Most of the nano-scale fabrication at Almaden is based on patterning with electron beam lithography, using a Leica/Vistec VB6 electron beam lithography tool. In general, we use this tool and a host of subtractive and deposition processes to fabricate prototype devices and structures. Although this approach is very versatile and has very high resolution, it is intrinsically a serial writing process, and therefore relatively slow. So we are also investigating alternative nano-fabrication techniques, based on nano imprint lithography, self-assembly, and optical interference lithography. In nano imprint lithography we use electron beam lithography to make a topographically patterned "master" that can be used to imprint patterns onto many samples in a single, rapid, imprinting step. In the case of self assembly, we are studying systems such as block co-polymers that assemble spontaneously into nano-patterns. Here the challenge is to direct the assembly to get the desired patterns with the required placement. Finally, we are using optical interference between colliding laser beams to directly write grating structures with very high line densities, allowing us to test a range of new resist chemistries and opening up a range of fabrication possibilities.
Figure 1. VB6 electron beam lithography machine.