Study on Nanoscale Temperature Distribution for the Patterning of Self-Assembled Monolayers Using Near-Field Photothermal Desorption

Abstract

We propose a novel patterning method for self-assembled monolayers (SAMs) using near-field photothermal desorption (NPTD). This paper reports the patterning principle and the study on optimum heating conditions. The proposed method utilizes the thermal desorption of constituent molecules of a SAM through the irradiation with near-field light, which can make noncontact and noncontaminating patterning of the SAMs at the nanoscale. In order to verify the validity of the proposed patterning method for SAMs, the preliminary patterning of a SAM by irradiating with a laser beam was performed. The results suggested that the constituent molecules were thermally desorbed and the subsequent modification of another kind of a SAM was successfully carried out. The numerical analysis of the temperature distribution after heating with near-field light was demonstrated by using the finite element method to investigate the heating condition of NPTD. The simulation results of laser heating well agreed with the preliminary experimental results, therefore, the applicability of the proposed analytical model was confirmed. Furthermore, the analytical results of the temperature distribution indicated that the local heating at the nanoscale with sufficient temperature increase for NPTD could be induced by the irradiation with near-field light generated by using an apertured fiber probe coated with Ag. As a result, the validity of the patterning principle and the optimal heating conditions were verified, and therefore, the possibility of the nanoscale patterning of SAMs using NPTD was confirmed.