Method for fabricating a magnetic recording device having a high aspect ratio structure

Description

BACKGROUND

FIG. 1 depicts an air-bearing surface (ABS) view of a conventional magnetic recording transducer 10 during formation. The magnetic recording transducer 10 may be a perpendicular magnetic recording (PMR) head or a heat assisted magnetic recording (HAMR) head. The conventional transducer 10 includes an underlayer 12 on which a photoresist mask 14 has been formed. During formation of the photoresist mask 14, a bottom antireflective coating 16 has been used. The photoresist mask 15 has an aperture in which the pole 20 is formed. The pole 20 has pole sidewalls 22 and 24 having a shape that matches the sidewalls of the aperture in the photoresist mask 14. As can be seen in FIG. 1, the main pole 20, and photoresist mask 14, have a width d1 at the bottom of the trench and a height d2. The aspect ratio of the main pole 20, the height of the main pole/aperture and divided by the width at the bottom (d2/d1) is desired to be large.

Although the conventional magnetic recording head 10 functions, there are drawbacks. In particular, the sidewalls 22 and 24 of the main pole 20 may not be vertical. Particularly for a main pole 20 having a high aspect ratio of greater than five, the top of the aperture, and thus the main pole 20, may be noticeably wider than the bottom. In addition, the sidewall angle changes near the top of the pole, as depicted in FIG. 1. This issue is exacerbated at lower pole widths, such as on the order of two hundred nanometer or less. Such low width poles may be formed by trimming the main pole 20. However, it in some cases, such an operation is undesirable. Accordingly, what is needed is a system and method for improving the performance of a magnetic recording head.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts an ABS view of a conventional magnetic recording head.

FIG. 2 depicts a flow chart of an exemplary embodiment of a method for providing a magnetic recording transducer having a high aspect ratio structure.

FIGS. 3-6 depict ABS views of an exemplary embodiment of a magnetic write apparatus during fabrication.

FIG. 7 depicts a flow chart of another exemplary embodiment of a method for providing half side shields.

FIGS. 8 through 14 depict views of an exemplary embodiment of a magnetic recording transducer fabricated using the method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 depicts an exemplary embodiment of a method 100 for providing a magnetic recording device such as a magnetic recording transducer. For simplicity, some steps may be omitted, interleaved, combined and/or performed in another order. FIGS. 3-6 depict views of an exemplary embodiment of a magnetic recording apparatus 200 during fabrication. FIGS. 3-6 are not to scale. The method 100 is described in the context of providing a magnetic recording transducer 200 depicted in FIGS. 3-6. However, the method 100 may be used to fabricate multiple magnetic recording devices at substantially the same time. The method 100 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 100 also may start after formation of other portions of the magnetic recording apparatus. In some embodiments, the method 100 may be used to form a pole in a heat assisted magnetic recording (HAMR) writer. In other embodiments, other structures and/or other magnetic recording devices may be fabricated.

A mask is provided on a substrate, via step 102. The substrate may be considered to be any layers underlying the structure that is desired to be formed. For example, if the structure being formed is a pole in a HAMR transducer, then the substrate may include the underlying slider, read transducer (if any), waveguides and other optics such as a near-field transducer (NFT). The mask provided in step 102 has a trench therein. The trench has a top, a bottom and sidewalls extending between the top and the bottom of the trench. The top of the trench is wider than the bottom. In some embodiments, step 102 includes depositing a bottom antireflective coating (BARC) layer on the substrate, providing a photoresist layer on the BARC layer and selectively exposing a portion of the photoresist layer to light. A portion of the photoresist layer may also be removed in step 102. A remaining portion of the photoresist layer forms the mask.

FIG. 3 depicts the magnetic recording apparatus 200 after step 102 is performed. Thus, a mask 204 on the underlayer 202 is shown. The underlayer 202 may be considered part of the substrate discussed above. In the HAMR transducer example above, the underlayer 202 may include cladding for a waveguide. In some embodiments, the mask 204 is a photoresist mask. The mask 204 includes a trench 206 having sidewalls 208. The trench 206 has a height, h and a width, w. In some embodiments, the aspect ratio of the trench (h/w) is at least four. In some embodiments, the aspect ratio of the trench 206 is at least five. Also in some embodiments, the width of the trench 206 at the bottom is less than three hundred nanometers (w<300 nm). In some embodiments, the width of the bottom of the trench 206 is two hundred nanometers or less. The height of the photoresist mask may be at least one micron. In other embodiments, other widths and/or aspect ratios are possible. As can be seen in FIG. 3, the top of the trench is wider than the bottom.

