CN101611444A - Disk substrate, disk and disk set - Google Patents

Abstract

Even purpose provides the disk high speed rotating, also can suppress to knock down, the reliability height, be suitable for the hard disk that stops that unloading manner starts disk with substrate and the disk that uses this substrate.Disk of the present invention is the glass substrate (10) of circular plate type with the representational structure of substrate, have general planar first type surface (11), end face (12), be formed on fillet surface (13) between first type surface (11) and the end face (12) and the circumferential edges place in first type surface (11) the portion that deviates from respect to protuberance of the tabular surface beyond this circumferential edges or sedimentation, the size that deviates from portion is in the whole circumference of glass substrate (10) about equally.

Description

Disk substrate, disk and disk set

Technical field

The present invention relates to be used for disk substrate, disk and the disk set of magnetic recording media.

Background technology

In recent years, along with the high development of informationization technology, information recording technique, especially Magnetographic Technology have obvious improvement.Disk is as the magnetic recording media that is loaded on the HDD (hard disk drive) as one of magnetic recording media etc.Disk is to cover NiP films such as (nickel phosphorus) on the metal substrate of almag system, or lamination basalis, magnetosphere, protective seam, lubricating layer ground constitute successively on substrates such as glass substrate, ceramic substrate.At present, be extensive use of aluminium base as the disk substrate.But, along with miniaturization, thin plateization and the high density recordingization of disk, gradually to compare the glass substrate conversion that the flatness of substrate surface and substrate intensity are all high with aluminium base.

And, in order on portable equipment or automobile, to load jumbo magnetic recording media, require to improve impact resistance, in this, the glass substrate that rigidity is high also has superiority.In order to be loaded on the portable equipment, the size of substrate has the trend of dwindling.Therefore, require 2.5 inches, 1.8 inches, 1 inch even littler substrate gradually from 3.5 inches present substrates.Substrate is more little, and the scale error that is allowed is also little, requires more accurate shape processing.

And along with the densification of magnetic recording media, magnetic head also develops to magnetoresistive head (MR magnetic head), large-scale magnetoresistive head (GMR magnetic head) from thin-film head, and magnetic head narrows to below the 10mm from the floatation volume of substrate.But have following problem, that is, make magnetic head under disk has floated the situation of flying with extremely narrow floatation volume like this, be easy to generate flight friction obstacle (Off ラ イ ス テ イ Network シ ヨ Application).Flight friction obstacle is meant at the float magnetic head of flight of disk and makes and float posture and floatation volume changes, produces irregular regeneration thereupon and export variation.And,, then float the head crash obstacle that aloft magnetic head contacts with disk sometimes if produce this flight friction obstacle.Therefore, require glass baseplate surface to have the flatness and the smoothness of height.

And,, do not use existing C SS mode (contact start stop (CSS)), and use loading and unloading (Load Unload) mode instead in order to effectively utilize the area of glass baseplate surface.The CSS mode is the mode that magnetic head is contacted with substrate surface, need CSS be set at substrate surface and use zone (with the sliding area that contacts of magnetic head).And handling mode is to make magnetic head keep out of the way the mode in the glass substrate outside when disk stops, and has CSS and also can be used as the advantage that record surface uses with the zone.And, when disk set stops,,, therefore, the damage of disk can be suppressed at Min. because magnetic head is kept out of the way even be subjected to strong impact.In mini-hard disk movably,, select the startup regeneration of handling mode and utilize the combination of the disk of glass substrate from guaranteeing the angle of information recording capacity, resistance to impact.

In handling mode, owing to the end of magnetic head by glass substrate, therefore, especially the shape of the outer edge part of glass substrate becomes problem.If in the outer edge part shape disorder of glass substrate (protuberance or sedimentation), then upset the posture of floating of magnetic head, magnetic head comes in contact when the outside of glass substrate enters or when going out easily, thereby produces the possibility of knocking down.Therefore, especially require the disk outer edge part to have high flatness.

And disk is not only densification, also needs high speed.At present, loaded the rotational speed of the disk set of glass substrate with relative low speed such as 4200rpm.But use for example above rotating speed of 7200rpm in recent years.And, might use the above rotating speed of 10000rpm in the near future.If carry out such high speed rotating, especially near the linear velocity the disk outward flange increases.For example, be on the disk of 4200rpm at rotating speed, be 14.3m/ second apart from the linear velocity of the radius 32.5mm position of substrate center, under 5400rpm, linear velocity is 18.4m/ second, under 7200rpm, linear velocity is 24.5m/ second.Like this, especially, the outer edge part of the disk that on-line velocity is high is easy to generate above-mentioned flight friction obstacle and head crash obstacle.Therefore, in this, especially require outer edge part that high flat degree is arranged.

And, also restudying contact slidingtype recording medium (contact history formula recording medium) in recent years.Contact slidingtype recording medium is to make record-header contact the recording mode of reading and writing under the state that slides with disk.The recording mode that contact slidingtype recording medium just has before itself being because record-header is narrow more with the interval of disk, can improve recording density more, and therefore, consideration is again as the recording mode of Future Development.And if reduce the floatation volume of record-header, record-header contacts with disk sometimes.That is, the result who has reduced the floatation volume of record-header is that record-header partly contacts slip sometimes with disk.But, under the situation that contact is slided, have the big problem of wearing and tearing of record-header.And, have following problem, that is, if record-header is beated, then signal quality descends, or owing to the collision that separates contact makes record-header to damage.Mostly these are that the fast more influence of the rotational speed of disk (being linear velocity) is big more because magnetic disk surface concavo-convex causes.Therefore, in this also the special requirement outer edge part high flat degree is arranged.

On the other hand, shown in previous patent document 1 (TOHKEMY 2005-141852), when grinding board main, has the not enough problem of flatness of outer edge part.That is, glass substrate uses grinding pad to push with clamping positive and negative first type surface, and one side is supplied with the slurry relatively mobile glass substrate of one side and the grinding pad that contain abrasive material and ground.At this moment, produce in the outer edge part of first type surface and be called the sliding protuberance that jumps (other parts of the peripheral portion proportion by subtraction first type surface of first type surface are outstanding) or produce the sedimentation that is called decline (outer edge part of first type surface forms than other parts of first type surface and relatively the state that reams to more).Sliding jump and descend produce a kind ofly sometimes, also produce simultaneously sometimes.

Patent documentation 1: TOHKEMY 2005-141852 communique

Summary of the invention

As mentioned above, just because of the outer edge part linear velocity maximum of disk, therefore concavo-convex influence is also big, is that flatness requires the highest position.And, for the flatness of outer edge part of passing through also to require disk of the magnetic head in the handling mode.But, producing in this outer edge part and slidingly to jump or descend, flatness reduces easily.Therefore, need manage to reduce as far as possible and slidingly jump and descend, maybe the sliding glass substrate that jumps and descend after reducing is used for disk.And, when making disk with substrate also with this end shape as one of standard of judging certified products/unacceptable product.

But using the disk carried out above-mentioned management is the problem with head crash pilosity with substrate, the result that produces disk, manufacturing hard disk.

Therefore, try to reduce head crash by the management value that makes the above-mentioned end shape of regulation stricter (making based on the criterion of the certified products/unacceptable product of end shape stricter).Its result, the ratio that head crash takes place reduces relatively, but the problem that produces head crash is arranged.

The present invention forms in view of the above problems, the disk high speed rotating is provided, also can suppresses to produce and knocks down, the reliability height, is suitable for utilizing handling mode to start the substrate of the hard disk that stops and the disk that uses this substrate even its objective is.

Present inventors have carried out deep research with regard to the problems referred to above, consequently, even be conceived to make above-mentioned management value stricter, the situation of head crash take place also sometimes, have observed the end shape of each substrate.So finding the interior end shape of face of the glass substrate that judgement management value is no problem exists uneven.

First mode of the present invention

And, present inventors find by suppressing the inequality of the end shape in the glass substrate face, more specifically be to make protuberance (sedimentation) shape on the first type surface end of glass substrate roughly the same with the short transverse of the first type surface quadrature of this glass substrate, the glass substrate that can prevent head crash can be provided, thereby finish first mode of the present invention.

Promptly, the disk of first mode of the present invention is the substrate of circular plate type with the representational formation of substrate, have general planar first type surface, end face, be formed on fillet surface between first type surface and the end face and the circumferential edges place in first type surface the portion that deviates from respect to protuberance of the tabular surface beyond this circumferential edges or sedimentation, that deviates from portion deviates from size in the whole circumference of substrate about equally.

In other words, it is characterized in that, the first type surface of substrate and chamfered section between have the portion that deviates from respect to this first type surface protuberance or sedimentation, under the situation of the first type surface of overlooking substrate, the portion that deviates from surrounds first type surface with roughly the same height.At this, " roughly the same height " for example is to deviate from the difference in height of portion preferably in 5nm.

According to above-mentioned formation, can improve the flatness of disk with the especially outer edge part of substrate.Therefore, especially on the outer edge part of disk, can not upset the posture of floating of disk, even under the situation that makes the disk high speed rotating, disk and the danger that magnetic head does not also contact can improve reliability.And,, do not have the danger that posture is especially upset or contacted with disk by the outer edge part of disk of floating of magnetic head for passing through of the magnetic head in the handling mode yet.

Promptly, roughly the same by making the first type surface end that is formed on substrate and being formed on the height of the shape for lugs (protuberance) on the substrate whole circumference at the circumferencial direction of substrate, make disk set (hard disk drive: under situation HDD) at this substrate of use, can make the flight stability that floats of magnetic head, therefore can prevent to cause head crash.

The size that deviates from is preferably roughly the same at the circumferencial direction of radial location arbitrarily.Because magnetic head mainly in circumferencial direction scanning, therefore, by roughly the same at circumferencial direction, can further prevent contacting of disk and magnetic head on disk.

On substrate, the portion that will deviate from circumferencial direction under 30 ° of situations of measuring 12 points, deviate from the variation of size, promptly poor (variable quantity) of the direction of and first type surface quadrature substrate in the portion along deviating from of forming of the circumference of substrate be preferably below the 5nm.By in such scope, can more positively obtain the effect of first mode of the present invention.

Deviate from protuberance in the portion or sedimentation and be maximum (Very portion of limit portion) the roughly the same distance in center of preferred distance substrate.In other words, this substrate has circular hole at the center, and on above-mentioned first type surface, to deviate from protuberance in the portion or sedimentation be that the center of the circle that forms of maximum limit portion is preferably placed at the position roughly the same with the center of above-mentioned circular hole by above-mentioned.Like this, can make circumferencial direction deviate from big or small roughly the same.

On first type surface, be that the circularity of the circle that forms of maximum extremely preferred portion is preferably in 600 μ m by deviating from protuberance in the portion or sedimentation.More preferably in 400 μ m.Better is in 200 μ m.If circularity reduces (value increases), though then limit portion deviate from big or small identical, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making circularity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

Substrate has circular hole at the center, at first type surface, is that the concentricity of the circle that forms of maximum limit portion and circular hole is preferably in 1200 μ m by deviating from protuberance in the portion or sedimentation.More preferably in 1000 μ m.Better is in 800 μ m.If concentricity reduces (value increases), though then limit portion deviate from identically, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making circularity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

And, from seeing above-mentionedly when deviating from portion, consider the size of record-header with respect to the disk radial direction with the direction of above-mentioned first type surface quadrature, connect the preferred 0.02mm+1.00mm of circularity (width of the micromicron sled of the record-header)=1.02mm of this circle that deviates from portion.In other words, when the section of glass substrate is seen, exist the above-mentioned variation that deviates from the position of portion on the radial direction of substrate, preferably to be controlled at 1.02mm with interior scope.

Substrate also can be carry magnetic head pack into through the outward flange of disk, with respect to the first type surface of disk and the disk set of the handling mode that unloads on the disk substrate.Because the flatness height of outer edge part can form the substrate that is suitable for handling mode.

Substrate also can be to be used to carry make disk with the disk substrate on the disk set of the rotating speed rotation of 5400rpm at least.Because the flatness height of outer edge part, even therefore under the situation of high speed rotating, the danger that does not also have disk to contact with magnetic head can improve reliability.

The feature of the representational formation of the manufacture method of the disk of first mode of the present invention is to form magnetosphere at the disk that obtains with the manufacture method of substrate by above-mentioned disk at least on the surface of substrate.Like this, the outer edge part that can make first type surface also has the disk of height flatness.

Second mode of the present invention

And, present inventors find by suppressing the inequality of the end shape in the glass substrate face, more specifically be to make the shape for lugs on the first type surface end of glass substrate roughly the same on the radial direction of this glass substrate, the glass substrate that can prevent head crash can be provided, thereby finish second mode of the present invention.

