Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Low Reflective, High Conductive, Metal Mask Photo Plane

IP.com Disclosure Number: IPCOM000046633D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Cook, FD: AUTHOR [+4]

Abstract

Present approaches in the fabrication of semiconductor masks emphasize the use of chromium or chrome oxide for the pattern formed of the transparent substrate, such as borosilicate glass or fused quartz. Chromium has been employed as a preferred medium for electron beam (EB), since the EB charge is carried off (to ground) by the low conductivity of the chromium. However, as shown in the drawing, the use of molybdenum, for mask structures, provides greater conductivity for discharge of the EB charge, while providing a low reflectivity (20-30%) for optical exposure. Conventionally, to obtain such low reflectivity the practice has been to use chrome oxides (Cr2O3, CrO3, Cr2O5) which also result in high resistivity or low conductivity in E-beam applications.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 2

Low Reflective, High Conductive, Metal Mask Photo Plane

Present approaches in the fabrication of semiconductor masks emphasize the use of chromium or chrome oxide for the pattern formed of the transparent substrate, such as borosilicate glass or fused quartz. Chromium has been employed as a preferred medium for electron beam (EB), since the EB charge is carried off (to ground) by the low conductivity of the chromium. However, as shown in the drawing, the use of molybdenum, for mask structures, provides greater conductivity for discharge of the EB charge, while providing a low reflectivity (20-30%) for optical exposure. Conventionally, to obtain such low reflectivity the practice has been to use chrome oxides (Cr2O3, CrO3, Cr2O5) which also result in high resistivity or low conductivity in E-beam applications. In contrast, molybdenum gives low reflectivity, without the need to resort to an oxide. An added and major advantage is provided by the optical density of the molybdenum which enables the use of thinner layers for the metallization of the mask, which is necessary to enable the etching of finer lines. By comparison, a sputtered layer of chrome oxide of 1200 ~ thickness gives an optical density of
2.5, whereas a molybdenum layer of 800 ~ thickness provides a like density of
2.5. When working with UV sources, one requires a density above 3.0 (readily obtained by molybdenum) in order to prevent the transmission of the radiation through the metallization which wo...