Different aspect ratio pyramidal tips obtained by wet etching of (100) and (111) silicon

Different approaches to obtain sharp silicon tips with a variety of aspect ratios, for potential use in advanced microelectronics applications, were studied. Tips suited for atomic force microscopy and field emission arrays were formed by wet chemical etching of (100) and (111) single crystal silicon in KOH, TMAH and HNA etchant. Apex sharpening with thermal oxidising step resulted in tips with apex radius below 20 nm as evaluated by SEM analysis. The fabrication of silicon tips with isotropic etching on either (100) or (111) silicon confirmed that uniformity across the wafer and tip sharpness are lower with respect to anisotropically etched structures. Pyramidal tips with aspect ratios between 0.5 and 1.2 were obtained by these methods. q 2003 Elsevier Science Ltd. All rights reserved.