U.S. patent application number 09/770743 was filed with the patent office on 2001-10-11 for polishing apparatus and polishing method, and method of manufacturing semiconductor device and method of manufacturing thin film magnetic head.
Invention is credited to Horinaka, Takehiro, Iijima, Atsushi, Kubota, Toshio, Sasaki, Yoshitaka.
Application Number | 20010029158 09/770743 |
Document ID | / |
Family ID | 26521281 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010029158 |
Kind Code |
A1 |
Sasaki, Yoshitaka ; et
al. |
October 11, 2001 |
Polishing apparatus and polishing method, and method of
manufacturing semiconductor device and method of manufacturing thin
film magnetic head
Abstract
A polishing apparatus comprises a plurality of (three, for
example) polishing portions and a cleaning portion. First, roughing
is performed in a first polishing portion by a platen made of a
hard grinder. The polishing surface of the platen is hard so that
the wafer on the polishing surface exhibits no pattern dependence.
Next, scratches and polishing distortion slightly generated on the
wafer in the platen are removed (medium polishing) by a hard
abrasive pad with a single-layered structure in a second polishing
portion. Further, finishing is performed in a third polishing
portion by an abrasive pad with a two-layered structure. At last,
the contamination left by the micro scratches or slurry generated
in the prior process is completely cleaned by a cleaning pad in the
cleaning portion.
Inventors: |
Sasaki, Yoshitaka; (Tokyo,
JP) ; Iijima, Atsushi; (Tokyo, JP) ; Kubota,
Toshio; (Tokyo, JP) ; Horinaka, Takehiro;
(Tokyo, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. Box 19928
Alexandria
VA
22320
US
|
Family ID: |
26521281 |
Appl. No.: |
09/770743 |
Filed: |
January 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09770743 |
Jan 26, 2001 |
|
|
|
09359807 |
Jul 26, 1999 |
|
|
|
Current U.S.
Class: |
451/66 ;
451/288 |
Current CPC
Class: |
B24B 37/14 20130101;
B24B 37/245 20130101; B24B 37/345 20130101 |
Class at
Publication: |
451/66 ;
451/288 |
International
Class: |
B24B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 30, 1998 |
JP |
10-216176 |
Claims
What is claimed is:
1. A polishing apparatus for polishing and planarizing a subject of
polishing with a base having at least one layer, comprising: a
pedestal; and a plurality of polishing portions each having a
rotatable platen, provided on the pedestal and being moveable
relative to the pedestal, for performing polishing of different
degrees on at least one layer of the one subject of polishing,
wherein the rotatable platen of the plurality of polishing portions
is formed with a resin defined by a base having a thickness with
essentially no distortion.
2. The polishing apparatus according to claim 1, wherein the
rotatable platen has a thickness of about 0.5 to about 5.0 mm.
3. The polishing apparatus according to claim 2, wherein the
rotatable platen has a ring shape and a thickness of about 1.0 mm
or less.
4. The polishing apparatus according to claim 2, wherein the
rotatable platen has a ring shape.
5. The polishing apparatus according to claim 1, wherein the resin
includes diamond grains.
6. The polishing apparatus according to claim 1, wherein the resin
is comprised of at least one of a phenolic resin and an epoxy
resin.
7. The polishing apparatus according to claim 1, wherein the resin
is a glass resin.
8. The polishing apparatus according to claim 1, wherein the resin
is polyurethane foam.
9. The polishing apparatus according to claim 1, wherein the
rotatable platen has a ring shape and a thickness of about 1.0 mm
or less.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This is a Continuation-in-Part of Application Ser. No.
09/359,807, filed Jul. 26, 1999. The entire disclosure of the prior
application is hereby incorporated by reference herein in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The invention relates to a polishing apparatus and a
polishing method for planarization of a thin film magnetic head, a
semiconductor integrated circuit and so on, and a method of
manufacturing a semiconductor device and a method of manufacturing
a thin film magnetic head.
[0004] 2. Description of Related Art
[0005] In a manufacturing process of a semiconductor integrated
circuit using silicon or the like, microfabrication of the metallic
wiring is required in order to scale down a device and to improve
performance of elements. Specifically, it is necessary to form the
pattern with a submicron thickness and to laminate such patterns to
form a multi-layer.
[0006] In such a multi level interconnect structure, interlayer
insulating films made of silicon oxide film or other films are
provided between each two metallic wiring layers. In the structure,
the interlayer insulating films have steps about 0.5 to 0.7 .mu.m
deep because of the metallic wiring. Accordingly, it is necessary
to planarize an interlayer insulating film before forming another
metallic wiring thereon.
[0007] There is a similar problem in a manufacturing process of a
thin film magnetic head. In recent years, performance improvement
in thin film magnetic heads has been sought in accordance with
improvement in surface recording density of a hard disk drive. A
composite thin film magnetic head comprising a recording head with
an inductive-type magnetic transducer and a reproducing head with a
magnetoresistive element is widely used as a thin film magnetic
head. There are several types of magnetoresistive elements: one is
an AMR element using Anisotropic Magneto Resistive effect and
another is a GMR element using Giant Magneto Resistive effect.
[0008] In such a composite thin film magnetic head, it is necessary
to improve the performance both of the recording head and of the
reproducing head. This has been achieved by microfabrication of
tracks in addition to selecting materials suitable for each part of
the composite thin film magnetic head.
[0009] Specifically, in order to increase the recording density of
the recording head, microfabrication of the magnetic pole portion
is required. Therefore, submicron processing using a semiconductor
processing technique is applied. On the other hand, in order to
write information accurately with the continued advance of
microfabrication, it is necessary for at least one of the magnetic
pole to be about 2.5 to 3.5 .mu.m thick. Planarizarion of the
underlying layer has been required for forming such a magnetic
pole.
[0010] Similarly, in the reproducing head, it is necessary to form
tracks with submicron widths in a magnetoresistive film. Usually,
the magnetoresistive film is formed on a thick shield magnetic film
with a thickness of about 2.0 to 3.0 .mu.m with a shield gap layer
in between. Accordingly, planarization of the underlying layer has
been also required for forming a magnetoresistive film.
[0011] The performance of the recording head also depends on the
distance from an air bearing surface (ABS), that is, a throat
height. The throat height is determined by the amount of polishing
at the time of processing the ABS. Further, the performance of the
reproducing head also depends on the distance from the ABS, that
is, an MR height. The MR height is also determined by the amount of
polishing at the time of processing the ABS.
[0012] As described, the microfabrication technology and the
planarization method have become the most important process
techniques in accordance with the performance improvement in the
semiconductor integrated circuit and the thin film magnetic head.
The process of planarization is precisely performed provided the
microfabrication process is accurately performed. Therefore, it is
necessary to perform the planarization process accurately in order
to improve the performance of the semiconductor device or the thin
film head device.
[0013] Examples of planarization methods are CMP (Chemical
Mechanical Polishing) using slurry (abrasives) and MP (Mechanical
Polishing) for polishing by a platen in which fine diamond grains
are scatteringly buried using oil or the like as lubricant.
