Improvement of the cantilever beam technique for stress measurement during the physical vapor deposition process

Abstract

An improvement of an optical method for in situ measurement of the intrinsic stress in thin films is described. The method presented is based on the well-known beam bending technique using the deflection of a laser beam that reflects itself on a sample. The first new development lies in the evaluation of the bending plate equation. The second uses image processing to determine the deformation of the sample. The method has been applied to pure chromium films on glass substrates to validate the stress measurements. The reproducibility of stress measurement is of about 8%. Results show the great adaptability of the technique to any kind of stress evolution during the physical vapor deposition process and give additional information about the evolution of stress versus film thickness, in comparison with ex situ techniques. Finally, a correlation between stress measurement and microstructure has been carried out.

In Situ Stress Measurement Techniques on Li-ion Battery Electrodes: A Review

“…Curvature measurements (basics and applications of the LBPD [23][24][25][26][27][28][29] and basics and applications of the MOSS [30][31][32][33][34][35][36][37][38])…”

“…However, the deflection angle can be measured only if an incident beam strikes on the free terminal of a cantilever in Equation (2). Assuming that the deflection is much smaller than the cantilever length, Moulard et al [25] provided a simple solution to the curvature at any position of a cantilever. The schematic used to calculate the curvature of a cantilever is shown in Figure 2b.…”

“…where D denotes the distance between points A and E, and d denotes the distance between points B and F. Block diagram of in situ stress measurements for a film object: (a) a thin-film electrode [24]; and (b) a cantilever [25].…”

“…During electrochemical cycling, Pyun et al [28] observed the Figure 2. Block diagram of in situ stress measurements for a film object: (a) a thin-film electrode [24]; and (b) a cantilever [25].…”

Calibrating laser beam deflection systems for use in atomic force microscopes and cantilever sensors

“…For example, there have been several papers that addressed the noise and resolution limits of the beam deflection system, [3][4][5] while others have sought to develop a means to obtain a relationship between the cantilever deflection and the signal measured from a position-sensitive detector ͑PSD͒. [6][7][8][9][10][11] Among these, it is generally accepted that for small deflections, the detector signal is directly proportional to the cantilever deflection. Some authors have proposed that the constant of proportionality is a function only of the cantilever length ͑CL͒ and the cantilever/PSD separation ͑L͒.…”