The purpose of the present invention is to densify an interlayer insulating film (10) by performing H2 anneal. When the densification is performed, compared with when the densification is not performed, the interlayer insulating film (10) becomes hardened. Accordingly, when a heating step involving an elevated temperature is performed after contact holes (10a, 10b) are formed in the interlayer insulating film (10), rounding of the corners of side walls of the contact holes (10a, 10b) is suppressed. Thus, even if an Al-Si layer (9d, 31c) forming a metal electrode is embedded in the contact holes (10a, 10b) by a large amount, deformation of the interlayer insulating film (10) due to stress is suppressed, and cracking in a gate insulating film (7) due to the stress is suppressed.