PURPOSE: To increase thermal dissipation and to increase the mounting density, by making air-tight sealing for the semiconductor element having PN junction, in the package using silicon as the package material and taking the silicon as the base.

CONSTITUTION: On the package 2 consisting of silicon, Au-Si eutectic alloy layer 3 is passed thru the LSI chip 1, and the insulation film 4 of silicon oxide or silicon nitride is coated on the main body 2 by surrounding it. Next, on the film 4, the conductive wiring 5 is made and bonding is made by using the chip 1 and the gold fine wire 6, and the wiring 5 is bonded with the external lead terminal 7 with solder 8. After that, the fixing material 10 is used for the upper part such as low melting point glass, and similarly, the package cover 9 of silicon is covered and air tight seal is made. Thus, the silicon excellent by 5 times for the thermal conductivity in comparsion with aluminum convertionally used is used and the heat dissipation can be increased