U.S. patent application number 11/596714 was filed with the patent office on 2008-11-06 for substrate peripheral portion measuring device, and substrate peripheral portion polishing apparatus.
This patent application is currently assigned to EBARA CORPORATION. Invention is credited to Hirofumi Ichihara, Kenya Ito, Yasunari Suto, Mitsuo Tada, Tamami Takahashi.
Application Number | 20080274670 11/596714 |
Document ID | / |
Family ID | 35450717 |
Filed Date | 2008-11-06 |
United States Patent
Application |
20080274670 |
Kind Code |
A1 |
Tada; Mitsuo ; et
al. |
November 6, 2008 |
Substrate Peripheral Portion Measuring Device, and Substrate
Peripheral Portion Polishing Apparatus
Abstract
A projecting/receiving unit (52) projects a laser light to a
peripheral portion (30) and receives the reflected light while a
liquid is being fed to a substrate (14) and is flowing on the
peripheral portion (30). A signal processing controller (54)
processes the electric signal of the reflected light to decide the
state of the peripheral portion (30). The state of the peripheral
portion being polished is monitored. Moreover, the polish end point
is detected. A transmission wave other than the laser light may
also be used. The peripheral portion (30) may also be enclosed by a
passage forming member thereby to form a passage properly. The
peripheral portion can be properly measured even in the situation
where the liquid is flowing on the substrate peripheral
portion.
Inventors: |
Tada; Mitsuo; (Tokyo,
JP) ; Suto; Yasunari; (Tokyo, JP) ; Ichihara;
Hirofumi; (Tokyo, JP) ; Ito; Kenya; (Tokyo,
JP) ; Takahashi; Tamami; (Tokyo, JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W., SUITE 800
WASHINGTON
DC
20006-1021
US
|
Assignee: |
EBARA CORPORATION
TOKYO
JP
|
Family ID: |
35450717 |
Appl. No.: |
11/596714 |
Filed: |
May 23, 2005 |
PCT Filed: |
May 23, 2005 |
PCT NO: |
PCT/JP05/09821 |
371 Date: |
November 16, 2006 |
Current U.S.
Class: |
451/6 ;
257/E21.23 |
Current CPC
Class: |
G01N 29/44 20130101;
H01L 21/67242 20130101; H01L 21/67023 20130101; B24B 9/065
20130101; B24B 49/12 20130101; H01L 21/67075 20130101; G01N 21/9501
20130101 |
Class at
Publication: |
451/6 |
International
Class: |
B24B 49/12 20060101
B24B049/12 |
Claims
1. A substrate peripheral portion measuring device for measuring
the state of the peripheral portion of a substrate, comprising: a
wave transceiver for transmitting a transmission wave to said
peripheral portion while a liquid is being fed to said substrate
and is flowing on said peripheral portion, and for receiving a
reflected wave from said peripheral portion; and a received wave
processing unit for processing the signal of said reflected wave to
decide the state of said peripheral portion.
2. A substrate peripheral portion measuring device in accordance
with claim 1, further comprising: a passage forming portion
enclosing said peripheral portion for forming a passage to feed
said liquid onto said peripheral portion; wherein the wave
transmitting/receiving portion of said wave transceiver is arranged
in said passage.
3. A substrate peripheral portion measuring device in accordance
with claim 2, wherein the wall face of said passage has a wave
collecting face shaped to further reflect said reflected wave
thereby to collect said reflected wave; and wherein said wave
transceiver has a portion for receiving said reflected wave at a
position where said reflected wave is collected.
4. A substrate peripheral portion measuring device in accordance
with claim 1, further comprising: a liquid removing unit for
blowing away said liquid from said peripheral portion; wherein said
wave transceiver transmits said transmission wave to the place
where said liquid is blown away by said liquid removing unit.
5. A substrate peripheral portion measuring device in accordance
with claim 1, further comprising: a liquid blocking unit enveloping
said peripheral portion partially for blocking the arrival of the
liquid at said peripheral portion; wherein said wave transceiver is
disposed to transmit/receive the wave through said liquid blocking
unit.
6. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit decides
the state of said peripheral portion on the basis of the relative
change of said reflected wave accompanying the change of said
substrate.
7. A substrate peripheral portion measuring device in accordance
with claim 1, wherein that said received wave processing unit
decides the state of said peripheral portion on the basis of the
time differentiation of said reflected wave accompanying the change
of said substrate.
8. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit decides
the state of said peripheral portion by performing a frequency
analysis of said reflected wave.
9. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit performs
an end point detection of the processing of said peripheral
portion.
10. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit monitors
the state of the treating procedure of said peripheral portion.
11. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit detects a
defect of said peripheral portion.
12. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said wave transceiver transmits at least one
of a laser light, a while light, a microwave, an ultrasonic wave
and an alternating magnetic field signal as a transmission wave to
said peripheral portion.
13. A substrate peripheral portion measuring device in accordance
with claim 1, wherein a plurality of said wave transceivers are
arranged along the peripheral portion of said substrate.
14. A substrate peripheral portion measuring device in accordance
with claim 1, wherein the substrate peripheral portion to be
measured has a silicon nitride film, a silicon oxide film, a
poly-silicon film, a barrier film of Ta, TaN, TiN, Ti or the like,
or a metal film of Cu, W or the like.
15. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit clears the
signal of said reflected wave of noise components.
16. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said wave transceiver is configured to
project a laser light and to receive a reflected light; and wherein
a beam size is set according to the movement of the turning
wafer.
17. A substrate peripheral portion measuring device in accordance
with claim 1, further comprising: a modulation unit for modulating
the laser light projected as said transmission wave by said wave
transceiver; and a synchronism detecting unit for detecting the
reflected light received as said reflected wave by said wave
transceiver, in synchronism with the modulation by said modulation
unit.
18. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said wave transceiver is configured to send
transmission waves of a plurality of kinds; and wherein said
reflected wave processing unit is configured to process reflected
waves of a plurality of kinds received by said wave
transceiver.
19. A substrate peripheral portion measuring device in accordance
with claim 18, wherein the kind of transmission wave to be used for
the measurement is changed according to the material of said
peripheral portion of said substrate.
20. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit decides
the state of said peripheral portion on the basis of zone data
obtained from reflected waves of measurement zones disposed along
the outer circumference of said substrate.
