JP2944176B2 - Ultra-precision polishing method and polishing apparatus for wafer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention eliminates a taper error and a convex error of a polished surface of a wafer when processing a wafer such as a silicon wafer into a distortion-free mirror surface. The present invention relates to an ultra-precision polishing method and a polishing apparatus for a wafer, which can obtain a wafer having a high flatness without variation and can precisely finish the wafer to a target thickness.

[Prior Art] Conventionally, as one method of manufacturing a wafer with high flatness while eliminating variations in wafer thickness, Japanese Patent Application No.
As described in No. 0310 (“Wafer manufacturing method”), an alkaline solution in which an abrasive composed of fine particles of high-purity quartz is dispersed is supplied to the surface of a smooth platen, and the wafer is placed on the surface of the platen. There is known a method in which a surface to be polished is pressed and a wafer and a surface plate are rubbed in this state to grind the wafer surface without distortion.

[Problems to be Solved by the Invention] With the increase in the degree of integration of semiconductor devices, higher precision is required for the flatness of the wafer. Particularly, the wafer used for SOI has a thickness variation of 1 μm or less and a thickness of 1 μm or less. It is required that the accuracy of the absolute value of is not more than 1 μm.

However, in the range of the conventional technology described above, a plane for holding a wafer serving as a reference during polishing (hereinafter, referred to as a polishing reference plane) and a surface of a surface plate are mechanically controlled in parallel, and However, there is a certain limit in controlling the distance between the polishing reference plane and the surface of the surface plate to a desired finished thickness in terms of the structural accuracy and control of the polishing apparatus. The occurrence of a so-called taper error in which the polished surface is inclined with respect to the polished reference surface is unavoidable, albeit minute, and it has been difficult to reduce the thickness variation to 1 μm or less. Further, it has been extremely difficult to converge the absolute value of the thickness of the wafer to 1 μm or less from the limit of the accuracy in determining the stop position of the polishing apparatus.

In the conventional technique using a polishing cloth, the surface to be polished of the wafer has a convex lens shape, and the thickness variation of the wafer is 1 μm.
In order to reduce the number to m or less, it was necessary to solve this problem.

On the other hand, conventionally, polishing using a wafer polishing cloth
The primary polishing to the required dimensions and the secondary polishing to improve the surface roughness of the surface to be polished are performed separately, and since each polishing uses a separate polishing machine and abrasive material ,
There were many inefficient parts, such as the need for complicated setup changes such as wafer transfer during a series of polishing processes. For this reason, it has been demanded to perform a series of polishing operations on one platen so as not to mix different abrasives in order to simplify automation of the polishing process.

Further, the alkaline component in the polishing liquid etches silicon, and thus impairs the surface roughness of the obtained polished surface. In order to avoid this, it has been required to perform the cleaning very quickly after the polishing is completed. Dust mixed from the outside during polishing is a cause of scratches on the polished surface, so-called scratches.

The present invention has been made in view of the above circumstances,
The surface of the surface plate and the polishing reference surface of the wafer are always kept in parallel, eliminating the taper error of the wafer, and the polishing of the surface of the surface plate and the wafer, without being affected by the structural accuracy of the machinery and the limitations of control. An ultra-precision polishing method and a polishing apparatus for a wafer that can surely match the gap with the reference plane to the finished thickness dimension of the wafer are provided, and the surface of the wafer is not polished into a convex lens shape, and the scratch Providing a polishing device that can prevent the dust that causes the contamination of the polishing area, and, with a single polishing machine, the primary polishing and the secondary polishing described above can be performed, and after polishing It is an object of the present invention to provide a polishing apparatus capable of continuously cleaning a wafer.

[Means for Solving the Problems] In order to solve the above problems, in the ultra-precision polishing method for a wafer of the present invention, a flange portion surrounding an outer peripheral surface of a wafer is formed on a wafer holding member, and the flange portion is fixed. A pressure-receiving surface parallel to the other end of the wafer and receding from the above-mentioned one end of the wafer by more than the polishing allowance of the wafer is formed on the end surface facing the plate surface, and the polishing liquid is discharged to the pressure-receiving surface. A plurality of discharge portions are formed along the circumferential direction, and the wafer is polished while discharging a polishing liquid from these discharge portions toward the surface of the surface plate.

