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Method for an EUV interferometric lithography technique using a phase-shifting grating and curved multilayer mirrors

IP.com Disclosure Number: IPCOM000012940D
Publication Date: 2003-Jun-11
Document File: 3 page(s) / 468K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an extreme ultraviolet (EUV) interferometric lithography technique using a phase-shifting grating and curved multilayer mirrors. Benefits include improved functionality, improved performance, and improved cost effectiveness.

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Method for an EUV interferometric lithography technique using a phase-shifting grating and curved multilayer mirrors

Disclosed is a method for an extreme ultraviolet (EUV) interferometric lithography technique using a phase-shifting grating and curved multilayer mirrors. Benefits include improved functionality, improved performance, and improved cost effectiveness.

Background

        � � � � � To study resist characteristics for next generation lithography, an exposure tool that can print very small lines is required. Without using an expensive imaging system, interferometric lithography can be used to print lines comparable to the operational wavelength. In extreme ultraviolet lithography (EUVL), the targeted critical dimension (CD) is < 30 nm. Resist materials must be available to meet the requirements of those feature sizes. To isolate the resist effect from other contributions, such as the resolution of the exposure tool, the image contrast must be almost equal to unity. No conventional solution exists to meet this requirement.

General description

        � � � � � The disclosed method is EUV interferometric lithography using a phase-shifting grating and two curved multilayer thin film (ML) mirrors. The phase-shifting grating greatly improves the efficiency of the first orders of the split light. By using two curved optics, very fine lines can be created without using expensive imaging optics.

Advantages

        � � � � � The disclosed method provides advantages, including:

•        � � � � Improved functionality due to providing an interferometric lithography technique for EUV resist screening

•        � � � � Improved functionality due to creating high-contrast fringe patterns that can be used to print fine equal lines and spaces

•        � � � � Improved performance due to a theoretical efficiency of ~32% for ±1st orders rather than the ~15% of conventional Cr-based grating

•        � � � � Improved cost effectiveness due to the use of two curved optics rather than expensive imaging optics

Detailed description

        � � � � � The disclosed method is an interferometric lithography technique for EUV resist screening (see Figure 1). A phase-shifting grating splits the incident light to generate highly efficient ±1st orders (see Figure 2). Simulation indicates a the...