Electronic Determination of the Modulus of Elasticity and Intrinsic Stress of Thin Films using Capacitive Bridges

Abstract

We extend the method of Najafi and Suzuki [1] for the electronic determination of the modulus of elasticity and intrinsic stress of thin films using capacitive bridge structures. New theoretical concepts are introduced. The extended method does not require that the test structures be exercised to the point of snap-action.

M-TEST: A test chip for MEMS material property measurement using electrostatically actuated test structures

“…A broad array of material property extraction methods has been proposed in the literature. These methods include a resonant frequency measurement technique on cantilever beam (CB) test structures [2], [3], a direct tensile stress measurement technique [4], a capacitance/voltage (C/V) measurement technique on fixed-fixed beam (FB) bridge structures [5], the direct mechanical bending of CB test structures by a known force and measurement of the resulting deflection [6], a load/deflection technique on suspended thinfilm membranes under tensile stress and known pressure load [1], [4], [7], and an electrostatic pull-in approach using tethered rigid parallel-plate structures [8]. Most of the techniques require special micromachined structures or special test fixtures, which makes them difficult to use in routine wafer-level measurements, for example, in a manufacturing environment.…”

Characterization of contact electromechanics through capacitance-voltage measurements and simulations

“…1a) are widely used and studied in the microelectromechanical systems (MEMS) community. Such beams are used as switches [1] and resonators [2], [3], and for extracting material properties [4]- [6], [18]. One-dimensional (1D), quasi-two-dimensional (quasi-2D) and three-dimensional (3D) simulations of various accuracies and sophistication have been used to help understand and characterize these beams and devices [5]- [9].…”

Electronically probed measurements of MEMS geometries

“…In situ measurement is especially useful for monitoring material properties that can be highly process dependent [15]. Mechanical property test structures using in situ electrostatic actuation include beams and diaphragms actuated to pull-in (M-TEST) [8], [16]- [20], laterally resonant comb drives [21]- [24] and vertically resonant beams [16], [25]- [30], and capacitance-voltage measurements of fixed-fixed beam bridges [31], [32]. Nonelectrostatic methods for mechanical property measurement include load-deflection and bulge tests of membranes [33], measuring cantilever tip displacement with an externally applied force [34], and direct tensile measurement of strain [35].…”