Early detection of crystal defects in the device process flow by electron beam inspection

Abstract

In this paper, we describe an inline method to reveal crystal defects in the device fabrication process by voltage contrast detection with an electron beam inspection tool. Suitably designed monitor structures are used to this purpose. The correspondence between bright voltage contrast defects and dislocations connecting the transistor source and drain is demonstrated by selective etching followed by SEM review and by TEM inspection. In addition, it is shown that the voltage contrast defects correlate with the leakage current of the dislocation monitor structures, though some electrically active defects are missed by the electron beam inspection. Possible approaches to improve the capture rate of dislocations and correlation to leakage current are discussed. Finally, the correlation between e beam inspection of dislocation monitor structures and parametric test on a 65nm DR wafer is demonstrated.

Early detection of electrical defects in deep trench capacitors using voltage contrast inspection

“…Causes of bright VC defects include trench to neighboring cell (DT-RX) bridging or connection, trench to trench (DT-DT) bridging into the bulk substrate, and breaks in the trench dielectric which generally occur right below the buried oxide. While the literature contains many works describing the use of VC inspection for in-line detection of electrical fails in semiconductor processing [3][4][5][6][7][8][9], only one work to date discusses VC inspection of eDRAM. In this previous paper, special short loop wafers were used to debug the mask open step [10].…”