Symmetrical shaper for an ion beam deposition and etching apparatus

A shaper for shaping an ion beam and that can be used for both deposition and etching is described. The shaper includes a plate that is placed between an ion beam grid and an ion beam source. The plate covers holes in the grid, and is shaped and dimensioned such that the plate does not partially cover any holes in the grid that are directly adjacent to the plate. A hole is configured to mount the shaper at a center of the grid and at least one other hole is configured to secure the shaper to the grid to prevent the shaper from rotating relative to the grid. A center mount portion covers holes in the grid. The plate has two axes of reflection symmetry. The uniformity of both deposition and etching is improved.

TECHNICAL FIELD

This invention relates generally to the field of deposition and etching processes and devices that use ion beams.

BACKGROUND

Direct access storage devices (DASDs) have become part of everyday life, and as such, the capability to manipulate and store larger amounts of data at greater speeds is expected. To meet these expectations, DASDs such as hard disk drives (HDDs) have undergone many changes.

The basic hard disk drive model resembles a phonograph. That is, the hard disk drive model includes a storage disk, or hard disk, that spins at a standard rotational speed. An actuator arm with a suspended slider is utilized to reach out over the disk. The arm carries a head assembly that has a magnetic read/write transducer, or head, for writing or reading information to or from a location on the disk. An air bearing surface (ABS) on the slider allows the slider to be flown very close to the surface of a disk. The complete head assembly, e.g., the suspension and head, is called a head gimbal assembly (HGA).

Data is recorded onto the surface of a disk in a pattern of concentric rings known as data tracks. One way to increase the amount of data that can be stored on a disk is to make each data track narrower so that the tracks can be placed closer together. But, as tracks are narrowed, the signal-to-noise ratio is worsened, making it more difficult to discern signals from the head. Signal-to-noise ratio can be improved by positioning the head closer to the disk surface. Thus, the height of the slider above the disk (referred to as fly height) can be an important parameter. Another important parameter is the distance between the bottom surface of the head and the bottom surface of the substrate to which the head is attached (referred to as pole tip recession). In general, as the spacing between the head and the disk surface is narrowed, it becomes more important to tightly control the flatness and uniformity of surfaces such as the ABS, in order to reduce the probability of contact between the head and a disk.

Ion milling is a popular technique for forming the ABS on a slider. However, with distances and tolerances measured in terms of nanometers, even minute deviations in the topography of a surface can be very significant. In order to achieve the desired surface uniformity, conventional ion milling techniques need to be improved beyond their current capabilities.

SUMMARY

A shaper for shaping an ion beam is described. The shaper can be used for both deposition and etching. The shaper includes a plate that is placed between an ion beam grid and an ion beam source. The plate covers holes in the grid, and is shaped and dimensioned such that the plate does not partially cover any holes in the grid that are directly adjacent to the plate. A hole is configured to mount the shaper at a center of the grid and at least one other hole is configured to secure the shaper to the grid to prevent the shaper from rotating relative to the grid. A center mount portion covers holes in the grid. The plate has two axes of reflection symmetry. The uniformity of both deposition and etching is improved.

DETAILED DESCRIPTION

Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present invention.

FIG. 1illustrates an example of an ion beam deposition and etching apparatus10that utilizes an ion beam shaper30in accordance with embodiments of the present invention.FIG. 1is not to scale. In the example ofFIG. 1, the apparatus10includes a grid15that is mounted on an ion beam gun, or source,19.FIG. 1includes a side view showing grid15installed in apparatus10, and a top view showing an enlarged version of grid15(as if grid15had been removed from apparatus10and rotated for ease of viewing).

A specimen11is mounted on a table17such that the center23of the grid15, the table17and the specimen11are aligned. Although not shown inFIG. 1, the specimen11and the grid15may be mounted at an angle relative to one another. That is, the specimen11and grid15are not necessarily parallel to each other, and therefore the ion beam's angle of incidence may not be perpendicular to the specimen11.

The table17and/or the grid15can be rotated—in general, the specimen11and the grid15can be rotated relative to one another.

Grid15includes a large number of holes, exemplified by hole21. Grid15may also include regions (other than the regions between adjacent holes) that are free of holes. Although not shown inFIG. 1, the holes21extend to the periphery of grid15.

As specimen11is rotated relative to the grid15, ion beam source19emits an ion beam25onto the surface of grid15. The beam25is filtered by grid15, and relatively small ion “beamlets”27are emitted from the grid15. Using techniques known in the art and so not described in detail herein, the beamlets27can be used to deposit material onto specimen11or to etch material from specimen11.

It is desirable that ion beam density be uniform across the surface of the specimen11, so that material is deposited uniformly across the specimen's surface or so that etching is uniform across the specimen's surface. To achieve such uniformity, a shaper30is mounted onto either the upper or lower surface of grid15. In one embodiment, the ion beam source19includes a plasma chamber and a set of beam grids. In such an embodiment, the shaper30is mounted on the innermost grid (the grid closest to the plasma chamber).

