PURPOSE: To obtain a semiconductor device mounting ceramic substrate which joins a low temperature burning multilayer substrate on an aluminum nitride substrate and excels in heat dissipation and high frequency properties and attains a high degree of density.
CONSTITUTION: A junction layer 14 is adapted to be present between a low temperature burning multilayer substrate 13 and aluminum nitride 12. This junction layer 14 joins both substrates firmly. A surface processing layer 12A is formed on the surface of the aluminum nitride substrate 12 on the junction side, thereby reinforcing the junction. The low temperature burning multilayer substrate 13 is laminated with a plurality of green sheets and then burnt by heating and formed before it is connected with the aluminum nitride substrate 12 by means of the junction layer 14. This construction makes it possible to avoid the junction failure with the aluminum nitride substrate 12 resulting from the shrinkage of the green sheets.
YOSHIDA HIDEAKI
KUROMITSU YOSHIO