A protective layer is provided in the trench 206, via step 104. The protective layer extends from the top of the trench 206 along a portion of the sidewalls 208. However, the bottom of the trench 206 and a second portion of the sidewalls 208 near the bottom are free of the protective layer. In some embodiments, step 104 includes providing a protective layer including amorphous carbon. In other embodiments, the protective layer consists of amorphous carbon. In some embodiments, step 104 includes blanket depositing a film for the protective layer and anisotropically removing a portion of the film. Such an anisotropic removal process tends to remove more material on the surfaces parallel to the top of the mask 204. As a result, a portion of the protective layer film near the bottom of the trench 206 and on the top surface of the mask 204 may be removed.

FIG. 4 depicts the magnetic apparatus 200 after step 104 is performed. Thus, the protective layer 210 is present. The protective layer 210 resides at the top of the trench 206. Near the bottom, however, the mask 204 is exposed. As a result, the sidewalls of the remaining portion of the trench 206 may be substantially vertical and linear.

The desired structure is provided in the open portion of the trench 206, via step 106. Step 106 may include plating high saturation magnetization material(s) for a pole and/or otherwise depositing material(s) for the structure being formed. A planarization step may also be performed. After formation of the structure is completed, the mask 204 may be removed.

FIG. 5 depicts the write apparatus 200 during step 106. Thus, the structure 220 is formed. Because of the presence of the protective layer 210, the sidewalls of the structure 220 are substantially vertical. In addition, the aspect ratio of the structure 220 may be h/w, substantially the same as the remaining portion of the trench 206. FIG. 6 depicts the magnetic recording apparatus 200 after removal of the mask 200. Thus, a structure 220 having a large aspect ratio and small width has been formed.

Using the method 100, a magnetic recording apparatus having improved performance may be fabricated. In particular, a structure 220 having a small width described above and a large height may be formed. For example, the width of the structure 220 may be two hundred nanometers or less. The height of the structure may be one micron or more. Further, the sidewalls 222 of the structure 220 may be substantially straight and vertical (e.g. perpendicular to the top surface of the underlayer/substrate 202). Thus, the desired geometry of the structure 220 may be obtained. Further, this is achieved with little or no trimming of the structure 220. A trim uses a removal process, such as an anisotropic etch, that removes more material in the vertical direction parallel to the height h. In such a process, a large portion of the underlayer 202 adjacent to the structure 220 may be removed. Thus, underlying structures may be damaged. Use of the method 100 may allow for a high aspect ratio/small width structure 220 to be formed without requiring a trim process. Underlying structures, such as waveguides or other features, need not be damaged. Consequently, fabrication and performance of the magnetic recording apparatus 200 may be improved.

FIG. 7 depicts an exemplary embodiment of a method 150 for providing a structure such as a write pole for a magnetic recording device. For simplicity, some steps may be omitted, interleaved, performed in another order and/or combined. FIGS. 8-14 depict various views of an exemplary embodiment of a magnetic recording transducer 250 during fabrication. For clarity, FIGS. 8-14 are not to scale. The method 150 is described in the context of providing a single magnetic recording transducer 250 depicted in FIGS. 8-14. Referring to FIGS. 7-14, the method 150 may be used to fabricate multiple magnetic recording heads at substantially the same time. The method 150 may also be used to fabricate other magnetic recording transducers or other devices. The method 150 is also described in the context of particular layers. A particular layer may include multiple materials and/or multiple sub-layers. The method 150 also may start after formation of other portions of the magnetic recording transducer. For example, the method 150 may start after a read transducer, return pole/shield and/or other structure have been fabricated. In some embodiments, the method 150 is used to fabricate a write pole for a HAMR transducer.

A BARC layer is provided on the substrate, via step 152. Step 152 may include depositing a material, such as amorphous carbon, with the appropriate thickness for the light being used in fabrication of the photoresist mask. For example, in some embodiments, an amorphous carbon BARC layer that is nominally three hundred Angstroms thick might be used. In other embodiments, other materials might be used for the BARC layer. For example, SiN might be combined with amorphous carbon when a pole is being fabricated. SiN might be used alone for other structures.

