Simulation of shot noise effect on CD and LER of electron-beam lithography in 32nm designs

Patsis, G. P.; Τσικρικάς, Ν.; Drygiannakis, D.; Raptis, Ioannis

doi:10.1016/j.mee.2009.11.014

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…5 On the other hand, high frequency roughness can cause local variations in 15 voltage in transistors, and hence lead to variations in leakage or threshold voltages. 6,7 The origins of line edge roughness have been the subject of intense investigation, and factors such as acid diffusion, [8][9][10] shot noise [11][12][13][14] and mask roughness [15][16][17][18][19][20][21] identified as major contributors. [22][23][24][25] However, it has been suggested that the inherent heterogeneity of the photoresist may also strongly contribute to the generation of rough features upon processing.…”

Section: Introductionmentioning

confidence: 99%

“…Low-frequency roughness can potentially increase severely the failure rate of memory devices . On the other hand, high-frequency roughness can cause local variations in voltage in transistors and hence lead to variations in leakage or threshold voltages. , The origins of line edge roughness have been the subject of intense investigation and factors such as acid diffusion, − shot noise, − and mask roughness − identified as major contributors. − However, it has been suggested that the inherent heterogeneity of the photoresist may also strongly contribute to the generation of rough features upon processing. This includes heterogeneity in the distribution of photoacid generator (PAG) or other components such as base quencher and in the resist polymer itself.…”

Section: Introductionmentioning

confidence: 99%

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Terpolymerization of Styrenic Photoresist Polymers: Effect of RAFT Polymerization on the Compositional Heterogeneity

et al. 2015

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The heterogeneity of the chemical structure of photoresist polymers, both within and 1 between the polymer chains, is believed to contribute to the phenomenon of line edge roughness 2 in high-resolution lithography. The copolymerization and terpolymerization of three important photoresist monomers, 4-acetoxystyrene (AOST), styrene (Sty) and tertiary-butyl acrylate (tBA) is examined in detail in this work. In particular the effect of the use of a reversible addition fragmentation chain transfer (RAFT) agent in these reactions is reported. The pair-wise copolymerization reactivity ratios for the RAFT polymerizations are close to, but different from those measured under the same conditions but in the absence of the RAFT agent. The differences are suggested to be related to the effect of the RAFT agent on the environment of the locus of polymerization. The course of the terpolymerization reactions can be well predicted from the copolymer reactivity ratios and the classical Alfrey-Goldfinger expression, indicating that the reactions in this system conform to terminal model of reactivity. Calculations of the expected sequence distributions as a function of composition and conversion clearly demonstrate that the polymers prepared under RAFT conditions are significantly more homogeneous that their counterparts prepared using conventional free radical polymerization. The significance of these results for the performance of the RAFT terpolymers in photoresist formulations is highlighted.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Terpolymerization of Styrenic Photoresist Polymers: Effect of RAFT Polymerization on the Compositional Heterogeneity

et al. 2015

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Various papers based on Monte Carlo simulations have been reported on scattering by electron irradiation. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Our measurements of surface potentials with an electrostatic force microscope (EFM) confirmed the presence of a potential distribution of the order of several V even a few mm away from the EB exposure point. Deviations of tens of nm from the design position of the exposure point due to this potential have been reported to be serious.…”

Section: Introductionmentioning

confidence: 72%

Investigation of non-charging exposure conditions for insulating resist films in electron beam lithography

Kubo

Kojima

Kono

et al. 2021

Jpn. J. Appl. Phys.

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When the electron beam (EB) irradiates insulating films on a conducting substrate, the film charges positively or negatively, depending on the condition. The surface potential distribution is measured using an electrostatic force microscope installed in the specimen chamber of a scanning electron microscope. The multiple backscattering phenomenon of electrons between the specimen and the bottom of the objective lens electrode causes a global charging even a few millimeters away from the EB irradiation area. This charging can be suppressed by applying −5 V to the specimen. On the other hand, the charge in the irradiation area changes depending on the exposure dose. When the dose is small, it is positively charged, but when the exposure dose is large, it is negatively charged. However, as the dose increases, it becomes positive again. When the insulating film is irradiated with an EB, the charging potential disappears twice depending on the irradiation dose, and the electric potential distribution was found to be M-shaped and W-shaped. We propose a model to explain this phenomenon.

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“…The uncertainty and statistical fluctuation become significant according to the shrink of design node. There are several studies of shot noise effect on LER [9], [10]. The higher exposure dose is efficient for reduction of shot noise and LER improvement.…”

Section: Simulation Of Image Placement Errormentioning

confidence: 99%

The requirements for the future e-beam mask writer: statistical analysis of pattern accuracy

et al. 2011

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As semiconductor features shrink in size and pitch, the extreme control of CD uniformity, MTT and image placement is needed for mask fabrication with e-beam lithography. Among the many sources of CD and image placement error, the error resulting from e-beam mask writer becomes more important than before. CD and positioning error by e-beam mask writer is mainly related to the imperfection of e-beam deflection accuracy in optic system and the charging and contamination of column. To avoid these errors, the e-beam mask writer should be designed taking into account for these effects. However, the writing speed is considered for machine design with the highest priority, because the e-beam shot count is increased rapidly due to design shrink and aggressive OPC. The increment of shot count can make the pattern shift problem due to statistical issue resulting from e-beam deflection error and the total shot count in layout. And it affects the quality of CD and image placement too.In this report, the statistical approach on CD and image placement error caused by e-beam shot position error is presented. It is estimated for various writing conditions including the intrinsic e-beam positioning error of VSB writer. From the simulation study, the required e-beam shot position accuracy to avoid pattern shift problem in 22nm node and beyond is estimated taking into account for total shot count. And the required local CD uniformity is calculated for various e-beam writing conditions. The image placement error is also simulated for various conditions including e-beam writing field position error. Consequently, the requirements for the future e-beam mask writer and the writing conditions are discussed. And in terms of e-beam shot noise, LER caused by exposure dose and shot position error is studied for future e-beam mask writing for 22nm node and beyond.

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Simulation of shot noise effect on CD and LER of electron-beam lithography in 32nm designs

Cited by 10 publications

References 9 publications

Terpolymerization of Styrenic Photoresist Polymers: Effect of RAFT Polymerization on the Compositional Heterogeneity

Terpolymerization of Styrenic Photoresist Polymers: Effect of RAFT Polymerization on the Compositional Heterogeneity

Investigation of non-charging exposure conditions for insulating resist films in electron beam lithography

The requirements for the future e-beam mask writer: statistical analysis of pattern accuracy

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