21. A substrate peripheral portion measuring device in accordance
with claim 20, wherein said received wave processing unit decides
the state of said peripheral portion by comparing the zone data
obtained from said measurement zones.
22. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit decides
the state of said peripheral portion on the basis of the change of
the reflection according to the material change of the surface of
said peripheral portion accompanying the treatment of said
substrate.
23. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said received wave processing unit decides
the state of said peripheral portion on the basis of the pattern
change of said reflected wave according to the material change of
the surface of said peripheral portion accompanying the treatment
of said substrate.
24. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said substrate peripheral portion measuring
device belongs to a substrate peripheral portion polishing
apparatus for polishing the peripheral portion of a substrate and
measures the polished state of the peripheral portion of the
substrate being polished.
25. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said substrate peripheral portion measuring
device belongs to a substrate treating apparatus provided with a
substrate peripheral portion polishing apparatus for polishing the
peripheral portion of a substrate and measures the polished state
of the peripheral portion of the substrate being polished.
26. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said substrate peripheral portion measuring
device belongs to a substrate rinsing apparatus and measures the
polished state of the peripheral portion of the substrate being
rinsed.
27. A substrate peripheral portion measuring device in accordance
with claim 1, wherein said substrate peripheral portion measuring
device belongs to substrate treating apparatus provided with a
substrate rinsing apparatus and measures the polished state of the
peripheral portion of the substrate being rinsed.
28. A substrate peripheral portion polishing apparatus comprising:
a substrate holder for holding a substrate; a substrate turning
unit for turning said substrate; a liquid supply unit for supplying
said substrate with a liquid; an peripheral portion polishing unit
for polishing the peripheral portion of said substrate while being
supplied with said liquid; a wave transceiver for transmitting a
transmission wave to said peripheral portion while said liquid is
flowing on said peripheral portion, and for receiving a reflected
wave from said peripheral portion; a received wave processing unit
for processing the signal of said reflected wave to decide the
polished state of said peripheral portion; and a control unit for
controlling the polish of said peripheral portion in accordance
with the polished state of said peripheral portion obtained by said
received wave processing unit.
29. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: a passage forming
portion enclosing said peripheral portion for forming a passage to
feed said liquid onto said peripheral portion; wherein the wave
transmitting/receiving portion of said wave transceiver is arranged
in said passage.
30. A substrate peripheral portion polishing apparatus in
accordance with claim 29, wherein the wall face of said passage has
a wave collecting face shaped to further reflect said reflected
wave thereby to collect said reflected wave; and wherein said wave
transceiver has a portion at a position, where said reflected wave
is collected, for receiving said reflected wave.
31. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: a liquid removing
unit for blowing away said liquid from said peripheral portion;
wherein said wave transceiver transmits said transmission wave to
the place where said liquid is blown away by said liquid removing
unit.
32. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: a liquid blocking
unit enveloping said peripheral portion partially for blocking the
arrival of the liquid at said peripheral portion; wherein said wave
transceiver is disposed to transmit/receive the wave through said
liquid blocking unit.
33. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said received wave processing
unit detects the polish end point of the peripheral portion; and
wherein said control unit ends the polish of said peripheral
portion when the polish end point of said peripheral portion is
detected.
34. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said received wave processing
unit monitors the state of the polishing procedure of the
peripheral portion; and wherein said control unit controls the
polishing condition of said peripheral portion in accordance with
the state of the polishing procedure of said peripheral
portion.
35. A substrate peripheral portion polishing apparatus in
accordance with claim 34, wherein said control unit controls at
least one of the turning speed of said substrate, the pushing force
of the polishing tool to said peripheral portion, the feed movement
of the polishing tape, the feed speed of the polishing tape, the
relative movement of the polishing head with respect to the
substrate, the relative moving speed of the polishing head with
respect to the substrate, and the feed rate of said liquid.
36. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said received wave processing
unit decides whether or not the peripheral portion is
defective.
37. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: an abnormality
detecting unit for detecting that a polish abnormality has occurred
when the polish end point is not detected even if the polishing
time reaches a predetermined maximum polishing time; wherein said
control unit stops the polish when the abnormality is detected by
said abnormality detecting unit.
38. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: an abnormality
detecting unit for detecting that a polish abnormality has occurred
when the waveform of the reflected wave is abnormal; wherein said
control unit stops the polish when the abnormality is detected by
said abnormality detecting unit.
39. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: a tool exchange
informing unit for informing the arrival of an exchanging timing of
a polishing tool when the polishing rate obtained from said
reflected wave lowers to a predetermined tool exchanging threshold
rate.
40. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said wave transceiver is
configured to send a plurality of kinds of transmission waves; and
wherein the kind of said transmission wave to be used for the
measurement is changed according to the proceeding situation of the
polishing procedure determined from said reflected wave.
41. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said wave transceiver is
configured to send a plurality of kinds of transmission waves; and
wherein the kind of said transmission wave to be used for the
measurement is changed in association with the change of the
polishing condition by said control unit.
42. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said control unit controls the
polish of said substrate on the basis of said polishing state and
the control parameter of an peripheral portion polishing tool.
43. A substrate peripheral portion polishing apparatus in
accordance with claim 42, wherein said control unit interchanges
the control based on said control parameter and the control based
on said polishing state, in accordance with the progress of the
polishing procedure of the substrate.
44. A substrate peripheral portion polishing apparatus in
accordance with claim 28, wherein said received wave processing
unit detects the polish end point by comparing the polish end point
target set according to the reflected wave at an initial polishing
stage and the reflected wave obtained from said wave
transceiver.
45. A substrate peripheral portion polishing apparatus in
accordance with claim 28, further comprising: an end time setting
unit for setting the polish end time, at which the polish end point
is reached, on the basis of a reference time till a predetermined
reference polishing state is obtained in the polishing
procedure.
46. A substrate rinsing apparatus comprising: a substrate holder
for holding a substrate; a substrate turning unit for turning said
substrate; a liquid supply unit for supplying said substrate with a
liquid; a wave transceiver for transmitting a transmission wave to
the peripheral portion of said substrate while said liquid is
flowing on said peripheral portion, and for receiving a reflected
wave from said peripheral portion; and a received wave processing
unit for processing the signal of said reflected wave to decide the
polished state of said peripheral portion.
