Low pressure CVD boro-hydro-nitride films and the application for X-ray mask

Films containing boron, nitrogen and hydrogen have been deposited at 388–700°C by reacting diborane and amronia at reduced pressure. The deposition rate is 100–200 A /min at 400°C. The refractive index is 1.9–2.0 at 400°C. All films deposited at several temperature have strong B–N absorption from 1310 to 1400 cm−1. The films are composed of B1–3NH and are noncrystly. The measured resistivity is about 5*10E7Ωcm. The wafer bow method is used to measure the stress of the films. The stress of the films can be controlled in the range of (1–5)*10E8 dynes/cm² by the vacuum annealing after the deposition at 400° C. The optical transmission of the film was measured in the range of wavelength fron 200 to 800 nm. It is about 70% at 600 nm. The film is chemical inertness but it can be etched quickly by (C7F14 + 02) plasma. We have fabricated BN X–ray mask with vertical wall submicron gold absorber patterns which are obtained by RIE and DC electroplating technique. It will be used for synchrotron X–ray exposures at BEPC in China.