Bonding of IC bare chips for microsystems using Ar atom bombardment

Abstract

This paper describes integrated circuit (IC) bare chip bonding tomicromechanical devices and discusses factors affecting bond and IC qualities.Test element group (TEG) with protective diode and TEG with transistors, small-scalecircuits and junctions were used here as the IC chips. Some of the TEGdies were thinned into films. In the bonding process, an Ar atom beam is usedto sputter clean the surface to be bonded. After contaminants on the surfacesto be bonded are removed by the Ar atomic beam irradiation, the IC chip, a dieor a film is bonded to a silicon substrate. The IC dies and the films can bebonded at low temperature and under low pressure. The strengths of the joints aregood enough for use in microsystems. There is no difference in current-voltage propertiesof the IC films before and after the irradiation. The shapes of the ring osillatorwaves of the bonded IC films are not distorted by the thermal tests. Thissuggests that the thermal tests do not cause electrical damage to the ICchips. Although the joints of IC film/Si substrate have a few fine voids at theinterface, the thermal conductivities of the joints are compared to those ofIC films before bonding. The results given show the feasibility ofmounting bare IC chips onto substrates of microsystems.