Why NA is Not Relevant to Resolution in EUV Lithography

Why NA is Not Relevant to Resolution in EUV Lithography
by Fred Chen on 05-05-2024 at 8:00 am

Why NA is Not Relevant to Resolution in EUV Lithography

The latest significant development in EUV lithography technology is the arrival of High-NA systems. Theoretically, by increasing the numerical aperture, or NA, from 0.33 to 0.55, the absolute minimum half-pitch is reduced by 40%, from 10 nm to 6 nm. However, for EUV systems, we need to recognize that the EUV light (consisting … Read More


Huawei’s and SMIC’s Requirement for 5nm Production: Improving Multipatterning Productivity

Huawei’s and SMIC’s Requirement for 5nm Production: Improving Multipatterning Productivity
by Fred Chen on 04-23-2024 at 10:00 am

Self aligned blocking scheme

There has been much interest in Huawei’s and SMIC’s plans for 5nm production in the near future. Since there is no use of EUV in China, immersion DUV lithography (with a 76 nm pitch resolution) is expected to be used along with pitch quartering to achieve pitches in the 20-30 nm range expected for the 5nm and 3nm nodes [1].… Read More


Measuring Local EUV Resist Blur with Machine Learning

Measuring Local EUV Resist Blur with Machine Learning
by Fred Chen on 03-17-2024 at 10:00 am

Measuring Local EUV Resist Blur with Machine Learning

Resist blur remains a topic that is relatively unexplored in lithography. Blur has the effect of reducing the difference between the maximum and minimum doses in the local region containing the feature. Blur is particularly important for EUV lithography since EUV lithography is prone to stochastic fluctuations and also driven… Read More


Pinning Down an EUV Resist’s Resolution vs. Throughput

Pinning Down an EUV Resist’s Resolution vs. Throughput
by Fred Chen on 02-21-2024 at 8:00 am

Pinning Down an EUV Resist's Resolution

The majority of EUV production is on 5nm and 3nm node, implemented by late 2022. Metal oxide resists have not been brought into volume production yet [1,2], meaning that only organic chemically amplified resists (CARs) have been used instead until now. These resists have a typical absorption coefficient of 5/um [3,4], which means

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Application-Specific Lithography: Avoiding Stochastic Defects and Image Imbalance in 6-Track Cells

Application-Specific Lithography: Avoiding Stochastic Defects and Image Imbalance in 6-Track Cells
by Fred Chen on 02-07-2024 at 6:00 am

Application Specific Lithography

The discussion of any particular lithographic application often refers to imaging a single pitch, e.g., 30 nm pitch for a 5nm-family track metal scenario. However, it is always necessary to confirm the selected patterning techniques on the actual use case. The 7nm, 5nm, or 3nm 6-track cell has four minimum pitch tracks, flanked… Read More


Application-Specific Lithography: Sense Amplifier and Sub-Wordline Driver Metal Patterning in DRAM

Application-Specific Lithography: Sense Amplifier and Sub-Wordline Driver Metal Patterning in DRAM
by Fred Chen on 12-25-2023 at 10:00 am

Varying pitch in metal lines in DRAM periphery

On a DRAM chip, the patterning of features outside the cell array can be just as challenging as those within the array itself. While the array contains features which are the most densely packed, at least they are regularly arranged. On the other hand, outside the array, the regularity is lost, but the in the most difficult cases, … Read More


Predicting Stochastic Defectivity from Intel’s EUV Resist Electron Scattering Model

Predicting Stochastic Defectivity from Intel’s EUV Resist Electron Scattering Model
by Fred Chen on 11-22-2023 at 6:00 am

Predicting Stochastic Defectivity from Intel's EUV Resist Electron Scattering Model

The release and scattering of photoelectrons and secondary electrons in EUV resists has often been glossed over in most studies in EUV lithography, despite being a fundamental factor in the image formation. Fortunately, Intel has provided us with a laboriously simulated electron release and scattering model, using the GEANT4… Read More


The Significance of Point Spread Functions with Stochastic Behavior in Electron-Beam Lithography

The Significance of Point Spread Functions with Stochastic Behavior in Electron-Beam Lithography
by Fred Chen on 10-31-2023 at 10:00 am

Electron Beam Lithography

Electron beam lithography is commercially used to directly write submicron patterns onto advanced node masks. With the advent of EUV masks and nanometer-scale NIL (nanoimprint lithography), multi-beam writers are now being used, compensating the ultralow throughput of a single high-resolution electron beam with the use… Read More


Extension of DUV Multipatterning Toward 3nm

Extension of DUV Multipatterning Toward 3nm
by Fred Chen on 10-02-2023 at 8:00 am

Extension of DUV Multipatterning Toward 3nm

China’s recent achievement of a 7nm-class foundry node using only DUV lithography [1] raises the question of how far DUV lithography can be extended by multipatterning. A recent publication at CSTIC 2023 indicates that Chinese groups are currently looking at extension of DUV-based multipatterning to 5nm, going so far… Read More


Stochastic Model for Acid Diffusion in DUV Chemically Amplified Resists

Stochastic Model for Acid Diffusion in DUV Chemically Amplified Resists
by Fred Chen on 09-11-2023 at 8:00 am

Stochastic Model for Acid Diffusion in DUV Chemically Amplified Resists 1

Recent articles have focused much effort on studying the stochastic behavior of secondary electron exposure of EUV resists [1-4]. Here, we consider the implications of extending similar treatments to DUV lithography.

Basic Model Setup

As before, the model uses pixel-by-pixel calculations of absorbed photon dose, followed… Read More