Young's modulus of electroplated Ni thin film for MEMS applications

The Young's modulus of an electroplated nickel (Ni) thin film suitable for microelectromechanical applications has been investigated as a function of process variables: the plating temperature and current density. It was found that the Young's modulus is approximately 205 GPa at plating temperatures less than 60 °C, close to that of bulk Ni, but drastically drops to approximately 100 GPa at 80 °C. The inclusion of ammonium and sulphate ions by hydrolysis is believed to be responsible for the sharp drop. The Young's modulus of 205 GPa is for a Ni film plated at J=2 mA/cm² and it decreases to 85 GPa as the plating current density is increased to 30 mA/cm². The results imply that at low current density, the plating speed is slow and there is sufficient time for the as-plated Ni atoms to rearrange to form a dense coating. At high currents, the plating speed is high, and the limited mass transport of Ni ions leads to a less dense coating.     

Determination of mechanical properties of electroplated Ni thin film using the resonance method

This paper addresses a relatively simple method of measuring the mechanical properties such as Young's modulus and residual stress of electroplated Ni thin film using the resonance method of Atomic Force Microscope. Thin layer of nickel to be measured is electroplated onto the tip side of AFM silicon cantilever and plating thicknesses were measured at the end of each plating step. The measured Young's modulus of nickel at the end of each plating step ranged from 148.04 GPa to 159.90 GPa with the maximum standard deviation of 3.47. The end deflection of electroplated AFM cantilever is also measured as a function of the plated Ni thickness, which is converted into the film stress by appropriate mechanics.     

Development of guide rollers using electroplated carbon fiber-epoxy composite for thin polymer film processing

Since thin polymer films can not sustain the large tension generated from the rotational inertia of a guide roller during start and stop periods of film processing and can be easily damaged by the rough surface of the guide roller, the guide roller should have low rotational inertia, low friction coefficient, high bending stiffness and fine surfaces.

The carbon fiber-epoxy composite material electroplated with chromium has excellent properties for the structure of the guide roller due to its high specific modulus and high damping, which reduces induced vibrations.

In this paper, the design and manufacturing methods as well as the static, dynamic and frictional characteristics of the carbon fiber-epoxy composite rollers electroplated with chromium were investigated using analytical and experimental methods to improve the performance of the high speed guide roller.     

ZnS:Cu polymer nanocomposites for thin film electroluminescent devices

Copper-doped zinc sulphide nanoparticles with varying copper content were synthesized via a coprecepitation method and embedded in polymer thin films by phase transfer technique to examine direct current electroluminescence (DC-EL) properties. A single layer structure (ITO/ZnS:Cu@ polymer/Al) was chosen to examine the influence of film thickness, copper content and polymeric matrix. Two types of devices were investigated based either on an insulating polymethylmethacrylate (PMMA) matrix or a semiconducting poly(9-vinylcarbazole) (PVK) matrix. The resulting DC-EL differs in spectral characteristics showing a broad EL emission over the whole visible range for PMMA based devices and EL with narrow full width at half-maxima values (FWHM) and maxima positions close to those observed in photoluminescence (PL) spectra of particle dispersions.     

Screw dislocation in the two-phase isotropic thin film of an interfacial crack

The screw dislocation in the two-phase isotropic thin film of an interfacial crack has been investigated. The stress field, stress intensity factors at the crack tip and for dislocation emission, crack extension force, strain energy and the image force on the dislocation are obtained and found to be related to the thickness and effective shear modulus. The effect of size on fracture is pronounced when the thickness is smaller than the distance between dislocation and crack tip by a factor of 1000. The effect of the second phase on fracture is pronounced when μ⁽²⁾/μ⁽¹⁾ is in the range from 0.01 to 100. Newton's third law is proved to be valid for any thickness and shear modulus ratio. This result can be reduced to three special cases.     

Textured tapes of three-layer Ni-5% W/Ni-11% Cr composite: Substrates for second-generation superconductors

We have studied the formation of recrystallization texture in three-layer Ni-5% W/Ni-11% Cr composite tapes obtained through cold rolling to 98.4–99.3% followed by high-temperature annealing at 1000–1150°C. It is established that the textured three-layer composite tapes can be used as substrates for creating second-generation high-temperature superconductor (HTS) ribbons. Estimation of the magnetic properties of as-annealed composite tapes showed that their magnetization at HTS working temperatures is lower than that of widely used commercial Ni-5% W alloy tapes.     

Applications of microcrystalline hydrogenated cubic silicon carbide for amorphous silicon thin film solar cells

We demonstrated the fabrication of n-i-p type amorphous silicon (a-Si:H) thin film solar cells using phosphorus doped microcrystalline cubic silicon carbide (μc-3C-SiC:H) films as a window layer. The Hot-wire CVD method and a covering technique of titanium dioxide TiO₂ on TCO was utilized for the cell fabrication. The cell configuration is TCO/TiO₂/n-type μc-3C-SiC:H/intrinsic a-Si:H/p-type μc- SiC_x (a-SiC_x:H including μc-Si:H phase)/Al. Approximately 4.5% efficiency with a V_oc of 0.953 V was obtained for AM-1.5 light irradiation. We also prepared a cell with the undoped a-Si_1−xC_x:H film as a buffer layer to improve the n/i interface. A maximum V_oc of 0.966 V was obtained.     

Investigation of diffusion in the CuAl thin film system

An identification of the phases obtained as a result of diffusion in the CuAl thin film system and an investigation of the phase growth kinetics were carried out by means of electrochemical anode etching. Parabolic growth rates were found for the CuAl and CuAl₂ phases and also for layers with 19–24 at.% Al.     