[0014] CMP, however, has several problems since it has a polishing
characteristic that the abrasive pad follows the wafer pattern. On
the other hand, MP has a problem that scratches are easily formed
on the surface of the wafer. In order to suppress the scratches,
diamond grains with smaller diameters may be used. However, this
may cause another problem that the polishing speed decreases.
[0015] The polishing apparatus using these methods has one platen
and polishes the surface of the wafer. However, some apparatuses
have two platens (AVANTE472; product of IPEC PLANER, for example).
This type of polishing apparatus uses an abrasive pad with
two-layered structure using relatively soft materials (IC1000, and
suba 400 or 800; product of RODRAL Nitta, for example) for one of
the platens, and a cleaning pad having a soft brush with long pile
for the other platen. The apparatus removes the slurry attached by
the cleaning pad after polishing once using the abrasive pad.
Therefore, the apparatus also has several problems in controlling
the amount of polishing because of the pattern dependence in the
wafer, like the polishing apparatus with one platen.
[0016] In the followings, the specific problems when performing
planarization using these polishing apparatuses will be described.
First, the configurations of a semiconductor integrated circuit and
a thin film magnetic head to which the planarization process is
applied will be described.
[0017] FIG. 12 shows CMOS (Complementary Metal Oxide Semiconductor)
circuit with a five level interconnect structure as an example of
the semiconductor integrated circuit.
[0018] In the CMOS integrated circuit, an n-type well region 100a
is formed in a p-type substrate 100 made of such as silicon, for
example. A LOCOS (Local Oxidation of Silicon) film 101 as an
element isolation film is formed on the surface of a substrate 100.
An n-type MOS transistor 107 comprises a pair of n-type impurity
regions 103 and 104 as a source or a drain and a gate electrode 106
formed on the surface of the substrate 100 between the impurity
regions 103 and 104 with a gate oxide film 105 in between. A p-type
MOS transistor 107a comprises p-type impurity regions 103a and 104a
formed in the well region 100a and a gate electrode 106 formed on
the surface of the well region 100a between the impurity regions
103a and 104a with the gate oxide film 105 in between. The gate
electrode 106 is made of polycrystal silicon film to which
impurities are added, and has gate side walls (side walls) 106a on
its side surfaces. The first to fifth wiring layers 109a to 109e
made of copper (Cu) or aluminium-copper alloy (AlCu) are stacked on
the MOS transistors 107 and 107a with LTO (Low Temperature
Oxidation) film 0.2 .mu.m thick, for example, and interlayer
insulating films 108a to 108f, each 0.8 .mu.m thick and made of
BPSG (Boro-Phospho-Silicate Glass), in between. The wiring layers
109a to 109e are electrically connected through via-plug 110 made
of tungsten (W) or the like provided in the interlayer insulating
films 108a to 108e.
[0019] In the manufacturing process of such CMOS circuit,
planarization is performed to polish protrusions of each of the
interlayer insulating films when each of the interlayer insulating
films 108a to 108e is formed after the metallic wiring layers 109a
to 109e are formed respectively. Planarization is also performed to
remove metal attached to the surface of the substrate other than a
contact hole after the contact hole (contact hole or bear hole) is
formed on the interlayer insulating films 108a to 108e and then
metal such as tungsten is deposited on the surface of the substrate
including the contact hole by CVD (Chemical Vapor Deposition).
[0020] FIGS. 13A and 13B show the cross sectional configuration of
a composite thin film magnetic head as an example of a thin film
magnetic head of the related art. FIG. 13A shows a cross section
vertical to the track surface and FIG. 13B shows a cross section
parallel to the track surface of the magnetic pole portion. This
magnetic head 200 comprises a reproducing head 200A and a recording
head 200B.
[0021] The reproducing head 200A comprises a magnetoresistive film
205 made of permalloy (NiFe alloy), for example, formed on a
substrate 201 made of altic (alumina titanium carbide;
Al.sub.2O.sub.3-TiC), for example, with an undercoating layer 202
made of alumina (aluminum oxide; Al.sub.2O.sub.3), for example, a
bottom shield layer 203 made of ferrous aluminum silicide (FeAlSi),
for example, and a shield gap layer 204 made of aluminum oxide
(Al.sub.2O.sub.3, referred to as alumina in the followings), for
example, in between in this order. A lead electrode layer 205a is
also formed on the shield gap layer 204 and is electrically
connected to the magnetoresistive film 205. A shield gap layer 106
made of alumina, for example, is stacked on the magnetoresistive
film 205 and the lead electrode layer 205a. In other words, the
magnetoresistive film 205 and the lead electrode layer 205a are
buried between the shield gap layers 204 and 206.
[0022] The recording head 200B comprises a top pole 209 formed on
the reproducing head 200A with a bottom pole 207 which also works
as a top shield layer for the magnetoresistive film 205 (referred
to as bottom pole in the followings) and a write gap layer 208 in
between. The top pole 209 is divided into two parts: a pole tip
209a which determines the track width and a top magnetic layer 209b
which works as a yoke. An insulating layer 210 made of alumina is
formed on the bottom pole 208. The surface of the insulating layer
210 is planarized to form the same surface as the surface of the
pole tip 209a. Thin film coils 211 and 212 are stacked on the
insulating layer 210, and are covered with insulating layers 213
and 214. The top magnetic layer 209b is formed on the pole tip 209a
and the insulating layers 213 and 214. The top magnetic layer 209b
is covered with an overcoat layer 215. In the recording head 200B,
the bottom pole 207 facing the top pole 209 has a trim structure in
which part of the surface is processed to be protruded.
[0023] In the reproducing head 200A of such a composite thin film
magnetic head, the characteristic of the magnetoresistive element
largely depends on the surface of the bottom shield layer 203.
Therefore, in general, the bottom shield layer 203 is planarized
before these elements are formed. Similarly, the surface of the
bottom pole 208 is planarized before the write gap layer 208 is
formed in order to improve the performance of the recording head
200B. Further, in the recording head 200B, the top pole 209 is
divided into the top pole tip 209a and the top magnetic layer 209b
in order to form a narrow track. The insulating layer 210 is
planarized after the pole tip 209a is formed.
[0024] In most of the thin film magnetic heads, magnetic materials
and insulating materials, metallic materials for coils or other
materials are exposed to the surface by planarization. As a result,
the planarization process using the polishing apparatus of the
related art has serious problems such as flatness, scratches, and
recesses between the insulating film and the metallic layer, since
magnetic materials and insulating materials or metallic materials
are polished at one time.
[0025] FIG. 14 specifically shows the configuration of a platen of
a polishing portion and a wafer holder (head portion) as an example
of a CMP apparatus of the related art. The CMP apparatus comprises
an abrasive pad (abrasive cloth) 301 pasted on a platen 300. The
apparatus planarizes the surface of the wafer through polishing the
uneven surface of the wafer by pouring slurry with a specific
diameter of grains in between a wafer holder 302 and the abrasive
pad 301 while the platen 300 and the wafer holder 302 to which a
wafer is attached are rotated.
