Micromechanical sensor fabrication process

US5282924A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Thomas Bayer · Igersheim, DE
• Johann Greschner · Neckartenzlingen, DE

Key dates

• Filing date: Mar 22, 1993
• Grant date: Feb 1, 1994
• Expiry date: Mar 22, 2013

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S977/878
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method for producing micromechanical sensors for the AFM/STM/MFM profilometry is described in which a multiple step mask of cantilever beam and tip is transferred step by step into the wafer substrate by reactive ion etching. A particular highly anisotropic etching step is used for etching and shaping of the tip. This process step uses an Ar/C12 ambient at a pressure of about 100 .sup.6 bar and a self bias voltage of about 300 V DC. The ratio of pressure to self bias voltage determines the concave shape of the tip side-walls. This etching step is followed by a thermal oxidation step. The oxidation is carried out for a time until the oxidation fronts at the thinnest point of the tip shaft touch each other. A stripping process with buffered hydrofluoric acid gently removes the thermally grown oxide. The oxidation process allows--via oxidation time--a modification of tip height and angle in an extremely controllable manner. To prevent sticking of the tip to the structure to be profiled the ratio of tip diameter to tip height should be about 1:10. Should this ratio be exceeded the tip has to be arranged on a pedestal. The structure, comprising a cantilever beam and a tip on pedestal,…