Optimizing the Smoothness and Thickness Uniformity of Thin-Film Parylene-N Vapor-Deposited Coatings for Inertial Confinement Fusion Experiments

The metal films are widely used in the Inertial Confinement Fusion (ICF) experiments to obtain the radiation opacity, and the accuracy of the measuring results mainly depends on the accuracy of the film thickness and thickness uniformity. The traditional used measuring methods all have various disadvantages, the optical method and stylus method cannot provide mass thickness which reflects the internal density distribution of the films, and the weighing method cannot provide the uniformity of the thickness distribution. This paper describes a new method which combines the α-particle energy loss (AEL) method and the successive scanning measurements to obtain the film thickness and thickness uniformity. The measuring system was partly installed in the vacuum chamber, and the relationship of chamber pressure and energy loss caused by the residual air in the vacuum chamber was studied for the source-to-detector distance ranging from 1 to 5 cm. The results show that the chamber pressure should be less than 10 Pa for the present measuring system. In the process of measurement, the energy spectrum of α-particles transmitted through each different measuring point were obtained, and then recorded automatically by a self-developed multi-channel analysis software. At the same time, the central channel numbers of the spectrum (CH) were also saved in a text form document. In order to realize the automation of data processing and represent the thickness uniformity visually in a graphic 3D plot, a software package was developed to convert the CH values into film thickness and thickness uniformity. The results obtained in this paper make the film thickness uniformity measurements more accurate and efficient in the ICF experiments.

Simulation of the thin-film thickness distribution for an OLED thermal evaporation process

The aim of this research is to realize high‐efficiency light‐emitting diodes (LEDs) with a 3D core‐shell GaN nanowire. This article describes the growth of 3D core‐shell GaN nanowires, the formation of indium tin oxide (ITO) around the p‐GaN outer shell of the nanowires, and the characteristics of the fabricated nanowire‐LED (NW‐LED). The structural properties of the n‐GaN core, GaInN/GaN multiquantum shell (MQS), p‐GaN outer shell, and ITO electrode are investigated by scanning electron microscopy and scanning transmission electron microscopy. In addition, the optical and electrical characteristics of the NW‐LEDs are evaluated. The findings show that the grown n‐GaN cores have a uniform height and diameter, the MQS is defect‐free with a uniform film thickness, and p‐GaN outer shells with a uniform thickness are grown on both the m‐ and c‐planes. Consequently, a NW‐LED that emits light from the entire chip area is successfully realized by depositing an ITO electrode that covers the p‐GaN outer shells with a uniform film thickness.

Superplastic forming Ti–6Al–4V titanium alloy cylinder with near uniform thickness distribution

An efficient domain decomposition method is proposed to study the free and forced vibrations of stepped conical shells (SCSs) with arbitrary number of step variations. Conical shells with uniform thickness are treated as special cases of the SCSs. Multilevel partition hierarchy, viz., SCS, shell segment and shell domain, is adopted to accommodate the computing requirement of high-order vibration modes and responses. The interface continuity constraints on common boundaries and geometrical boundaries are incorporated into the system potential functional by means of a modified variational principle and least-squares weighted residual method. Double mixed series, i.e., the Fourier series and Chebyshev orthogonal polynomials, are adopted as admissible displacement functions for each shell domain. To test the convergence, efficiency and accuracy of the present method, free and forced vibrations of uniform thickness conical shells and SCSs are examined under various combinations of classical and nonclassical boundary conditions. The numerical results obtained from the proposed method show good agreement with previously published results and those from the finite element program ANSYS. The computational advantage of the approach can be exploited to gather useful and rapid information about the effects of geometry and boundary conditions on the vibrations of the uniform and stepped conical shells.

Uniformity of film thickness on rotating planetary planar substrates

Uniformity in thickness and electronic properties of superconducting niobium titanium nitride (NbTiN) thin films is a critical issue for upscaling superconducting electronics, such as microwave kinetic inductance detectors for submillimeter wave astronomy. In this article we make an experimental comparison between the uniformity of NbTiN thin films produced by two DC magnetron sputtering systems with vastly different target sizes: the Nordiko 2000 equipped with a circular 100mm diameter target, and the Evatec LLS801 with a rectangular target of 127 mm x 444.5 mm. In addition to the films deposited staticly in both systems, we have also deposited films in the LLS801 while shuttling the substrate in front of the target, with the aim of further enhancing the uniformity. Among these three setups, the LLS801 system with substrate shuttling has yielded the highest uniformity in film thickness (+/-2%), effective resistivity (decreasing by 5% from center to edge), and superconducting critical temperature (T_c = 15.0 K - 15.3 K) over a 100 mm diameter wafer. However, the shuttling appears to increase the resistivity by almost a factor of 2 compared to static deposition. Surface SEM inspections suggest that the shuttling could have induced a different mode of microstructural film growth.

