Reader Sensor Structure and its Method of Construction

摘要

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.

主权项

1. A TMR read sensor comprising:
a horizontal lower shield; a horizontal upper shield; a horizontally layered TMR sensor stack formed between said lower shield and said upper shield, wherein said TMR sensor stack has a patterned portion defining a trackwidth; and symmetrically opposed, horizontal junction shields abutting said patterned portion; and wherein said TMR sensor stack comprises:
a pinning layer formed contiguous with said lower shield;a pinned layer formed on said pinning layer;a tunneling barrier layer formed on said pinned layer;a ferromagnetic free layer formed on said tunneling barrier layer; andwherein
said patterned portion is defined by symmetrically opposed lateral sides, wherein said sides laterally bound said ferromagnetic free layer and laterally bound said tunneling barrier layer and wherein a maximum width of said free layer defines a trackwidth; wherein said sides laterally bounding said ferromagnetic free layer and said sides laterally bounding said tunneling barrier layer are coplanar and make an angle θ1 to a vertical direction and wherein said coplanar sides may penetrate, by a minimal penetration amount into an upper surface of said pinned layer; wherein a thickness of said pinned layer is uniformly reduced by said penetration amount and wherein said upper surface of said pinned layer is rendered smooth and planar; wherein said pinned layer and said pinning layer are not laterally patterned and extend laterally and symmetrically, with a constant thickness, beyond said lateral sides; and wherein a layer of isolating oxide conformally covers said upper surface of said pinned layer and said lateral sides of said patterned portion, forming a junction thereat; and wherein said symmetrically disposed pair of junction shields are conformally and contiguously positioned between said upper shield and said layer of isolating oxide and abut said junction.