JP2008155323A - Wet polishing method and wet polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wet polishing method which shortens through-put by using a conventional polishing device as it is, or by slight remodeling, and also to provide a wet polishing device for carrying out this method. <P>SOLUTION: The method applies the wet polishing device provided with a polishing section (10) for polishing a workpiece (S) by holding it between an upper polishing plate and a lower polishing plate arranged so as to be opposed to each other in the vertical direction while supplying polishing fluid, and workpiece developing stages (41) (71) arranged in at least one of the front and the rear stage of the polishing section (10), having mounting trays (45) (75) for mounting the workpiece (S) in recessed portions formed in their upper surfaces. It stores an etchant (W) in the recessed portions of the mounting trays (45) (75), and while it polishes the workpiece (S) by the polishing section (10), it makes another workpiece on stand-to in a state of it being immersed in the etchant (W) in the workpiece developing stages (41) (71), and performs etching. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wet polishing method for performing etching with an etchant and polishing with a polishing liquid, and a wet polishing apparatus for performing the polishing method.

  In the polishing of Ni-P plated aluminum substrate for magnetic disk, which requires high precision surface finish, the process is divided into a plurality of times, and in rough polishing, alumina having a particle size of about 0.5 to 1.7 μm is used as an acidic dispersion medium. In the final polishing, so-called chemical etching and mechanical polishing are performed using a polishing liquid in which colloidal silica having a particle size of about 7 to 50 nm is suspended in the same acidic dispersion medium. Combined wet polishing is performed.

  Today, this process is generally performed by an automatic polisher. Polishing capacity per unit time, so-called throughput, is limited by the time spent on polishing, and how to shorten the polishing time is productivity It has become a point to raise. In order to finish with high accuracy in a short time, the combination of various conditions such as the type and properties of the abrasive and polishing cloth used, and the processing pressure and rotation speed of the polishing machine are being studied. Each has a trade-off relationship, and it is difficult to find innovative breakthroughs.

When analyzing the time required for processing, it is spent in the initial stage to remove the natural oxide film on the surface of the workpiece, and then it is spent to polish the substrate metal film (Ni-P plating) to a flat and mirror surface. It has been done. In general, a natural oxide film has a property that it is harder to polish than a metal film, but an abrasive is often optimized for wet polishing of a metal film (Ni-P plating). For this reason, a method has been devised in which the natural oxide film is removed by dissolution with a chemical solution or dry etching with gas before polishing (see Patent Document 1).
JP 2005-277396 A

  However, in the method described in Patent Document 1, it is necessary to newly provide an etching apparatus for performing a natural oxide film removal step before the polishing process or to provide a mechanism for changing the polishing pressure. For this reason, in order to carry out this method, it is inevitable to modify the conventional polishing apparatus, and it is a large-scale modification. Further, as shown in FIG. 2 of Patent Document 1, since the chemical solution for etching is sprayed on the substrate, the processing efficiency is poor, and the throughput for obtaining a predetermined finished surface roughness is hardly shortened.

  In view of the above-described technical background, an object of the present invention is to provide a wet polishing method capable of reducing the throughput as it is with a conventional polishing apparatus as it is or with a slight modification, and a wet polishing apparatus for performing this polishing method.

  That is, the wet polishing method of the present invention has the configurations described in [1] to [5] below.

[1] A polishing unit that sandwiches a workpiece between an upper surface plate and a lower surface plate that are vertically opposed to each other and polishes while supplying a polishing liquid, and is disposed in at least one of a front stage and a rear stage of the polishing unit. And using a wet polishing apparatus provided with a workpiece development stage having a placement tray for placing the workpiece in a recessed portion formed on the upper surface,
The etchant is stored in the recessed portion of the placing tray, and while the workpiece is polished by the polishing unit, the workpiece is developed while waiting for another workpiece to be immersed in the etchant at the workpiece development stage. A wet polishing method characterized by the above.

  [2] The workpiece developing stage is a loading stage that is arranged in front of the polishing unit and waits for the workpiece to be loaded in the polishing unit. The workpiece is polished after being immersed in an etchant and etched. 2. The wet polishing method according to item 1.

  [3] The workpiece development stage is a discharge stage that is arranged at the rear stage of the polishing unit and waits for the polished workpiece to be discharged from the wet polishing apparatus, and is used as an etchant after polishing the workpiece. 3. The wet polishing method according to 1 or 2 above, wherein immersion is performed and etching is performed.

  [4] The wet polishing method according to any one of items 1 to 3, wherein the workpiece is an aluminum magnetic disk substrate.

