U.S. patent application number 09/044146 was filed with the patent office on 2001-09-06 for polishing apparatus including holder and polishing head with rotational axis of polishing head offset from rotational axis of holder and method of using.
Invention is credited to IKEDA, OSAMU, NISHIMURA, MATSUOMI, OHTA, SATOSHI, UCHIYAMA, SHINZO.
Application Number | 20010019934 09/044146 |
Document ID | / |
Family ID | 26408059 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010019934 |
Kind Code |
A1 |
NISHIMURA, MATSUOMI ; et
al. |
September 6, 2001 |
POLISHING APPARATUS INCLUDING HOLDER AND POLISHING HEAD WITH
ROTATIONAL AXIS OF POLISHING HEAD OFFSET FROM ROTATIONAL AXIS OF
HOLDER AND METHOD OF USING
Abstract
The present invention provides a polishing apparatus comprising
a holding means for holding a polished body with a polished surface
thereof facing upwardly, and a polishing head for holding a
polishing pad having a polishing surface having an area smaller
than an area of the polished surface while contacting the polishing
pad with the polished surface and for rotating the polishing pad
around its rotation axis, and wherein the polishing head is
provided with a drive means for revolving the polishing pad around
a revolution axis, and the revolution axis and the rotation axis
are positioned so that a distance between the revolution axis and
the rotation axis becomes smaller than a radius of the polishing
pad.
Inventors: |
NISHIMURA, MATSUOMI;
(OMIYA-SHI, JP) ; IKEDA, OSAMU; (YOKOHAMA-SHI,
JP) ; OHTA, SATOSHI; (TOKYO, JP) ; UCHIYAMA,
SHINZO; (UTSUNOMIYA-SHI, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
26408059 |
Appl. No.: |
09/044146 |
Filed: |
March 19, 1998 |
Current U.S.
Class: |
451/8 ; 451/287;
451/41 |
Current CPC
Class: |
B24B 37/04 20130101;
B24B 41/047 20130101; B24B 49/00 20130101; B24B 57/02 20130101 |
Class at
Publication: |
451/8 ; 451/41;
451/287 |
International
Class: |
B24B 049/00; B24B
051/00; B24B 029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 1997 |
JP |
9-068160 |
Mar 17, 1998 |
JP |
10-066856 |
Claims
What is claimed is:
1. A polishing apparatus comprising: a holding means for holding a
polished body with a polished surface thereof facing upwardly; and
a polishing head for holding a polishing pad having a polishing
surface having an area smaller than an area of the polished surface
while contacting said polishing pad with the polished surface and
for rotating said polishing pad around its rotation axis; and
wherein said polishing head is provided with a drive means for
revolving said polishing pad around a revolution axis, and the
revolution axis and the rotation axis are positioned so that a
distance between the revolution axis and the rotation axis becomes
smaller than a radius of said polishing pad.
2. A polishing apparatus according to claim 1, wherein said holding
means can be rotated.
3. A polishing apparatus according to claim 1, wherein the
revolution axis of said polishing head can be shifted along the
polished surface.
4. A polishing apparatus according to claim 1, wherein the
revolution axis is shifted to a predetermined position of the
polished body in accordance with a surface configuration of the
polished body.
5. A polishing apparatus according to claim 1, wherein the
revolution axis of said polishing head is shifted to a
predetermined position of the polished body in accordance with a
surface configuration of the polished body, by rotation of said
holding means and by shifting movement of the revolution axis.
6. A polishing apparatus according to claim 1, wherein said
polishing head includes a detection head for detecting the surface
configuration of the polished body.
7. A polishing apparatus according to claim 1, wherein said
polishing head includes a variable means for varying a distance
between the revolution axis and the rotation axis.
8. A polishing apparatus according to claim 1, wherein said
polishing head has a supply passage for supplying abrasive agent
through said polishing pad.
