JP4038437B2 - Magnetic head slider and magnetic disk apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head slider structure for realizing a high recording density of a magnetic disk device, and more particularly to a flying height adjustment slider having a function of adjusting a distance between a magnetic disk and a magnetic head.
[0002]
[Prior art]
The magnetic disk device has a rotating magnetic disk and a magnetic head slider (also referred to simply as a slider) mounted with a recording / reproducing element and supported by a load beam and positioned in the radial direction, and the slider relatively runs on the magnetic disk. The magnetic information recorded on the magnetic disk is read and written. The slider floats as an air-lubricated bearing by the wedge film effect of air so that the magnetic disk and the slider are not in direct solid contact. In order to increase the recording density of a magnetic disk device and increase the capacity or size of the device, it is effective to increase the linear recording density by reducing the distance between the slider and the magnetic disk, that is, the slider flying height. is there.
[0003]
Conventionally, in the design of the slider flying height, a flying height margin has been provided so that the slider and the disk do not come into contact with each other even in the worst conditions, with the expectation that the flying height will decrease due to processing variations, operating environment pressure differences, operating environment temperature differences, and the like. If a slider with a function to adjust the flying height according to the individual head or according to the usage environment is realized, the above margin can be eliminated, and the flying height of the recording / reproducing element is greatly increased while preventing contact between the slider and the disk. Can be shortened. For example, there has been proposed a slider structure in which a heating device composed of a thin film resistor is provided in the vicinity of a recording / reproducing element, and a part of the slider is heated as necessary to thermally expand and protrude to adjust the flying height of the recording / reproducing element. (For example, refer to Patent Document 1).
[Patent Document 1]
JP-A-5-20635 (page 3).
[0004]
[Problems to be solved by the invention]
First, there is a problem of the read element life. A reproducing element using the magnetoresistive effect (MR effect), which is currently in the mainstream, has a feature that it is weak against heat load and has a short life if exposed to a high temperature for a long time. The method disclosed in Japanese Patent Application Laid-Open No. 5-20635 is an effective flying height adjustment method. However, when it is applied to the current recording / reproducing element, the thin film resistor as a heating device is positioned very close to the recording / reproducing element. Therefore, there is a possibility that the life of the reproducing element is reduced by heating.
[0005]
Secondly, there is a problem of the flying height adjustment direction. Since the system disclosed in the publication is a system in which the recording / reproducing element portion is protruded by thermal expansion, the flying height is reduced by energization. Regarding the atmospheric pressure (operating altitude), the flying height tends to increase at high pressure (low altitude) where the pressure applied to the air bearing is large, and the flying height tends to decrease as the pressure decreases (high altitude). Therefore, it is necessary to design a floating surface that does not contact even at high altitudes, and to always lower the flying height by energizing in low altitudes. However, it is more frequently used in low altitudes than in high altitudes, so it was indicated in the same publication. The amount of power required for the flying height adjustment direction is larger than that for the opposite direction.
[0006]
In summary, the present invention aims to solve these two problems: reducing the thermal load on the reproducing element and developing an adjustment method in the direction of increasing the flying height by energization.
[0007]
[Means for Solving the Problems]
The above-mentioned problems are: firstly, the thin film resistor, which is a heating device, is sufficiently separated from the recording / reproducing element, and secondly, the air pressure generated on the air bearing surface increases due to a part of the air bearing surface protruding when the resistor is energized. Thus, designing the air bearing surface is solved by these two points.
Regarding the first point, the thin film resistor needs to be separated from the recording / reproducing element by 0.1 mm or more. When the recording / reproducing element is at the center of the air outflow end, a thin film resistor is preferably provided at least 0.1 mm apart on both sides of the recording / reproducing element near the outflow end.
