Source: https://patents.google.com/patent/US8040761B2/en
Timestamp: 2019-02-17 00:55:23
Document Index: 413462200

Matched Legal Cases: ['art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art 32', 'art\n2', 'Application No. 2009']

US8040761B2 - Near-field light generating device including near-field light generating element disposed over waveguide with buffer layer and adhesion layer therebetween - Google Patents
Near-field light generating device including near-field light generating element disposed over waveguide with buffer layer and adhesion layer therebetween Download PDF
US8040761B2
US8040761B2 US12/457,886 US45788609A US8040761B2 US 8040761 B2 US8040761 B2 US 8040761B2 US 45788609 A US45788609 A US 45788609A US 8040761 B2 US8040761 B2 US 8040761B2
US12/457,886
US20100329085A1 (en
2009-06-24 Application filed by TDK Corp filed Critical TDK Corp
2009-06-24 Priority to US12/457,886 priority Critical patent/US8040761B2/en
2009-06-24 Assigned to TDK CORPORATION reassignment TDK CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AOKI, SUSUMU, ISOGAI, MAKOTO, KAWAMORI, KEITA, KOMURA, EIJI, MIYAUCHI, DAISUKE
2010-12-30 Publication of US20100329085A1 publication Critical patent/US20100329085A1/en
2011-10-18 Publication of US8040761B2 publication Critical patent/US8040761B2/en
A near-field light generating device includes: a waveguide; a buffer layer disposed on the top surface of the waveguide; an adhesion layer that is formed by incompletely oxidizing a metal layer and disposed on the buffer layer; and a near-field light generating element disposed on the adhesion layer. The adhesion layer has a resistance-area product higher than that of the metal layer unoxidized and lower than that of a layer that is formed by completely oxidizing the metal layer. A layered structure consisting of the buffer layer, the adhesion layer and the near-field light generating element has a peel-test adhesive strength higher than that of a layered structure consisting of the buffer layer and the near-field light generating element.
Among known materials of the near-field light generating element that can produce surface plasmon polariton coupling are noble metals such as Ag and Au. For example, Michael Hochberg, Tom Baehr-Jones, Chris Walker & Axel Scherer, “Integrated Plasmon and dielectric waveguides,” OPTICS EXPRESS Vol. 12, No. 22, pp. 5481-5486 (2004), and U.S. Patent Application Publication No. 2005/0249451 A1 describe that a waveguide made of Si and a plasmon waveguide (metal waveguide) made of Ag can produce surface plasmon polariton coupling.
It is an object of the present invention to provide a near-field light generating device and a method of manufacturing the same, the near-field light generating device having a near-field light generating element disposed above a waveguide with a buffer layer and an adhesion layer interposed therebetween, the device being capable of preventing exfoliation of the near-field light generating element and suppressing a drop in the use efficiency of light propagating through the waveguide resulting from the adhesion layer, and to provide a heat-assisted magnetic recording head, a head gimbal assembly and a magnetic recording device each of which includes the near-field light generating device.
The “layer that is formed by completely oxidizing a metal layer” refers to a layer that is entirely composed of an oxide of the metal that constitutes the metal layer. In contrast, the “adhesion layer that is formed by incompletely oxidizing a metal layer” according to the present invention is not entirely composed of an oxide of the metal that constitutes the metal layer but contains both the oxide of the metal that constitutes the metal layer and the metal that constitutes the metal layer. The “adhesion layer that is formed by incompletely oxidizing a metal layer,” the “layer that is formed by completely oxidizing the metal layer,” and the “metal layer unoxidized” are distinguishable from each other by comparing the values of their resistance-area products.
FIG. 1 is a perspective view of a near-field light generating device according to an embodiment of the invention.
A preferred embodiment of the present invention will now be described in detail with reference to the drawings. Reference is first made to FIG. 7 to describe a magnetic disk drive as a magnetic recording device according to the embodiment of the invention. As shown in FIG. 7, the magnetic disk drive includes a plurality of magnetic disks 201 as a plurality of magnetic recording media, and a spindle motor 202 for rotating the plurality of magnetic disks 201. The magnetic disks 201 of the present embodiment are for use in perpendicular magnetic recording. Each magnetic disk 201 has such a structure that a soft magnetic backing layer, a middle layer and a magnetic recording layer (perpendicular magnetization layer) are stacked in this order on a disk substrate.