47. A substrate peripheral portion measuring method for measuring
the state of the peripheral portion of a substrate, including:
transmitting a transmission wave to said peripheral portion while a
liquid is being fed to said substrate and is flowing on said
peripheral portion; receiving a reflected wave from said peripheral
portion; and processing the signal of said reflected wave to decide
the state of said peripheral portion.
48. A substrate peripheral portion polishing method including:
holding a substrate; turning said substrate; supplying said
substrate with a liquid; polishing the peripheral portion of said
substrate while said liquid is being supplied; transmitting a
transmission wave to said peripheral portion while said liquid is
flowing on said peripheral portion; receiving a reflected wave from
said peripheral portion; processing the signal of said reflected
wave to decide the polished state of said peripheral portion; and
controlling the polish of said peripheral portion in accordance
with the polished state of said peripheral portion.
49. A substrate rinsing method including: holding a substrate;
turning said substrate; supplying said substrate with a liquid;
transmitting a transmission wave to said peripheral portion while
said liquid is flowing on the peripheral portion of said substrate;
receiving a reflected wave from said peripheral portion; and
processing the signal of said reflected wave to decide the polished
state of said peripheral portion.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a substrate peripheral
portion measuring device for measuring the state of the peripheral
portion of a substrate. The substrate peripheral portion measuring
device belongs to a semiconductor wafer peripheral portion
polishing apparatus, for example, and is used to measure the
polishing state of the peripheral portion being polished.
[0003] 2. Background
[0004] As miniaturization and high integration of a semiconductor
device advance, management of particles becomes more important. One
of major problems in the management of the particles is the dust
formation, which is caused by the surface roughness to occur on the
circumferential peripheral portion of a semiconductor wafer (or
substrate) while the semiconductor device is being
manufactured.
[0005] In the semiconductor device manufacturing process, flaws or
a number of minute needle-shaped projections may be formed at the
circumferential peripheral portion of the semiconductor wafer
thereby to cause the surface roughness. The needle-shaped
projections are broken to produce the particles while the
semiconductor wafer is being transferred or processed. These
particles lead to a drop in the production yield. Thus, it is
necessary to remove the needle-shaped projections from the
circumferential peripheral portion of the semiconductor wafer.
[0006] In recent years, moreover, there is a tendency that Cu is
used as the wiring material for the semiconductor device and that
the Low-k material is used as an insulating material. When the Cu
formed on the circumferential peripheral portion of the
semiconductor wafer sticks to the arm of a transfer robot or a
cassette for housing the substrate, the Cu can cause the so-called
"cross contamination", in which it diffuses to contaminate the
remaining steps. On the other hand, the very fragile Low-k film
leaves the circumferential peripheral portion of the substrate
during the CMP working treatment thereby to damage or scratch the
pattern face. It is, therefore, important to clear the
circumferential peripheral portion of the semiconductor wafer of
the Cu or Low-k film.
[0007] As the pattern of the semiconductor wafer becomes highly
dense, the sub-micron contamination is deemed as a problem and
highlighted as a serious cause for a defect in the wafer process,
although not deemed serious in the prior art. Under this
background, it is also important to polish off the film or the like
of the wafer peripheral portion.
[0008] In the general peripheral portion polishing technique of the
prior art, the turning wafer is fed with a liquid such as water. A
polishing tool such as a polishing tape is pushed to the peripheral
portion thereby to polish the peripheral portion.
[0009] The prior art cannot grasp the state of the peripheral
portion being polished. Therefore, a total polishing time is
determined to manage the polishing process. In order to determine
the total polishing time, the sample wafer is subjected at first to
a polishing treatment of an initial stage, and the wafer end face
is then observed by a camera thereby to examine the flaws left in
the defective portion. Then, an additional polishing time necessary
for a target finish state is calculated, and the additional polish
is performed. The additional polishing time is calculated by using
a polishing rate. The additional polish and the subsequent camera
observation are repeated to determine the total polishing time. The
total polishing time thus obtained is applied to the subsequent
wafer polish.
[0010] Moreover, a wafer peripheral portion measuring device has
also been proposed in the prior art. For example, the measurement
device of JP-A-2003-139523 (pages 3 and 4, FIG. 1) illuminates the
peripheral portion with a diffusive light to photograph the
peripheral portion thereby to detect the defect of the peripheral
portion from the photograph.
[0011] In case, however, the total polishing time is determined by
means of a sample wafer, it takes a remarkably long time to repeat
the additional polish and the camera observation. Moreover, the
total polishing time required for the practice is different for
each wafer. Even if the total polishing time is determined with the
sample wafer, the polish may be short or excessive for another
wafer so that the process is not stabilized to lower the
productivity.
[0012] On the other hand, the wafer peripheral portion measuring
device of the prior art has failed to consider the measurement in
the presence of a liquid such as water. Therefore, the device of
the prior art is not suited for the measurement in the peripheral
portion polishing apparatus (i.e., in-line) and during the polish
(i.e., in situ). If the peripheral portion could be measured during
the polish in the polishing apparatus, the peripheral portion
polishing process could be properly managed to improve the
productivity.
[0013] Here, the background art of the invention has been described
on the polish of the wafer peripheral portion. A similar background
can apply to purposes other than the peripheral portion polish. For
example, there is desired a technique for measuring the peripheral
portion in the rinsing process.
DISCLOSURE OF THE INVENTION
[0014] The present invention has been conceived under the
background thus far described and has an object to provide a
peripheral portion measuring device for measuring the state of the
peripheral portion properly. This state of the peripheral portion
typically means the surface roughness due to flaws or minute
projections, and means that the material used in the device
manufacturing process, such as Cu or a Low-k material as the
insulating material sticks to the surface of the circumferential
peripheral portion of the substrate or forms a film-shaped
substance.
[0015] According to the invention, there is provided a substrate
peripheral portion measuring device for measuring the state of the
peripheral portion of a substrate. The substrate peripheral portion
measuring device comprises: a wave transceiver for transmitting a
transmission wave to the peripheral portion while a liquid is being
fed to the substrate and is flowing on the peripheral portion, and
for receiving a reflected wave from the peripheral portion; and a
received wave processing unit for processing the signal of the
reflected wave to decide the state of the peripheral portion. Thus,
according to the invention, the peripheral portion can be properly
measured even in the situation where the liquid flows on the
peripheral portion.