  [5] The wet polishing method according to any one of items 1 to 4, wherein any one of a dispersion medium of the polishing liquid, a concentrated liquid of the dispersion medium, and a dilution liquid of the dispersion medium is used as the etchant.

  Moreover, the wet polishing apparatus of the present invention has a configuration described in [6] to [12] below.

[6] A polishing unit that sandwiches a workpiece between an upper surface plate and a lower surface plate that are vertically opposed to each other and polishes while supplying a polishing liquid, and is disposed in at least one of a front stage and a rear stage of the polishing unit. A wet polishing apparatus comprising a workpiece development stage having a mounting tray on which the workpiece is placed and stands by,
A wet tray characterized in that a mounting tray of the workpiece development stage has a recessed portion for storing an etchant on an upper surface, and the workpiece is placed and etched while being immersed in the etchant. Polishing equipment.

  [7] The wet polishing apparatus according to [6], wherein the workpiece unfolding stage is a loading stage that is arranged in a front stage of the polishing unit and waits for a workpiece to be loaded in the polishing unit.

  [8] The wet polishing apparatus according to [6] or [7], wherein the workpiece development stage is a discharge stage that is disposed at a subsequent stage of the polishing unit and waits for a polished workpiece discharged from the wet polishing apparatus. .

  [9] As the placement transfer unit, transfer that holds the workpiece by the workpiece development stage and the holding unit, and transfers the workpiece between the polishing unit and the workpiece development stage. 9. The wet polishing apparatus according to any one of the preceding items 6 to 8, comprising an apparatus.

[10] The polishing unit includes a carrier in which a holding hole for loading a workpiece is formed, and the placement transfer unit includes the same number of mounting trays and gripping units as the holding hole of the carrier. The wet polishing apparatus according to 9 above, wherein the workpieces are collectively transferred. [11] The workpiece development stage has the same number of plates as the carrier of the polishing unit, and each plate has a holding hole of each carrier. 11. The wet polishing apparatus according to the above item 10, having the same number of mounting trays.

  [12] In the preceding paragraph 11, a recess is formed by fitting a ring-shaped mounting tray into a bottomed recess formed in the plate, and a groove is provided in the bottom of the recess so as to communicate the recess. The wet polishing apparatus as described.

  According to the wet polishing method described in [1] above, before or after the workpiece is polished by the polishing section, the workpiece is immersed in an etchant in the mounting tray of the workpiece development stage and etched. The polishing time for obtaining the finished surface roughness can be shortened. In addition, since the etching is performed on the magnetic disk substrate waiting before and after the polishing portion, the throughput is not extended due to the etching. Accordingly, the throughput is shortened by shortening the polishing time.

  According to the wet polishing method described in [2] above, the oxide film on the surface is first removed by etching, and then the polishing is performed at the polishing portion, which is particularly effective for shortening the polishing time.

  According to the wet polishing method described in [3] above, etching is performed as a finishing treatment after polishing, which is particularly effective in improving surface smoothness.

  The wet polishing method according to the above [4] performs both etching and polishing, and is suitable for polishing a workpiece that requires a high level of polishing quality. Therefore, it is suitable for polishing an aluminum magnetic disk substrate.

  According to the wet polishing method described in [5], the influence when the etchant is brought into the polishing liquid is extremely small.

  The wet polishing apparatus according to [6] can be used for carrying out the wet polishing method according to [1] to [5].

  The wet polishing apparatus according to [7] can be used particularly for carrying out the wet polishing method according to [2].

  The wet polishing apparatus described in the above [8] can be used particularly for carrying out the wet polishing method described in the above [3].

  According to the wet polishing apparatus described in [9] above, when the wet polishing method described in [1] to [5] is performed, the workpiece can be transferred smoothly.

  According to the wet polishing apparatus described in [10], a plurality of workpieces can be efficiently transferred when the wet polishing method described in [1] to [5] is performed.

  According to the wet polishing apparatus described in [11] above, when the wet polishing method described in [1] to [5] is performed, the region immersed in the etchant is partitioned, so that the apparatus and maintenance can be simplified. .

  According to the wet polishing apparatus described in [12] above, it is easy to adjust the water level of the plurality of mounting trays on the plate when performing the wet polishing method described in [1] to [5] above.

  1 to 6 illustrate a wet polishing apparatus (1) for carrying out the wet polishing method of the present invention. The wet polishing apparatus (1) includes a loader unit (40), a polishing unit (10), an unloader unit (70), and further includes a supply unit (60), a cleaning and drying unit (61), and a discharge unit (62). It has. The loader section (40) and the unloader section (70) correspond to the placement / transfer section in the present invention.

