RF-MEMS 소자의 웨이퍼 레벨 밀봉 패키징을 위한 열압축 본딩

Abstract

In this study, we describe a low-temperature wafer-level thermocompression bonding using electroplated gold seal line and bonding pads by electroplating method for RF-MEMS devices. Silicon wafers, electroplated with gold (Au), were completely bonded at 320oC for 30min at a pressure of 2.5MPa. The through-hole interconnection between the packaged devices and external terminal did not need metal filling process and was made by gold films deposited on the sidewall of the through-hole. This process was low-cost and short in duration. Helium leak rate, which is measured to evaluate the reliability of bonded wafers, was 2.740.61410-10 Pam3/s. The insertion loss of the CPW packaged was 0.069~0.085dB. The difference of the insertion loss between the unpackaged and packaged CPW was less than -0.03. These values show very good RF characteristics of the packaging. Therefore, gold thermocompression bonding can be applied to high quality hermetic wafer level packaging of RF-MEMS devices.