Toshiaki Kawabata

Deflection error due to charge-up effect of reticle substrate

The budget of reticle pattern placement error, using variable-shaped step and repeat electron beam writer has been studied. There are three major factors in the reticle writing process, the stage moving accuracy, the electron beam deflection accuracy and the charge-up of dielectric layers such as resist on the blanks. The charge-up of the blank surface causes the distortion error in the deflection field and the butting error surrounding exposure fields boundary. Moreover, the charge-up of the substrate strongly depends on the amount of the incident electron beam which penetrate the blank surface. Moreover, the charge-up of the blank surface causes registration error in the phase-shift mask manufacturing process. Because the alignment mark used to be exposed by the electron beam whose damage was more than that of pattern writing. In this paper, we report on the result with a variable-shaped step and repeat electron beam reticle writer focusing on the influence of the pattern density which effects a change in the charge-up of the blank surface and on the impact of overlay error in the second exposure process. In addition, we describe placement accuracy by applying electron conductive layer to the blank surface.