[0016] Here, the liquid is exemplified by water, and the
transmission wave is exemplified by a laser light. The kinds of the
liquid and the transmission wave may not be limited but be within a
measurable range.
[0017] In the invention, the peripheral portion of the substrate
includes a bevel portion and an edge portion. The bevel portion is
the outer circumference of the substrate, and the edge portion is
the two side portions of the bevel portion (i.e., the end portions
of the surface and the back). The device of the invention may
measure the bevel portion, the edge portion or both the bevel
portion and the edge portion. Therefore, the later-described
peripheral portion treatment includes the treatments of the bevel
portion and the edge portion.
[0018] The substrate peripheral portion measuring device of the
invention preferably comprises a passage forming portion enclosing
the peripheral portion for forming a passage to feed the liquid
onto the peripheral portion, and the wave transmitting/receiving
portion of the wave transceiver is arranged in the passage. By thus
providing the passage forming portion, the liquid flow at the
peripheral portion can be stabilized to improve the measuring
ability.
[0019] The wall face of the passage preferably has a wave
collecting face shaped to further reflect the reflected wave
thereby to collect the reflected wave, and the wave transceiver has
a portion at a position, where the reflected wave is collected, for
receiving the reflected wave. This configuration causes the wall
face of the passage not only to guide the liquid but also to
function as the wave collecting face for collecting the reflected
waves. As a result, the wave transceiver can receive the reflected
light properly thereby to improve the measuring ability.
[0020] The device of the invention preferably comprises a liquid
removing unit for blowing away the liquid from the peripheral
portion, and the wave transceiver transmits the transmission wave
to the place where the liquid is blown away by the liquid removing
unit. By thus providing the liquid removing unit, the influences of
the liquid can be reduced to improve the measurement precision.
[0021] The device of the invention preferably comprises a liquid
blocking unit enveloping the peripheral portion partially for
blocking the arrival of the liquid at the peripheral portion, and
the wave transceiver is disposed to transmit/receive the wave
through the liquid blocking unit. By thus providing the liquid
blocking unit, the influence of the liquid can be reduced to
improve the measurement precision.
[0022] In the invention, the reflected wave processing unit may
decide the state of the peripheral portion on the basis of the
relative change of the reflected wave accompanying the change of
the substrate. The reflected wave processing unit may decide the
state of the peripheral portion on the basis of the time
differentiation of the reflected wave accompanying the change of
the substrate. The reflected wave processing unit may decide the
state of the peripheral portion by performing a frequency analysis
of the reflected wave.
[0023] In the invention, moreover, the reflected wave processing
unit may perform an end point detection of the processing of the
peripheral portion. The reflected wave processing unit may monitor
the state of the treating procedure of the peripheral portion. The
reflected wave processing unit may detect a defect of the
peripheral portion. Here in the invention, the peripheral portion
treatment includes a polishing treatment and an etching treatment.
More specifically, the peripheral portion treatment includes a
bevel polishing, an edge polishing, a bevel etching and an edge
etching. One treatment may be carried out, and a plurality of
treatments may also be carried out.
[0024] In the invention, moreover, the wave transceiver may
transmit at least one of a laser light, a while light, a microwave,
an ultrasonic wave and an alternating magnetic field signal as a
transmission wave to the peripheral portion. The typical
transmission wave is the laser light.
[0025] Moreover, a plurality of the wave transceivers may be
arranged along the peripheral portion of the substrate. Moreover,
the substrate peripheral portion to be measured may have a silicon
nitride film, a silicon oxide film, a poly-silicon film, a barrier
film of Ta, TaN, TiN, Ti or the like, or a metal film of Cu, W or
the like.
[0026] Preferably, the reflected wave processing unit has means for
clearing the signal of the reflected wave of noise components. By
thus removing the noise components, the signal indicating the state
of the peripheral portion can be obtained precisely and stably.
[0027] Preferably, the wave transceiver is configured to project a
laser light and to receive a reflected light; and a beam size is
set according to the movement of the turning wafer. By thus setting
the beam size according to the wafer movement, the state of the
peripheral portion of the wafer can be precisely measured even if
the turning wafer moves to some extent.
[0028] Preferably, the device of the invention comprises: a
modulation unit for modulating the laser light projected as the
transmission wave by the wave transceiver; and a synchronism
detecting unit for detecting the reflected light received as the
reflected wave by the wave transceiver, in synchronism with the
modulation by the modulation unit. By thus performing the
modulation of the laser light and the synchronous detection of the
reflected light, the measurement sensitivity can be augmented to
improve the measuring ability.
[0029] Preferably, the wave transceiver is configured to send a
plurality of kinds of transmission waves, and the signal processing
unit is configured to process a plurality of kinds of reflected
waves received by the wave transceiver. Here, a plurality of kinds
of the transmission waves are those of at least two kinds of the
aforementioned laser light, white light, microwave, ultrasonic wave
and alternating magnetic field signal. The kind of transmission
wave to be used for the measurement is changed according to the
material of the substrate peripheral portion to be measured.
Moreover, the kind of transmission wave may be changed as the
substrate treatment such as the polish advances. By thus
selectively using the plurality of kinds of transmission waves, the
proper transmission waves can be used to improve the measuring
ability.
[0030] Preferably, the reflected wave processing unit decides the
state of the peripheral portion on the basis of zone data obtained
from reflected waves of measurement zones disposed along the outer
circumference of the substrate. Here, the zone data represent the
reflected waves of the measurement zones and are an average of the
amplitudes of the reflected waves obtained from a plurality of
measurement zones. By using the zone data, the state of the
substrate peripheral portion can be properly grasped to improve the
measuring ability.
[0031] Preferably, the reflected wave processing unit decides the
state of the peripheral portion by comparing the zone data obtained
from the measurement zones. By thus comparing the zone data of the
measurement zones, the situation of the peripheral portion can be
grasped with reference to the measurement zones. As a result, the
state of the substrate peripheral portion can be properly grasped
to improve the measuring ability.
[0032] Preferably, the reflected wave processing unit decides the
state of the peripheral portion on the basis of the reflection
according to the material change of the surface of the peripheral
portion accompanying the treatment of the substrate. By thus noting
the change of the reflection according to the material change of
the surface of the peripheral portion, the state of the peripheral
portion can be precisely decided to improve the measuring
ability.
