Department of Chemistry and Center for Materials Innovation, Washington University in St. Louis, Campus Box 1134, One Brookings Drive, St. Louis, Missouri 63130, USA.
Langmuir. 2010 Mar 16;26(6):4523-8. doi: 10.1021/la9033029.
We have investigated the efficiency of bifunctional pattern formation in alkanethiolate self-assembled monolayers (SAMs) adsorbed on GaAs (001) and Au, using time-of-flight secondary ion mass spectrometry. Two patterning techniques were employed: electron beam lithography and UV photopatterning. Previous work has always assumed that complete degradation of the SAM was necessary for the formation of well-defined multifunctional patterned surfaces, requiring large electron doses or long UV irradiation times. We demonstrate that well-defined multifunctional patterned surfaces can be produced on GaAs (001) with only partial degradation of the SAM, allowing greatly reduced electron beam doses and UV irradiation times to be used. Using electron beam lithography we observe that sharp well-defined patterns can form after an electron dose as low as 450 microC cm(-2). We also demonstrate that only 50% of the monolayer must be photooxidized in UV photopatterning, reducing the exposure time needed by a factor of 3. In contrast, patterning of alkanethiolate SAMs adsorbed on Au requires much higher electron doses (> or = 1250 microC cm(-2)) and photooxidation times (2 h). The substantial differences observed on these two substrates appear to arise from differences in the SAM structure on GaAs and Au. These results suggest that alkanethiolate SAM resists may be a suitable technology for nanometer scale lithography of GaAs and possibly other semiconductors.
我们使用飞行时间二次离子质谱研究了在 GaAs(001)和金上吸附的烷硫醇自组装单分子层(SAMs)中的双功能图案形成效率。我们采用了两种图案化技术：电子束光刻和紫外光光刻。之前的工作一直假设 SAM 的完全降解对于形成定义明确的多功能图案化表面是必要的，这需要大的电子剂量或长的 UV 照射时间。我们证明，仅通过 SAM 的部分降解就可以在 GaAs(001)上生成定义明确的多功能图案化表面，从而大大减少了电子束剂量和 UV 照射时间的使用。通过电子束光刻，我们观察到在电子剂量低至 450 μC cm(-2)时就可以形成尖锐的定义明确的图案。我们还证明，在紫外光光刻中只需将单层的 50%光氧化，就可以将所需的曝光时间缩短三分之一。相比之下，在 Au 上吸附的烷硫醇 SAM 的图案化需要更高的电子剂量(>或= 1250 μC cm(-2))和光氧化时间(2 小时)。在这两种基底上观察到的显著差异似乎源于 GaAs 和 Au 上 SAM 结构的差异。这些结果表明，烷硫醇 SAM 抗蚀剂可能是 GaAs 及可能其他半导体的纳米尺度光刻的合适技术。
