In situ infrared spectroscopic study of cubicboron nitride thin film delamination

This paper investigates the procedure of cubic boron nitride (cBN) thin film delamination by Fourier-transform infrared (IR) spectroscopy. It finds that the apparent IR absorption peak area near 1380\,cm$^{-1}$ and 1073\,cm$^{-1}$ attributed to the B--N stretching vibration of sp$^{2}$-bonded BN and the transverse optical phonon of cBN, respectively, increased up to 195{\%} and 175{\%} of the original peak area after film delamination induced compressive stress relaxation. The increase of IR absorption of sp$^{2}$-bonded BN is found to be non-linear and hysteretic to film delamination, which suggests that the relaxation of the turbostratic BN (tBN) layer from the compressed condition is also hysteretic to film delamination. Moreover, cross-sectional transmission electron microscopic observations revealed that cBN film delamination is possible from near the aBN(amorphous BN)/tBN interface at least for films prepared by plasma-enhanced chemical vapour deposition.