Saturday, January 11, 2020

A comparasion of Hafnium and Zirconium ALD precursor comparison

Here is a very nice review paper from Uwe Schröder and co-workers at NaMLab in Dresden on comparing Hafnium and Zirconium ALD precursors published in the past decades and the selection for mixed HfO2 and ZrO2 ALD high-k and ferroelectric applications.

HfxZr1 − xO2 thin films for semiconductor applications: An Hf- and Zr-ALD precursor comparison editors-pick

Journal of Vacuum Science & Technology A 38, 022402 (2020);
Monica Materano, Claudia Richter, Thomas Mikolajick, and Uwe Schroeder
In the last few years, hafnium oxide (HfO2), zirconium oxide (ZrO2), and their intermixed system (HfxZr1 − xO2) have aroused more and more interest due to their outstanding properties in the frame of semiconductor applications. Different mixtures of these two sister materials, i.e., different Hf:Zr ratios in HfxZr1 − xO2 layers, as well as different crystal arrangements come with a wide set of structural and electrical properties, making this system extremely versatile. Starting from an amorphous layer, the different crystalline phases are easier to be targeted through subsequent thermal treatment. A correct understanding of the deposition process could help in obtaining films showing the addressed material properties for the selected application. In this paper, a comparison of Hf- and Zr-atomic layer deposition precursors is conducted, with the goal of depositing an almost amorphous HfxZr1 − xO2 layer. Material composition is tuned experimentally in order to address the properties that are relevant for the semiconductor industry. The observed trends are examined, and guidelines for applications are suggested. 

Growth per cycle for the most common HfO2 metal precursors as a function of deposition temperature. Except for the Hf[N(CH3)(C2H5)]4 precursor used in this work, the data have been extracted from other sources. (Reference for HfI4-O2 is wrong, should read ref. 28.)

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