Electrical, Mechanical, and Hermeticity Properties of Low-Temperature, Plasma Activated Direct Silicon Bonded Joints

Abstract

The electrical, mechanical, and hermeticity properties of low-temperature, plasma activated direct silicon bonds were investigated. On individual dies with a bonding area ranging from 1 – 4 mm2, the bonded interface was found to have a capacitance ranging from 2.62 pF/mm2 – 2.89 pF/mm2 at 1 kHz. Linear I-V curves showing ohmic behavior without hysteresis and a resistance around 2.2 W were measured at DC voltage. We speculate that the capacitive and resistive responses are related to traps that are formed during the plasma activation process. The applied bonding process resulted in hermetic sealing with 100% yield on 2 × 481 dies. The maximum leak rate of the seals was 3.5 × 10-11 mbar×l×s-1, but could be significantly lower. No gross leaks were observed following a steady-state life test, a thermal shock test, and a moisture resistance test applied on 100 dies.

(Invited) Plasma Processes for Emerging Silicon-Based MEMS, NEMS and Packaging Applications

“…Plasma processes are critical in enabling reproducible dry deposition and etch steps during the manufacturing flow of MEMS and NEMS devices. Increasingly they are also being adopted in nano-imprint lithography (3) and bonding process steps (4)(5)(6). Plasma processes may be divided into the following broad families:…”