Regarding the second point, the air bearing surface of the two-step step bearing slider currently widely used in the industry has three substantially parallel surfaces, that is, (1) a rail surface on which a recording / reproducing element is installed, (2 ) It is composed of a shallow groove surface that is a step bearing, and (3) a deep groove surface that is a negative pressure pocket, but in recent years, the rail surface is the uppermost surface (referred to as an element installation surface) on which a recording / reproducing element is installed, A three-step step bearing slider is newly proposed which is divided into two surfaces of a very shallow step bearing surface (referred to as an ultra-shallow groove surface) of about 5 nm to 50 nm, and the air bearing surface is composed of a total of four parallel surfaces. Yes. The three-step slider has a small and narrow element installation surface, and an ultra-shallow groove surface slightly lower than the element installation surface around it. It can be guaranteed that the distance is close and contributes to a low flying height of the recording / reproducing element. Further, even if the element installation surface is reduced, the super shallow groove surface generates air pressure and supports the load, so that the followability to the micro waviness of the disk is not impaired.
The thin film resistor is exposed to the surface of the air bearing surface or formed at a position having a certain distance in the normal direction from the air bearing surface. If the position where the thin film resistor is projected onto the air bearing surface is in or near the ultra-shallow groove surface area, the super-shallow groove surface will be on the disk side when the thin-film resistor is energized and heated to thermally expand the surroundings. When the air pressure generated on the ultra-shallow groove surface increases, the flying height of the entire slider and the flying height of the recording / reproducing element increase. That is, the flying height adjustment in a direction in which the flying height increases by energization.
By the means described so far, it is possible to realize the flying height adjustment with low power consumption without affecting the life of the reproducing element. As a result, the flying height margin can be eliminated by adjusting the flying height for each individual head or according to the usage environment, and the flying height of the recording / reproducing element is greatly reduced while preventing contact between the slider and the disk. This contributes to an increase in recording density on the magnetic disk surface, and further to an increase in capacity or size of the apparatus.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
A magnetic head slider and a magnetic disk apparatus using the same according to an embodiment of the present invention will be described below with reference to the drawings.
[0009]
A schematic configuration of a magnetic disk apparatus according to an embodiment of the present invention is shown in FIG. The magnetic head slider 1 is equipped with a recording / reproducing element for recording / reproducing magnetic information. The magnetic disk 10 stores magnetic information and is rotated by a spindle motor. The magnetic head slider 1 is attached to a leaf spring-shaped load beam, and a pressing load is applied to the magnetic disk surface by the load beam, and seek operation is performed in the radial direction of the magnetic disk 10 by the voice coil motor together with the load beam. Recording and playback are performed on the entire magnetic disk surface. The magnetic head slider 1 is retracted from the magnetic disk 10 onto the ramp 14 when the apparatus is stopped or when there is no read / write command for a predetermined time.
Here, an apparatus having a load / unload mechanism is shown. However, even in a contact start / stop type magnetic disk apparatus in which the magnetic head slider 1 stands by in a specific area of the magnetic disk 10 while the apparatus is stopped. The effects of the invention can be obtained similarly.
[0010]
FIG. 2 is a perspective view of the slider showing the first embodiment of the present invention. The slider 1 has a substrate (wafer) portion 1a of a material typified by a sintered body of alumina and titanium carbide, a recording / reproducing element and a wiring pattern formed on the substrate by a thin film process, and covered with a hard protective film such as alumina. It consists of a thin film head portion 1b.
[0011]
The slider 1 has a substantially rectangular parallelepiped shape with a length of 1.25 mm, a width of 1.0 mm, and a thickness of 0.3 mm, and a total of 6 on the air bearing surface 9, the air inflow end surface 12, the air outflow end surface 13, both side surfaces, and the back surface. Consists of faces. The air bearing surface 9 is provided with fine steps by processes such as ion milling and etching, and functions as an air bearing that generates air pressure opposite to the disk 10 (not shown) and supports the load applied to the back surface. Plays.
[0012]
The air bearing surface 9 is provided with a step as described above, and is classified into four types of substantially parallel surfaces. The element mounting surface 5 closest to the disk, the ultra-shallow groove surface 6 that is approximately 5 nm deeper than the element mounting surface, the shallow groove surface 7 that is a step bearing surface approximately 150 nm deeper than the element mounting surface, and the deep groove that is approximately 1 μm deeper than the element mounting surface There are four types of surface 8. As shown in the figure, the element installation surface 5, the ultra shallow groove surface 6, and the shallow groove surface 7 are divided into a plurality of components 5a, 5b, 5c, components 6a, 6b, and components 7a, 7b, respectively. FIG. 3 shows an enlarged view of the vicinity of the center on the outflow end side of the air bearing surface. Moreover, the figure seen from the air outflow end side is shown in FIG. In FIG. 4, D1, D2, and D3 are about 5 nm, about 150 nm, and 1 μm, respectively.
