Non-destructive electrical test detection on copper wire micro-crack weld defect in semiconductor device

Abstract

Structural integrity of wire bonding interconnection is having a significant impact on the quality of microelectronic devices. Conventional electrical test methodology is unable to detect 10 to 20 μm of cracks that exists in wire bond stitch weld (wedge bond) in semiconductor device. This type of crack is termed as micro-crack and it becomes prominent in Power MOSFET Molded Leadless Package. If the imperfect bonded electronic package does not screen out, it may create a potential interconnection failure during product lifetime. Typical industrial based testing method was unable to identify and isolate the failure packages. Therefore, this was the aim of this research to investigate another methodology [Time Domain Reflectometry (TDR)] for this purpose. In order to complement with the TDR results, other non-destructive [3D X-ray Computed Tomography (CT) inspection] and destructive [Scanning Electron Microscope (SEM)] test techniques were used. Novelty of this work is the non-destructive electrical test methodology that able to detect micro-crack defect at wedge bond in a Power MOSFET gate wire. This test methodology offers the short test time and provides high accuracy and efficiency test result. TDR has overcome the conventional test limitation and achieved a novel approach through the defined detection resolution for micro-crack weld.