JP4384591B2 - Surface polishing method - Google Patents

Description

  The present invention relates to a surface polishing method for an object to be processed, and more particularly to a surface polishing method for an object to be processed in manufacturing a liquid crystal display substrate, a magnetic recording medium substrate, a photomask, a device, and the like.

The improvement in recording density (surface density) of magnetic recording has been very rapid, and during the last 10 years, a rapid improvement of 50% to 200% has been made continuously. 70 Gbt / inch ² (about 10.9 Gbit / cm ² ) products are shipped at the mass production level, and the areal recording density of 160 Gbit / inch ² (about 24.8 Gbit / cm ² ) has been reported at the laboratory level. Yes. The surface recording density at the mass production level corresponds to 80 Gbytes per platter in a 3.5 inch HDD, and corresponds to 40 Gbytes per platter in a 2.5 inch HDD. Recording density is expected to continue to improve. Furthermore, it is considered that the diameter of the magnetic recording substrate will be reduced in the future as the recording density increases.

In order to reduce the diameter and increase the recording density per unit area, it is necessary to reduce the glide height of the magnetic recording head. Specifically, the required glide height is conventionally about 30 nm, but is expected to be 10 nm or less in the future. Of course, the lowering of the glide height makes it essential to improve the flatness of the substrate surface. What attracts attention as the content of flatness is the waviness of the substrate surface, which is expressed as webiness or micro-webiness in the magnetic recording medium industry. The webiness represents a relatively large swell of 5 mm or less, and the microwebness represents a swell of a relatively narrow range of 2 mm or less. In the present invention, these are collectively referred to as webiness. When this webiness deteriorates, the glide height of the head cannot be lowered. If it cannot be lowered, it will be difficult to improve the recording density. Therefore, it is no exaggeration to say that the key to improving the recording density of magnetic recording media in the future is to improve the webiness. Note that Patent Document 1 discloses a polishing finish of a wafer using a double-side polishing apparatus.
JP-A-5-169365

  The present invention provides a surface polishing method for improving the webiness of an object to be processed in the method of surface polishing an object to be processed.

As an aspect of the present invention, there is provided a planar polishing method for polishing both surfaces of an object to be processed disposed in a through-hole of a processing carrier to a target thickness using a polishing pad, A flat polishing method characterized in that a correction plate having a thickness of 0.8 to 1.0 times the target thickness is provided, and the polishing pad has a hardness of 70 or more, wherein the correction plate comprises: Provided is a surface polishing method comprising at least one selected from the group consisting of brass, SUS, epoxy-impregnated glass, iron, copper, aluminum, nickel and carbon .
As a reference aspect, there is provided a planar polishing method for polishing both surfaces of an object to be processed disposed in a through hole of a processing carrier to a target thickness using a polishing pad, wherein the processing carrier has a target thickness of 0.8. Provided is a planar polishing method having a thickness of not less than twice and not more than 1.0 times, wherein the polishing pad has a hardness of 70 or more.

  According to the processing method of the present invention, the webiness of the workpiece can be improved. For example, when the planar polishing method according to the present invention is applied to the production of a magnetic recording medium, the glide height of the head can be lowered because the webiness of the magnetic recording medium substrate is improved. The recording density per unit area can be improved.

Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
The surface polishing method according to the present invention can be applied to the surface polishing of any object to be processed, and is particularly preferably applied to the surface polishing of an object for which improvement in webiness is desired. More specifically, the present invention is preferably applied to planar polishing of an object to be processed such as a liquid crystal display glass substrate, a magnetic recording medium substrate, a photomask substrate, and a device substrate.
In the present invention, the surface polishing means that the front and back surfaces are polished in parallel. As a form of polishing, polishing by floating (the object to be processed is moving in the surface plate without being fixed during polishing), and with a support fixed type such as a suction pad or wax as in normal single-side polishing, Absent.

The shape of the object to be processed may be any shape such as a circular shape, a pseudo-circular shape, an annular shape, an elliptical shape, or a polygonal shape, and is not particularly limited, but a plate shape is preferable. Moreover, it is preferable that at least one surface that is a surface to be processed of the object to be processed is substantially a flat surface. In this case, it is because the plane polishing process by single-sided polishing or double-sided polishing can be performed suitably.
The workpiece is preferably made of glass, B, C or Si, or a group consisting of Fe, Cr, Ni, Cu, Co, Al, Sn, Mo, W, Ta, Ti, Nb, C, B and Si. It may be a single metal or two or more alloys selected, and may be coated with this material, but should be appropriately set according to the purpose of the surface polishing, and is particularly limited It is not a thing.

