Calibration standard for 2-d and 3-d profilometry in the sub-nanometer

Abstract

A calibration standard comprises a supporting structure (1) of single crystal material with at least one pair of different kinds of structures consisting of a raised line (2) and a trench (3). These structures have the identical width in the range of about 500 nm. The single crystal material preferably is silicon with (110)-orientation. A method of producing the calibration standard comprises the steps: providing two polished wafers of the same single crystal material and with the same crystal orientation, forming an oxide layer on the polished surface of the first wafer, bonding the second wafer to the first oxidized wafer with the polished surfaces of the wafers facing each other, cutting the bonded structure transverse to the polished surfaces, selectively etching both the wafers to a defined depth to expose a portion of the oxide layer, masking the portions of the oxide layer now representing the raised line (2) and selectively etching the oxide layer in the unmasked areas to a defined depth to form the trench (3). The calibration standard overcomes the problem of measuring the diameter of an ultrafine tip for AFM/STM profilometry in the sub-nanometer range.