9. A polishing method in which a polished body is rested on a
holding means with a polished surface thereof facing upwardly and
the polished surface is polished by rotating a polishing pad having
a polishing surface having an area smaller than an area of the
polished surface while contacting said polishing pad with the
polished surface, comprising the steps of: rotating said polishing
pad around the rotation axis; and revolving said polishing pad
around the revolution axis positioned so that a distance between
the revolution axis and the rotation axis becomes smaller than a
radius of said polishing pad.
10. A polishing method according to claim 9, further comprising a
step of shifting the revolution axis to a predetermined position of
the polished body in accordance with a surface configuration of the
polished body.
11. A polishing method according to claim 9, further comprising a
step of shifting the revolution axis of said polishing head to a
predetermined position of the polished body in accordance with a
surface configuration of the polished body, by rotation of said
holding means and by shifting movement of the revolution axis.
12. A polishing method according to claim 9, wherein the distance
between the revolution axis and the rotation axis is determined in
accordance with a dimension of an element of an element substrate
which is the polished body.
13. A polishing method according to claim 9, wherein the element
substrate is a semi-conductor wafer, a glass substrate or a quartz
substrate.
14. A polishing apparatus according to claim 8, wherein said supply
passage passes through the rotation axis, and a supply tube for
supplying abrasive agent which is disposed within said supply
passage is connected to an abrasive agent supplying source for
supplying the abrasive agent via a rotary joint.
15. A polishing apparatus according to claim 14, wherein said
supply tube passes through the revolution axis.
16. A polishing method according to claim 9, wherein the polished
body is polished while supplying the abrasive agent from a small
hole formed in said polishing head for holding said polishing
pad.
17. A polishing method according to claim 16, wherein a supply tube
connected to said small hole supplies the abrasive agent from said
small hole to the polished body.
18. A polishing method according to claim 17, wherein said supply
tube passes through the revolution axis.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a precise polishing
apparatus and a precise polishing method for polishing a substrate
such as a wafer with high accuracy.
[0003] 2. Related Background Art
[0004] Recently, fine arrangement and multi-layer wiring of
semi-conductor devices have been progressed, and, thus, there has
been requested to provide precise polishing apparatuses for
flattening a surface of a semi-conductor wafer made of Si, GaAs,
InP or SOI or a glass or quartz substrate (so-called element
substrate) having transistor with high accuracy. Among them, as a
precise polishing apparatus for accurately flattening the surface
of the substrate such as a wafer on which semi-conductor elements
are formed, a chemical mechanical polishing (CMP) apparatus is
known.
[0005] Conventional CMP apparatuses can be divided into two types
shown in FIGS. 7 and 8.
[0006] (1) FIG. 7 is a schematic view of a polishing work portion
of the CMP apparatus in which the polishing (abrasion) is effected
with a polished surface of a wafer 100 facing downwardly.
[0007] As shown in FIG. 7, the wafer 100 is held with the polished
surface (surface to be polished) thereof facing downwardly, and the
wafer 100 is polished by urging the wafer against a polishing pad
502 having a diameter larger than that of the wafer while rotating
the wafer. During the polishing, abrasive agent (slurry) is
supplied onto the polishing pad 502.
[0008] In the apparatus of this kind, as methods for holding the
wafer onto a wafer chuck 501, vacuum suction or adhesion by using
wax, solution or pure water has been adopted, and, in some cases, a
guide ring is provided on a periphery of the wafer 100 to prevent
deviation of the wafer 100. The diameter of the polishing pad 502
on a polishing table 506 is greater than that of the wafer 100 by
3-5 times, and suspension obtained by mixing fine powder of silicon
oxide with solution of potassium hydroxide is used as the
slurry.
[0009] (2) On the other hand, as shown in FIG. 8, there has been
proposed a technique in which a wafer 100 is held on a wafer chuck
601 having a guide ring and disposed on a wafer table 606 with a
polished surface thereof facing upwardly and the wafer 100 is
polished by using a polishing pad 602 having a diameter smaller
than that of the wafer 100.
