Carl Zeiss SMT

We review the development of photolithography for semiconductor manufacturing from early 1960s to the present. From the 1960s to early 1970s, contact and proximity printing were the only methods used in manufacturing, achieving a minimum critical dimension of about 4 μm. Projection lithography was adopted in manufacturing with the advent of Perkin-Elmer’s unit-magnification wafer scanners in the 1970s, and was advanced with the arrival of wafer steppers from GCA, Canon, Nikon, ASML, and others, employing mercury (Hg) arc lamps as the light source. These Hg g-line (436 nm in wavelength) machines provided about 0.8-μm practical resolution in the fab. Wafer steppers using the Hg i-line (365 nm in wavelength) came to wide use starting about 1990. Combined with off-axis illumination, i-line lithography was able to reach below 0.35 μm in resolution. Deep ultraviolet lithography using the KrF excimer laser (248 nm in wavelength) came next, entering into production at about 1997 for the 0.25-μm logic node (with a minimum half-pitch of 0.25 μm), followed by the adoption of ArF-excimer-laser lithography (193 nm in wavelength), whose initial use in manufacturing, for the 0.13-?m node of logic integrated circuits, took place in 2001. Massive transition to 193-nm lithography happened in the 90-nm node. 193-nm lithography employing water immersion entered production at Taiwan Semiconductor Manufacturing Company (TSMC) in 2007 at the 40-nm node and enabled continued geometrical scaling for more than a decade with multiple-patterning techniques. Extreme ultraviolet (EUV) lithography entered into manufacturing in 2019 and printed dense lines of 20-nm half-pitch that year. With the arrival of the 0.55 NA EUV scanner in 2024, dense lines of less than 10-nm half-pitch can now be printed. In the course of sixty-five years, photolithography achieved a greater than 400X reduction in linear dimension and enabled a 2×105 increase in areal density.

This paper presents a design methodology for a multi-directional quasi-zero-stiffness (QZS) system that can achieve vibration isolation of large bodies with high masses across a broad frequency range in all six degrees of freedom in space. The system is based on a QZS design combined with an elastic bedding approach utilizing helical compression springs. Unlike many existing QZS approaches, the proposed system satisfies practical application constraints as well as requirements common in ultra-precision manufacturing. Specifically, it eliminates conventional mechanical joints to prevent particle abrasion and avoids critical high natural frequencies within the isolation system itself. In a two-stage design process, the system is first designed for vibration isolation in all three translational directions and then extended to all six directions through the spatial arrangement of the springs. By analytically deriving and evaluating the system’s stiffness matrix, the mutual dependencies between the positions of the springs and the resulting natural behavior are investigated to determine a suitable system configuration. The findings demonstrate the feasibility of designing a QZS system capable of stable vibration isolation for a body with a mass of 2500 kg that can be tuned to achieve target natural frequencies of about 2 Hz in all six degrees of freedom, while providing internal natural frequencies of the isolation system above a target value of 1000 Hz. In comparison to a conventional vibration isolation system, reductions in the natural frequency of up to 80% were achieved.

Enhanced chip performance and miniaturization in the semiconductor industry are driven by improved lithographic capabilities, such as those of lithography systems with larger Numerical Aperture (NA). The emerging high NA Extreme Ultra Violet (EUV) lithography scanners increase the NA from 0.33 to 0.55, enabling continued shrink down to 8 nm halfpitch for lines/spaces. EUV systems with NA >= 0.75 (hyper NA) are being explored to support further cost-effective increases in device density. Our study demonstrates that hyper NA enables pattern shrink in advanced logic node designs projected in semiconductor roadmaps beyond year 2030.

At this moment, extreme ultraviolet (EUV) systems equipped with a 0.33 numerical aperture (NA) have proven themselves and are successfully applied in high-volume manufacturing. The next step is 0.55 NA and is ready to enter mass production. This so-called high NA scanner, targeting an ultimate resolution of 8 nm half-pitch, will bring multiple benefits to the semiconductor market such as reduction of process complexity, yield improvement, higher resolution enabling printability of smaller features at increased density, and cost of technology reduction. It will extend Moore's law for at least another decade. A lens design, capable of providing the required NA, has been identified; this so-called anamorphic lens will provide 8 nm resolution in all orientations. Paired with new, faster stages, and more accurate sensors providing the tight focus and overlay control, it enables future nodes. The first 0.55 NA scanner is located in the so-called high NA Lab in Veldhoven where it is interfaced with a track and operated in cooperation with Imec, Leuven. It also allows for early customer access. We will provide the backgrounds of the architecture of the high NA tool. Next to this, an update will be given on the status of the imaging and overlay performance of this exposure tool. (c) 2024 Society of Photo-Optical Instrumentation Engineers (SPIE)