The target thickness of the object to be processed, that is, the thickness of the object to be processed desired after the surface polishing is to be set as appropriate according to the purpose of the surface polishing, and is not particularly limited. Specifically, although not particularly limited, the target thickness of the object to be processed is 0.05 to 5 mm when applied to manufacture of a magnetic recording medium, and when applied to manufacture of a photomask. 0.05 to 5 mm, preferably 0.05 to 5 mm when applied to device manufacture.
Further, the initial thickness of the object to be processed, that is, the thickness of the object to be processed before the surface polishing process should be appropriately set according to the purpose of the surface polishing process, and is not particularly limited. Specifically, although not particularly limited, the initial thickness of the workpiece is 1.01 to 1.50 times the target thickness of the workpiece, or 1 from the target thickness of the workpiece. It is preferable to be larger by ~ 1000 μm.

The polishing apparatus used in the present invention has an upper and lower polishing mechanism that can polish the surface of an object to be processed from above and below, and can polish the surface of the object to be processed by sliding or rotating.
The vertical polishing mechanism has, for example, a vertical movement shaft and operates to rotate by a drive motor or the like. The rotating mechanisms are preferably synchronized, and in some cases, the rotating mechanism may have a mechanism that can change or reverse the rotational force, and is normally reversely rotated up and down.
The vertical polishing mechanism preferably includes a rotating disk (sliding disk) and a rotating shaft, and is equipped with a polishing pad. Between this upper and lower plates, a processing carrier with an object to be processed is installed, fitted into the inner and outer gears, and the processing carrier is rotated and revolved, and the object to be polished is polished by following not fixed to the support. To do.

The processing carrier used in the present invention is a mechanism for holding and polishing the workpiece by transmitting the rotational force of the abrasive to the workpiece when polishing the workpiece.
The processing carrier is not particularly limited as long as it has a shape that can be polished flat, but is preferably a plate-like one having a through-hole, and a workpiece to be processed is installed in the through-hole and protruded from the through-hole. Both sides are polished. For example, if the workpiece is cylindrical, the diameter of the through hole is larger than the diameter of the workpiece.
The processed carrier preferably includes one or more selected from the group consisting of brass, SUS, epoxy-impregnated glass, iron, copper, aluminum, nickel, and carbon, and may be coated with this material.
The thickness of the processed carrier is not particularly limited, but is preferably 0.1 to 300 mm depending on the thickness of the workpiece. In the first aspect of the present invention, the thickness of the processed carrier is preferably 0.8 to 1 times the target thickness of the workpiece. In the second aspect of the present invention, when the processing carrier also functions as a correction plate, it is preferably 0.8 to 1 times the target thickness of the workpiece, and when the processing plate does not function as a correction plate. It becomes thinner than the thickness of the correction plate.

According to the present invention, the workpiece is placed in a through hole (for example, a hole) of the processing carrier, and a necessary amount of the correction plate is disposed in the through hole of the processing carrier as necessary. The polishing pad is preferably installed on the upper and lower portions of the object to be processed, and the object to be processed is polished by sliding or rotating while inserting an abrasive between the object to be processed and the polishing pad.
It is desirable to adjust the polishing sliding speed or rotation speed as appropriate so that the surface state of the object to be processed is obtained.

According to the reference aspect, there is provided a planar polishing method for polishing both surfaces of an object to be processed disposed in a through hole of a processing carrier to a target thickness using a polishing pad, wherein the processing carrier has a target thickness 0.8 times the target thickness. A planar polishing method having a thickness of 1.0 times or less and a polishing pad having a hardness of 70 or more is provided.
For example, when a substrate which is an object to be processed having an initial thickness of 0.53 mm before polishing is polished to a target thickness of 0.50 mm, the substrate is disposed in a through-hole of a processing carrier having a thickness of 0.50 mm, and the hardness is 70 By polishing with the above polishing pad for a predetermined time, a 0.50 mm substrate with improved webiness can be obtained.