  The wet polishing apparatus (1) is an apparatus used for polishing a magnetic disk substrate (S) on a disk having a through hole (S1), and is stored in a cassette case (C) and transported. The magnetic disk substrate (S) is polished, washed, and dried in order, and the operations from the storage to the cassette case (C) and the discharge are continuously performed.

  In the wet polishing apparatus (1), the polishing unit (10) simultaneously polishes a predetermined plurality of magnetic disk substrates (S), and transfers the magnetic disk substrate (S) to the polishing unit (10) and the polishing unit ( The transfer from 10) may be performed in batches in units of the number of polished sheets. Therefore, in the loader unit (40), the magnetic disk substrate (S) is transferred from the cassette case (C) conveyed from the supply unit (60). ) Are taken out one by one, and a predetermined number of sheets are developed and placed in a polishing posture. Similarly, the polished magnetic disk substrate (S) is collectively transferred from the polishing unit (10) to the unloader unit (70) in the polishing posture, and washed one by one from the unloader unit (70). It is transferred to the drying section (61). A predetermined number of magnetic disk substrates (S) that have been washed and dried are stored in the cassette case (C), and discharged from the discharge section (62) to the outside of the apparatus.

The detailed configuration and operation of each part will be described in detail below.
[Polishing part]
As shown in FIGS. 2 and 3, the polishing section (10) is composed of a lower surface plate (11), an upper surface plate (15), a sun gear (20), an internal gear (22), a carrier (30), and the like. A configured planetary gear type polishing unit may be employed, for example.

  The lower surface plate (11) is a disk member having an annular horizontal upper surface, and a polishing cloth (12a) is attached to the upper surface. The lower surface of the lower surface plate (11) is fixed to a lower support member (13) rotatable about a vertical axis (Q), and the lower support member (13) is linked to the lower surface plate rotation drive unit (14). The lower surface plate (11) and the lower support member (13) are configured to rotate.

  The upper surface plate (15) is also a disk member having an annular horizontal lower surface, and a polishing cloth (12b) is bonded to the lower surface facing the lower surface plate (11). The upper surface of the upper surface plate (15) is fixed to an upper support member (16) that is rotatable about a vertical axis (Q), and the upper support member (16) is attached to the upper surface plate rotation drive unit (17). The upper surface plate (15) and the upper support member (16) are rotated in association with each other. The upper surface plate (15) and the upper support member (16) are supported so as to be movable up and down along the vertical axis (Q) and are moved up and down by driving an upper surface plate lifting and lowering drive unit (not shown). ing. The upper surface plate (15) is provided with a number of polishing liquid supply holes (18) and peeling fluid supply holes (19) penetrating the polishing pad (12b).

  The sun gear (20) is rotatably provided at the center position of the polishing section (10), and is rotated about the vertical axis (Q) by driving the sun gear rotation driving section (21). Yes. However, when rotating the internal gear (22), the sun gear (20) may be fixed so as not to rotate. As the sun gear (20), a spur gear, a pin gear, or the like in which a tooth row is integrally formed on a side surface portion is used.

  The internal gear (22) is a ring-shaped gear having a tooth row on the inner peripheral side, and is arranged concentrically on the outer side of the sun gear (20). The internal gear (22) of the present embodiment is fixed so as not to rotate, but an internal gear rotation drive unit may be additionally installed to be rotatable about the vertical axis (Q). Also, in the internal gear (22), a pin gear or the like may be used in addition to the spur gear.

  The carrier (30) is a thin plate-like disk member having a tooth row on the outer periphery, and a plurality of holding holes (31) for loading and holding the workpiece (S) are formed. In the polishing section (10), a plurality of carriers (30) are arranged. These carriers (30) mesh with the sun gear (20) and the internal gear (22), and the sun gear (20) and / or According to the rotation of the internal gear (22), it rotates while revolving around the sun gear (20).

  In the polishing section (10), the workpiece (S) held by the carrier (30) is sandwiched between the upper surface plate (15) and the lower surface plate (11), and the carrier (30) is rotated and rotated in this state. By doing so, the upper and lower surfaces of the workpiece (S) are polished. In this polishing section (10), a donut-shaped region sandwiched between the sun gear (20) and the internal gear (22) and between the upper surface plate (15) and the lower surface plate (11) is actually polished. It becomes an area.

