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Nonmechanical Series Production of Sapphire Styli

IP.com Disclosure Number: IPCOM000084274D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Bohg, A: AUTHOR [+2]

Abstract

Since the required sapphire styli cannot be produced by mechanical processes, the following method is employed for the series production of monocrystalline, pyramidal sapphire styli with a square (Fig. 1) or a rectangular cross section, microsharp edges (roughness < 1 mum), and an apical angle of about 60 degrees. Initially, a negative die is produced for the sapphire styli to be manufactured.

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Nonmechanical Series Production of Sapphire Styli

Since the required sapphire styli cannot be produced by mechanical processes, the following method is employed for the series production of monocrystalline, pyramidal sapphire styli with a square (Fig. 1) or a rectangular cross section, microsharp edges (roughness < 1 mum), and an apical angle of about 60 degrees. Initially, a negative die is produced for the sapphire styli to be manufactured.

Thermal oxide (SiO(2)) is grown on both sides of a bilaterally polished, n- type, (001) crystal oriented silicon wafer. The SiO(2) is subsequently removed on the bottom side by buffered hydrofluoric acid. The bare silicon boron is diffused to provide a surface concentration of 10/20/ at/cm/3/. The depth of penetration is about 5 mum. By photolithography, rectangular windows, whose edges lie exactly in the <110 > directions within the (001) surface (Fig. 2a), are etched into the thermally grown oxide on the top side of the wafer.

The wafer is anisotropically etched in a solution of ethylene diamine, pyrocatechol, and water. The bottom area is confined by the boron diffusion, whereas the side walls of the etching pit are exactly identical to the four crystallographic (111) surfaces (Fig. 2b). For crystallographic reasons, the angle between the facing sidewalls is 70.5 degrees. The wafer thus treated is used as a negative die for the production of the sapphire styli.

After the SiO(2) mask has been removed by etching, sapphire i...