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


Modeling EUV Stochastic Defects with Secondary Electron Blur

Modeling EUV Stochastic Defects with Secondary Electron Blur
by Fred Chen on 08-30-2023 at 8:00 am

Modeling EUV Stochastic Defects With Secondary Electron Blur

Extreme ultraviolet (EUV) lithography is often represented as benefiting from the 13.5 nm wavelength (actually it is a range of wavelengths, mostly ~13.2-13.8 nm), when actually it works through the action of secondary electrons, electrons released by photoelectrons which are themselves released from ionization by absorbed… Read More


Assessing EUV Wafer Output: 2019-2022

Assessing EUV Wafer Output: 2019-2022
by Fred Chen on 06-26-2023 at 6:00 am

Assessing EUV Wafer Output 2019 2022

At the 2023 SPIE Advanced Lithography and Patterning conference, ASML presented an update on its EUV lithography systems in the field [1]. The EUV wafer exposure output was presented and is shown below in table form:

From this information, we can attempt to extract and assess the EUV wafer output per quarter. First, since there … Read More


Horizontal, Vertical, and Slanted Line Shadowing Across Slit in Low-NA and High-NA EUV Lithography Systems

Horizontal, Vertical, and Slanted Line Shadowing Across Slit in Low-NA and High-NA EUV Lithography Systems
by Fred Chen on 01-11-2022 at 6:00 am

EUV shadowing across slit

EUV lithography systems continue to be the source of much hope for continuing the pace of increasing device density on wafers per Moore’s Law. Recently, although EUV systems were originally supposed to help the industry avoid much multipatterning, it has not turned out to be the case [1,2]. The main surprise has been the

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Revisiting EUV Lithography: Post-Blur Stochastic Distributions

Revisiting EUV Lithography: Post-Blur Stochastic Distributions
by Fred Chen on 11-14-2021 at 10:00 am

Revisiting EUV Lithography Post Blur Stochastic Distributions

In previous articles, I had looked at EUV stochastic behavior [1-2], primarily in terms of the low photon density resulting in shot noise, described by the Poisson distribution [3]. The role of blur to help combat the randomness of EUV photon absorption and secondary electron generation and migration was also recently considered… Read More