  A polishing liquid supply device (34) is provided above the upper surface plate (15). The polishing liquid supply device (34) includes a bowl-shaped main body (35), nozzles (36) and (37) for introducing the polishing liquid and the rinse liquid into the bowl-shaped main body (35), and a tank for storing the polishing liquid and the rinse liquid. (Not shown), a tube (not shown) for connecting these tanks and the nozzles (36), (37) in communication, and a tank-shaped body (35) connected to supply the polishing liquid to the polishing section (10). A tube (38) is provided. The tube (38) is connected in communication with the polishing liquid supply hole (18) of the upper surface plate (15). Reference numeral (39) denotes a tube for introducing a peeling fluid for peeling the workpiece (S) stuck to the upper surface plate (15).

  In the present embodiment, the number of carriers (30) is eight, and each carrier (30) has five holding holes (31).

[Loader section]
For example, as shown in FIG. 2, the loader section (40) is arranged in front of the polishing section (10), and a circular table (41) rotatably installed on a table (not shown) and the table ( 41) and a transfer device (50) disposed above. The table (41) corresponds to the workpiece development stage in the present invention.

  On the table (41), the same number of plates (42) as the carrier (30) of the polishing section (10) are attached in the same arrangement as the carrier (30). As shown in FIGS. 4 and 6, each plate (42) has a bottomed circular recess (43) at a position corresponding to the holding hole (31) of the carrier (30), and a groove provided at the bottom. (44) communicate with each other. Then, by fitting the ring-shaped resin mounting tray (45) into the recesses (43) flush with each other, a bottomed recess is formed, and the etchant (W) is stored. The inner peripheral portion of the mounting tray (45) is rolled into a concave shape to form a step portion (45a), and this ring-shaped step portion (45a) supports the outer edge of the lower surface of the magnetic disk substrate (S). The Further, a bank (46) for damming the etchant (W) is provided at the periphery of the upper surface of the plate (42). Then, when the etchant (W) is supplied onto the plate (42) from the liquid supply pipe (47) provided radially from the center of the table (41), it flows into the mounting tray (45) and flows into the groove (44). And is supplied to all the loading trays (45) through the water level. In this way, the water level of the plurality of loading trays (45) can be easily adjusted by communicating the recesses (43). The discharge of the etchant (W) in the placing tray (45) can be appropriately performed by overflowing from the plate (42) or by providing a drain outlet at the bottom of the table groove (44).

  As shown in FIGS. 2 and 5, the transfer device (50) moves the movable substrate (51) horizontally between the table (41) and the lower surface plate (11) of the polishing unit (10). The movable substrate (51) can be moved up and down, and the same number of gripping units (52) as the plate (42) are attached to corresponding positions of the plate (42) on the lower surface of the movable substrate (51). The gripping unit (52) attaches the same number of gripping portions (54) as the mounting tray (45) in the plate (42) to a circular mounting plate (53), and attaches the mounting plate (53) to a mounting shaft (55). ) Attached to the movable substrate (51). Each gripping portion (54) has a pair of resin-made claws (56) (56) that can be opened and closed by air supply and discharge, etc., and the through-holes of the magnetic disk substrate (S) are formed on the outer surfaces of these claws (56). A groove (57) for gripping the peripheral end face of (S1) is formed (see FIG. 6). The attachment position of each gripping part (54) corresponds to the mounting tray (45) on the plate (42).

[Unloader section]
The unloader unit (70) is disposed at the rear stage of the polishing unit (10), and is disposed above the table (71) and a circular table (71) rotatably installed on a table (not shown). And a transfer device (80). The table (71) corresponds to the workpiece development stage in the present invention.

  The table (71) and the transfer device (80) have the same configuration as the table (41) and the transfer device (50) of the loader unit (40) except that the respective parts are arranged symmetrically. The description of the same name is omitted because it has the same function, and only the symbol is changed to distinguish it from the loader (40). That is, (72) is a plate, (73) is a recess, (74) is a groove, (75) is a loading tray, (75a) is a step, (76) is a bank, and (77) is a supply pipe. . (81) is a movable substrate, (82) is a gripping unit, (83) is a circular mounting plate, (84) is a gripping part, (85) is a mounting shaft, (86) (86) is a pair of claws, (87) is a groove.

  In the above-described wet polishing apparatus (1), the polishing liquid used in the polishing section (10) and the etchant stored in the mounting trays (45) and (75) are not limited, and the material to be processed, the required surface roughness, etc. What is necessary is just to select suitably according to.