Normally, the pad surface of the polishing pad is not flattened only by being affixed to the surface plate of a polishing machine. If the workpiece is polished as it is, the substrate will have a large webiness. Therefore, after the polishing pad is attached, a correction plate is used to smooth the polishing pad surface. The correction can be performed using a correction carrier with diamond pellets, a SUS correction plate, a glass correction plate, or the like.
In addition, after the polishing of the object to be processed is performed several times, the object to be processed having improved webiness can be obtained by correcting the unevenness on the polishing pad. A polishing pad with high hardness is used to efficiently scrape the unevenness of the surface to be processed and improve the webiness of the processed object after polishing. This is because there is a problem in which a fluff is generated, which deteriorates from the web immediately after the correction. The correction can be performed using a correction carrier with diamond pellets, a SUS correction plate, a glass correction plate, etc., but since there are no large irregularities as in the initial correction, correction with the SUS correction plate and the glass correction plate is possible. Thus, the webiness of the workpiece can be improved again.
According to the reference aspect, it is possible to correct the surface state of the polishing pad as well as the workpiece. The reference aspect and the aspect of the present invention may be combined with the above-described correction of the polishing pad by the correction plate before the start of polishing and the correction of the polishing pad by the correction plate after the start of polishing.

FIG. 1 shows a conceptual diagram as a specific example of the reference mode. 1A is before polishing, and FIG. 1B is after polishing. The workpiece 1 is polished by the polishing pads 3 a and 3 b, and at the same time, the polishing carrier is also corrected by the processing carrier 2. For comparison, FIG. 2 shows a conceptual diagram of a conventional mode. FIG. 2A is before polishing, and FIG. 2B is after polishing. The workpiece 101 installed in the through hole of the processing carrier 102 is polished by the polishing pads 103a and 103b, but the polishing pad is not corrected.

According to an aspect of the present invention, there is provided a planar polishing method for polishing both surfaces of an object to be processed in a through-hole of a processing carrier to a target thickness using a polishing pad. A flat polishing method is provided in which a correction plate having a thickness of .8 times or more and 1.0 times or less is provided, and the polishing pad has a hardness of 70 or more.
Fixed plate for use in the present invention, Ri shape der capable surface polishing, brass, SUS, epoxy impregnated glass, iron, copper, aluminum, comprises one or more selected from the group consisting of nickel and carbon becomes, covered with this material It may be what was done. Further, as described above, a correction carrier with diamond pellets, a SUS correction plate, or a glass correction plate may be used.
Although the thickness of a correction plate is not specifically limited, 0.1-300 mm is preferable according to the thickness of a to-be-processed object. The thickness of the correction plate is preferably 0.8 to 1 times the target thickness of the workpiece.

A state like of the present invention, for polishing a plurality of the article to be treated at the same time, if the processing carrier has a plurality of through holes, can improve Uebinesu by simultaneously deploying calibration plate in a part of the through hole .
The correction plate is not limited to the number or the like as long as it can be arranged between the polishing pad and the processing carrier in a well-balanced manner, and may be any shape such as a disk or a polygon.
3 and 4 are conceptual diagrams showing specific examples of the second aspect of the present invention.
FIG. 3 shows that the workpiece and the correction plate are separately installed on the processing carrier, and FIG. 4 shows that the workpiece and the correction plate are installed on the same processing carrier. In FIG. 3, the workpiece 11 is installed on the processing carrier 12a, and the correction plate 14 is installed on the processing carrier 12b, and polishing is performed using the polishing pad 13 (only one is shown). In FIG. 4, the workpiece 21 and the correction plate 24 are installed on the processing carrier 22, and polishing is performed using a polishing pad 23 (only one is shown). As shown in FIGS. 3 and 4, when a plurality of objects to be processed are used, they are preferably arranged in the circumferential direction on the processing carrier, and may have multiple turns. However, when a plurality of correction plates are used, it is desirable to arrange them so as to be symmetrical in the radial direction.

A state like the invention, calibration plate is polished and well contacts, alleviate irregularities of the polishing pad at the same time, stability of the polishing pad and the processing carrier, and the dimensional stability of the processing carrier in the polishing of the object And can further improve the business. Note that the thickness of the correction plate and the processing carrier may be the same, and the surface state of the polishing pad may be corrected by both the correction plate and the processing carrier, or the thickness of the processing carrier is made thinner than the correction plate and the correction plate Only the surface state of the polishing pad may be corrected. When thicker than modifying the thickness of the work carrier plate, it becomes possible to modify the surface condition of the polishing pad alone by processing the carrier, it will be included in state-like substantially present invention.

