Patent Application
20150037613
The heat assisted magnetic recording (HAMR) process can involve an environment that can be extremely corrosive because of the high temperature and exposure to corrosive chemistries. Furthermore, designs using close head-media spacing will experience more rapid wear of any narrow, protruded features such as write poles. Because of the harsh environment and the desire to protect some of the more delicate structures, for example the near field transducer (NFT) and the write pole for example; there remains a need for different types of overcoats.
A magnetic device including a magnetic writer; and an overcoat positioned over at least the magnetic writer, the overcoat including tantalum oxide (TayOx), where y ranges from about 1 to 2 and x ranges from about 2 to 5, or mixtures thereof.
A method of forming an article, the method including forming a magnetic structure on a substrate, the magnetic structure having a first surface adjacent the substrate and a second opposing surface; and forming a tantalum oxide layer on the second surface of at least the magnetic structure.
A method of forming an article, the method including forming a magnetic structure on a substrate; forming a tantalum layer on at least the magnetic structure; and oxidizing at least a portion of the tantalum layer to form a tantalum oxide layer.
The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.
The figures are not necessarily to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.
In the following description, reference is made to the accompanying set of drawings that form a part hereof and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.
Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.
The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
“Include,” “including,” or like terms means encompassing but not limited to, that is, including and not exclusive. It should be noted that “top” and “bottom” (or other terms like “upper” and “lower”) are utilized strictly for relative descriptions and do not imply any overall orientation of the article in which the described element is located.
Disclosed overcoats can advantageously provide devices that may be more robust in high temperature environments, such as HAMR. Disclosed methods of making such overcoats are also provided herein.
Disclosed herein are NFTs and devices that include such NFTs.
For heat assisted magnetic recording (HAMR), electromagnetic radiation, for example, visible, infrared or ultraviolet light is directed onto a surface of the data storage media to raise the temperature of a localized area of the media to facilitate switching of the magnetization of the area. Recent designs of HAMR recording heads include a thin film waveguide on a slider to guide light toward the storage media and a near field transducer to focus the light to a spot size smaller than the diffraction limit. While
An insulating material 62 separates the coil turns. In one example, the substrate can be AlTiC, the core layer can be Ta2O5, and the cladding layers (and other insulating layers) can be Al2O3. A top layer of insulating material 63 can be formed on the top pole. A heat sink 64 is positioned adjacent to the sloped pole piece 58. The heat sink can be comprised of a non-magnetic material, such as for example Au.
As illustrated in
The storage media 16 is positioned adjacent to or under the recording head 30. The waveguide 42 conducts light from a source 78 of electromagnetic radiation, which may be, for example, ultraviolet, infrared, or visible light. The source may be, for example, a laser diode, or other suitable laser light source for directing a light beam 80 toward the waveguide 42. Specific exemplary types of light sources 78 can include, for example laser diodes, light emitting diodes (LEDs), edge emitting laser diodes (EELs), vertical cavity surface emitting lasers (VCSELs), and surface emitting diodes. In some embodiments, the light source can produce energy having a wavelength of 830 nm, for example. Various techniques that are known for coupling the light beam 80 into the waveguide 42 may be used. Once the light beam 80 is coupled into the waveguide 42, the light propagates through the waveguide 42 toward a truncated end of the waveguide 42 that is formed adjacent the air bearing surface (ABS) of the recording head 30. Light is focused on the NFT and the energy is transferred from the light to the NFT and subsequently to the media and heats a portion of the media, as the media moves relative to the recording head as shown by arrow 82. A near-field transducer (NFT) 84 is positioned in or adjacent to the waveguide and at or near the air bearing surface. The design may incorporate a heat sink made of a thermally conductive material integral to, or in direct contact with, the NFT 84, and chosen such that it does not prevent coupling of electromagnetic energy into and out of the NFT 84. The heat sink may be composed of a single structure or multiple connected structures, positioned such that they can transfer heat to other metallic features in the head and/or to the gas flow external to the recording head.
Although the example of
Disclosed overcoats include tantalum oxide. The formula of tantalum oxide or tantalum oxides can be given as TayOx with x and y being a number (integer or otherwise). In some embodiments, y can range from 1 or 2; and x can be range from 2 to 5. In some embodiments, y can be 1 or 2; and x can be an integer from 2 to 5. Tantalum oxide exists in various forms, depending on the oxidation state of the tantalum. Tantalum oxide can be described as being tantalum rich (x is higher than y, i.e., fractionally higher) or oxygen rich (y is higher than x, i.e., fractionally higher). Tantalum oxide can also exist as Ta2O5, TaO2, Ta2O3, or combinations thereof. The phrase “tantalum oxide”, when used herein can refer to a single form of tantalum oxide or multiple forms of tantalum oxide. Ta2O5 can be referred to as tantalum pentoxide, tantalum (V) oxide, or ditantalum pentoxide. TaO2 can be referred to as tantalum dioxide, or tantalum (IV) oxide. Ta2O3 can be referred to as ditantalum trioxide, or a suboxide of tantalum. Disclosed overcoats can also include tantalum in addition to one or more forms of tantalum oxide.
An overcoat that includes tantalum oxide can provide advantages. For example, tantalum oxide can provide beneficial thermal properties that can be advantageous if the device is to be utilized in high temperature environments. In some embodiments where disclosed devices can be used as heat assisted magnetic recording (HAMR) heads, thermal resistance at higher temperatures can be advantageous because HAMR heads generate significant heat during operation. For example, a HAMR head can generate or be utilized in environments where the temperature can be as high as 600° C. Previously utilized overcoats such as DLC (diamond-like carbon) can react with oxygen (in the air at the air-bearing surface (ABS)) at these temperatures and leave the writer un-protected. Tantalum oxides, on the other hand, are very stable, even at these high temperatures and will not leave the writer un-protected. It is desirable to protect the writer because an unprotected writer is likely to corrode (react with water and oxygen) and loose its high-moment magnetic properties, rendering it unable to write magnetic bits. Disclosed overcoats can be less likely to be damaged in such high temperature environments. Tantalum oxide can also provide advantageous long term stability that can be advantageous to offer reliability for long term use of a HAMR head.