  Examples of the polishing liquid include a suspension obtained by dispersing colloidal silica or alumina in a dispersion medium such as water or acid. Accordingly, mechanical polishing or chemical mechanical polishing is performed in the polishing section (10). As an etchant, an inorganic acid or an organic acid such as oxalic acid or citric acid is used alone or a mixture of two or more thereof is appropriately diluted with a solvent such as water to adjust the pH to about 1.3 to 2.8. It can be illustrated. Further, as the etchant, the dispersion medium of the polishing liquid used in the polishing section (10) can be used as it is, or a concentrated liquid or dilution liquid of this dispersion medium can be used. If a dispersion medium of the polishing liquid is used, even if the etchant is brought into the polishing liquid when the magnetic disk substrate (S) is transferred, only the abrasive concentration is diluted. Therefore, there is an influence of contamination of the polishing liquid. No or very little. The etchant of the loader unit (40) and the unloader unit (70) may be the same or different.

〔Working process〕
In the above-described wet polishing apparatus (1), while the magnetic disk substrate (S) is transferred through each part, polishing, cleaning and drying are successively performed in the following order (i) to (ix).

  As preparation for continuous processing, the etchant (W) is supplied from the liquid supply pipe (47) of the loader section (40) and the liquid supply pipe (77) of the unloader section (70), and the mounting tray (45) (75) Store in.

  (I) The cassette case (C) is conveyed to the side of the table (41) of the loader section (40) by the conveyor of the supply section (60).

  (Ii) The magnetic disk substrates (S) in the cassette case (C) are taken out one by one, transferred to the table (41), and placed on the placement tray (45) so that the polishing surface is horizontal. The above transfer operation is performed while appropriately rotating the table (41), and the magnetic disk substrates (S) are developed and mounted on all the mounting trays (45). Since the etchant (W) is stored in the mounting tray (45), the magnetic disk substrate (S) is immersed in the liquid (see FIG. 6). Etching is performed while the magnetic disk substrate (S) is immersed in the etchant (W), and the metal oxide film on the surface is removed.

  (Iii) The transfer device (50) of the loader unit (40) is moved directly above the table (41), and then the movable substrate (51) is lowered. The claws (56) (56) of each gripping part (54) are opened after being inserted into the through hole (S1) of the magnetic disk substrate (S), and the peripheral end surface of the through hole (S1) is gripped by the groove (57) ( (See FIG. 6). Since the gripping portion (54) is provided corresponding to all the mounting trays (45), all the magnetic disk substrates (S) are gripped simultaneously.

  (Iv) The movable substrate (51) is raised and moved directly above the lower surface plate (11) of the polishing section (10). Subsequently, the movable substrate (51) is lowered, and the magnetic disk substrate (S) is loaded into the holding hole (31) of the carrier (30). Then, after closing the claws (56) and (56) of the gripping part (54), the movable substrate (51) is lifted and horizontally moved back to the loader part (40). As a result, a predetermined number of magnetic disk substrates (S) are collectively transferred from the loader unit (40) to the polishing unit (10).

  (V) In the polishing section (10), the upper surface plate (15) is lowered to sandwich the magnetic disk substrate (S) loaded in the carrier (30), and the polishing liquid is supplied from the polishing liquid supply device (34). At the same time, both surfaces of the magnetic disk substrate (S) are polished. After polishing, the upper surface plate (15) is raised.

  (Vi) The movable substrate (81) of the transfer device (80) of the unloader section (70) is moved immediately above the lower surface plate (11) and then lowered. The claws (86) and (86) of each gripping part (84) are opened after being inserted into the through hole (S1) of the magnetic disk substrate (S), and the peripheral end face of the through hole (S1) is gripped by the groove (87). Since the holding portion (84) is provided corresponding to all the magnetic disk substrates (S), all the magnetic disk substrates (S) are simultaneously held.

  (Vii) The movable substrate (81) is raised and moved directly above the table (71) of the unloader section (70), and then the movable substrate (81) is lowered. When the magnetic disk substrate (S) is placed on the placement tray (75), the claws (86) and (86) of the grip portion (84) are closed to release the grip, and the movable substrate (81) is raised. As a result, a predetermined number of magnetic disk substrates (S) are collectively transferred from the polishing section (10) to the unloader section (70), and the polished magnetic disk substrates (S) are immersed in the etchant (W). Then, etching is performed.

  (Viii) The magnetic disk substrates (S) placed on the unloader unit (70) are transferred one by one to the cleaning / drying unit (61) to perform cleaning and drying. The dried magnetic disk substrate (S) is transferred, stored in the cassette case (C), and discharged out of the apparatus by the discharge conveyor of the discharge section (62).

  (Ix) The cycle of (i) to (viii) is repeated.

