Characterization of contact module failure mechanisms for SOI technology using E-beam inspection and in-line TEM

Electron-beam inspection (eBI) of the contact (CA) module for silicon-on-insulator (SOI) technology is discussed in this paper. Voltage contrast is used to detect CA opens in the SRAM and both CA opens and shorts in special test structures. The inspection is performed after the tungsten chemical mechanical planarization (W CMP) step. In-line transmission electron microscope (TEM) samples at select defect sites are then prepared and imaged to determine the failure mechanism. This methodology greatly enhances yield learning and provides quick feedback for lithography and etch process adjustments.