Polarization effects in immersion lithography

Adam, Kostas; Maurer, Wilhelm

doi:10.1117/12.534322

Cited by 10 publications

(6 citation statements)

References 9 publications

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“…In a similar vein, state-of-the-art OPC tools now use vector imaging models which incorporate vector effects, film stack, source map, pupil map, polarization, and a non-air ambient medium [2], [3]. This reflects a modern trend in OPC modeling methodology: move away from the "black box" modeling, to develop physically-based models, able to reliably predict CD variability under changing process conditions.…”

Section: Model Accuracymentioning

confidence: 96%

New concepts in OPC

Cobb

Granik

2004

SPIE Proceedings

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In this paper, we will discuss two new concepts to be used in model-based OPC: model-based fragmentation, and model tagging to account for long-range proximity effects. In model-based fragmentation we create an initial fragmentation consisting of small fragmentation across the design. Then, specific fragments are removed according to image criteria in order to keep only those fragmentation points which affect the aerial image the most. Optical flare and long-range etch effects are challenging because they have long interaction ranges. We describe here an edge tagging technique that binds different models to different regions on the layout enabling aberration-or density-sensitive corrections. We show application of this technique on a layout section. We discuss how to implement these techniques in practice and what impact they have on OPC speed and accuracy.

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Section: Model Accuracymentioning

confidence: 96%

New concepts in OPC

Cobb

Granik

2004

SPIE Proceedings

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“…Linear polarization is one of the most effective forms of polarization for enhancing the image contrast [7] and it is relatively simple to implement in exposure systems. The incomplete interference of the TM polarize light can severely reduce the image contrast ( Figure 8a).…”

Section: Contrast Enhancement Of Ddl/del With Polarizationmentioning

confidence: 99%

Double exposure technique for 45nm node and beyond

Hsu¹,

Park²,

Broeke³

et al. 2005

SPIE Proceedings

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The technical challenges in using F2 lithography for the 45nm node, along with the insurmountable difficulties in EUV lithography, has driven the semiconductor chipmaker into the low k 1 lithography era under the pressure of ever decreasing feature sizes. Extending lithography towards lower k 1 puts heavy demand on the resolution enhancement technique (RET), exposure tool, and the need for litho friendly design. Hyper numerical aperture (NA) exposure tools, immersion [1], and double exposure techniques (DET's) are the promising methods to extend lithography manufacturing to the 45nm node at k 1 factors below 0.3. Scattering bars (SB's) [2] have become an integral part of the lithography process as chipmakers move to production at ever lower k 1 factors. To achieve better critical dimension (CD) control, polarization is applied to enhance the image contrast in the preferential imaging orientation, which increases the risk of SB printability. The optimum SB width is approximately (0.20 ~ 0.25)*(λ/NA).[1] When the SB width becomes less than the exposure wavelength on the 4X mask, Kirchhoff's scalar theory under predicts the SB intensity. The optical weighting factor of the SB increases ( Figure 1b) and the SB's become more susceptible to printing. Meanwhile, under hyper NA condition's, the effectiveness of "sub-resolution" SB's is significantly diminished. A full-sized scattering bars (FSB) scheme becomes necessary. Double exposure methods, such as using ternary 6% attenuated PSM (attPSM) for DDL, are good imaging solutions that can reach and likely go beyond the 45nm node. Today DDL, using binary chrome masks, is capable of printing 65 nm device patterns. [3,4,5] In this work, we investigate the use of DET with 6% attPSM masks to target 45nm node device. The SB scalability and printability issues can be taken cared of by using "mutual trimming", i.e., with the combined energy from the two exposures. In this study, we share our findings of using DET to pattern a 45nm node device design with polarization and immersion. We also explore other double patterning methods which in addition to having two exposures, incorporates double coat/developing/etch processing to break the 0.25 k 1 barrier.

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“…TE polarized light is generally preferred for layouts without distinct feature orientation. On the other hand, TM and polarization in directions perpendicular to feature orientations should be subdued as much as possible [1][2][3][4].…”

Section: Introductionmentioning

confidence: 98%

Rigorous vectorial modeling for polarized illumination and projection pupil in OPC

et al. 2008

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High NA and Ultra-High NA (NA>1.0) applications for low k 1 imaging strongly demand the adoption of polarized illumination as a resolution enhancement technology since proper illumination polarization configuration can greatly improve the image contrast hence pattern printing fidelity and the effectiveness of optical proximity correction (OPC). However, current OPC/RET modeling software can only model the light source polarization of simple types, such as TE, TM, X, Y, or sector polarization with relatively simple configuration. Realistic polarized light used in scanners is more complex than the aforementioned simple ones. As a result, simulation accuracy and quality of the OPC result will be compromised by the simplification of the light source polarization modeling in the traditional approach. With ever shrinking CD error budget in the manufacturing of IC's at advanced technology nodes, more accurate and comprehensive illumination source modeling for lithography simulations and OPC/RET is needed. On the other hand, for polarized illumination to be fully effective, ideally all the components in the optical lithography system should not alter the polarization state of light during its propagation from illuminator to wafer surface. In current OPC modeling tools, it is typically assumed that the amplitude and polarization state of the light do not change as it passes through the projection lens pupil, i.e. the polarization aberration of projection lens pupil is ignored. However, in reality, the projection lens pupil of the scanner does change the amplitude and the polarization state to some extent, and ignorance of projection pupil induced polarization state and amplitude changes will cause CD errors un-tolerable at the 45nm device generation and beyond.We developed an OPC-deployable modeling approach to model arbitrarily polarized light source and arbitrarily polarized projection lens pupil. Based on polarization state vector descriptions of a general illumination source, this modeling approach unifies optical simulations of unpolarized, partially polarized, and completely polarized illuminations. The polarization aberration imposed by the projection lens pupil is modeled via Jones matrix format, and it is applicable to arbitrary polarization aberrations imposed by any components in the lithography system that can be characterized in Jones matrix format. Numerical experiments were performed to study CD impact from illumination polarization and projection lens pupil polarization aberrations, and up to several nanometers impact on optical proximity effect (OPE) was observed, which is not negligible given the extremely stringent CD error budget at 45nm node and beyond. Based on an experimentally measured Jones matrix pupil which intrinsically provides a much better approximation to the physical scanner projection pupil, we propose a more physics-centric methodology to evaluate the optical model accuracy of OPC simulator.

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Polarization effects in immersion lithography

Cited by 10 publications

References 9 publications

New concepts in OPC

New concepts in OPC

Double exposure technique for 45nm node and beyond

Rigorous vectorial modeling for polarized illumination and projection pupil in OPC

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