  In the above cycle, after the step (iv), the loading tray (45) of the loader unit (40) is emptied, the polishing in the polishing unit (10) is finished, and the holding hole (31) of the carrier (30) is opened. The loader unit (40) is in a standby state until it becomes empty. During this standby, the step (ii) is carried out, and the magnetic disk substrate (S) of the next cycle is transferred to the loader unit (40) and placed on the placement tray (45), and the etchant (W) is placed. Immerse and etch. In other words, the loading tray (45) of the loader unit (40) has a waiting time until the holding hole (31) of the carrier (30) of the polishing unit (10) is empty. Etching is performed. Since the oxide film on the surface is removed by this etching, the polishing time for obtaining a predetermined finished surface roughness can be shortened in the polishing portion (10). As a result, the throughput for obtaining a predetermined finished surface roughness can be shortened.

  In order to make the etching time, ie, the immersion time shorter than the waiting time, the timing for transferring the magnetic disk substrate (S) from the cassette case (C) to the loader unit (40) may be delayed. On the other hand, even when the time required for etching is longer than the waiting time, the above-described effects can be achieved by immersion within the waiting time. Of course, in order to lengthen the etching time, the transfer from the loader section (40) to the polishing section (10) can be delayed, or the etchant side conditions such as composition and temperature can be changed to shorten the etching time. It can also be done arbitrarily. Even when the transfer from the loader unit (40) to the polishing unit (10) is delayed in obtaining the desired surface roughness, the effects of the present invention can be achieved if the throughput can be shortened by combining etching and polishing. it can.

  Also, in the unloader unit (70), if the polishing of the next cycle is not completed, the magnetic disk substrate (S) is not transferred from the polishing unit (10), and this time is a waiting time. If there is no magnetic disk substrate (S) transferred from the polishing unit (10), even if it is quickly transferred to the cleaning / drying unit (61), the polishing becomes the rate-determining step and the throughput is not shortened. Etching can be performed using By this etching, the finishing process of the magnetic disk substrate (S) polished by the polishing section (10) is performed, and the surface smoothness can be improved. Alternatively, the polishing time necessary to obtain a predetermined finished surface roughness can be shortened.

  Further, in the wet polishing apparatus described above, the gripping parts (54) and (84) of the transfer apparatuses (50) and (80) in the loader part (40) and the unloader part (70) are mounted on the mounting trays (45) and (75). When the magnetic disk substrate (S) is held, the claws (56) (86) are immersed in the etchant (W). For this reason, it is possible to prevent the polishing liquid adhering at the polishing section (10) from being washed with the etchant (W) and drying the polishing liquid into a hard lump and damaging the magnetic disk substrate (S).

  According to the wet polishing method and the wet polishing apparatus of the present invention, etching is performed using the waiting time until the workpiece is loaded in the polishing section, or the waiting time until the polished workpiece is advanced to the next process. And can reduce the throughput to obtain the desired surface roughness. A polishing method in which such etching and polishing are combined is suitable for polishing a workpiece that requires a high level of polishing quality. Examples of the workpiece include a magnetic disk substrate made of aluminum or an aluminum alloy plate, a glass substrate, or a magnetic disk substrate having a Ni-P plating film on the surface of the substrate.

  Further, the wet polishing apparatus can carry out the above-described wet polishing method only by providing a recess for storing an etchant on a tray on which a workpiece is placed. For this reason, if it is a polishing apparatus that develops a workpiece on the mounting tray and stands by, it is not necessary to newly install an etching apparatus, and it is easily performed only by changing the mounting tray and adding an etchant supply / discharge facility. be able to. Moreover, since the substantial process change is only shortening the polishing time, the control program is also slightly changed.

  The wet polishing apparatus of the present invention is not limited to the above embodiment.

  In the present invention, the workpiece development stage having the mounting tray for storing the etchant may be provided at least one of the front stage and the rear stage of the polishing unit. That is, it is only necessary to provide a mounting tray capable of storing an etchant in at least one of the preceding loading stage and the subsequent discharging stage, and the present invention includes a case where etching is performed with only one of them. Even with only one etching, a corresponding effect can be obtained and the throughput can be shortened. Further, etchants having different compositions can be used for the loading stage and the discharging stage.

  Moreover, the transfer means of the workpiece between the workpiece development stage and the polishing section is not limited.

  Further, the configuration of the polishing unit is not limited to the combination of the sun gear and the internal gear of the embodiment described above to rotate and revolve the carrier, and any sliding means can be incorporated. Further, the apparatus configuration other than the loading / unloading unit (loader unit and unloader unit in the above embodiment), a method for transferring the workpiece to the loading / unloading unit (loader unit), and the loading / unloading unit (unloader). The method of transferring from (part) to the next process is not limited.

