Silicon oxide nanolayers for soft X-ray optics produced by plasma enhancedCVD

We have studied the suitability of Plasma Enhanced Chemical Vapor Depositio n (PECVD) to produce ultrasmooth silicon oxide layers ranging in thickness from some nanometers to some 10 nm. A tight process control of the layer th ickness, layer density and microroughness of the growing film is required. We deposited silicon oxide on silicon wafers, float glass and superpolished quartz substrates. In a remote plasma enhanced CVD process, we used tetrae thylorthosilicate (TEOS, Si(OC2H5)(4)) as precursor. Films with a thickness of some 10 nm were produced at different deposition parameters and charact erized by in-situ soft X-ray reflectivity, hard X-ray diffraction and auger electron spectroscopy. Best results could be found for the deposition usin g TEOS in oxygen plasma. In case Of SiO2 layers deposited on standard glass substrates signifcant roughness smoothing was obtained.