Further, in order to realize the above-mentioned polishing method, the polishing apparatus of the present invention is provided with a holding member for holding the wafer at a position facing the surface of the surface plate, and the holding member has a flange portion surrounding the outer peripheral surface of the wafer. Forming a pressure-receiving surface parallel to the other end surface of the wafer and receding from the one end surface of the wafer to the other end surface side more greatly than the polishing allowance of the wafer, on the end surface side of the flange portion facing the surface plate. A plurality of discharge portions for discharging the polishing liquid were formed in the pressure receiving surface along the circumferential direction.

Further, in order to continuously perform the primary polishing, the secondary polishing and the cleaning on one platen, in the polishing apparatus having the above-described configuration, a plurality of wafers independent of each other are placed on one platen. It is preferable to provide a plurality of holding members that can hold and selectively discharge different polishing liquids or cleaning liquids in the circumferential direction of the platen.

In order to solve the above problems, in the polishing apparatus of the present invention described above, a plurality of grooves are provided in parallel on the surface of the surface plate,
It is preferable to set the interval between these grooves to 10 mm or less.

[Operation] According to the above-described ultra-precision polishing method and polishing apparatus for a wafer, the reaction force of the polishing liquid pressure discharged from the outer peripheral side of the holding member is applied to the pressure receiving surface during polishing to push the holding member up from the surface of the surface plate. The power to try works.

When the holding member is tilted obliquely with respect to the surface of the surface plate, the polishing liquid pressure on the side where the gap becomes narrower becomes relatively high, so that the force for returning the gap to the original position by widening the gap becomes smaller. As a result, the pressure receiving surface is always kept parallel to the surface of the surface plate. Therefore, the other end surface of the wafer that is parallel to the pressure receiving surface is also kept parallel to the surface of the surface plate. As a result, one end surface of the wafer is polished exactly parallel to the other end surface.

On the other hand, as the polishing progresses, the distance between the pressure receiving surface and the surface of the surface plate becomes narrower, so that the polishing liquid pushes up the holding member further, and finally, the polishing which presses the wafer against the surface plate. Reach equilibrium with pressure. As a result, the polishing pressure does not act on the wafer, and the polishing is effectively stopped. In other words, the polishing is practically stopped at the position corresponding to the desired finished thickness without mechanically releasing the force for pressing the wafer against the surface of the surface plate, so that a high absolute thickness accuracy can be obtained.

Further, since the gap between the pressure receiving surface of the flange portion surrounding the outer peripheral surface of the wafer and the surface of the surface plate is filled with the polishing liquid, the polishing region defined on the inner peripheral side of the flange portion and the outside of the holding member are separated. It is isolated and dust and the like do not enter the polishing region from the outside, and as a result, generation of scratches is also avoided.

Then, when the desired polishing liquid or cleaning liquid can be selectively discharged from each discharge section in one holding member, once the wafer is placed on the surface plate, the polishing section is advanced while the polishing proceeds. The primary polishing and the secondary polishing can be performed continuously by changing the polishing liquid discharged from the first polishing. Further, if the cleaning liquid is discharged from the discharge part after the second polishing, the wafer can be cleaned immediately after polishing and the wafer can be protected from etching by an alkali component.

Next, in another polishing apparatus having the above configuration, the polishing liquid flowing through the groove portion and the one end surface of the wafer come into contact with each other in accordance with the relative movement between the one end surface of the wafer and the surface of the surface plate. One end side is uniformly polished over the entire surface.

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIGS. 1 to 3 show a polishing apparatus used in this embodiment, and reference numeral 1 in the figures denotes a surface plate. The surface plate 1 is formed in a substantially disk shape in appearance, and its surface 1a is formed as a smooth surface orthogonal to the axis of the surface plate. A drive shaft 2 for connecting the base 1 and a drive source (not shown) such as a motor is connected to a center portion on the back surface side of the base 1, and the base 1 is centered on the axis by the drive shaft 2. As a specific direction (arrow A direction)
It is designed to be driven to rotate.

On the other hand, as shown in FIGS. 1 and 2, a plurality of (four in the figure) holding members 3 are arranged at equal intervals in the circumferential direction at positions facing the surface of the surface plate 1. . These holding members 3 are provided for holding a disc-shaped wafer 4 placed on the surface 1a of the platen, and are provided on a plate 5 having a holding surface 5a in close contact with a polishing reference surface 4a of the wafer 4. A flange 6 surrounding the outer peripheral surface of the wafer 4 is integrally formed on the outer peripheral side, and a support shaft 7 for supporting the holding member 3 is provided at the center of the upper end of the plate 5.