An inorganic-organic passivation double layer for thin film circuits

If not hermetically encapsulated, thin film hybrid circuits require passivation for various reasons: protection against mechanical attack, long-term humidity diffusion, oxidation of metal films during heat treatment and destruction of oxide layers in electroless plating baths. An inorganic (Al₂O₃, SiO₂ etc.) or organic (photoresist, polyimide) passivation alone cannot meet all requirements simultaneously since most organic coatings do not resist temperatures of more than 150°C whereas evaporated oxide layers are too thin (1 μm or less) for mechanical protection and are often destroyed by non-neutral plating baths.We present a double-layer protective coating for thin film circuits consisting of an evaporated Al₂O₃ thin film and a photoresist layer baked at temperatures near the solder bath temperature. This passivation layer sequence is shown to avoid all the shortcomings of its constituents.     

Fe-18Mn-5Si-8Cr-5Ni-0.1N形状记忆合金组织和性能的研究

研究了Fe-18Mn-5Si8Cr-5Ni-0.1N形状记忆合金的形状记忆效应、回复应力、耐蚀性能.结果表明,在Fe-18Mn-5Si-8Cr-5Ni合金中加入0.1%的氮,对合金的形状记忆效应不利,但当预变形量小于4.5%时,降低幅度较小,在14%～18%左右.在变形量小于4.5%时,含氮合金加热时的回复应力高于未加氮的合金的回复应力;当变形量大于4.5%时,含氮合金的回复应力低于未加氮的合金的回复应力,两种合金的加热时最大回复应力的最大值相近(90 MPa左右).又由于氮具有强烈的固溶强化作用,大大强化了基体,使得合金在冷却过程中因回复应力导致的塑性变形量和二次相变量减小,从而导致合金冷却到室温的回复应力显著提高,当预变形量为6%时,含氮合金的室温回复应力最大,比未加氮的合金的最大室温回复应力高约21%.同时,氮的加入有利于提高合金的耐蚀性能.     

Growth kinetics of the θ phase in AlCu thin film bilayers

The growth kinetics of the θ (Al₂Cu) phase in AlCu thin film bilayers were studied by MeV He⁺ backscattering and X-ray diffraction. In the temperature range 160–200°C the growth is diffusion limited with an activation energy of 1.02 eV and a pre-exponential factor of 7 × 10^?3cm²s^?1. Nucleation of the γ₂ phase occurs at 200°C with long annealing times. There is no evidence of the presence of other phases in the investigated temperature range.     

New chemical methods for the deposition of Cu1·8S and TlSe thin film

New chemical methods for the deposition of thin film of Cu_1·8S and TlSe have been developed. The deposition of Cu_1·8S thin film has been performed by thiourea, ammonia and Cu²⁺ ions at room temperature, while TlSe thin films are obtained from triethanolamine as complexing agent, ammonia, sodium selenosulphate solution and Tl¹⁺ ions at room temperature. The electrical resistance, mobility, carrier concentration and optical band gap have been measured.     

An elasticity problem for an isotropic medium containing thin tunnel inclusions with complex shapes

Summary The state of planar deformation has been examined in an isotropic medium containing a thin tunnel inclusion whose rigidity does not exceed that of the matrix, while the cross section is bounded by a smooth curve of oval type. The treatment involves singular integrodifferential equations for the displacement steps at the inclusion surfaces. Analytic solutions are obtained for these equations and the stresses in the inclusion are determined, as well as the stress concentrations in the matrix around the vertices. The local state of stress around the vertices for an inclusion with a compound configuration can be determined by solving for the corresponding equivalent elliptic tunnel inclusion.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, No. 5, pp. 23–28, September–October, 1989.     

An improved method for the determination of the extinction coefficient of thin film materials

The determination of the extinction coefficient of a material deposited in thin film form is generally made from Wolter's formula using $\text{(R ? R′)}\text{T}$.To avoid the measurement of R′, we have derived an analogous formula involving only R and T in the term $\text{(1 ? R ? T)}\text{T}$. Moreover this new expression can be used in oblique incidence.     

Na-doped Mo target sputtering for Cu(In,Ga)Se2 thin film solar cells

This study employed a Mo–5 % Na thin film on a soda-lime glass substrate as the bottom layers of a Mo back contact using a sputtering process to achieve large area Cu(In,Ga)Se₂ (CIGS) cells application and uniform distribution. Our results demonstrate that increasing the ratio of Mo–5 % Na to Mo film thickness (R %) from 0 to 11 % enhanced the crystallinity of the deposited bi-layer Mo film, thereby increasing surface roughness and slightly reducing resistivity. Following selenization, optimal CIGS crystalline characteristics appeared when R % = 8 % (sodium content = 1.57 at.%), such that secondary phases were not generated, and the surface and depth distribution of sodium were uniform.     

Study on electroplated copper thin film and its interfacial reactions in the EPCu/IMPCu/IMPTaN/SiO2/Si multilayer structure

Electroplated Cu film on a thin seed layer of IMP deposited Cu has been investigated in the EPCu (1 m)/IMPCu (150 nm)/TaN (25 nm)/SiO₂(500 nm)/Si multi-layer structure. The characteristics of Electroplated-Cu films before and after annealing were investigated by means of sheet resistance, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Rutherford Backscattering Spectroscopy (RBS). Annealing at temperatures of higher than 750°C resulted in slightly higher sheet resistance, larger grain sizes and rougher surface. SEM micrograph showed that the agglomeration of EP-Cu film occurred only at annealing temperatures higher than 850°C. During annealing, the EP-Cu grain grew normally and their sizes increased to about five times larger than the thickness of the EP-Cu film but the (111) preferred orientation was maintained up to 950°C. Furthermore, the interfacial reactions between Cu layer and IMP-TaN diffusion barrier were also detected at annealing temperatures of higher than 750°C.