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As demand for nextgeneration chips intensifies, highharmonic generation (HHG) is becoming fundamental in semiconductor research and development. Erik Hosler, a specialist in semiconductor processes, identifies HHG as a critical asset in advancing lithography. By enabling researchers to experiment with new wavelengths and refine earlystage techniques, HHG is driving progress toward innovations that could shape the future of semiconductor manufacturing. With applications that extend from precise material testing to breakthrough photomask imaging, HHG provides a versatile platform for meeting the industry’s evolving challenges.
Flexible and Powerful: HHG’s Role in Research and Development
Highharmonic generation is proving invaluable for research and development, particularly because of its versatility and compact design. Unlike largescale lithography equipment dedicated to specific wavelengths, HHG sources can be used on a tabletop and offer tunable wavelengths for flexible experimentation. According to Hosler, this flexibility makes HHG ideal for preproduction “pathfinding activities,” especially in developing earlystage EUV mask inspection methods and highnumericalaperture EUV photomask imaging. As manufacturers push beyond the ultraviolet spectrum, HHG’s role in pathfinding is instrumental in exploring new optical methods that could support advanced lithographic applications.
Paving the way beyond EUV lithography
As the industry explores wavelengths beyond the 13.5nm EUV standard, HHG’s adaptability makes it an ideal tool for research. As one of the few tabletop sources able to explore multiple wavelengths, HHG allows researchers to conduct critical experiments on photoresist materials and optimize batch production methods, uncovering insights into molecular interactions that can refine chemical formulations. This adaptability positions HHG as essential in refining lithographic processes and developing new materials.
Technical limitations in scaling HHG
Despite its potential, HHG faces significant challenges that currently limit its application at an industrial scale, with the primary hurdle being, as Hosler explains, “HHG falls substantially short of having the average power required to facilitate lithography process at scale.” For HHG to transition into productionlevel applications, major advances in ultrafast repetition rates would be needed. Until then, HHG remains a valuable tool for R&D, laying the groundwork for nextgeneration semiconductor processes.
Supporting EUV and XRay lithography
In addition to its research potential, HHG also complements established lithographic techniques, such as EUV and Xray lithography, by providing an adaptable, costeffective platform for testing new metrology approaches. With its tunable light source, HHG enables quick and inexpensive experimentation, enabling researchers to explore highresolution inspection methods without extensive custom engineering. This flexibility reduces development costs and accelerates the path to new highvolume manufacturing (HVM) solutions. As semiconductor manufacturing grows increasingly complex, HHG stands as a valuable ally to more established tools.
Enhancing etching precision with HHG
Process control is a critical component of advanced semiconductor manufacturing, particularly in precise etching techniques like gateallaround architectures, where traditional etch stop layers have been eliminated. HHG could enhance realtime monitoring of etching processes, offering an effective alternative for process control and precision. As semiconductor designs become more intricate, HHG’s ability to support detailed, realtime process adjustments becomes increasingly valuable in the pursuit of higher accuracy and yield.
Atomicscale pathfinding with HHG
While HHG won’t directly drive atomicscale lithography due to limitations in etendue, it remains useful as a pathfinding tool for atomiclevel processes. By leveraging its inherent coherence and highprecision grating capabilities, HHG can help researchers test chemical and structural requirements for atomicscale manufacturing. Although it won’t support direct production, HHG provides crucial insights that will shape the next phase of lithography as the industry inches closer to atomiclevel technology.
HHG’s longterm role beyond EUV
Highharmonic generation is expected to play a pivotal role in shaping the future of lithography well beyond the EUV era. Hosler sees HHG as “instrumental in conducting the pathfinding research to inform the patterning, metrology, and inspection roadmap for the next decade and beyond.” With the semiconductor industry advancing toward complementary fieldeffect transistors and the use of twodimensional materials, HHG will remain an essential tool for R&D, supporting the development of atomicscale transistors.
