About the Center for X-Ray Optics

CXRO was established in the early 1980s by David Attwood and Jim Underwood, who recognized that the emerging generation of synchrotron light sources would require an entirely new class of optics and instrumentation. As the center’s founding director, Attwood articulated the intellectual framework for the field, championing the use of diffractive optics with short-wavelength radiation to achieve nanoscale imaging.

Attwood also played a critical role at the national level. He was a leading advocate in the effort to secure federal funding for the Advanced Light Source during the Reagan administration, making the case that the United States needed a dedicated soft X-ray synchrotron to remain competitive in materials science and physics.

While Attwood drove the scientific and policy vision, Underwood brought the engineering rigor needed to realize it. His expertise in multilayer mirrors and reflective optics ensured that CXRO’s ideas translated into working, high-performance instruments. Together, they established a culture in which physicists, engineers, and mathematicians co-designed experiments from the ground up.

CXRO’s reputation was shaped by two internally developed innovations that went on to become global standards.

The first addressed the fundamental challenge of focusing soft X-rays. High-resolution imaging required Fresnel zone plates with feature sizes beyond the reach of commercial fabrication tools. In response, Erik Anderson developed the Nanowriter, a custom electron-beam lithography system capable of unprecedented precision. The Nanowriter enabled CXRO to fabricate the world’s highest-resolution zone plates and, in doing so, made possible the first generation of soft X-ray microscopes. These advances allowed researchers to image biological cells and magnetic materials with elemental sensitivity at the nanoscale.

The second innovation focused on access to reliable X-ray data. Eric Gullikson, a student of the pioneering X-ray physicist Burton Henke, undertook the task of refining and expanding the understanding of how materials interact with X-ray light. Building on Henke’s work, Gullikson created and maintains the CXRO X-Ray Interactions Database. Today, it is the reference standard for the field, used daily by researchers worldwide to calculate X-ray transmission, reflectivity, and attenuation lengths.

As the semiconductor industry approached the limits of optical lithography, CXRO applied its expertise to the development and evaluation of extreme ultraviolet technologies. Under the leadership of Patrick Naulleau, the center became a critical bridge between synchrotron-based research and high-volume manufacturing.

Naulleau led the development of the Micro Exposure Tool (MET) and the SHARP microscope. Ken Goldberg, who served as CXRO’s deputy director under Naulleau and remains active at Berkeley Lab today, spearheaded the center’s EUV mask imaging program, beginning with the Actinic Inspection Tool (AIT) and culminating in SHARP. Goldberg also played a major role in the first MET and in the development of EUV interferometry. These instruments gave industry partners a way to test photoresists and inspect photomasks years before commercial EUV scanners were available. By aligning CXRO’s capabilities with the pressing demands of Moore’s Law, the center became an essential partner to the global semiconductor ecosystem.

Today, the Center for X-Ray Optics is entering a new phase, shaped by the transition of extreme ultraviolet lithography from a research challenge into a foundational technology of the microelectronics era. Under the leadership of Bruno LaFontaine, the center is expanding its focus beyond the immediate demands of EUV manufacturing toward the broader scientific questions that will define patterning, materials, and devices in the decades ahead.

CXRO remains a core international hub for EUV lithography research. Its actinic exposure, inspection, and metrology tools continue to support the development of next-generation photoresists, masks, and high–numerical aperture optical systems, including work on anamorphic imaging, wavefront control, and mask 3D effects that are central to future EUV scanners. At the same time, the center is increasingly leveraging these capabilities to explore how lithography intersects with emerging device concepts, including those based on low-dimensional and quantum materials.

A key example of this shift is CXRO’s growing emphasis on radiation chemistry and patterning science. As feature sizes approach molecular length scales, performance limits are no longer set solely by optics, but by the chemistry and physics of energy deposition in matter. CXRO’s development and application of resonant soft X-ray scattering (RSoXS) provides a powerful, non-destructive way to probe chemical and structural changes in photoresists during the latent stages of exposure. By revealing how reactions unfold before development, RSoXS enables new insight into line-edge roughness, stochastic effects, and material transport mechanisms that are otherwise difficult to observe.

This work is closely aligned with the CHiPPs EFRC (Center for High Precision Patterning Science), an Energy Frontier Research Center devoted to advancing the fundamental science of pattern formation. Through CHiPPs, CXRO connects EUV lithography to a broader community studying self-assembly, reaction-diffusion systems, and chemically driven structure formation. The result is a feedback loop between lithography, materials synthesis, and theory that extends well beyond conventional semiconductor scaling.

Looking ahead, CXRO is positioning itself at the intersection of advanced microelectronics, novel materials, and new device paradigms. This includes exploratory work on patterning and imaging approaches relevant to two-dimensional materials, heterogeneous integration, and nanoscale systems where traditional assumptions about resist behavior, interfaces, and dimensional control no longer hold. In this regime, the center’s long-standing strengths in optics, metrology, and data-driven modeling remain essential, but are increasingly coupled to chemistry, materials science, and computation.

Through this evolution, CXRO remains anchored in its founding philosophy: progress in short-wavelength science depends on building instruments that make new experiments possible. Whether enabling the next generation of EUV lithography or opening new windows into how matter responds to light at the nanoscale, the center continues to define the tools and techniques that shape the field.