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Browse Prior Art Database

Dry Point Detection System

IP.com Disclosure Number: IPCOM000087076D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Fontanarosa, PR: AUTHOR [+3]

Abstract

A problem that has plagued the process engineer as well as the equipment engineer in an automated photolithographic semiconductor wafer processing line is "how dry is dry" or when is a product surface, such as a semi-conductor wafer, dry enough to place into the next piece of process equipment? Disclosed below is a system for detecting and measuring the wetness of surfaces to determine when the surface is dry enough to put into a furnace or metallizer. If a wet wafer is placed, for example, in a diffusion furnace, contamination can and often does occur. If a wet wafer is placed in a metallizer, an increase in pump-down time occurs which contaminates the process chamber interior and may cause adhesion problems on the wafer.

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Dry Point Detection System

A problem that has plagued the process engineer as well as the equipment engineer in an automated photolithographic semiconductor wafer processing line is "how dry is dry" or when is a product surface, such as a semi-conductor wafer, dry enough to place into the next piece of process equipment? Disclosed below is a system for detecting and measuring the wetness of surfaces to determine when the surface is dry enough to put into a furnace or metallizer. If a wet wafer is placed, for example, in a diffusion furnace, contamination can and often does occur. If a wet wafer is placed in a metallizer, an increase in pump-down time occurs which contaminates the process chamber interior and may cause adhesion problems on the wafer.

Wet processors utilizing a dry knife technique for drying the wafer, such as the apparatus illustrated in IBM Technical Disclosure Bulletin, Vol. 16, No. 8, January 1974, p. 2696, require a drying time of approximately one minute. It requires several passes of the drying knife to wipe the wafer clean of, for example, deionized water or other process chemicals. If a dry point detection system is utilized, the wafer may be dried and delivered without excessive drying time but before it is truly dry. With the present technique, it is possible to "measure" the thickness of the liquid layer between knife passes while, with a simple evaporation-type drying technique, a continuous measurement is employed.

Referring to Fig. 1, a wafer, having a layer of liquid thereon, is positioned so that the beam from a laser will impinge upon the liquid surface on the wafer. Re...