Theory

Dorp, Willem F. van

doi:10.1016/b978-0-08-100354-1.00003-x

Cited by 13 publications

(3 citation statements)

References 40 publications

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“…Once EUV light is irradiated on the EUV photoresist, it excites electron-hole pair in resist polymers and presumably 80eV energies of photoelectrons cause subsequent ionization events, while losing further energy through its energy loss cascade (also called as thermalization). The scattered/emitted electrons with excess energy lose their energy through the various interaction with surrounding molecules such as ionization, plasmonic damping, electron attachment, excitons, intra/inter-molecular vibrations, and phonons as shown in figure 1 [1,2,4,9,10]. Charged radical generated during ionization process react with a nearby unexposed polymer unit, creating a neutral radical and a cationic polymer group.…”

Section: Electron Induced Chemistry and Its Impact On Electron Beam M...mentioning

confidence: 99%

“…Utilizing the 1st CD results from figure 4, we constructed a plot as a function of dose, depicted in figure 5, which we have termed the 'bursting method' [23]. As noted in previous research, the bursting method proves advantageous for focusing on the shrinkage phenomena itself, largely due to minimal interaction with the internal/external environment and rare occurrences of time-dependent effects, such as the electron cascading effect or electron transient state [9]. Furthermore, the bursting method adheres to the fundamental assumptions of the exponential decay function, derived from a differential equation based on several assumptions (for instance, "resist density remains unchanged during exposure to the e-beam", "unexposed photoresist shrinks by a constant percentage α" and so on).…”

Section: Car Type Amentioning

confidence: 99%

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The importance of less damaged and surface sensitive metrology to identify true EUV process monitoring

Lim,

Jang,

Choi

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

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The adoption of EUV technology in DRAM fabrication is primarily driven by the pursuit of higher device densities, improved performance, and increased energy efficiency. EUV's shorter wavelength (13.5 nm) enables enhanced resolution and finer patterning, enabling the production of smaller memory cells with reduced feature sizes. As the target patterning size is becoming sub-10nm, line edge/width roughness (LER/LWR) is the centerpiece in controlling uniformity of pattern going through the lithography process. Accordingly, it is essential to figure out the dedicated CDSEM metrology method for EUV step without any image quality degradation, charging issue, and e-beam damage that can hinder accurate diagnosis of the real process status. Empirically, it is highly difficult to predict the best metrology condition that fits to the specific resist material, dimension, and geometry due to complex stochastic effect caused by secondary electron inside photoresist (PR) material. Here we represent experimental results of PR damage caused by electron beam irradiation with different landing energy for both line and space (LS) pattern and contact hole (CH) pattern. The results enabled us to define the effect of the landing energy and geometry of pattern on the critical dimension (CD) and roughness. We examined electron irradiation induced damage by comparing etch bias of fresh location and e-beam exposed location on etch process step to fully understand shrinkage and deformation behavior. For the roughness measurement of CH pattern, we adopted new metric which enables us to quantify contact edge roughness and shape of contact. Utilizing various metrics, it was possible to observe damage on the process, which was not observed only by CD changes, and it was confirmed that the primary beam with low landing energy could be used to not only reduce damage but also enhance surface sensitivity of metrology without bias which is crucial for stochastic effect monitoring on the EUV process.

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Section: Electron Induced Chemistry and Its Impact On Electron Beam M...mentioning

confidence: 99%

Section: Car Type Amentioning

confidence: 99%

The importance of less damaged and surface sensitive metrology to identify true EUV process monitoring

Lim,

Jang,

Choi

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

View full text Add to dashboard Cite

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“…The initial ionization is caused by the Coulomb interaction between the valence electron in the molecule and the fast-passing electron from TEM (which can have an energy ranging from a few thousand eV to millions of eV). This process is rather like a light absorption process, with the same oscillator strength [20][21][22][23] . A bound valence electron can absorb energy from a passing beam electron, be pumped out of the molecule, and be left with a molecule with a deep hole.…”

Section: Introductionmentioning

confidence: 99%

The cage effect of electron beam irradiation damage in cryo-electron microscopy

Li,

Kang,

Dai

et al. 2024

Preprint

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Electron beam irradiation can cause damage to biological and organic samples, as determined via transmission electron microscopy (TEM). Cryo-electron microscopy (cryo-EM) significantly reduces such damage by quickly freezing the environmental water around organic molecules. However, there are multiple hypotheses about the mechanism of cryo-protection in cryo-EM. A lower temperature can cause less molecular dissociation in the first stage, or frozen water can have a “cage” effect by preventing the dissociated fragments from flying away. In this work, we used real-time time-dependent density functional theory (rt-TDDFT-MD) molecular dynamic simulations to study the related dynamics. We used our newly developed natural orbital branching (NOB) algorithm to describe the molecular dissociation process after the molecule is ionized. We found that despite the difference in surrounding water molecules at different temperatures, the initial dissociation process is similar. On the other hand, the dissociated fragments will fly away at room temperature, while they will remain in the same cage when frozen water is used. Our results provide direct support for the cage effect mechanism.

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