High-Throughput Molecular Layer Deposition for Accelerated Development of Metalcone Extreme Ultraviolet Resists

Abstract

Extreme ultraviolet lithography at a wavelength of 13.5 nm now enables sub-10 nm patterning in high-volume semiconductor manufacturing, with leading foundries producing devices at the 3 nm node. At this wavelength, only 1–2% of source power reaches the wafer, creating a photon-starved imaging environment that demands photoresist materials that combine high sensitivity, low line-edge roughness, and sub-20 nm patterning capability. Conventional polymer resists face fundamental limitations under these conditions, driving interest in metal-containing hybrid organic-inorganic films that absorb EUV photons more efficiently and convert each absorption event into localized chemical changes without diffusion-mediated blur. MLD has attracted attention for synthesizing such films, providing atomic-level control over composition through sequential, self-limiting surface reactions. However, the vast parameter space encompassing metal precursors, organic linkers, deposition conditions, and post-treatments creates a throughput bottleneck that impedes materials discovery. To address the combinatorial challenge and accelerate materials discovery, a high-throughput MLD platform was developed for photoresist screening. The system comprises six independent reaction chambers sharing common vacuum pumping and precursor delivery infrastructure, with a exclusive-access resource coordination algorithm coordinating access to prevent cross-contamination. Validation using Al₂O₃ ALD confirmed uniform growth across all chambers at 0.95 ± 0.05 Å/cycle with no detectable cross-contamination, while parallel operation reduced total processing time by 85% compared to serial deposition. The high-throughput platform enabled screening of twelve metalcone chemistries, pairing aluminum and zinc precursors with six bifunctional organic diols to form alucone and zincone films, respectively. Candidates were evaluated for growth characteristics, ambient stability, and developer compatibility. Growth rates ranged from 0.5–6.7 Å/cycle, with alucones exhibiting higher and more consistent values. Under ambient conditions, alucone films retained greater than 92% thickness after 1 h while zincone films degraded rapidly. Both film types dissolved readily in dilute aqueous acid. UV pretreatment substantially improved zincone stability, reducing thickness loss from 34% to 2.5% for BTY-zincone, but the rapid baseline degradation still precluded lithographic investigation. BTY-alucone was selected for detailed characterization based on consistent growth, a UV-sensitive alkyne linker, and effective removal by aqueous developer, though other alucone candidates remain viable for future investigation. Characterization of as-deposited BTY-alucone by XPS, FTIR, and ToF-SIMS confirmed that alkyne functionality remained intact after deposition. Electron-beam lithography at 100 keV then served as a proxy for EUV exposure to evaluate lithographic performance. Contrast curves using dilute HCl developer yielded γ = 2.19, and dose-response studies revealed concurrent processes underlying solubility switching, with rapid alkyne consumption at low doses and progressive dehydrogenation at higher exposures. High-resolution patterning demonstrated sub-20 nm features at 20 nm half-pitch with line-edge roughness of 4.9–5.9 nm. Compared to other aluminum-based MLD resists, BTY-alucone demonstrates 21–33 times higher sensitivity while requiring 300 times more dilute developer than the most sensitive previously reported metalcone resist, a hafnium-based system. Building on the alucone methodology, tincones were investigated due to tin's higher EUV absorption cross-section. Six tincone chemistries were deposited, all retaining greater than 96% thickness after 1 h ambient exposure. Developer selectivity varied with organic linker structure, ranging from complete dissolution at 0.1 M HCl for BTY-tincone to requiring 1 M or higher for aromatic linkers, providing flexibility for process integration. Collectively, these results establish high-throughput MLD as a viable methodology for photoresist screening. BTY-alucone achieves competitive lithographic performance among metalcone resists, and together with the reactor platform and tincone extension, provides a foundation for accelerated development of next-generation EUV resists.