Plasma Processing for Crystallization and Densification of Atomic Layer Deposition BaTiO₃ Thin Films

Abstract

High-k, low leakage thin films are crucial components for dynamic random access memory (DRAM) capacitors with high storage density and a long storage lifetime. In this work, we demonstrate a method to increase the dielectric constant and decrease the leakage current density of atomic layer deposited BaTiO3 thin films at low process temperature (250 °C) using postdeposition remote oxygen plasma treatment. The dielectric constant increased from 51 (as-deposited) to 122 (plasma-treated), and the leakage current density decreased by 1 order of magnitude. We ascribe such improvements to the crystallization and densification of the film induced by high-energy ion bombardments on the film surface during the plasma treatment. Plasma-induced crystallization presented in this work may have an immediate impact on fabricating and manufacturing DRAM capacitors due to its simplicity and compatibility with industrial standard thin film processes.

Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

“…Previously, plasma annealing or extensions of in-cycle plasma during PEALD have shown similar improvements in thin film properties of high k oxide-based dielectrics. 11 In this paper, we report on PEALD of SiN x films with three different precursor chemistries (TSA, tris(dimethylamino)silan (3DMAS), dichrolosilane (DCS)) and the WER performance achieved with each. In particular, we note the strong correlation found between film density and WER regardless of precursor chosen, PEALD reactor utilized, or variation of several process parameters.…”

Process–property relationship in high-k ALD SrTiO3 and BaTiO3: a review

“…For example, mostly amorphous BTO with embedded crystalline moieties that provides a good tradeoff between low leakage current and high dielectric constant cannot be characterized with conventional X-ray diffraction (XRD). 64,65 In the following sections, we will review the strategies that have been developed to date for achieving high-performance perovskite thin films using ALD, particularly for STO and BTO. In addition, we will outline the characterization techniques that provide insights into the structure, composition, and dielectric properties of ALD perovskites.…”

“…Intensive research has been conducted in the area of plasma utilization for intradeposition treatment of ALD perovskite films, mostly STO films (Table 3). 64,78,[81][82][83][84][85][86][87][88][89][90][91][92][93] Kil et al showed that the oxygen remote plasma (9 s) could be used for depositing STO films using Sr(METHD) 2 (METHD = methoxyethoxy-tetramethyl-heptanedionate) even at a relatively low temperature (B250 1C) without detectable impurities (detection limit B0.1 at%). [81][82][83][84] Notably, the diketonate Sr precursor, which had been reported not to react with the most common oxygen sources, successfully reacted with remote oxygen plasma.…”

“…The use of oxygen plasma for partially crystallized STO was also reported, and the dielectric constant of the resulting STO was 65 at 50 nm. 85 showed that the crystallinity of thermally grown ALD BTO could be improved by a remote oxygen plasma treatment after deposition (i.e., post-deposition treatment); 64 the dielectric constant of the ALD BTO increased by about a factor of 2 after extensive exposure (3 hours) to remote oxygen plasma due to the partial crystallization of the BTO film surface. Prinz et al also reported the PEALD of BTO films with remote oxygen plasma.…”

“…102 Cp-type precursors have also been adopted to deposit bariumcontaining perovskites such as BTO. 64,66,93,104 For example, there is a report that BTO films were successfully deposited using barium Ba( t Bu 3 Cp) 2 with H 2 O. 66 However, even though the BTO film is deposited at a relatively high temperature (340 1C), it was amorphous, and a post-annealing process at 600 1C was needed for crystallization.…”