A photoresist layer is provided, via step 154. For example, the photoresist might be spin coated or otherwise deposited on the device being fabricated. FIG. 8 depicts an ABS view of the transducer 250 after step 154 is completed. Thus, the BARC 253 and photoresist layer 254 are shown on an underlayer/substrate 252. In some embodiments, the height, h, of the photoresist layer 254 is at least one micron. In some embodiments, the photoresist layer 254 may be 1.5 micron or more thick.

Selected portions of the photoresist layer 254 are exposed to light, via step 156. The photoresist layer 254 is then exposed to developer and a portion of the photoresist layer removed, via step 158. Thus, a photoresist mask is formed. FIG. 9 depicts the transducer 250 after step 156 is performed. Thus, a trench 256 having sidewalls 258 is formed in the photoresist mask 254′. As can be seen in FIG. 9, the sidewalls 258 are not vertical.

A protective layer film is deposited, via step 160. Step 160 may include depositing an amorphous carbon layer. FIG. 10 depicts the transducer 250 after step 160 is performed. Thus, a protective layer film 260 has been deposited. In some embodiments, the thickness of the protective film 260 is at least one nanometer thick and not more than eight nanometers thick. In some such embodiments, the protective layer film 260 is at least two nanometers and not more than five nanometers thick. However, other thicknesses are possible. As can be seen in FIG. 10, the top of the remaining portion of the trench 256 may now be smaller than the bottom. The protective layer film 260 is desired to protect the photoresist mask from removal during a subsequent etch step 162. In some embodiments, the protective layer film 260 includes amorphous carbon. In other embodiments, the protective layer consists of amorphous carbon.

The BARC layer 253 at the bottom of the trench 256 is removed, via step 162. Step 162 may be performed by carrying out an anisotropic reactive ion etch in a forming gas, such as N₂H₂. Such an anisotropic removal process tends to remove more material on the surfaces parallel to the top of the photoresist mask 254′. As a result, a portion of the protective layer film 260 at the top of the photoresist mask 254′ may be removed. The portion of the BARC layer 253 exposed in the trench 256 is also removed.

FIG. 11 depicts the transducer 250 after step 162 is performed. Thus, a protective layer 260′ remains inside the trench 256′. The remaining (e.g. open) portion of the trench 256′ may have substantially vertical sidewalls. Thus, an increase in the width of the top of the trench 256′ is avoided. In addition, the BARC 253′ within the trench 256′ has been removed. The remaining BARC layer 253′ is covered by the photoresist mask 254′.

The layer(s) for the main pole are deposited, via step 164. In some embodiments, step 164 may include plating the main pole material(s). Because the BARC layer 253 at the bottom of the trench 256′ has been removed, plating may be better performed. FIG. 12 depicts the transducer 250 after step 164 has been performed. Thus the pole materials 270 fill the remaining portion of the trench. However, the pole material(s) 270 extend outside of the trench 256′. Consequently, a planarization step, such as a chemical mechanical planarization (CMP) is performed, via step 166. The photoresist mask 254′ may then be removed, via step 168. FIG. 13 depicts the transducer 250 after step 168 is performed. Because of the presence of the protective layer 260′, the sidewalls of the pole 270′ are substantially vertical. In addition, the aspect ratio of the structure 270 may be h/w, substantially the same as the remaining portion of the trench 206. Thus, the main pole 270 having a large aspect ratio and small width has been formed. FIG. 14 depicts a side view of a HAMR disk drive in which the main pole 270 being formed using the method 150 may reside. The HAMR disk drive includes a media 272, the transducer 250, a slider 280 and a laser subassembly 290. The laser subassembly 290 may include a laser 292 and a submount 294 for mechanical stability. The HAMR transducer 250 includes the main pole 270 as well as a waveguide 276, NFT 272 and coil(s) that energize the main pole 270.

Using the method 150, a magnetic transducer such as the HAMR transducer 250 having improved performance may be fabricated. In particular, a main pole 270 having a small width described above and a large height may be formed. For example, the width of the main pole 270 may be two hundred nanometers or less. The height of the main pole 270 may be one micron or more. Further, the sidewalls of the main pole 270 may be substantially straight and vertical (perpendicular to the top surface of the underlayer/substrate 252). Thus, the desired geometry of the main pole 270 may be obtained. Further, this is achieved with little or no trimming of the main pole 270. Thus, damage to the underlying NFT 272, waveguide 276 and/or other structures may be avoided. Consequently, fabrication and performance of the magnetic recording transducer 250 may be improved.