[0033] Preferably, the reflected wave processing unit decides the
state of the peripheral portion on the basis of the change of the
pattern change of the reflected wave according to the material
change of the surface of the peripheral portion accompanying the
treatment of the substrate. By thus noting the change of the
reflection pattern according to the material change of the surface
of the peripheral portion, the state of the peripheral portion can
be precisely decided to improve the measuring ability.
[0034] Moreover, the measuring device of the invention may belong
to a substrate peripheral portion polishing apparatus for polishing
the peripheral portion of a substrate, and may measure the polished
state of the peripheral portion of the substrate being polished.
Moreover, the measuring device may belong to a substrate treating
apparatus provided with a substrate peripheral portion polishing
apparatus for polishing the peripheral portion of a substrate, and
may measure the polished state of the peripheral portion of the
substrate being polished.
[0035] Moreover, the measuring device may belong to a substrate
rinsing apparatus, and may measure the polished state of the
peripheral portion of the substrate being rinsed. Moreover, the
measuring device may belong to substrate treating apparatus
provided with a substrate rinsing apparatus, and may measure the
polished state of the peripheral portion of the substrate being
rinsed.
[0036] According to another aspect of the invention, there is
provided a substrate peripheral portion polishing apparatus which
comprises: a substrate holder for holding a substrate; a substrate
turning unit for turning the substrate; a liquid supply unit for
supplying the substrate with a liquid; an peripheral portion
polishing unit for polishing the peripheral portion of the
substrate while being supplied with the liquid; a wave transceiver
for transmitting a transmission wave to the peripheral portion
while the liquid is flowing on the peripheral portion, and for
receiving a reflected wave from the peripheral portion; a received
wave processing unit for processing the signal of the reflected
wave to decide the polished state of the peripheral portion; and a
control unit for controlling the polish of the peripheral portion
in accordance with the polished state of the peripheral portion
obtained by the received wave processing unit. Thus, the invention
can measure the peripheral portion properly even in the situation
where the liquid flows on the peripheral portion. Therefore, the
invention can measure the state of the peripheral portion being
polished.
[0037] Preferably, the substrate peripheral portion polishing
apparatus comprises a passage forming portion enclosing the
peripheral portion for forming a passage to feed the liquid onto
the peripheral portion, and the wave transmitting/receiving portion
of the wave transceiver is arranged in the passage. By thus
providing the passage forming portion, the flow of the liquid on
the peripheral portion can be stabilized to improve the measuring
ability.
[0038] Preferably, the wall face of the passage has a wave
collecting face shaped to further reflect the reflected wave
thereby to collect the reflected wave and the wave transceiver has
a portion at a position, where the reflected wave is collected, for
receiving the reflected wave. This configuration causes the wall
face of the passage not only to guide the liquid but also to
function as the wave collecting face for collecting the reflected
waves. As a result, the quantity of the reflected waves received by
the wave transceiver can be augmented to improve the measuring
ability.
[0039] Preferably, the apparatus comprises a liquid removing unit
for blowing away the liquid from the peripheral portion, and the
wave transceiver transmits the transmission wave to the place where
the liquid is blown away by the liquid removing unit. By thus
providing the liquid removing unit, the influence of the liquid can
be reduced to improve the measurement precision.
[0040] Preferably, the apparatus comprises a liquid blocking unit
enveloping the peripheral portion partially for blocking the
arrival of the liquid at the peripheral portion, and the wave
transceiver is disposed to transmit/receive the wave through the
liquid blocking unit. By thus providing the liquid blocking unit,
the influence of the liquid can be reduced to improve the
measurement precision.
[0041] In the apparatus, the received wave processing unit may
detect the polish end point of the peripheral portion, and the
control unit may end the polish of the peripheral portion when the
polish end point of the peripheral portion is detected. Moreover,
the received wave processing unit may monitor the state of the
polishing procedure of the peripheral portion, and the control unit
may control the polishing condition of the peripheral portion in
accordance with the state of the polishing procedure of the
peripheral portion. The control unit may control at least one of
the turning speed of the substrate, the pushing force of the
polishing tool to the peripheral portion, the feed movement of the
polishing tape, the feed speed of the polishing tape, the relative
movement of the polishing head with respect to the substrate, the
relative moving speed of the polishing head with respect to the
substrate, and the feed rate of the liquid. The polishing condition
can be effectively changed by controlling at least one of the
turning speed of the substrate, the pushing force of the polishing
tool to the peripheral portion, the feed movement of the polishing
tape, the feed speed of the polishing tape, the relative movement
of the polishing head with respect to the substrate, the relative
moving speed of the polishing head with respect to the substrate,
and the feed rate of the liquid. Moreover, the received wave
processing unit may decide whether or not the peripheral portion is
defective.
[0042] Preferably, the apparatus comprises an abnormality detecting
unit for detecting that a polish abnormality has occurred when the
polish end point is not detected even if the polishing time reaches
a predetermined maximum polishing time, and the control unit stops
the polish when the abnormality is detected by the abnormality
detecting unit. As a result, the apparatus can cope with the polish
abnormality properly.
[0043] Preferably, the apparatus comprises an abnormality detecting
unit for detecting that a polish abnormality has occurred when the
waveform of the reflected wave is abnormal, and the control unit
stops the polish when the abnormality is detected by the
abnormality detecting unit. As a result, it is possible to cope
with the polish abnormality properly.
[0044] Preferably, the apparatus comprises a tool exchange
informing unit for informing the arrival of an exchanging timing of
a polishing tool when the polishing rate obtained from the
reflected wave lowers to a predetermined tool exchanging threshold
rate. As a result, the exchanging timing can be properly informed
to promote the exchange at a proper timing.
[0045] Preferably, the wave transceiver is configured to send a
plurality of kinds of transmission waves, and the kind of the
transmission wave to be used for the measurement is changed
according to the proceeding situation of the polishing procedure
determined from the reflected wave. Here, the plurality of kinds of
transmission waves are those of at least two kinds of the
aforementioned laser light, white light, microwave, ultrasonic wave
and alternating magnetic field signal. By thus selectively using
the plurality of kinds of transmission waves, the proper
transmission waves can be used to improve the measuring
ability.
[0046] Preferably, the wave transceiver is configured to send a
plurality of kinds of transmission waves, and the kind of the
transmission wave to be used for the measurement is changed in
association with the change of the polishing condition by the
control unit. By thus changing the kinds of transmission waves
according to the polishing condition, the proper transmission waves
can be used to improve the measuring ability.
