Hot-glass sealed silicon diodes

A hard-glass kovar encapsulation technique for hermetically sealing diffused silicon mesa diodes is described. The seal-in operation is a hot-seal technique, since the glass parts of the package reach temperatures from 800°C to 1000°C during the final sealing operation, and the silicon wafer is exposed to high temperatures during closure of the package. Experiments with this structure indicate that this hot-seal process leads to a relatively clean, dry environment and a stable semiconductor surface. Electrical characteristics of silicon wafers are preserved or improved by hot seal-in, and the encapsulated diodes exhibit a high degree of electrical stability.