[0010] In such polishing apparatus and method, the substrate such
as the present semi-conductor wafer having a diameter of eight
inches can be polished exclusively. However, recently, since fine
arrangement of semi-conductor integrated circuits and large
diameter wafers have been proposed, it is guessed that the wafer
having 8-inch diameter will be replaced by a wafer having 12-inch
diameter in the near future.
[0011] However, in such conventional polishing apparatuses,
although the polishing ability is adjusted by making a thickness
and elasticity of the polishing pad optimum to polish the 8-inch
wafer, in this case, it is difficult to ensure fine adjustment and
uniformity of material of the polishing pad, and, thus, it is very
difficult to polish the large diameter wafer such as 12-inch wafer
with high accuracy.
[0012] In order to solve the above problem, it is considered that
the entire surface of the wafer is firstly polished by using a
rough polishing pad, and, then, a desired portion of the wafer is
polished selectively or preferentially to obtain a desired wafer
surface.
[0013] However, in order to polish the large diameter wafer (having
the diameter of 8 inch or more), there arises the following problem
in the conventional techniques.
[0014] In the conventional polishing apparatuses and methods using
a polishing tool greater than the wafer, a portion of the wafer
which could not be made uniform is very hard to be made more
uniform or be further flattened by using the same method. Further,
in a system in which a polishing tool smaller than the wafer is
used and scan is effected while oscillating the rotating polishing
tool or in a system in which a polishing tool smaller than the
wafer is used and scan is effected while revolving the rotating
polishing tool within a radius range greater than a radius of the
tool and oscillating the tool, although a desired portion of the
wafer can be polished selectively or preferentially, pitch
unevenness due to the scan is apt to be generated, and, it is
difficult to correct such pitch unevenness with high accuracy and
to make the wafer surface uniform and to flatten the wafer surface.
Also in a system, as disclosed in U.S. Pat. No. 4,128,968, in which
a rotating and revolving tool having a sectional configuration of
the polishing becoming maximum around a revolution axis and
gradually decreasing toward the periphery is used, although a
desired portion of the wafer can be polished selectively or
preferentially, pitch unevenness due to the scan is apt to be
generated, and, it is difficult to correct such pitch unevenness
with high accuracy and to make the wafer surface uniform and to
flatten the wafer surface.
SUMMARY OF THE INVENTION
[0015] A first object of the present invention is to provide a
polishing apparatus and a polishing method, in which a large area
substrate can be corrected and polished with high accuracy.
[0016] A second object of the present invention is to provide a
polishing apparatus and a polishing method, in which a desired
portion of a wafer can be corrected selectively or preferentially
with high accuracy by using a tool (polishing pad) smaller than the
wafer to make the wafer more uniform and to further flatten the
wafer.
[0017] To achieve the above objects, according to the present
invention, there is provided a polishing apparatus comprising a
holding means for holding a polished body with a polished surface
thereof facing upwardly, and a polishing head for holding a
polishing pad having a polishing surface having an area smaller
than an area of the polished surface while contacting the polishing
pad with the polished surface and for rotating the polishing pad
around its rotation axis, and wherein the polishing head is
provided with a drive means for revolving the polishing pad around
a revolution axis, and the revolution axis and the rotation axis
are positioned so that a distance between the revolution axis and
the rotation axis becomes smaller than a radius of the polishing
pad.
[0018] In the polishing apparatus, the holding means can be
rotated.
[0019] In the polishing apparatus, the revolution axis of the
polishing head can be shifted along the polished surface.
[0020] In the polishing apparatus, the revolution axis may be
shifted to a predetermined position of the polished body in
accordance with a surface configuration of the polished body.
[0021] In the polishing apparatus, the revolution axis of the
polishing head may be shifted to a predetermined position of the
polished body in accordance with a surface configuration of the
polished body, by rotation of the holding means and by shifting
movement of the revolution axis.
[0022] In the polishing apparatus, the polishing head may include a
detection head for detecting the surface configuration of the
polished body.
[0023] In the polishing apparatus, the polishing head may include a
variable means for varying a distance between the revolution axis
and the rotation axis.
