High NA EUV stochastic resist modeling considered with development parametersTsuzuki, R.; Liu, X.; Oyama, K.
doi: 10.1117/12.2613438pmid: N/A
In 2021 IRDS logic roadmap, required minimum contact/via pitch is 28 nm in 2025, which cannot be obtained by single exposure at 0.33 NA system using chemical amplified resist (CAR). To make the target possible, 0.55 NA system is the only way for single exposure. The relationship of resolution, roughness, and sensitivity has been known to be trade-off in CAR, and we tried optimizing them at 0.55 NA lithography simulation. For the optimization, not only resist material parameters, but also resist development parameters were adjusted. In addition, we conducted numerical simulation for line and space (L/S) pattern of metal oxide resist (MOR), which is expected as one of the breakthroughs for making narrower patterns. We set up a MOR NTD model and calibrated it by experimental data. The calibrated model is applied to the evaluation of the patterning performance including dose to size (DtS), roughness, and resist profile. Simulation results regarding a new wet development method for MOR to break through the RLS trade-off are introduced.
Pattern customization on 193 immersion lithography by negative tone development process and multiple exposuresMendes, Ivanie; May, Michael; Rêche, Jérôme; Tiron, Raluca; Sarrazin, Aurélien; Dubreuil, Olivier
doi: 10.1117/12.2614018pmid: N/A
Densification and reduction of lithographic features sizes keeping low defectivity is one of the biggest challenges in the patterning area. In order to extend 193 immersion capabilities and meet advanced applications needs, multi exposure image mode is a promising option for non-high volume manufacturing. It allows from a unique pattern with a fixed critical dimension (CD) and pitch, to obtain more dense patterns in a large surface without any process loop of standard flow, a huge benefit compared to litho-etch-litho-etch (LELE) approach. The study carried out explores this method with a specific design of pillars array printed using Negative Tone Development (NTD). The multi-image option relies on exposing multiple times the same initial pattern with a low image-to-image overlay. Based on intrinsic scanner performances, imageto-image placement error should be less than two nm. In this paper, many functionalities are explored to customize patterns from a single and unique mask design. One stake is to transfer (into silicon) a 2 mm * 2 mm pillar array design with a pitch divided by two, covering a wide surface on a 300 mm wafer and answering overlay and stitching requirements. Final results give well defined pillars which intra-wafer CD uniformity (3σ) satisfies application process requests. By using a flexible multi-image mode, mask constraints (cost and quality) can be relaxed, i.e. with a larger pitch structure on the reticle than the targeted one, final feature can be achieved. This development can be extended to hybrid lithography such as NanoImprint Lithography (NIL) or specific applications such as optics.
AIMS EUV evolution towards high NA: challenge definition and solutions implementationCapelli, Renzo; Kersteen, Grizelda; Krannich, Sven; Koch, Markus; Fischer, Lukas; Roesch, Matthias; Gwosch, Klaus
doi: 10.1117/12.2612261pmid: N/A
The road towards the next technology leap in EUV lithography is set. ASML and ZEISS have designed and started manufacturing the next generation EUV exposure tool. With a wafer side NA of 0.55, the High NA scanner system will support the further pattern node scaling roadmap by improving image contrast and therewith reduce LCDU and defect print rate on product wafer. As for all major steps in the lithography evolution, the whole infrastructure will develop further in order to support this next quantum leap in EUV technology, with the EUV photomask technologies and metrology tools representing an essential piece of the mosaic. The AIMS® EUV system represents a unique piece of the EUV mask infrastructure for the qualification of the mask printing performance in the aerial image. The AIMS® aerial image is by design targeted to match the scanner aerial image, as the tool is engineered to emulate all imaging relevant scanner properties, e.g., mask side NA, through slit chief-ray characteristics, aberration level, illumination schemes. For the emulation of the High NA scanner, ZEISS developed and started manufacturing an upgrade for the current existing 0.33NA AIMS® EUV platform. The same AIMS® EUV system is therefore capable of imaging 0.33NA isomorphic as well as 0.55NA anamorphic masks, providing the best-in-class performance for both imaging technologies and optimal match to scanner imaging. In this paper the first imaging results of the AIMS® EUV High NA tool are shown together with quantitative analysis of 0.55NA anamorphic imaging properties. The challenges of providing two intrinsically diverse emulation types (0.33NA isomorphic and 0.55 anamorphic) in one single platform are described together with the solutions which were implemented and tested.
