Eisuke Nishitani

Excimer laser initiated chemical vapor deposition of tungsten films on silicon dioxide

Photochemical vapor deposition technique using an ArF excimer laser has been employed to deposit W films on SiO2 and Si from a WF6 and H2 system. Adhesion characteristics of the film to SiO2 are found to depend both on substrate temperature and on H2/WF6 gas flow ratio: good adhesion is obtained with an increase in the temperature or the ratio. Film formation has reaction orders of 1, 1/2 , and 1 with respect to deposition time, and WF6 and H2 partial pressures, respectively. An activation energy of 0.36 eV is estimated for this film formation on both SiO2 and Si; this energy is plausibly due to H atom diffusion on the W surface. These findings are different from conventional thermal chemical vapor deposition. Film resistivities as low as about 2× the value of bulk W have been observed in the substrate temperature range 250–500 °C. The crystalline structure of the film deposited in this temperature range is uniquely of the α phase. The crystal orientation of the film depends both on substrate temperature ...

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.