Improvement of Specimen Preparation Process for Bulge Test Using the Combination of XeF2 and Deep Reactive Ion Etching

Abstract

The bulge test is a convenient approach to determine the thin film mechanical properties. This study presents a fabrication process to prepare the circular membrane made of metal as well as dielectric films for bulge test. The process successfully combines the dry etching of deep reactive ion etching (DRIE) and XeF2 to release the test metal films. The Si3N4 film is used to protect the metal layers during the release process. Thus, the ion bombardment of the test metal films by DRIE is prevented. In addition, this process is also designed to prevent the pre-deformation of the Si3N4 and the metal films before release. By changing the recipe of XeF2 etching, the circular Si3N4 test membrane can also be fabricated. In applications, the circular membranes of Al, Au, and Si3N4 films were successfully prepared using the presented approach. This study also performed the bulge test by using these specimens to determine the thin film elastic modulus.