Browse Prior Art Database

Spray Development Indicator and Sensing System

IP.com Disclosure Number: IPCOM000036130D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 63K

Publishing Venue

IBM

Related People

Via, GG: AUTHOR

Abstract

In modern wafer processing for submicrometer lithographies, spray development offers many advantages over the old batch process using a recirculating development tank. In spray development, a fine mist of submicron aerosol particles is used to spray the developer (i.e., an aqueous solution of KOH or an organic solvent) over the surface of the wafer to be processed, while the wafer slowly rotates.

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Spray Development Indicator and Sensing System

In modern wafer processing for submicrometer lithographies, spray development offers many advantages over the old batch process using a recirculating development tank. In spray development, a fine mist of submicron aerosol particles is used to spray the developer (i.e., an aqueous solution of KOH or an organic solvent) over the surface of the wafer to be processed, while the wafer slowly rotates.

It is important to eliminate the formation of coalesced aerosols, which would reach the wafer surface in form of drops, damaging the area at the point of impact. Aerosol cross sectional and timed delivery uniformity are key to the successful operation of the nozzle. The aerosol mist is generated using an appropriately designed spray nozzle, usually constructed of stainless steel.

Vortices can form within the aerosol, which will modify the cross sectional uniformity and generate voids where there is no fluid at all. In addtion, the mass of the developer in the aerosol is so small that the particles will move in accordance with the transport motion: air currents within the spray area or in close proximity influence the aerosol flow. Spatial distribution of the aerosol will be perturbed and uniformity at the wafer surface affected.

The evaluation of vendor nozzles and their calibration once installed (i.e., location of the nozzle with respect to the wafer surface) both at initial tool set-up and verification of proper functioning and placement after hours of operation are important to assure proper dispersion of the developer spray.

This disclosure describes an apparatus to visualize the nozzle spray. The apparatus is designed to be incorporated in the wafer processing tool, within the wafer developing station.

Such an apparatus would allow checking: initial setting of spray head/wafer geometry fluid break-up and absence of coalesced drops

suctions and venting versus flow stability

nozzle parameters (flow-pressure) for best

uniformity

If an ultrasonic generator is retrofitted within the spray nozzle, it can also check: spray uniformity versus ultrasonic power tune-up ultrasonic generator/verify coupling

If the developer is a dangerous solvent, either for health or because of explosive hazard, it would: verify proper dispersion and exhaustion of fumes

within the constraints of uniform aerosol spatial

distribution

Fig. 1 depicts the main elements of the tool. Passive optical deflectors/baffles and protective enclosures have been eliminated to allow...