0.1-μm high-aspect-ratio pattern replication and linewidth control

The process for replication of high aspect ratio Au patterns typically includes x-ray lithography, RIE and electroplating. In this paper study of linewidth of dense L/S patterns in a wide range of periods is undertaken through the replication process. Effects of exposure dose, mask-wafer gap, RIE and electroplating process parameters on linewidth are addressed. We found that RIE parameters are the main factor affecting the linewidth. Based on the result of this study, we propose to introduce a bias in the mask pattern to the linewidth. Based on the results of this study, we propose to introduce a bias in the mask pattern to compensate the linewidth changes occurring during subsequent replication steps. Most interestingly, a mask with a required bias can also be produced by a self-biased process. Bias adjustment has been demonstrated for 0.1/0.1 micrometers L/S features with aspect ratio of 6. To further increase aspect ratio, a wet process is developed. An aspect ratio of 9 is achieved for 0.1 micrometers Au L/S patterns by using the wet process. With this method, the linewidth fidelity during replication is substantially improved.