FTIR reflectance characterization of SIMOX buried oxide layers

摘要

The technique of implanting silicon wafers with sufficient oxygen to form a continuous buried oxide (BOX) layer is known as SIMOX (Separation by Implanting Oxygen). SIMOX wafers present leading-edge semiconductor technology with a great need for on-line process control. Development of thin (80 to 200 nm) BOX is a primary step toward improved device performance and cost reduction. Tight control of the BOX properties, such as the implant dose, thickness, refractive index, and composition, is required in the production. A method to characterize non-destructively BOX layer by means of FTIR normal incidence reflectance spectroscopy has been developed with a particular orientation to in-situ applications. A data reduction procedure based on multi-layer model delivers thickness and dielectric function of a thin BOX layer, and enables one to measure the implant dose with a precision of a tenth of a percent. A compact and robust FTIR spectrometer from On-Line Technologies, combined with sampling optics and sensitive detection, provides excellent signal-to- noise ratio and is well suited for a coupling with oxygen implantation machines for in-situ process control.