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Protecting Extreme Ultraviolet Lithography Masks

IP.com Disclosure Number: IPCOM000124177D
Publication Date: 2005-Apr-11
Document File: 2 page(s) / 14K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that coats extreme ultraviolet lithography (EUV) masks with a conformal polymer and/or water soluble polymers to protect them from particles during shipping and handling. Benefits include a solution that can be easily removed during wafer fabrication.

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Protecting Extreme Ultraviolet Lithography Masks

Disclosed is a method that coats extreme ultraviolet lithography (EUV) masks with a conformal polymer and/or water soluble polymers to protect them from particles during shipping and handling. Benefits include a solution that can be easily removed during wafer fabrication.

Background

It is very important to protect EUV masks during shipping and handling between the mask shop and wafer fabrication. EUV masks are particularly susceptible to particle contamination because they do not have pellicles protecting them (due to exposure limitations). Currently, EUV masks are put in a compact to protect them during shipping and handling.

General Description

The disclosed method coats masks for shipping and handling between the mask shop and wafer fabrication. The coating is easily removed before placing the mask in the wafer exposure tool. To increase protection, the coating can also be conformal. To remove the coating later, oxygen plasma is used if the coating is a polymer, or a de-ionized water rinse is used if the coating is water soluble (see Figures 1 and 2, respectively).

Conformal coatings are thin layers of synthetic resins or polymers, which are applied to electronic devices to protect them against a variety of environmental, mechanical, electrical, and chemical problems (e.g. humidity, contamination, stress, mechanical shock, vibration, thermal cycling, and corrosion). Conformal coatings are generally classified according to the molecular structure of their polymer backbones. There are five basic types of conformal coatings: acrylic (

Type

AR

), epoxy (Type ER), silicone (Type SR), parylene (Type XY), urethane (Type UR). The coatings are further subdivided by the mechanism of their cure (e.g. heat, moisture, UV light, etc.).

Conformal coatings can be applied in a variety of ways, but chemical vapor deposition is the cleanest method. This dry, solvent-free coating process is designed to coat PWAs and other assemblies with a thin, inert, and highly conformal polymer film known as pa...