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CTV News
31-05-2025
- General
- CTV News
Fluoride returning to this city's drinking water
Fluoride has been added back into the drinking water in Calgary leads MedicalWatch for May 30, 2025.
Yahoo
25-03-2025
- Science
- Yahoo
China's breakthrough solid-state deep ultraviolet laser could transform chipmaking
Scientists from the Chinese Academy of Sciences (CAS) have reportedly made a major 'breakthrough' in solid-state deep ultraviolet (DUV) lasers. A paper published in a journal by International Society for Optics and Photonics (SPIE) has revealed that researchers from China have created a coherent 193 nm (nanometer) beam used for semiconductor photolithography. If scaled up, the new technology could be used to build lithography tools that make chips using advanced process mechanisms. At present, advanced semiconductor chips used in many electronics (like cellphones, computers, etc.) heavily rely on photolithography to work. This process involves etching patterns onto silicon wafers using special ultraviolet (UV) lasers. The industry standard for DUV lithography uses a 193 nm wavelength of UV light produced by gas-based excimer lasers. Now, researchers at the CAS claim they've successfully demonstrated an experimental solid-state laser system that emits this crucial wavelength without using gases. Smaller wavelengths can produce finer and more precise patterns. The 193 nm resolution is critical because it is ideal for making high-performance semiconductor chips. It is also the reason why semiconductor lithography machines by companies like ASML, Canon, and Nikon rely on this exact wavelength. Lithography machines generally use a mixture of Argon (Ar), Fluorine (F), and Neon (Ne) gases inside a sealed laser chamber to function. When functional, a high-voltage pulse excites these gases, briefly creating a short-lived Argon Fluoride (ArF) molecule (an 'excimer'). The excited ArF molecule quickly returns to its stable state, emitting a UV photon at exactly 193 nm wavelength. The pulses delivered by lasers are powerful, typically clocking around 100–120 Watts, at 8–9 kHz frequency. While these gas lasers are reliable and widely used, they're complicated and expensive, requiring careful handling of toxic gases like fluorine. On the other hand, the new CAS laser is a fully solid-state laser, requiring no gas and only employing crystals and optics. The team achieved this by using a Yb:YAG crystal amplifier to generate infrared laser light at 1030 nm wavelength. This beam is then split in two using nonlinear optics to produce a 258 nm beam through Fourth-Harmonic Generation (FHG). Another portion of the 1030 nm beam creates a different wavelength (1553 nm) via an optical parametric amplifier (OPA). The two wavelengths are combined using special nonlinear crystals (cascaded Lithium Triborate or LBO crystals) to produce a coherent beam at 193 nm wavelength. Solid-state means fewer toxic chemicals, no fluorine gas, safer operation, lower operational complexity, and possibly lower maintenance requirements. In general, solid-state lasers tend to be more compact and reliable. However, there are certain downsides, the CAS laser's power is only 70 mW, compared to the 100–120 Watts from commercial excimer lasers. This is several hundred times weaker, making it unsuitable for mass semiconductor production at its present state. The new laser is still in the early experimental phase. Scaling it up or increasing its power output to match current commercial lasers is a significant engineering challenge that might require years or multiple generations of technological refinement. Hence, for now, significant technological hurdles remain, primarily around achieving higher power outputs and maintaining long-term reliability at industrial scales. Findings of the research have been published in the SPIE affiliated journal Advanced Photonics Nexus.