[0026] In such a polishing apparatus, materials with a large
frictional drag or materials with a small frictional drag is used
as the abrasive pad 301 depending on the intended polishing speed
or the amount of polishing. Two-layered pad in which a hard pad and
a soft pad are laminated or a single-layered pad using a hard pad
or a soft material is used as the abrasive pad 301 depending on its
usage. Further, planarization of the wafer is performed by changing
the rotation frequency of the wafer holder 302 and the platen 300
or reversing the direction of rotation. Further, the kind of
materials of slurry or the diameter of the grains are taken into
consideration in order to ensure uniformity in the amount of
polishing, the polishing speed, and also the amount of polishing in
the wafer.
[0027] With such a method, however, there has been a limit in
precision of polishing. Especially the pattern shape in the wafer
has been an important factor to determine the uniformity in
flatness, as specifically described in the followings.
[0028] First, problems in forming the metallic wiring in a
semiconductor integrated circuit of the related art will be
described with reference to FIGS. 15A and 15B.
[0029] FIG. 15A shows a state in which an interlayer insulating
film 402 about 2 mm thick made of silicon oxide film (SiO.sub.2) is
formed on a plurality of metallic wiring patterns 401 with a film
thickness of 0.7 .mu.m which are formed on a field oxide film 400
formed on a silicon substrate. The interlayer insulating film 402
has protrusions 402a over a region where the minute metallic wiring
patterns 401 are aggregated. FIG. 15B shows a state after
planarizing the surface of the interlayer insulating film 402 by
the CMP apparatus shown in FIG. 12.
[0030] As seen from FIGS. 15A and 15B, when a wafer including part
in which the minute metallic wiring patterns 401 are aggregated
(dense region) and other part in which the metallic wiring patterns
401 are not aggregated (empty region) is planarized by the CMP
apparatus, the region of the protrusions 402a where the metallic
wiring patterns 401 are aggregated is completely planarized.
However, the areas between two dense regions where the wiring
metallic patterns 401 are densely formed do not have high
flatness.
[0031] In other words, in such a planarization process, the state
after planarization varies depending on the metallic wiring
patterns in the wafer or the arrangement of the regions where the
patterns are aggregated. In general, when the polishing process is
performed over the dense region where the minute patterns are
densely formed and over an isolated pattern of a minute pattern or
a large pattern, the area of contact between the abrasive pad and
the protrusions over the patterns in the wafer differs, and thus
the polishing speed or the state after planarization differs. The
polishing speed of polishing over the isolated minute pattern is
greater than that of polishing over the aggregated large patterns.
As a result, the film thickness of the interlayer insulating film
over the former part becomes different from other parts so that
over-etching is required in accordance with the film thickness of
the thickest interlayer insulating film at the time of forming
contact holes and others in the interlayer insulating film.
[0032] When minute contact holes of 0.5 .mu.m, 0.3 .mu.m, or 0.25
.mu.m, in diameter for example, are formed by dry etching such as
RIE (Reactive Ion Etching), a large amount of over-etching is
required. As a result, ohmic contact resistance between the contact
holes or the like and the electrode wiring becomes large and thus
the performance of many of the device characteristic deteriorates,
which ultimately results in decreasing the yields. Further, as
mentioned above, when the polishing process by CMP is performed
over the region including part in which lots of minute metallic
patterns are aggregated and other part in which metallic wiring
patterns are not aggregated, the part in which the metallic wiring
patterns are aggregated is precisely planarized, while the part
between two regions of the aggregated wiring patterns does not have
high flatness. This becomes worse as the number of the wiring
layers increases to four, five or more.
[0033] As described, the CMP apparatus of the related art has a
problem that the CMP apparatus can achieve an excellent flatness
locally but cannot attain sufficient flatness over a wide area. As
a result, in the manufacturing process of the semiconductor
integrated circuit of the related art, the wiring layer provided on
the region with low flatness have breaks or failures caused by
electro-migration if the width of the metallic wiring pattern is
small.
[0034] Next, specific problems in the manufacturing process of a
thin film magnetic head will be described with reference to FIGS.
16A to 16C. The figures show the thin film magnetic head viewed
from the ABS side. As shown in FIG. 16A, an insulating layer 501
about 3 to 5 .mu.m thick made of alumina is deposited on a
substrate 500 made of altic by sputtering, for example. Next, a
bottom shield layer 502 about 2 to 3 .mu.m thick for the
reproducing head made of a magnetic material such as permalloy
(NiFe) is formed on the insulating layer 501 by plating, for
example. Then an insulating layer 503 about 3 to 4 .mu.m thick made
of alumina is formed on the bottom shield layer 502. The insulating
layer 503 has protrusions 503a over the bottom shield layer
502.
[0035] FIG. 16B shows a state after the surface of the insulating
layer 503 is planarized by a polishing apparatus. In such a thin
film magnetic head, it is necessary to polish the surface of the
insulating layer 503 to reach the bottom shield layer 502 so as to
make the bottom shield layer 502 exposed in the surface of the
insulating layer 503. As a result, there are steps between the
insulating layer 503 and the bottom shield layer 502 so that either
the insulating layer 503 or the bottom shield layer 502 has a
recessed structure which partially includes recesses. The sizes of
the recesses in such a case reaches 0.15 to 0.3 .mu.m, sometimes
0.4 .mu.m or more.
[0036] As shown in FIG. 16C, after a bottom shield gap film 504, a
magnetoresistive film 505 and its lead electrode layer 506, a top
shield gap film 507 and a top shield-cum-bottom pole 508 are formed
in a thickness of about 2 to 4 .mu.m, another insulating layer 509
made of alumina is formed in a thickness of 3 to 5 .mu.m, and then
the surface of the insulating layer 509 is polished by the
polishing apparatus. The recesses are also formed at this time.
Further, after a write gap film 510 is formed in a thickness of 0.2
to 0.3 .mu.m, a pole tip 511 is formed in a thickness of 2 to 3
.mu.m. Again, an insulating layer 512 is formed in a thickness of 3
to 4 .mu.m and then polished. At this time, the recesses of 0.2 to
0.4 .mu.m are also formed. The manufacturing process of a thin film
magnetic head is completed after forming a thin film coil (not
shown in figure), a top magnetic layer (top pole) 513, an overcoat
layer (not shown in figure) and so on.
[0037] As described, the manufacturing process of a thin film
magnetic head is a little different from that of a semiconductor
integrated circuit mentioned above. That is, the material to be
polished is different and, in general, a plurality of layers made
of materials with different hardness are polished in a thin film
magnetic head. For example, the structure in which an insulating
layer made of alumina and a thin film coil or the like made of
permalloy (NiFe) or copper (Cu) are exposed together in the surface
of the wafer. Accordingly, it is necessary to complete the CMP
process taking the materials and the polishing speed into
consideration. It is extremely difficult to control uniformity of
the amount of polishing of the whole wafer since the polishing
speed varies because of the pattern dependence.
[0038] Further, excellent uniformity in thickness of the bottom
shield layer, the top shield layer, the pole tip and so on in the
wafer after being polished is required, in addition to controlling
the amount of polishing by CMP. The uniformity in thickness largely
contributes to the performance of the thin film magnetic head so
that precise control of the film thickness is required.
