Die Partialdrücke gasförmiger Spezies, die sich im Gleichgewicht mit festem Si im System Si‐H‐Cl befinden, werden als Funktion der Temperatur bei verschiedenen Cl/H‐Verhältnissen und Gesamtdrücken behandelt.

The publication costs o~ this article l~ave been assisted by the Dow C o m i n g Corporation.At present quartz is the most important material for producing tubes and boats for diffusion and oxidation processes in silicon device technology. The advantage of quartz compared to other materials is its combination of purity, resistance to mechanical and temperature changes at high temperature, and good workability. But there are limits for the application of quartz. At temperatures exceeding 1200~ it becomes increasingly soft and devitrifies, especially where it contacts other materials. In this state, quartz tubes slowly sag and flatten, and also become more permeable to gases and trace impurities. High ter~peratures are, however, necessary to accelerate the different diffusion and oxidation processes.Quartz can be obtained in a relatively pure quality. However, even these pure grades contain undesirably high levels of some metal impurities such as sodium, which must be excluded from various oxidation processes.One of the most disturbing effects in silicon device processing is the generation of clusters of dislocations at contact points between the quartz boat and a silicon wafer during high temperature processing, partly caused by mechanical stress at these points of the wafer. This phenomenon is shown in Fig. 1 by a wafer that had been dislocation-free before processing. The mechanical stress that produced these dislocations was due to the difference in thermal expansion coefficients between the silicon wafers and the quartz boat.The use of silicon tubes prepared by chemical vapor deposition (CVD) eliminates most of the difficulties encountered with quartz tubes. Polycrystalline silicon does not soften like quartz at temperatures approaching 1400~ its resistance to cracking caused by thermal shock is excellent; its purity level is very high; and its coefficient of expansion is nearly identical with that of the silicon wafers.Si-tubes and boats can also be made from monocrystalline or polycrystalline bulk silicon by coring, sawing, and grinding methods. This is, however, an expensive and difficult process due to the somewhat brittle material. Preparation of Silicon TubesPolycrystalline silicon tubes and other shaped hollow bodies are produced by the same basic CVD method used to deposit semiconductor-grade silicon rods: the hydrogen reduction of pure trichlorosilane. In the case of hollow bodies, however, it is necessary * Electrochemical Society Active M e m b e r . K e y w o r d s : s e m i c o n d u c t o r t u b e s a n d boats, silicon tubes and boats, quartz tubes and boats, vapor d e p o s i t i o n , t r i c h l o r o s i l a n e reduction, silicon deposition.Fig. 1. Clusters of dislocations generated on a silicon wafer at its two contact points with a quartz boat used during processing.to deposit silicon on a substrate such as pure graphite (1,2), the outside dimensions of which become the inside dimensions of the silicon form being grown. The over-all chemical reaction taking place at temperatures exceedin...

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T h e g o a l o f t h i s p r o g r a m i s t o d e m o n s t r a t e t h a t a d i c h l o r o s i l a n e-b a s e d r e d u c t i v e c h e m i c a l v a p o r d e p o s i t i o n (CVD)

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