Magnetron Sputtering of Contact Metallization for TMR Devices

In addition to the magneto-resistive multilayer stack, the metallization and additional coating layers play an important role in the performance and reliability of tunnel magnetoresistance (TMR) sensors. This Application Note shows how to deposit metallization stacks for TMR devices with a scia Magna 200 cluster tool. It covers the process approach, the tool configuration, and the key design considerations.

Why metallization matters for TMR sensors

Magnetron sputtering is a well-established process for fabricating thin-film systems, such as TMR sensors. The high degree of process control enables the deposition of thin, homogeneous and reproducible layers with precisely defined composition and thickness. This is important because the magnetoresistive properties of a TMR sensor depend heavily on the quality and interface structure of the thin-film stack.

The metallization is equally important. It provides reliable electrical contacts and enables efficient signal transmission while maintaining compatibility with the underlying magnetic stack. Additional coatings can serve as protective and insulating layers, or as functional layers for following process steps.

The tool: scia Magna 200 cluster

The scia Magna 200 combines two sputtering modules with a transfer module. One module uses a 300 mm magnetron with rotating magnets for high-rate deposition. The other uses a confocal arrangement of four sputtering targets, each of which can be equipped with a different target material and power supply. This provides high flexibility across applications and process requirements.