Here, as shown in FIGS. 1 and 3, the holding surface is provided on the end surface side of the flange portion 6 facing the surface 1a of the platen.
A pressure receiving surface 8 is formed which is parallel to 5a and retreats by a predetermined amount S toward the holding surface 5a side from the polished surface 4b of the wafer 4 before polishing placed on the surface 1a of the platen. The retreat amount S of the pressure receiving surface 8 is set to be slightly larger than the polishing allowance of the wafer 4 which is in close contact with the holding surface 5a, and more specifically, 1 μm from the polishing allowance.
A range larger by about m to 50 μm is preferably used. If the retreat amount S is less than the polishing allowance +1 μm, the pressure receiving surface 8 may come into contact with the surface of the surface plate 1a and be polished when the holding member 3 is inclined at the final stage of polishing. If S exceeds the polishing allowance +50 μm, there is a possibility that a sufficient restoring force of the holding member 3 due to the pressure of the polishing liquid described later may not be obtained.

A plurality of discharge units 9 for discharging the polishing liquid are formed on the pressure receiving surface 8 at equal intervals in the circumferential direction. These discharge portions 9 are composed of concave portions 10 that slightly depress from the pressure receiving surface 8 and circular nozzle ports 11 formed at the center of the bottom surface 10a of these concave portions 10, and the shapes and dimensions of each concave portion 10 are equal to each other. Stipulated. Further, the nozzle port 11 is communicated with a polishing liquid flow path 12 formed inside the flange portion 6.

The polishing liquid channel 12 is connected to a polishing liquid supply device (not shown), and a high-purity abrasive (for example, a particle size of 0.02 μm
An alkaline polishing liquid having a pH of about 10 to 12 in which high-purity SiO ₂ particles of about 10 to 12 is dispersed is supplied. Further, the portion of the polishing liquid flow path 12 connected to the nozzle port 11 is gradually narrowed in the radial direction as approaching the nozzle port 11, so that the pressure of the polishing liquid discharged from the nozzle port 11 is increased.

The support shaft 7 is connected to a drive unit (not shown) provided above the surface plate 1 via a coupling (not shown) so that the support shaft 7 can rotate about an axis and can move up and down. . As the above-mentioned coupling, for example, a known coupling such as a universal joint that allows a deviation of the axis between the two connected shafts is used, whereby the inclination of the support shaft 7 and thus the holding member 3 with respect to the surface 1a of the platen is achieved. Is allowed to vary within a certain range.

Next, a procedure for polishing the wafer 4 using the polishing apparatus having the above configuration will be described.

In order to polish the wafer 4, the wafer 4 is first mounted on the holding member 3 with its polished surface 4b facing downward, and the wafer 4 is held in a state where the polishing reference surface 4b and the holding surface 5a are in close contact with each other. Next, the polishing liquid is supplied to the polishing liquid flow path 12 in the holding member 3 to discharge the polishing liquid from the nozzle port 11 of the holding member 3 toward the surface 1a of the platen. The discharge pressure of the polishing liquid at this time is preferably about 1 to 10 kg / cm ² .

Subsequently, the holding member 3 is pressed toward the surface 1a of the surface plate to make the surface 4b to be polished of the wafer 4 and the surface 1a of the surface plate 100-500 g / cm.
Crimping with about ² pressure. Thereafter, the polished surface 4b of the wafer 4 and the surface 1a of the surface plate are rubbed by rotating the surface plate 1 and the holding member 3 around their respective axes, thereby polishing the wafer 4. Then, when the surface to be polished 4b is removed by a predetermined polishing allowance, the rotation of the platen 1 and the holding member 3 is stopped, and the pressing of the holding member 3 is released to finish the polishing.

Here, in the process of polishing in the above procedure, if the pressure receiving surface 8 is inclined obliquely with respect to the surface of the surface plate 1a, a gap between the pressure receiving surface 8 and the surface of the surface plate 1a is generated. Since the polishing liquid discharged from the discharge unit 9 tends to stay in the concave portion 10 in the region where the interval is narrow, the polishing liquid pressure in the concave portion 10 becomes relatively high, and the pressure receiving surface is accordingly increased. 8
(Hereinafter, referred to as a restoring force) is generated to widen the distance between the platen surface 1a and the surface 1a. The restoring force becomes smaller as the inclination of the pressure receiving surface 8 with respect to the surface 1a decreases, and when the distance between the pressure receiving surface 8 and the surface 1a becomes constant over the entire circumference, that is, the pressure receiving surface 8 And when the surface plate 1a becomes parallel.