High-transmission EUV pellicles supporting >400W source powervan de Kerkhof, Mark; Klein, Alexander; Vermeulen, Paul; van der Woord, Ties; Donmez, Inci; Salmaso, Guido; Maas, Raymond
doi: 10.1117/12.2614262pmid: N/A
EUV lithography has been adopted worldwide for High-Volume Manufacturing (HVM) of sub-10nm node semiconductors. To support HVM, EUV pellicles were introduced by ASML in 2016, and more recently, pellicles made from novel materials were developed to offer higher transmission and support higher source powers. In this paper, we will give an overview of current EUV pellicles. Also, we will report on our continuing research to optimize EUV pellicles to transmissions of above 90%, and supporting EUV source powers of above 400W. Key performance indicators of such novel pellicles will be presented, showing the promise of these materials to support upcoming lithography nodes.
Investigation of low-n mask in 0.33 NA EUV single patterning at pitch 28nm metal designXu, Dongbo; Gillijns, Werner; Tan, Ling Ee; Philipsen, Vicky; Kim, Ryoung-Han
doi: 10.1117/12.2614197pmid: N/A
Extending 0.33NA EUV single patterning to 28nm pitch becomes very challenging in terms of stochastic defectivity, which demands high contrast lithographic images. The low-n attenuated phase-shift mask (attPSM) can provide superior solutions for individual pitches by mitigating mask three-dimensional effects. The simulation and experiment results have shown substantial imaging improvements: higher depth of focus at similar normalized image log slope and smaller telecentricity error values than the best binary mask configuration. In this paper, the exploration of low-n attPSM patterning opportunity for pitch 28nm metal design is investigated. The lithographic performance of the low-n attPSM is compared to the standard binary Ta-based absorber mask. As well, the impact of mask tonality (bright-field vs. dark-field) on the pattern fidelity and process window is evaluated both by simulations and experiments.
Evaluation of Ta-Co alloys as novel high-k EUV mask absorberThakare, Devesh; Wu, Meiyi; Opsomer, Karl; Detavernier, Christophe; Naujok, Philipp; Saadeh, Qais; Soltwisch, Victor; Delabie, Annelies; Philipsen, Vicky
doi: 10.1117/12.2614235pmid: N/A
An alternate mask absorber is a generally applicable approach as a mitigation strategy for Mask 3-D effects (M3D) observed in EUV lithography. It is also an efficient solution in a production-worthy environment compared to multilayer modification or Source Mask Optimization (SMO) techniques. Absorbers with a high EUV extinction coefficient k allow for lower Best Focus Variation (BFV) through pitch and reduced Telecentricity Errors (TCE). This study evaluates Ta-Co alloys as potential high-k mask absorbers. It includes an experimental study of film morphology, surface composition, and stability of Ta-Co alloys as well as a theoretical investigation of the imaging performance. The optical constants were determined from EUV angle-dependent reflectivity measurements for three selected compositions, viz. TaCo, Ta2Co, and TaCo3. The Ta-Co alloys exhibit a higher EUV extinction coefficient k compared to the currently used TaBN absorber. TaCo and Ta2Co demonstrated smooth surfaces, were stable in a hydrogen environment, and in mask cleaning solutions. These qualified compositions of Ta-Co alloys were selected for aerial image simulations and compared with a TaBN absorber. The optimized absorber thickness for Ta-Co alloy absorbers is based upon NILS enhancement, Threshold to Size (TtS) and balancing of diffraction order amplitudes. A 10 nm alternate line-space pattern with a pitch of 20 nm and 14 nm square contact holes with a pitch of 28 nm were considered for the simulation study using High NA 0.55 EUV lithography process settings. The through pitch imaging performance was evaluated using NILS, TCE and BFV as metrics. Ta-Co alloys allow for a reduction in M3D effects at smaller absorber thickness compared to a 60 nm TaBN absorber.
