High-throughput characterization of stresses in thin film materials libraries using Si cantilever array wafers and digital holographic microscopy

Abstract

We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic microscope (DHM) is employed to simultaneously monitor the thin film thickness, the surface topography and the curvature of each of the cantilevers before and after deposition. The variation in stress state across the thin film materials library is then calculated by Stoney's equation based on the obtained radii of curvature of the cantilevers and film thicknesses. DHM with nanometer-scale out-of-plane resolution allows stress measurements in a wide range, at least from several MPa to several GPa. By using an automatic x-y translation stage, the local stresses within a 4-inch materials library are mapped with high accuracy within 10 min. The speed of measurement is greatly improved compared with the prior laser scanning approach that needs more than an hour of measuring time. A high-throughput stress measurement of an as-deposited Fe-Pd-W materials library was evaluated for demonstration. The fast characterization method is expected to accelerate the development of (functional) thin films, e.g., (magnetic) shape memory materials, whose functionality is greatly stress dependent.

Influence of residual stress on the adhesion and surface morphology of PECVD-coated polypropylene

“…The stress sensors [28] for measuring the residual stress σ res are fabricated using 4 inch (1 0 0) Si wafers (Si (1 0 0) wafer with a thickness of 525 µm, 0.3 µm thermal oxide (SiO 2 ) and a 0.1 µm low-pressure chemical vapour deposition nitride (Si 3 N 4 ) layer on top) by MEMS technologies. The complete fabrication process of the stress sensors is described in detail elsewhere [29]. The thickness of the cantilevers is t s = 26 µm and the width of each cantilever is w = 400 µm.…”

Applications of high throughput (combinatorial) methodologies to electronic, magnetic, optical, and energy-related materials

“…108 Indeed, cantilever arrays have served as a versatile combinatorial platform for mapping a variety of mechanical properties such as film stresses, glass transitions, and fatigue. 311,[423][424][425][426] Finally, other dense MEMS sensor arrays, such as microhotplates for nanocalorimetry and gas sensors, have been very useful in high throughput measurements. [427][428][429] Figure 82 illustrates a nanocalorimeter array device.…”