[0039] With the polishing apparatus of the related art, however, it
has not been possible to achieve a CMP process, in which the film
thickness of the insulating layer made of such as alumina and the
magnetic layer (shield magnetic film or recording pole) made of
such as permalloy (NiFe) is precisely controlled. The reason is
because it is extremely difficult to control the polishing speed of
the substances with different hardness such as the insulating layer
made of alumina and metal such as permalloy, as described, and thus
recesses are formed between the insulating layer and the top or
bottom shield layers when the bottom shield layer, the top shield
layer and the pole tip are polished. This has been a main factor
for suppressing the performance of the thin film magnetic head.
SUMMARY OF THE INVENTION
[0040] The invention is designed to overcome foregoing problems. An
object of the invention is to provide a polishing apparatus and a
polishing method which can perform a planarization process with
high precision in accordance with a scale-down of a device such as
a semiconductor device or a thin film magnetic head.
[0041] Another object of the invention is to provide a
manufacturing method of a semiconductor device for performing a
planarization process with high precision in accordance with a
scale-down.
[0042] Still another object of the invention is to provide a
manufacturing method of a thin film magnetic head for performing a
planarization process with high precision in accordance with a
scale-down.
[0043] A polishing apparatus of the invention comprises a plurality
of polishing portions for performing polishing processing of
different degrees on one subject of polishing.
[0044] In the polishing apparatus of the invention, it is desired
that the polishing portions include at least a first polishing
portion for performing roughing on the subject of polishing and a
second polishing portion for performing finishing on the subject
which has been roughed by the first polishing portion.
[0045] In the polishing apparatus, roughing is performed on the
subject of polishing in a first polishing portion, and then, in a
second polishing portion, finishing is performed on the subject of
polishing which has been roughed.
[0046] Further, the polishing apparatus of the invention may
further include a third polishing portion comprising at least one
polishing portion for performing medium polishing on the subject
which has been roughed by the first polishing portion, the third
polishing portion provided between the first polishing portion and
the second polishing portion.
[0047] The polishing apparatus of the invention may have a
configuration in which each of the polishing portions comprises a
rotatable platen, and an abrasive pad with a laminated structure of
a plurality of layers which have different hardness is pasted on at
least one of the platens.
[0048] The polishing apparatus of the invention may have a
configuration in which the abrasive pad has a two-layered structure
with one layer for polishing a subject being formed of a hard resin
and the other layer being formed of a softer material than the one
layer. The one layer may be formed of polyurethane foam.
[0049] The polishing apparatus of the invention may have a
configuration in which an abrasive pad with a single-layered
structure is pasted on at least one of the other platens.
[0050] The polishing apparatus of the invention may have a
configuration in which at least one of the platens includes a
grinder on at least part of the polishing surface. Specifically,
the grinder may take a disk-like shape or a ring shape and have a
thickness of about 0.5 mm to about 5.0 mm. The grinder may include
diamond grains and the grinder including diamonds may be formed
with resin being a base. Examples of the resin as a base include a
phenolic resin, an epoxy resin and a glass resin. Generally, a
grinder requires careful handling because it may be as thin as 0.01
mm or less. The grinder of the preferred embodiment has a thickness
of about 0.5 mm to about 5.0 mm and a certain hardness.
Accordingly, the grinder is easier to handle or replace.
Furthermore, since the grinder preferably has a thickness of about
0.5 mm to about 5.0 mm, diamond grains my be buried within the
thickness in a stable manner to promote polishing.
[0051] In the polishing apparatus of the invention, the grinder may
be formed of a hard resin. As the resin, a polyurethane foam is
used, for example.
[0052] In the polishing apparatus of the invention, roughing may be
performed on the subject of polishing using the grinder in the
first polishing portion. Further, medium polishing may be performed
on the subject of polishing in the third polishing portion using a
grinder with smaller roughness than that of the first polishing
portion, and then finishing may be performed on the subject of
polishing in the second polishing portion using a grinder with
smaller roughness than that of the third polishing portion.
Otherwise, medium polishing may be performed on the subject of
polishing in the third polishing portion using a grinder with
smaller roughness than that of the first polishing portion, and
then finishing may be performed on the subject of polishing in the
second polishing portion using an abrasive pad with smaller
roughness than that of the third polishing portion. Alternatively,
medium polishing may be performed on the subject of polishing in
the third polishing portion using an abrasive pad with smaller
roughness than that of the first polishing portion, and then
finishing may be performed on the subject of polishing in the
second polishing portion using an abrasive pad with smaller
roughness than that of the third polishing portion.
[0053] In the polishing apparatus of the invention, the abrasive
pad of the second polishing portion may be an abrasive pad with the
laminated structure described above.
[0054] Further, in the polishing apparatus of the invention,
roughing may be performed on the subject of polishing in the first
polishing portion using the above-mentioned grinder, and then
finishing may be performed on the subject of polishing in the
second polishing portion using an abrasive pad with smaller
roughness than that of the first polishing portion.
[0055] In the polishing apparatus of the invention, roughing may be
performed on the subject of polishing in the first polishing
portion using the above-polishing in the second polishing portion
using an abrasive pad with smaller roughness than that of the first
polishing portion. The abrasive pad of the second polishing portion
may be the polishing pad with the above mentioned laminated
structure.
[0056] In the polishing apparatus of the invention, slurry may be
used together with the abrasive pad in the second polishing
portion. The slurry including alumina grains is used at this
time.
[0057] The polishing apparatus of the invention may further include
a cleaning portion for performing cleaning on the subject of
polishing which has been finished in the second polishing portion.
The cleaning portion may comprise a cleaning pad made of a soft
brush.
[0058] In the polishing apparatus of the invention, for example, a
wafer for a semiconductor integrated circuit or a wafer for a thin
film magnetic head is used as the subject of polishing.
[0059] In the polishing apparatus of the invention, each of the
platens of the respective polishing portions is stored in a
pedestal and processing may be performed on the subject of
polishing in order in the polishing portions.
[0060] A polishing method of the invention is for polishing and
planarizing a subject of polishing and includes at least a first
polishing step of performing roughing on the subject of polishing
and a second polishing step of performing finishing after the first
polishing step on the subject of polishing which has been
roughed.
[0061] The polishing method of the invention may further include a
third polishing step including at least one polishing step for
performing medium polishing before the second polishing step on the
subject of polishing which has been roughed in the first polishing
step.
[0062] In the polishing method of the invention, the polishing
steps may be performed in a plurality of polishing portions
included in one pedestal.
[0063] The method of manufacturing a semiconductor device of the
invention includes a planarizing step for polishing and planarizing
a wafer for a semiconductor integrated circuit, wherein the
planarizing step is performed using the polishing apparatus of the
invention. A polishing surface may be a surface of an interlayer
insulating film formed on a metallic wiring layer having aggregated
or isolated patterns provided on a semiconductor wafer, for
example.
[0064] The method of manufacturing a thin film magnetic head of the
invention includes a planarizing step for polishing and planarizing
a thin film magnetic head, wherein the planarizing step is
performed using the polishing apparatus of the invention. A
polishing surface may be a surface of an insulating layer formed to
cover one of two shield layers which sandwich a magnetoresistive
element included in a reproducing head. The polishing surface may
also be a surface of an insulating layer formed to cover a pole tip
of a recording head, the recording head comprising a magnetic pole
which is divided into the pole tip and a magnetic layer.
