A silicon nitride sintered body having low hardness and semiconductor manufacturing parts for using

PROBLEM TO BE SOLVED : To provide a silicon nitride sintered compact having low hardness of a degree, at which silicon is not damaged, to use for parts of various semiconductors such as a susceptor, a chuck, a ring or a dummy wafer, the producing method and the parts for producing the semiconductor. SOLUTION : The silicon nitride sintered compact is composed of a silicon nitride crystal phase, a rare earth element, silicon aluminum, oxygen and nitrogen, contains 50-75 wt.% silicon nitride, 25-50 wt.% in total of the quantity of the rare earth element expressed in terms of oxide, the quantity of aluminum expressed in terms of oxide and the quantity of oxygen as an impurity expressed in terms of SiO2 and has 8-12 GPa Vickers hardness and <=5% porosity. The silicon nitride sintered compact is used as the part for producing the semiconductor.