Browse Prior Art Database

Alignment Target

IP.com Disclosure Number: IPCOM000044148D
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Marugg, TL: AUTHOR

Abstract

This article describes an alignment target of minimal complexity for use by both human operators and automated alignment equipment in which the range of aligner is extended beyond the field of view and target recognition is unaffected by orientation and permits explicit calculation of movement required to achieve alignment. The target shown in Fig. 1, processed onto the wafer, is viewed through a hole in the opaque mask. This hole should be large enough for a human operator to see the center portion of the target. Patterns currently in use suggest a diameter of approximately 1.0 mm. for the mask hole and 0.3 mm. for the central target element. The central target element 10 is surrounded by a pattern of satellite elements 11, placed so that in alignment they are not visible through the mask hole.

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 53% of the total text.

Page 1 of 2

Alignment Target

This article describes an alignment target of minimal complexity for use by both human operators and automated alignment equipment in which the range of aligner is extended beyond the field of view and target recognition is unaffected by orientation and permits explicit calculation of movement required to achieve alignment. The target shown in Fig. 1, processed onto the wafer, is viewed through a hole in the opaque mask. This hole should be large enough for a human operator to see the center portion of the target. Patterns currently in use suggest a diameter of approximately 1.0 mm. for the mask hole and 0.3 mm. for the central target element. The central target element 10 is surrounded by a pattern of satellite elements 11, placed so that in alignment they are not visible through the mask hole. As the wafer is moved out of alignment, the central target element moves toward the edge of the mask hole, and at least three satellites come into the field of view before the central target element becomes obscured, as shown in Fig. 2. Human operators will be able to identify the central target element for rough alignment, consistent with current procedure. Fine alignment could be determined with a microscope by observing satellite intrusion into the field of view, as shown in Fig. 3. Automated alignment equipment can use machine vision system with region analysis capability, and target element types can be identified on the basis of region parameters, s...