Aluminum Patterned Electroplating from AlCl₃–[EMIm]Cl Ionic Liquid towards Microsystems Application

Abstract

Electroplating process is being used to deposit a relatively thick film of metallic materials for various microsystems applications, such as for the wafer-level bonding sealing frame and as a thermal actuator. Recently, the Al electroplating process from ionic liquid has been an attractive deposition method for anti-corrosion coatings. To extend the utilization of the film, in particular for microsystems application, a microstructure formation by patterned electroplating of Al from AlCl 3 ⁻1-ethyl-3-methylimidazolium chloride ((EMIm)Cl) ionic liquid is investigated in this study. The influences of each deposition parameters to the electroplating process as well as the resulting surface morphology are evaluated. Electroplated Al deposits on both Au and Al seed layers are both studied. It is also found that a recurrent galvanic pulse plating process yields in a higher current efficiency. Finally, Al electroplating on a 2 µm-trenched 100 mm-wafer is also demonstrated.

Keywords

• aluminum
• electro-chemical deposition
• ionic liquid
• recurrent galvanic pulse
• patterned deposition
• EMIC