This work deals with the design of the thickness of an AZ31 alloy blank, which is a superplastic magnesium material, to manufacture a hemisphere with a uniform final thickness. The finite element technique was used for the design process. The superplastic free-forming manufacturing was simulated for a part whose initial thicknesses were made to vary through two independent design parameters to obtain a linear thickness decrease from the pole to the end of the blank to form. This is because a linear thickness decrease is easily obtained through a machining process. The optimized blank, that is, the blank with a non-constant thickness that leads to the most uniform thickness distribution of the formed product, allows the manufacturing of a hemisphere with more uniform thickness values with a reduction in forming times and in weight in comparison with that formed by a constant initial thickness blank. At the same time, experimental tests confirmed the results highlighted by the finite element technique.

With the trends toward larger wafer size and the linewidth going below 100 nm, one of the challenges is to control the resist thickness and uniformity to a tight tolerance in order to minimize the thin-film interference effect on the critical dimension. In this paper, we propose a new approach to improve resist thickness control and uniformity through the softbake process. Using an array of thickness sensors, a multizone bakeplate, and advanced control strategy, the temperature distribution of the bakeplate is manipulated in real time to reduce resist thickness nonuniformity. The bake temperature is also constrained to prevent the decomposition of a photoactive compound in the resist. We have experimentally obtained a repeatable improvement in resist thickness uniformity from wafer-to-wafer and across individual wafers. Thickness nonuniformity of less than 10 /spl Aring/ has been obtained. On average, there is 10 /spl times/ improvement in the thickness uniformity as compared to conventional softbake process.

Electroplating is widely used in industry and is an essential method, especially in the manufacture of electronic components. In general, electroplating can achieve metal coatings at relatively high deposition rate, but various device improvements have been made to suppress the variation in coating thickness. Additionally, complex processes such as resist formation and etching treatment are indispensable for obtaining wiring patterns.We have developed a new plating system that allows for metal film formation in a stamp-like manner without immersing the substrate in the plating solution. The device configuration and process are illustrated in Figure 1. By pressing a head section, which seals the plating solution and anode with a specific electrolyte membrane, on the surface of the substrate and applying current, metal ions preferentially pass through the electrolyte membrane and are deposited on the substrate surface. In this process, by placing a mask on the electrolyte membrane, direct formation of patterned film is possible without any special treatment of the substrate.This method has various advantages as well as facile formation of patterned film. Firstly, it reduces environmental impact. Since there is no need to immerse the head section in a plating bath such as a conventional electroplating, film formation can be achieved with a small amount of plating solution filled in the head. Additionally, even when the gap between the electrodes is reduced to a few millimeters, the electrolyte membrane acts as a separator, eliminating concerns about electrical short of circuits, and preventing contamination from the plating bath to the substrate surface or deposited film. For this reason, this method is attracting attention as a new plating method in accordance with the SDGs.Secondary, this method the excellent uniformity of film thickness in high-speed deposition. In general, as the film formation rate increases during electroplating, the uniformity of the thickness within the deposited surface deteriorates. However, our method utilizes the electrolyte membrane to maintain concentration of metal ions, allowing for variation in film thickness to be maintained within ±10%. Additionally, the metal ion mobility within the electrolyte membrane is extremely fast1), and since the substrate and electrolyte membrane are in close proximity, the so-called ion diffusion layer becomes thin. As a result, very high-speed electroplating is possible, with film formation exceeding 40 ASD for copper plating on through-holes.In this presentation, we will introduce the theoretical verification results of this method, the characteristics of the obtained coatings, and various examples of film formation aimed at practical component applications. Through this content, we hope to generate interest among as many people as possible and encourage the advancement of new plating technologies.1) K. Akamatsu, S. Nakano, K. Kimura, Y Takashima, T. Tsuruoka, H. Nawafune, Y. Sato, J. Murai, H. Yanagimoto, ACS Appl. Mater. Interfaces, 13, 13896-13906 (2021) Figure 1

