"The anode coupling is to bond a lower plate 3a made of a silicon wafer with an upper plate 3b made of glass such as Pyrex glass or aminosilicate glass or made of glass deposited Si by putting the lower and upper plates together, heating at about 400??? C. and applying 1000V. This bonding can integrate the lower and upper plates 3a and 3b entirely, so that hermetic sealing at side surface can be pe" . . . .