Thermomechanical optimization of thermally actuated cantilever arrays

Scanning probe lithography (SPL) is an emerging method of producing sub 50-nm features for semiconductor applications. A new variation of this process known as Dip Pen Nanolithography (DPN) expands the range of SPL capabilities to include depositing organic and biological macromolecules with nanometer precision. Recent work has been underway to implement DPN as parallel process by employing close packed arrays of individually thermally actuated DPN probes (TA-DPN arrays). In these types of devices, it is not necessary to have feedback control of the height of individual tips during operation. This simplifies the control system and probe structure but complicates array design because of the uncontrolled mechanical interaction between the tip and surface. We have found that TA-DPN arrays are subject to several failure modes that make optimization difficult, including surface scratching, excess tip angle, and problems resulting from inadequate actuation. In this paper, these performance issues are outlined and resolved with the creation of a multi-parameter simulator. The simulation predicts array behavior by employing engineering beam theory, Hertz contact mechanics, and capillary adhesion theory. Using the new insights gained from this simulation method, TA-DPN arrays can be quickly optimized based on any desired criteria.