Browse Prior Art Database

Photolithographic Stepper Equipped With an Ablation System

IP.com Disclosure Number: IPCOM000037098D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Kaanta, CW: AUTHOR [+2]

Abstract

An improved overlay results by combining an ablation tool and image- placement measurement scheme with a photolithographic stepper tool.

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Photolithographic Stepper Equipped With an Ablation System

An improved overlay results by combining an ablation tool and image- placement measurement scheme with a photolithographic stepper tool.

To determine the location on chips to be overlayed after any layer has been processed and before resist is applied, several alignment- mark locations are measured. Measurements made before resist is applied are more accurate than after the resist is applied. Referring to the figure, marks in non-usable devices or open areas on the wafer may be used as benchmarks and stored in the stepper to give the tool x/y chip periodicity and/or locations for individual chips. The Nikon ZI measurement system can provide a more accurate measurement than a stepper. After resist is applied, two marks in open areas (non-usable devices) are ablated with an eximer laser attached on top or below the stepper's lens. Through the use of a suction or O2 source (or both), evacuate or convert the debris to CO2, removing the contamination from the wafer surface. If contamination is containable with the above mentioned techniques, other alignment marks may be exposed through ablation to enhance overlay precision. The stepper can now proceed to align to the cleared resist marks in ablated areas. The benchmarks stored in the stepper are used to adjust the stepper to the alignment mark measurements made before the resist was applied.

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