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Automatic Mask Detection for Electron Beam Proximity Printing Exposure Apparatus

IP.com Disclosure Number: IPCOM000122253D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Haug, W: AUTHOR [+3]

Abstract

For electron beam proximity printing (EBP) exposure, a method is proposed which permits the automatic detection of a numerical identification code on a silicon membrane mask currently used. The design of the code is such that it may also be optically evaluated by a microscope.

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Automatic Mask Detection for Electron Beam Proximity Printing Exposure
Apparatus

      For electron beam proximity printing (EBP) exposure, a
method is proposed which permits the automatic detection of a
numerical identification code on a silicon membrane mask currently
used.  The design of the code is such that it may also be optically
evaluated by a microscope.

      When a hole structure including the mask is scanned by the
electron beam, the current flow across the wafer depends on the
entire open mask area presently exposed to the beam. By suitably
selecting the mask openings, a hole structure may be prepared for
each digit 0 to 9 of the code.  With regard to the entire open area,
this structure differs such that the current measured on the wafer
may be clearly associated with the respective digit.  The numerical
code is preceded and followed by a reference pattern to be
independent of the respective beam strength and to allow the
individual code digits to be clearly detected relative to the
reference pattern.  The hole structures in the mask for the various
digits are optically detectable by a microscope. In an EBP exposure
apparatus for production purposes the size of the electron beam may
be arbitrarily modified to allow reducing the distances between two
successive code digits to the dimensions of the digit structure and
to avoid using distance values equalling at least the maximum
electron beam diameter.  Fig. 1 is a schematic of the proposed method
...