Stress modulation of titanium nitride thin films deposited using atomic layer deposition

Abstract

Stress engineering of thin titanium nitride (TiN) films is of considerable importance to the memory industry, where these thin films are free to deform and need to be structurally robust to the deposition of overlying films and processing steps that are a part of the fabrication flow. TiN films in the thickness range of 50 to 100 Å are deposited at 425 °C using atomic layer deposition and are tensile in nature. The as-deposited films are partially surface oxidized due to exposure to atmosphere. The films are subsequently oxidized in an ozone/oxygen ambient at temperatures lower than 275 °C to form a surface oxide layer comprising of titanium dioxide (TiO2) and titanium oxynitride (TiOxNy). Volumetric expansion associated with oxide formation is found to induce compressive stress in the film, while oxidation had the undesirable effect of increasing film resistivity. A dilute hydrofluoric acid solution is used to etch the surface TiO2 layer, while a thin TiOxNy layer remains intact on the film surface. The removal of surface TiO2 results in restoring the resistivity of the films to values comparable to that of as-deposited TiN, while maintaining the compressive stress induced by film oxidation. X-ray photoelectron spectroscopy shows that the processing scheme results in increasing the amount of TiOxNy in the near-surface region of the films. The authors postulate that the higher molar volume TiOxNy layer exerts a compressive force on the underlying TiN film, and prevents a full relaxation of the films to their original tensile stress state. Further, the authors show that by controlling the oxidation conditions, it is possible to modulate the film stress in the range of −750 to +750 MPa. The processing scheme thus allows for stress engineering of thin TiN films at processing temperatures lower than 275 °C.

Atomic layer deposition of titanium nitride for quantum circuits

“…The higher binding energy (2p 1/2 ) peaks are expected from spin-orbit coupling. Near the TiN surface, we find a thin intermediate TiO x N y transition layer [21,28]. The peak intensity of TiO 2 increases with aging, and we attribute this to a slow growth of a 5-8 nm thick oxide layer over a time scale of months.…”

“…There have been successful attempts to grow TiN films using ALD [20,21], and these superconducting films have been used to study deviations from BCS theory [22].…”

Tuning Material Properties of Oxides and Nitrides by Substrate Biasing during Plasma-Enhanced Atomic Layer Deposition on Planar and 3D Substrate Topographies

“…The film was observed to have a tensile residual stress ( Figure 11 a) similar to that reported for TiN x in previous work. 49 The XRD pattern for this film ( Figure 12 ) shows diffraction peaks that correspond to cubic TiN x . The fairly small peak intensities and broad peak widths indicate the presence of small crystal grains.…”

Spiderweb Nanomechanical Resonators via Bayesian Optimization: Inspired by Nature and Guided by Machine Learning

“…While silicon nitride is one of the most widely used thin films for nanomechanical resonators, the design approach in this work could be extended to other materials such as diamond, [68] gallium arsenide, [64,69] silicon carbide, [70,71] indium gallium phosphide, [65,72] fused silica glass, [73] silicon, [74] phosphorus carbide, [75,76] and even superconducting films. [77,78] The enhancement of mechanical quality factor results from the discovery of a soft-clamping mechanism that uses a torsional motion to isolate a nanomechanical mode from ambient thermal noise. This enables high-Q m nanomechanical resonators that have smaller aspect ratios than previous state-of-the-art designs, making them significantly easier, cheaper, and faster to manufacture.…”