The critical dimensions (CD) change by the process delay is the most critical issue to apply the chemically amplified resists (CAR) for photomask fabrication. In the photomask fabrication processes, the resist should have both post coating delay (PCD) and post exposure delay (PED) stability, while keeping higher sensitivity. To achieve this requirement, overcoat process has been examined for the purpose of CD stabilization in CAR process for photomask manufacture. The material, which consists of hydrophobic polymer and PAG, was used for the overcoat in this study. Consequently, it has become clear that pattern formations have been possible without unnecessary thickness loss. Moreover, it has been proved that the overcoat shows the effect of controlling CD change and improvement of CD uniformity. From these results, it is thought that the overcoat process is promising for the size stabilization in photomask manufacture for devices less than 90 nm.
The critical dimensions (CD) change by the process delay is the most critical issue to use the chemically amplified resists (CAR) for photomask fabrication. In the photo-mask fabrication processes, the resist should have both post coating delay (PCD) and post exposure delay (PED) stability, while keeping higher sensitivity. To achieve this requirement, overcoat process has been examined for the purpose of CD stabilization in CAR process for photomask manufacture. The material, which consists of hydrophobic polymer and photo acid generator (PAG), was used for the overcoat in this study. It has been proved that the overcoat shows the effect of controlling CD change, and applying the overcoat does not generate a fatal number of defects and pinholes. From these results, it is thought that the overcoat process is promising for the size stabilization in photomask manufacture for 100 nm devices.
Be accompanied with gate length will tend to be smaller in LSI manufacturing, assist bar type OPC masks are vigorously investigated to take into mass production. In this research, we examined problems about manufacturing and guarantee of assist bar type OPC masks. We applied 50KeV-accelerated Vector-type E-beam system to mask manufacturing that is going to be a major equipment from now on. Firstly, we remarked the CD error that occurred in mask manufacturing, and the error was valuated. Secondly, we estimated the influence of mask accuracy to false defect occurrence. Lastly, we made the masks for defect check. The defects of the masks were measured using SEM, and wafer printability of the defects was checked by simulation. And we estimated the sensitivity of inspection. As results, it is proved to be possible that manufacturing and inspecting the assist bar type OPC masks in 100 nm node.
Improvement of Critical Dimension (CD) accuracy is one ofthe most important issues for high-end reticle fabrication. Two major obstacles remain even after careftil CD optimization efforts. One is foggy effect, which is related to writing system, and the other is loading effect, which is related to dry etching mechanism. Both of two are strongly related to pattern layout and major causes to degrade CD uniformity and mean to target. To solve those problems, we have tried to apply foggy effect correction software tool on the JBX-9000MV developed by JEOL. At this time, we used Chemically Amplified (CA) negative tone resist with optimized process condition and exposure parameter such as Proximity Effect Correction (PEC). After careful examination, we confirmed that the software could eliminate CD error caused by foggy effect. Further, by optimizing foggy effect correction, we were quite successful to compensate CD error caused by loading effect too. In this way, we established high-end (l3Onm design rule) reticle production technique.
Along with the rapid generation change of lithography and widened application of OPC, the process for High Accelerated Voltage E-Beam reticle is changing from Wet Etching to Dry Etching. Establishment and optimization of Dry Etching process becomes urgent need for mask manufacturers. However, the current resist commonly used for Dry Etching has a problem, which is resist film thickness loss on high pattern density area. Unless we can solve this problem, we can not say the Dry Etching process is suitable for next generation lithography. We selected and evaluated Chemically Amplified (CA) Resist to improve Dry Etching process of high-accelerated E-Beam. At first, as a reference of present quality, we evaluated both Dry Etching and Wet Etching process with a non-CA resist, which is commonly used. As a result advantages of Dry Etching over Wet Etching are confirmed in Linearity, pattern profile and resolution. But the problem of Dry Etching, which is pattern dependent CD variation caused by the uneven loss of resist thickness was also materialized. It is also confirmed that the amount of resist thickness loss is strongly related to pattern density. Then we did basic evaluation about several CA resists. As a result, it was confirmed that CA resist had advantages over non-CA resist on almost all aspects such as Contrast, film thickness loss and cross-sectional profile. And CA resist also solved the problem of resist thickness loss related to pattern density, which we observed when we used non-CA resist. Among several candidates, we selected one CA resist which has high contrast, vertical cross sectional profile, and enough remaining film thickness. We decided that the resist is suitable for Dry Etching optimization, then we did patterning evaluation using this resist. As a result the reticle quality was satisfactory. We could confirm big improvement on both pattern dependent CD variation and pattern profile compared to Dry Etching process using non-CA resist.
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