Headway Technologies, Incorporated

Minghui Yu

Min Li

Cherng Chyi Han

Hui-Chuan Wang

Jianing Zhou

Ruhang Ding

Tong Zhao

Min Zheng

A TMR (tunneling magnetoresistive) read sensor is formed in which a portion of the sensor stack containing the ferromagnetic free layer and the tunneling barrier layer is patterned to define a narrow trackwidth, but a synthetic antiferromagnetic pinning/pinned layer is left substantially unpatterned and extends in substantially as-deposited form beyond the lateral edges bounding the patterned portion. The narrow trackwidth of the patterned portion permits high resolution for densely recorded data. The larger pinning/pinned layer significantly improves magnetic stability and reduces thermal noise, while the method of formation eliminates possible ion beam etch (IBE) or reactive ion etch (RIE) damage to the edges of the pinning/pinned layer.

Reader sensor structure and its method of construction

A two part ion beam etch sequence involving low energy (&#x3c;300 eV) is disclosed for fabricating a free layer width (FLW) as small as 20-25 nm in a MTJ element. A first etch process has one or more low incident angles and accounts for removal of 70% to 100% of the MTJ stack that is not covered by an overlying photoresist layer. The second etch process employs one or more high incident angles and a sweeping motion that is repeated during a plurality of cycles. Sidewall slope may be adjusted by varying the incident angle during either of the etch processes. FLW is about 30 nm less than an initial critical dimension in the photoresist layer while maintaining a MR ratio over 60% and low RA (resistance&#xd7;area) value of 1.0 ohm-&#x3bc;m.

Two step method to fabricate small dimension devices for magnetic recording applications

A three step ion beam etch (IBE) sequence involving low energy (&#x3c;300 eV) is disclosed for trimming a sensor critical dimension (free layer width=FLW) to less than 50 nm. A first IBE step has a steep incident angle with respect to the sensor sidewall and accounts for 60% to 90% of the FLW reduction. The second IBE step has a shallow incident angle and a sweeping motion to remove residue from the first IBE step and further trim the sidewall. The third IBE step has a steep incident angle to remove damaged sidewall portions from the second step and accounts for 10% to 40% of the FLW reduction. As a result, FLW approaching 30 nm is realized while maintaining high MR ratio of over 60% and low RA of 1.2 ohm-&#x3bc;m. Sidewall angle is manipulated by changing one or more ion beam incident angles.

Method to fabricate small dimension devices for magnetic recording applications

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Fremont, CA, United States of America

Minghui Yu