[0024] In the polishing apparatus, the polishing head may have a
supply passage for supplying abrasive agent through the polishing
pad.
[0025] The present invention further provides a polishing method in
which a polished body is rested on a holding means with a polished
surface thereof facing upwardly and the polished surface is
polished by rotating a polishing pad having a polishing surface
having an area smaller than an area of the polished surface while
contacting the polishing pad with the polished surface, comprising
the steps of rotating the polishing pad around the rotation axis,
and revolving the polishing pad around the revolution axis
positioned so that a distance between the revolution axis and the
rotation axis becomes smaller than a radius of the polishing
pad.
[0026] The polishing method may further comprise a step of shifting
the revolution axis to a predetermined position of the polished
body in accordance with a surface configuration of the polished
body.
[0027] The polishing method may further comprise a step of shifting
the revolution axis of the head to a predetermined position of the
polished body in accordance with a surface configuration of the
polished body, by rotation of the holding means and by shifting
movement of the revolution axis.
[0028] In the polishing method, a distance between the revolution
axis and the rotation axis may be determined in accordance with a
dimension of an element of the polished body which is an element
substrate.
[0029] In the polishing method, the element substrate may be a
semi-conductor wafer, a glass substrate or a quartz substrate.
[0030] In the polishing apparatus, the supply passage may pass
through the rotation axis and a supply tube for supplying abrasive
agent which is disposed within the supply passage may be connected
to an abrasive agent supply source for supplying the abrasive agent
via a rotary joint.
[0031] In the polishing apparatus, the supply tube may pass through
the revolution axis.
[0032] In the polishing method, the polished body may be polished
while supplying the abrasive agent from a small hole formed in the
polishing head for holding the polishing pad.
[0033] In the polishing method, a supply tube connected to the
small hole may supply the abrasive agent from the small hole to the
polished body.
[0034] In the polishing method, the supply tube may pass through
the revolution axis.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a schematic view for explaining polishing
apparatus and method according to a preferred embodiment of the
present invention;
[0036] FIG. 2 is a schematic view showing a relation between a
polishing rate and a position in an orbital movement;
[0037] FIG. 3 is a view showing a locus of a polishing pad;
[0038] FIG. 4 is a schematic view showing a polishing apparatus
according to another embodiment of the present invention;
[0039] FIG. 5 is a schematic view showing a polishing apparatus
according to a further embodiment of the present invention;
[0040] FIG. 6 is a schematic view showing a polishing apparatus
according to a still further embodiment of the present
invention;
[0041] FIG. 7 is a schematic view showing a conventional polishing
apparatus; and
[0042] FIG. 8 is a schematic view showing another conventional
polishing apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] FIG. 1 is a schematic view for explaining polishing
apparatus and method according to a preferred embodiment of the
present invention.
[0044] The reference numeral 1 denotes a holding means for holding
a polished body 2 with a polished surface 3 thereof facing
upwardly. A polishing head 10 serves to hold a polishing pad 12
having a polishing surface 11 having an area smaller than that of
the polished surface 3 while contacting with the polished surface 3
and to rotate the polishing pad around a rotation axis 13.
[0045] The polishing head 10 is provided with a first drive means
14 for rotation, and a second drive means 16 for revolving the
polishing pad 12 around a revolution axis 15, and the revolution
axis 15 and the rotation axis 13 are positioned so that a distance
D between the revolution axis 15 and the rotation axis 13 becomes
smaller than a radius L of the polishing pad 12.
[0046] The polishing pad 12 is rotated around the axis 13 in a
direction shown by the arrow A by rotating the polishing head 10
(to which the polishing pad is attached) around the rotation axis
13. At the same time, the polishing pad 12 is revolved around the
axis 15 in a direction shown by the arrow B by rotating the
polishing head 10 around the revolution axis 15.
[0047] Such a movement of the polishing pad is referred to as
"orbital movement" hereinafter.
