Study of stress evolution of boron nitride films prepared by ion assisted deposition

The evolution of the stress during N/Ar ion assisted deposition of boron ni tride films on Si(001) substrates was measured in situ by a very sensitive capacity technique in dependence on the ion energy, temperature during depo sition, and the ion to atom arrival rate. The relative amount of c-BN in th e films was determined by Fourier-transform infrared spectrometry and the l ayered structure of these films was studied by spectroscopic ellipsometry a nd high resolution cross-section transmission electron microscopy. The stre ss evolution in dependence on the layer thickness is characterized by a hig h tensile stress in the initial stage of the film growth, followed by a tra nsition from the tensile to the compressive stress state and the saturation or weak relaxation of the compressive stress. The existence of the c-BN ph ase corresponds to a compressive stress of about 2 GPa. For a compressive s tress greater than or equal to 3.5 GPa boron nitride films with a c-BN cont ent greater than or equal to 80% were obtained. The influence of the ion en ergy, the temperature during the deposition, and the ion to atom arrival ra tio on the development of the stress is discussed. (C) 1999 American Vacuum Society. [S0734-2101(99)01802-3].