JPH01210259A - Polishing machine - Google Patents

Abstract

PURPOSE:To achieve very high polishing accuracy with high efficiency by forming a first groove for storing working liquid in the polishing face of a polishing board and forming a second groove shallower than the first groove at a position on the polishing face where the first groove is not formed. CONSTITUTION:First spiral groove 12 is etched concentrically to a polishing plate 8 on the upper face or the polishing face 8a of the polishing plate, then working liquid is stored in the first groove 12 during polishing work for the purpose of compensation. Second spiral groove 13 shallower than the first groove 12 is etched concentrically with the first groove 12 at a portion of the polishing face 8a where the first groove 12 is not etched. The second groove 12 etched in the polishing face 8a promotes dynamic pressure fluid bearing function. When the second grooves 13 are provided alternately with flat sections 23, occurrence of burr of the second groove 13 can be avoided during polishing work, and the polishing work can be polished accurately with high accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a polishing apparatus suitable for polishing brittle materials such as ferrite, semiconductor wafers, and optical glass.

(Prior technology) Recently, float polishing has been used to process the flat surfaces of workpieces such as ferrite, semiconductor wafers, and optical glass with high efficiency without producing a degraded layer or impairing the material properties. Ultra-precision processing is being carried out. In this float polishing, the workpiece and polishing plate are
By rotating in the machining fluid containing fine OA powder particles, the workpiece floats above the polishing plate and is covered with fine powder particles that accompany the flow of machining fluid that passes through the gap between the workpiece and the polishing plate. Ultra-precision machining is performed by colliding with the workpiece (Hideo Tsuwa, Yoshiharu Namba,
T. Wada: Development of an ultra-precision surface polishing machine, Proceedings of the 1981 Academic Conference Autumn Conference (1981), No. 307
(see page).

By the way, the above-mentioned boring plate is made of tin,
The surface of this plate facing the workpiece has a groove width of 1 mm and a depth of 0 mm.
After cutting a plurality of grooves with a thickness of 5 to 1 tnm and a pitch of 2 mm, for example, in the case of a plate with a diameter of 460 mm, diamond cutting is performed so that the flatness is about 1 μIn. As shown in FIG. 6, the diamond-cut surface of this polishing plate has the shape of the tip of the diamond cutting tool transferred thereto, and has a serrated section in cross-section.

In this case, the serrated portion 4... has a cut remaining portion (B).
... is attached. However, the uncut portion (B), which is a part of the serrated portion, often has burrs. As a result, the particles adhering to the uncut portion (13) are liberated, and when they pass through the gap between the workpiece and the polishing plate together with the machining fluid, they scrape the surface of the workpiece, causing the surface This was a cause of deterioration in processing accuracy such as roughness and flatness.

(Problems to be Solved by the Invention) The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a polishing device capable of highly accurate and highly efficient float polishing.

[Structure of the invention]

(Means and effects for solving the problem) In a polishing device for float polishing, a first groove for retaining machining fluid and a second groove shallower than the first groove are formed by transferring the shape of a diamond cutting edge, This is to prevent deterioration of processing accuracy due to the occurrence of uncut edges.

(Example) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the polishing apparatus of this embodiment.

This device consists of a lower surface plate part (3) that is rotated around an axis (1) in the direction of arrow υ (2), and an upper surface plate that is disposed opposite to this lower surface plate part (3) and is movable up and down. (4), a first rotational drive section (not shown) that rotationally drives the lower surface plate section (3), and a second rotational drive section (not shown) that rotationally drives the upper surface plate section (4). ). However,
The lower surface plate part (3) includes a disc-shaped base (5) and this base (
5) a connecting shaft (6) whose one end is coaxially connected to the lower surface and whose other end is connected; and a disk-shaped support plate (7) coaxially fixed to the upper surface of the base (5); A tin boring plate (8) coaxially supported and fixed to this support plate (7),
The base (5) is made up of a cylindrical side wall plate (9) that is coaxially erected on the upper side edge and forms a processing tank (5a) in which the processing fluid is stored together with the base (5). . The above support plate (
A through hole (It), (11) is drilled in the central part of the force and boring plate (8). Also, the polishing surface (8a) which is the top surface of (8)
has a spiral first groove (12...
are carved concentrically on the bollising plate (8).

These first grooves (12+...) are, for example, diamond-cut with a groove width lit, a depth of 0.5 to 1, and a pitch of 2 m. This has the role of compensating for the shortage of machining fluid (L) in the boring surface (8a).Furthermore, in the portions other than the first grooves (t2...) of the boring surface (8a), there are spiral spirals concentric with these first grooves (t2...). Second grooves 0■... are carved in the shape of the second grooves (
13) ... is, for example, 50 to 100 μm and 10 μm deep.
It was diamond cut with a pitch of 130 μm. The cross section of the second groove (13) is arcuate. On the other hand, the upper surface plate part (4) includes a disk-shaped adhesive plate 04) to which the plate-shaped workpiece (5) is bonded;
A support shaft a is coaxially connected to the back of this adhesive plate αa,
It consists of a bearing mechanism (not shown) that supports this support shaft (1ω) so that it can move up and down in the vertical direction, that is, in the direction of the arrow (t6J). It is designed to be rotationally driven around αη in the direction of the arrow α through the bearing mechanism.The diameter of the adhesive plate (I) is also smaller than the radius of the boring plate (8), and The supporting axis σ9 is.