[0013]
When the air flow generated by the rotation of the magnetic disk 10 enters from the shallow groove surface 7 which is a step bearing into the element installation surface 5 which is a rail surface and the super shallow groove surface 6, the flow path is tapered. Compressed, producing positive air pressure. On the other hand, when the air flow enters the deep groove surface 8 from the rail surface or the shallow groove surface, a negative air pressure is generated due to the expansion of the flow path.
[0014]
The magnetic head slider 1 is designed to fly in such a posture that the flying height on the air inflow end 12 side is larger than the flying height on the air outflow end side 13. Therefore, the air bearing surface near the outflow end is closest to the disk 10. In the vicinity of the outflow end, the element installation surface 5a protrudes from the surrounding super shallow groove surfaces 6a, 6b, shallow groove surface 7a, and deep groove surface 8, so that the slider pitch posture and the roll posture do not tilt beyond a certain limit. As long as the element mounting surface 5 a is closest to the magnetic disk 10. The magnetic head (consisting of the recording element 2 and the reproducing element 3) is formed on the thin film head portion of the element installation surface 5a. At least the element installation surface 5a is coated with a protective film such as carbon in order to prevent corrosion of the recording / reproducing element.
[0015]
The method of forming a step of about 5 nm between the element installation surface 5 and the ultra-shallow groove surface 6 is an easy method to obtain by removing the carbon film of about 5 nm by means such as oxygen ashing.
[0016]
On the thin film head portions of the ultra-shallow groove surfaces 6a and 6b, heating devices 4a and 4b using thin film resistors are formed using a thin film process. Although the heating devices 4a and 4b have been shown to be exposed on the air bearing surface, they may be separated from the air bearing surface by a certain distance. In this embodiment, the thin film resistor was made of a permalloy material, a thickness of 0.5 mm, and a width of 3 μm meandering in a region having a depth of 60 μm and a width of 60 μm, and the gap was filled with alumina to form a heating element.
[0017]
The feature of this embodiment over the prior art is that the distance D from the reproducing element 3 to the heating device 4a or 4b is 0.1 mm or more. Further, the positions of the heating devices 4a and 4b (or the positions projected on the air bearing surface) are not the element installation surface 5a but the ultra-shallow groove surfaces 6a and 6b.
[0018]
The purpose of the heating device is to adjust the spacing between the recording / reproducing element and the magnetic disk by thermal expansion and deformation, thereby eliminating the flying height margin. In recent years, since the flying height margin is designed to be 10 nm or less, it is sufficient that the flying height change amount is 10 nm at the maximum. Assuming that the relationship between the thermal expansion deformation amount and the flying height change amount is 1: 1, it is sufficient that the thermal expansion deformation amount is also 10 nm. According to the results of head heat transfer analysis and head deformation analysis due to heat generation from the thin film resistor, the thin film resistor only needs to generate 50 mW of heat in order to undergo thermal expansion deformation of 10 nm. In that case, the temperature rise of 10 ° C. or more is only in the vicinity of the thin film resistor, and the temperature rise is limited at a position 0.1 mm away. That is, if the heating device 4 is separated from the reproducing element 3 by 0.1 mm or more, the influence on the life of the reproducing element is very limited, and a highly reliable magnetic head slider can be provided. Strictly speaking, the relationship between the amount of thermal expansion deformation and the amount of change in flying height is not 1: 1, but it can be made closer to 1: 1 by devising the floating surface design described later.
[0019]
Next, the principle of adjusting the flying height will be described with reference to FIG. 5, taking as an example the case of compensating for the flying height fluctuation caused by the atmospheric pressure difference in the usage environment. FIG. 5A schematically shows the positional relationship between the disk 10 and the recording / reproducing elements 2 and 3 under the lowland condition. Let H0 be the flying height of the element under low-land conditions.
