Deposition of Thin Copper Films Using High-Temperature Plasma Flows on the Surface of Fe, V, and Ti Metals

This paper represents the comparison results of experimental observations and theoretical calculations for splashing in deposition of Copper and Graphite thin films. These films were deposited by Pulsed Laser Deposition (PLD) technique. A Q-Switched Nd:YAG nano-second laser with 1.1 MW power. Thin films and Target surface morphology were studied under the Scanning Electron Microscope (SEM) Splashing was observed only in the copper thin films but not in graphite thin film. Theoretical models also shows the splashing only in copper, not in graphite at 1012 W/cm2 intensity of laser radiation. Because skin depth for copper (of the order of nm) smaller than that of graphite (of the order of μm) for IR radiation. Skin depth is directly related with splashing threshold intensity. Splashing produced that nonuniformity in thin films which reduced application of thin films especially in nano-electronics and smart materials.

An efficient strategy to detect latent fingermarks on metallic surfaces

Thermal effects during the deposition of thin silver, gold and copper films and their influence on internal stress measurements

Metallization plays a key role in the production process of integrated devices. Recently, copper (Cu) has been proposed as an alternative material to aluminum to address the need for metallic thin films with low resistivity and high electromigration resistance. 1 As a consequence, great attention has been paid to electrochemical processes, which enable the deposition of metallic copper at low temperatures with low costs. Copper electroless deposition has been shown to selectively plate silicon (Si) substrates and structures with high aspect ratios and large structural heights. 2,3 However, this method requires a pretreatment to activate the surface. Selectivity is achieved only to the extent that the activating treatment can be made selectively. In addition, many studies have also been carried out on the galvanic deposition of copper from fluoride containing solutions.4-11 In contrast to electroless deposition, galvanic displacement deposition requires no prior activation of the surface and is truly selective to silicon surfaces. Thus, it provides an attractive deposition method for copper interconnects or seed layers for subsequent metallization.4 Galvanic displacement is also a promising avenue for the integration of metals in micromechanical devices, due to its conformal nature and high substrate selectivity. Despite these attractive features, a crucial issue in the aforementioned processes is the lack of adhesion of copper to the Si substrate, which may severely constrain their application. 12 In particular, copper films deposited by galvanic displacement fail the qualitative Scotch tape test. In this paper, we report a process for the galvanic deposition of copper onto silicon from fluoride-containing solutions. Thin copper films with reflective and smooth surfaces and excellent adhesion to silicon are obtained. Results on plating of microelectromechanical systems (MEMS) after release are also presented. Polycrystalline silicon and single crystalline Si(100) and Si(111), p- or n-type, and analytical grade chemicals were used. Samples were ultrasonicated in acetone and, after drying with nitrogen flux, etched in concentrated hydrofluoric acid for 10 min. The hydrogenterminated surfaces thus obtained were rinsed, dried, and immersed in the plating solution. The following additives were used to prepare the aqueous solution: ammonium fluoride (NH 4 F 40%) 50 vol %, copper sulfate (CuSO 4 ·5H 2 O) 0.01 M, ascorbic acid (C 6 H 8 O 6 ) 0.01 M, sodium potassium tartrate (KNaC 4 H 4 O 6 ·4H 2 O) 0.005 M, and methanol 30 vol % (percentages are referred to the final solution volume).13 The pH of the solution was 7.5. Room temperature (25°C) and gentle agitation of samples were used. Samples were finally rinsed in deionized water and dried with nitrogen flux. The adhesion of the copper film to the substrate is strongly related to the presence of ascorbic acid in solution. The absence of the acid results in the formation of a copper film which fails the standard scotch tape test. Because we have observed a similar effect when ascorbic acid was substituted with fumaric acid, and both acids are

Palladium-free electroless deposition of pure copper film on glass substrate using hydrazine as reducing agent

Recently, Prussian blue analogues (PBAs) have been reported to exhibit a low voltage charge/discharge behavior with high capacity (300–545 mAh/g) in lithium-ion secondary batteries (LIBs) [...]