The processing carrier or correction plate used in the present invention is preferably one or more selected from the group consisting of diamond particles, alumina particles, titanium oxide particles, silicon carbide particles, titanium carbide particles and silica particles on the surface facing the polishing pad. Have The particles preferably have an average particle size of 150 μm or less.
For example, the processed carrier in the reference embodiment, the processed carrier in the embodiment of the present invention , and / or the correction plate is polished by forming particles of diamond, alumina, titanium oxide, silicon carbide, titanium carbide, or silica on the surface thereof. In addition, the polishing pad can be repaired at the same time, so that the effect of efficient polishing can be obtained. However, since the polishing pad is always carved during polishing, the consumption of the polishing pad is accelerated, so the average particle size is preferably 150 μm or less, more preferably 1 to 150 μm.

The hardness of the polishing pad is also important for improving the webiness. With a soft pad having a hardness of less than 70, even if the processing carrier of the present invention is used, the effect does not appear. The hardness was measured with a C-type hardness meter manufactured by Asker in accordance with JIS K7028.
According to the present invention, improvement in webiness can be realized by combining a processing carrier having a thickness of 0.8 times or more and 1.0 times or less of a target thickness of an object to be processed with a polishing pad having a hardness of 70 or more.
The polishing pad is preferably selected from the group consisting of non-woven fabric, suede, and polyurethane.

  The abrasive used in the present invention is not particularly limited, and is selected from such materials as silica, ceria, alumina, zirconia, diamond, and titanium oxide that are usually used in polishing.

Reference example 1
Twenty-five 2.5 inch glass (thickness 0.53 mm) substrates were prepared as objects to be processed. The lapping machine was a 9B double-side polishing machine (carrier size 9 inches), and a non-woven polishing pad (hardness 80) was prepared on the upper and lower plates. Full correction was made with a correction plate with diamond pellets. As the processing carrier, a SUS thickness of 0.50 mm (1.00 times the target thickness) was used. A total of five processing carriers were used, and five glass substrates were polished per one.
The abrasive was double-side polished using colloidal silica (manufactured by Fujimi) as a 10% slurry, and polished to a target thickness of 0.5 mm.
After polishing, the glass substrate was measured for webiness using Zygo (New View 5022).
The diamond particle size of the modified plate with diamond pellets was # 400.

Comparative Example 1
As a comparison with Reference Example 1, the polishing pad and the abrasive used are the same, the processing carrier is double-side polished using a thickness of 0.35 mm (0.7 times the target thickness) made by Galapoe, and the target thickness is 0.5 mm. The same measurement as in the reference example was performed.

Example 2
The polishing pad and the abrasive used in Reference Example 1 are the same, 15 2.5 inch glass (thickness 0.53 mm) substrates are used, and the processing carrier is 0.35 mm thick made by Galapoe (0.7 times the target thickness). three with use, (see Figure 4) were prepared a SUS fix two plates (1.00 times the thickness 0.5mm target thickness). performs double-side polishing, and polished to a target 0.5mm thickness, reference example Measurements similar to 1 were performed.

Reference Examples 3 to 5 and Comparative Example 2
40 test pieces of 2-inch aluminum (thickness 1.10 mm) substrates were prepared as objects to be processed.
The polishing material was the same as in Reference Example 1, and polishing pads with polyurethane hardness of 60 (Comparative Example 2), 70, 80, and 90 were prepared.
Five processing carriers made of brass having a thickness of 0.90 mm (0.9 times the target thickness) were prepared. Then, double-side polishing was performed, and the target was polished to a thickness of 1.00 mm.
After polishing, the aluminum substrate was measured for webiness using Zygo (New View 5022).

Example 6
30 substrates of 50 mm square glass (thickness 0.6 mm) were prepared as objects to be processed, and 0.70 times the target thickness made by ordinary glass epoxy was prepared as a processing carrier. In addition, ten SUS plate square glasses having a thickness of 1.00 times the target thickness of the object to be processed were prepared.
The polishing pad was made of polyurethane (hardness 80), and the abrasive was the same as in Reference Example 1. For one processed carrier, six workpieces and two SUS plates were used, and five processed carriers were used as 30 glass substrates and 10 SUS plates (see FIG. 4). Double-side polishing was performed to the target thickness, and after polishing, the glass substrate was measured for webiness using Zygo (New View 5022).

