An XRF Thin Film Growth Monitor

Statement of the Problem or Situation that is Being Addressed: Materials constructed from many ultrathin layers are increasingly used for x-ray optics in DOE laboratories and for many industrial applications. However, current tools for monitoring the growth of the film layers in situ are inadequate for the sub-angstrom measurement precision required for the newest applications. A new in situ thin film growth monitor is required. Statement of how this Problem or Situation is Being Addressed: Spectral Sciences, Inc. (SSI) proposes to demonstrate the feasibility of a thin film growth monitor based on measurements of the x-ray reflectivity of the sample as the layers are being deposited. Angle-dispersive x-ray reflectivity is a well-regarded technique for ex situ inspection of ultrathin films. SSI proposed an innovative energy-dispersive approach that requires no moving parts and may be performed in situ. What is to be Done in the Phase I: In Phase I, we will construct a bench top prototype instrument with an accurate software model of the x-ray scattering to extract the thickness of each layer from the reflectivity data. The prototype instrument will be tested using multilayer thin film samples. By bringing in situ thin film growth measurement precision in to the sub-angstrom regime, the product will enable new thin film deposition technologies essential for growth in the semiconductor and photovoltaic industries. The competitive advantages of the new tool are: Performance for ultra-thin layers, direct sample measurement in situ, low cost components, flexible, modular design. Commercial Applications and Other Benefits: Our proposed instrument is of value to a broad range of manufacturers in a variety of commercial industries as it will provide value added to their products by monitoring the production process in situ to reduce waste. The modular hardware and software design is key for customization to a range of applications. Key Words: thin film, multilayer lens, x-ray optics, x-ray reflectivity, process monitoring. Summary for Members of Congress: SSI will develop a novel tool for measurement of thin film thickness based on x-ray reflectivity of the sample. The new metrology tool will enable process monitoring of thin film deposition to sub-angstrom precision, allowing the manufacture of layered materials to higher precision than ever before.