Contrary to disclosed overcoats, previously utilized overcoats such as DLC (diamond-like carbon) can react with oxygen (in the air at the air-bearing surface (ABS)) at these temperatures (as high as 500° C.) and leave the writer un-protected. Tantalum oxide is stable, even at these high temperatures, and will not leave the writer un-protected. Protection of the writer can be advantageous because an unprotected writer is likely to corrode (react with water and oxygen) and lose its high-moment magnetic properties, rendering it unable to write magnetic bits.
In some embodiments, disclosed overcoats that include tantalum oxide can have thicknesses from 5 Å to 100 Å. The thickness of the overcoat can be considered a balance between protecting the writer (for example) from the corrosive properties of gasses at the ABS and the performance loss due to the increased writer (and reader) to media spacing. In some disclosed embodiments, overcoats of as little as 10 Å can be deposited, such overcoats may seek to minimize performance loss due to the increased writer to media spacing. In some embodiments, disclosed overcoats can have thicknesses from 5 Å to 60 Å. In some embodiments, disclosed overcoats can have thicknesses from 10 Å to 50 Å. In some embodiments, disclosed overcoats can have thicknesses from 30 Å to 50 Å, or in some embodiments 40 Å.
Also disclosed herein are methods of forming articles. Disclosed methods can generally include a step of forming a layer of tantalum oxide on a structure. In some embodiments, the structure upon which the tantalum oxide layer is to be formed can include a magnetic structure. In some embodiments, the magnetic structure can include a magnetic writer. Details of magnetic writers were discussed above. In some embodiments, the magnetic structure can also include a near field transducer (NFT), additional structures for use in HAMR, or some combination thereof. Magnetic structures upon which disclosed overcoat layers are formed can be formed prior to disclosed methods being carried out by the same user or another. Subsequent steps can be included between the formation of the magnetic structure and the overcoat layer. For example, a magnetic structure can be formed on a wafer, the wafer can be cut into bars (including one or more magnetic structures), and the bars can be processed to form heads. Such processing can include steps that are designed to form the ABS (see air bearing surface 56 in
In some embodiments, a tantalum oxide layer can be formed by depositing tantalum (Ta) in an oxygen atmosphere. In some embodiments, “an oxygen atmosphere” refers to a partial pressure of oxygen of approximately 5 mTorr. The Ta can be deposited by sputtering, or physical vapor deposition for example. Deposition of Ta in an oxygen atmosphere can automatically oxidize the Ta as it is being deposited. In some embodiments, a portion of Ta can be deposited in a non-oxygen atmosphere and then another portion of Ta can be deposited in an oxygen atmosphere. Such methods that include an initial step of a non-oxygen atmosphere could be advantageous because it would minimize or eliminate exposure of the magnetic structure (or portions thereof) to an oxygen atmosphere. Some materials present in magnetic structures can be detrimentally affected by an oxygen atmosphere. Such methods could provide an article that has a magnetic structure, at least a partial layer of tantalum, and at least a partial layer of tantalum oxide. In some embodiments, TaxOy can be created by RF sputtering from a TaxOy target. In some embodiments, TaxOy can be created by reactive deposition from a Ta target in an oxygen environment (for example sputtering, evaporation, etc.). In some embodiments, TaxOy can be created by depositing metallic tantalum and then oxidizing it.
In some embodiments, a tantalum oxide layer can be formed by depositing a Ta layer and then subsequently oxidizing at least a part of the Ta layer. The Ta can be deposited for example by sputtering, or physical vapor deposition. The step of oxidizing the deposited Ta can be accomplished, for example, using plasma ashing using oxygen, radical shower, plasma oxidation, O2 exposure, or some combination thereof for example. In some embodiments, the oxidation step can also be combined with a high temperature environment in order to enhance the oxidation (e.g., annealing in an oven, baking with a hot plate, etc.). Plasma ashing using oxygen creates a monoatomic oxygen plasma by exposing oxygen gas at a low pressure to high power radio waves, which ionize it.
In some embodiments, a layer of Ta that is less thick than the desired tantalum oxide layer can be deposited. Once the tantalum layer is oxidized, the final layer will have a thickness that is increased from the original tantalum layer. In some embodiments, the thickness can increase at least 30%, and in some embodiments, the thickness can increase 30% to 40%. In some embodiments, lower power tantalum deposition can help more accurately control the thickness of the final tantalum oxide layer. In some embodiments, lower tantalum deposition at not greater than 300 W can be utilized, and in some embodiments, tantalum deposition at not greater than 200 W can be utilized.
In some embodiments, not all of the Ta need be oxidized. Such methods could be advantageous because it would minimize or eliminate exposure of the magnetic structure (or portions thereof) to an oxygen atmosphere or an oxidized material. Some materials present in magnetic structures can be detrimentally affected by an oxygen atmosphere or oxidized material. Such methods could provide an article that has a magnetic structure, at least a partial layer of tantalum, and at least a partial layer of tantalum oxide.
A sheet of tantalum (14 Å) was deposited using DC magnetron sputtering from a tantalum target.
Thus, embodiments of magnetic devices including overcoat layers are disclosed. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the present disclosure can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.