Promptly, in order to address the above problem, the disk of second mode of the present invention is the substrate of circular plate type with the representational formation of substrate, have general planar first type surface, end face, be formed on fillet surface between above-mentioned first type surface and the end face and the circumferential edges place in above-mentioned first type surface form protuberance with respect to the tabular surface beyond this circumferential edges the portion that deviates from, the above-mentioned whole circumference formation that deviates from portion along this substrate, the above-mentioned protuberance that deviates from portion is the maximum limit portion distance roughly the same apart from the center of this substrate.

According to above-mentioned formation,, can improve flatness as the circumferencial direction of record-header direction of scanning in the especially outer edge part of disk with substrate.Therefore, especially on the outer edge part of disk, can not upset the posture of floating of disk, even under the situation that makes the disk high speed rotating, disk and the danger that magnetic head does not also contact can improve reliability.And,, do not have the danger that posture is especially upset or contacted with disk in the outer edge part of disk of floating of magnetic head for passing through of the magnetic head in the handling mode yet.

Promptly, roughly the same by making the first type surface end that is formed on substrate and being formed on the position of radial direction of the shape for lugs (protuberance) on the substrate whole circumference at the circumferencial direction of substrate, make disk set (hard disk drive: under situation HDD) at this substrate of use, can make the flight stability that floats of magnetic head, therefore, can prevent head crash.

At first type surface, the limit portion that deviates from the portion of preferred protuberance deviates from the whole circumference of portion at this, from the center of this substrate to the distance of the radial direction of external diameter, be in 92.0～97.0% scope.And peripheral end face that also can substrate is a benchmark, in the scope of end face 1～2.6mm.Like this, can be by measuring the position of the limit such as sliding jump, descend or prune (ダ Block オ Off) understanding portion.

On first type surface, the circularity of the circle that is formed by limit portion is preferably in 600 μ m.More preferably in 400 μ m.Better is in 200 μ m.If circularity reduces (value increases), though then limit portion deviate from big or small identical, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making circularity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

This substrate has circular hole at the center, and at first type surface, the circle that is formed by limit portion and the concentricity of circular hole are preferably in 1200 μ m.More preferably in 1000 μ m.Better is in 800 μ m.If concentricity reduces (value increases), though then limit portion deviate from big or small identical, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making concentricity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

The size that deviates from that deviates from the portion also can be roughly the same on the whole circumference of this substrate.That is, the first type surface of substrate and fillet surface between have the portion that deviates from respect to this first type surface protuberance or sedimentation, under the situation of the first type surface of overlooking substrate, the height that the portion of deviating from also can be roughly the same surrounds first type surface.The size that deviates from is preferably roughly the same at the circumferencial direction of radial location arbitrarily.Because magnetic head mainly scans on disk at circumferencial direction, therefore, by roughly the same at circumferencial direction, can prevent further that disk from contacting with magnetic head.At this, " roughly the same " is meant and considers the big or small both sides of circularity at above-mentioned scope and the relative disk radial direction of record-header, preferably 0.02mm+1.00mm (width of the micromicron sled of record-header)=1.02mm.

Deviating from portion, the variation of the size that deviates from, promptly poor (variable quantity) of the direction of and first type surface quadrature substrate in the portion along deviating from of forming of the circumference of substrate preferably below 5nm.By in such scope, can further obtain the effect of second mode of the present invention really.

This substrate also can be carry magnetic head pack into through the outward flange of disk, with respect to the first type surface of disk and the disk set of the handling mode that unloads on the disk substrate.Because the flatness height of outer edge part can form the substrate that is suitable for handling mode.

This substrate also can be to be used to carry make disk with the disk substrate on the disk set of the rotation of the rotating speed more than the 5400rpm at least.Because the flatness height of outer edge part, even therefore under the situation of high speed rotating, the danger that does not also have disk to contact with magnetic head can improve reliability.

The feature of the representational formation of the manufacture method of the disk of second mode of the present invention is to form magnetosphere at the disk that obtains with the manufacture method of substrate by above-mentioned disk at least on the surface of substrate.Like this, the outer edge part that can make first type surface also has the disk of height flatness.

According to first mode of the present invention, can improve the flatness of disk with substrate especially outer edge part.Therefore,, can not upset the posture of floating of magnetic head, even and under the situation that makes the disk high speed rotating, the danger that does not also have disk to contact with magnetic head can improve reliability especially in the outer edge part of disk.And,, do not have the danger that posture is especially upset or contacted with disk in the outer edge part of disk of floating of magnetic head for passing through of the magnetic head in the handling mode yet.

According to second mode of the present invention,, can improve flatness as the circumferencial direction of record-header direction of scanning in the especially outer edge part of disk with substrate.Therefore, especially on the outer edge part of disk, can not upset the posture of floating of disk, and even under the situation that makes the disk high speed rotating, disk and the danger that magnetic head does not also contact can improve reliability.And,, do not have the danger that posture is especially upset or contacted with disk in the outer edge part of disk of floating of magnetic head for passing through of the magnetic head in the handling mode yet.

Description of drawings

Fig. 1 (a) is used to feature of the present invention is described and the figure that uses, be to be the figure that the situation of the sliding shape that jumps describes with the end shape of substrate to disk, Fig. 1 (b) is used to feature of the present invention is described and the figure that uses, is to be the figure that the situation of decline shape describes to disk with the end shape of substrate.

Fig. 2 is used to feature of the present invention is described and the figure that uses, is with the end shape of substrate, the maximum apart from the straight line that connects any point-to-point transmission is deviated from the figure that value describes to disk.

Fig. 3 is used to first embodiment of the invention is described and the figure that uses, be expression to disk with the end shape of substrate, measure the figure as a result that deviates from value apart from the maximum of the straight line of any point-to-point transmission of connection.

Fig. 4 is used to first embodiment of the invention is described and the figure that uses, be illustrated under the situation that disk is the sliding shape that jumps with the end shape of substrate, the figure as a result of the radial location of measuring limit portion.

Fig. 5 is used to first embodiment of the invention is described and the figure that uses, be expression to disk with the end shape of substrate, measure the figure as a result that deviates from value apart from the maximum of the straight line of any point-to-point transmission of connection.

Fig. 6 is used to second embodiment of the invention is described and the figure that uses, be illustrated under the situation that disk is the sliding shape that jumps with the end shape of substrate, the figure as a result of the radial location of measuring limit portion.

Fig. 7 is used to second embodiment of the invention is described and the key diagram that uses, be expression to disk with the end shape of substrate, measure the figure as a result that deviates from value apart from the maximum of the straight line of any point-to-point transmission of connection.

Embodiment

Below with regard to disk of the present invention with substrate and use this disk to describe with the embodiment of the disk of substrate.In addition, the size shown in following examples, material and other concrete numerical value etc. only in order to understand the example of invention easily, under the situation of impunity statement earlier, do not limit the present invention.

At first see figures.1.and.2 and just be used to illustrate that feature of the present invention uses " deviating from portion " and " limit portion " etc. to describe.

Fig. 1 is explanation as disk with the jump side view of shape and decline shape of the cunning of an example of the end shape of substrate.

Above-mentioned disk forms circular plate shape with substrate 10, is formed centrally circular hole therein.And as shown in Figure 1, disk has first type surface 11 as the recording of information regeneration zone, and the end face 12 and the fillet surface between this first type surface and end face 13 of these first type surface 11 quadratures with substrate 10.In addition, make the boundary of end face 12 and fillet surface 13 fuzzy by end surface grinding operation described later sometimes, therefore, the present invention also comprises the situation that the fillet surface 13 of end face 12 and both sides thereof is formed a curved surface.

First type surface is owing to being the zone that is used for information is carried out record regenerating, and is therefore mobile for floating of record-header, in fact forms smooth face.But, when making above-mentioned glass substrate 10, for example form in the circumferential edges of above-mentioned first type surface that core on the first type surface with glass substrate is compared, the portion that deviates from 14 of relative this first type surface protuberance or sedimentation.This deviates from interior all end side and peripheral end side both sides that portion 14 is formed on the first type surface of glass substrate.

Shown in Fig. 1 (a), the shape of the outer edge part protuberance that the sliding shape that jumps is a first type surface 11, shown in Fig. 1 (b), the decline shape is the shape of the outer edge part sedimentation of glass substrate 10.

Fig. 2 utilizes apart from the maximum of the straight line that connects any point-to-point transmission to deviate from the example that value is measured.That is, the straight line of point-to-point transmission is a reference field to connect arbitrarily, and the size (maximum deviates from value) of the limit portion 15 of the maximum point by measuring the conduct protuberance seen from this reference field or sedimentation is estimated.

As shown in Figure 2, to deviate from value be to connect the straight line of any R1, R2 and the ultimate range of the positive dirction in its scope at 2 to the maximum of point-to-point transmission.And,, can measure the state of above-mentioned limit portion 15 by setting the position of R1, R2 at 2 in the mode of above-mentioned limit portion 15 sides to comprise as the limit portion 15 on the summit of the sliding shape that jumps and to make apart from the ultimate range that connects above-mentioned straight line at 2.

As the setting of above-mentioned any 2 R1, R2, specifically can carry out following setting, for example be of a size of under the situation of substrate of 2.5 inches (external diameter 65mm Ф) at external diameter, make apart from the distance at the center of glass substrate and be respectively 29.9mm (R1), 31.5mm (some R2).In other words, when will be from the center of substrate when the distance of substrate end-face is made as 100%, can will determine above-mentioned 2 points arbitrarily as 2 ground from the position of substrate center 92% and 97% position.And, have the deviate from portion (protrusion or subsidence part) 14 of disk with substrate at this point-to-point transmission.And in these 2 is that magnetic head floats mobile zone from substrate center place far away.

In addition, in following embodiment, as mentioned above, circumferential edges that will be in first type surface, " deviating from " of the protuberance that forms of the tabular surface beyond this circumferential edges or the sedimentation tabular surface that is generically and collectively referred to as corresponding main surfaces relatively.And, be called the portion of deviating from 14 with forming this part that deviates from.In addition, see figures.1.and.2 as can be seen, presenting the position that maximum deviates from is limit portion 15.

First embodiment

At first describe with regard to first embodiment of the present invention.

(disk substrate)

Even present inventors reduce sliding jump or the concavo-convex high speed rotating of the disk first type surface that causes of descending also can suppress to produce the disk of knocking down in order to provide, carried out deep research, it found that, even identical substrate, in the different position of circumferencial direction, the sliding situation that jumps or descend is also different, has finished first mode of the invention described above thus.

That is, at present, glass substrate judges by the shape of measuring the circumferential edges part whether glass substrate is certified products before dispatching from the factory.But because the glass substrate price is low and must a large amount of produce, and the substrate after checking can not be as the product that dispatches from the factory (failure test), therefore, from batch extract several samples out, only measure respectively with regard to a position.And,, the glass substrate that is judged as unacceptable product is arranged also more or less in coasting test even make under the situation of disk through the glass substrate that measurement is judged as certified products in use.

Therefore, inventors are through detailed inspection, recognize if at circumferencial direction at a plurality of position measurement end shapes, then because the position difference, the position of limit portion 15 is also different with size.Therefore, though passed through to check batch, in case form disk, be assembled on the disk set, can not bring into play needed performance sometimes.On the other hand, form disk if will be formed on the jump maximal value of (protuberance) of size, the cunning that in other words will be formed on the end of first type surface of limit portion 15 of circumferential edges of the first type surface of glass substrate at the roughly the same glass substrate of circumferencial direction, the disk set of packing into then can not cause head crash.

Therefore, in the present embodiment, be formed on the whole circumference of glass substrate 10, and that to make protuberance in the portion of deviating from 14 or sedimentation be the peaked size that deviates from is roughly the same on glass substrate 10 whole round having formed the portion that deviates from 14 that deviates from.In other words, the first type surface 11 of glass substrate 10 with fillet surface between have the portion that deviates from 14 of relative this first type surface protuberance or sedimentation, under the situation of the first type surface of vertical transparency substrate, deviate from portion 14 and surround first type surface with roughly the same height.Below describe at this point.

Below the disk that is used to the to make present embodiment manufacture method with substrate is described.

Though make disk substrate (specifically as described later) through various operations, but make as the disk of present embodiment situation with substrate (at the peripheral edge portion of first type surface, have the substrate of limit portion 15 that conduct deviates from the summit of portion's (protrusion or subsidence part) 14 apart from the roughly the same distance in the center of this glass substrate) under, grinding step (second grinding step) is very important especially at last.In addition, main grinding condition by above-mentioned last grinding step decides the subsidence part that forms above-mentioned protrusion or above-mentioned relatively tabular surface formation sedimentation at the peripheral edge portion of first type surface.In addition, in the following description, describe with regard to the condition that is used to form protrusion.

