Silicon-on-insulator material qualification for low-power complementary metal-oxide semiconductor application

Abstract

To quantify silicon-on-insulator (SOI) material quality with limited or no processing requires an understanding of the correlations between material properties and device/circuit performance. We have developed robust procedures for on-line and off-line material qualification. Light point-defect detection, total reflectance X-ray fluorescence spectroscopy, atomic force microscopy, and wafer flatness measurements have been used to non-destructively qualify SOI wafers. Identification of defects has been performed by coupling scanning electron microscopy (SEM) /optical review and wet chemical etch procedures with surface defect mapping. Some of the most detrimental defects for separation by implantation of oxygen (SIMOX) wafers are caused by metal particle contamination introduced during implant. Off-line material characterization has been performed using transmission electron microscopy, SEM, Auger electron spectroscopy, secondary ion mass spectrometry, and wet chemical etch procedures. Buried oxide (BOX) and metal-oxide semiconductor (MOS) capacitors and MOS field effect transistors (MOSFETs) ( L drawn ≥ 0.2 μm) have been fabricated on 200 mm SOI wafers for correlation of material properties and device performance. BOX capacitors have been used to detect defects and contamination under the buried oxide and electrical defects in the buried oxide of SIMOX material. The defects and contamination under the BOX show spatial non-uniformities within wafers that can be correlated with similar non-uniformities during the implant process. Together, these results have assisted in defining a material qualification methodology for SOI that is well-aligned with low-power technology.