Papers by Keyword: Anodic Bonding

Abstract: Silicon wafer bonding opens possibilities in creating MEMS devices and anodic bonding is found to be the most relevant wafer bonding technique process in constructing and packaging MEMS. This paper reports on the bond strength comparison between silicon and different glass based materials via anodic bonding. Two types of glass based surface used pyrex and soda lime glass. Bonding temperature is set at room temperature while a high direct current voltage of 15kV. Experiments were carried out using an in-house designed anodic bonder and the bond strength were measured using a bond strength tester. The anodic approach process was done in two sets which are before and after the cleaning process for each sample. Results show that all samples showed higher bond strength after the cleaning process. Silicon-soda lime glass have higher bonding strength of 1950 Pa compared to silicon-pyrex bonding which only gives 1850 Pa of bond strength.

Abstract: Modeling ideas of physical and chemical processes when using an anodic bonding for materials connection are developed. The kinetics of a charge accumulation in an electrode region in a dielectric is considered. The thickness of a charge layer, electric fields strength and value of the ponderomotive pressure providing connection of materials are calculated. It is shown that the necessary ponderomotive pressure resulting in a dielectric-to-conductor seal is normally about ten MPa and the time required is about ten minutes.

Abstract: Anodic bonding experiments of Pyrex glass and Kovar alloy have been carried out in this investigation. By means of SEM and EDS, microstructures and chemical elements in the joining interfaces were analyzed. With XRD, phase structures in the interfaces were also analyzed. The results show that the joint is made up of three different layers, which are Kovar alloy layer, transition layer and Pyrex glass layer. The transition layer are spinal oxides, which are FeO·SiO₂. By means of MARC software, residual stresses and strains were investigated for the anodic bonding samples of Pyrex glass/Kovar alloy. The maximum residual stress located in the transition layer and the maximum strain located in the Kovar alloy layer. Residual stresses and strains of the sample are significant small and uniform.

Abstract: Based on the triple-stack structure of "sandwich" of three-axis micro-accelerometer, a anodic bonding technology about three-layer of glass-silicon-glass is brought out. As the advantage of the triple-stack structure is introduced, the process of traditional anodic bonding is expounded. Since the bonding in the first time has led the layers of glass and silicon felt together, the strength of the first bonding will be destroyed if the electrode loads on the bonding glass-silicon surface directly in the second time. For this problem, the methed using dielectric material to pass bonding voltage is proposed. The results of the experiment show that the proposed new three-stack bonding method is simple and feasible.

Abstract: A ring-shaped low-frequency resonator operating in the in-plane (2,1) mode was designed and fabricated utilizing anodic bonding of a 9-µm-thick single-crystal silicon to a glass substrate. Although the gap between the ring and the driving electrode was relatively large (900 nm), a high quality factor of 4212 at 1.609 MHz was realized. The motional resistance was 1.853 MW. In addition, the resonant frequency was electrically tuned by varying the dc bias of drive electrodes with 21.5 ppm/V. Therefore, it was expected that this resonator could possibly replace low frequency quarts resonators of a few MHz ranges.

Abstract: With the development of MEMS technology, the pressure sensors, one of mature MEMS devices, are expected to better performance. In order to improve sensors performance, supporting vitreous body shape is elongated and thinned. But the variety of the vitreous body shape brings the new difficulties for anodic bonding between the vitreous body and the silicon during the sensors production, and causes that the common bonding process conditions are unavailable and bonding failure rate dramatically increases. Therefore, this article analyzes the bonding process between slender vitreous body and silicon, and researches on the influence of the vitreous body variety on the pressure, temperature and voltage. The results showed that the bonding is the best when the cantilever elastic deformation is less than 0.5mm, interface temperature loaded from the silicon is 415°C and the voltage 1200V is loaded from the position near H=2mm.

Abstract: A new silicon MEMS process has been proposed utilizing anodic bonding of an extremely thin silicon film (60 m) on a glass substrate, followed by photo lithographically defining micro spring structures on the silicon film and dry etching the silicon film using an inductively coupled plasma (ICP) dry etcher. After that, the underneath glass was selectively etched off using a hydrofluoric (HF) solution to release the micro spring. This technique was successfully applied to a micro vibration detection sensor with the silicon microspring with a cross section of 10 m x 60 m with a length longer than 500 m.

Abstract: 3-layer anodic bonding is one of the key technologies in the manufacture of complicated structure. The microcosmic process and current model of the 3-layer anodic bonding was investigated, and a new technology scheme with better bonding effect was developed. Using the experiment device, quantities of bonding current curves were obtained by the data collecting system. Under tensile testing device, intensity of the bonding was tested. By analysis of the data collected, the 3-layer bonding model was inspected, and the efficacy of the new technology scheme was proved.

Abstract: In this paper, we make a detail analysis of some factors, which affects the electrostatic bonding process. According to the electrical properties of glass, combined with the principle of electrostatic bonding, we analysed the relationship of critical bonding time, voltage and temperature as well as the factors which affect electrostatic bonding. Then we come up with the mathematical model of the intensity and temperature of electrostatic bonding. In accordance with the above-mentioned formula and the experimental data, we can get the following conclusions: the intensity of electrostatic bonding is much greater between 280°C to 370°C; the best temperature for this bonding is about 350°C; however, when the temperature is below 280°C,the intensity of electrostatic bonding is lower due to the great impact of particles under low temperature; but when the temperature is higher than 370°C,the mismatch of coefficient of thermal expansion of silicon and glass gets larger, then as a result, the intensity of this bonding has a significant decrease with the increasing of temperature.

Abstract: To simulate the whole process of anodic bonding accurately, this paper makes the research on the current of anodic bonding with area and point cathode respectively. Based on the known models of anodic bonding, novel current formulas are deduced for anodic bonding with area cathode by means of the relation between glass resistivity and temperature. After calibrated by statistics of experimental data, the formulas quantitatively describe the relation between bonding current with time, as well as bonding voltage and bonding temperature. Further, using spreading model of anodic bonding, an approach to dealing with the problem of point cathode current is presented. The experiments prove that the current formulas from the approach are able to indicate the law of point cathode current.