Tailoring of crystalline phases and dielectric properties of ZrO2 thin films are demonstrated by capping a nanoscale TiN layer prepared by plasma-enhanced atomic layer deposition. The in-plane tensile strain induced by the TiN capping layer gives rise to the dramatic paraelectric-to-antiferroelectric phase transformation in ZrO2 and the significant capacitance enhancement up to 209%. The result is attributed to the formation of the ZrO2 tetragonal phase with the out-of-plane compressive strain due to TiN capping and the presence of interfacial TiO x N y , as revealed by nanobeam electron diffraction, X-ray diffraction, and X-ray photoelectron spectroscopy. The results demonstrate that the as-deposited TiN capping layer can effectively modulate the dielectric properties of nanoscale thin films without any postannealing treatment, which is very beneficial for the back-end-of-line process integration and numerous applications including supercapacitors, microelectromechanical systems, energy conversion, and nanoelectronics.

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For high-performance Ge-based transistors, one important point of focus is interfacial germanium oxide (GeOx). An AlN buffer layer effectively suppresses the interfacial GeOx, and produces a significant enhancement of the electrical characteristics.

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.

The frequency response of negative capacitance.