[0047] Preferably, the control unit controls the polish of the
substrate on the basis of the polishing state and the control
parameter of a peripheral portion polishing tool. Here, the control
parameter is exemplified by the torque current of the control motor
of the polishing tape. By thus utilizing the control parameter, the
polish control can be properly made.
[0048] Preferably, the control unit interchanges the control based
on the control parameter and the control based on the polishing
state, in accordance with the progress of the polishing procedure
of the substrate. For example, a coarse control is made in the
first half of the polish on the basis of the control parameter, and
a fine control is made in the second half of the polish by using
the reflected wave. Thus, the polish control can be made by using
the control parameter properly.
[0049] Preferably, the received wave processing unit detects the
polish end point by comparing the polish end point target set
according to the reflected wave at an initial polishing stage and
the reflected wave obtained from the wave transceiver. By setting
the polish end point target, the polish end point can be properly
detected.
[0050] Preferably, the apparatus comprises an end time setting unit
for setting the polish end time, at which the polish end point is
reached, on the basis of a reference time till a predetermined
reference polishing state is obtained in the polishing procedure.
As a result, the polishing time can be precisely set by using the
information on the polishing state obtained by the measurement
during the polish.
[0051] According to another aspect of the invention, there is
provided a substrate rinsing apparatus, which comprises: a
substrate holder for holding a substrate; a substrate turning unit
for turning the substrate; a liquid supply unit for supplying the
substrate with a liquid; a wave transceiver for transmitting a
transmission wave to the peripheral portion of the substrate while
the liquid is flowing on the peripheral portion, and for receiving
a reflected wave from the peripheral portion; and a received wave
processing unit for processing the signal of the reflected wave to
decide the polished state of the peripheral portion. Thus, the
aspect of the substrate rinsing apparatus can also achieve the
advantages of the invention.
[0052] According to another aspect of the invention, there is
provided a substrate peripheral portion measuring method for
measuring the state of the peripheral portion of a substrate. In
this method: a transmission wave is transmitted to the peripheral
portion while a liquid is being fed to the substrate and is flowing
on the peripheral portion; a reflected wave is received from the
peripheral portion; and the signal of the reflected wave is
processed to decide the state of the peripheral portion. Thus, the
mode of the substrate peripheral portion measuring device can also
achieve the advantages of the invention.
[0053] According to another aspect of the invention, there is
provided a substrate peripheral portion polishing method. In this
method: a substrate is held; the substrate is turned; the substrate
is supplied with a liquid; the peripheral portion of the substrate
is polished while the liquid is being supplied; a transmission wave
is transmitted to the peripheral portion while the liquid is
flowing on the peripheral portion; a reflected wave is received
from the peripheral portion; the signal of the reflected wave is
processed to decide the polished state of the peripheral portion;
and the polish of the peripheral portion is controlled in
accordance with the polished state of the peripheral portion.
[0054] According to another aspect of the invention, there is
provided a substrate peripheral portion rinsing method. In this
method: a substrate is held; the substrate is turned; the substrate
is supplied with a liquid; a transmission wave is transmitted to
the peripheral portion of the substrate while the liquid is flowing
on the peripheral portion; a reflected wave is received from the
peripheral portion; and the signal of the reflected wave is
processed to decide the polished state of the peripheral
portion.
[0055] According to the invention, as has been described
hereinbefore, the peripheral portion can be properly measured even
in the situation where the liquid flows at the peripheral portion.
For example, the peripheral portion can be properly measured midway
of the polish of the peripheral portion of the wafer substrate. By
measuring the peripheral portion during the polish, the visual
inspection and the polishing time setting work of the prior art can
be eliminated to improve the productivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] FIG. 1 is a diagram showing a substrate peripheral portion
polishing apparatus of an embodiment.
[0057] FIG. 1A is a sectional view of a peripheral portion of a
straight type wafer.
[0058] FIG. 1B is a sectional view of a peripheral portion of a
round type wafer.
[0059] FIG. 2 is a diagram showing an example of flaws of an object
to be polished.
[0060] FIG. 3 is a diagram showing a projecting/receiving unit of
the substrate peripheral portion measuring device.
[0061] FIG. 4 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0062] FIG. 5 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0063] FIG. 6 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0064] FIG. 7 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0065] FIG. 8 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0066] FIG. 9 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0067] FIG. 10 is a diagram showing a substrate peripheral portion
measuring device of another embodiment.
[0068] FIG. 11 is a diagram showing a measuring process based on
the effective amplitude of a reflected light.
[0069] FIG. 11A is a diagram showing a measuring process based on
the effective amplitude of a reflected light.
[0070] FIG. 12 is a diagram showing a measuring process based on
the frequency analyzing result of a reflected light.
[0071] FIG. 13 is a diagram showing a configuration of the case, in
which a laser light is modulated.
[0072] FIG. 14 is a diagram showing a control process of a
polishing condition.
[0073] FIG. 15 is a diagram showing a configuration of the case, in
which a plurality of kinds of transmission waves are utilized.
[0074] FIG. 16 is a diagram showing measurement zones for a zone
treatment.
[0075] FIG. 17 is a diagram showing a change in the pattern of a
reflected light.
[0076] FIG. 18 is a diagram showing a substrate treating apparatus
which is provided with the substrate peripheral portion polishing
apparatus.
[0077] FIG. 19 is a diagram showing a plating substrate treating
apparatus, which is provided with a rinsing apparatus.
[0078] FIG. 20 is a diagram showing the rinsing apparatus.
[0079] FIG. 21 is a diagram showing a CMP substrate treating
apparatus, which is provided with the rinsing apparatus.
[0080] FIG. 22 is a diagram showing plating substrate treating
apparatus, which is provided with the rinsing apparatus.
[0081] FIG. 23 is a diagram showing the measured data of an
unpolished product.
[0082] FIG. 24 is a diagram showing the measured data of a polished
product.
DETAILED DESCRIPTION
[0083] The following detailed description refers to the
accompanying drawings. The following detailed description and the
accompanying drawings do not limit the invention. Instead, the
scope of the invention is defined by the appended claims.
[0084] In the present embodiment, a substrate peripheral portion
measuring device belongs to a substrate peripheral portion
polishing apparatus for polishing the peripheral portion of a
semiconductor wafer.