  It is sufficient that there is at least one mounting tray for the workpiece development stage, and the case where the number of mounting trays does not match the total number of holding holes of the carrier is also included in the present invention. However, by providing the same number of mounting trays as the carrier holding holes, batch transfer is possible and work efficiency is improved. In this embodiment, the mounting trays are grouped using plates corresponding to the carriers, but the present invention is not limited to grouping using plates. By grouping the mounting trays, an area immersed in the etchant is partitioned, and the apparatus can be simplified and maintenance can be performed more easily than supply for each mounting tray or batch supply to all mounting trays. In addition, a configuration in which the mounting tray and the plate are integrated and a configuration in which the mounting tray on the plate is independent without being communicated are also included in the present invention. Further, the method of supplying the etchant is not limited at all.

  A polishing test of the workpiece (S) was performed using the wet polishing apparatus (1) which is an example of the present invention shown in FIGS.

  As a test workpiece (S), an aluminum plate having a diameter of 95 mm having Ni-P plating films on both sides was used. This aluminum plated plate is used as a magnetic disk substrate. The polishing liquid used was a dispersion of colloidal silica in pure water, and pure water was used as the rinse liquid.

  As an example of the present invention, the etchant (W) was stored in the mounting trays (45) and (75) of the loader unit (40) and the unloader unit (70), and etching was performed before and after polishing. The etchant used in the loader unit (40) is a nitric acid-based etchant solution, and the etchant used in the unloader unit (70) is a HEDP (hydroxyethane diphosphonic acid) -based etchant solution.

  On the other hand, as a comparative example, the loader unit (40) of the wet polishing apparatus (1) and the loading trays (45) and (75) of the unloader unit (70) do not store the etchant, and the loader unit (40) and Magnetic disk substrate (S) until unloader unit (70) is simply transferred to a stage for loading magnetic disk substrate (S) to be loaded into polishing unit (10) or to cleaning and drying unit (61) It was used as a discharge stage that kept waiting.

  Then, 40 workpieces (8 carriers, 5 holding holes) are processed as one unit, transfer from the loader unit (40) to the polishing unit (10), and from the polishing unit (10). The transfer to the unloader part (70) was performed in batches for each unit, and further washed and dried. This transfer from polishing to washing and drying was repeated as one cycle, and both surfaces of 10,000 aluminum plated plates were polished for each condition.

  In this polishing cycle, the magnetic disk substrate (S) in the embodiment is etched by the loader unit (40), polished by the polishing unit (10), and then also etched by the unloader unit (70). On the other hand, the magnetic disk substrate (S) in the comparative example is only polished by the polishing section (10) and is not processed at all by the loader section (40) and the unloader section (70).

[Test 1]
In the polishing cycle, the target finished surface roughness (Ra) was set to 0.6 nm. The polishing time and the polishing amount in the polishing section (10) were set so that this target surface roughness (Ra) was achieved. In the examples, the polishing time of the polishing portion (10) was set in consideration of etching performed before and after polishing. Table 1 shows the set polishing time and polishing amount.

  When the magnetic disk substrate (S) is transferred from the loader unit (40) to the polishing unit (10) and the loader unit (40) is in a standby state, the magnetic disk substrates (S) of the next cycle are sequentially loaded into the loader unit. It was transferred to the mounting tray (45) of (40) and waited in the mounting tray (45) until it could be transferred to the polishing section (10). Similarly, the unloader unit (70) is transferred to the unloader unit (70) immediately after the polishing in the polishing unit (10), and is placed until it can be transferred to the cleaning / drying unit (61). Waited in the tray (75). In this polishing cycle, the immersion time in the etchant in the loader part (40) and the unloader part (70) of the example was the time shown in Table 1. The immersion time is the immersion time of the magnetic disk substrate (S) last transferred from the cassette case (C) to the mounting tray (45) in the loader unit (10), and is the first in the unloader unit (70). The immersion time of the magnetic disk substrate (S) transferred from the mounting tray (75) to the cleaning / drying unit (61).

  In the above cycle, for each magnetic disk substrate (S), the processing time required from the start of transfer to the loader section (40) to the end of drying was determined and compared between the example and the comparative example.

[Test 2]
In the above polishing cycle, the target finished surface roughness (Ra) was set to 1 nm, and the polishing test was conducted in the same manner as in Test Example 1.

  These results are shown in Table 1.

  From the results in Table 1, it was found that the throughput can be shortened by about 5% by performing etching using the waiting time.

