Optimization of process condition to balance MEF and OPC for alternating PSM: control of forbidden pitches

Kim, Keeho; Choi, Yongseok; Socha, Robert; Flagello, Donis G.

doi:10.1117/12.474573

Cited by 9 publications

(6 citation statements)

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“…From the other side, as we all know there are several RET techniques [8][9][10][11][12][13][14] for low k1 case without increase NA. However each RET techniques has their own merits and demerits.…”

Section: Introductionmentioning

confidence: 98%

“…But the mask cost is not acceptable for most of IC designers and foundry companies except DRAM companies. [12][13] Scattering bar technology can help to improve semi-ISO and ISO features performance. But it still can not resolve semi-dense such as forbidden pitches issues if the scattering bar can not be insert due to mask space limitation.…”

Section: Introductionmentioning

confidence: 99%

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248nm Process Is Capable for sub 0.09 um Groundrules

Wang¹,

Guo

Tong

et al. 2011

ECS Trans.

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While the mainstream wafer production is at 0.065 and 0.045 um with 300 mm diameter wafers with ArF exposure tools systems, an idea to explore production feasibility under groundrules smaller than 0.09 um while maintain the cost advantages in KrF exposure tools systems becomes more and more popular and important to all companies including 300mm/200mm FAB. But the k1 factor for sub 0.09um with current popular KrF exposure tools will be about 0.31, which has the same level of complexity in optical proximity correction compared to 0.045 um at 0.93 NA with 193 nm exposure tools. Several RET (Resolution Enhancement Technology) techniques have been proposed for low k1 case and some good results have been achieved. However, each RET techniques has their own merits and demerits. It is still attractive to find out a solution with current KrF exposure tools, popular illumination settings and cost effective masks. In this paper, we will introduce our study for sub 0.09 um design rule with maximum 0.82NA KrF scanner tools. No special RET techniques are used and acceptable DOF, EL, MEEF, LWR and CD proximity are achieved. A novel photoresist optimization solution is both discussed.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

248nm Process Is Capable for sub 0.09 um Groundrules

Wang¹,

Guo

Tong

et al. 2011

ECS Trans.

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“…Although SRAFs are an effective method to collect high-order diffraction on the entrance pupil plane of a projection lens [5], Shi et al report that incorrect SRAF placements around a given main feature can actually degrade the process latitude of that feature. A number of previous works have proposed techniques to control forbidden pitches using optimization of optical conditions such as numerical aperture (NA) and illuminator aperture shape of OAI [6,7].…”

Section: A Related Workmentioning

confidence: 99%

Detailed placement for improved depth of focus and CD control

Gupta

Kahngt

Park

2005

Proceedings of the 2005 Conference on Asia South Pacific Design Automation - ASP-DAC '05

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Sub-resolution assist features (SRAFs) provide an absolutely essential technique for critical dimension (CD) control and process window enhancement in subwavelength lithography. However, as focus levels change during manufacturing, CDs at a given "legal" pitch can fail to achieve manufacturing tolerances required for adequate yield. Furthermore, adoption of off-axis illumination (OAI) and SRAF techniques to enhance resolution at minimum pitch worsens printability of patterns at other pitches. This paper describes a novel dynamic programming-based technique for Assist-Feature Correctness (AFCorr) in detailed placement of standard-cell designs. For benchmark designs in 130nm and 90nm technologies, AFCorr achieves improved depth of focus and substantial improvement in CD control with negligible timing, area, or CPU overhead. The advantages of AFCorr are expected to increase in future technology nodes.

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“…Typical experimental methods may carry an error as much as 10 to 20 nm. Also, as the lithographic dimension gets smaller, mask error factor (MEF) becomes larger and starts to limit CD control [5][6][7][8][9][10][11]. In this paper, we present a systematic study, which will introduce a very accurate measurement method (to 1 to 2 nm) for the resist diffusion length and a theoretical framework for the evaluation of the effect of such diffusion to the image contrast and MEF under various illumination and mask conditions for photolithography at 65 nm and 45 nm nodes.…”

Section: Introductionmentioning

confidence: 99%

Effect of the effective resist diffusion length to the photolithography at 65- and 45-nm nodes: a study with simple and accurate analytical equations

Wu¹,

Halle²,

Zhao³

2004

SPIE Proceedings

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As the current photolithography moves toward the 65 and 45 nm nodes, resist blur, which is now around 50 to 90 nm full width at half maximum (FWHM), starts to limit the printability of narrow pitches by lowering image contrast, increasing mask error factor (MEF), and changing critical dimension (CD) through pitch behavior. Since such resist blur is known to originate from acid and base diffusion, which is an important process for chemical amplification, the reduction of such blur may affect the resist performance. Therefore, knowing how much diffusion can be tolerated at any given lithographic condition is critical to the success of photolithography at the 65 and 45 nm nodes.In this paper, we present a systematic study of the effect of the resist diffusion with a series of simple and accurate analytic equations and experimental data for the 193 nm lithography. We also extend our predictions to the 193 nm immersion lithography. We first show a simple way to accurately measure the effective resist diffusion length through the regular wafer exposure method for many typical resists. We then show a method to accurately quantify the contrast reduction due to such resist diffusion for both alternating phase shifting masks (Alt-PSM) and attenuated phase shifting masks (Att-PSM). We conclude that the contrast reduction is very significant with typical 193 nm resists, which have diffusion lengths of around 30 to 40 nm. In the study, we found that the mask error factor (MEF), though dependent on the illumination condition, is a strong function of the resist diffusion length at any given illumination condition. For example, in the alt-PSM case, the MEF is almost entirely determined by the resist diffusion. In the att-PSM case, however, the MEF is only partially dependent on the resist diffusion length, about 50%. In fact, a short diffusion length of less than 20 nm will be required to extend its litho-worthiness to the 45 nm node with contrast levels comparable to the current ones. Plots of the contrast and MEF through pitch for both alt-PSM and att-PSM for various diffusion lengths under typical lithographic conditions will be presented. Experimental verification of the above analytical equations will be presented.

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Optimization of process condition to balance MEF and OPC for alternating PSM: control of forbidden pitches

Cited by 9 publications

References 0 publications

248nm Process Is Capable for sub 0.09 um Groundrules

248nm Process Is Capable for sub 0.09 um Groundrules

Detailed placement for improved depth of focus and CD control

Effect of the effective resist diffusion length to the photolithography at 65- and 45-nm nodes: a study with simple and accurate analytical equations

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