[0020]
FIG. 5B shows the positional relationship under high altitude conditions. When the atmospheric pressure is low at a high altitude, the air pressure generated on the floating surface such as the element installation surface 5a becomes smaller when compared with the same flying height, and the flying height becomes smaller when compared with the same load. That is, the element flying height H1 is smaller than H0, and the difference is an amount that cannot be ignored compared to the current design flying height. If the design is such that there is no marginal contact at low altitudes, contact between the disk and slider occurs at high altitudes, causing read / write errors due to slider vibration, read errors due to thermal asperity, and element damage due to wear. Conversely, if the design is such that it does not contact even at high altitudes, it must be used with a high flying height at low altitudes, and the recording density cannot be increased.
[0021]
FIG. 5C shows a state in which the heating devices 4a and 4b are energized and the super-shallow groove surfaces 6a and 6b are thermally expanded and deformed by the magnetic head slider structure of the present invention under high altitude conditions. By increasing the air pressure generated in the ultra-shallow groove surfaces 6a and 6b, it is possible to compensate for the lowering of the atmospheric pressure at high altitude, and to make the element flying height H2 equal to the original element flying height H0.
[0022]
Although the method for compensating for the flying height variation caused by the pressure difference has been described above, the case where the flying height variation caused by the temperature difference is compensated, the case where the element protrusion due to the heat generation of the recording element is canceled, and the individual head are also described. The same applies when adjusting the flying height fluctuation due to the difference.
[0023]
A conventional flying height adjustment method is a method in which a heating device is placed in the vicinity of the recording / reproducing element, and only the vicinity of the recording / reproducing element is projected to lower the flying height by energization. In the case of this method, it is designed not to contact at high altitude, and the flying height is reduced by energizing and projecting by the amount of increase in the flying height at low altitude. Considering the place where the magnetic disk device is used, since the frequency of the lowland is higher than the highland, the time for energization or the time required for large input power becomes long, and the power consumption is large. On the other hand, the flying height adjustment method of the present invention is a method of increasing the flying height by energization by increasing the flying surface area by bringing the flying surface near the heating device closer to the disk. In the case of this method, it is designed not to contact in the lowland, and the flying height is increased by energizing as the flying height decreases in the highland. Since the frequency of use at high altitudes is small (in terms of individual devices, although the frequency of use at high altitudes is higher for all devices), it requires less power consumption.
[0024]
Next, a method for detecting the flying height will be described. There is also a method of separately providing sensors for measuring atmospheric pressure and temperature, but in the state where all influences such as atmospheric pressure, temperature, individual differences are included, contact does not occur (too close) and an error occurs in reproduction of magnetic information ( If the two conditions are satisfied, it is best to monitor the contact and regeneration errors and perform feedback control to adjust the input power to the heating device only when they occur. It is a simple control method. In order to prevent the element from being damaged by the impact due to the load, it is effective to increase the flying height by energizing the heating device when the slider is loaded on the disk, especially when the apparatus is activated.
[0025]
FIG. 9 shows a control algorithm from when the apparatus is activated. A contact detection method will be described later. As shown in the figure, the method of compensating for the flying height fluctuation caused by the atmospheric pressure difference and the flying height fluctuation caused by the individual head difference is only required at the time of start-up. It is necessary to monitor contact and regeneration errors at all times during use.
[0026]
The method for detecting contact includes (1) a method using an acoustic emission (AE) sensor, (2) a method for monitoring thermal asperity, which is noise that appears in a reproduction signal due to contact heat generation, and (3) a slider pivoting by contact frictional force. For example, there is a method of monitoring an off-track signal in which a slight rotation occurs and off-track occurs.
[0027]
On the other hand, what is necessary is just to monitor what is called a bit error rate about the reproduction | regeneration error of magnetic information. Unlike playback errors, recording errors are difficult to monitor, but during recording, the element part expands due to coil heat generation of the recording element and the flying height is generally lower than during playback, so playback errors do not occur If the condition is met, the possibility of a recording error is low.
[0028]
In addition, as another method for adjusting the flying height, there is a method of in-situ observation of the distance between the reproducing element and the medium using the amplitude of the reproducing signal, which can be applied.
