Fabrication of Sub-0.1 μm Fine Metal Lines Using High Resolution Electron Beam Techniques with Contamination Resist

Abstract

Along with the interest in decreasing the size of the devices used in microelectronics, there is also a great deal of interest in determining the physical properties of these small devices and, in particular, the properties of the fine metal lines used in them. These fine metal lines are already known to exhibit many interesting physical properties in their own right such as Josephson effects and electron localization. Many new techniques and processes are necessary in order to fabricate and test fine metal lines with thicknesses of about 10 to 30 nm and with linewidths less than 0.1 μm. Experiments to develop such techniques are in themselves very useful in extending our knowledge of the limits of present day lithography and in discovering the physical processes that may limit the density and complexity of the structures used in future large scale integrated circuits. The main fabrication processes described in this paper utilize high resolution electron beam techniques, thin (window)substrates and contamination resist in addition to a variety of thin film fabrication processes. In addition to forming single fine lines, more complex patterns such as multi-voltage probe samples, bridge SQUIDS and circular loops can be fabricated using these techniques. Many other patterns are also possible, demonstrating the versatility of electron beam writing. It is worth emphasizing that, in addition to its use in the fabrication of the fine lines, electron microscopy, both transmission (TEM) and scanning (SEM), is also used extensively in the examination and evaluation of the fine metal lines. Other techniques2 for fine line fabrication such edge shadowing are discussed in the references and elsewhere in these proceedings.