Thus, according to this embodiment, the surface 1a of the pressure receiving surface 8
The restoring force for returning the pressure receiving surface 8 to a position parallel to the surface of the surface plate 1a in accordance with the degree of inclination acts on the holding member 3, so that the pressure receiving surface 8 and the holding surface parallel to the pressure receiving surface 8 are applied.
5a is always kept parallel to the platen surface 1a. Therefore,
The polishing reference surface 4a of the wafer 4 which is in close contact with the holding surface 5a of the holding member 3 is also maintained in a state parallel to the surface 1a during polishing. As a result, the polished surface 4b of the wafer 4 to be pressed against the platen surface 1a is always polished in parallel with the polishing reference surface 4a, and the occurrence of a taper error is greatly suppressed.

On the other hand, as the thickness of the wafer 4 becomes thinner as the polishing proceeds, the distance between the pressure receiving surface 8 and the surface 1a of the platen gradually decreases.
It gradually rises even if no inclination occurs. As the polishing proceeds further, the distance between the pressure receiving surface 8 and the surface 1a of the platen becomes narrower, and finally, the force of the holding member 3 being pushed back by the pressure of the polishing liquid discharged from the discharge portion 9 and the wafer 4 Of the wafer 4 reaches the equilibrium state, and the force of pressing the polished surface 4b of the wafer 4 against the platen surface 1a is lost. Polishing stops. Therefore, by appropriately adjusting the retreat amount S (see FIG. 1) of the pressure receiving surface 8 so as to obtain the equilibrium state when the polishing amount of the wafer 4 reaches the target value,
Polishing can be accurately finished at a desired position irrespective of the stopping position of the polishing apparatus, and as a result, high thickness accuracy can be obtained.

Further, in the present embodiment, the gap between the pressure receiving surface 8 and the surface of the surface plate 1a is filled with the polishing liquid discharged from each discharge unit 9 during polishing of the wafer 4, so that the outside of the holding member 3 and the flange portion 6 is separated from the polishing area defined inside, so that external dust and the like cannot enter the polishing area. Therefore, the effect that scratches do not occur on the surface of the wafer 4 can be obtained.

In addition, the liquid that is going to enter the polishing area while adhering to the surface 1a of the surface of the platen with the rotation of the surface plate 1 is eliminated by the liquid discharged from the nozzle port 11 and is discharged from the nozzle port 11 to the polishing area. Only liquid is supplied. Therefore,
Even if different polishing liquids and cleaning liquids are discharged from the nozzle port 11 of the holding member 3 holding each wafer 4, they do not enter the polishing area of another wafer 4. Therefore, the first polishing for polishing the wafer 4 to a required size by one polishing apparatus and the second polishing for improving the surface roughness can be achieved without transferring the wafer 4. Further, after the polishing is completed, the polishing liquid is switched to the cleaning liquid, and the cleaning can be immediately performed on the surface plate. Therefore, the etching of the polished surface 4b of the wafer 4 by the alkali component can be easily avoided. Thus, according to the polishing apparatus of this embodiment, automation of wafer polishing can be significantly simplified.

The above embodiment is merely an example, and it goes without saying that the present invention is not limited to the above configuration. For example, the number of the holding members 3 can be changed to three or less or five or more according to the size of the platen 1 and the diameter of the wafer 4, and the configuration of the holding members 3 can be variously changed.

In addition, the number of the discharge portions 9 can be appropriately changed. Particularly, when the number of the discharge portions 9 is increased, the restoring force is subdivided in the circumferential direction, so that the pressure receiving surface 8 and the platen surface 1a are more securely maintained in parallel. be able to. In addition, the concave portion 10 is not necessarily required in the discharge portion 9, and may be omitted when a sufficient restoring force can be obtained simply by opening a large number of nozzle ports 11 on the pressure receiving surface 8.

(Experimental Example) The polishing apparatus shown in FIGS. 1 to 3 was actually manufactured,
The wafer was polished according to the above procedure, and the taper error and the thickness error were measured. The results at this time are shown in FIG. 4 and FIG. The taper error is represented by a difference t in thickness between the thinnest portion and the thick portion of the wafer 4, as shown in FIG. The diameter of the wafer 4 was 6 inches, the target finished thickness of the wafer 4 was 650 μm, and an alkaline silica suspension was used as a polishing liquid.