[0085] In FIG. 1, a substrate peripheral portion polishing
apparatus 10 is provided with a turnable substrate holder 12. A
wafer 14 is held on the substrate holder 12. The spindle 16 of the
substrate holder 12 is connected to a motor 18. When this motor 18
rotates, the wafer 14 turns with the substrate holder 12. Above the
substrate holder 12, there is disposed a nozzle 20. This nozzle 20
is connected through a control valve 22 to a water tank 24.
[0086] As a component for polishing the peripheral portion 30 of
the wafer 14, there is disposed a polishing tape 32. This polishing
tape 32 is a polishing tool having a polishing material adhered to
the tape. This polishing tape 32 is arranged to contact with the
wafer peripheral portion 30. The polishing tape 32 is backed by a
pad 34, which is pushed by an actuator 36. This actuator 36 pushes
the pad 34 and then the polishing tape 32 onto the peripheral
portion 30 of the wafer 14. The actuator 36 is constructed of a
cylinder.
[0087] Here in this embodiment, the peripheral portion of the
substrate includes a bevel portion and an edge portion. The bevel
portion is the outer circumference of the substrate. The edge
portion is the two side portions of the bevel portion (i.e., the
end portions of the surface and the back).
[0088] FIG. 1A and FIG. 1B are enlarged sectional views of the
portions of the peripheral portions of a wafer. FIG. 1A presents a
sectional view of the so-called "straight type" wafer W having a
peripheral portion composed of a plurality of straight portions.
FIG. 1B presents a sectional view of the so-called "round type"
wafer W having a peripheral portion composed of a curved portion.
In the following description, the bevel portion of the wafer W of
FIG. 1A indicates the portion B. This portion B is composed of
upper and lower slopes P and Q sloped from the upper face and lower
face of the outer circumference of the wafer W, and a side face
portion R of the outer circumference of the wafer W. In the wafer W
of FIG. 1B, on the other hand, the bevel portion B of the wafer
indicates the portion where the section of the outer circumference
of the wafer W has a curvature. Moreover, the edge portion of the
wafer indicates the portion of an area E of FIG. 1A and FIG. 1B.
This area E is defined by the boundary of the inner side of the
bevel portion B of the wafer W and by an upper face D of the wafer
W, in which the semiconductor device is to be formed.
[0089] In the following description, the peripheral portion of the
wafer W includes the bevel portion B and the edge portion E thus
specified. In this embodiment, the bevel portion and/or the edge
portion may be polished. In the peripheral portion measurement to
be described hereinafter, too, the bevel portion and/or the edge
portion may also be measured. Here, mainly, the configuration for
polishing and measuring the bevel portion is described by way of
example.
[0090] In this embodiment, the peripheral portion is polished, and
this peripheral portion polishing is one peripheral portion
treating example. The peripheral portion treatment includes
etching. More specifically, the peripheral portion treatment
includes a bevel polishing, an edge polishing, a bevel etching and
an edge etching. Here is described the polishing treatment.
[0091] Reverting to FIG. 1, a polish controller 40 is a computer
for controlling the aforementioned substrate peripheral portion
polishing apparatus 10 as a whole. The polish controller 40 is
configured to control the motor 18, the control valve 22 and the
actuator 36.
[0092] In the entire peripheral portion polishing actions, the
polish controller 40 controls the motor 18 to turn the substrate
holder 12 together with the wafer 14. Moreover, the polish
controller 40 opens the control valve 22 to feed the (pure) water
of the water tank 24 to the upper face of the wafer 14 through the
nozzle 20. The water spreads on the upper face of the wafer 14 and
flows to the peripheral portion 30, from which it drops. In this
state, the polish controller 40 controls the actuator 36 to push
the polishing tape 32 to the peripheral portion 30 of the wafer 14.
As a result, the polishing tape 32 polishes the peripheral portion
30.
[0093] In FIG. 1, the nozzle 20 is located at the center portion of
the wafer 14 and is directed just below. However, the position and
angle of the nozzle 20 are not limited to those of FIG. 1. The
nozzle 20 may also be disposed above the wafer periphery within
such a range as can feed water necessary for the polish, for
example. Alternatively, the nozzle 20 may be inclined with respect
to the wafer 14. Then, the water may also be injected at an angle
with respect to the wafer 14.
[0094] On the other hand, FIG. 2 shows an example of flaws of the
peripheral portion to be removed in the peripheral portion
polishing treatment. In FIG. 2, for example, a wafer of 200 mm has
an entire length of a wafer outer circumference of 628 mm.
Moreover, the wafer has a flaw height (in the direction of the
wafer thickness) of 10 to 250 microns, a length (in the wafer
circumference direction) of 10 microns to 628 mm (or the entire
length) and a flaw depth of 10 to 50 microns. These flaws are
removed by the peripheral portion polishing treatment.
[0095] In the peripheral portion polishing treatment, on the other
hand, the substrate peripheral portion may have a silicon nitride
film, a silicon oxide film (SiO.sub.2 (i.e., an oxide film)), a
poly-silicon film, a barrier film of Ta, TaN, TiN, Ti or the like,
or a metal film of Cu, W or the like. These films are subjected to
the following peripheral portion measurement. By removing these
films, it is made possible to reduce the adverse affections of the
remainder of the film effectively.
[0096] Here is described a substrate peripheral portion measuring
device 50 which belongs to the substrate peripheral portion
polishing apparatus 10. The substrate peripheral portion measuring
device 50 is provided with a projecting/receiving unit 52 and a
signal processing controller 54. The projecting/receiving unit 52
is provided with a projector 56 and a receiver 58. The projector 56
projects a laser light to the peripheral portion 30 of the wafer
14. The receiver 58 receives the reflected light from the
peripheral portion 30. The projection and reception are performed
through the film of the water flowing from the peripheral portion
30.
[0097] FIG. 3 shows a configuration of the projecting/receiving
unit 52. In FIG. 3, an LD stabilizing light source device 70 (as
will be named the light source device 70) configures the projector,
and a high-speed converter 72 (as will be named the converter 72)
configures the receiver. A projecting optical fiber 74 is attached
to the light source device 70. A receiving optical fiber 76 is
attached to the converter 72. The leading ends of the projecting
optical fiber 74 and the converter 72 are held in a sensor head 78.