Stress development during evaporation of Cu and Ag on silicon

INTRODUCTION Copper interconnects are typically grown electrochemically as electrodeposition provides a means of depositing large amounts of material over complex geometries and is easily scalable. However, electrodeposition generally results in film microstructures that adversely affect resistivity and electromigration properties. Electromigration rates increase due to surfaces and grain boundaries, and this problem may worsen as smaller device scales lead to larger surface area to volume ratios. Chemical additives are typically used in electrolytes in order to mitigate these problems. Several additives often must be used to manufacture a high quality film, and the relative concentrations of additives can have significant impact on the microstructure of the film. Unfortunately these additives are poorly understood, and their effects are complex and empirically derived, which slows improvements in electrodeposition processes that rely on these additives. Mediating electrochemical deposition with under potentially deposited (UPD) monolayers of another elemental metal provides a controllable means of affecting the microstructure of the deposited film. The technique requires only one additive to the deposition solution, the mediating metal. This mediator must meet only a few characteristics. The mediating element must be less noble than, exhibit under potential deposition on, and not alloy with the deposited metal. The technique has been previously demonstrated for silver deposition on a single crystal gold substrate. [1,2] In this study, we extend the process to electrodeposition of silver and copper on industrially relevant polycrystalline substrates. RESULTS AND DISCUSSION We investigated UPD mediated electrodeposition of silver and copper films on polycrystalline substrates using lead as the mediating element. We varied the deposition potential to change the coverage of the UPD metal during electrodeposition, and this change in coverage caused a change in the growth mechanism of the depositing film. Silver films were deposited on polycrystalline gold films from 0.1M perchloric acid, 0.01M lead perchlorate and 0.5 mM silver perchlorate solutions. Copper films were deposited on Si substrates with polycrystalline copper seed films from 0.01M lead perchlorate and 0.01M copper perchlorate solutions. The copper films were deposited on silicon substrates as blanket films and patterned lines. We present resistivity data that demonstrate improvement over unmediated growth. In situ stress measurements of the growing films indicate UPD deposition significantly reduces the intrinsic stresses of deposited films. Atomic force microscopy images of the films are presented to show the effects of UPD on growth mechanism, surface roughness and grain sizes. We present Rutherford backscattering data to show the purity of the deposited films. Finally, we report the filling characteristics of UPD mediated deposition of Cu films on patterned Si substrates. Based on experimental results, we discuss how mediated deposition can be applied to improve the quality of electrodeposited copper for interconnect applications to improve electrical resistivity. We also discuss how this deposition technique might be applied to other film/substrate systems to tailor resistivities, intrinsic stresses, and microstructures of electrodeposited films. We also propose that the demonstrated correlation between intrinsic film stress, grain size and resistivities might be used for qualitative characterization of deposited films. The authors gratefully acknowledge materials support from Dr. Qiang Huang of IBM T. J. Watson Research Center. The authors gratefully acknowledge the support of NSF Award Number 1309849. 1. K. Sieradzki, S.R. Brankovic, and N. Dimitrov, Electrochemical Defect-Mediated Thin-Film Growth, Science, Vol. 284, pp. 138-141 (1999). 2. S.R. Brankovic, N. Dimitrov, K. Sieradzki, Surfactant Mediated Electrochemical Deposition of Ag on Au(111), J. Electrochem. Soc., Vol. 2, pp. 443-445 (1999). Figure 1

The electrical resistivity of as deposited polycrystalline copper thin films as a function of varying the process parameters has been investigated. Trying to minimize the resistivity of the copper thin films is important in the semiconductor industry, due to the fact that low resistivity copper can be employed to great advantage for new metallization schemes in advanced ultralarge scale integrated circuits. This paper presents the optimum choice of parameters that are necessary to achieve low resistivities of the thin films in reproducible experiments. All the depositions were performed using an unbalanced d.c. planar magnetron sputtering source (consisting of a circular copper target (98% purity, 0.01% Fe, 0.005% Ni, 0.005% Si) with a diameter of 100mm fitted with two electromagnets). The copper thin films were deposited onto glass substrates with argon being used as the sputtering gas. The resistivity was studied as a function of the pressure of the sputtering gas, the substrate bias, the substrate to target distance, the magnetron power, and the substrate temperature. It was found that depositions producing thin films with a resistivity of that approaching the bulk material (1.7×10−8Ωm) were obtained if the sputtering gas pressure was below 0.2 Pa. The effect of the substrate bias was insignificant at these pressures. The crystallographic structure of the copper thin films, determined by X-ray diffraction, is also reported.

Stress development during thin film growth and its modification under ion irradiation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA ring-disk electrode study of the deposition and stripping of thin copper films at platinum in sulfuric acidG. W. Tindall and Stanley. BruckensteinCite this: Anal. Chem. 1968, 40, 11, 1637–1640Publication Date (Print):September 1, 1968Publication History Published online1 May 2002Published inissue 1 September 1968https://doi.org/10.1021/ac60267a014RIGHTS & PERMISSIONSArticle Views145Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (425 KB) Get e-Alerts Get e-Alerts

The low-temperature deposition of thin-film materials from molecular transition-metal precursors is an area of rapidly growing interest. We now describe the deposition of copper-containing films from copper(I) tert-butoxide tetramer, (Cu(O-t-Bu)){sub 4}, which was chosen because it is one of the more volatile molecular derivatives of copper known. These results are related to efforts directed toward the chemical vapor deposition of thin films of the new copper oxide based high-temperature superconductors.