The slider 10 includes a slider substrate 11 and a head unit 12. The slider substrate 11 is rectangular-solid-shaped and is made of a ceramic material such as aluminum oxide-titanium carbide (Al2O3—TiC). The slider substrate 11 has a medium facing surface 11 a that faces the magnetic disk 201, a rear surface 11 b opposite to the medium facing surface 11 a, and four surfaces connecting the medium facing surface 11 a to the rear surface 11 b. One of the four surfaces connecting the medium facing surface 11 a to the rear surface 11 b is an element-forming surface 11 c. The element-forming surface 11 c is perpendicular to the medium facing surface 11 a. The head unit 12 is disposed on the element-forming surface 11 c. The medium facing surface 11 a is processed so as to obtain an appropriate flying height of the slider 10 with respect to the magnetic disk 201. The head unit 12 has a medium facing surface 12 a that faces the magnetic disk 201, and a rear surface 12 b opposite to the medium facing surface 12 a. The medium facing surface 12 a is parallel to the medium facing surface 11 a of the slider substrate 11.
For the components of the head unit 12, with respect to a reference position, a position located in a direction that is perpendicular to the element-forming surface 11 c and gets away from the element-forming surface 11 c is defined as “above”, and a position located in a direction opposite to the above-mentioned direction is defined as “below”. For any of the layers included in the head unit 12, the surface closer to the element-forming surface 11 c is defined as a “bottom surface,” and the surface farther from the element-forming surface 11 c as a “top surface.”
The light source unit 50 includes a laser diode 60 serving as a light source for emitting laser light, and a rectangular-solid-shaped support member 51 that supports the laser diode 60. The support member 51 is made of, for example, a ceramic material such as aluminum oxide-titanium carbide (Al2O3—TiC). The support member 51 has a bonding surface 51 a, a rear surface 51 b opposite to the bonding surface 51 a, and four surfaces connecting the bonding surface 51 a to the rear surface 51 b. One of the four surfaces connecting the bonding surface 51 a to the rear surface 51 b is a light-source-mounting surface 51 c. The bonding surface 51 a is the surface to be bonded to the rear surface 11 b of the slider substrate 11. The light-source-mounting surface 51 c is perpendicular to the bonding surface 51 a and parallel to the element-forming surface 11 c. The laser diode 60 is mounted on the light-source-mounting surface 51 c. The light-source-mounting surface 51 c corresponds to the top surface of the support member of the present invention. The support member 51 may have the function of a heat sink for dissipating heat generated by the laser diode 60, in addition to the function of supporting the laser diode 60.
The waveguide 31 extends in the direction perpendicular to the medium facing surface 12 a (the X direction). The waveguide 31 has: the incidence end 31 a shown in FIG. 10; an end face 31 b closer to the medium facing surface 12 a; a top surface 31 c; a bottom surface 31 d; and two side surfaces 31 e and 31 f. The bottom surface 31 d is in contact with the top surface of the dielectric layer 27. The dielectric layer 29 disposed around the waveguide 31 has a top surface 29 c. The end face 31 b may be located in the medium facing surface 12 a or away from the medium facing surface 12 a. FIG. 1 to FIG. 6 show the case where the end face 31 b is located away from the medium facing surface 12 a. In this case, a part of the dielectric layer 29 is interposed between the end face 31 b and the medium facing surface 12 a. The waveguide 31 allows propagation of laser light 35 that is emitted from the laser diode 60 and incident on the incidence end 31 a.
As shown in FIG. 1 to FIG. 3, the top surface 31 c of the waveguide 31 has a groove 31 g that is long in a first direction. The first direction is parallel to the X direction. As shown in FIG. 2, the groove 31 g has first and second groove sidewalls 31 g 1 and 31 g 2 that decrease in distance from each other toward the element-forming surface 11 c.
As shown in FIG. 1, in the case where the end face 31 b of the waveguide 31 is located away from the medium facing surface 12 a, the top surface 29 c of the dielectric layer 29 has a groove 29 g that is located in the area between the end face 31 b of the waveguide 31 and the medium facing surface 12 a and that extends in the first direction (the X direction) so as to be contiguous to the groove 31 g. The cross section of the groove 29 g parallel to the medium facing surface 12 a has the same shape as the cross section of the groove 31 g parallel to the medium facing surface 12 a. The groove 29 g does not exist if the end face 31 b of the waveguide 31 is located in the medium facing surface 12 a.
