PURPOSE: To actuate a semiconductor element normally and stably by a method wherein a metallic substrate is effectivelly prevented from warping so as to efficiently absorb the heat generated by the semiconductor chip.

CONSTITUTION: Within the tile semiconductor element containing package, an iron alloy made frame member 2 having an insulating member 3 engaged therewith is attached to the surface outer periphery of a metallic substrate 1 so as to fixedly contain a semiconductor chip 4 in a space formed by the surface of the semiconductor chip 1 and the frame member 2 to be contained in the space. In such a constitution, the metallic substrate 1 is composed of a molybdenum plate 5 with copper plates 6, 7 junctioned with upper and lower surfaces while assuming the thickness of the molybdenum plate 5, the copper plate 6 positioned on the upper surface side whereto the semiconductor chip 4 is fixed and the other copper plate 7 positioned on the rear surface side respectively as T1, T2, T3, T2/T1 = to while T3/T2=-T2/12T1+1.3 to -T2/12T1+1.6.