Influences of substrate bias on the composition and structure of carbon nitride thin films prepared by ECR-plasma assisted pulsed laser deposition

摘要

The influences of substrate bias on the properties of carbon nitride thin films, prepared by plasma assisted ulsed laser deposition, are reported. We demonstrated the feasibility of preparation of carbon nitride thin films containing high nitrogen content. A reactive nitrogen plasma was provided by electron cyclotron resonance (ECR) microwave discharge in nitrogen gas. Target ablation and film preparation were performed in the nitrogen plasma environment, with the growing films being concurrently bombarded by the low-energy nitrogen plasma stream. Rutherford vbackscattering spectroscopy, X-ray photoelectron spectroscopy. Fdourier transform infrared spectroscopy and Raman spectroscopy were used for composition determination and structure analysis. Films consisting homogeneously of carbon and nitrogen were obtained on Si (1 0 0) substrates at low temperatures (<80 deg C), with nitrogen content over 50 at.% depending on the bias voltage applied to the substrates. Structural analysis reveals that nitrogen and carbon in the films are bonded through hybridized sp~2 and sp~3 configurations and the prepared films can be considered as a compound containing amorphous carbon phase, N-bonded sp~2 configurations and the prepared films can be considered as a compound contining amorphous carbon phase, N-bonded sp~2 and sp~3 configurations and the prepared films can be considered as a comound containing amorphous carbon phase, N-bonded sp~2 and sp~3 hybridized carbon. Besides the composition dependence on the substrate bias voltage, strong influences of the bias voltage on deposition rate and bonding configuration dependence on the substrate bias voltage, strong influences of the bias voltage on deposition rate and bonding configuration was also observed. The large amount of highly activated nitrogen species created by ECR discharge is expected to be responsible for efficient nitrogen incorporation, bonding formation and film growth. The subsequent surface reactions promoted by the energetic active plasma stream with higher energies ws observed to decrease nitrogen content and deposition rate due to re-sputtering effect.