Browse Prior Art Database

Mask To Wafer Alignment System

IP.com Disclosure Number: IPCOM000079909D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Feder, R: AUTHOR [+3]

Abstract

A visual technique for aligning two objects employs means located between the objects to form superimposed images of the objects. The system is especially useful in the alignment of shadow masks with semiconductor materials in x-ray exposure systems.

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Mask To Wafer Alignment System

A visual technique for aligning two objects employs means located between the objects to form superimposed images of the objects. The system is especially useful in the alignment of shadow masks with semiconductor materials in x-ray exposure systems.

Shadow mask 1 has desired structure 2 which is to be aligned with structure 4 on wafer 3 such as for resist exposure. In x-ray exposure, a relatively large separation of mask 1 and wafer 3 in the order of 1 millimeter is permissible. This allows the use of an optical system between mask 1 and wafer 3 surface to provide high-resolution superimposed images of structure 2 and 4. For example, prism 5 with reflecting surfaces is placed between mask 1 and wafer 3

Illumination of mask 1 and wafer 3 surfaces is accomplished using standard top illumination composer light source 11 and lens 12 with beam splitter 9, located between eyepiece 8 and objective lens 6, introducing the light. Objective lens 6 such as a commercially available microscope objective having a numerical aperture of 0.25 or greater is used, to form superimposed images of structure 2 and 4 at plane 7. The images can be viewed by eye through eyepiece 8 or by use of closed-circuit television techniques. The relative position of mask 1 and wafer 3 is then adjusted to properly align structures 2 and 4.

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