Nanocrystalline TiN has been imbedded in amorphous silicon nitride matrix to form a super hard nanocomposite thin film (nc-TiN/a-SiN x ) via magnetron sputtering. Adjusting Ti and Si 3 N 4 target power ratio altered film composition, size, amount and distribution of the nc-TiN phase. At a Ti target power density of 5.5 W cm - 2 , the Ti to Si 3 N 4 target power ratio should be greater than unity in order for nc-TiN to form, otherwise, Ti will dissolve in amorphous SiN x . The relationship between the film hardness and the crystallite size show Hall-Petch and anti-Hall-Petch relationship. A 'scratch crack propagation resistance' parameter, or CPR s =L c 1 (L c 2 -L c 1 ), has been proposed to approximate thin film toughness from the critical load data easily obtained from a scratch adhesion test.