[0029]
The advantage that the positions of the heating devices 4a and 4b (or the positions projected onto the air bearing surface) are not the element installation surface 5a but the ultra-shallow groove surfaces 6a and 6b is that when the heating device 4 is not heated, some rolls Even if there is an attitude, it is possible to guarantee that the portion of the air bearing surface that is very close to the recording / reproducing element is the lowest point (the point that is closest to the disk). In other words, there is little difference between the flying height at the minimum flying height position and the flying height at the recording / reproducing element position, and the flying height loss is small. Conversely, when the width of the edge on the outflow end side of the element installation surface is wide, the distance between the minimum flying height position and the recording / reproducing element position is large, and the flying height loss increases.
[0030]
It is known that when the width of the edge on the outflow end side of the element installation surface is narrowed to about 30 μm to 60 μm, the access performance to the disk is improved, and the structure of this embodiment is from the point of improving the access performance to the disk. Is also advantageous.
[0031]
When the heights of the super shallow groove surfaces 6a and 6b in FIGS. 2 to 5 are the same as those of the element installation surface 5a, the flying height loss is larger as compared with the present embodiment as described above, and the disk The effect of the present invention can be obtained in the same manner, although the approaching performance to is not improved. That is, since the position of the reproducing element 3 and the heating device 4 is 0.1 mm or more, the influence on the life of the reproducing element is small, and the adjustment is made in the direction in which the flying height is increased by energization, and thus the required power consumption is small.
[0032]
Strictly speaking, the relationship between the amount of thermal expansion deformation and the amount of change in flying height is not 1: 1, but if the width of the outflow end side of the element installation surface is made as small as possible, while the width of the ultra-shallow groove surface is made as large as possible. good. In other words, if the ratio of the load on the element installation surface to the load on the ultra-shallow groove surface is adjusted and the ratio of the load on the element installation surface is made as small as possible, the relationship between the thermal expansion deformation amount and the flying height change amount is 1 Can be close to one-on-one. FIG. 6 shows an example in which the ratio of the load on the element installation surface 5a is made as small as possible as the second embodiment of the present invention. As a result of analyzing the pressure change generated by using the area of the element installation surface as a parameter, the area of the element installation surface 5a is preferably 0.005 square mm or less.
[0033]
FIG. 7 is an enlarged view of the vicinity of the outflow end of the slider perspective view showing the third embodiment of the present invention. The same numbers as those shown in the first embodiment are the same. The difference between the present embodiment and the first and second embodiments is that the ultra-shallow groove surfaces 6a and 6b provided with the heating devices 4a and 4b are separated from the element installation surface 5a and separated by the shallow groove surface 7a. Is a point. In this way, the distance D from the heating devices 4a, 4b to the reproducing element 3 becomes larger than in the first and second embodiments, and the risk that the reproducing element is heated and affects the life is further reduced. Further, the deformation due to the thermal expansion is limited to the super-shallow groove surfaces 6a and 6b, and the element installation surface 5a separated by the shallow groove surface hardly moves. Therefore, the above-described thermal expansion deformation amount and flying height change amount The relationship approaches one to one. The area of the element installation surface 5a is as small as possible and is preferably 0.005 square mm or less.
[0034]
In the case where the heights of the super shallow groove surfaces 6a and 6b in FIG. 7 are the same as those of the element installation surface 5a, the flying height loss is larger than that of the present embodiment, and the performance of accessing the disk is not improved. However, the effects of the present invention can be obtained similarly.
[0035]
FIG. 8 is an enlarged view of the vicinity of the outflow end of the slider perspective view showing the fourth embodiment of the present invention. The same numbers as those shown in the first embodiment are the same. The difference between the present embodiment and the first to third embodiments is that the ultra-shallow groove surfaces 6a and 6b provided with the heating devices 4a and 4b are separated from the element installation surface 5a and separated by the deep groove surface 8. It is. In this way, the distance D from the heating devices 4a, 4b to the reproducing element 3 is further increased as compared with the first to third embodiments, and the risk that the reproducing element is heated and affects the life is further reduced. . Further, the deformation due to thermal expansion is limited only to the super-shallow groove surfaces 6a and 6b, and the element installation surface 5a separated by the shallow groove surface hardly moves. The relationship approaches one to one. The area of the element installation surface 5a is as small as possible and is preferably 0.005 square mm or less.
