Self-aligned perpendicular writer pole and front shield

The present invention relates to a magnetic data storage device, and more particularly to a write pole for a perpendicular writer having improved control over critical dimensions.

As magnetic recording storage densities continue to progress in an effort to increase the storage capacity of magnetic storage devices, magnetic transition (i.e., bit) dimensions and critical features of the recording device are being pushed below 100 nanometers (nm), particularly for writers that operate on the principle of perpendicular recording. This decrease in critical dimensions presents a significant challenge to the manufacture of devices such as perpendicular writers due to the corresponding decrease in the error tolerance margin associated with production of the devices. For example, in a perpendicular writer, the dimensions of the write pole break point (WP BP) and the front shield throat height (FS TH) are critical dimensions defined during the slider lapping process, and typically are targeted to be approximately 100 nm or less. These dimensions have traditionally been defined by two independent photolithography layers in wafer fabrication, which results in an error (3-sigma) of about 50 nm, five times larger than an exemplary 10% tolerance margin. This range of variation results in a poor yield of devices that meet specifications. A design and/or process that reduces the error associated with the production of devices such as these would be a desirable improvement to the state of the art.

The present invention is a write pole structure and a method of forming the write pole structure. The write pole structure has a tip region, and a shield structure is spaced from the write pole by a gap at the tip region. The shield structure includes a front shield and a spacer layer on the back of the front shield. A yoke is formed on the write pole, and an end of the yoke is aligned with the back end of the spacer layer.

The write pole structure is formed by forming a write pole, forming a write gap with non-magnetic material on the write gap at a tip portion of the write pole, forming a front shield structure on the non-magnetic write gap material at the tip portion of the write pole, where the front shield structure includes a front shield and a spacer layer on a back side of the front shield, and forming a yoke on the write pole that has a front edge aligned with a back edge of the spacer layer on the back side of the front shield.

FIGS. 1A-1C are side layer diagrams of a self-aligned perpendicular writer.

FIG. 2 is a top view of a self-aligned perpendicular writer as shown in any of FIGS. 1A-1C .

FIG. 3 is a flow diagram illustrating an example of a procedure for fabricating a self-aligned perpendicular writer.

FIGS. 4 A/ 4 B- 16 A/ 16 B are layer diagrams and end views illustrating exemplary steps of fabricating a self-aligned perpendicular writer.

FIGS. 1A-1C are side layer diagrams of a self-aligned perpendicular writer according to first, second and third embodiments of the present invention. FIG. 1A shows self-aligned perpendicular writer 10 a having self-aligned write pole yoke 12 a on unmilled write pole 14 a . FIG. 1B shows self-aligned perpendicular writer 10 b having self-aligned write pole yoke 12 b on partially milled write pole 14 b . FIG. 1C shows self-aligned perpendicular writer 10 c having self-aligned write pole yoke 12 c on milled-through write pole 14 c . FIG. 2 is a top view of self-aligned perpendicular writer 10 (this view is the same for all three embodiments shown in FIGS. 1A-1C ). In all three embodiments, front shield 16 is spaced from write pole 14 by write gap 18 in the vicinity of air-bearing surface (ABS) 20 . A front shield structure includes front shield 16 having spacer 22 on its back surface facing toward write pole yoke 12 . In accordance with the present invention, the front edge of write pole yoke 12 is precisely aligned with the back edge of spacer 22 , so that the write pole break point (WP BP) and the front shield throat height (FS TH) of perpendicular writer 10 are precisely controllable.

In most existing perpendicular writer designs, the writer yoke is formed first, and the write pole is then formed on top of the writer yoke. As can be seen in FIGS. 1A-1C , self-aligned perpendicular writers 10 a - 10 c are designed with write pole yokes 12 a - 12 c formed on top of write poles 14 a - 14 c . As will be explained in more detail below, this allows certain critical dimensions (such as the write pole break point (WP BP, illustrated in FIG. 2 ) and the front shield throat height (FS TH, illustrated in FIGS. 1A-1C )) to be controlled with greater precision than was possible in prior designs.

FIG. 3 is a flow diagram illustrating an example of a procedure for fabricating a self-aligned perpendicular writer. In an initial step (step 30 ), writer material is deposited or plated on a substrate. Writer features are then patterned (step 32 ) to form the write pole in the proper shape, and material is deposited around the write pole to planarize the write pole so that additional layers can be formed on it (step 34 ). A non-magnetic material is then formed on the planarized write pole to form a write gap (step 36 ), and a front shield is deposited on the non-magnetic write gap material in a tip region of the write pole near the front edge of the writer (step 38 ). A spacer layer is then deposited on the back of the front shield (step 40 ), and the non-magnetic write gap material is etched to open a space for the writer yoke to be formed (step 42 ). Portions of the write pole may also be milled at this point (as shown in the embodiments of FIGS. 1B and 1C ). The self-aligned writer yoke is then deposited utilizing a collimated deposition technique (step 44 ), with the front edge of the writer yoke being aligned with the back of the spacer layer on the back of the front shield. The remainder of the writer is then built over the writer yoke (step 46 ).

