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Method for a composite silicon-carbon pellicle for EUV lithography applications

IP.com Disclosure Number: IPCOM000030149D
Publication Date: 2004-Jul-29
Document File: 6 page(s) / 46K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a composite silicon-carbon pellicle for extreme ultra violet (EUV) lithography applications. Benefits include improved functionality and improved performance.

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Method for a composite silicon-carbon pellicle for EUV lithography applications

Disclosed is a method for a composite silicon-carbon pellicle for extreme ultra violet (EUV) lithography applications. Benefits include improved functionality and improved performance.

Background

              A key requirement for the success of EUV lithography is the development of pellicles for protecting the reflective masks against particles and other contaminants and to control mask defects. Due to the extremely large absorption of UV light in the ~13 nm wavelength range, few materials are suitable for the fabrication of pellicles. For the materials that may be suitable, such as silicon and carbon, the pellicles must be extremely thin but able to withstand mechanical and handling forces in manufacture and use.

              Conventional DLC films 5 nm and thinner are produced using ion-beam deposition and plasma enhanced chemical vapor deposition (PECVD) techniques.

General description

      The disclosed method is the use of silicon and diamond-like carbon (DLC) films for the fabrication of very thin pellicles. They are supported by silicon members to enable the manufacture of pellicles for EUV, which transmit >60% of the radiation in two passes.

              The key elements of the disclosed method include:

•             200-mm diameter silicon on insulator (SOI) wafers, manufactured by the layer transfer process

•             Top silicon layer that is ~100 nm thick.

•             DLC films 5-10 nm thick deposited by ion beam deposition on silicon

•             Substrate silicon thinning by grinding

•             Checkerboard pattern etched in the silicon using lithography and etching until the silicon is removed

•             Buried oxide used as a silicon etch stop, leaving a thin composite of silicon and DLC as the pellicle

•             Silicon support structures that are spaced evenly apart and not expected to interfere with UV transmission due to their narrow (~10 microns) dimensions and the spacing between the mask and the pellicle

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to providing very thin pellicles
•             Improved performance due to providing pellicle strength and scratch resistance

•             Improved performance due to providing improved transmission of UV radiation

Detailed description

              The disclosed method uses silicon and diamond-like carbon to create thin silicon membranes on silicon on insulator (SOI) wafers. DLC films provide etch resistance to the silicon membranes and confer additional mechanical strength to the structure and scratch resistance to the pellicle. The relative thicknesses of the two materials are tailored to achieve the maximum transmission of UV radiation (see Figure 1).

              Based on the transmission characteristics of silicon and carbon the disclosed method utilizes these materials for the fabrication of EUV pellicles. The higher ...