Example 7
Eighty 1 inch Si (0.4 mm thick) substrates were prepared as objects to be processed. Polishing was performed under the same conditions as in Example 2, and the webiness was measured.

<Webiness measurement>
Using Zygo (New View 5022), measurement was performed in a 3 × 2 mm visual field of the polished surface of the object to be processed after polishing. Since the measured value of this time may fluctuate up and down depending on the measurement range, measurement condition, and band pass of the measurement value, the measurement range and measurement condition are fixed, and the bandpass and the like are not filtered. Furthermore, in order to make the effects of the present invention easy to understand, Comparative Example 1 was represented as 1 and represented as a proportional value.

The results are shown in Table 1.
In Reference Example 1 and Comparative Example 1, clearly, the webiness value was smaller when a processing carrier having a target thickness of 1.00 times was used.
Also in Example 2, the thickness of the processing carrier or the correction plate was 1.00 times the target thickness, so that the webiness was improved as compared with Comparative Example 1. As in Example 2, even if the processing carrier is made of ordinary glass epoxy (0.70 times the target thickness), by using the SUS plate for correction (100 times the target thickness) at the same time, Improvement was observed.
From Reference Examples 3 to 5 and Comparative Example 2, the thickness of the processing carrier was set to 0.9 times the target thickness and the hardness of the polishing pad was changed. As a result, the webiness improved as the pad hardness increased. On the contrary, even when the thickness of the processing carrier is 0.9 times the target thickness, if the hardness of the polishing pad of Comparative Example 2 is 60 or less, the webiness is worse than that of Comparative Example 1. It is considered that the hardness of the polishing pad is preferably 70 or more. Therefore, it is considered preferable that the processing carrier thickness is 0.8 times or more and 1.00 times or less and the hardness of the polishing pad is 70 or more.
From Example 6, improvement of the webiness was recognized by arranging a plate having a target thickness of 0.8 or more on a normal glass-epoxy processing carrier.
In Example 7, a Si substrate was used as an object to be processed, but a marked improvement in webiness was recognized.

It is a conceptual diagram which shows the specific example of a reference aspect, (A) is before grinding | polishing and (B) is after grinding | polishing. It is a conceptual diagram which shows the conventional aspect, (A) is before grinding | polishing and (B) is after grinding | polishing. It is a conceptual diagram showing a specific example of a state like the present invention. It is a conceptual diagram showing a specific example of a state like the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing object 2 Processing carrier 3a Polishing pad 3b Polishing pad 101 Processing object 102 Processing carrier 103a Polishing pad 103b Polishing pad 11 Processing object 12a Processing carrier 12b Processing carrier 13 Polishing pad 14 Correction plate 21 Processing object 22 Processing carrier 23 Polishing pad 24 Correction plate

Claims (6)

A planar polishing method for polishing both surfaces of an object to be processed disposed in a through hole of a processing carrier to a target thickness using a polishing pad, wherein the target thickness is 0.8 in the through hole of the processing carrier. A flat polishing method characterized in that a correction plate having a thickness of not less than twice and not more than 1.0 times is disposed, and the polishing pad has a hardness of 70 or more ,
A surface polishing method, wherein the correction plate comprises one or more selected from the group consisting of brass, SUS, epoxy-impregnated glass, iron, copper, aluminum, nickel, and carbon .   The object to be treated is glass, B, C or Si, or a single metal selected from the group consisting of Fe, Cr, Ni, Cu, Co, Al, Sn, Mo, W, Ta, Ti and Nb, or two or more kinds The surface polishing method according to claim 1, comprising an alloy of: The calibration plate is, on a surface opposed to the polishing pad, diamond particles, alumina particles, titanium oxide particles, according to claim 1 or claim 2 having one or more selected from the group consisting of silicon carbide particles and the titanium carbide particles Surface polishing processing method. The surface polishing method according to claim 3 , wherein particles on the surface of the correction plate have an average particle size of 150 μm or less. The calibration plate is, surface grinding method according to any one of claims 1 to 4, which is a disc or polygon. The object to be processed, a substrate for a liquid crystal display, a substrate for a magnetic recording medium, a photomask substrate, planar polishing method according to any one of claims 1 to 5 selected from the group consisting of a substrate for device .

Images