| Popis: |
To reach the sub-0.3 micrometer contact hole pattern by i-line lithography, some advanced technology was introduced such as Phase Shift Mask (PSM) and/or photoresist (PR) flow process. It may be possible that the contact hole is patterned with 0.18 micrometer resolution by the PR flow process with PSM. However, PSM cause the Tg temperature of resist down at the phase shift area. And it also leads the bulk effect by the different pattern density at the cell edge. Thus, during the PSM + PR flow process, 'contact shift' and 'contact distortion' (so-called 'Eyebrow') defects are unavoidable. To repel these defects, we designed the new lithographic process; the UV-bake before thermal flow process. By the UV light at 130 +/- 10 degrees Celsius, the resist was cured at the resist surface. This surface-cured resist has the higher Tg temperature even the normal PSM reticle induces the Tg down. Top surface curing (hardening) also minimized the bulk effect. To maximize the UV bake effects, we developed new resist which was optimized to UV-bake process. By UV-bake process with new resist, the 0.2 micrometer contact hole was patterned. ET margin was 14 nm/10 mJ, and DOF margin was 0.6 micrometer at the mass fabrication device. The 'Eyebrow' and contact shift defects are not detected. |