Along with the raising of storage density, the height of desired above-mentioned protrusion obviously reduces, and determines most of main cause of its shape, size to depend on the grinding condition of last grinding step.

And the great majority of the various grinding conditions in the last grinding step are influential to shape, the size of above-mentioned protrusion, and wherein especially processing speed (process velocity) and tonnage have influence.

Below, just use the lapping device of planet wheel mode, the last grinding step that the first type surface of glass substrate is ground to describe.Certainly, do not use the lapping device of planet wheel mode can carry out above-mentioned last grinding step yet.For example also can use the lapping device of chip that above-mentioned glass substrate is carried out last grinding step.

In the end in the grinding step, by two first type surfaces that simultaneously utilize grinding pad to push this glass substrate grinding pad and glass substrate are relatively moved and grind above-mentioned glass substrate.At this moment, the process redundancy of unit interval is processing speed, and the pressure of pushing glass substrate is tonnage.

And,, preferably make processing speed in the scope that 0.20 μ m/ branch～0.45 μ m/ divides, and make tonnage in the scope of 8.0Pa～10.5Pa in order to make the magnetic glass substrate of present embodiment.Because the influence of other grinding conditions is smaller, therefore do not limit, for example under the situation of 2.5 inches disks (Ф 65mm), the hardness that can make grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is 1.0 (μ m).Under the situation of grinding under the condition except above-mentioned condition, the danger of end shape variation or breaking glass panel is arranged.

And, in order to make the magnetic disc substrate of present embodiment, preferably, grinding step in the end, behind grinding substrate under the tonnage (formal tonnage) that with the attrition process is purpose, grind substrate with tonnage than this formal tonnage low (for example 1Pa is following).Especially preferably the only about half of time that is used in the milling time of grinding substrate under the formal tonnage grinds with this low tonnage.By reducing the inequality of the circumferencial direction of end shape like this.

And, in order to make the magnetic glass substrate of present embodiment, preferably the glass substrate that can carry out chemical enhanced processing is carried out chemical enhanced processing after, by board main is ground, can obtain glass substrate for disc.Under the situation of carrying out chemical enhanced processing (ion-exchange treatment), end shape can be more coarse than grinding the back sometimes.Therefore, under the situation of the inequality of the circumferencial direction that reduces end shape, after having carried out chemical enhanced processing, carry out milled processed and can high yield rate produce the glass substrate for disc of the inequality of the circumferencial direction that has reduced end shape.In addition, having carried out the glass substrate of first type surface milled processed after chemical enhanced processing, is the glass substrate that at least a portion surface of substrate surface has ion exchange layer, and the bed thickness of the ion exchange layer of end face is thicker than first type surface.

And the glass substrate that has carried out the first type surface milled processed after chemical enhanced processing is being preferred aspect the roughness that reduces first type surface.The surfaceness of the desired substrate of perpendicular magnetic recording especially, in recent years obviously descends compared with the existing.In order to satisfy this requirement, preferably after chemical enhanced processing, carried out the glass substrate of first type surface milled processed.

In addition, the disk of present embodiment utilizes surface roughness Ra that AFM (electron microscope) measures preferably below 0.15nm with substrate.

And, in order to make the magnetic glass substrate of present embodiment, to carry out under the finally ground situation at the lapping device that uses the planet wheel mode, the relation from rotating speed and the revolution speed in device of carrier is also extremely important.

In the planet wheel mode, many glass substrates are remained on the carrier.And this maintained glass substrate is with the following thereon crimping grinding pad of carrier.And, under this state, simultaneously revolve round the sun by the rotation of carrier one side, grind above-mentioned glass substrate.That is because the direction that relatively moves of glass substrate and grinding pad is arbitrarily, be average therefore, but it doesn't matter fully with the circumferencial direction of glass substrate.Therefore, jump etc. for the cunning of the outer edge part that is formed on glass substrate, the position of its radial direction, size take place uneven on the position of circumferencial direction.

Therefore, in order to reduce the inequality of this circumferencial direction, preferably the ratio from rotating speed and revolution speed of carrier is set in 0.125～8 scope.Under the situation of grinding with the condition that surpasses this scope, mostly the jump shape of (protrusion) of the cunning that is formed on the circumferential edges of glass substrate is mixed and disorderly at circumferencial direction.

And, when when seeing this glass substrate with the direction of the first type surface quadrature of above-mentioned glass substrate, in the above-mentioned size that deviates from (highly) under the situation of circumferencial direction inequality, when disk rotation, record-header (magnetic head) scanning, produce strong variation up and down, record-header to float flight unstable.If record-header can not be followed the variation of the above-mentioned size that deviates from, head crash then takes place.

Be specifically described, record-header is under the situation of floating flight on the disk at this point, even this record-header under the big situation of the size variation that deviates from, can be followed under its variation ratio little (mild) situation.But, taking place then to cause collision under the big situation that deviates from variation during the small flying distance.That is, the disk of present embodiment is particularly useful for the situation that magnetic head floats flight at a high speed with substrate.

On the other hand, as above-mentioned formation, by on the whole circumference of glass substrate, form the size that deviates from of the portion of deviating from 14 roughly the samely, even the generation cunning jumps or descends, when record-header scans, as long as always by above the top of limit portion 15, then thinking does not have to produce the difference of height of the degree of knocking down.That is, to be conceived to the height change of the substrate surface on the circumferencial direction be important in the present invention.

Therefore,,, can reduce roughness, the fluctuating of circumferencial direction, improve flatness in the especially outer edge part of disk with substrate according to the formation of present embodiment.Therefore,, can not upset the posture of floating of magnetic head although the generation cunning jumps or descends yet, even under the situation that makes the disk high speed rotating, the danger that does not also have disk to contact with magnetic head.Like this, can improve reliability when packing disk into disk set tremendously.And, for passing through of the magnetic head in the handling mode, there is not the danger that posture is especially upset or contacted with disk in the outer edge part of disk of floating of magnetic head yet, therefore, record-header can stably pass through the disk end, and is very suitable.

The size that deviates from is preferably roughly the same at the circumferencial direction of radial location arbitrarily.Magnetic head mainly in circumferencial direction scanning, therefore, by roughly the same at circumferencial direction, can further prevent contacting of disk and magnetic head on disk.

At this, " roughly the same at circumferencial direction " is to consider to make the size of circularity at above-mentioned scope, the relative disk radial direction of record-header, preferably 0.02mm+1.00mm (width of the micromicron sled of record-header)=1.02mm.

Specifically be, for example on glass substrate, will deviate from portion 14 at circumferencial direction under 30 ° of situations of measuring 12 points, the variation that deviates from portion's size can be below 5nm.By in such scope, can further obtain effect of the present invention really.

And the protuberance or the sedimentation that deviate from the portion 14 preferably are in apart from the position of the roughly the same distance in the center of glass substrate for maximum limit portion 15.Even this is because the size that deviates from is roughly the same on whole circumference, if different with the distance at center, then neither be roughly the same at circumferencial direction.

Specifically be on first type surface, to be that the circularity of the circle that forms of maximum limit portion 15 can be in 600 μ m by deviating from protuberance in the portion 14 or sedimentation.Preferably in 400 μ m.Better is in 200 μ m.If circularity reduces (value increases), though then limit portion 15 deviate from big or small identical, but see that at circumferencial direction the size that deviates from neither be roughly the same.In other words, when the section of seeing on the radial location (deviating from the position that portion 14 exists) of the center regulation of glass substrate, if make the glass substrate rotation, the size (for example height of protrusion) that then deviates from the limit portion 15 of portion 14 changes.That is, record-header floats under the situation of flight in the radial location of afore mentioned rules, if this record-header can not be followed the above-mentioned variation that deviates from the size of portion 14, then produces head crash.But,, then can make the big or small relative record head that deviates from big or small roughly the same of circumferencial direction by making circularity in above-mentioned scope.

Be formed on glass substrate the center circular hole be that the concentricity of the circle that forms of maximum limit portion 15 can be in 1200 μ m by deviating from protuberance in the portion 14 or sedimentation.Preferably in 1000 μ m.Better is in 800 μ m.If concentricity reduces (value increases), though then limit portion 15 deviate from big or small identical, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making concentricity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

And the disk of present embodiment preferably makes disk use with the glass substrate on the disk set of the rotation of the rotating speed more than the 5400rpm as being used to be loaded in substrate.It is no problem certainly to be loaded on the disk set with the rotation of the rotating speed more than the 5400rpm, especially under the situation of the disk set that makes the disk high speed rotating, compare with substrate with non-disk of the present invention, use the disk of present embodiment very obvious with the effect of substrate.

And the disk of present embodiment preferably uses as following glass substrate with substrate, and this glass substrate is used to be loaded in the disk set that magnetic head moves in the portion that deviates from 14 of the circumferential edges that is present in this glass substrate with the linear velocity of 20.0m/ more than second.

And it is the following disk of 3～4nm that the disk of present embodiment preferably is used to touch end height (TDH) with substrate.If it is low to touch end height, then, cause collision easily being formed under the big situation of the variation that deviates from the above-mentioned glass substrate.But, by using the disk substrate of present embodiment, can make the variation of the portion of deviating from 14 littler than existing, therefore,, also can suppress head crash even reduce the floatation volume of magnetic head (record-header).

And it is 200GBit/inch that the disk of present embodiment is preferred for recording density with substrate ²The disk of above high record density, more preferably being used for recording density is 250GBit/inch ²More than the better disk of high record density.Under the situation of such high record density, though need make the floatation volume of record-header littler,, can further reduce the floatation volume of record-header by using the disk substrate of present embodiment, therefore, can suppress collision.In addition, be used for recording density less than the glass substrate of above-mentioned disk or be used to make touch end height greater than the disk of above-mentioned disk with the also applicable certainly disk substrate of the present invention of substrate.

In addition, the disk of present embodiment has smooth first type surface, end face with substrate and is present in fillet surface between this first type surface and the end face, and the peripheral edge portion of first type surface exist to this peripheral edge portion beyond the protrusion of direction protuberance of tabular surface quadrature, and, this disk substrate is a circular plate type, under the situation of the first type surface of vertical transparency substrate, above-mentioned protrusion surrounds above-mentioned first type surface, and above-mentioned protrusion also can surround above-mentioned first type surface by roughly the same height.

And, under the situation of the first type surface of vertical transparency substrate, the maximum point that deviates from portion 14 also can be present in central part with this glass substrate be benchmark, with respect to the distance of the profile of this glass substrate in 92.0～97.0% scope.

And under the situation of the first type surface of overlooking above-mentioned glass substrate, the limit portion 15 of above-mentioned protrusion surrounds above-mentioned first type surface circularly, and the circularity of the circle that is formed by above-mentioned limit portion 15 is preferably in 600 μ m.

And, above-mentioned glass substrate has circular hole at central part, under the situation of the first type surface of overlooking above-mentioned glass substrate, the limit portion 15 of above-mentioned protrusion surrounds above-mentioned first type surface circularly, and the concentricity of circle that is formed by above-mentioned limit portion 15 and the circle that formed by the circular hole of above-mentioned central part is preferably in 1200 μ m.

And, it is the glass substrate of circular plate type, above-mentioned glass substrate has smooth first type surface, end face and is present in fillet surface between above-mentioned first type surface and the end face, under the situation of the first type surface of overlooking above-mentioned glass substrate, between above-mentioned first type surface and fillet surface, have subsidence part, can make the locational above-mentioned subsidence part of the center gauge set a distance that leaves above-mentioned glass substrate roughly the same apart from the degree of depth of first type surface with respect to above-mentioned first type surface sedimentation.

And the disk of present embodiment preferably carries out chemical enhanced at least to end face with substrate, strengthen more preferred to substrate front (whole surface).In other words, above-mentioned disk more preferably forms compressive stress layers on its surface with substrate.Especially being installed in high speed rotating (for example 10000rpm) makes above-mentioned disk with under the situation on the disk set of substrate rotation or be installed under the situation on the disk set that uses as mobile purposes, require glass substrate to have resistance to impact, therefore, preferably form compressive stress layers at glass baseplate surface.In addition, chemical enhanced being meant here by glass substrate is contacted with the chemical enhanced processing that contains chemical enhanced salt night, a part of ion and the ion footpath contained in the glass substrate are replaced greater than the ion in the chemical enhanced treating fluid of this ion, thereby carry out the processing of hardened glass substrate.