As is clear from FIG. 4 (a), the conventional polishing method has a maximum taper error of 1.2 μm, whereas the present invention has a maximum taper error of only 0.3 μm, which significantly improves the taper error. can do. In addition, as shown in FIG. 5, the error of the absolute thickness of the wafer is conventionally 2.
While an error exceeding 0 μm has occurred, the present invention has an error of only about 0.5 μm, and it has been confirmed that there is a remarkable effect in eliminating a thickness error.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, only the surface plate 1 of the above-described first embodiment is changed, and other components are the same as those of the first embodiment. Accordingly, in the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. For components other than the surface plate, refer to FIGS. 1 to 3. .

As shown in FIGS. 6 and 7, in the present embodiment, a plurality of grooves 21 parallel to each other are formed on a surface 20a of a base 20 having a substantially cylindrical shape.
Are engraved vertically and horizontally, thereby dividing the surface of the surface plate 20a into a square mesh. Here, each of the groove portions 21 has a cross-sectional shape that is depressed in an arc shape toward the back surface side of the surface plate 20, and each cross-sectional dimension is constant over the entire length of the groove portion 21 and all the groove portions 21 are formed. Are defined equally. The depth h of the groove 21 is appropriately determined according to the diameter of the platen 20 and the like, but is preferably set in the range of 20 to 200 μm as much as possible. If the groove depth h is less than 20 μm, the polishing liquid may not sufficiently spread to the polished surface 4b side of the wafer 4, while if the groove depth h exceeds 200 μm, the groove 21
This is because the polishing liquid flowing therethrough does not come into contact with the polished surface 4b of the wafer 4 and hydrostatic pressure leakage occurs.

Further, the distance d between the grooves 21 is set equally between all the grooves 21. This interval d is also appropriately determined according to the diameter of the wafer 4 to be polished and the like.
It is preferable to set the thickness to 5 mm or less. If the groove interval d exceeds 10 mm, the support of the wafer 4 during polishing becomes unstable, and the accuracy of the wafer 4 may be rather deteriorated.

Thus, in order to polish the wafer 4 by the polishing apparatus having the above configuration, as in the first embodiment described above,
Each wafer 4 is held by the holding member 3 and the surface of the platen
A polishing liquid is supplied to 20a, and thereafter, the polishing target surface 4
The holding member 3 and the platen 20 are rotated while the b is pressed against the platen surface 20a to cause friction between the polished surface 4b of the wafer 4 and the platen surface 20a.

Here, in the present embodiment, the grooves 2 are meshed on the surface 20a of the surface plate.
Since the surface 1 is formed, even when the surface 20a of the surface plate and the surface 4b to be polished of the wafer 4 are in close contact with each other, the polishing liquid flowing through the groove 21 due to the relative movement between the wafer 4 and the surface plate 20 is removed. And the polishing surface 4b is uniformly polished over the entire surface. Therefore, the polished surface 4b of the wafer 4 is not polished in a convex shape, and as a result,
The flatness of the wafer 4 can be further improved in combination with the accuracy improving effect of the first embodiment described above. Incidentally, when the groove 21 is not provided, the polishing liquid does not reach the center of the polished surface 4b of the wafer 4 which is in close contact with the surface of the surface plate, so that the polished surface 4b tends to be polished in a convex shape.

In the present embodiment, the grooves 21 are particularly arranged in a mesh shape, but the arrangement may be changed as needed as long as the distance d can be maintained.

(Experimental Example) The groove 21 shown in FIG. 6 was formed on each of the surface plate of the conventional polishing apparatus and the surface plate of the first embodiment, and the wafer was actually polished. At this time, surface plates having different groove intervals were prepared, and the relationship between the groove interval and the convex error was measured. The results are shown in FIG. The value of the convex error is the eighth.
As shown in FIG. 2B, the height difference between the central portion and the peripheral portion of the wafer 4 was represented by e.

As shown in FIG. 8A, the conventional polishing apparatus and the first polishing apparatus
In any of the polishing apparatuses of the embodiments, the convex error decreases as the groove interval d decreases, and particularly in the range where the groove interval is 5 mm or less, the convex error almost disappears and the wafer 4 is polished flat. It became clear. It is also apparent that the effect is further enhanced by applying the present invention to the polishing apparatus of the first embodiment.

