A　series　of　amorphous　Si-C-N　hard　films　were　prepared　by　an　electron　cyclotron　resonance　chemical　vapor　deposition　method.　Microstructure　characterization　revealed　that　amorphous　Si-C-N　hard　films　contained　various　bonding　states.　Among　them,　Si-　N　and　Si-　C　bonds　played　a　leading　role　in　determining　the　microstructure　of　amorphous　Si-C-N　hard　films.　Mechanical　measurements　showed　that　the　hardness　of　these　films　varied　between　17　GPa　and　28　GPa　as　a　function　of　the　tetramethylsilane　flow　rate.　A　close　relation　between　various　bonding　states　and　hardness　was　found.　The　variation　of　hardness　was　dominated　by　the　bond　fraction　that　corresponded　to　various　bonding　states.　Macroscopic　mechanical　properties　of　a　material　were　illustrated　from　the　perspective　of　microscopic　structural　characterization.　(C)　2014　Elsevier　B.V.　All　rights　reserved.