[0065] Other and further objects, features and advantages of the
invention will appear more fully from the following
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] FIG. 1 is a perspective view showing a configuration of a
polishing apparatus according to a first embodiment of the
invention.
[0067] FIG. 2 is a figure showing a cross sectional configuration
of the polishing portion taken along the line II-II in FIG. 1.
[0068] FIG. 3 is a cross section showing a configuration of an
abrasive pad in the polishing apparatus shown in FIG. 1.
[0069] FIG. 4 is a perspective view showing a configuration of the
polishing apparatus according to a second embodiment of the
invention.
[0070] FIGS. 5A and 5B are cross sections for describing a
planarization process of a semiconductor integrated circuit by the
polishing apparatus of the invention.
[0071] FIGS. 6A, 6B and 6C are cross sections for describing a
planarization process of a thin film magnetic head by the polishing
apparatus of the invention.
[0072] FIG. 7 is a characteristic diagram for describing the
polishing result using the polishing apparatus of the related
art.
[0073] FIGS. 8A and 8B are characteristic diagrams for describing
the polishing result using the polishing apparatus of the
invention; FIG. 8A shows the result of polishing alumina and FIG.
8B shows the result of polishing permalloy.
[0074] FIG. 9 is a plan view for describing the measuring point of
the wafer in the characteristic diagrams shown in FIGS. 8A and
8B.
[0075] FIG. 10 is a perspective view for describing an example of
grinder used in the polishing apparatus of the invention.
[0076] FIG. 11 is a plan view for describing a schematic
configuration of the apparatus according to still another
embodiment of the invention.
[0077] FIG. 12 is a cross section of a CMOS circuit as an example
to which a planarization process by the polishing apparatus is
applied.
[0078] FIG. 13A is a cross section of a thin film magnetic head as
another example to which the planarization process by the polishing
apparatus is applied.
[0079] FIG. 13B is a cross section of the thin film magnetic head
shown in FIG. 13A viewed from the ABS side.
[0080] FIG. 14 is a perspective view showing a configuration of a
polishing apparatus of the related art.
[0081] FIGS. 15A and 15B are cross sections for describing problems
in using the polishing apparatus of the related art in a
planarization process of a semiconductor integrated circuit.
[0082] FIGS. 16A, 16B and 16C are cross sections for describing
problems in using the polishing apparatus of the related art in a
planarization process of a thin film magnetic head.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0083] Preferred embodiments of the invention will be described in
the followings with reference to corresponding figures.
[0084] [First Embodiment]
[0085] FIG. 1 shows a configuration of a polishing apparatus 1
according to a first embodiment of the invention. The polishing
apparatus 1 is for polishing a subject of polishing such as the
surfaces of wafers and comprises a pedestal 10. A plurality of
(three, for example, in this embodiment) polishing portions 11A to
11C, and a cleaning portion 11D are provided on the pedestal 10.
The polishing portions 11A to 11C and the cleaning portion 11D
comprise platens 12a to 12d respectively. The platens 12a to 12d
are placed on the surface of the pedestal 10 in a rotatable state.
The platens 12a to 12d are coupled to a rotating device (not shown
in figure) provided under the pedestal 10 through openings (not
shown in figure) provided in the pedestal 10. The platens 12a to
12d are made to rotate with a predetermined speed in a
counterclockwise direction when viewed from the above.
[0086] Four wafer holders (heads) 14 are placed on the pedestal 10
facing the platens 12a to 12d. The wafer holders 14 comprise a
holder 14a (not shown in FIG. 1, see FIG. 2) for holding wafers.
The wafer holder 14a is also made to rotate with a predetermined
speed in a clockwise direction when viewed from the above by a
spindle motor (not shown in figure) around a rotating shaft 14b.
The surfaces of the platens 12a to 12d in the polishing portions
11A to 11C and the cleaning portion 11D respectively have different
roughness and hardness from one another. The wafer to be polished,
together with the wafer holder 14a, is moved to a position facing
the platens 12a to 12d of the polishing portions 11A to 11C and the
cleaning portion 11D in this order to be polished and cleaned to a
different degree.
[0087] At least part of the polishing surface of the platen 12a, or
the whole surface, is composed of a grinder. As the grinder, resin
such as phenol resin is used as a base to which diamond grains with
the diameter being 1,000th to 3000th, 5,000th or 10,000th are
scatteringly fixed. The grinder takes a round or disk-like shape
and has a thickness of about 0.5 mm to about 5.0 mm and a cerain
hardness, for example. The grinder may be a diamond grinder
(vitrified) in which a glass resin is used as a base. It may be
formed only of hard resin such as porous polyurethane foam, phenol
resin or epoxy resin without using diamond grains.
[0088] FIG. 2 shows an example of a cross sectional configuration
of the polishing portion 11A shown in FIG. 1 taken along the line
II-II. In FIG. 2, the holder 14a of the wafer holders 14 is formed
of porous chuck. A wafer W is adsorbed and held by the holder 14a
through the cavity 14c provided in the wafer holder 14 being
evacuated in the direction shown by an arrow a in the figure. In
the polishing portion 11A, a lubricant 16 is supplied from a nozzle
15. Examples of the lubricants are pure water, oil, isopropyl
alcohol, alumina slurry, silica slurry and the like.
[0089] In the embodiment, first, polishing (roughing) of the wafer
W is performed by the platen 12a in the polishing portion 11A while
supplying lubricator 16 from the nozzle 15. Thus the protrusions of
the insulating film covering lots of different patterns in the
wafer such as aggregated minute wiring patterns, a large pattern or
an isolated pattern are made to be removed flat. In the polishing
portion 11A, the platen 12a is formed of a grinder and thus has a
hard polishing surface. As a result, there are scratches being
slightly generated, but the polishing surface exhibits no pattern
dependence. The polishing portion 11A corresponds to the "first
polishing portion" of the invention.
[0090] The abrasive pad 13b with a single-layered structure made
of, for example, a hard polyurethane form is pasted on the surface
of the platen 12b in the polishing portion 11B. Polishing is
performed by the abrasive pad 13b using an abrasive liquid supplied
from a nozzle (not shown in figure). Examples of the slurry
included in the abrasive liquid are alumina, silica and a mixture
of both. The polishing portion 11B performs the medium polishing
(that is, polishing with a degree between the first roughing and
the last finishing) through removing the scratches or the polishing
distortion slightly generated in the polishing portion 11 A by the
abrasive pad 13b. The polishing portion 11B corresponds to an
embodiment of the "third polishing portion" of the invention.
Specifically, in the thin film magnetic head, the insulating layer
made of alumina is made to be polished in the polishing portion 11B
until right before the magnetic layer made of permalloy or the like
(shield magnetic film or recording pole) is exposed to the surface
of the wafer. The third polishing portion may be composed of a
polishing portion for performing two or more degrees of polishing
depending on the application.
[0091] The abrasive pad 13c with a structure of a plurality of
(two, for example) layers is pasted on the surface of the platen
12c in the polishing portion 11 C. FIG. 3 shows an example of a
cross sectional configuration of the abrasive pad 13c including the
platen 12c.