[0048] FIG. 2 is a graph showing a polishing sectional
configuration in the orbital movement. The ordinate indicates a
polishing rate, and the abscissa indicates a position.
[0049] The sectional configuration of the polishing rate obtained
by the polishing pad which effects the orbital movement becomes the
maximum on the revolution axis when the number of rotations is the
same as the number of revolutions, and the polishing rate is
constant from the revolution axis to a predetermined position
spaced apart from the revolution axis by a certain predetermined
distance. The predetermined distance corresponds to a distance
(L-D) obtained by subtracting the distance D (between the rotation
axis and the revolution axis) from the radius L of the polishing
pad. The polishing rate is decreased as the pad is moved away from
the predetermined position. Thus, the sectional configuration of
the polishing rate obtained by the polishing pad (polishing tool)
which effects the orbital movement shows a trapezoid symmetrical
with respect to the revolution axis. By using such a sectional
configuration, an overlapping degree or extent due to scan and
oscillation is made optimum, thereby obtaining a uniform flat
polished surface having no scanning unevenness.
[0050] By changing the axis-to-axis distance D, a length of an
upper side of the trapezoid can be changed, and, thus, the
sectional configuration can be changed. In this case, however,
although the polishing rate (height of the trapezoid) and a lower
side of the trapezoid are also changed, by making the scan and the
oscillation optimum by changing the sectional configuration
appropriately, more accurate uniformity and flatness can be
obtained.
[0051] FIG. 3 is a view showing loci of five points on the
polishing pad which effects the orbital movement.
[0052] In FIG. 3, the polishing pad 12 is rotated around a point P
representing the rotation axis. Further, the polishing pad 12 is
revolved around a point Q representing the revolution axis. In this
case, a locus of revolution of the periphery of the polishing pad
12 is shown by the line S. A direction of the rotation and a
direction of the revolution of the polishing pad 12 are opposite to
each other. In this case, a point T.sub.1 on an inner surface of
the polishing pad describes a circular locus (as shown by the
arrow) in the revolution direction. Similarly, points T.sub.2,
T.sub.3 and T.sub.4 on the periphery of the polishing pad 12
describe circular loci (as shown by the arrows) in the revolution
direction. Further, the circular loci of the points T.sub.2,
T.sub.3 and T.sub.4 contact with the revolution locus S.
[0053] In this way, any point on the polishing pad 12 effects a
circular movement as shown by the circular locus. The polishing pad
12 can polish the polished body (wafer) flatly at a circular zone
(not shown) disposed around the point Q (representing the
revolution axis) and having a radius corresponding to a distance
obtained by subtracting a distance between the points P and Q from
the radius of the polishing pad 12.
[0054] There are two kinds of polished bodies, i.e., a polished
body in which an entire surface is to be polished to obtain a
desired surface configuration, and a polished body in which only a
part of the entire surface is to be polished to obtain a desired
surface configuration. The present invention provides a polishing
method particularly suitable for the latter. Thus, in the present
invention, the polishing pad 12 is rested on a desired position on
the polished body, and the polishing is effected at that position
by using the orbital movement of the polishing pad. When a
plurality portions are polished selectively, after the polishing
pad 12 is shifted to one of the portions, the polishing is
effected, and this operation is repeated.
[0055] Further, as shown in FIG. 4, an abrasive supply tube 18
disposed within a rotation shaft (rotation axis) 13 may extend
through a revolution shaft (revolution axis) 15. As shown in FIG.
4, the supply tube 18 is connected to an abrasive supplying source
30 via a rotary joint 31. The first drive means 14 comprises a
hollow motor, and the supply tube 18 is disposed within a hollow
portion of the hollow motor. With this arrangement, since the
supply tube 18 is connected to the abrasive supplying source 30 via
the rotary joint 31, the supply tube 18 can be prevented from being
twisted by the rotation of the polishing head 10, thereby
preventing the damage of the supply tube. Further, since the supply
tube 18 extends through the revolution shaft 15, the drive means
for the polishing head can be made compact, and, accordingly, the
entire polishing apparatus can be made compact.
