This thesis first presents a novel and highly accurate methodology for investigating
the kinetics of photoacid diffusion and catalyzed-deprotection of positive-tone
chemically amplified resists during post exposure bake (PEB) by in-situ monitoring the
change of resist and capacitance (RC) of resist film during PEB. Deprotection converts
the protecting group to volatile group, which changes the dielectric constant of resist. So
the deprotection rate can be extracted from the change of capacitance. The photoacid
diffusivity is extracted from the resistance change because diffusivity determines the rate
of change of the acid distribution. Furthermore, by comparing the R and C curves, the
dependence of acid diffusivity on reaction state can be extracted. The kinetics of
non-Fickean acid transportation, deprotection, free volume generation and
absorption/escaping, and resist shrinkage is analyzed and a comprehensive model is
proposed that includes these chemical/physical mechanisms.
Then in this thesis a novel lithographic technique, liquid immersion contact
lithography (LICL) is proposed and the simulations are performed to illustrate its main features and advantages. Significant depth-of-field (DOF) enhancement can be achieved
for large pitch gratings with deep-UV light (û=248nm) illumination with both TM and
TE polarizations by liquid immersion. Better than 100nm DOF can be achieved by when
printing 70nm apertures. The simulation results show that it is very promising to apply
this technique in scanning near field optical microscopy.
Finally, a rigorous, full vector imaging model of non-ideal mask is developed and
the simulation of the imaging of such a mask with 2D roughness is performed. Line edge
roughness (LER) has been a major issue limiting the performance of sub-100nm
photolithography. A lot of factors contribute to LER, including mask roughness, lens
imperfection, resist chemistry, process variation, etc. To evaluate the effect of mask
roughness on LER, a rigorous full vector model has been developed by the author. We
calculate the electromagnetic (EM) field immediately after a rough mask by using
TEMPEST and simulate the projected wafer image with SPLAT. The EM field and wafer
image deviate from those from an ideal mask. LER is finally calculated based on the
projected image.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4233 |
| Date | 30 October 2006 |
| Creators | Liu, Chao |
| Contributors | Cheng, Mosong, Eknoyan, Ohannes |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 1169299 bytes, electronic, application/pdf, born digital |
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