Pt-W alloy absorbers for high-NA EUV lithography: tunable optical and etching performance

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Manufacturing

Background:

• Extreme ultraviolet lithography (EUV) is crucial for mass-producing nanoscale integrated circuits, with advanced high-numerical-aperture systems targeting 3 nm nodes.
• Conventional tantalum-based absorbers in EUV masks exhibit limitations in resolving fine patterns required for next-generation semiconductor technology.

Purpose of the Study:

• To investigate platinum-tungsten (Pt-W) alloys as novel absorber materials for EUV masks, addressing limitations of current tantalum-based options.
• To evaluate the imaging performance, manufacturability, and etchability of Pt-W alloys compared to traditional EUV mask absorbers.

Main Methods:

• Exploration of platinum-tungsten (Pt-W) alloys as alternative EUV mask absorber materials.
• Alloying platinum (Pt) with tungsten (W) to enhance etchability using fluorine-based gases.
• Utilizing simulations to assess imaging performance, mask 3D effects, exposure dose requirements, and etching characteristics of Pt-W alloys.

Main Results:

• Pt-W alloys demonstrate superior optical properties and enhanced etchability compared to pure platinum, without compromising EUV absorption or phase-shifting capabilities.
• Simulations indicate that Pt-W alloys improve imaging performance and reduce mask 3D effects, requiring lower exposure doses than pure Pt.
• Increased tungsten content in Pt-W alloys leads to higher etch rates and more vertical sidewall profiles, minimizing etch residue.

Conclusions:

• Platinum-tungsten alloys present a viable solution for next-generation EUV mask absorbers, offering improved imaging and manufacturing advantages.
• The developed Pt-W alloys overcome the etchability challenges of pure platinum while retaining its beneficial optical properties for advanced lithography.