The beginning of electron beam lithography dates back to the early 1980s when the first PMMA resists were developed, with chlorobenzene as first solvent. This solvent most efficiently dissolves the various PMMAs (with different molecular masses of 50K to 950K)
A typical problem arising from an extreme resolution at an aspect ratio of > 10 is the collapse of bar structures. In Fig. 1, 10-nm bars with a pitch of 50 nm are displayed. These structures were realised with CSAR 62 (SX AR-
The general aim of electron beam lithography is to achieve a maximum resolution, and therefore mostly very thin layers are used (50 – 500 nm). In a few cases however also very small structures with high aspect ratio are of interest.
Allresist designed an e-beam resist which produces, depending on the respective exposure dose used, a three-dimensional resist profile.
For the lift-off of high-resolution structures in a two-layer process, PMMA resists (90K and 200K) were adjusted to yield a film thickness of 90 nm to 100 nm. This resist system is particularly well suited for the fabrication of sub-
Utilizing SX AR-P 640/2 (PMMA 90K) as one layer system, an even higher resolution can be achieved if process parameter are varied, in particular the exposure dose.
First experiments with our SX AR-P 5000/82.7 using e-beam lithography clearly demonstrated that this resist can easily be patterned which offers the possibility to generate nanostructures which are thermally stable up to 350 °C.
A process-stable, sufficiently sensitive e-beam resist with a resolution of about 30 nm is urgently needed to accelerate the progress in electron beam lithography.
The success story of electron beam lithography began in the 1980th with the development of the first PMMA resists. These resists are absolutely light-insensitive in the UV-wavelength range above 300 nm.
E-beam resists (electron beam resists) are designed for electron beam and deep UV applications for the fabrication of highly integrated circuits, mainly for mask fabrication. They are employed in electron beam direct writing and multilayer processes.