MAGNETIC TUNNEL JUNCTION WITH LOW DEFECT RATE AFTER HIGH TEMPERATURE ANNEAL FOR MAGNETIC DEVICE APPLICATIONS

摘要

A magnetic tunnel junction is disclosed wherein the reference layer and free layer each comprise one layer having a boron content from 25 to 50 atomic%, and an adjoining second layer with a boron content from 1 to 20 atomic%. One of the first and second layers in each of the free layer and reference layer contacts the tunnel barrier. Each boron containing layer has a thickness of 0.1 to 1 nm and may include one or more B layers and one or more Co, Fe, CoFe, or CoFeB layers. As a result, migration of non-magnetic metals along crystalline boundaries to the tunnel barrier is prevented, and the MTJ has a low defect count of around 10 ppm while maintaining an acceptable TMR ratio following annealing to temperatures of about 400°C. The boron containing layers are selected from CoB, FeB, CoFeB and alloys thereof including CoFeNiB.