In a previous work, contributors to Critical Dimension (CD) variability intra-field were shown to come from reticle, contrast fading coming from reticle M3D fading and scanner optics fading. In addition, intra-field best focus shifts (BF) were reported. It called for a holistic assessment and control of total CD uniformity (CDU). In this work we expand the experimental validation total CDU in two ways (1) we study the local reticle variations and its translation to wafer variability by adding Aerial Image Measurement System (AIMS) into the metrology loop (2) we investigate if the observed best focus differences have impact on the 3D aspects of the resist: resist profile and local CDU at bottom and top of contact hole were measured by Atomic Force Microscopy (AFM).
On-product overlay (OPO) is an important indicator of device yield. In this work, we show that stressed thin films used in semiconductor manufacturing can be an important contributor to OPO at multiple length scales. Depending on the stress level, film thickness, and the mask design, the overlay impact can be a few nanometers for the exposure of the next lithography layer. A predictive compact model based on pattern density is developed to accurately predict this overlay impact. The model is then verified using short-loop dual damascene wafers with stress split. The predictive model opens a new opportunity for model-based mask correction during optical proximity correction to increase the overlay margin for subsequent lithography exposures.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are being applied in high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this so-called high-NA scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law for another decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this so called anamorphic lens will provide 8nm resolution in all orientations. Paired with new, faster stages and more accurate sensors providing the tight focus and overlay control needed it enables future nodes.
In this paper we will outline the advantages of High-NA, especially for managing the needed extreme low defect printing rates while maximizing the effective throughput for patterning economics. The imaging performance is being simulated based on expected surface figures of the illumination and projection optics. Next to this, an update will be given on the status of the developments at ZEISS and ASML. Buildings, cleanrooms and equipment are being constructed, mirror production is ramping up, many tests are carried out to ensure a smooth implementation.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are being applied in high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55.
The purpose of this so-called high-NA scanner, targeting an ultimate resolution of 8nm, is to extend Moore’s law for another decade.
A novel lens design, capable of providing the required Numerical Aperture, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future nodes.
In this paper we will outline the advantages of High-NA, especially for managing the needed extreme low defect printing rates while maximizing the effective throughput for patterning economics. The imaging performance is being simulated based on expected surface figures of the illumination and projection optics. Next to this, an update will be given on the status of the developments at ZEISS and ASML. Buildings, cleanrooms and equipment are being constructed, mirror production is ramping up, many tests are carried out to ensure a smooth implementation.
While EUV systems equipped with a 0.33 Numerical Aperture (NA) lens are entering high volume manufacturing, ASML and ZEISS are in parallel ramping up their activities on an EUV exposure tool with an NA of 0.55. The intent of this high-NA scanner, targeting a resolution of 8nm, is to extend Moore’s law throughout the next decade. The high-NA optical system, together with the developments in mask and resist, provides an increased contrast, key to control stochastic contributions to EPE and the rate of printing defects. A novel lens design, capable of providing the required NA, has been identified; this lens will be paired with new, faster stages and more accurate sensors enabling the tight focus and overlay control needed for future process nodes. Impact on system architecture and proposed solutions are described in this paper. In addition, we give a status update on the developments at ZEISS and ASML.
As device size continues to shrink, stochastic-induced roughness of resist features exposed by photolithography is of increasing concern to the semiconductor industry. In this paper, we propose an end-to-end approach for line roughness analysis by using the Line Roughness Module from our CDU solution family, which is a part of HMI’s metrology SEM tool the eP5. Simulated Scanning Electron Microscope (SEM) images of line/space patterns are used to verify the ability of the Module to reliably extract roughness related metrics. A set of imec EUV ADI images collected on our metrology SEM tool are analyzed by the Line Roughness Module, and wafer signature maps of various roughness metrics are obtained. These wafer maps not only help to analyze different roughness contribution sources, but also provide insights about feature roughness in a systematic way. Such information can be further used in a feedback loop to the scanner for model correction and process control.
Due to the high energy of extreme ultraviolet (EUV) photons, stochastic effects become more important at a constant dose when compared with deep ultraviolet exposures. Photoresists are used to transfer information from the aerial image into physical features and play an important role in the transduction of these stochastic effects. Recently, metal-oxide-based nonchemically amplified resists (non-CARs) have attracted a lot of attention. We study how the properties of these non-CARs impact the local critical dimension uniformity (LCDU) of a regular contact hole array printed with EUV lithography using Monte Carlo simulations and an analytical model. We benchmark both the simulations and the analytical model to experimental data, and then use the flexibility of both methods to systematically investigate the role of microscopic resist properties in the final LCDU. It is found that metal-oxide clusters should be <1 nm in diameter, otherwise granularity will have a significant contribution to LCDU. When varying resist properties to change the resist dose-to-size, we find that the LCDU scaling with dose depends on how the resist is modified. After performing an overall sensitivity analysis to identify the optimum scaling of LCDU with dose, we find a scaling of dose − 0.5 when the development threshold is modified, and a scaling of dose − 0.33 when core radius or the quantum efficiency is changed.
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