Patent Application
20070020386
Embodiments of the present invention relate to the fields of manufacturing semiconductors and hard disk drives, and more particularly to systems and methods for encapsulation of chemically amplified resist template for low pH electroplating.
Hard disk drives are used in almost all computer system operations. In fact, most computing systems are not operational without some type of hard disk drive to store the most basic computing information such as the boot operation, the operating system, the applications, and the like. In general, the hard disk drive is a device which may or may not be removable, but without which the computing system will generally not operate.
The basic hard disk drive model was established approximately 50 years ago and resembles a phonograph. That is, the hard drive model includes a plurality of storage disks or hard disks vertically aligned about a central core that spin at a standard rotational speed. A plurality of magnetic read/write transducer heads, for example, one head per surface of a disk, is mounted on the actuator arm. The actuator arm is utilized to reach out over the disk to or from a location on the disk where information is stored. The complete assembly, e.g., the arm and head, is known as a head gimbal assembly (HGA).
In operation, the plurality of hard disks is rotated at a set speed via a spindle motor assembly having a central drive hub. Additionally, there are channels or tracks evenly spaced at known intervals across the disks. When a request for a read of a specific portion or track is received, the hard disk drive aligns a head, via the arm, over the specific track location and the head reads the information from the disk. In the same manner, when a request for a write of a specific portion or track is received, the hard disk drive aligns a head, via the arm, over the specific track location and the head writes the information to the disk.
Over the years, refinements of the disk and the head have provided great reductions in the size of the hard disk drive. For example, the original hard disk drive had a disk diameter of 24 inches. Modern hard disk drives are generally much smaller and include disk diameters of less than 2.5 inches (micro drives are significantly smaller than that).
The recording or read/write heads of modern hard disk drives do not actually make contact with the recording media. Rather the heads “fly” on a cushion of air generated by the relative motion of the head over a rapidly spinning platter or disk comprising the recording media. The ability of a head to fly at a desirable height is a critical performance aspect of hard disk drives. Such flying heads are generally referred to or known as “sliders.” As recording density increases, the slider flying height, e.g., the distance between a slider and a recording media surface, generally decreases. Such decreases in flying height typically require ever-flatter slider surfaces. A lapping process typically determines a flatness characteristic of a slider.
A wafer is a basic “building block” upon which numerous processing actions take place to produce multiple components. Wafers form such a building block for the production of magnetic read and/or write heads (“sliders”) as used in hard disk drives. The production of such devices can comprise many different processing steps. It is not uncommon for hundreds of operations to be performed on wafers to produce magnetic heads. In recording head technology, the volume or size of the recording sensor is very small. For example, modern recording, or write heads are of the order of 100 nm. Typically, such sensors become ever smaller with successive generations of hard drive technology.
The on-going increase in areal recording density and corresponding size reduction for read and write heads is driving head manufacturing processes toward higher resolution deep ultra violet photolithography. For example, deep ultra violet light, e.g., light with a wavelength of about 248 nm, can image smaller structures with greater precision than light with a longer wavelength, e.g., approximately 360 nm. In addition, the same trends towards ever smaller head sizes and feature dimensions is also driving a trend towards the use of “stronger” magnetic materials in the construction of such heads. For example, smaller heads will generally advantageously utilize materials characterized by a greater magnetic moment than is characteristic of larger heads.
The use of deep ultra violet photolithography generally correspondingly requires the use of chemically amplified resist materials, while the use of higher magnetic moment materials generally necessitates plating in very low pH (highly acidic) baths. Unfortunately, chemically amplified resist materials are generally not well suited to very low pH plating baths. For example, chemically amplified resist materials, especially low activation and hybrid types, are generally inherently unstable in an acidic environment. Stresses in thick chemically amplified resist materials induced by low pH plating baths can cause fractures and shrinkage in the resist layers, resulting in “worms.” Such worms or cracks can undermine adhesion of the resist layers, resulting in deleterious under plating of head structures.
Accordingly, there is a need for systems and methods for encapsulation of chemically amplified resist template for low pH electroplating. Additionally, in conjunction with the aforementioned need, systems and methods for encapsulation of chemically amplified resist template for low pH electroplating that enable decreased head feature dimensions are desired. A further need, in conjunction with the aforementioned, is for encapsulation of chemically amplified resist template for low pH electroplating in a manner that is compatible and complimentary with existing wafer processing systems and manufacturing processes.
Accordingly, systems and methods for encapsulation of chemically amplified resist template for low pH electroplating are disclosed. In a first method embodiment, a resist template structure is formed on a wafer. Substantially all surfaces of the resist template structure are encapsulated to form an encapsulated structure. Magnetic materials are plated onto the encapsulated structure.
