Roderich Zeiser
University of Freiburg
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Featured researches published by Roderich Zeiser.
electronic components and technology conference | 2012
Roderich Zeiser; Phillip Wagner; Juergen Wilde
Silicon carbide is a promising semiconductor material for sensor applications in harsh environments. To operate SiC-MEMS at high temperature, reliable assembly and packaging technologies are needed. In this paper, packaging technologies for die-attachment and interconnection suitable for SiC-Sensors are presented. They are investigated on their stability, reliability and their thermo-mechanical influence on the sensor element. Active metal brazing, glass soldering and ceramic bonding are used as mounting technologies and Platinum and Palladium wires for electrical interconnection. Different material combinations were examined. Silicon test-chips processed in thin film technology with a metallization suitable for harsh environments were used for conducting and characterization of the technologies. The test-chips were mounted on Al2O3, AlN and Si3N4 substrates to examine the influence of the sensor substrate. The mechanical stress in the chip induced by the packaging process was analyzed by an optical measurement of the chips surface, correlated to an analytical approach and compared to FEM-simulations. The investigation of the mechanical stability of the material compounds was carried out by shear-tests before and after 100 hours storage at 500°C. In this study the glass-solder process with an AlN sensor substrate is the most suited technology in case of the reliability of SiC-MEMS.
2012 4th Electronic System-Integration Technology Conference | 2012
Roderich Zeiser; Philipp Wagner; Juergen Wilde
The objective of this study is to develop and investigate a reliable electrical interconnection for SiC-MEMS, which can sustain high mechanical and thermal loads in harsh environments. Platinum and palladium wire bonds, with a diameter of 25 microns, are used for interconnection of sensors with an operating temperature of 500 °C. Silicon testsensors with TiW/Pt bond pad metallization are processed in thin film technology. The test-chips are mounted with temperature stable assembly techniques on ceramic substrates for reliability evaluation of the package. Ultrasonic bonding process for sensor interconnection is developed in this work and the optimized process parameters are given for both materials. Wire-pull tests with initial devices, after aging and at 300 °C are performed to investigate the stability of the interconnections. An O2-plasma cleaning process of the bond metallization showed significant improvement of the bond reliability. Maximal pull forces up to 20 gf for Pt wires were measured. An increase of the average pull force values compared to untreated specimen for Pt wires of 75 %, for Pd wires of 40 % was observed. The fracture surfaces of devices after the pull-tests were examined by microscope and SEM. Bond-neck break and bond interface fracture were the main bond failure modes. After storage of 200 hours at 500 °C the electrical contact was ensured but a degradation of the bond metallization was observed that leaded to a decrease of obtained pull forces for Pt and Pd. High pull forces of bonds tested at 300 °C were observed with a reduction only by 8 to 10 % for both materials from the initial value.
internaltional ultrasonics symposium | 2013
Jochen Hempel; Dominik Finke; Matthias Steiert; Roderich Zeiser; Michael Berndt; Jürgen Wilde; Leonhard M. Reindl
This paper presents a strain and stress sensitivity investigation of surface acoustic wave (SAW) strain sensors on chip-level. Longitudinal and transversal orientated SAW strain sensors are homogeneously loaded. The sensors response is measured and analyzed with a network analyzer while the sensor substrate stripes are strained precisely. An optical 3D deformation analysis system is used for reference strain measurements. The determined strain on chip-level is compared with strain calculations. High precision strain and stress sensitivities are presented without the cross effects of multilayer measurement setups.
electronic components and technology conference | 2013
Roderich Zeiser; Lukas Lehmann; Volker Fiedler; Juergen Wilde
The flip-chip technology has many advantages over standard wire bonding processes especially as interconnection technique for MEMS operating in harsh environments. In this paper, silver based micro contact bumps are investigated with test assemblies on their reliability for an operating temperature of 500 °C. The contact bump materials are a nano-silver sinter paste and a glass-solder filled with silver particles. Our experiments showed an optimal mixture ratio of silver and glass of 80/20 with regard to stability and electrical performance of the contact material. Silicon based test-chips mounted on Al2O3, AlN and Si3N4 substrates, metallized with platinum were the test devices for process optimization and reliability measurements. The stability and electrical performance of the contact materials were investigated. We used an analytical approach to identify material and process parameters that influence the stress inside a contact bump after processing. Our experimental results indicate a high influence of the sensor substrate CTE and the process temperature on the lifetime in the micro contact. After processing the test-assemblies were exposed to extreme thermal shock cycles with ΔT = 470 K. We analyzed the lifetime of the micro contacts during the cycles with in-situ resistance measurements of the test-structures. Sintered silver and conductive glass contacts are both promising high-temperature flip-chip interconnections. Longer lifetimes of contact bumps with sintered silver were detected. We observed early contact failures after 10 to 20 thermal shocks for the devices with Al2O3 and AlN substrates. A test assembly contacted by silver-sintering on Si3N4 had the first contact failure after 54 thermal shock cycles.
international conference on solid state sensors actuators and microsystems | 2015
Roderich Zeiser; Suleman Ayub; P. Wagner; Jens Müller; S. Henneck; Jürgen Wilde
This work presents a method for a reliable assembly and interconnection of MEMS for very high temperatures. A flip-chip concept for resistive micromechanical pressure sensors with a platinum thin film was developed and sensor-assemblies were fabricated. The investigated metallized ceramic substrates were AlN, Si3N4, a Low-Temperature-Cofired-Ceramic (LTCC) and a zirconia-silicate (ZrSiO4). A borosilicate glass-solder was the die-attachment material and gold stud-bumps were the interconnection. The thermal-mechanical stresses in the sensors, induced by the packaging process due to material-dependent mismatches were analyzed with FEM and optical deformation measurements from 20 to 500 °C. The comparison of the obtained experimental and FE-results revealed a strong influence of the applied substrate on the thermal-mechanical stresses in the chip-membrane which is affecting the output-signal and reliability. Both methods were in good accordance. The two specific silicon-matched ceramic substrates LTCC and ZrSiO4 reduced the stresses in the sensor-element significantly. Furthermore, the electrical characterization of assembled test-sensors revealed a correlation between the package-induced stresses in the chip-membrane and the shift of the sensor-signal after the assembly-process.
Journal of Sensors and Sensor Systems | 2014
Roderich Zeiser; T. Fellner; Jürgen Wilde
Journal of microelectronics and electronic packaging | 2014
Roderich Zeiser; Suleman Ayub; Jochen Hempel; Michael Berndt; Juergen Wilde
electronic components and technology conference | 2017
Nilavazhagan Subbiah; Surajit Ghosh; Juergen Wilde; Roderich Zeiser
international conference on thermal, mechanical and multi-physics simulation and experiments in microelectronics and microsystems | 2014
Roderich Zeiser; Suleman Ayub; Michael Berndt; Jens Müller; Jürgen Wilde
Sensors and Measuring Systems 2014; 17. ITG/GMA Symposium; Proceedings of | 2014
Roderich Zeiser; Suleman Ayub; Juergen Wilde