Polymeric Surface Alteration via Scanning Probe Microscopy

Abstract

This preliminary study focuses on the physical alteration/manipulation of three polymer surfaces (polyimide, PDMS and P(BuMA)), via the scanning probe microscope (SPM). The aim of this study is to investigate the degree of surface manipulation (lithographic outcomes) on the different polymer surfaces under similar raster scanning loading conditions. The polymeric materials were selected based on their varying degree of 'stiffness' (i.e., Young's modulus), commercial availability, potential applications. A clean incompressible silicon surface was used for calibration purposes. Manipulation (particularly on the softer polymer surfaces, PDMS and P(BuMA)) was achieved using stiff levers (i.e., > 4 nNnm-1). The resultant alteration was then analyzed using a soft lever (< 0.1 nNnm -1) to avoid further manipulation and alteration. Lithographic outcomes on a surface are not only dependant on the instrumental parameters (e.g., loading force, orientation and scan speed), but they also depend on the different Young's modulus values of the polymer. It has been demonstrated that at high Young's modulus values (> 5 GPa) no discernable lithographic outcomes have been achieved. At Young's modulus values in the low GPa range (< 2 Gpa), wells, pits and orthogonal grids have be formed. On the other hand, softer polymer surfaces (Young's modulus in the kPa range) induced a stick-slip phenomena