Effect of electron-beam parameters on critical-dimension measurements

Abstract

Electron scattering by electron-beam mask with tapered aperture in cell projection lithographyIn critical-dimension ͑CD͒ measurements of resist patterns, CD deviation dependent on measurement time and adjacent pattern effect are major problems created by using an electron beam. We studied the mechanism of these effects. The dependence of CD deviation on measurement time may be caused as a result of compound effects of resist thickening due to surface contamination and resist thinning due to electron-beam induced resist contraction. The adjacent pattern effect is mainly produced by surface charging. The surface charge may distort the electron-beam trajectory.

Evaluation of total uncertainty in the dimension measurements using critical-dimension measurement scanning electron microscopes

“…3 Measurements with an electron beam of 1 keV and an electron beam of 200 keV were carried out in the following procedures: ͑1͒ a linewidth of 0.3 m resist lines was measured in each space L b ; ͑2͒ the resist lines were covered with a thin conducting film to avoid the accumulation of surface charges; ͑3͒ the linewidth was remeasured L c ; ͑4͒ the difference between the two measurements was calculated in each space L b ϪL c ; ͑5͒ poly-Si etching and resist removal were carried out; ͑6͒ the linewidth of the etched line was measured in each pitch L e ; ͑7͒ the difference between the two measurements was calculated L e ϪL c . It may be possible to reduce the effect of contamination technically, but it is difficult to reduce the effect of surface charging in the low-energy electron beam measurements: the problem of surface charging seems to be more serious than that of con- tamination.…”

“…3 Surface charges deflect and accelerate/decelerate the electron beam, the deflection causes a shift of the electron beam ␦w ch , and the acceleration/deceleration brings about a defocus ␦ f ch as shown in Fig. 3 Surface charges deflect and accelerate/decelerate the electron beam, the deflection causes a shift of the electron beam ␦w ch , and the acceleration/deceleration brings about a defocus ␦ f ch as shown in Fig.…”

“…Monahan et al, have reported statistical methods and procedures to differentiate the error related to CD-SEM design from the process-induced variation. [2][3][4][5] [2][3][4][5] …”