Wire bonding, a process of the connection between a semiconductor chip and a lead frame by a thin metal wire, is one of the important processes of electronic packaging. This paper presents failure estimation of a silicon chip and a GaAS chip during a gold wire bonding process. The gold wire bonding process is carried out by pressing a gold ball made at a tip of the gold wire on a semiconductor chip and vibrating it by ultrasonic. High contact pressure is useful for shortening the process cycle, but it sometimes causes failure of the semiconductor chip. Elastic-plastic large deformation contact analyses are performed and the distributions of the stresses in these semiconductor chips are investigated. The possibility of failure of a semiconductor chip under usual wire bonding pressure is pointed out only for a GaAs chip.

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The effects of gas species on the charge build-up in reactive ion etching (RIE) have been investigated. The charge build-up was evaluated using metal/nitride/oxide/silicon (MNOS) capacitors and metal/oxide/silicon (MOS) capacitors. It was found that etching with electronegative gases such as O2 and CF4 results in considerable charge build-up. The spatial distribution of plasma parameters was diagnosed using a Langmuir probe. It was found that the spatial distribution of plasma parameters is non-uniform in plasmas of negative gases,while it is uniform in H2, He, Ar, and Xe gas plasmas. The results suggest that we must take the effect of the gas species into consideration for the nonuniformity in a plasma, which causes the significant charge build-up. Models that can be used to explain the effect of gas species are discussed. It was also found that the charge build-up can be drastically reduced by adding H2 gas to negative gases.

We found that self-alignment accuracy was better than ±2 μm in the case with an initial offset of up to 1 mm. This method, driven by the surface tension force of the liquid, offers new technical solutions for both high accuracy chip bonding and low cost placement manner. Some important points, such as wetting behaviour, die release offset, and the influence of defects on a die, were studied in order to suggest approaches to robustness in this new technique.