Browse Prior Art Database

Making Iron Oxide Masks

IP.com Disclosure Number: IPCOM000077959D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Bajorek, CH: AUTHOR [+3]

Abstract

Semitransparency in the visible range and complete opacity in the ultra-violet range, is a desirable feature for masks used in photolithography. This feature should be associated with good spatial resolution, absence of defects such as pinholes, hardness and durability. Iron oxide masks possess all of these capabilities. However, the mask fabrication processes proposed in the past are rather cumbersome and complicated involving slow deposition rate of iron oxide films, difficult etching procedures and a very large number of process steps.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Making Iron Oxide Masks

Semitransparency in the visible range and complete opacity in the ultra-violet range, is a desirable feature for masks used in photolithography. This feature should be associated with good spatial resolution, absence of defects such as pinholes, hardness and durability. Iron oxide masks possess all of these capabilities. However, the mask fabrication processes proposed in the past are rather cumbersome and complicated involving slow deposition rate of iron oxide films, difficult etching procedures and a very large number of process steps.

The process described herein, allows the fabrication of iron oxide masks by a considerably simpler process entailing fewer steps than those utilized in the past.

It has been determined that approx. 1000 Angstroms thick Fe films evaporated on glass substrates can be completely oxidized, by heating the films in air for short times at temperatures > 300 degrees C. This treatment produces a semi-transparent approx. 2000 Angstrom, red Fe(2)O(3) oxide film of very uniform characteristics with good adhesion to the glass substrate and a very hard surface. By exposure and development of a surface of a permalloy film overcoated with Shipley 1350 H* or Shipley AZ-111' photoresist through an Fe(2)O(3) film, it was determined that the area masked by the Fe(2)O(3) film was not exposed. This test confirmed that the oxide film does not transmit ultraviolet light. It was also found that the oxide could be easily etched in dilute HCl acid (37%).

The following procedures allow very simple fabrication of iron masks suitable for photolithographic work.

Procedure 1
a) Evapora...