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Reduction of Second Order Alignment Error

IP.com Disclosure Number: IPCOM000037529D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Sweetser, RW: AUTHOR

Abstract

By printing a first portion of a standard alignment aid on one mask level and a second portion of the aid on a next mask level, mask alignment of the mask for the third level and all following levels is a best fit to the two previous levels of alignment. By this means, second order alignment error (misalignment to images made prior to images last formed) are reduced.

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Reduction of Second Order Alignment Error

By printing a first portion of a standard alignment aid on one mask level and a second portion of the aid on a next mask level, mask alignment of the mask for the third level and all following levels is a best fit to the two previous levels of alignment. By this means, second order alignment error (misalignment to images made prior to images last formed) are reduced.

Referring to the table below, a standard alignment aid is comprised of segments A + B, where A is, e.g., a set of horizontal lines, and B is, e.g., a set of vertical lines. On the first line of the table, the number of the mask level used to print a segment of the alignment aid is given. On the second line of the table, the two segments A and B that make up a single alignment aid are shown below the mask level in which the segment is printed. On the third line of the table, the number of the mask level which is aligned to aids comprised of segments A + B is given: Print at Level 1 1 2 1 3 2 4 3 5 4 ---

Aid Segments A B A B A B A B A B

Align Mask Level 2 3 4 5 6 --- Thus, the level 1 mask is used to print both the A and B segments of alignment aids to which the level 2 mask is aligned plus the B segment of aids to which the level 3 mask is to be aligned. Level 3 alignment aids are completed by printing the A segments with the level 2 mask which also prints the B segments of aids to which the level 4 mask is to be aligned, etc.

Second order error reduction is a...