The entire surface to be polished (lI) of the workpiece (1,) is provided at a position facing the boring plate (8). By the way, the second groove α level... is shown in FIG. As shown, a diamond cutting tool (20) having the same cutting edge shape as the second groove (13... For example, a depth of 10 μm on the bolling surface (8a).
The polishing plate (8) is cut at a predetermined feed rate (for example, 0.3ii/r) in the direction of the arrow CD, which is the radial direction of the polishing plate (8).
It was created by applying a feed with ev, ),
The tip shape of the diamond bit (201) is faithfully transferred. Next, the polishing surface (8a) on which the second groove α needle... is formed is polished at a feed rate of 0.3 h/rev,
and rotated at a rotation speed of 30 Orpm, and the surface roughness was 0.
．． Diamond cutting is performed to a flatness of approximately 1 μm and a Rz of 1 μm or less. Therefore, the boring surface (8a) has a flat portion Qυ with a surface roughness of 0.1 μmRz or less, and the first and second grooves (121) carved in the flat portion C21). , (13)-,-.

Next, the operation of the polishing apparatus having the above configuration will be described.

First, a machining liquid (g) is supplied into a machining tank (5a) made of pure water containing ultrafine particles such as Sin having a nominal diameter of 70A so as to completely cover the polishing plate (8). Next, the upper surface plate part (4) is lowered, and the workpiece (5) bonded to the adhesive plate α is immersed in the processing liquid (L), and then brought close to the boring plate (8). . The workpiece (5) has been processed to have a surface roughness of 0.1 μmRz or less and a flatness of μm. Subsequently, the support shaft aω is rotated in the direction of arrow α at 60 to 20 Orpm, and the base (5) is rotated in the direction of arrow (2) at 60 to 20 Orpm. Then, the distance between the polishing plate (8) and the surface of the workpiece is several microns because the boriding plate (8) floats due to the dynamic pressure fluid lubrication effect of the machining fluid (g).
A gap (2〃) of m is created, and a film of machining liquid (2) is created in this gap. Therefore, the boring plate (8)
Since it does not come into direct contact with the workpiece (1), the wear of the borer plate (8) is extremely low. Furthermore, the surface to be polished (1
1, by transferring the integrated flatness of the polishing plate (8), the flatness of the boriding surface is also improved. In particular, it is engraved on the boring surface (8a).
The second grooves H... have a role of promoting the hydrodynamic bearing action. And this second groove α3)...
are provided alternately with flat parts (c)...
During the boring process, the surface to be polished (1!J
without damaging it. If it is a gas, the machining mechanism in the machining liquid film 04 is Si, which is ultrafine particles with a nominal diameter of 70A.
n, collides with the workpiece (1), causing the surface to be polished (11
The surface to be polished (1
! The surface atoms constituting j are removed. Therefore, if 8i0. When a coarse particle or other fallen object collides with the surface to be polished 09, the workpiece (5)
plastic deformation and destruction, resulting in relatively large scratches. However, in this embodiment, it is possible to prevent the occurrence of falling bodies, which is a problem. Therefore, in combination with the ability to remove secondary damage, extremely high polishing precision can be obtained with high efficiency. Incidentally, FIG. 4 shows the prior art and this embodiment in which the second grooves Q3) are not provided, and it can be seen that the surface roughness is significantly improved. In other words, the surface roughness of the conventional technology is 3.5AR.
M.S.

18.5 A Rmax, whereas the surface roughness of this example is 2.3 ARMS and 13.4 A Rmax.
improved to a certain extent. In particular, it is thought that the reason for the small variation in data is that there is no sudden damage caused by the outbreak of Paris.

In the above embodiment, the shape of the second grooves (I3) is spiral, but the shape may be arbitrarily selected, such as multiple concentric circles or a lattice shape. Further, the first groove a may also be in the form of multiple concentric circles, a lattice shape, or the like. Furthermore, the material of the borising plate (8) may also be copper or a copper-based alloy, nickel or a nickel-based alloy. Furthermore, as another example, as shown in FIG. 5, multiple second grooves a3 may be formed by diamond cutting so as to be adjacent to each other so that no uncut portions are left. In this case, although the flat portion (c) of the previous embodiment does not exist, there is no uncut portion, so there is no occurrence of burr caused by this, and the polishing accuracy is improved in this case as well.

〔Effect of the invention〕

In the polishing apparatus of the present invention, in addition to the first groove, a minute second groove is provided on the flat surface on which the first groove is provided, so that extremely high polishing precision can be obtained with high efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a polishing apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1, FIG. 3 is an explanatory diagram of the groove forming method, and FIG. 4 is a conventional technique. FIG. 5 is an explanatory diagram of the main parts of a polishing apparatus according to another embodiment of the present invention, and FIG. 6 is a graph showing a comparison with conventional technology W: workpiece. (L): Processing liquid. (8): Borising grate (polishing plate). (Country: 1st groove. (13) : 2nd groove. C3B) : Boring surface (polished surface). Agent Patent Attorney Noriyuki Chika Yudo Mitsuyuki Matsuyama Figure 5 Figure 6

Claims (2)

[Claims] (1) A polishing plate that has a flat polished surface and a first groove in which the machining liquid stays, and a holder that holds the workpiece so that it can be moved up and down and comes into contact with the polishing surface. means and
and a drive means for relatively sliding the workpiece held by the holding means along the polishing surface, the workpiece being floated in the machining liquid interposed above the polishing surface. 1. A polishing device for polishing, characterized in that a second groove shallower than the first groove is provided in a portion of the polishing surface where the first groove is not formed. (2) The polishing device according to claim 1, wherein the second groove is formed by transferring the shape of the cutting edge of the diamond tool by cutting with a diamond tool.