(disk)

Can be by forming the disk that magnetic film is made present embodiment on substrate at above-mentioned disk.Because formation magnetic film on above-mentioned disk is used substrate, therefore, the shape of the first type surface of this disk is subjected to the very big influence of this glass substrate.That is,, need the shape of the first type surface of the above-mentioned glass substrate of raising in order to improve the shape of the first type surface on the disk.Therefore, use substrate as the disk substrate, can make and improve the especially disk of the shape of peripheral edge portion of first type surface by using the described disk of present embodiment.In addition, the manufacture method of disk is well-known, in this description will be omitted.

And, the disk of present embodiment also can be loaded in that magnetic head is packed into respect to first type surface through its outward flange and the disk set of the handling mode that unloads on disk.Because therefore the flatness height of the outer edge part of glass substrate can form the disk that is suitable for handling mode.

And the magnetic disc substrate of present embodiment also can be to be used to be loaded in make disk at least with the disk on the disk set of the rotation of the rotating speed more than the 5400rpm.Also the speed of being suitable for is the disk set of the speed that 7200rpm is above, 10000rpm is above.This be because: because the flatness height of the outer edge part of glass substrate, even therefore under the situation of high speed rotating, the danger that does not also have disk to contact, reliability height with magnetic head.

And the disk of present embodiment also can be a contact slidingtype recording medium (contact history formula recording medium).Contact slidingtype recording medium is owing to be to read and write in that record-header contact with disk under the state that slides, and therefore, as mentioned above, uses the flatness of circumferencial direction of the especially outer edge part of substrate by the raising disk, can prevent that record-header from takeofing.Like this, can improve signal quality, prevent that record-header from damaging.

(disk set)

By loading above-mentioned disk, can form disk set (hard disk drive).And, loaded above-mentioned disk is particularly suitable for being undertaken by high speed rotating recording of information regeneration with the disk set of substrate situation.

In addition, though be that the center describes with above-mentioned disk with the peripheral end face of substrate, interior all end faces also are formed as described above the portion of deviating from 14.And, this deviate from the portion 14 protuberance for maximum limit portion 15 certainly preferably apart from the roughly the same distance in the center of this glass substrate.

(the manufacturing management method of glass substrate for disc)

In the above description, illustrated by a plurality of diverse location measurements on glass substrate and pruned or sliding jumping waits the integral body to glass substrate to deviate from the structure that state is estimated.But, present situation be measure prune or the sliding needed time such as jump long, position needs about five minutes.Therefore, as the above embodiments, if measure 12 points, a substrate needs one hour.Since must low price a large amount of glass substrates of producing in ground, therefore, preferred omit as far as possible needn't measurement.

Therefore, in fact when making glass substrate for disc, only the maximum value in deviating from being present in real estate (protuberance or sedimentation) is measured the above-mentioned inequality that deviates from the real estate under the situation below the setting, judges certified products/unacceptable product.More particularly, the measurement operation of the size that measurement can be deviated from is divided into measuring and deviates from (protuberance or sedimentation) for the position measurement operation of maximum position with measure the concrete value that deviates from size and measure operation.For the position measurement operation, for example can consider to utilize the low measuring method of resolution of ratio measurement operation to measure rapidly and on a large scale.In this position measurement operation, though resolution is low, the size that can precision measure to a certain degree deviates from.Therefore, obviously surpass in the size that deviates under the situation of scope of certified products, do not need this substrate is carried out concrete measurement.On the other hand, when the scope of the size that deviates from, measure operation as value and can as above-mentioned embodiment, measure 12 points in the error range of scope that combines certified products and position measurement operation.

For the position measurement operation, specifically, for example use OptiFlat (production of Phase ShiftTechnorogy company) to scan whole glass substrate as the low light interference type surface profile measuring instrument of resolution, can determine the position of the maximum that deviates from.Measure operation for value, for example can use MicroXam (producing) to measure the concrete size that deviates from as the high light interference type surface profile measuring instrument of resolution with company.

By above-mentioned formation, can get rid of obviously needn't measurement, can cut down the needed time of operation of checking.

And, in the position measurement operation, grasp glass substrate deviate from size for maximum position after, measure operation as value and can only just a bit, only measure this locational size that deviates from.

Then, in judging operation, compare, can judge whether glass substrate is certified products by size and the setting that measured maximum is deviated from.Use under the situation about pruning deviating from value, deviate from value and be ± below the 10nm, preferably ± below the 7nm, more preferably ± below the 5nm.In addition, the measurement range that deviates from value can be set under the distance that plays the end from the center of glass substrate is 100% situation, apart from the center 92.0～97.9% scope for.

Like this, by only measuring deviating from of maximum in the substrate, need not to measure in a plurality of positions.Therefore, can promptly judge, can shorten the time of checking operation.

In addition, substrate of the present invention utilizes glass (can use amorphous glass or glass ceramics (glass ceramics).As the material of plate glass, sillico aluminate glass, soda-lime glass, borosilicate glass etc. are illustrated.But owing to the invention relates to disk with the shape of substrate, therefore, to disk with the material of substrate without limits, for example the substrate that is formed by other materials such as aluminium also is fit to use the present invention.But as mentioned above, especially in portable equipment, preferably compare the flatness of substrate surface and the good glass substrate of substrate intensity with aluminium base.

Disk of the present invention also can be following formation with substrate, promptly, be first type surface, the end face with general planar, the disk substrate that is formed on the fillet surface between above-mentioned first type surface and the end face, the tabular surface protuberance beyond the circumferential edges of above-mentioned first type surface has this circumferential edges relatively or the portion that deviates from 14 of sedimentation, the above-mentioned portion 14 that deviates from forms continuously at the circumferencial direction of first type surface, and this maximum height (maximum deviates from value) that deviates from the direction of portion 14 and above-mentioned first type surface quadrature forms on the whole circumference of this substrate roughly the samely.

And the above-mentioned portion 14 that deviates from can be formed on the neighboring of first type surface that endoporus is formed on the discoidal disk at center, also can be formed on inner periphery, also can be formed on both sides.And, in the present invention, deviating under the situation that portion 14 is formed on inner periphery and neighboring both sides, at least one side's the portion that deviates from 14 is that above-mentioned shape gets final product, but preferably the fast neighboring of the linear velocity of record-header is above-mentioned shape.

And, make disk by the disk that uses present embodiment with substrate, can form and touch the uneven little disk of end height (TDH) at the radial direction of substrate.Like this, the inequality of the end shape by reducing substrate can improve near the characteristic of floating of the magnetic head most peripheral of disk.

And the disk of present embodiment preferably uses as the substrate of the disk of corresponding DFH (dynamically flying height) magnetic head with substrate.Use under the situation of DFH magnetic head, magnetic disk surface and magnetic head near the distance obviously reduction compared with the existing of portion.But the disk of present embodiment can make the height of fluctuating below 20 μ m with substrate, and then below 12 μ m.And the surfaceness that can make board main is below 0.15nm, and then below 0.12nm.Therefore, use above-mentioned disk with under the situation of substrate, can further reduce the collision of DFH magnetic head at disk.

(embodiment)

Below just be suitable for disk of the present invention and describe with the embodiment of the manufacture method of substrate and disk.This disk is made as the disk with 3.5 inches disks (Ф 89mm), 2.5 inches disks (Ф 65mm), 0.8 inch disk (Ф 21.6mm), 1.0 inches disks (Ф 27.4mm), 1.8 inches disks (Ф 48mm) isotactic setting shape with substrate and disk.

(1) the shape manufacturing procedure and first polishing process

, at first, (grinding) polished on the surface of plate glass be processed to form base glass material with in the manufacture method of substrate at the disk of present embodiment, cut off this base glass material and cut out the glass disk.Plate glass can use various plate glass.This plate glass is material with the melten glass for example, can utilize well-known manufacture methods such as die pressing or float glass process, glass tube down-drawing, multistage stretching method, fusion method to make.Wherein, if use die pressing, can make plate glass at an easy rate.The material of plate glass can be used amorphous glass, glass ceramics (glass ceramics).The material of plate glass can use sillico aluminate glass, soda-lime glass, borosilicate glass etc.Especially amorphous glass, can implement chemical enhanced, and, can offer the flatness and the good disk substrate of substrate intensity of first type surface, in this, preferably use sillico aluminate glass.

In the present embodiment, adopt the direct pressing mold that has upper die and lower die, intermediate die (trunk type), the sillico aluminate glass of fusion is shaped to plate-like, obtained the plate glass of amorphous.In addition, as sillico aluminate glass, adopt and contain with SiO ₂: 58～75 weight %, Al ₂O ₃: 5～23 weight %, Li ₂O:3～10 weight %, Na ₂O:4～13 weight % are the chemically reinforced glass of major component.

Then, two first type surfaces of this plate glass are polished processing, become the base glass material of plate-like.This polishing processing is with the polishing both surfaces device with planetary gears, carries out with the alumina series free abrasive.Specifically, make polished land, the grinding fluid that contains free abrasive is supplied on the first type surface of plate glass, they are relatively moved, polish processing from pushing the two sides of plate glass up and down.Through this polishing processing, the base glass material that obtains having planar major surface.

(2) cut out operation (coring, shaping processing, chamfering)

Then, base glass material is cut off, cut out discoid glass substrate from this base glass material with diamond tool.Then, use diamond drill machine cylindraceous again, the central part formation endoporus at this glass substrate becomes circular glass substrate (coring).Then, utilize all end faces and peripheral end face in the diamond wheel grinding, the chamfer machining of stipulating (processing, chamfering are shaped).

(3) second polishing processing

Then, with first polishing process similarly, two first type surfaces of the glass substrate that obtains are carried out the second polishing processing.By carrying out this second polishing processing, can remove promptly cut out the trickle concaveconvex shape that is formed on the first type surface in operation, the end surface grinding operation in preceding operation in advance, make follow-up grinding step to finish at short notice to first type surface.

(4) end surface grinding operation

Then, with the brush Ginding process, peripheral end face and interior all end faces of glass substrate carried out mirror ultrafinish.At this moment, grind abrasive particle and be to use the slurry (free abrasive) that contains the cerium oxide abrasive particle.

Then, water cleans the glass substrate of having finished the end surface grinding operation.Through this end surface grinding operation, the end face of glass substrate is processed to the mirror status that can prevent that sodium, potassium from separating out.

(5) first type surface grinding step

As the first type surface grinding step, implement first grinding step earlier.The fundamental purpose of this first grinding step is to remove scar, the distortion that remains in aforementioned polishing process on the first type surface.In this first grinding step, by two sides lapping device, adopt the hard resin lap with planetary gears, carry out the grinding of first type surface.Lapping compound adopts the cerium oxide abrasive particle.

The glass substrate of this first grinding step that is through with, be impregnated into successively in each rinse bath of neutral detergent, pure water, IPA (isopropyl alcohol), clean.

Then, as the first type surface grinding step, implement second grinding step.The purpose of this second grinding step is that first type surface is finish-machined to mirror-like.In this second grinding step, by two sides lapping device, adopt flexible foamed resin ground tool with planetary gears, carry out the mirror ultrafinish of first type surface.Lapping compound adopts the cerium oxide abrasive particle thinner than the cerium oxide abrasive particle that uses in first grinding step.

The glass substrate of this second grinding step that is through with, be impregnated into successively in each rinse bath of neutral detergent, pure water, IPA (isopropyl alcohol), clean.In addition, each rinse bath has been applied ultrasound wave.

(6) chemical enhanced operation

Then, the glass substrate to be through with above-mentioned polishing process and grinding step carries out chemical enhanced.Chemical enhanced is the chemical enhanced solution of preparing to have mixed potassium nitrate (60%) and sodium nitrate (40%), should be heated to 400 ℃ by chemical enhanced solution, and the glass substrate after will cleaning is preheating to 300 ℃, floods about three hours in chemical enhanced solution.When this floods, chemical enhanced for the whole surface of glass substrate is carried out, to keep the mode of a plurality of glass substrates at end face, carry out at the state that is accommodated on the retainer.

Like this, by carry out dip treating in chemical enhanced solution, the lithium ion on glass substrate top layer and sodion are replaced as sodion and the potassium ion in the chemical enhanced solution respectively, have strengthened glass substrate.The thickness that is formed on the compressive stress layers on glass substrate top layer is approximately 100 μ m to 200 μ m.

The glass substrate of the chemical enhanced processing that is through with is immersed in 20 ℃ the tank and cools off rapidly, kept about ten minutes.Then, the substrate that cools off rapidly being through with is immersed in to be heated in about 40 ℃ concentrated sulphuric acid and cleans.Then, the glass substrate that will carry out sulfuric acid cleaned is impregnated into successively in each rinse bath of pure water, IPA and cleans.

As mentioned above, by implement first polishing process, cut out operation, second polishing process, end surface grinding operation, first and second grinding steps and chemical enhanced operation, obtain the disk substrate of smooth and level and smooth high rigidity.