Optimal thickness of phase shift mask considering phase and reflectance in high NA EUV contact-hole patternPark, Jang-Gun; Kim, Min-Woo; Kang, Ji-Won; Ko, Hee-Chang; Lee, Jun-Hyung; Choi, Won-Young; Oh, Hye-Keun
doi: 10.1117/12.2613984pmid: N/A
For finer linewidth patterning, 0.55 numerical aperture (NA) should be used instead of the existing 0.33 NA. In 0.55 NA extreme ultraviolet lithography (EUVL), to alleviate the mask 3D effect and stochastic noise, which is stronger, it is necessary to develop an optimal phase shift mask (PSM) and multilayer mask for high NA. Mask structure is used PSM with composed of Ru-alloy/TaBO and multilayer composed of ruthenium (Ru)/silicon (Si), which is expected to be effective in mitigating mask 3D effect and improving imaging performance. The absorber reflectance was checked which is changed by variables such as pattern existence, target CD, and pitch ratio. In addition, by examining the relationship between the change in absorber reflectance and normalized image log slope (NILS), it was determined whether the mask structure for high NA was changed by the target pattern changes.
EUV low-n attenuated phase-shift mask on random logic via single patterning at pitch 36nmTan, Ling Ee; Gillijns, Werner; Lee, Jae Uk; Xu, Dongbo; van de Kerkhove, Jeroen; Philipsen, Vicky; Kim, Ryoung-Han
doi: 10.1117/12.2614000pmid: N/A
Imec N3 logic design rules define a minimum via pitch of 36nm for a double patterning process. Enabling this pitch is crucial in terms of process time and number of masks involved. One method for extending 0.33 NA EUV is using advanced mask materials. Studies have shown that a low-n attenuated phase-shift mask (PSM) can improve EUV imaging performance, reduce mask 3D effects and improve optical contrast compared to the reference Ta-based mask. [1-3] In this paper, the impact of mask stack - Ta-based (binary or BIM) and low-n (PSM) - and mask tone - dark field (DF) vs. bright field (BF) - on a random logic Via layer will be evaluated. To pattern contact holes, we use negative tone development (NTD) metal-oxide resist process using the BF mask and positive tone development (PTD) chemically amplified resist process using the DF mask. Source mask optimization (SMO) was performed with and without subresolution assist feature (SRAF) as a resolution enhancement technology (RET). Optical proximity correction (OPC) was carried out on design clips using respective sources and mask rules at different mask tone. We show the optimum choice for this layer and present our recommendation based on current OPC simulations as well as some preliminary wafer data.
On-scanner high-spatial-frequency overlay control using a distortion manipulatorKlinkhamer, Friso; Smeets, Bart; Thijssen, Theo; Fahrni, Francis; de Boeij, Wim; El Kodadi, Mohamed; Pollak, Thilo; Emer, Wolfgang
doi: 10.1117/12.2614031pmid: N/A
As overlay tolerances tighten node-over-node, the measurement and control of overlay has progressed from the low (spatial) frequent domain toward higher spatial frequencies. At present up to 3rd order in the (non-scanning) slit direction can be addressed on high end systems. With the introduction of an advanced distortion-manipulator on an ArFi immersion scanners a significant improvement in the spatial frequency of overlay control can be achieved. This actuator will now enable at least up to 9th order lens distortion manipulation and control in the (non-scanning) slit direction, with future extendibility to on-the-fly adjustments while scanning. The manipulator setup and distortion control is fully incorporated in the scanner software and allows for lens fingerprint optimization, better dynamic lens heating control, and scanner stability control to maintain overlay performance over time. Also an external scanner overlay optimization interface is made available that enables machine-to-machine matching within the immersion platform as well as for cross-matching to the EUV platform. Via this interface also high spatial-frequent process corrections can be send to the scanner. In this paper, we will show the capability of the scanner-integrated distortion manipulator on abovementioned aspects using on-scanner aberration metrology, and in-resist distortion and overlay metrology.