[0092] The abrasive pad 13c has a two-layered structure of a
surface layer 13c.sub.1 and a bottom layer 13c.sub.2. The surface
layer 13c.sub.1 is formed of a porous polyurethane form, for
example, while the bottom layer 13c.sub.2 is formed of an elastic
material such as polyurethane or a gum rubber, which is softer than
the surface layer 13c.sub.1, or of a hard material such as ceramic
or plastic. The polishing portion 11C performs finishing through
lightly polishing the surface of the wafer by the abrasive pad 13c.
The polishing portion 11C corresponds to an embodiment of the
"second polishing portion" of the invention. Also, the same
abrasive liquid including slurry as in the polishing 11B is
supplied from the nozzle 15 to the abrasive pad 13c.
[0093] A cleaning pad 13d with a single-layered structure including
a brush with long pile is pasted on the surface of the platen 12d
in the cleaning portion 11D. The cleaning portion 11D completely
removes (cleans) the contamination left by the micro scratches or
slurry generated in the prior process by the cleaning pad 13d using
pure water or alcohol as the lubricant. The cleaning portion 11D
corresponds to the "cleaning portion" of the invention. The
cleaning portion may be formed of two or more cleaning portions for
performing different degrees of cleaning.
[0094] Next, operation of the polishing apparatus 1 will be
described.
[0095] In polishing portions 11A to 11C, and the cleaning portion
1ID of the polishing apparatus 1, the platens 12a to 12d and the
wafer holder 14 for holding the wafer W rotates in the reverse
direction of each other. The wafer W as a subject of polishing,
together with the wafer holder 14a, is moved to a position facing
the platens 12a tol2c of the polishing portions 11A to 11C and to
the platen 12d of the cleaning portion 11D in this order so as to
be polished and cleaned to a different degree.
[0096] First, in the polishing portion 11A, the protrusions of the
insulating film covering lots of different patterns in the wafer
(for example, the aggregated minute wiring patterns, a large
pattern or an isolated pattern) are removed (roughed) flat by the
platen 12a made of a hard grinder. In this case, the polishing
surface of the wafer W exhibits no pattern dependence since the
polishing surface is hard.
[0097] The wafer W to which roughing has been performed in the
polishing portion 11A is then moved to the polishing portion 11B.
In the polishing portion 11B, scratches and polishing distortion
slightly generated in the wafer by the platen 12a are removed
(medium polishing) by the hard abrasive pad 13b with a
single-layered structure. Specifically, in the thin film magnetic
head, the insulating layer made of alumina is polished until right
before the magnetic layer made of permalloy or the like (shield
magnetic film or recording pole) is exposed in the surface of the
wafer.
[0098] The wafer W to which the medium polishing has been performed
in the polishing portion 11B is then moved to the polishing portion
11C. In the polishing portion 11C, finishing is performed by the
abrasive pad 13c with a two-layered structure. In the abrasive pad
13c, the surface layer 13c.sub.1 made of a hard polyurethane form
or the like is supported by the bottom layer 13c.sub.2 made of a
softer material than the surface layer 13c.sub.1. Therefore, the
area between the surface of the wafer W and the polishing surface
can be made flat. In the process, few scratches or the like are
generated on the surface layer of the metallic layer such as coil
made of permalloy or copper in the manufacturing process of the
thin film magnetic head, for example. Even if there are scratches
generated, the scratches are not so serious as to give a damage
which is not restorable in the later process.
[0099] In the polishing portion 11C, the wafer W to which finishing
has been performed is then moved to the cleaning portion 11D. In
the cleaning portion 11D, the contamination left by the micro
scratches or slurry generated in the prior process are completely
cleaned together with pure water as the lubricant by the cleaning
pad 13d. Thereby, the final finishing is performed and a series of
the planarization process is completed.
[0100] As described, the polishing apparatus 1 according to the
embodiment comprises three polishing portions 11A to 11C. Roughing,
medium polishing and finishing of the wafer W are performed in the
polishing portions 11A to 11C respectively to planarize the wafer
W. In other words, the wafer W is roughly polished by the platen
12a made of rough and hard grinder in the polishing portion 11 A,
and then is medium-polished by the relatively hard abrasive pad 13b
in the polishing portion 11B. Thereby, protrusions of the wafer W
are removed without large scratches or cracks being generated while
the polishing surface of the wafer W exhibits no pattern
dependence. Further, finishing is performed by the fine soft
abrasive pad 13c in the polishing portion 11C. At last, micro
cracks and scratches are completely removed by the soft cleaning
pad 13d with long pile in the cleaning portion 11D.
[0101] In the embodiment, the planarization process can be thus
precisely performed so that performance of the semiconductor
integrated circuit and the composite thin film magnetic head can be
improved while yield of manufacturing is improved.
[0102] Further, in the embodiment, four wafer holders 14
sequentially move to the polishing portions 11A to 11C and the
cleaning portion 11D in order so that processing of the wafer W can
be continuously performed. At this time, appropriate polishing
processing depending on the subject of processing can be performed
on each wafer if the processing period is set separately for each
of the polishing portions 11A to 11C and the cleaning portion 11D.
When the processing period of the wafer does not meet mutually in
each portion, the wafer may be made stood by in the polishing
portions 11A to 11C and the cleaning portion 11D.
[0103] Second Embodiment]
[0104] FIG. 4 shows a configuration of a polishing apparatus 2
according to a second embodiment of the invention. Identical
reference numerals are given to the parts of the configuration
identical to the first embodiment and the description will be
omitted.
[0105] The polishing apparatus 2 comprises two polishing portions
21A and 21B, and a cleaning portion 21C. The polishing portions
21A, 21B and the cleaning portion 21C comprise platens 22a to 22c
respectively, and wafer holders (heads) 24 are placed facing each
of the platens 22a and 22c. The surfaces of the platens 22a to 22c
have different roughness from one another. The wafer W, together
with the wafer holder 24, is moved to the polishing portions 21A,
21B and to the cleaning portion 21C in this order to be polished
and cleaned to a different degree.
[0106] A hard polishing abrasive pad 23a with a single-layered
structure made of a hard resin such as a polyurethane form is
pasted on the surface of the platen 22a in the polishing portion
21A. The polishing liquid including slurry is supplied from a
nozzle (not shown in figure) to the abrasive pad 23a. Examples of
the slurry are alumina, silica and a mixture of both. In the
polishing portion 21A, the platen 22a may also be formed of a
grinder and perform polishing using the lubricant as in the first
embodiment. The polishing portion 21A first performs polishing to
remove protrusions of the insulating film covering lots of
different patterns in the wafer (the aggregated minute wiring
patterns, a large pattern or an isolated pattern, for example) by
the platen 22a. In the embodiment, the polishing portion 21A
corresponds to another embodiment of the "first polishing portion"
of the invention. The polishing surface of the platen 22a is the
hard abrasive pad 23a so that the polishing surface of the wafer W
exhibits no pattern dependence. Specifically, in the thin film
magnetic head, the insulating layer made of alumina is made to be
polished in the polishing portion 21A until right before the
magnetic layer made of permalloy or the like (shield magnetic film
or recording pole) is exposed in the surface of the wafer as in the
polishing portion 11B according to the first embodiment.