(7) check operation

Check the shape of resulting disk with the outer edge part of substrate.Check operation by measuring operation and judging that operation constitutes, in measuring operation, a plurality of positions measurement of the circumferencial direction of glass substrate is deviated from value and limit portion 15; In judging operation, based on measured a plurality ofly deviating from value and limit portion 15, judging whether glass substrate is certified products.

(8) disk manufacturing process

On the two sides of having passed through the glass substrate that above-mentioned operation obtains; by carry out the film forming of adhesion layer that the Cr alloy forms, soft ferromagnetic layer that the CoTaZr alloy forms, basalis that Ru forms, perpendicular magnetic recording layer that CoCrPt base alloy forms, protective seam that hydrocarbon forms, lubricating layer that PFPE forms successively on the surface of glass substrate, make perpendicular magnetic recording disk.More specifically be to utilize online spraying and splashing facility on glass substrate, to carry out adhesion layer, the soft ferromagnetic layer of CoTaZr/Ru/CoTaZr, the middle layer of Ru, the CoCrPt-SiO of CrTi successively ₂Particulate magnetosphere, the film forming of hydrocarbon diaphragm, then, carry out the film forming of PFPE lubricating layer by infusion process, obtain disk.

In addition, this formation is the vertical disk of an example (PMR: formation perpendicular magnetic recording), but also can be used as horizontal disk (LMR: horizontal magnetic recording) constitute magnetosphere etc.Like this, the outer edge part that can make first type surface also has the disk of height flatness.

(9) disk set manufacturing process

And,, make disk set by above-mentioned disk groups is installed in the device.In addition, the formation of disk set is well-known, therefore, specifies in this omission.

(first embodiment)

Grinding condition shown below is applicable to second grinding step of above-mentioned (5) first type surface grinding step, makes disk with substrate, disk, disk set.In addition, in first embodiment, make 2.5 inches disks (Ф 65mm).Concrete grinding condition is that the hardness of grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is that 1.0 (μ m), processing speed are that 0.30 (μ m/ branch), tonnage are 9 (Pa).More specifically be, the tonnage in the last grinding step become two-stage, carry out attrition process with the formal tonnage of 9 (Pa) at the appointed time after, carry out attrition process during at the appointed time half of tonnage with 1 (Pa).And long-pending (the formal tonnage * processing speed) of the formal tonnage of this moment and processing speed is 2.7.

(first comparative example)

Except the grinding condition in above-mentioned second grinding step being made as following condition, utilize above-mentioned manufacture method to make disk substrate, disk, the disk set of first comparative example.The concrete grinding condition of first comparative example is that the hardness of grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is that 1.0 (μ m), processing speed are that 0.60 (μ m/ branch), tonnage are 12.0 (Pa).The grinding step of this moment is, at formal tonnage is to carry out attrition process under the state of 12.0 (Pa), do not reduce tonnage ground afterwards and carries out attrition process.And long-pending (the formal tonnage * processing speed) of the formal tonnage of this moment and processing speed is 7.2.

(comparison of first embodiment and first comparative example)

Be present in the disk shown in first embodiment and first comparative example, made shape by method inspection shown below with the limit portion 15 of the first type surface circumferential edges of substrate.

(A) influence of end shape

At first, investigate with regard to the influence of the height of the limit portion 15 of circumferencial direction.Specifically be that for the variation of the height of the circumferencial direction of investigating above-mentioned two glass substrates, the maximum of having measured any point-to-point transmission of two substrates deviates from value.The measurement range (R1 of Fig. 2, R2) that maximum deviates from value has determined to see first type surface circumferential edges that is formed on glass substrate and the measurement range that changes in the different limit portion 15 of the height of circumferencial direction.At this, be respectively the point (R2) of 29.9mm (R1), 31.5mm apart from the distance of substrate center, measuring equipment uses light interference type surface profile measuring instrument ((MicroXam (production of Phase Shift Technology company)) object lens multiplying power: 2.5 times, intermediate lens multiplying power: use 0.62 times, measure wavelength 553.2nm, measured zone 3.58 * 3.88mm, resolution 752 * 480 pixels).And, make glass substrate 30 ° of the each rotations of circumferencial direction, the position of measuring above-mentioned summit is totally 12 points.

That is, the maximum measured of said method deviates from the size that deviates from the summit (limit portion 15) that value representation connects straight line and the above-mentioned protrusion of above-mentioned R1 and R2.And its result as shown in Figure 3.

As shown in Figure 3, first embodiment compares with first comparative example, and the variation of the height of the circumferencial direction of glass substrate is little.Specifically be, the change difference of first embodiment is 2.86nm, and the change difference of first comparative example is 16.10nm.

(B) the loading and unloading test relatively

As mentioned above, after having made disk at first embodiment and first comparative example respectively and having formed magnetospheric disk on substrate, make disk set, load and unload test.Specifically being, the floatation volume of record-header is set at 9～10nm, is to test under two kinds of situations of 5400rpm and 7200rpm at the rotating speed that makes disk.

As a result, under the situation of the disk of first embodiment and first comparative example, even, also do not bump with rotating speed 1,000,000 loading and unloading repeatedly of 5400rpm.The disk of first comparative example bumps in 2,000,000 loading and unloading tests.

Yet, be after 7200rpm loads and unloads test with speed setting, even 1,000,000 loading and unloading repeatedly of the disk of first embodiment also do not bump, and the disk of first comparative example are bumping 800,000 times the time repeatedly.

Recognize that according to this result as shown in the present, being present in the size that deviates from of limit portion (summit of protrusion) 15 of the portion that deviates from 14 of first type surface circumferential edges of glass substrate, to be formed on the whole circumference of this glass substrate be very important roughly the samely.

In addition, in the present embodiment, the limit portion 15 that deviates from portion 14 uses the ground, summit of protrusions to be illustrated, but the present invention also can be the concave point that deviates from the limit portion of portion 14 15 use subsidence part.That is, on the big or small whole circumference that roughly the samely be formed on this glass substrate that deviate from of sedimentation, can obtain effect same as described above for maximum limit portion 15.

(C) surface configuration is specific

Then.Disk is investigated with the shape (end shape) of the first type surface circumferential edges of substrate.The size that deviates from of the portion that deviates from 14 that investigation is present in the first type surface circumferential edges of glass substrate is subjected to roughly the same disk on the whole circumference of this glass substrate with the concentricity of the position of the limit portion (summit of protrusion) 15 of substrate (above-mentioned first embodiment) and the influence of circularity.And, prepared the concentricity of position of limit portion (summit of protrusion) 15 and the other disk substrate of the above-mentioned first embodiment difference of roundness ratio as second comparative example.Make the situation of tonnage in the last grinding step and processing speed and above-mentioned first embodiment differently make the disk substrate of this second comparative example.Specifically be that relatively to make tonnage be that 8.0 (Pa), processing speed are 0.45 to make the disk substrate of second comparative example (μ m/ branch) to glass substrate.And long-pending (the formal tonnage * processing speed) of the formal tonnage of this moment and processing speed is 3.6.

Use light interference type surface profile measuring instrument (OptiFlat (production of Phase ShiftTechnology company)) to measure.In addition, OptiFlat compares with above-mentioned MicroXam, though resolution is low, measured zone is extensive.

Its result, the end shape that can find out the glass substrate of first embodiment, second comparative example is the sliding shape that jumps.And, measure the distance at sliding jump in shape summit (limit portion 15) and glass substrate center from this measurement result.And, for the displacement of the circumferencial direction of investigating above-mentioned vertex position, make glass substrate 30 ° of the each rotations of circumferencial direction, the position of measuring above-mentioned summit is totally 12 points.The result of this moment as shown in Figure 4.In addition, Fig. 4 represents to measure the result of the radial location of sliding the limit portion (sliding jumping a little) 15 that jumps.

Its result as shown in Figure 4, from the center of glass substrate, the disk that is formed on first embodiment is positioned at roughly the same position (distance) with the limit portion 15 of the first type surface circumferential edges of substrate, specifically be, apart from the center of glass substrate, be the center with 30.6mm, be positioned at ± scope of 0.2mm.And under the situation of second comparative example, be the center with 30.6mm, be positioned at ± scope of 1.4mm.

In addition, the disk of first embodiment is 0.40 (mm) with the circularity of substrate, and concentricity is 1.07 (mm).And the disk of second comparative example is 2.60 (mm) with the circularity of substrate, and concentricity is 5.68 (mm).And the height of limit portion 15 (deviating from value) is roughly the same in the formation of first embodiment and second comparative example.

And, in first embodiment and second comparative example, carry out rotating speed and be the loading and unloading test under 10000 situations of changeing.In addition, this test is carried out under the state that disk has been installed.And the floatation volume of the record-header of this moment is 9～10nm.Its result under the situation of first embodiment, even also do not bump for 1,000,000 times repeatedly, and under the situation of second comparative example, is bumping after 600,000 loading and unloading repeatedly.In addition, in first embodiment, repeat 1,000,000 times under the situation of 5400rpm and 7200rpm all not bump even be at rotating speed.

And although disk is roughly the same with the value that deviates from value on the substrate in first embodiment and second comparative example, being formed in to produce when carrying out coasting test with high speed rotating of second comparative example knocked down.And the formation of first embodiment does not produce and knocks down.If this is that the cunning of (not little) jumps owing to take place greatly, because circularity or concentricity height (being worth little), the then variation of the substrate surface of circumferencial direction (roughness, fluctuating) is few.And, find out that from a large amount of test findings preferably in 600 μ m, concentricity is preferably in 1200 μ m for circularity.

According to this result, limit portion 15 in the position of the circumferencial direction of glass substrate at radial direction identical and short transverse with low uncertainty, to making the disk high speed rotating the most favourable.

(D) adjust test

Adjust test to obtaining disk from first embodiment and first comparative example.Specifically be the adjustment the point (R2) of distance from 29.9mm (R1) to 31.5mm at the center of the glass substrate of measurement distance 2.5 inches (external diameter 65mm Ф) on the zone.

Concrete measuring condition carries out according to the order of following (1)～(3).

(1) disk is installed on the electromagnetic conversion characteristics measuring machine (manufacturing of グ one シ Star Network テ Network ニ カ Le エ Application one プ ラ イ ズ company), on magnetic head (DFH (dynamically the flying height) magnetic head) disk of packing into, write MF mode (frequency of half of the high frequency that hard disk uses).

(2) read output signal is imported oscillograph.

(3) then, obtain the adjustment in each zone on the interior any radial location of above-mentioned scope.

As a result, compare the result of first embodiment and first comparative example, the adjusted value of first embodiment is good.

And, use to have inequality (height of protrusion is at the identical substrate of circumferencial direction), the different magnetic disc substrate of above-mentioned circularity/concentric circles that the maximum identical with first embodiment deviates from value, carry out adjustment test same as described above.Its result, circularity 1200 μ m with interior, concentricity is good with the adjusted value of interior substrate at 600 μ m.If depart from these values, then adjust variation as a result.In addition, first embodiment and first comparative example are made disk under the same conditions.

(second embodiment)

Fig. 5 is expression deviates from the result of value apart from the maximum that is connected the straight line of any point-to-point transmission to second embodiment and the 3rd comparative example, measurement figure.Second embodiment processes under the condition identical with above-mentioned first embodiment, and the 3rd comparative example is processed under the condition identical with above-mentioned first comparative example.In addition, in order to compare, Fig. 5 also represents first embodiment and first comparative example simultaneously.And, the same with result shown in Figure 3, make glass substrate 30 ° of the each rotations of circumferencial direction, the position on the summit (limit portion 15) of the sliding shape that jumps of measurement is totally 12 points.

As shown in Figure 5, though the maximum of second embodiment deviates from value integrally than the first embodiment height, the variation (maximum-minimum) of glass substrate height in a circumferential direction is littler than first embodiment.On the other hand, although the 3rd comparative example is littler than the variation of first comparative example, move up and down brokenly as can be seen from Figure.In a word, the difference in change of first embodiment, second embodiment is little, be respectively 2.68nm, 1.95nm, and the difference in change of first comparative example, the 3rd comparative example is big, is respectively 16.10nm, 12.50nm.

In addition, the above embodiments, comparative example are that end shape is the situation of the sliding shape that jumps (with respect to the shape of first type surface protuberance).Even under situation,, also can obtain the result identical with the foregoing description and comparative example if carry out identical test with respect to the decline shape of board main sedimentation shape.

More than, describe with regard to the first suitable embodiment of the present invention with reference to accompanying drawing, but the present invention is not limited to this embodiment certainly.If those skilled in the art, various modifications in the scope that then obviously can expect in claim, putting down in writing or correction example, these also belong to technical scope of the present invention certainly.