As shown in FIG. 1 and FIG. 2, the clad layer 34 has a bottom surface 34 a, a top surface 34 b, and an opening 34 c. The bottom surface 34 a is in contact with the top surface 31 c of the waveguide 31 and the top surface 29 c of the dielectric layer 29. The top surface 34 b is opposite to the bottom surface 34 a. The opening 34 c penetrates the clad layer 34 from the top surface 34 b to the bottom surface 34 a and is contiguous to the grooves 31 g and 29 g. As shown in FIG. 2, the opening 34 c has first and second opening sidewalls 34 c 1 and 34 c 2 that decrease in distance from each other toward the top surface 31 c of the waveguide 31. The first groove sidewall 31 g 1 is contiguous to the first opening sidewall 34 c 1. The second groove sidewall 31 g 2 is contiguous to the second opening sidewall 34 c 2.
The near-field light generating element 32 further has an edge part 32 f and a near-field light generating part 32 g. The edge part 32 f connects the first and second side surfaces 32 d and 32 e to each other, and is opposed to the groove 31 g with the buffer layer 33 and the adhesion layer 38 therebetween. The near-field light generating part 32 g is located in the medium facing surface 12 a and generates near-field light. The near-field light generating part 32 g lies at one end of the edge part 32 f that is located in the medium facing surface 12 a. Specifically, the near-field light generating part 32 g refers to the end of the edge part 32 f in the end face 32 a and its vicinity. As shown in FIG. 2, the angle formed between the first side surface 32 d and the second side surface 32 e will be denoted by the symbol θ. The angle θ falls within the range of 80° to 120°, for example.
As previously mentioned, possible shapes of the near-field light generating element 32 are not limited to a triangular prism shape. For example, the near-field light generating element 32 may be tetragonal-prism-shaped. In this case, the cross section of the near-field light generating element 32 parallel to the medium facing surface 12 a may be rectangular, or may be trapezoidal such that the width decreases toward the element-forming surface 11 c.
An example of the configuration of the magnetic pole 42 will now be described with reference to FIG. 3 to FIG. 5. In this example, the magnetic pole 42 includes a first layer 42A, a second layer 42B and a third layer 42C. As shown in FIG. 4, the first layer 42A has an end face that is located in the medium facing surface 12 a at a position forward of the first end face 32 a of the near-field light generating element 32 along the Z direction (in other words, located closer to the trailing end). The distance between this end face of the first layer 42A and the first end face 32 a preferably falls within the range of 20 to 50 nm. The second layer 42B is disposed on the first layer 42A and touches the top surface of the first layer 42A. The second layer 42B has an end face that is closer to the medium facing surface 12 a, and this end face is located at a distance from the medium facing surface 12 a. The third layer 42C is disposed on the second layer 42B and touches the top surface of the second layer 42B. The third layer 42C has an end face that is closer to the medium facing surface 12 a, and this end face is located at a distance from the medium facing surface 12 a. The distance between the end face of the third layer 42C and the medium facing surface 12 a is greater than the distance between the end face of the second layer 42B and the medium facing surface 12 a.
Next, an example of the configuration of the write shield 43 will be described with reference to FIG. 5 and FIG. 10. In this example, the write shield 43 includes a first layer 43A and a second layer 43B. As shown in FIG. 5, the first layer 43A is separated from the magnetic pole 42 by the gap layer 44 and disposed between the medium facing surface 12 a and the respective end faces of the second layer 42B and the third layer 42C of the magnetic pole 42. As shown in FIG. 10, the second layer 43B is disposed on the first layer 43A, the insulating layer 47 and the third layer 42C of the magnetic pole 42. A part of the second layer 43B located near the medium facing surface 12 a touches the top surface of the first layer 43A, and another part of the second layer 43B located away from the medium facing surface 12 a touches the top surface of the third layer 42C.
Next, as shown in FIG. 13, the buffer layer 33 is formed in the groove 31 g, the groove 29 g (only where it exists) and the opening 34 c.
Next, as shown in FIG. 14, a metal layer 38P, which is intended to make the adhesion layer 38 when incompletely oxidized afterward, is formed on the buffer layer 33 by sputtering, for example. If a layer formed by incompletely oxidizing a metal layer made of Ti, Ta, Sn, or an alloy containing at least one of Ti, Ta and Sn as a main component is intended to be the adhesion layer 38, then the metal layer 38P is formed of Ti, Ta, Sn, or an alloy containing at least one of Ti, Ta and Sn as a main component.