In accordance with another embodiment of the preset invention, a magnetic head comprises a metal plating layer and a chemically amplified resist structure. An encapsulating layer is disposed between the chemically amplified resist structure and the chemically amplified resist structure for protecting the chemically amplified resist structure from the metal plating layer.
Reference will now be made in detail to the alternative embodiment(s) of the present invention, systems and methods for encapsulation of chemically amplified resist template for low pH electroplating. While the invention will be described in conjunction with the alternative embodiment(s), it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.
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, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.
In the embodiment shown, each arm 125 has extending from it at least one cantilevered load beam and suspension 127. A magnetic read/write transducer or head is mounted on a slider 129 and secured to a flexure that is flexibly mounted to each suspension 127. The read/write heads magnetically read data from and/or magnetically write data to disk 115. The level of integration called the head gimbal assembly is head and the slider 129, which are mounted on suspension 127. The slider 129 is usually bonded to the end of suspension 127. The head is typically pico size (approximately 1250×1000×300 microns) and formed from ceramic or intermetallic materials. The head also may be of “femto” size (approximately 850×700×230 microns) and is pre-loaded against the surface of disk 115 (in the range two to ten grams) by suspension 127.
Suspensions 127 have a spring-like quality, which biases or urges the air-bearing surface of the slider 129 against the disk 115 to cause the slider 129 to fly at a precise distance from the disk. A voice coil 133 free to move within a conventional voice coil motor magnet assembly 134 (top pole not shown) is also mounted to arms 125 opposite the head gimbal assemblies. Movement of the actuator 121 (indicated by arrow 135) by controller 119 moves the head gimbal assemblies along radial arcs across tracks on the disk 115 until the heads settle on their respective target tracks. The head gimbal assemblies operate in a conventional manner and move in unison with one another, unless drive 111 uses multiple independent actuators (not shown) wherein the arms can move independently of one another.
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It is to be appreciated that the conventional use of a polymer bonding material, e.g., the RELACS® process, is to shrink a feature, e.g., a hole diameter or trench width, to a size less than the critical dimension (CD) of the process. A cross-linked polymer layer on the interior of such a hole effectively shrinks the diameter of such a hole (width of a trench). In a conventional use of a polymer bonding material, a deep ultra-violet “flood exposure” of the patterned photoresist film is not performed. Thus only the vertical surfaces of the pattern have sufficient acid concentration to form a cross-linked polymer layer. Consequently, horizontal surfaces do not react with polymer bonding materials to form a cross-linked polymer. As such, conventional usage of polymer bonding materials does not produce cross-linked polymer layers across an entire resist structure.
In contrast to the conventional art, embodiments in accordance with the present invention expose an entire resist structure, e.g., chemically amplified resist template structure 200, to deep ultra violet light energy. Consequently, substantially all surfaces of a resist structure are coated with polymer bonding materials, and cross-linked polymer layers are formed on substantially all such surfaces. Such cross-linked polymer layers are utilized to provide an encapsulating layer of protection for subsequent low pH electroplating.
In 320, substantially all surfaces of the resist template structure are encapsulated to form an encapsulated structure. The encapsulated structure can comprise a cross-linked polymer. Cross-linked polymer layer 220 of
In 330, magnetic materials are plated onto the encapsulated structure, forming a pre-head structure. See, for example, electroplated structure 230 of
In optional 340, the pre-head structure is processed to form a magnetic head. Such processing of a pre-head structure into a magnetic head is well suited to a variety of well known methods.
Thus, embodiments of the present invention provide an apparatus and method of encapsulation of chemically amplified resist template for low pH electroplating. Additionally, in conjunction with the aforementioned benefit, embodiments of the present invention provide systems and methods for encapsulation of chemically amplified resist template for low pH electroplating that enable decreased head feature. A further benefit, in conjunction with the aforementioned benefits, encapsulation of chemically amplified resist template for low pH electroplating is provided in a manner that is compatible and complimentary with existing wafer processing systems and manufacturing processes.
While the method of the embodiment illustrated in flow chart 300 shows specific sequences and quantity of operations, the present invention is suitable to alternative embodiments. For example, not all the operations provided for in the methods are required for the present invention. Furthermore, additional operations can be added to the operations presented in the present embodiment. Likewise, the sequences of operations can be modified depending upon the application.
Embodiments in accordance with the present invention, encapsulation of chemically amplified resist template for low pH electroplating, are thus described. While the present invention has been described in particular embodiments, it should be appreciated that the present invention should not be construed as limited by such embodiments, but rather construed according to the below claims.