To simulate the aerodynamic heating environment for a hypervelocity vehicle, various ground test facilities have been developed and constructed. An arc-heated wind tunnel is one of these facilities and features long operational time; thus the arc-heated wind tunnel has been used mainly for the development and evaluation of a thermal protection system for space transportation systems. Thus generated plasma flows can be employed for the experiments of aerodynamic heating and heat protection systems but also to reveal the physical phenomenon across a shock wave in a high-temperature plasma flow. In this chapter, a 20 kW-class arc-heated wind tunnel operated at Department of Aeronautics and Astronautics, Kyushu University is depicted and shock wave experiments in an arc-heated high-temperature flow are discussed.

Demand for the development of deposition strategies of well-defined metal thin films with good chemical and physical characteristics has been rapidly growing in the field of various electronics applications. For example, copper electro- or electroless deposition has been widely utilized and investigated in microelectronics industry due to its low electrical resistivity and high electromigration resistance, as compared with aluminum. The conventional plating bath for electro- or electrolless copper deposition involves various chemical reagents such as deposition promoter (or inhibiter), brightening and smoothing agent, etc. These additives, typically organic molecules, sometimes cause mechanical problems due to inclusion of such additives during deposition process, and the discharge from the deposition bath can be a serious environmental issue. Therefore, the development of a facile process that enables additive-free deposition of metallic thin films as well as low environmental toxicity is an important challenge for the fabrication of microelectronic elements. In order to sustain the demand for generating multichip packaging systems for future electronic devices, it would be exceedingly useful to develop novel electrochemical deposition strategy with high-throughput capability that would allow stability of electrochemical reaction at higher deposition rate from plating bath without organic additives. In this context, direct metal deposition processes though ion conducting films have been investigated, such as the fabrication of metallic patterns on polymer substrates using ion-doped precursor films. A variety of direct deposition techniques have been introduced by several groups, including ours,1,2) based on photoinduced chemistry, thermal treatment, and selective chemical reduction for polyimide and other functional polymers. We have also reported a chemical metallization strategy that utilizes electrochemical constructive lithography with post lift-off process, which enables the fabrication of metal patterns on the polyimide substrate.3) The use of ion-doped precursors has triggered the development of new concept for electrochemical deposition. Herein we report for the first time that metallic thin films can be deposited through polyelectrolyte thin layers placed on the cathode electrode by the diffusion of metallic ions from the interior of polyelectrolyte, which is essentially different to conventional solution-phase electrodeposition processes (Fig. 1). By taking advantage of the cation-exchangeable nature of polyelectrolyte layers used for creation of solid interface, we demonstrate in this study how it is possible to merge the electrochemical deposition at cathode-polyelectrolyte interface and diffusion of cations through polyelectrolytes for development of novel solid electrodeposition (SED) process. As a proof of concept study, we herein present the successful electrochemical deposition of copper and nickel thin films at the interface between an electrode and ion-doped polyelectrolyte layers from the baths containing only metal salts (without any additives). The effect of cation concentration, temperature, and electrochemical deposition conditions on the deposition rate, growth process and morphology of the films has been investigated. Several electrochemical, microscopic and quantitative analysis revealed that the metallic films have been successfully deposited at the cathode-polyelectrolyte interface through ion exchange reaction in the polyelectrolyte layers, the deposition rate of which are determined by ion exchange rate of cations. This strategy offers an opportunity to translate solution-phase electrochemical deposition into a high-throughput, cost-effective, environmentally-friendly process for the fabrication of metal thin films on substrates. 1) Matsumura, Y. Enomoto, T. Tsuruoka, K. Akamatsu, H. Nawafune, Langmuir, 26, 12448-12454 (2010). 2) S. Ikeda, H. Yanagimoto, K. Akamatsu, H. Nawafune, Adv. Funct. Mater., 17, 889-897 (2007). 3) K. Akamatsu, Y. Fukumoto, T. Taniyama, T. Tsuruoka, H. Yanagimoto, H. Nawafune, Langmuir, 27, 11761-11766 (2011). Figure 1

Deposition of thin and conformal copper films has been examined using atomic layer deposition as possible seed layers for subsequent electrodeposition. For this investigation, the copper films were deposited on glass plates as well as on , , and films on silicon wafers. Typical resistivities of these films ranged from for thick copper films to for thick films. The adhesion of the copper films deposited on and at was excellent. These films were highly conformal over high aspect ratio trenches. ©2000 The Electrochemical Society