"NANOIMPRINT LITHOGRAPHY S"
NANOIMPRINT LITHOGRAPHY S. Glenn, D. Ewbank* and W. Johnson, Department of Microelectronic Engineering, Kate Gleason College of Engineering, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org Nanoimprint Lithography (NIL) is a low cost, high resolution, large area patterning process. NIL differs from optical lithography in that the mask is not optically binary (i.e. not composed of clear and dark areas) but contains relief structures (topography that protrudes or depresses on the mask face). NIL allows for patterning down to the sub-100nm regime while also ridding the need for the expensive lenses used in optical lithography. The goal of our exploration in NIL is to achieve equal lines and spaces using the full wafer nanoimprinting process. The procedures include (1) creating an oxygen- free, nitrogen environment using glove bags, (2) allowing oxygen to dissipate from a 2µL drop of imprint resist in this environment, (3) applying the grated mask to the resist, (4) exposing the resist to i- line radiation while in this environment, and (5), separating the mask and wafer. Being that our precursor consists of isobornyl acrylate, ethylene glycol diacrylate, butyl acrylate, and Irgacure 651, an oxygen-free environment is necessary to allow the crosslinking process to occur. After allowing the resist to sit in nitrogen for 10 minutes and be exposed at a dose of 150 mJ/cm2 for 30 seconds, a crosslinked, clear resist results. Applying the mask to the wafer after placing a 2µL drop allows for better spreading but doesn’t allow for oxygen to be released fully. The presence of oxygen causes the resist to be multi-colored and semi-crosslinked. Leaving the resist in the nitrogen for 10 minutes then placing the mask on the wafer requires some pressure to allow spreading to occur. Once crosslinked, the clear resist sticks to the mask. To prevent this, the release agent used to treat the mask is a combination of RER 600 (PGMEA) and (heptadecafluoro-1,1,2,2- tetrahydrodecyl)dimethylchlorosilane. The release agent as of this point has not helped in the separation of the mask and wafer for the resist still sticks to the mask. The authors achieved an oxygen- free imprint in clear resist as is seen in Figure 1; but most of the resist still stuck to the mask instead of the wafer. This allowed us to examine the imprint left by the mask. Figure 1: Crosslinked imprint resist with 10 µm pitch. The authors acknowledge the support provided by NSF through REU grant # ECCS-0731485.