Forming method for Resistance-area Real Imaginary
Sample adhesion layer product (Ω-μm2) part part
2 1.0-nm Ti layer intact 0.1 2.2 3.0
3 Incompletely oxidizing 1.1 2.5 1.7
4 Completely oxidizing 50 2.9 0.0
In the first experiment, the adhesive strengths of samples 1 to 4 were evaluated by three tests, i.e., a peel test, a scratch test and a shear test. The peel test was performed as described below according to a cross cut method. Initially, lattice-like cuts to reach the buffer layer 33 were made in each sample from the Ag-layer side so as to form 25 square areas of 5 mm×5 mm. Next, an adhesive tape was applied to the Ag layer of the sample thus having the cuts, and then the adhesive tape was peeled off. The 25 areas of the sample were checked for the number of areas where no exfoliation occurred at an interface between any two of the layers. The adhesive tape used was one having an adhesion to the Ag layer clearly higher than the adhesion between the buffer layer 33 and the Ag layer in sample 1.
The following Table 2 shows the results of the foregoing three tests performed on samples 1 to 4. In Table 2, the denominator of the “number of remaining films” in the peel test shows the number of areas (25) formed in the sample, and the numerator of the “number of remaining films” shows the number of areas where no exfoliation occurred at an interface between any two of the layers out of the 25 areas. In Table 2, “exfoliation” in the scratch test refers to exfoliation at an interface between any two of the layers in the sample.
Peel test Shear test
Number of Scratch Exfoliation
Sample Adhesion layer remaining films test strength
1 None 0/25 Exfoliation approx. 4 gf
2 1.0-nm Ti layer 25/25 No approx. 32 gf
3 1.0-nm Ti layer 25/25 No approx. 25 gf
incompletely exfoliation
4 1.0-nm Ti layer 8/25 Exfoliation approx. 14 gf
Sample Adhesion layer remaining films Scratch test
5 1.0-nm Ta layer 25/25 No exfoliation
6 1.0-nm Ta layer 25/25 No exfoliation
7 1.0-nm Ta layer 0/25 Exfoliation
8 1.0-nm Sn layer 25/25 No exfoliation
Model Adhesion layer Light use efficiency
1 None 100
2 1.5-nm Ti layer 68.2
3 1.0-nm Ti layer 75.6
4 1.0-nm Ti layer 84.8
5 1.0-nm Ti layer 90.3
6 None 100
7 1.5-nm Ti layer 71
8 1.0-nm Ti layer 75
9 1.0-nm Ti layer 84
10 1.0-nm Ti layer 87
In the foregoing embodiment, the end face of the magnetic pole 42 (the end face of the first layer 42A) is located in the medium facing surface 12 a at a position forward of the end face 32 b of the near-field light generating element 32 along the Z direction (in other words, located closer to the trailing end). However, the end face of the magnetic pole 42 may be located backward of the end face 32 b of the near-field light generating element 32 along the Z direction (in other words, located closer to the leading end) in the medium facing surface 12 a.
a positioning device that supports the heat-assisted magnetic recording head and positions the heat-assisted magnetic recording head with respect to the magnetic recording medium.
US12/457,886 2009-06-24 2009-06-24 Near-field light generating device including near-field light generating element disposed over waveguide with buffer layer and adhesion layer therebetween Active 2030-04-09 US8040761B2 (en)
US12/457,886 US8040761B2 (en) 2009-06-24 2009-06-24 Near-field light generating device including near-field light generating element disposed over waveguide with buffer layer and adhesion layer therebetween
JP2009291784A JP2011008899A (en) 2009-06-24 2009-12-24 Near-field light generating device and method of manufacturing the same
US20100329085A1 US20100329085A1 (en) 2010-12-30
US8040761B2 true US8040761B2 (en) 2011-10-18
ID=43380594
US12/457,886 Active 2030-04-09 US8040761B2 (en) 2009-06-24 2009-06-24 Near-field light generating device including near-field light generating element disposed over waveguide with buffer layer and adhesion layer therebetween
US (1) US8040761B2 (en)
JP (1) JP2011008899A (en)
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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KAWAMORI, KEITA;ISOGAI, MAKOTO;AOKI, SUSUMU;AND OTHERS;REEL/FRAME:022899/0671