Again,FIG. 1is not to scale. In actuality, the surface area of shaper30is relatively small compared to the surface of grid15. For example, shaper30may cover less than about five (5) percent of the grid15.

According to embodiments of the present invention, the shaper30is dimensioned and shaped such that it does not partially cover any of the holes21. That is, in one embodiment, each of the holes21in grid15is either completely closed by shaper30or is completely exposed to an incident ion beam.

In operation, as the specimen11is rotated beneath the source19and grid15, ion beamlets27that are not blocked by shaper30are able to reach specimen11. Empirical results demonstrate that, with the use of shaper30, deposition and etching are uniform across the entire radius of specimen11(seeFIG. 4). Significantly, shaper30can be used for both deposition and etching and achieves uniform results for both.

FIGS. 2 and 3illustrate ion beam shaper30according to one embodiment of the present invention. Shaper30is essentially a relatively thin and flat plate formed from a durable material such as molybdenum. In one embodiment, shaper30and grid15are made of the same material.

With reference toFIG. 2, shaper30has reflective (bilateral, mirror) symmetry about a first axis41and also has reflective symmetry about a second axis42that is perpendicular to the first axis. In the present embodiment, shaper30includes a hole34that is used to mount the shaper at the center of the grid15ofFIG. 1(the hole34is aligned with the center of the grid15and a screw or other type of fastening mechanism is inserted through hole34into grid15). In a similar manner, other holes, such as hole35, can be used to secure shaper30to grid15and to prevent the shaper from rotating relative to the grid.

A first arm37, measured from the center mount portion36, extends radially in one direction (R1) while a second arm38, also measured from the center mount portion36, extends radially in the opposite direction (R2). In one embodiment, each of the arms37and38covers53holes in grid15(FIG. 1). Additional holes are covered by the center mount portion36.

As shown inFIG. 3, each of the arms37and38of shaper30includes a first portion51that is substantially rectilinear in shape. Each arm37and38also includes a second portion52that is wider (W) and longer (L) than first portion51. The second portion52includes a first region61that is substantially rectilinear in shape, and a second region62that tapers, forming essentially a triangular shape. Each arm37and38also includes a third portion53that is wider than the second portion52, and is essentially chevron-shaped (V-shaped). Each arm37and38also includes a fourth portion54that is wider than the third portion53, and that is also essentially chevron-shaped. In general, the width of shaper30increases in the radial or lengthwise direction. In one embodiment, shaper30has an overall length of about 5 inches and a maximum width of about two (2) inches.

With reference again toFIG. 1, before passing through grid15, some portions of the ion beam25will have a greater density of ions than other portions of the beam. The shaper30blocks the higher density portions of the beam25, such that the ion beamlets27that reach the specimen11are more uniform and thus will produce a more uniform deposition or etch pattern on the surface of the specimen. Because shaper30blocks the higher density portions of the ion beam, the overall intensity of the ion beam is reduced, which may result in reduced deposit and etch rates. However, the reduction in these rates is balanced by the advantages that come with improved uniformity. For example, when applied to the fabrication of hard disk drives (HDDs)—specifically, to the fabrication of the air bearing surface (ABS) of a slider—the improved uniformity results in improved ABS topography after deposition and etch, thus allowing the read/write head to be situated closer to the surface of a storage disk without increasing the probability of contact between the head and the disk surface.

FIG. 4is a graph70illustrating ion beam density versus radius (e.g., a radius along the surface of a specimen). Curve1shows that, using shaper30ofFIGS. 1-3, the beam density is relatively flat across the surface of a specimen. Significantly, even at the periphery of a specimen, the beam density remains relatively flat, for both deposition and etch. In contrast, as represented by curve2, beam density is significantly diminished at the periphery of a specimen when a conventional etch or deposition technique is used.

Because the beam density remains relatively flat across the surface of a specimen, the amount of material deposited or removed during deposition and etching will be uniform across the surface of the specimen. Indeed, empirical data demonstrates that uniform deposition and etching across the surface of a specimen is realized using shaper30, over a wide range of operating parameters including beam density, mounting angle (the angle between the specimen and the beam), and beam power, voltage or current. Notably, with shaper30, both uniform deposition and uniform etching are achieved over the range of operating parameters. Thus, the shaper30does not have to be removed and replaced with a different shaper between deposition and etching.

In summary, embodiments in accordance with the present invention pertain to an ion beam shaper that can be used during both deposition and etch, and that can improve both deposition and etch uniformity across the entire surface of a specimen. Thus, elements such as the air bearing surface of a slider in an HDD can be made to finer tolerances, which in turn allows a read/write head to be located closer to the surface of a disk, reducing signal-to-noise ratio and allowing more information to be stored on the disk.