[0036]
In FIG. 8, when the height of the super shallow groove surfaces 6a and 6b is the same as that of the element installation surface 5a, the flying height loss is larger than that of the present embodiment, and the access performance to the disk is not improved. However, the effects of the present invention can be obtained similarly.
[0037]
【The invention's effect】
In the present invention, firstly, the thin film resistor, which is a heating device, is sufficiently separated from the recording / reproducing element, and secondly, the air pressure generated on the air bearing surface increases due to the protrusion of the air bearing surface partly due to energization of the resistor. By designing the air bearing surface as described above, it is possible to realize a flying height adjustment that requires less power consumption without affecting the life of the reproducing element. As a result, the flying height margin can be eliminated by adjusting the flying height for each individual head or according to the usage environment, and the flying height of the recording / reproducing element is greatly reduced while preventing contact between the slider and the disk. This contributes to an increase in recording density on the magnetic disk surface, and further to an increase in capacity or size of the apparatus.
[Brief description of the drawings]
FIG. 1 shows a magnetic disk drive equipped with a magnetic head slider of the present invention.
FIG. 2 is a slider according to a first embodiment of the present invention.
FIG. 3 is an enlarged view of the vicinity of the slider outflow end of the first embodiment.
FIG. 4 is a diagram of the slider of the first embodiment viewed from the outflow end side.
FIG. 5 is an explanatory diagram of a flying height adjustment mechanism according to the first embodiment.
FIG. 6 is an enlarged view of the vicinity of the slider outflow end of the second embodiment.
FIG. 7 is an enlarged view of the vicinity of the slider outflow end of the third embodiment.
FIG. 8 is an enlarged view of the vicinity of a slider outflow end according to a fourth embodiment.
FIG. 9 is a flowchart showing a magnetic head slider control method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Magnetic head slider, 1a ... Slider board | substrate part, 1b ... Slider thin film head part, 2 ... Recording element, 3 ... Reproducing element, 4 ... Heating device, 5 ... Element installation surface, 5a, 5b, 5c ... Element installation surface structure Element 6 ... Ultra-shallow groove surface, 6a, 6b, 6c, Ultra-shallow groove surface component, 7 ... Shallow groove surface, 7a, 7b ... Shallow groove surface component, 8 ... Deep groove surface, 9 ... Air bearing surface, 10 DESCRIPTION OF SYMBOLS ... Magnetic disk, 11 ... Magnetic disk apparatus, 12 ... Air inflow end surface, 13 ... Air outflow end surface, 14 ... Lamp, D ... Distance between reproduction | regeneration element and heating apparatus, D1 ... Depth from element installation surface of ultra shallow groove surface D2: Depth of shallow groove surface from element installation surface, D3: Depth of deep groove surface from element installation surface, H0: Element flying height in low altitude, H1: Element flying height when not heating in high altitude, H2 ... Floating height when heated at high altitude

Claims (5)

An air bearing surface facing the magnetic disk rotates, the reproducing device for reproducing information from the recording element and the magnetic disk for recording information on the magnetic disk, the thermal expansion of the distance between these elements the magnetic disk surface in the magnetic head slider and a tO aDJUST pressurized thermal device,
The air bearing surface, the recording element and the first surface reproducing device is installed, a second surface and a predetermined depth from the second surface having a predetermined depth from the first surface A third surface having
The projection position of the heating device to the air bearing surface, the write element and the installation portion said second surface or magnetic head slider that has been separated by said third face. A substrate portion, the magnetic head slider and a head portion having a recording element and a reproducing element and heating equipment formed in the substrate portion on,
The head portion includes a first surface on which the recording element and the reproducing element are installed, and a second surface having a predetermined depth from the first surface ,
Wherein a heating device is projected to the air bearing surface of the head portion position, magnetic head slider only on the second plane. Wherein a portion of the second surface, the depth from the first surface is a magnetic head slider according to 請 Motomeko 1 or 2 that shrink by the action of the heating device. The magnetic head slider according to any preceding one of crisis recording element and a reproducing element the installed area of the pad is Ru der 0.005 square mm 請 Motomeko 1 to 3.   A magnetic disk drive comprising the magnetic head slider according to claim 1.

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