Low-damage direct patterning of silicon oxide mask by mechanical processing.

Shojiro Miyake,Shohei Yamazaki

doi:10.1186/1556-276x-9-269

Abstract

To realize the nanofabrication of silicon surfaces using atomic force microscopy (AFM), we investigated the etching of mechanically processed oxide masks using potassium hydroxide (KOH) solution. The dependence of the KOH solution etching rate on the load and scanning density of the mechanical pre-processing was evaluated. Particular load ranges were found to increase the etching rate, and the silicon etching rate also increased with removal of the natural oxide layer by diamond tip sliding. In contrast, the local oxide pattern formed (due to mechanochemical reaction of the silicon) by tip sliding at higher load was found to have higher etching resistance than that of unprocessed areas. The profile changes caused by the etching of the mechanically pre-processed areas with the KOH solution were also investigated. First, protuberances were processed by diamond tip sliding at lower and higher stresses than that of the shearing strength. Mechanical processing at low load and scanning density to remove the natural oxide layer was then performed. The KOH solution selectively etched the low load and scanning density processed area first and then etched the unprocessed silicon area. In contrast, the protuberances pre-processed at higher load were hardly etched. The etching resistance of plastic deformed layers was decreased, and their etching rate was increased because of surface damage induced by the pre-processing. These results show that etching depth can be controlled by controlling the etching time through natural oxide layer removal and mechanochemical oxide layer formation. These oxide layer removal and formation processes can be exploited to realize low-damage mask patterns.

Highlights

In nanotechnology, nanoelectric devices and nanomachines can be manufactured by manipulating atoms and molecules [1]
We evaluated the dependence of etching depth on KOH solution etching time [26]
Mechanical processing was performed using diamond tip sliding with an atomic force microscopy (AFM) under atmospheric conditions at room temperature and humidity ranging between 50% and 80%

Summary

Introduction

Nanoelectric devices and nanomachines can be manufactured by manipulating atoms and molecules [1]. Scanning probe microscopy (SPM) is useful for the nanofabrication of nanometer-scale engineering materials and devices [2] and can be used to realize atomic-scale fabrication. The local oxidation technique is expected to allow the fabrication of electric devices on the nanometer scale [5,6,7]. The oxide layers formed by this technique can function as a mask during the etching step or can be used directly as an insulating barrier [7]. In this method, oxidizing agents contained in surface-adsorbed water drift across the silicon oxide layer

Methods

Results

Conclusion