Imaging of 32-nm &lt;inline-formula&gt;&lt;math display="inline" altimg="none" overflow="scroll"&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;:&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/inline-formula&gt; lines and spaces using 193-nm immersion interference lithography with second-generation immersion fluids to achieve a numerical aperture of 1.5 and a &lt;inline-formula&gt;&lt;math display="inline" altimg="none" overflow="scroll"&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi mathvariant="normal

Extreme ultraviolet interferometric lithography ͑EUV-IL͒ is a powerful nanopatterning technique, exploiting the interference of two beams of short-wavelength radiation ͑ Ϸ 13 nm͒ to form high-accuracy fringe patterns. Transmission diffraction gratings of appropriate period ͑40-100 nm͒ are used to form the beams; the substrate is located in the region of overlap to expose the photoresist material, recording 20-50 nm interference fringe patterns. Although the physics of EUV-IL is simple, its actual implementation is not and requires attention to detail in order to fully exploit the power of the technique. In order to understand the impact of realistic physical conditions on the performance of EUV-IL, we have developed a set of accurate numerical models based on the Rayleigh-Sommerfeld diffraction theory. These modeling tools are then applied to generate a complete and accurate analysis of EUV-IL, taking into account all the relevant physical processes, from finite extent of the gratings to the partial coherence of the source, and including detailed physical structure of the mask. The results are used to guide the design and implementation of EUV-IL exposure systems, down to the sub-11-nm range.

Section: Introductionmentioning

confidence: 91%

Engineering study of extreme ultraviolet interferometric lithography

Jiang

Cheng

Isoyan

et al. 2009

“…5 In a double-patterning approach with high-index methods, half pitches approaching 16 nm were anticipated with the most aggressive k1 reductions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] High-index immersion was considered as an alternative next technology until the fall of 2008, when the development of the required materials and technology was stopped by the main scanner vendors, and the focus shifted toward double patterning for 32-nm node and EUV lithography for the 22-nm node. Whereas EUV has shown the required high resolution on full wafer, its readiness to produce at acceptable cost of ownership still has to be demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Fluid-photoresist interactions and imaging in high-index immersion lithography

Tran

Hendrickx

Roey

et al. 2009

Optical immersion lithography using fluids with refractive indices greater than that of water ͑1.436͒ can enable numerical apertures of 1.55 or above for printing sub-45-nm lines. Two second-generation immersion fluid candidates, IF132 and IF169, both have indices above 1.64 and have been optimized to absorb less than 0.1 cm −1 at 193.4 nm. These fluids, although meeting the requirements of index and absorption, must also be compatible with current resists and processes to image the required fine line patterns. Results of fluid-resist interactions, with water and high-index fluids on four commercial resists, are shown. Photoacid generator ͑PAG͒ leaching measurements reveal much less leaching into both high-index fluids than into water, and in two waterimmersion dedicated resists, no leaching is detected with the high-index immersion fluids. Little resist thickness change and swelling is detected by a quartz crystal microbalance ͑QCM͒ on contact with the fluids. Resist profile and line height changes due to pre-and postexposure fluid contact varies from one resist to the next, but overall the changes are minimal. Misting defects from high-index fluid-resist contact show lower counts than for water, and imaging on an immersion interference printer produces 36-nm half-pitch lines. We find no serious impediments to the use of high-index liquids based on these results.

“…The optical properties of high-index immersion fluids, 1,2 including optical absorbance, refractive index, thermo-optic coefficient, and variation of index, are critical to their use in immersion lithography. Transparency is a key requirement for immersion fluids for four major reasons: ͑i͒ to maximize the incident light on the photoresist, ͑ii͒ to minimize photoinduced fluid degradation, ͑iii͒ to minimize the photoinduced fluid temperature increase, and ͑iv͒ to prevent transmission apodization, a variation of transmission ͑flux͒ with different illumination angles.…”

Section: Introductionmentioning

confidence: 99%

Index of refraction of high-index lithographic immersion fluids and its variability

Yang

Kaplan

French

et al. 2009

We have developed a number of second-generation highindex candidate immersion fluids that exceed the 1.6 refractive index requirement for immersion lithography at 193 nm to replace the water used in first-generation immersion systems. To understand the behavior and performance of different fluid classes, we use spectral index measurements, based on the prism minimum deviation method, to characterize the index dispersion. In addition to fluid absorbance and index requirements, the temperature coefficient of the refractive index is a key parameter. We have used a laser-based Hilger-Chance refractometer system to determine the thermo-optic coefficient ͑dn /dT͒ by measuring the index change versus temperature at two different laser wavelengths, 632.8 and 193.4 nm. Also, we determined the batch-to-batch ͑within a 6-month period͒, before and after irradiation ͑at 193.4 nm͒, before and after air exposure, and before and after resist exposure ͑image printing test͒ variations of index and ⌬n / ⌬. The optical properties of these second-generation immersion fluids mostly compare favorably to water; the ratio of index of refraction at 193.4 nm is 1.644/ 1.437, the dispersion from d-line ͑⌬n 193-d ͒ is 0.160 versus 0.103 and dn /dT at 193.4 is −550ϫ 10 −6 / K vs. −93ϫ 10 −6 / K, respectively.