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Contamination Protection Method for Next Generation Lithography Masks

IP.com Disclosure Number: IPCOM000012020D
Publication Date: 2003-Apr-02
Document File: 2 page(s) / 36K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for protecting a next generation lithography (NGL) mask by freezing it within a solid block of suitable material (e.g. CO2) using a condensation/sublimation process. Benefits include protecting the mask from particles and molecular contamination.

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Contamination Protection Method for Next Generation Lithography Masks

Disclosed is a method for protecting a next generation lithography (NGL) mask by freezing it within a solid block of suitable material (e.g. CO2) using a condensation/sublimation process. Benefits include protecting the mask from particles and molecular contamination.

Background

Currently, there is no solution to protect the mask from particles and molecular contamination during storage, shipping, and handling. Since a permanent pellicle is not transparent to EUV, a removable pellicle is used, but it tends to generate particles at hinges and/or contact points.

General Description

In the disclosed method, the mask is frozen within a block of material (e.g. CO2). This can be accomplished by enclosing the mask in a small box, then filling it with liquid CO2 transferred from a CO2 bottle (see Figure 1). The box self-pressurizes, and this forms the brick of solid CO2. This is routinely done for other applications, but may not have the particle control or CO2 density control of the actual chamber.

By changing the process variables viz.(P,T), the liquid or gaseous CO2 can be directly converted to form a solid CO2 block around the mask. The mask with the solid CO2 cover provides protection from contamination and particles. To remove the cover, sublimation is used to convert the solid CO2 into gas, which is pumped out of the pod or chamber. During sublimation, the mask is held with the pattern side down, so gravity...