FIGS. 4 A/ 4 B- 16 A/ 16 B are layer diagrams and end views illustrating exemplary steps of fabricating a self-aligned perpendicular writer. FIGS. 4A and 4B illustrate the step of depositing or plating write pole 14 on substrate 50 (step 30 , FIG. 3 ).

FIGS. 5A and 5B illustrate the step of patterning writer features to form write pole 14 in the proper shape (step 32 , FIG. 3 ).

FIGS. 6A and 6B illustrate the step of depositing material 52 around write pole 14 to planarize write pole 14 so that additional layers can be formed on it (step 34 , FIG. 3 ).

FIGS. 7A and 7B illustrate the step of forming write gap 54 with non-magnetic material over write pole 14 and planarizing material 52 (step 36 , FIG. 3 ).

FIGS. 8A and 8B illustrate the step of forming front shield 16 on non-magnetic write gap 54 in a tip region near the front edge of write pole 14 (step 38 , FIG. 3 ).

FIGS. 9A and 9B illustrate the step of depositing spacer layer 22 on the back of front shield 16 (step 40 , FIG. 3 ).

FIGS. 10A and 10B , 11 A and 11 B, and 12 A and 12 B illustrate the step of etching the material of non-magnetic write gap 54 behind the front shield structure (including spacer layer 22 and front shield 16 ) in order to open a space for the writer yoke to be formed (step 42 , FIG. 3 ). FIGS. 10A and 10B illustrate this step with no milling of write pole 14 a , FIGS. 1A and 1B illustrate this step with partial milling of write pole 14 b , and FIGS. 12A and 12B illustrate this step with write pole 14 c having a back portion milled through.

FIGS. 13A and 13B , 14 A and 14 B, and 15 A and 15 B illustrate the step of depositing self-aligned writer yokes 12 a (FIGS. 13 A and 13 B—unmilled write pole 14 a ), 12 b (FIGS. 14 A and 14 B—partially milled write pole 14 b ) and 12 c (FIGS. 15 A and 15 B—milled-through write pole 14 c ) (step 44 , FIG. 3 ). In all three embodiments, self-aligned writer yoke 12 is deposited utilizing a collimated deposition technique (such as collimated sputtering or plasma deposition, or other known collimated deposition techniques), so that the front edge of writer yoke 12 is aligned with the back of spacer layer 22 on the back of front shield 16 . In an exemplary embodiment, writer yoke 12 is formed with a bevel angle between about 20 and 45 degrees, such as about 30 degrees in one particular embodiment. The writer yoke 12 provides an extended magnetic flux delivery path to write pole 14 which increases the writer efficiency, and the beveled front edge of writer yoke 12 functions as the writer pole break point (WP BP) parameter that is critical to dimensionally control.

FIGS. 16A and 16B illustrate the step of building the remainder of the writer over write yoke 12 a (step 46 , FIG. 3 ). This step is only shown with respect to the embodiment in which the write pole is unmilled for the sake of simplicity, since the step would be similar for the partially milled write pole and the milled-through write pole embodiments as well. Specifically, coils 56 , magnetic stud 58 , return pole 60 , shield element 62 and insulating layer 64 are formed to build the writer, as is generally known in the art.

The write pole structure of the present invention allows both the front shield throat height (FS TH) and the writer pole break point (WP BP) to be defined by a single lapping step. The front shield throat height (FS TH) is determined by the amount of lapping from the front side of the writer to form a front writer surface (such as an air bearing surface in a conventional disc drive application, for example). The amount of lapping is precisely controllable by advanced lapping techniques known in the art, such as by using a writer electrical lapping guide (WELG), for example. In addition, the writer pole break point (WP BP) is defined by the position of the front edge of writer yoke 12 , which is controlled by the process described above to have a front edge that is precisely aligned with the back edge of spacer 22 on the back of front shield 16 . Controlling these two dimensions with a single, high precision lapping step, rather than in two independent photolithographic steps as was done in convention designs, provides a significant reduction in the tolerance error of the dimensions, producing greater yields of products that can meet stringent specifications.

The write pole structure disclosed above employs a writer yoke on top of the write pole, rather than below the write pole as in conventional designs, and is formed by a process that aligns a front edge of the writer yoke with a back edge of a front shield structure. As a result, both the front shield throat height (FS TH) and the writer pole break point (WP BP) of the writer are precisely controllable with a single lapping step, reducing error associated with fabrication of the writer. Finite element modeling (FEM) has shown that the write pole structure disclosed above is able to produce at least the same fields and gradients that are achieved by traditional perpendicular writer designs with front shields. The design of the present invention is therefore able to provide greater yields of devices that meet specifications than prior designs.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.