ResearchPast Projects
Integration ultradünner Magnetfeldsensoren in intelligente Automatisierungskomponenten (UltraMag) - Teilprojekt: Entwicklung ultradünner, dreidimensional messender Magnetfeldsensoren

Integration of Ultrathin Magnetic Field Sensors in Intelligent Automation Components (UltraMag) – Subproject: Development of Ultrathin, Magnetic Field Sensors for Three-Dimensional Measuring

Year:  2011
Funding:  Federal Ministry for Education and Research
Duration:  2009 – 2013
Is Finished:  yes

Motivation 

The aim of this joint project is to improve the performance of electromagnetic drive, control, and measurement systems by implementing ultra-thin magnetic field sensors, which allow magnetic field measurement at previously inaccessible locations due to their low overall height. The measurement data obtained in this way extend the knowledge of the system status and make it possible to optimize operation through refined control algorithms. The spatial and functional implementation requires both the development of suitable, multidimensional measuring magnetic microsensors and the development of a structure and connection technology (AVT) adapted to the requirements of ultra-thin construction for suitable system integration.

Subprojekt Aim (IMPT)

The primary objective of the IMPT subproject is the development of a planar ultra-thin three-dimensional GMR sensor that enables the measurement of small magnetic fields in all three spatial directions. An integrated conductor allows compensation (shielding) of the field to be measured and thus ensures the use of the high sensitivity of the GMR sensor. The development of ultra-thin sensors with concentration and compensation elements and the resulting possibility of measuring in very small gaps should lead to a considerable improvement in performance in electromagnetic drive, control and measuring systems.

Furthermore, investigations are carried out to improve the linearity and sensitivity of GMR for the described application. These investigations include GMR sensor systems based on multilayers and spin valves produced by cathode sputtering. In a further step, we are working on the development of TMR sensors to increase the sensitivity of the sensor system.

A very low overall height of the magnetic field sensors is decisive for the intended use. Therefore, in addition to the development of the sensors, a process for thinning the wafers and a suitable AVT for integration in the intended demonstrators (e.g. in the air gap between the stator and rotor) must also be developed. The aim here is to avoid increasing the overall height by mounting and contacting. The sensor package consists of three parts: the sensor chip, the flexible cable and the ceramic board. The electrical contact of the sensor and the flexible cable is made by ultrasonic wire bonding. To enable successful installation in the demonstrator, the complete package (together with the wires) must not exceed 200 µm in height. A "Thinning-by-Dicing" process developed at the IMPT was used for thinning sensor chips. Through a combination of profiling by means of abrasive cutting, fine lapping and nano grinding and the well-known "dicing by thinning" process, this enables an extreme reduction in thickness and a defect free removal of ultra-thin Si chips.