Chemical Vapor Deposition of Silicon Dioxide Films

The use of chemical vapor deposition for various insulator films is paramount in the fabrication o f semiconductor devices. The initial use of such films for passivation led to the development of low temperature techniques for film deposition. With the availability o f silane, the pyroly­ sis of silane in the presence of oxygen at atmospheric pressure provided the deposition mechanism. Further enhancements in film characteristics through the use o f phosphorus as a dopant within the film allowed the film to provide gettering of impurities during wafer fabrication. This led to the need for “smoothing” the films, now known as reflow, to minimize the sharp comers that metal lines had to cover. Reflow was further enhanced by the addition o f boron as the dopant. This technology continues to be used today with better implementation o f the reflow processes.