Browse Prior Art Database

Semiconductor Wafer Positioning by Fluorescent Light

IP.com Disclosure Number: IPCOM000084925D
Original Publication Date: 1976-Jan-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Dreyfus, RW: AUTHOR [+2]

Abstract

A procedure has been devised for accurately positioning a semiconductor wafer having a photoresist layer thereon during the production of integrated circuits on such wafer.

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Semiconductor Wafer Positioning by Fluorescent Light

A procedure has been devised for accurately positioning a semiconductor wafer having a photoresist layer thereon during the production of integrated circuits on such wafer.

One technique for obtaining such accurate positioning of a wafer is to employ a weak beam of ultraviolet (UV) light (4358A degrees), for illuminating scattering grooves on the wafer that serve as locating marks. The scattered illuminating light is sensed in a position near the source of UV. The UV is diffracted and distorted by the photoresist layer, as well as by the grooves, and the optics for collecting the scattered 4538A degrees light must be placed above the wafer and be part of an already crowded and very critical exposure system.

The figure employs fluorescent materials within a portion of the wafer 2 that converts the 4358A degrees light to longer wavelengths, i.e., 1.1 microns. Such converted light, being in the infrared, will pass through the silicon wafer, yet have a wavelength short enough to activate an S-1 photocathode serving as part of a detecting system. The silicon wafer 2 has a SiO(2) layer 4 thereon. Layer 6 is the photoresist that must be activated by radiant energy and then developed, in order to apply suitable electrical circuitry on the SiO(2) through openings produced in the photoresist 6 by such activation and development.

Prior to the steps of applying radiant energy to the resist 6 and developing the resist, the...