[0056] (First Embodiment)
[0057] FIG. 5 is a schematic view for explaining a polishing
apparatus and a polishing method according to a first embodiment of
the present invention.
[0058] A circular wafer (polished body) 2 is rested on a wafer
chuck (holding means) 1. The wafer chuck 1 can be rotated around a
center line 4 of the wafer and is supported by a support 5. The
support 5 is provided with a motor (not shown).
[0059] A polishing head 10 and associated parts are constituted as
follows. That is to say, a polishing pad 12 is attached to a platen
10a with a polishing surface thereof facing downwardly. The platen
10a is rotated around the axis 13 in a direction shown by the arrow
C by a motor (first drive means) 14. The rotation axis 13 is
defined by a hollow abrasive supply tube 18. The motor 14 and the
abrasive supply tube 18 are attached to a revolution table 17, and
the revolution table 17 is rotated around the axis 15 in a
direction shown by the arrow G by a motor (second drive means) 16.
The motor 14 is a core-less motor through which the axis passes,
i.e., a hollow motor. Abrasive is supplied from an abrasive
supplying source 30 through the supply tube 18 to a rear surface of
the polishing pad 12 and is sent toward a polishing surface 11 (of
the polishing pad) through small holes formed in the polishing pad
12 or communication foams in the polishing pad itself. A
pressurizing means 19 serves to urge the polishing pad 12 against
the wafer or to separate the polishing pad 12 (contacted with the
wafer 2) from the wafer 2.
[0060] A post 20 has a function for shifting the polishing head 10
along the upper surface of the wafer 2 and a function for
supporting the polishing head 10.
[0061] In this polishing apparatus, the rotation axis 13 and the
revolution axis 15 are positioned so that the radius L of the
polishing pad 12 becomes greater than the distance D between the
rotation axis 13 and the revolution axis 15 (L>D).
[0062] Next, a polishing method effected by using this polishing
apparatus will be explained.
[0063] First of all, the wafer 2 is rested on the wafer chuck 1
with the polished surface (on which elements such as transistors
are formed) facing upwardly and is secured to the chuck by vacuum
suction.
[0064] The polishing pad 12 is adhered to the lower surface of the
platen 10a with the polishing surface 11 thereof facing
downwardly.
[0065] Mixture of abrasive particles and dispersing medium is
loaded within the abrasive supplying source (tank) 30.
[0066] A drive control device 40 of the polishing apparatus is
driven to operate the polishing apparatus. On the basis of surface
configuration data inputted to the drive control device 40, the
wafer chuck 1 is rotated and the head 10 is shifted along the
surface of the wafer, thereby positioning the polishing pad 12 at a
position opposed to a portion (to be polished) of the wafer.
[0067] The abrasive agent is supplied onto the surface of the wafer
from the abrasive supplying source 30 through the polishing pad
12.
[0068] The platen 10a is rotated in the direction C and is revolved
in the direction G.
[0069] The polishing head 10 is lowered to urge the polishing pad
12 against the wafer, thereby effecting the polishing with
predetermined pressure.
[0070] After the polishing is continued for a predetermined time
period, the head 10 is lifted. Thereafter, if other part is desired
to be polished, the positioning of the part to be polished is
performed by rotating the wafer 1 and shifting the head along a
radial direction of the wafer, and then, the polishing is effected
by repeating the above-mentioned processes. If there is no part to
be further polished, the rotation, revolution and supply of the
abrasive are stopped, thereby finishing the polishing
operation.
[0071] (Second Embodiment)
[0072] FIG. 6 shows a general purpose polishing apparatus according
to a second embodiment of the present invention.
[0073] The second embodiment differs from the first embodiment in
the point that there is provided a variable means for changing the
distance D between the rotation axis 13 and the revolution axis 15
to polish the wafer more precisely in accordance with the kind of
wafers. Further, a detection head for detecting the surface
configuration to effect the positioning correctly in the polishing
operation may be provided for shifting movement in a radial
direction of the wafer 1.