Second embodiment

Below describe with regard to second embodiment of the present invention.

(disk substrate)

Even present inventors reduce sliding jump or the concavo-convex high speed rotating of the disk first type surface that causes of descending also can suppress to produce the disk of knocking down in order to provide, carried out deep research, it found that, even identical substrate, in the different position of circumferencial direction, the sliding situation that jumps or descend is also different, has finished second mode of the invention described above thus.

That is, at present, glass substrate judges by the shape of measuring the circumferential edges part whether glass substrate is certified products before dispatching from the factory.But because the glass substrate price is low and must a large amount of produce, and the substrate after checking can not be as the product that dispatches from the factory (failure test), therefore, from batch extract several samples out, only measure respectively with regard to a position.And,, the glass substrate that is judged as unacceptable product is arranged also more or less in coasting test even make under the situation of disk through the glass substrate that measurement is judged as certified products in use.

Therefore, inventors are through detailed inspection, recognize if at circumferencial direction at a plurality of position measurement end shapes, then because the position difference, the position of limit portion 15 is also different with size.Therefore, though passed through to check batch, in case form disk, be assembled on the disk set, can not bring into play needed performance sometimes.On the other hand, form disk if will be formed on radial location, the cunning that in other words will be formed on the end of first type surface of limit portion 15 of circumferential edges of the first type surface of the glass substrate radial location that the maximal value of (protuberance) exists that jumps at the roughly the same glass substrate of circumferencial direction, the disk set of packing into then can not cause head crash.

Therefore, in the present embodiment, be formed on the whole circumference of glass substrate 10, and to make protuberance in the portion of deviating from 14 be that peaked limit portion 15 is formed on apart from the roughly the same distance in the center of this glass substrate having formed the portion that deviates from 14 that deviates from.Below describe at this point.

The disk that below just is used to make present embodiment describes with the manufacture method of substrate.

Though make disk substrate (specifically as described later) through various operations, but make as the disk of present embodiment situation with substrate (at the peripheral edge portion of first type surface, have the substrate of limit portion 15 that conduct deviates from the summit of portion's (protrusion or subsidence part) 14 apart from the roughly the same distance in the center of this glass substrate) under, grinding step (second grinding step) is very important especially at last.In addition, main grinding condition by above-mentioned last grinding step decides the subsidence part that forms above-mentioned protrusion or above-mentioned relatively tabular surface formation sedimentation at the peripheral edge portion of first type surface.In addition, in the following description, describe with regard to the condition that is used to form protrusion.

Along with the raising of storage density, the height of desired above-mentioned protrusion obviously reduces, and determines most of main cause of its shape, size to depend on the grinding condition of last grinding step.

And the great majority of the various grinding conditions in the last grinding step are influential to shape, the size of above-mentioned protrusion, and wherein especially processing speed (process velocity) and tonnage have influence.

Below, just use the lapping device of planet wheel mode, the last grinding step that the first type surface of glass substrate is ground to describe.Certainly, do not use the lapping device of planet wheel mode can carry out above-mentioned last grinding step yet.For example also can use the lapping device of chip that above-mentioned glass substrate is carried out last grinding step.

In the end in the grinding step, by two first type surfaces that simultaneously utilize grinding pad to push this glass substrate grinding pad and glass substrate are relatively moved and grind above-mentioned glass substrate.At this moment, the process redundancy of unit interval is processing speed, and the pressure of pushing glass substrate is tonnage.

And,, preferably make processing speed in the scope that 0.25 μ m/ branch～0.5 μ m/ divides, and make tonnage in the scope of 8.5Pa～11Pa in order to make the magnetic glass substrate of present embodiment.Because the influence of other grinding conditions is smaller, therefore do not limit, for example under the situation of 2.5 inches disks (Ф 65mm), the hardness that can make grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is 1.0 (μ m).Under the situation of grinding under the condition except above-mentioned condition, the danger of end shape variation or breaking glass panel is arranged.

And, in order to make the disk substrate of present embodiment, to carry out under the finally ground situation at the lapping device that uses the planet wheel mode, the relation from rotating speed and the revolution speed in device of carrier is also extremely important.

In the planet wheel mode, many glass substrates are remained on the carrier.And this maintained glass substrate is with the following thereon crimping grinding pad of carrier.And, under this state, simultaneously revolve round the sun by the rotation of carrier one side, grind above-mentioned glass substrate.That is because the direction that relatively moves of glass substrate and grinding pad is arbitrarily, be average therefore, but it doesn't matter fully with the circumferencial direction of glass substrate.Therefore, jump etc. for the cunning of the outer edge part that is formed on glass substrate, the position of its radial direction, size take place uneven on the position of circumferencial direction.

Therefore, in order to reduce the inequality of this circumferencial direction, preferably the ratio from rotating speed and revolution speed of carrier is set in 0.125～8 the scope.Under the situation of grinding with the condition that surpasses this scope, mostly the jump shape of (protrusion) of the cunning that is formed on the circumferential edges of glass substrate is mixed and disorderly at circumferencial direction.

And, when when seeing this glass substrate with the direction of the first type surface quadrature of above-mentioned glass substrate, in the position of the radial direction that is formed with above-mentioned limit portion under the situation of circumferencial direction inequality, specifically be the circle that forms when for example connecting between the limit portion with line eccentric or form oval, form under the flexuose situation the violent change up and down of generation when the circumferencial direction (trajectory direction) that record-header (magnetic head) scans is reported to the leadship after accomplishing a task with the track that limit portion is linked to each other.In other words, when record-header scans, cross a plurality of limit portion on the disk of high speed rotating, this record-header to float flight unstable.

And along with in recent years record-header low floated quantification, record-header can not be followed this and be changed up and down, and the danger of the obstacle that bumps is arranged.And, under the situation of contact slidingtype hard disk, have that record-header takeoffs, signal quality variation or the danger that causes record-header to damage.

On the other hand, as above-mentioned formation, by making limit portion apart from the roughly the same distance in the center of glass substrate, even the generation cunning jumps or descends, when record-header scanned, as long as always by above the top of limit portion 15, can think did not have to produce the difference of height of the degree of knocking down., expect causing limit portion itself to have difference of height owing to the position of circumferencial direction is different, but compare with the limit portion lifting of generation such as zigzag, this difference of height is significantly little.That is, the height change of only paying attention to the substrate surface on the circumferencial direction is important.

Therefore,,, can reduce roughness, the fluctuating of circumferencial direction, improve flatness in the especially outer edge part of disk with substrate according to the formation of present embodiment.Therefore,, can not upset the posture of floating of magnetic head although the generation cunning jumps or descends yet, even under the situation that makes the disk high speed rotating, the danger that does not also have disk to contact with magnetic head.Like this, can improve reliability when packing disk into disk set tremendously.And, for passing through of the magnetic head in the handling mode, there is not the danger that posture is especially upset or contacted with disk in the outer edge part of disk of floating of magnetic head yet, therefore, record-header can stably pass through the disk end, and is very suitable.

Specifically be on first type surface, to be that the circularity of the circle that forms of maximum limit portion 15 can be in 600 μ m by deviating from protuberance in the portion 14 or sedimentation.Preferably in 400 μ m.Better is in 200 μ m.If circularity reduces (value increases), though then limit portion deviate from big or small identical, but see that at circumferencial direction the size that deviates from neither be roughly the same.In other words, when the section of seeing on the radial location (deviating from the position that portion 14 exists) of the center regulation of glass substrate, if make the glass substrate rotation, the size (for example height of protrusion) that then deviates from the limit portion of portion 14 changes.That is, record-header floats under the situation of flight in the radial location of afore mentioned rules, if this record-header can not be followed the above-mentioned variation that deviates from the size of portion 14, then produces head crash.But,, then can make the big or small relative record head that deviates from big or small roughly the same of circumferencial direction by making circularity in above-mentioned scope.

Be formed on glass substrate the center circular hole be that the concentricity of the circle that forms of maximum limit portion 15 can be in 1200 μ m by deviating from protuberance in the portion 14 or sedimentation.Preferably in 1000 μ m.Better is in 800 μ m.If concentricity reduces (value increases), though then limit portion 15 deviate from big or small identical, see that at circumferencial direction the size that deviates from neither be roughly the same.But by making concentricity in above-mentioned scope, the size that deviates from that then can make circumferencial direction is big or small roughly the same with respect to record-header.

And the size that deviates from is preferably roughly the same at the circumferencial direction of radial location arbitrarily.Consistent by the track that circumferencial direction and limit portion are formed, and make limit portion deviate from big or small roughly the same, can further prevent contacting of disk and magnetic head.At this, " roughly the same " be meant and consider and make the big or small both sides of circularity at above-mentioned scope and the relative disk radial direction of record-header, preferably 0.02mm+1.00mm (width of the micromicron sled of record-header)=1.02mm.

Specifically be, for example disk with substrate on, will deviate from portion 14 at circumferencial direction under 30 ° of situations of measuring 12 points, the variation that deviates from portion's size can be below 5nm.By in such scope, can further obtain effect of the present invention really.

And, as mentioned above, if record-header can not be followed the variation of the above-mentioned size that deviates from, head crash takes place then.Be specifically described, record-header is under the situation of floating flight on the disk at this point, even this record-header under the big situation of the size variation that deviates from, can be followed under its variation ratio little (mild) situation.But, taking place then to cause collision under the big situation that deviates from variation between the small flying distance.That is, the disk of present embodiment is particularly useful for the situation that magnetic head floats flight at a high speed with substrate.More specifically be that the disk of present embodiment preferably makes disk use with the glass substrate on the disk set of the rotation of the rotating speed more than the 5400rpm as being used to be loaded in substrate.It is no problem certainly to be loaded on the disk set with the rotation of the rotating speed more than the 5400rpm, especially under the situation of the disk set that makes the disk high speed rotating, compare with substrate with non-disk of the present invention, use the disk of present embodiment very obvious with the effect of substrate.

And the disk of present embodiment preferably uses as following glass substrate with substrate, and this glass substrate is used to be loaded in the disk set that magnetic head moves in the portion that deviates from 14 of the circumferential edges that is present in this glass substrate with the linear velocity of 20.0m/ more than second.

And it is the following disk of 3～4nm that the disk of present embodiment preferably is used to touch end height (TDH) with substrate.If it is low to touch end height, then, cause collision easily being formed under the big situation of the variation that deviates from the above-mentioned glass substrate.But, by using the disk substrate of present embodiment, can make the variation of the portion of deviating from 14 littler than existing, therefore,, also can suppress head crash even reduce the floatation volume of magnetic head (record-header).

And it is 200GBit/inch that the disk of present embodiment is preferred for recording density with substrate ²The disk of above high record density, more preferably being used for recording density is 250GBit/inch ²The disk of above high record density.Under the situation of such high record density, because the floatation volume of record-header can be littler, so, can suppress collision by using the disk substrate of present embodiment.In addition, be used for recording density less than the glass substrate of above-mentioned disk or be used to make touch end height greater than the disk of above-mentioned disk with the also applicable certainly disk substrate of the present invention of substrate.

In addition, the disk of present embodiment has smooth first type surface, end face with substrate and is present in fillet surface between this first type surface and the end face, and the peripheral edge portion of first type surface exist to this peripheral edge portion beyond the portion that deviates from 14 that deviates from of the direction of tabular surface quadrature, and, this disk substrate is a circular plate type, under the situation of the first type surface of vertical transparency substrate, the above-mentioned degree that deviates from also can be present in apart from the position of the roughly the same distance of central part of this glass substrate for the maximum above-mentioned maximum point (limit portion 15) that deviates from portion 14.

And, under the situation of the first type surface of vertical transparency substrate, the maximum point that deviates from portion 14 also can be present in central part with this glass substrate be benchmark, with respect to the distance of the profile of this glass substrate in 92.0～97.0% scope.

And under the situation of the first type surface of overlooking above-mentioned glass substrate, the limit portion 15 of above-mentioned protrusion surrounds above-mentioned first type surface circularly, and the circularity of the circle that is formed by above-mentioned limit portion 15 is preferably in 600 μ m.

And, above-mentioned glass substrate has circular hole at central part, under the situation of the first type surface of overlooking above-mentioned glass substrate, the limit portion 15 of above-mentioned protrusion surrounds above-mentioned first type surface circularly, and the concentricity of circle that is formed by above-mentioned limit portion 15 and the circle that formed by the circular hole of above-mentioned central part is preferably in 1200 μ m.