  In the example and the comparative example, the time required for transfer and transfer of the magnetic disk substrate (S) is equal, so the difference in processing time is the difference in polishing time in the polishing section (10). In other words, the etching time can be shortened by performing etching before and after the polishing, and the throughput is not extended because the etching is performed using the standby time.

  The wet polishing method of the present invention can efficiently perform high-quality polishing by combining etching and polishing. Therefore, it is suitable for polishing a magnetic disk substrate that requires high polishing quality.

It is a front view which shows schematic structure of one Embodiment of the wet polishing apparatus of this invention. FIG. 2 is a perspective view showing a loader unit, a polishing unit, and an unloader unit in the wet polishing apparatus of FIG. 1. It is principal part sectional drawing of a grinding | polishing part. It is a perspective view which shows the plate of a loader part and an unloader part. It is a perspective view which shows the principal part of the transfer apparatus of a loader part and an unloader part. It is principal part sectional drawing which shows a mounting tray and a holding part.

Explanation of symbols

1 ... Wet polishing equipment
10 ... Polishing part
11 ... Lower surface plate
15… Upper surface plate
30 ... Career
31 ... Holding hole
40… Loader section (mounting / transferring section)
41,71 ... Table (workpiece development stage)
42,72… Plate
43 ... recess
44 ... Groove
45,75 ... Loading tray
70 ... Unloader section (mounting / transferring section)
50,80 ... Transfer device
54,84… Holding part
56,86 ... Nail S ... Magnetic disk substrate (workpiece)
S1 ... through hole W ... etchant

Claims (12)

A polishing part that is sandwiched between an upper surface plate and a lower surface plate that are vertically opposed to each other and polished while supplying a polishing liquid, and is disposed on at least one of a front stage and a rear stage of the polishing part, and an upper surface Using a wet polishing apparatus provided with a workpiece development stage having a placement tray for placing the workpiece in a recessed portion formed in
The etchant is stored in the recessed portion of the placing tray, and while the workpiece is polished by the polishing unit, the workpiece is developed while waiting for another workpiece to be immersed in the etchant at the workpiece development stage. A wet polishing method characterized by the above.   2. The workpiece development stage is a loading stage that is arranged in front of the polishing unit and waits for a workpiece to be loaded in the polishing unit, and is polished after being immersed in an etchant and etched. The wet polishing method according to 1.   The workpiece development stage is a discharge stage that is disposed after the polishing unit and waits for a polished workpiece to be discharged from the wet polishing apparatus. After polishing the workpiece, the workpiece is immersed in an etchant and etched. The wet polishing method according to claim 1 or 2.   The wet polishing method according to claim 1, wherein the workpiece is an aluminum magnetic disk substrate.   The wet polishing method according to claim 1, wherein any one of a dispersion medium of the polishing liquid, a concentrated liquid of the dispersion medium, and a diluted liquid of the dispersion medium is used as the etchant. A workpiece is sandwiched between an upper surface plate and a lower surface plate that are vertically opposed to each other and polished while supplying a polishing liquid, and is disposed in at least one of a front stage and a rear stage of the polishing section, A wet polishing apparatus comprising a workpiece development stage having a placement tray for placing a workpiece on standby;
A wet tray characterized in that a mounting tray of the workpiece development stage has a recessed portion for storing an etchant on an upper surface, and the workpiece is placed and etched while being immersed in the etchant. Polishing equipment.   The wet polishing apparatus according to claim 6, wherein the workpiece developing stage is a loading stage that is disposed in a front stage of the polishing unit and waits for a workpiece to be loaded in the polishing unit.   8. The wet polishing apparatus according to claim 6, wherein the workpiece developing stage is a discharge stage that is disposed at a subsequent stage of the polishing unit and waits for a polished workpiece discharged from the wet polishing apparatus.   As the placement transfer unit, the workpiece development stage, and a transfer device that holds the workpiece by the gripping unit and transfers the workpiece between the polishing unit and the workpiece development stage. A wet polishing apparatus according to any one of claims 6 to 8.   The polishing unit has a carrier in which a holding hole for loading a workpiece is formed, and the placement and transfer unit has the same number of mounting trays and gripping portions as the holding hole of the carrier, and all the workpieces The wet polishing apparatus according to claim 9, wherein the transfer is performed in a lump.   The wet polishing apparatus according to claim 10, wherein the workpiece development stage has the same number of plates as the carrier of the polishing unit, and each plate has the same number of mounting trays as the holding holes of the carriers.   12. The recessed portion is formed by fitting a ring-shaped mounting tray into a recessed portion having a bottom formed on the plate, and a groove is provided in the bottom portion of the recessed portion to communicate the recessed portion. Wet polishing equipment.

Images