EUV PHOTO MASKS AND MANUFACTURING METHOD THEREOF

Smart overview of the Invention

The patent application describes a reflective mask used in extreme ultraviolet lithography (EUVL), a critical process in semiconductor manufacturing. This mask consists of multiple layers, including a substrate, a reflective multilayer, a capping layer, an intermediate layer, an absorber layer, and a cover layer. The absorber layer is composed of materials such as iridium, platinum, or ruthenium to ensure high absorption and low reflectivity.

Background

Photolithography is essential in semiconductor production, using various techniques like ultraviolet and deep ultraviolet lithography. EUVL is particularly significant due to its use of short-wavelength light. A key component in these processes is the photo mask, which must have distinct reflective and absorptive regions to facilitate precise patterning on semiconductor wafers.

Detailed Description

The application provides various embodiments for constructing the EUV photo mask. These include different configurations and materials for each layer to optimize performance. For instance, the reflective multilayer may consist of alternating silicon and molybdenum layers, while the capping layer could be made from ruthenium or its alloys to prevent oxidation.

Manufacturing Method

The invention outlines methods to fabricate the EUV photo mask, focusing on preventing damage to the backside conductive layer. Techniques involve specific deposition methods for each layer, such as chemical vapor deposition or sputtering. The design ensures that the mask maintains high reflectivity for EUV wavelengths while providing robust protection against environmental factors.

Technical Specifications

• The substrate is typically made from low thermal expansion materials like fused silica.
• The multilayer stack can include 30 to 60 pairs of silicon and molybdenum layers.
• Capping layers may be between 2 nm and 10 nm thick, using materials like elemental ruthenium or its alloys.
• The absorber layer is designed to achieve less than 5% reflectivity for EUV radiation.