and is difficult to use in the fabrication of ACS features. Similar to ALD, thermal atomic layer etching (ALE) [12,13] and plasma-assisted ALE [14][15][16][17][18] were proposed to remove silicon atoms layer by layer, in which heat or plasma was used to remove the atoms modified by precursors. Nevertheless, the spatial distributions of temperature and plasma energy are difficult to control with high precision.…”