Showing papers on "Proximity effect (electron beam lithography) published in 2020"

Direct Color Printing with an Electron Beam.

Abstract: The direct patterning of colors using the bombardment of a focused beam of electrons onto a thin-film stack consisting of poly(methyl methacrylate) coated with a thin nickel film is demonstrated. This direct electron-beam color printing approach creates variations in the height of a Fabry-Perot (FP) cavity, resulting directly in a color print without the need for prepatterned substrates, distinct from some direct laser writing methods. Notably, the resolution of the color prints is defined by the electron beam. Height measurements with ∼5 nm accuracy through color image analysis of an electron-beam-patterned FP cavity were carried out. This technique also introduces a reflectance-based measurement of the point exposure function of a focused electron beam, aiding in rapid proximity effect corrections. In addition, the grayscale lithographic nature of this process was used to produce blazed gratings and could enable the fabrication of other 2.5D nanostructures with precise height control.

Intensity modulation based optical proximity optimization for the maskless lithography

Abstract: The undesirable optical proximity effect (OPE) that appeared in the digital micro-mirrors device (DMD) based maskless lithography directly influences the final exposure pattern and decreases the lithography quality. In this manuscript, a convenient method of intensity modulation applied for the maskless lithography is proposed to optimize such an effect. According to the pulse width modulation based image recognition of DMD, we replaced the digital binary mask with a special digital grayscale mask to modulate the UV intensity distribution to be closer to the expectation in a way of point-by-point modification. The exposure result applying the grayscale mask has a better consistency with the design pattern than that for the case in which the original binary mask is used. The effectiveness of this method was analyzed by the image subtraction technique. Experimental data revealed that the matching rate between the exposure pattern and the mask pattern has been improved from 78% to 91%. Besides, more experiments have been conducted to verify the validity of this method for the optical proximity optimization and its potential in the high-fidelity DMD based maskless lithography.

Focusing on nanoparticles based photomultiplier in n-CARs

Abstract: To meet the International Roadmap for Device and Systems (IRDS), the development of an advanced lithography process for next-generation (NG) technology node is a vital and challenging task, as we are reaching to its physical limits. In the progress of high volume manufacturing (HVM) at sub-12 nm node, it is very important that resist materials should possess low line edge roughness (LER) and high sensitivity (E0) using extreme ultraviolet (EUV) and its analogous exposure systems. Apart from standard chemically amplified resist (CAR), acid-free non-CAR has been studied immensely as a potential candidate for NG patterning. To achieve sub-12 nm patterns, a complete study for newly developed n-CAR is required to make sure that developed resist formulation is performing optimally. Aside from the n-CARs, we adopted a novel patterning approach using He+ ion beam lithography with less proximity effect. Here we present the metallic nanoparticle photo-multiplier (high optical density materials for λ ~13.5 nm) embedded with n-CAR for better photo-absorption and high-resolution pattern development. The silver (Ag- OD 12 w.r.t Carbon) nanoparticles (NPs) with ~2 nm regime were embedded into MAPDST homo-polymer ((4-(methacryloyloxy)phenyl) dimethylsulfonium trifluoromethanesulfonate). To investigate the high-resolution patterning synthesized photoresist was exposed to e-beam (Ee) and Helium ion (EHe) beam lithography. The patterned samples were developed in aqueous solution and revealed the negative tone with the sensitivity of 172 μC/cm2 and 50.4 μC/cm2 for Ee and EHe respectively. The MAPDST-Ag resist found stable for more than 1 year, which clearly suggests that there is no sign of Ag-NPs agglomeration in the formulation. Thence, evidently, prove the considerable shelf life of developed resist formulation and can be used in NG semiconductor device HVM and other electronic device applications.

Electron beam proximity effect correction method based on neural network

Abstract: The invention belongs to the field of computational lithography, and discloses an electron beam proximity effect correction method based on a neural network. According to the invention, firstly, any proximity effect dose correction method is adopted to perform dose correction on a designed training layout, neural network parameters are adjusted, neural network training is performed on the traininglayout according to a specified input mode, a self-adaptive neural network is obtained through training, and finally any exposure layout correction dose is predicted according to the specified inputmode. According to the invention, the electron beam proximity effect correction based on the neural network is realized, problems in the proximity effect correction calculation of electron beam exposure is solved, the correction calculation efficiency is greatly improved on the basis of ensuring high-precision correction, and the method has the characteristics of high calculation precision, high calculation efficiency and the like.

Organic Resist Contrast Determination in Ion Beam Lithography

Abstract: The feature of the promising tool of lithographic nanostructuring based on selective exposure of polymer resist by ion beam is very compact (of about tens of nanometers) beam interaction volume. Herewith the main part of beam energy is deposited in the resist and is spent to its modification. It causes the set of advantages specific for this method: sub-10 nanometer resolution achievable, very high energy efficiency and almost complete absence of proximity effect. But also due to this feature absorbed doze essentially inhomogeneous in resist and the dissolution rate is strongly dependent on depth. So the common procedure of resist contrast determination cannot be applied anymore. In the present work a new method for resist contrast determination considering the relation between dissolution rate and deposited energy density is suggested and realized. By using it for PMMA resist irradiated by 30 keV Ga+ ion beam the value of contrast was determined to be 3.1 and ions energy length was estimated to be 42 nm.