Browse Prior Art Database

Use of A Venturi to Accomplish Resist Splatter Dispersal

IP.com Disclosure Number: IPCOM000083135D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Related People

LaRue, AJ: AUTHOR

Abstract

Described is various means for preventing the photoresist, being deposited on a spinning wafer, from rebounding in droplet form on the wafer surface.

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Use of A Venturi to Accomplish Resist Splatter Dispersal

Described is various means for preventing the photoresist, being deposited on a spinning wafer, from rebounding in droplet form on the wafer surface.

The application of thin films, such as photoresist, on surfaces is often accomplished by depositing the film material in a liquid state in the center of the wafer to be coated and rotating the wafer at high speed, in order to effect a uniform distribution of the photoresist coating over its entire surface. This high- speed rotation results in centrifuging excess coating material beyond the perimeter of the wafer being coated. Since it is desirable to perform such operations in limited areas, the centrifuged excess material often strikes the surrounding enclosure with such force as to cause droplets of the material to rebound back onto the surface of the material being coated, resulting in unevenness in the coated surface.

In microcircuit technology, such as in semiconductor processing, such unevenness in the coating is undesirable and detrimental to the performance of the resulting product. In order to eliminate or at least greatly reduce any tendency for such droplets to rebound onto the surface being treated, some means are required to deflect droplets in such a way as to prevent their rebounding onto the surface being treated.

The figure illustrates such a coating apparatus and comprises a housing 10 surrounding a rotatable spindle 11, upon which is supported a semiconductor wafer 12. This housing 10 has a supporting wall 13 which extends up around the rotating wafer 12. Fixed to the top of the supporting wall 13 is a venturi guard 14, whose inner surface 15 is contoured to produce laminar flow of air into the cavity surrounding the wafer 12.

The coating material is deposited, on the spinning wafer, from a dispensing nozzle 16 supported by a hub 17 whose cross section is in the form of an inverted tear drop. This ellipsoidal nozzle support 17 utilized the air currents of the exhaust system, in helping to prevent splatter from being deposited on the wafer surface. Air as it enters the machine exhaust system is made to do so around the ellipsoidal nozzle support 17 supporting th...