Kinetics Of Intermetallic Compound Formation Research Articles

Kinetic study of a solid-state reaction in Ag/Al multilayer thin films by in situ electron diffraction and simultaneous thermal analysis

A solid-state reaction process in Ag/Al multilayer thin films has been investigated by the methods of in situ electron diffraction, simultaneous thermal analysis, transmission electron microscopy and X-ray diffraction with the aim of studying the phase formation kinetics of intermetallic compounds. The sequence of the phase transformations in the solid-state reaction has been established: Ag+Al→(Ag)+(Al)→(Ag)+δ-Ag2Al→μ-Ag3Al. The process of the solid-state interaction has been shown to consist of two steps; each of them is described by a kinetic model of the nth order reactions with autocatalysis. The kinetic parameters of the autocatalytic process of the phase formation for δ-Ag2Al and µ-Ag3Al, have been determined, in particular, their apparent activation energy: 126 kJ/mol and 106 kJ/mol, respectively.

Kinetics of intermetallic compound formation in thermally evaporated Ag-In bilayers

The kinetics of intermetallic compound (IMC) formation in thermally evaporated Ag-In bilayers, with In on top of Ag, was investigated using X-ray diffractometry, applied to the surfaces of the bilayer specimens, as well as scanning electron microscopy, applied to cross-sections of the bilayer specimens, prepared by a focused ion beam instrument. IMC formation was followed at room temperature as well as at elevated temperatures of 50 °C, 60 °C, and 70 °C. Two distinct growth regimes were observed coinciding with the availability of pure In. The AgIn2 IMC nucleated initially, followed by nucleation of the Ag2In IMC. The growth of AgIn2 was found to be controlled by both diffusional processes as well as interfacial reactions. The growth of the Ag2In IMC is dominantly diffusion-controlled. An interdiffusion coefficient of D=1.1±3.9·10−4 cm2 s−1 exp(−60.5±9.2 kJ mol−1R−1T−1) was obtained for the Ag2In IMC. The observations were discussed in terms of the interplay of thermodynamic and kinetic constraints.

Study of the Au/In Reaction for Transient Liquid-Phase Bonding and 3D Chip Stacking

The latest three-dimensional (3D) chip-stacking technology requires the repeated stacking of additional layers without remelting the joints that have been formed at lower levels of the stack. This can be achieved by transient liquid-phase (TLP) bonding whereby intermetallic joints can be formed at a lower temperature and withstand subsequent higher-temperature processes. In order to develop a robust low-temperature Au/In TLP bonding process during which all solder is transformed into intermetallic compounds, we studied the Au/In reaction at different temperatures. It was shown that the formation kinetics of intermetallic compounds is diffusion controlled, and that the activation energy of Au/In reaction is temperature dependent, being 0.46 eV and 0.23 eV for temperatures above and below 150°C, respectively. Moreover, a thin Ti layer between Au and In was found to be an effective diffusion barrier at low temperature, while it did not inhibit joint formation at elevated temperatures during flip-chip bonding. This allowed us to control the intermetallic formation during the distinct stages of the TLP bonding process. In addition, a minimal indium thickness of 0.5 μm is required in order to enable TLP bonding. Finally, Au/In TLP joints of ∅40 μm to 60 μm were successfully fabricated at 180°C with very small solder volume (1 μm thickness).

Polarity effect of electromigration on kinetics of intermetallic compound formation in Pb-free solder V-groove samples

Intermetallic compound (IMC) formation is critical for the reliability of microelectronic interconnections, especially for flip chip solder joints. In this article, we investigate the polarity effect of electromigration on kinetics of IMC formation at the anode and the cathode in solder V-groove samples. We use V-groove solder line samples, with width of 100 μm and length of 500–700 μm, to study interfacial IMC growth between Cu electrodes and Sn-3.8Ag-0.7Cu (in wt %) solder under different current density and temperature settings. The current densities are in the range of 103 to 104A∕cm2 and the temperature settings are 120, 150, and 180 °C. While the same types of IMCs, Cu6Sn5 and Cu3Sn, form at the solder∕Cu interfaces independent of the passage of electric current, the growth of the IMC layer has been enhanced by electric current at the anode and inhibited at the cathode, in comparison with the no-current case. We present a kinetic model, based on the Cu mass transport in the sample, to explain the growth rate of IMC at the anode and cathode. The growth of IMC at the anode follows a parabolic growth rule, and we propose that the back stress induced in the IMC plays a significant role. The model is in good agreement with our experimental data. We then discuss the influence of both chemical force and electrical force, and their combined effect on the IMC growth with electric current.

Kinetics of intermetallic compound formation at 91Sn–8.55Zn–0.45Al lead-free solder alloy/Cu interface

The kinetics of intermetallic compounds (IMCs) formation at the 91Sn–8.55Zn–0.45Al lead-free solder alloy/Cu substrate interface during soldering and subsequent aging have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM) and electron diffraction (ED). From the XRD results, γ-Cu 5Zn 8 and Cu 6Sn 5 are found in the eutectic 91Sn–8.55Zn–0.45Al solder alloy/copper interface, but no γ′-Cu 9Al 4 is formed in the wetted samples aged at 423 K for 250 h. However, by TEM observation and ED analysis, γ′-Cu 9Al 4 is found at the interface of the solder alloy and the Cu substrate, and the IMC growth can be expressed as X = (Dt) 1/2. The activation energy of the γ-Cu 5Zn 8 layer growth in 91Sn–8.55Zn–0.45Al solder alloy/Cu interface is determined as 53.77 kJ/mol.

Réaction à l'état solide dans les couches minces du système binaire Cu/Sb

The formation kinetics of intermetallic compounds in Cu/Sb thin films in the temperature range 473–623 K is studied by X-ray and electron diffraction. It is established that the Cu 2Sb phase begins to form during the deposition of the second layer. In the range 473–573 K, independently of film composition, only the Cu 2Sb phase forms and grows, even though the equilibrium diagram predicts two (Cu 2Sb and Cu 9Sb 2). A supplementary annealing of these samples at 623 K in the case where we have a copper excess ( N Cu > N Sb) leads to the complete transformation of Cu 2Sb to the Cu 9Sb 2 phase. However, in the case of an antimony excess ( N Cu < N Sb) we do not observe any transformation. During an annealing at 623 K of as-evaporated samples, in a first reaction stage both the Cu 2Sb and the Cu 9Sb 2 phases appear simultaneously whatever the film composition. Then the Cu 2Sb changes completely to the Cu 9Sb 2 phase if N Cu > N Sb, whereas both phases always coexist if N Sb > N Cu.

Fe-Zn混合粉末圧粉体における金属間化合物相の形成過程について

Fe-Zn混合粉末圧粉体における金属間化合物相の形成過程について

Chronopotentiometric studies on the formation kinetics of intermetallic compounds in mercury.

Chronopotentiometric studies on the formation kinetics of intermetallic compounds in mercury.