[0107] An abrasive pad 23b with a two-layered structure is pasted
on the surface of the platen 22b in the polishing portion 21B. The
abrasive pad 23b has the same configuration as that of the abrasive
pad 13c of the first embodiment, for example. The polishing portion
21B performs finishing through removing micro scratches and
polishing distortion slightly generated in the polishing portion
21A by lightly polishing the surface of the wafer by the abrasive
pad 23b. The polishing portion 21B corresponds to another
embodiment of the "second polishing portion" of the invention. The
polishing liquid including slurry is supplied from a nozzle to the
abrasive pad 23b. When the subject of polishing is a thin film
magnetic head, the film thickness of the shield pole, the recording
pole or the like after being polished in the polishing portion 21A
is precisely controlled in the polishing portion 21B and scratches
on the surface of the magnetic layer made of permalloy are removed
while recesses being 0.05 .mu.m or less.
[0108] A cleaning pad 23c having the same configuration as that of
the cleaning pad 11d of the first embodiment, for example, is
pasted on the surface of the platen 22c in the cleaning portion
21C. The cleaning portion 21C completely removes (cleans) the
contamination left by the micro scratches or slurry generated in
the prior process by the cleaning pad 23c using pure water or
alcohol as the lubricant. The cleaning portion 21C corresponds to
another embodiment of the "cleaning portion" of the invention.
[0109] First, in the polishing portion 21A of the polishing
apparatus 2 according to the embodiment, roughing is performed by
the abrasive pad 23a formed of, for example, a hard polyurethane
form. Thus, protrusions of the insulating film covering lots of
different patterns in the wafer are removed flat. The wafer W to
which roughing has been performed in the polishing portion 21A is
moved to the polishing portion 21B.
[0110] In the polishing portion 21B, finishing is performed through
removing micro scratches and polishing distortion slightly
generated in the wafer W in the polishing portion 21A by the
abrasive pad 23b with a two-layered structure. Specifically, in the
thin film magnetic head, the insulating layer made of alumina is
made to be polished in the polishing portion 21A until right before
the shield pole or the recording pole made of permalloy or the like
is exposed in the surface of the wafer.
[0111] Finally, when finishing is performed to the wafer W in the
polishing portion 21B, in the cleaning portion 21C, the
contamination left by the micro scratches or slurry generated in
the prior process is completely cleaned by the cleaning pad
23c.
[0112] As described, in the polishing apparatus 2 according to the
embodiment, roughing and finishing are performed in the two
polishing portions 21A and 21B by the abrasive pads 23a and 23b
having different roughness and hardness from each other. Further,
cleaning is performed in the cleaning portion 21C. As a result, in
the embodiment, the planarization of the wafer can be also
precisely performed so that performance of the devices such as the
semiconductor integrated circuit and the composite thin film
magnetic head can be improved while yield of manufacturing is
improved.
[0113] Next, a planarization process for a multi level interconnect
structure in the semiconductor integrated circuit and a
planarization process of the shield layer of the thin film magnetic
head and the pole tip of the top pole will be described as examples
of specific applications of the polishing apparatuses 1 and 2.
[0114] First, FIGS. 5A and 5B show an example in which the
apparatus is applied to a planarization process of a multi level
interconnect structure of a semiconductor integrated circuit. FIG.
5A shows a state in which an interlayer insulating film 32 about 2
.mu.m thick made of silicon oxide film (SiO.sub.2) is formed on a
plurality of metallic wiring patterns 31 with a thickness of 0.7
.mu.m, for example, on the field oxide film 30 which is formed on a
silicon substrate. The interlayer insulating film 32 has
protrusions 32a over the region where minute metallic wiring
patterns 31 are aggregated. FIG. 5B shows a state after the surface
is planarized by the above-mentioned polishing apparatuses 1 or
2.
[0115] As evident from the figure, in the embodiment, not only the
protrusions 32a over the aggregated metallic wiring patterns 31 but
areas between two regions where the metallic wiring patterns 31 are
aggregated are also precisely planarized. Accordingly, the wiring
layers thereon (not shown in figure) do not have breaks or failures
caused by electro-migration. As a result, in a multi level
interconnect structure of a semiconductor integrated circuit,
planarization processing without pattern dependence can be
performed while reliability of the device and yield of
manufacturing are remarkably improved.
[0116] Next, FIGS. 6A to 6C show an example in which the apparatus
is applied to a planarization process of the shield layer of the
thin film magnetic head and the pole tip of the top pole. As shown
in FIG. 6A, an insulating layer 41 about 3 to 5 .mu.m thick made of
alumina is formed on a substrate 40 made of altic by sputtering,
for example. Then a bottom shield layer 42 about 2 to 3 .mu.m thick
for a reproducing head made of magnetic materials such as permalloy
(NiFe) is formed on the insulating layer 41 by plating, for
example. An insulating layer 43 about 3 to 4 .mu.m thick made of
alumina is formed on the bottom shield layer 42. The insulating
layer 43 has protrusions 43a over the bottom shield layer 42.
[0117] FIG. 6B shows a state after the surface of the insulating
layer 43 is planarized by the above-mentioned polishing apparatuses
1 or 2. In such a thin film magnetic head, the surface is polished
to reach the bottom shield layer 42 so that the bottom shield layer
42 is exposed in the surface of the insulating layer 43. In the
related art, as described above, there are steps between the
insulating layer 43 and the bottom shield layer 42 so that either
the insulating layer 43 or the bottom shield layer 42 has a
recessed structure. In contrast, in the embodiment, polishing
processing divided into a plurality of steps with different
polishing hardness is performed so that planarization processing
without pattern dependence can be performed. In addition, there are
fewer recesses between the insulating layer 43 and the bottom
shield layer 42, and polishing speed and the thickness of the
remained film of both layers are controlled more precisely.
[0118] In the embodiment, then, as shown in FIG. 6C, a bottom
shield gap film 44, a magnetoresistive film 45, a lead layer (lead)
46 connected to the magnetoresistive film 45, a top shield gap film
47 and a top shield-cum-bottom pole 48 are formed in a thickness of
about 2 to 4 .mu.m. Then, an insulating layer 49 about 3 to 5 .mu.m
thick made of alumina is formed and the surface of the insulating
layer 49 is polished by the polishing apparatuses 1 or 2. In the
embodiment, recesses are rarely formed also at this time. Further,
after a write gap film 50 in a thickness of 0.2 to 0.3 .mu.m is
formed, a pole tip 51 a in a thickness of 2 to 3 .mu.m is formed.
An insulating layer in a thickness of 3 to 4 .mu.m is formed
thereon and then polished. In the embodiment, recesses are rarely
formed also at this time. At last, a thin film coil (not shown in
figure), a top magnetic layer (top pole) 51b, an over coat layer
(not shown in figure) and the like are formed and the manufacturing
process of the thin film magnetic head is completed.
