Hideaki Shimamura

Microstructure of sputter‐deposited Al–Cu–Si films

The microstructure of Al–3 wt. % Cu–1.5 wt. % Si and Al–0.5 wt. % Cu–1.0 wt. % Si films was analyzed with respect to crystal grain orientation and grain size distribution before and after annealing at 475 °C for 30 min. Films were deposited at various substrate temperatures using load‐lock magnetron sputtering systems. Crystal orientation was analyzed by Kikuchi line patterns in 20 individual grains with respect to the substrate surface in each sample. Crystal grain size distributions were analyzed in high‐Cu content films deposited under no‐heat, 140 and 280 °C predeposition conditions. θ‐CuAl2 precipitates were found in the as‐deposited 280 °C sample at the triple points of the grain boundary. This sample showed the largest orientation dispersion. This phenomenon was not affected by annealing. Stable θ‐phase precipitates formed at the grain boundaries during deposition were thought to impede the coalescence of grains resulting in a low degree of preferred orientation. Thin (0.1 μm) Al–0.5 wt. % Cu–1.0 w...

In-situ process monitoring in metal deposition processes

Process monitoring is now receiving more serious attention than ever before in an effort to increase the efficiency of equipment utilization and the stability of process quality in VLSI production lines. The objectives and effects of process monitoring are discussed in this article. The function of various process monitoring tools are also classified and examined in an effort to replace current PQC or inspection procedures. Several of the monitoring technologies developed by our research group are reviewed in detail. Stabilization of the metal deposition processes is thought to be effective in stabilizing the subsequent etching and photo processes. A sputter monitoring system in which essential process parameters are sensed in-situ is shown to be sensitive enough to detect process variations. W-CVD can be monitored by using quadruple mass spectroscopy (QMS) to provide real-time information about the onset of deposition reactions, etc. Simple time control of the deposition is not sufficient to control the process since the metal CVD reaction is susceptible to the surface state. Process tools can still be improved by the development and application of monitoring technology. However, on overall improvement in production efficiency should be attained through a good combination of process monitoring tools and a line control system.

Aluminum sputtering with intermittent pulse bias application

dc aluminum bias‐sputter deposition was studied to develop a process which better fits the requirements of very large scale integration applications such as improvements in the step coverage, control of film stress, and hillock formation. Intermittent negative bias voltage pulses were applied with a cycle period of 1 ms during the deposition of an aluminum film. The pulse has two voltage levels: Vd (deep) and Vs (shallow). The duty factor was defined as the ratio of time during which the bias voltage is Vd to the cycle period. It was found that a Vd greater than −115 V was needed to attain an appreciable improvement in the step coverage. For a duty factor of 15%, a maximum was found in the peak intensity ratio I(111)/I(200) with x‐ray diffractometry at Vd=−120 V. Minima for the film stress at room temperature and the hillock formation density after annealing at 475 °C for 30 min in nitrogen were found to occur in the bias voltage region mentioned.