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Browse Prior Art Database

Detection of Mask Alignment Error After Photoresist Exposure

IP.com Disclosure Number: IPCOM000077834D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 32K

Publishing Venue

IBM

Related People

Gagulee, A: AUTHOR [+2]

Abstract

Lack of alignment tolerance is a limiting factor for yield improvements and tighter ground rules, for higher density integrated circuit chips.

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Detection of Mask Alignment Error After Photoresist Exposure

Lack of alignment tolerance is a limiting factor for yield improvements and tighter ground rules, for higher density integrated circuit chips.

The requirements for an acoustic probe are: (a) a small diameter quartz or other transducer with associated circuitry; and (b) suitable display equipment.

The velocity of acoustic waves in a solid medium depends on the density of the medium. Since exposing photoresist changes its density and device formation on a silicon wafer also causes changes in local density, both will cause changes in the velocity of transverse acoustic waves and cause interference.

When the probe and device are aligned, there is symmetry in the interference mode as illustrated in Fig. 1. Any misalignment of the device geometry and the exposed photoresist will cause asymmetry in the interference mode, as illustrated in Figs. 2 and 3.

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