[0119] As described, it is necessary to control the amount of
polishing by the polishing apparatus and to keep excellent
uniformity in thickness of bottom shield layer, the top shield
layer and the pole tip in the wafer after being polished in order
to improve performance of the thin film magnetic head. In the
polishing apparatus of the related art, however, when polishing the
bottom shield layer, the top shield layer or the pole tip, recesses
are formed between the insulating layer and the top or bottom
shield layers or the pole tip, which results in deterioration of
the performance of the thin film magnetic head. In contrast, in the
embodiment, a plurality of polishing processing with different
polishing degrees are performed so that the polishing speed of the
insulating layer and the magnetic layer exposed in the surface of
the insulating layer is controlled more precisely. The uniformity
in thickness of the layers in the wafer is also improved and there
is no scratches or the like on the surface of the magnetic layer.
Further recesses become small and reproducing performance is
improved. Accordingly, it becomes easier to form a narrow track,
which is an important process for manufacturing a thin film
magnetic head. Especially, performance of the recording head is
remarkably improved.
EXAMPLE
[0120] In FIG. 7, "a" shows data of polishing an alumina insulating
film about 6 .mu.m thick formed on a permalloy pattern about 3.0
.mu.m thick of a shield layer by about 2 .mu.m with 3000.sup.th
vitrified grinder by the method of the related art in the thin film
magnetic head, and "b" shows data of measuring the size of the
steps after polishing the surface by 3 .mu.m using an abrasive pad
with a two-layered structure made of IC 1000 and Suba 400 of the
related art. In FIG. 7, the horizontal axis represents the
measuring position in the wafer (mm) and the vertical axis
represents the thickness of the remained film (nm). In the result
"a", the shield layer made of permalloy was not exposed and
existence of scratches on the surface was unknown. In other
experiments, however, lots of scratches were found on the surface
of the shield layer when the shield layer made of permalloy was
exposed. The result "b" is the one measuring the size of the steps
of the surface of the wafer when the shield layer made of permalloy
was exposed. Micro scratches were found here and there on the
surface of the shield layer, depending on selection of slurry.
These scratches were, however, not serious. Recesses were as
relatively large as 150 to 300 nm depending on selection of
slurry.
[0121] In contrast, FIGS. 8A and 8B show the result of performing
planarization by the polishing apparatus 1 according to the
embodiment. In the FIGS. 8A and 8B, numerals from 1 to 9 on the
horizontal axis represent the horizontal position and correspond to
the measuring position in the wafer W shown in FIG. 9. The 3000th
resin was used as the grinder. As a sample, an insulating film 4.5
.mu.m thick made of alumina was formed on a magnetic layer 3 .mu.m
thick made of permalloy and the insulating film was planarized by
the polishing apparatus 1. FIG. 8A shows data of the thickness of
the remained film of the insulating layer made of alumina after
being polished by 1.5 .mu.m. In the figure, "a" represents the
original film thickness of the insulating layer, "b" represents the
film thickness of the insulating layer after being polished and "c"
represents the amount of polishing performed on the insulating
layer.
[0122] On the other hand, FIG. 8B shows data of measuring the
thickness of the remained film of the magnetic layer made of
permalloy after being polished by 1.5 .mu.m. In the figure, "a"
represents the original film thickness of the insulating layer, "b"
represents the film thickness of the insulating layer after being
polished and "c" represents the amount of recesses. It is evident
from these that the film thickness becomes constant all over the
wafer, which means planarization is precisely performed, when the
polishing apparatus 1 according to the embodiment is used. Further,
recesses between the insulating film made of alumina and the shield
layer made of permalloy are all suppressed to 50 .mu.m or less.
[0123] The invention has been described by referring to the
embodiments and the example. However, the invention is not limited
to the embodiments and the example but various modifications are
possible. The number of the polishing portions is three in the
first embodiment and two in the second embodiment. However, any
number equal to or more than two of the polishing portions may be
provided. Specifically, the third polishing portion which performs
medium polishing may comprise a plurality of polishing portions for
performing different degrees of polishing. Further, combination of
the grinder and the abrasive pad or the like is not limited to the
above-mentioned embodiments but various combinations are also
possible. The point is to continuously perform rough polishing and
fine polishing in order in a plurality of polishing portions in one
apparatus.
[0124] Further, although moving the wafer W between each two of the
polishing portions and the cleaning portion is made to be performed
by rotating the wafer holder 14 in the above-mentioned embodiments,
it may be performed by rotating the pedestal 1 instead.
[0125] Although disk-shaped grinders are used as the grinders for
performing roughing in the above-mentioned embodiments, a
ring-shaped (or cup-shaped) grinder 60 may be used for polishing
the surface of the wafer W as shown in FIG. 10. At this time, the
grinder 60 itself rotates with rotating means (not shown in figure)
and is moved relative to the surface of the wafer W by moving means
(not shown in figure) in the direction shown by an arrow in the
figure, and polishes the whole surface of the wafer W.
[0126] Further, although one subject of polishing is polished in
the first to third polishing portions in order in the embodiments,
it is possible to perform the same type of polishing on two or more
subjects simultaneously in each of the first to third polishing
portions so that a plurality of subjects of polishing can be
simultaneously processed in order to improve the productivity.
[0127] Moreover, although the polishing portions and the cleaning
portion are formed on one body in the embodiments, they may be
formed as separate apparatuses. FIG. 11 shows one example in which
a polishing apparatus 70 comprising three polishing portions 71A to
71C, and a cleaning apparatus 80 comprising two cleaning portions
81A, 81B with different degrees of cleaning and a drying portion
81C are connected by an underwater elevator 90. The polishing
portions 71A to 71C in the polishing apparatus 70 are composed of a
platen 72 and a waferholder 73 and correspond to the polishing
portions 11A to 11C of the first embodiment. In the polishing
apparatus 70, the wafer W sent in through a loader 74 is moved to
each of the polishing portions 71A to 71C by an arm robot 75 to
receive roughing, medium polishing and finishing. The wafer to
which finishing has been performed is moved in a wet state to the
cleaning apparatus 80 by the underwater elevator 90. In the
cleaning portion 80, the wafer W is roughly cleaned in the cleaning
portion 81A, finely cleaned by the cleaning portion 81B and
spin-dried in the drying portion 81C in order. At last, the wafer W
is taken out from the cleaning apparatus 80 through an unloader
82.
[0128] In the invention, the subject of polishing is not limited to
the ones mentioned in the embodiments but may be other parts of
wafers in a semiconductor integrated circuit or a thin film
magnetic head, or other devices. Specifically, in a case of a thin
film magnetic head, the polishing apparatus and the polishing
method of the invention is applicable to the polishing of ABS in a
final process mentioned above to adjust throat height.
[0129] As described, according to the polishing apparatus and the
polishing method of the invention, a plurality of polishing
processing from roughing to fine finishing can be performed in
order since polishing processing with different degrees is
performed on one subject of polishing. As a result, the
planarization process can be precisely performed and precision of
microfabrication of the semiconductor integrated circuit and the
thin film magnetic head can be improved while yield of
manufacturing is improved.
[0130] Further, according to the method of manufacturing a
semiconductor device of the invention, precision of
microfabrication and yield of manufacturing are improved since the
planarization process is performed using the polishing apparatus of
the invention.
[0131] Moreover, according to the method of manufacturing a thin
film magnetic head, precision of microfabrication and yield of
manufacturing are improved since the planarization process is
performed using the polishing apparatus of the invention.
* * * * *