[Effects of the Invention] As described above, according to the ultra-precision polishing method and the polishing apparatus for a wafer of the present invention, the pressure of the polishing liquid discharged from the discharge unit is applied to the pressure receiving surface, thereby being fixed to the other end surface of the wafer. Since the board surface is always kept parallel, the taper error of the wafer can be eliminated.

Also, as the polishing liquid pressure pushes up the holding member and the pressing force of the holding member against the surface of the platen reach an equilibrium state with the progress of the polishing, the polishing automatically stops at the target position, The wafer can always be polished with a constant thickness, and the absolute thickness of the wafer can be accurately matched with the target value.

Further, the polishing liquid discharged on the outer peripheral side of the wafer separates the polishing region of the wafer from the outside and prevents the intrusion of dust and the like, so that scratching of the wafer can be avoided.

In addition, by enabling a desired polishing liquid or a cleaning liquid to be selectively discharged from each discharge section in one holding member, the primary, secondary polishing and cleaning with the cleaning liquid can be performed on the wafer on the one platen. It can be performed continuously without performing troublesome setup change such as transfer, and the automation of wafer polishing can be further simplified.

In addition, according to another polishing apparatus of the present invention, the polishing liquid flowing in the groove on the surface plate uniformly polishes the surface to be polished of the wafer over the entire surface, so that the wafer is polished in a convex shape. And the flatness of the wafer is greatly improved.

[Brief description of the drawings]

FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is an axial sectional view of the apparatus, FIG. 2 is a perspective view showing a schematic configuration of a polishing apparatus, and FIG. FIG. 1 is a view from the direction of arrow III, FIG. 4 (a) is a view showing a measurement result of the taper error of the wafer according to the experimental example of the first embodiment, and FIG. 4 (b) is a view showing the taper error of the wafer. FIG. 5 is a view showing a measurement result of a thickness error of a wafer according to an experimental example of the first embodiment. FIGS. 6 and 7 show a second embodiment of the present invention.
FIG. 6 is a plan view of the surface plate, FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6, and FIG. 8 (a) shows a measurement result of the convexity error of the wafer according to the experimental example of the second embodiment. FIG. 1B is a diagram showing a convex error of a wafer. 1 · 20 · · · surface plate, 1a · 20a · · · surface of the surface plate, 3 · · · · holding member, 4 · · · wafer, 6 · · · flange portion, 8 · · · pressure receiving surface, 9 · · · discharge section, 21 · · · groove portion. .

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-60127 (JP, A) JP-A-1-135474 (JP, A) JP-A-49-132691 (JP, A) 15864 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24B 37/00, 37/04

Claims (4)

(57) [Claims] 1. A holding member for holding a wafer is provided at a position facing a surface of a smooth surface plate, and a flat wafer is mounted on the holding member with one end surface thereof facing the surface of the surface plate. Thereafter, the polishing liquid is supplied to the surface of the surface plate, and the holding member is pressed toward the surface plate to press one end surface of the wafer against the surface of the surface plate. In the ultra-precision polishing method for a wafer, which polishes the wafer by rubbing against the surface of a surface plate, a flange portion surrounding the outer peripheral surface of the wafer is formed on the holding member, and the flange portion faces the surface of the surface plate. On the end surface side to form a pressure receiving surface parallel to the other end surface of the wafer and receding from the one end surface of the wafer before polishing to the other end surface side more than the polishing allowance of the wafer, on this pressure receiving surface,
A plurality of discharge portions for discharging the polishing liquid are formed along the circumferential direction, and the wafer is polished while discharging the polishing liquid from the discharge portions toward the surface of the surface plate. . A holding member for holding the wafer at a position facing the surface of the surface plate, a flange portion surrounding the outer peripheral surface of the wafer is formed on the holding member, and the flange portion faces the surface plate. On the end surface side to form a pressure receiving surface parallel to the other end surface of the wafer and receding more than the polishing allowance of the wafer from one end surface of the wafer before polishing to the other end surface,
A polishing apparatus in which a plurality of discharge portions for discharging a polishing liquid are formed in the pressure receiving surface along a circumferential direction. 3. A polishing apparatus according to claim 2, wherein a holding member for holding a plurality of wafers independent of each other and selectively discharging different polishing liquids or cleaning liquids is provided on one platen. A polishing apparatus, wherein a plurality of polishing apparatuses are provided along a direction. 4. A polishing apparatus according to claim 2, wherein a plurality of grooves are provided in parallel on the surface of said platen, and an interval between said grooves is set to 10 mm or less. apparatus.