Electromagnetic and thermomechanic characterization and reliability evaluation

Automatized Measurement of Micromagnets on Wafer-Level in Close Distance

Messung eines Mikromagnet Arrays.
© Fraunhofer ENAS
Measurement of a micromagnet array.

Nowadays miniaturization concerns various technological fields of applications. Recent developments on a novel powder-based MEMS manufacturing process enable to realize micromagnets with a structural size of tenths of a micrometer. As characterization tools for such small magnetic structures are rare, Fraunhofer ENAS started to develop a high-precision measuring device for this purpose in collaboration with their colleagues of the Fraunhofer ISIT. The basis of the development is a three-axis portal robot with a positioning accuracy of 1 µm in every direction, allowing to precisely navigate across the device-under-test (DUT).
Using a 3D hall sensor with minimized package, the achievable vertical distance from the hall element to the DUT is approx. 110 µm. Moreover, a 3D scanning unit creates a heightmap of the DUT that enables a fully automated contour measurement of a whole wafer guaranteeing a constant distance to the surface at every measuring point.
To further enhance the measurement results, appropriate postprocessing by deconvolution is used to filter the disturbing effect of the magnetic field spatial integration related to the hall sensor. The result is a detailed, clear view of the magnetic field strengths of micromagnets.