An E-Beam Direct Write Process for 16M-Bit DRAMs

概要

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For obtaining a very fine wafer pattern below half micron, direct write EB lithography has charging and proximity effect problems. A method of compensating for the charging problem is to use a 40 kV proton shower irradiation process which decreases the bottom layer resistance of the trilayer resist. The charge of the electron beam is dissipated through the bottom-layer resist. As for the proximity effect, we developed a proximity effect correction software system by dosage modification. The theoretical and experimental results showed that in a 2.2-micron-thick trilayer planarizing resist system, a 0.5-micron isolated line, 0.5-micron isolated space, and 0.5-micron contact holes were simultaneously resolved in a half-micron-thick top-layer resist. The resultant half-micron-rule 16M-bit DRAM patterns were successfully obtained on uneven topography of the processed wafer using EB direct write.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
1989-12-20