Mask technologies for soft-x-ray projection lithography at 13 nm.

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Soft x-ray projection lithography requires precisely patterned masks for high-resolution patterning.
• Current fabrication methods for transmissive and reflective masks face challenges in achieving sub-micron feature sizes and mask repair.

Purpose of the Study:

• To describe and demonstrate various technologies for patterning high-resolution soft x-ray projection lithography masks.
• To introduce novel methods for fabricating both transmissive and reflective masks with features as small as 0.1 µm.
• To present a new technique for repairing reflective masks without compromising optical performance.

Main Methods:

• Fabrication of transmissive masks using a Ge-absorbing layer on a boron-doped Si membrane for 13 nm applications.
• Patterning of reflective masks via methods including absorber layer deposition, reactive ion etching for coating removal, and ion implantation for ion damage.
• Development and demonstration of a novel absorber repair process for reflective masks.

Main Results:

• Successfully patterned transmissive masks with features as small as 0.1 µm.
• Demonstrated multiple effective techniques for patterning reflective masks.
• Achieved the first reported absorber repair process for reflective masks that preserves multilayer reflectance.

Conclusions:

• The developed technologies enable the fabrication of advanced soft x-ray lithography masks with critical features at the 0.1 µm scale.
• The demonstrated repair technique offers a significant advancement for the longevity and usability of reflective masks.
• These advancements are crucial for pushing the boundaries of high-resolution patterning in microelectronics and other fields.