Micromechanical testing of electroplated gold alloy films using theta-like specimens
- PDF / 550,472 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 68 Downloads / 207 Views
Research Letter
Micromechanical testing of electroplated gold alloy films using theta-like specimens Mark J. McLean, William A. Osborn, and Rebecca Kirkpatrick, Materials Measurement Science Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 Oliver Boomhower and Christopher Keimel, Micro and Nano Structures Technologies Group, GE Global Research, Niskayuna, New York 12309 Frank W. DelRio, Applied Chemicals and Materials Division, Material Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 Address all correspondence to Mark J. McLean at [email protected] (Received 27 March 2015; accepted 18 June 2015)
Abstract Micromechanical testing of electroplated gold alloy films has been conducted using theta-like specimens. Specimens were formed by a standard combination of photolithography, electroplating, and deep reactive ion etching. Testing was performed using an instrumented indenter and the results interpreted using a finite-element model with a Ramberg–Osgood constitutive law to extract elastic and plastic material properties. The observed results were highly repeatable and appear to be sensitive to variations in both sample dimensions and material properties. These qualities suggest that the testing methodology may have significant value as a quality control technique in the fabrication of metal microelectromechanical systems.
In recent years, the microelectromechanical system (MEMS) industry has seen an increase in the number of devices using metal films as moving components, particularly in the area of radio-frequency power handling switches.[1,2] As device performance is greatly dependent on the mechanical properties of the films used, which are, in turn, heavily dependent on their deposition parameters, there is a need for quality control (QC) techniques that can quickly and reliably detect variations in these properties. Such techniques must rely solely on fabrication processes that are compatible with, if not identical to, those used to make the actual devices. The techniques must also be relatively quick and easy to perform on a large number of samples, so that process tolerances can be accurately defined based on acceptable statistical variations. These requirements rule out any focused ion beam-dependent techniques, which are extremely common today,[3,4] as it is not feasible for such techniques to generate large enough data sets for QC applications. The requirements also rule out techniques that are reliant on complex equipment or in situ observation,[5,6] as these tests tend to be slower in both experimental setup and data analysis. In this work, we extend the application of the microscale theta test specimen to metal thin films. This specimen, introduced previously,[7] allows for a statistically significant number of samples to be tested in a time-efficient manner. This specimen geometry resembles the Greek letter Θ, and mitigates many of the gripping and alignment issues that are common with tensile
Data Loading...