Effect of magnetic field on the thickness uniformity of thin film deposited on inner surface

Multi-source evaporation is one of the methods to improve the thickness uniformity of thin films deposited by evaporation. In this study, a simulator for the relative thickness profile of a thin film deposited by a multi-source evaporation system was developed. Using this simulator, the relative thickness profiles of the evaporated thin films were simulated under various conditions, such as the number and arrangements of sources and source-to-substrate distance. The optimum conditions, in which the thickness uniformity is minimized, and the corresponding efficiency, were obtained. The substrate was a 5th generation substrate (dimensions of 1300 mm <TEX>${\times}$</TEX> 1100 mm). The number of sources and source-to-substrate distance were varied from 1 to 6 and 0 to the length of the major axis of the substrate (1300 mm), respectively. When the source plane, the area on which sources can be located, is limited to the substrate dimension, the minimum thickness uniformity, obtained when the number of sources is 6, was 3.3%; the corresponding efficiency was 16.6%. When the dimension of the source plane is enlarged two times, the thickness uniformity is remarkably improved while the efficiency is decreased. The minimum thickness uniformity, obtained when the number of sources is 6, was 0.5%; the corresponding efficiency was decreased to 9.1%. The expansion of the source plane brings about not only the improvement of the thickness uniformity, but also a decrement of the efficiency and an enlargement of equipment.

This paper presents a novel topology optimization formulation for shell-infill structures based on a distance regularized parametric level-set method (PLSM). In this method, the outer shell and the infill are represented by two distinct level sets of a single-level set function (LSF). In order to obtain a controllable and uniform shell thickness, a distance regularization (DR) term is introduced to formulate a weighted bi-objective function. The DR term is minimized along with the original objective, regularizing the parametric LSF close to a signed distance function. With the signed distance property, the area between the two-level sets can be contoured as the shell with a uniform thickness. Additionally, the presented formulation retains one important merit of the PLSM that new holes are able to nucleate during the optimization process. With respect to the material of the shell, the infill is filled with a weaker and lighter material with tunable parameters. Particularly, the infill can be pre-designed with isotropic microstructures. Three compliance minimization examples are provided to demonstrate the effectiveness of this formulation.

A new type of multi-site magnetron sputtering system has been researched, which has more than one workbench. Based on the operating principle of the magnetron sputtering system which with a circular plane target, a mathematical model has been developed to simulate and discuss the influencing factors on the film thickness uniformity. The results showed that when the substrates were rotating axially and eccentrically, the film thickness distribution were affected by both the target-substrate distance and the eccentricity. If the eccentricity was constant, the film thickness would become thinner when the target-substrate distance increased, and the thickness uniformity tended to be improved. If the target-substrate distance was constant, the thickness uniformity would become better when the eccentricity increased. Moreover, if the substrate rotated axially and revolved around the target simultaneously, the thickness uniformity would become better when velocity ratio of axial rotation to revolution increased. And the effect of the thickness uniformity became small gradually if the ratio increases to a certain degree. In addition, increasing the etching area properly not only could conduct the film distribution to better, and improve the substrate film thickness uniformity also. Finally, taking a series of experiments, and analyzing the experimental data, the conclusion of the study results in the paper had been verified.

Atomic layer deposition (ALD) has emerged as an essential technique, enabling the deposition of titanium nitride (TiN), which is renowned for its exceptional metal diffusion barrier properties. Improving within-wafer uniformity has become increasingly important to actively transition from lab-scale process development to wafer manufacturing. We considered the effect of gas velocity on thickness uniformity through computational fluid dynamics (CFD) simulations. Gas velocity was controlled by varying equipment design parameters, and it was confirmed that the resulting reduction in velocity improved both velocity and thickness uniformity. To validate the simulation results, an ALD reactor was experimentally performed under the same design and process conditions. The measured thickness of the deposited films confirmed an improvement in thickness uniformity, and the cause of the thickness reduction was further investigated. This study demonstrates that controlling gas velocity prov ides valuable insights into improving thickness uniformity in the ALD reactor. It confirms the effectiveness of simulations in overcoming the limitations associated with considering various process and equipment variables, which can be time-consuming and costly. Furthermore, it emphasizes the importance of integrating flow dynamic simulations with process evaluations to contribute to the advancement of semiconductor manufacturing technologies.