[0074] The platen 10a, motor 14 and supply tube 18 are attached to
a collapsible arm (variable means) 22 having a joint 21. The joint
21 can be operated manually or by a drive means (not shown) to
adjust the distance D. A limiter may be provided so that the
distance D does not exceed the radius L of the polishing pad 12 or
the platen 10a when the distance D is determined.
[0075] The detection head 23, if provided, comprises a photo-sensor
and is supported by a head guide 24 for shifting movement in a
radial direction of the wafer chuck 1. The guide 24 is secured to a
post 25. A range of the radial shifting movement of the detection
head 23 is defined between a center line 4 of the wafer chuck and a
radial end of the wafer chuck. The drive control device 40 judges
where the detected surface condition is situated on the wafer on
the basis of the rotation amount and the radial shifting amount of
the wafer. After the correction polishing is effected by the
polishing head 10, the surface configuration of the polished
portion is detected again by the detection head 23. If it is judged
that such configuration is not desired, the same portion is
polished again.
[0076] The other constructions are the same as those in the first
embodiment.
[0077] Next, a polishing method effected by using this polishing
apparatus will be explained.
[0078] First of all, the wafer 2 is rested on the wafer chuck 1
with the polished surface (on which elements such as transistors
are formed) facing upwardly and is secured to the chuck by vacuum
suction.
[0079] In accordance with sizes of IC chips or sizes of
semi-conductor elements formed on the wafer 2 to be polished, a
size of the polishing pad 12 is selected. For example, regarding an
8-inch wafer, when the size of a microprocessor chip to be formed
is 10 mm.times.10 mm, a circular or rectangular polyurethane pad
having a dimension greater than the size of the chip from by
several times to by one-several numbers time may be used as the
polishing pad 12. The polishing pad 12 is adhered to the lower
surface of the platen 10a with the polishing surface thereof facing
downwardly.
[0080] The distance D is a desired value which does not exceed the
radius L of the pad by adjusting the joint 21.
[0081] Mixture of abrasive particles and dispersing medium is
loaded within the abrasive supplying source (tank) 30.
[0082] The drive control device 40 of the polishing apparatus is
driven to operate the polishing apparatus.
[0083] In the illustrated embodiment, the surface configuration of
the wafer 2 is detected by using the detection head 23. On the
basis of the data regarding the surface configuration inputted from
the detection head 23 to the drive control device 40, the wafer
chuck 1 is rotated and the head 10 is shifted along the surface of
the wafer, thereby positioning the polishing pad 12 at a position
opposed to a portion (to be polished) of the wafer.
[0084] The abrasive agent is supplied onto the surface of the wafer
from the abrasive supplying source 30 through the polishing pad
12.
[0085] The platen 10a is rotated in the direction C and is revolved
in the direction G.
[0086] The ration between the number of rotations and the number of
revolutions is preferably 1 or one-several numbers time or several
times to obtain a good result.
[0087] The polishing head 10 is lowered to urge the polishing pad
12 against the wafer, thereby effecting the polishing with
predetermined pressure.
[0088] After the polishing is continued for a predetermined time
period, the head 10 is lifted. Thereafter, if other part is desired
to be polished, the positioning of the part to be polished is
performed by rotating the wafer 1 and shifting the head along a
radial direction of the wafer, and then, the polishing is effected
by repeating the above-mentioned processes. If there is no part to
be further polished, the surface configuration is detected again by
the detection head 23. In this case, if the detected surface
configuration is desirable, the rotation, revolution and supply of
the abrasive are stopped, thereby finishing the correction
polishing operation. According to the illustrated embodiment, since
the distance between the rotation axis and the revolution axis can
be changed, even any element substrates having different IC chip
size, transistor size or wiring rule, the substrate can be polished
flatly with high accuracy along undulation of the element
substrate.
[0089] According to the present invention, the configuration of the
desired part of the polished body can selectively or preferentially
be correction-polished with high accuracy.
* * * * *