Diffraction-limited soft-x-ray projection imaging using a laser plasma source.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Advanced lithography techniques are crucial for fabricating micro- and nano-scale structures.
• High-resolution imaging and etching are essential for semiconductor manufacturing and scientific research.

Purpose of the Study:

• To demonstrate projection imaging of 0.1-micrometer (µm) lines and spaces using a Schwarzschild objective and extreme ultraviolet (EUV) illumination.
• To evaluate the capability of this system for microfabrication using reactive ion etching.
• To investigate the imaging of smaller features at 0.05-µm resolution.

Main Methods:

• Utilized a Mo/Si multilayer coated Schwarzschild objective for projection imaging.
• Employed a 14-nm illumination source derived from a laser plasma source.
• Fabricated etched structures on a silicon wafer using a trilevel resist and reactive ion etching (RIE).

Main Results:

• Successfully demonstrated projection imaging of 0.1-µm lines and spaces.
• Achieved pattern transfer into silicon via RIE.
• Observed low-contrast modulation for 0.05-µm lines and spaces in polymethylmethacrylate (PMMA).

Conclusions:

• The Mo/Si Schwarzschild objective combined with 14-nm laser plasma illumination is a viable approach for high-resolution projection imaging.
• The demonstrated technique shows potential for micro- and nanofabrication applications.
• Further optimization is needed to improve contrast for sub-0.1-µm feature imaging.