And, it is the glass substrate of circular plate type, above-mentioned glass substrate has smooth first type surface, end face and is present in fillet surface between above-mentioned first type surface and the end face, under the situation of the first type surface of overlooking above-mentioned glass substrate, between above-mentioned first type surface and fillet surface, have subsidence part, can make the locational above-mentioned subsidence part of the center gauge set a distance that leaves above-mentioned glass substrate roughly the same apart from the degree of depth of first type surface with respect to above-mentioned first type surface sedimentation.

And the disk of present embodiment preferably carries out chemical enhanced at least to end face with substrate, strengthen more preferred to substrate front (whole surface).In other words, above-mentioned disk more preferably forms compressive stress layers on its surface with substrate.Especially being installed in high speed rotating (for example 10000rpm) makes above-mentioned disk with under the situation on the disk set of substrate rotation or be installed under the situation on the disk set that uses as mobile purposes, require glass substrate to have resistance to impact, therefore, preferably form compressive stress layers at glass baseplate surface.In addition, chemical enhanced being meant here by glass substrate is contacted with the chemical enhanced processing that contains chemical enhanced salt night, a part of ion and the ion footpath contained in the glass substrate are replaced greater than the ion in the chemical enhanced treating fluid of this ion, thereby carry out the processing of hardened glass substrate.

(disk)

Can be by forming the disk that magnetic film is made present embodiment on substrate at above-mentioned disk.Because formation magnetic film on above-mentioned disk is used substrate, therefore, the shape of the first type surface of this disk is subjected to the very big influence of this glass substrate.That is,, need the shape of the first type surface of the above-mentioned glass substrate of raising in order to improve the shape of the first type surface on the disk.Therefore, use substrate as the disk substrate, can make and improve the especially disk of the shape of peripheral edge portion of first type surface by using the described disk of present embodiment.In addition, the manufacture method of disk is well-known, in this description will be omitted.

And, the disk of present embodiment also can be loaded in that magnetic head is packed into respect to first type surface through its outward flange and the disk set of the handling mode that unloads on disk.Because therefore the flatness height of the outer edge part of glass substrate can form the disk that is suitable for handling mode.

And the magnetic disc substrate of present embodiment also can be to be used to be loaded in make disk at least with the disk on the disk set of the rotation of the rotating speed more than the 5400rpm.Also the speed of being suitable for is the disk set of the above speed of 10000rpm.This be because: because the flatness height of the outer edge part of glass substrate, even therefore under the situation of high speed rotating, the danger that does not also have disk to contact, reliability height with magnetic head.

And the disk of present embodiment also can be a contact slidingtype recording medium (contact history formula recording medium).Contact slidingtype recording medium is owing to be to read and write in that record-header contact with disk under the state that slides, and therefore, as mentioned above, uses the flatness of circumferencial direction of the especially outer edge part of substrate by the raising disk, can prevent that record-header from takeofing.Like this, can improve signal quality, prevent that record-header from damaging.

(disk set)

By loading above-mentioned disk, can form disk set (hard disk drive).And, loaded above-mentioned disk is particularly suitable for being undertaken by high speed rotating recording of information regeneration with the disk set of substrate situation.

In addition, though be that the center describes with above-mentioned disk with the peripheral end face of substrate, interior all end faces also are formed as described above the portion of deviating from 14.And, this deviate from the portion 14 protuberance for maximum limit portion 15 certainly preferably apart from the roughly the same distance in the center of this glass substrate.

(embodiment)

Below just be suitable for disk of the present invention and describe with the embodiment of the manufacture method of substrate and disk.This disk is made as the disk with 3.5 inches disks (Ф 89mm), 2.5 inches disks (Ф 65mm), 1.0 inches disks (Ф 27.4mm), 0.8 inch disk (Ф 21.6mm), 1.8 inches disks (Ф 48mm) isotactic setting shape with substrate and disk.

(1) the shape manufacturing procedure and first polishing process

, at first, (grinding) polished on the surface of plate glass be processed to form base glass material with in the manufacture method of substrate at the disk of present embodiment, cut off this base glass material and cut out the glass disk.Plate glass can use various plate glass.This plate glass is material with the melten glass for example, can utilize well-known manufacture methods such as die pressing or float glass process, glass tube down-drawing, multistage stretching method, fusion method to make.Wherein, if use die pressing, can make plate glass at an easy rate.The material of plate glass can be used amorphous glass, glass ceramics (glass ceramics).The material of plate glass can use sillico aluminate glass, soda-lime glass, borosilicate glass etc.Especially amorphous glass, can implement chemical enhanced, and, can offer the flatness and the good disk substrate of substrate intensity of first type surface, in this, preferably use sillico aluminate glass.

In the present embodiment, adopt the direct pressing mold that has upper die and lower die, intermediate die, the sillico aluminate glass of fusion is shaped to plate-like, obtained the plate glass of amorphous.In addition, as sillico aluminate glass, adopt and contain with SiO ₂: 58～75 weight %, Al ₂O ₃: 5～23 weight %, Li ₂O:3～10 weight %, Na ₂O:4～13 weight % are the chemically reinforced glass of major component.

Then, two first type surfaces of this plate glass are polished processing, become the base glass material of plate-like.This polishing processing is with the polishing both surfaces device with planetary gears, carries out with the alumina series free abrasive.Specifically, make polished land, the grinding fluid that contains free abrasive is supplied on the first type surface of plate glass, they are relatively moved, polish processing from pushing the two sides of plate glass up and down.Through this polishing processing, the base glass material that obtains having planar major surface.

(2) cut out operation (coring, shaping processing, chamfering)

Then, base glass material is cut off, cut out discoid glass substrate from this base glass material with diamond tool.Then, use diamond drill machine cylindraceous again, the central part formation endoporus at this glass substrate becomes circular glass substrate (coring).Then, utilize all end faces and peripheral end face in the diamond wheel grinding, the chamfer machining of stipulating (processing, chamfering are shaped).

(3) second polishing processing

Then, with first polishing process similarly, two first type surfaces of the glass substrate that obtains are carried out the second polishing processing.By carrying out this second polishing processing, can remove promptly cut out the trickle concaveconvex shape that is formed on the first type surface in operation, the end surface grinding operation in preceding operation in advance, make follow-up grinding step to finish at short notice to first type surface.

(4) end surface grinding operation

Then, with the brush Ginding process, peripheral end face and interior all end faces of glass substrate carried out mirror ultrafinish.At this moment, grind abrasive particle and be to use the slurry (free abrasive) that contains the cerium oxide abrasive particle.

Then, water cleans the glass substrate of having finished the end surface grinding operation.Through this end surface grinding operation, the end face of glass substrate is processed to the mirror status that can prevent that sodium, potassium from separating out.

(5) first type surface grinding step

As the first type surface grinding step, implement first grinding step earlier.The fundamental purpose of this first grinding step is to remove scar, the distortion that remains in aforementioned polishing process on the first type surface.In this first grinding step, by two sides lapping device, adopt the hard resin lap with planetary gears, carry out the grinding of first type surface.Lapping compound adopts the cerium oxide abrasive particle.

The glass substrate of this first grinding step that is through with, be impregnated into successively in each rinse bath of neutral detergent, pure water, IPA (isopropyl alcohol), clean.

Then, as the first type surface grinding step, implement second grinding step.The purpose of this second grinding step is that first type surface is finish-machined to mirror-like.In this second grinding step, by two sides lapping device, adopt flexible foamed resin ground tool with planetary gears, carry out the mirror ultrafinish of first type surface.Lapping compound adopts the cerium oxide abrasive particle thinner than the cerium oxide abrasive particle that uses in first grinding step.

The glass substrate of this second grinding step that is through with, be impregnated into successively in each rinse bath of neutral detergent, pure water, IPA (isopropyl alcohol), clean.In addition, each rinse bath has been applied ultrasound wave.

(6) chemical enhanced operation

Then, the glass substrate to be through with above-mentioned polishing process and grinding step carries out chemical enhanced.Chemical enhanced is the chemical enhanced solution of preparing to have mixed potassium nitrate (60%) and sodium nitrate (40%), should be heated to 400 ℃ by chemical enhanced solution, and the glass substrate after will cleaning is preheating to 300 ℃, floods about three hours in chemical enhanced solution.When this floods, chemical enhanced for the whole surface of glass substrate is carried out, to keep the mode of a plurality of glass substrates at end face, carry out at the state that is accommodated on the retainer.

Like this, by carry out dip treating in chemical enhanced solution, the lithium ion on glass substrate top layer and sodion are replaced as sodion and the potassium ion in the chemical enhanced solution respectively, have strengthened glass substrate.The thickness that is formed on the compressive stress layers on glass substrate top layer is approximately 100 μ m to 200 μ m.

The glass substrate of the chemical enhanced processing that is through with is immersed in 20 ℃ the tank and cools off rapidly, kept about ten minutes.Then, the substrate that cools off rapidly being through with is immersed in to be heated in about 40 ℃ concentrated sulphuric acid and cleans.Then, the glass substrate that will carry out sulfuric acid cleaned is impregnated into successively in each rinse bath of pure water, IPA and cleans.

As mentioned above, by implement first polishing process, cut out operation, second polishing process, end surface grinding operation, first and second grinding steps and chemical enhanced operation, obtain the disk substrate of smooth and level and smooth high rigidity.

(7) check operation

Check the shape of resulting disk with the outer edge part of substrate.Check operation by measuring operation and judging that operation constitutes, in measuring operation, a plurality of positions measurement of the circumferencial direction of glass substrate is deviated from value and limit portion 15; In judging operation, based on measured a plurality ofly deviating from value and limit portion 15, judging whether glass substrate is certified products.

(8) disk manufacturing process

On the two sides of having passed through the glass substrate that above-mentioned operation obtains; by carry out the film forming of adhesion layer that the Cr alloy forms, soft ferromagnetic layer that the CoTaZr alloy forms, basalis that Ru forms, perpendicular magnetic recording layer that CoCrPt base alloy forms, protective seam that hydrocarbon forms, lubricating layer that PFPE forms successively on the surface of glass substrate, make perpendicular magnetic recording disk.In addition, this formation is the vertical disk of an example (PMR: formation perpendicular magnetic recording), but also can be used as horizontal disk (LMR: horizontal magnetic recording) constitute magnetosphere etc.Like this, the outer edge part that can make first type surface also has the disk of height flatness.

(9) disk set manufacturing process

And,, make disk set by above-mentioned disk groups is installed in the device.In addition, the formation of disk set is well-known, therefore, specifies in this omission.

(the 3rd embodiment)

Grinding condition shown below is applicable to second grinding step of above-mentioned (5) first type surface grinding step, makes disk with substrate, disk, disk set.In addition, in the 3rd embodiment, make 2.5 inches disks (Ф 65mm).The concrete grinding condition of this 3rd embodiment and above-mentioned first embodiment similarly, the hardness of grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is that 1.0 (μ m), processing speed are that 0.30 (μ m/ branch), tonnage are 9 (Pa).(that is, the 3rd embodiment of second embodiment of the present invention is illustrated as first embodiment in first embodiment of the present invention.)

(the 4th comparative example)

Except the grinding condition in above-mentioned second grinding step being made as following condition, utilize above-mentioned manufacture method to make disk substrate, disk, the disk set of the 4th comparative example.The concrete grinding condition of the 4th comparative example and second comparative example similarly, processing speed is that 0.45 (μ m/ branch), tonnage are 8.0 (Pa).(that is, the 4th comparative example is illustrated as second comparative example in first embodiment of the present invention.)

(comparison of the 3rd embodiment and the 4th comparative example)

Be present in the disk shown in the 3rd embodiment and the 4th comparative example, made shape by method inspection shown below with the limit portion 15 of the first type surface circumferential edges of substrate.

(A) surface configuration is specific

In order to investigate the shape (end shape) of disk, used light interference type surface profile measuring instrument (OptiFlat (production of Phase Shift Technology company)) with the first type surface circumferential edges of substrate.Its result, the end shape that can find out the glass substrate of the 3rd embodiment, the 4th comparative example is the sliding shape that jumps.And, measure sliding in shape the summit (limit portion 15) of jumping apart from the distance at glass substrate center from this measurement result.And, for the displacement of the circumferencial direction of investigating above-mentioned vertex position, make glass substrate 30 ° of the each rotations of circumferencial direction, the position of measuring above-mentioned summit is totally 12 points.The result of this moment as shown in Figure 6.In addition, Fig. 6 represents to measure the result of the radial location of sliding the limit portion (sliding jumping a little) 15 that jumps.

Its result as shown in Figure 6, from the center of glass substrate, the disk that is formed on the 3rd embodiment is positioned at roughly the same position (distance) with the limit portion 15 of the first type surface circumferential edges of substrate, specifically be, from the center of glass substrate, be the center with 30.6mm, be positioned at ± scope of 0.2mm.And under the situation of the 4th comparative example, be the center with 30.6mm, be positioned at ± scope of 1.4mm.

In addition, the disk of the 3rd embodiment is 0.40 (mm) with the circularity of substrate, and concentricity is 1.07 (mm).And the disk of the 4th comparative example is 2.60 (mm) with the circularity of substrate, and concentricity is 5.68 (mm).And the height of limit portion 15 (deviating from value) is roughly the same in the formation of the 3rd embodiment and the 4th comparative example.

(B) the loading and unloading test relatively

After having made disk at the 3rd embodiment and the 4th comparative example respectively and having formed magnetospheric disk on substrate, make disk set, carry out rotating speed and be the loading and unloading test under 10000 situations of changeing.The floatation volume of the record-header of this moment is 9～10nm.Its result, the 3rd embodiment 1,000,000 times repeatedly also do not bump, and the 4th comparative example bump after loading and unloading 600,000 times repeatedly.In addition, in the 3rd embodiment, be under the situation of 5400rpm and 7200rpm at rotating speed, load and unload 1,000,000 times repeatedly and also do not bump.

Although the value that deviates from value of the 3rd embodiment and the 4th comparative example is roughly the same, being formed in to produce when carrying out coasting test with high speed rotating of the 4th comparative example knocked down.And the formation of embodiment does not produce and knocks down.Even this may be that the cunning of (not little) jumps owing to take place greatly, because circularity or concentricity height (being worth little), the then variation of the substrate surface of circumferencial direction (roughness, fluctuating) is few.And, find out that from a large amount of test findings preferably in 600 μ m, concentricity is preferably in 1200 μ m for circularity.

According to this result, as shown in the present, it is very important making the radial location of limit portion (summit of protrusion) 15 of the portion that deviates from 14 of the first type surface circumferential edges that is present in glass substrate roughly the same at circumferencial direction.

(C) influence of end shape

Influence with regard to the height of the limit portion 15 of circumferencial direction is investigated.Investigated the influence that the radial location of the limit portion (summit of protrusion) 15 of the portion that deviates from 14 of the first type surface circumferential edges that is present in glass substrate produces with the height change on the summit of the circumferencial direction of substrate (above-mentioned the 3rd embodiment) at the roughly the same disk of circumferencial direction.And, prepared circumferencial direction the summit height change greater than above-mentioned the 3rd embodiment other disk with substrate as the 5th comparative example.Make tonnage in the last grinding step and processing speed and above-mentioned the 3rd embodiment differently make the disk substrate of the 5th comparative example.Specifically be, the disk of the 5th comparative example is identical with the situation of above-mentioned first comparative example with substrate, and the hardness that makes grinding pad is that the particle diameter of 85 (askerC hardness), abrasive material is that 1.0 (μ m), processing speed are that 0.60 (μ m/ branch), tonnage are that 12 (Pa) make.(that is, the 5th comparative example is illustrated as first comparative example in first embodiment of the present invention.)

And for the variation of the height of the circumferencial direction of investigating above-mentioned two glass substrates, the maximum of having measured any point-to-point transmission of two substrates deviates from value.Specifically be that the measurement range (R1 of Fig. 2, R2) that maximum deviates from value has determined to see first type surface circumferential edges that is formed on glass substrate and the measurement range that changes in the different limit portion 15 of the height of circumferencial direction.At this, be respectively the point (R2) of 29.9mm (R1), 31.5mm apart from the distance of substrate center, measuring equipment uses light interference type surface profile measuring instrument (MicroXam (production of Phase Shift Technology company)).And, make glass substrate 30 ° of the each rotations of circumferencial direction, the position of measuring above-mentioned summit is totally 12 points.In addition, MicroXam compares with above-mentioned OptiFlat, though the narrow resolution height of measured zone.

That is, the maximum measured of said method deviates from the size that deviates from the summit (limit portion 15) that value representation connects straight line and the above-mentioned protrusion of above-mentioned R1 and R2.And its result as shown in Figure 7.

As shown in Figure 7, the 3rd embodiment compares with the 5th comparative example, and the variation of the height of the circumferencial direction of glass substrate is little.Specifically be, the change difference of the 3rd embodiment is 2.86nm, and the change difference of the 5th comparative example is 16.10nm.

After having made disk at the 3rd embodiment and the 4th comparative example respectively and having formed magnetospheric disk on substrate, make disk set, load and unload test.Specifically being, the floatation volume of record-header is set at 9～10nm, is to test under two kinds of situations of 5400rpm and 7200rpm at the rotating speed that makes disk.

Its result is under the situation of the disk of the 3rd embodiment and the 4th comparative example, even with rotating speed 1,000,000 loading and unloading repeatedly of 5400rpm, also do not bump.The disk of the 5th comparative example bumps in 2,000,000 loading and unloading tests.

Recognize according to this result, limit portion 15 in the circumferencial direction of glass substrate, its position at radial direction identical and short transverse with low uncertainty to making the disk high speed rotating the most favourable.

More than, describe with regard to preferred second embodiment of the present invention with reference to accompanying drawing, but the present invention is not limited to this embodiment certainly.If those skilled in the art, various modifications in the scope that then obviously can expect in claim, putting down in writing or correction example, these also belong to technical scope of the present invention certainly.

For example in the above-described embodiments, substrate of the present invention can use glass (amorphous glass or glass ceramics (glass ceramics).Material to plate glass can use sillico aluminate glass, soda-lime glass, borosilicate glass etc. to be illustrated.But the present invention is owing to be about the shape of substrate, therefore without limits to the material of substrate, even the substrate that forms of other materials such as aluminium for example also can suitably use the present invention.But as mentioned above, especially in portable equipment, preferably compare the flatness of substrate surface and the good glass substrate of substrate intensity with aluminium base.

Disk of the present invention also can be following formation with substrate, promptly, be first type surface, the end face with general planar, the disk substrate that is formed on the fillet surface between above-mentioned first type surface and the end face, the tabular surface protuberance beyond the circumferential edges of above-mentioned first type surface has this circumferential edges relatively or the portion that deviates from 14 of sedimentation, the above-mentioned portion 14 that deviates from forms continuously at the circumferencial direction of first type surface, and the position of the limit portion 15 that the above-mentioned protuberance that deviates from the portion 14 is a maximum is apart from the roughly the same distance in the center of this substrate.

And the above-mentioned portion 14 that deviates from can be formed on the neighboring of first type surface that endoporus is formed on the discoidal disk at center, also can be formed on inner periphery, also can be formed on both sides.And, in the present invention, deviating under the situation that portion 14 is formed on inner periphery and neighboring both sides, at least one side's the portion that deviates from 14 is that above-mentioned shape gets final product, but preferably the fast neighboring of the linear velocity of record-header is above-mentioned shape.

The present invention can be used as the disk that is used for magnetic recording media with substrate and use the disk of this substrate to use.

Claims (29)

1. disk substrate, it is the substrate of circular plate type, have general planar first type surface, end face, be formed on fillet surface between described first type surface and the end face and the circumferential edges place in first type surface the portion that deviates from respect to protuberance of the tabular surface beyond this circumferential edges or sedimentation, described deviate from portion deviate from size about equally in the whole circumference of this substrate.

2. disk substrate as claimed in claim 1 is characterized in that, the described size that deviates from is roughly the same at the circumferencial direction of radial location arbitrarily.

3. disk substrate as claimed in claim 1 is characterized in that, to substrate, at circumferencial direction under 30 ° of described situations that deviate from portion of measuring 12 points, deviate from being changed to below the 5nm of size.

4. disk substrate as claimed in claim 1 is characterized in that, described protuberance or the sedimentation that deviates from the portion is the maximum limit portion distance roughly the same apart from the center of this substrate.

5. disk substrate as claimed in claim 1 is characterized in that, on described first type surface, to deviate from protuberance in the portion or sedimentation be that the circularity of the circle that forms of maximum limit portion is in 600 μ m by described.

6. disk substrate as claimed in claim 1 is characterized in that,

This substrate has circular hole at the center,

At described first type surface, to deviate from protuberance in the portion or sedimentation be that the concentricity of the circle that forms of maximum limit portion and described circular hole is in 1200 μ m by described.

7. disk substrate as claimed in claim 1 is characterized in that, this substrate be carry magnetic head pack into through the outward flange of disk, with respect to the first type surface of disk and the disk set of the handling mode that unloads on the disk substrate.

8. disk substrate as claimed in claim 1 is characterized in that, this substrate is to be used to carry make disk with the disk substrate on the disk set of the rotation of the rotating speed more than the 5400rpm at least.

9. a disk is characterized in that, forms magnetosphere at least on each described substrate in claim 1 to 8.

10. disk as claimed in claim 9 is characterized in that, touches end height below 4nm.

11. disk as claimed in claim 9 is characterized in that, recording density is 200GBit/inch ²More than.

12. a disk set carries each described disk in the claim 9 to 11 and forms.

13. disk substrate, it is the substrate of circular plate type, have first type surface, end face, be formed on fillet surface between described first type surface and the end face and the circumferential edges place in described first type surface and form the portion that deviates from that deviates from of protuberance or sedimentation with respect to the tabular surface beyond this circumferential edges, the described shape that deviates from portion is identical on the whole circumference of this substrate.

14. a disk substrate is the substrate of circular plate type, the substrate of described circular plate type has the first type surface of general planar, end face and the fillet surface between described first type surface and end face,

Between described first type surface and fillet surface, have protrusion with respect to described first type surface protuberance,

Under the situation of the first type surface of overlooking described circular plate type substrate, described protrusion surrounds described first type surface with roughly the same height.

15. a disk substrate is the substrate of circular plate type, the substrate of described circular plate type has the first type surface of general planar, end face and the fillet surface between described first type surface and end face,

Under the situation of the first type surface of the substrate of overlooking described circular plate type, between described first type surface and fillet surface, subsidence part with respect to described first type surface sedimentation forms circle, and the locational described subsidence part of center gauge set a distance that is in the substrate that leaves described circular plate type is roughly the same apart from the degree of depth of first type surface.

16., it is characterized in that this disk substrate is the substrate that uses as the substrate of the disk of corresponding DFH (dynamically flying height) magnetic head as each described disk substrate in the claim 1,13,14,15.

17., it is characterized in that this substrate is to carry out the glass substrate of chemical enhanced processing as each described disk substrate in the claim 1,13,14,15, and be the glass substrate that has ion exchange layer on the surface of at least a portion of substrate surface,

The bed thickness of ion exchange layer is thicker than first type surface at end face.

18. disk substrate, it is the substrate of circular plate type, have general planar first type surface, end face, be formed on fillet surface between described first type surface and the end face and the circumferential edges place in described first type surface the portion that deviates from respect to the protuberance of the tabular surface beyond this circumferential edges

The described portion of deviating from is formed on the whole circumference of this substrate,

The described protuberance that deviates from the portion is in apart from the roughly the same distance in the center of this substrate for maximum limit portion.

19. disk substrate as claimed in claim 18 is characterized in that, the limit portion that deviates from the portion of protuberance deviates from the whole circumference of portion at this, from the center of this substrate to the distance of the radial direction of external diameter, be in 92.0～97.0% the scope.

20. disk substrate as claimed in claim 18 is characterized in that, on described first type surface, the circularity of the circle that is formed by described limit portion is in 600 μ m.

21. disk substrate as claimed in claim 18 is characterized in that this substrate has circular hole at the center,

At described first type surface, the circle that is formed by described limit portion and the concentricity of circular hole are in 1200 μ m.

22. disk substrate as claimed in claim 18 is characterized in that, the described portion of deviating from comprise the circumferential edges that is formed on described first type surface with respect to the protuberance of the tabular surface beyond this circumferential edges with and/or sedimentation,

The described size that deviates from that deviates from the portion is roughly the same on the whole circumference of this substrate.

23. disk substrate as claimed in claim 22 is characterized in that, in the described portion that deviates from, the variation of the described size that deviates from is below 5nm.

24. disk substrate as claimed in claim 18 is characterized in that, this substrate be carry magnetic head pack into through the outward flange of disk, with respect to the first type surface of disk and the disk set of the handling mode that unloads on the disk substrate.

25. substrate as claimed in claim 18 is characterized in that, this substrate is to be used to carry make disk with the disk substrate on the disk set of the rotation of the rotating speed more than the 5400rpm at least.

26. a disk is characterized in that, forms magnetosphere at least on each described substrate in claim 18 to 25.

27. disk as claimed in claim 26 is characterized in that, touches end height below 4nm.

28. disk as claimed in claim 26 is characterized in that, recording density is 200GBit/inch ²More than.

29. a disk set carries each described disk in the claim 26 to 28 and forms.

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