The laser light emitted from the light source device 70 passes
through the projecting optical fiber 74 and is projected to the
wafer 14 through the lens of the sensor head 78. The reflected
light from the wafer 14 is received by the receiving optical fiber
76, and reaches the converter 72 through the receiving optical
fiber 76. In the converter 72, the optical signal is converted into
an electric signal.
[0098] Reverting to FIG. 1, the receiver 58 converts the reflected
light into the electric signal, as described above, and feeds the
electric signal to the signal processing controller 54. This signal
processing controller 54 is a computer device, and converts the
analog signal of the reflected signal into a digital signal.
Moreover, the signal processing controller 54 processes the signal
of the reflected light to decide the state of the peripheral
portion 30 of the wafer 14. The processed result of the signal
processing controller 54 is displayed in a monitor 60 and fed to
the polish controller 40.
[0099] The signal processing controller 54 may also decide the
state of the peripheral portion 30 from the relative change of the
effective amplitude of the reflected light. The signal processing
controller 54 may further decide the state of the peripheral
portion 30 from the time-differential value of the effective
amplitude of the reflected light. The signal processing controller
54 may further decide the state of the peripheral portion 30 from
the frequency analysis result of the effective amplitude by the FFT
analysis. These parameters may be employed in combination.
[0100] Moreover, the signal processing controller 54 determines the
proceeding situation of the polishing procedure as the state of the
peripheral portion 30, and detects a polish end point. At this
polish end point, a defect or the like of the peripheral portion 30
is polished away, and the polish should be ended. The signal
processing controller 54 may also detect a minute defect in the
peripheral portion.
[0101] The processed result of the signal processing controller 54
is fed to the polish controller 40, as described above. This polish
controller 40 controls the polish on the basis of the state of the
peripheral portion 30, which is determined by the signal processing
controller 54. In this control, the polish controller 40 controls a
polishing condition. The polishing condition is a motor speed, a
water feed rate or a polishing tape pushing force. Another
polishing condition is a feed of the polishing tape, a feeding
speed of the polishing tape, a relative movement of the polishing
head with respect to the wafer, or a moving speed of the polishing
head relative to the wafer. These parameters may also be
controlled. The polishing rate is adjusted by the control of the
polishing condition.
[0102] When the signal processing controller 54 transmits the
detection of the polish end point to the polish controller 40, this
polish controller 40 ends the polish. Then, the actuator 36 is
controlled so that the polishing tape 32 is brought away from the
peripheral portion 30 of the wafer 14. The motor 18 is stopped to
stop the rotation of the wafer 14.
[Modifications]
[0103] The substrate peripheral portion polishing apparatus 10 and
the substrate peripheral portion measuring device 50 of one
embodiment of the invention have been described hereinbefore. In
this embodiment, the wafer is fed with water. However, the wafer
may also be fed with a liquid other than water.
[0104] The liquid may be any if it reduces the friction between the
polishing tape and the wafer at the polishing time and the heat
generation. Alternatively, the liquid or water may be mixed with
polishing particles for aiding the polishing ability of the
polishing tape. Likewise, the liquid may also be chemicals for
aiding in the tape polish either by removing the object by a
chemical reaction or by facilitating removal of that.
[0105] In the embodiment, on the other hand, the laser light is
projected. However, a transmission wave other than the laser light
may also be sent. However, a transmission wave other than the laser
light may be sent. For example, a white light (of halogen or
xenon), a microwave, an ultrasonic wave or an alternating magnetic
field signal may be transmitted as the transmission wave. In the
case of the halogen white light, the reflected light is condensed
for spectroscopic analyses. In the case of the microwave, the
reflected light is converted into a signal deflected from the
incident signal thereof so that the deflected signal is analyzed.
In the type of applying the alternating magnetic field, the
reflected magnetic flux from the applied signal is converted into
the impedance of an eddy-current sensor so that the converted
signal is processed for analyses. In the case of using the
microwave, on the other hand, the embodiment is provided with a
microwave waveguide. In the case of using the ultrasonic wave, the
embodiment is provided with an ultrasonic coaxial cable. In
addition, a suitable configuration for wave projections/receptions
and for signal processing may also be provided according to the
kind of the transmission wave.
[0106] In the embodiment, on the other hand, the
projecting/receiving unit is disposed at one position on the
circumference of the wafer 14. However, the projecting/receiving
unit may also be disposed at a plurality of positions. In this
case, the state of the peripheral portion 30 is determined with the
reflected waves obtained from those positions so that the
peripheral portion polish is controlled.
[0107] In this embodiment, on the other hand, the sensor head is
arranged transversely (with reference to the substrate face) of the
wafer 14 so that the projections/receptions are carried out in the
transverse direction. On the other hand, the projections/receptions
may also be carried out obliquely downward, obliquely upward,
downward or upward. Moreover, the projections/receptions may also
be carried out in a plurality of directions. For example, the
projections/receptions may further be carried out in three
directions, obliquely downward, transversely and obliquely upward.
The bevel portion and the edge portions above and below the bevel
portions can be measured independently of one another.
[0108] Here, the aforementioned various modifications can be
likewise applied even to the following other embodiments.
[0109] In addition, the signal of the reflected light disperses due
to the device difference of the projecting/receiving unit, although
not explained in the foregoing description. In order to avoid the
influence of the dispersion on the measurements, digital
amplifications, offsetting and phase processing are properly
executed on the sensor hardware unit and its controller. This
execution can reduce the influence of the device difference and can
improve the measuring precision.
[Passage Formations]
[0110] FIG. 4 and FIG. 5 show other configuration examples of the
substrate peripheral portion measuring device. As shown, a
substrate peripheral portion measuring device 80 is provided with a
passage forming member 82 in addition to the aforementioned
configuration. This passage forming member 82 has a U-shaped
sectional shape. The passage forming member 82 encloses the
peripheral portion 30 of the wafer 14 to form a passage 84 for
feeding water into the peripheral portion 30. Moreover, the passage
forming member 82 is disposed at a portion of the entire wafer
circumference. The water is fed from the nozzle 22 to the wafer 14
and flows on the upper face of the wafer 14 and into the passage
84. The water then reaches the peripheral portion 30 in the passage
84 and flows over the peripheral portion 30 and out of the passage
84.
[0111] In this embodiment, moreover, the projecting/receiving
portions of the projecting/receiving unit 52 are arranged in the
passage 84, as shown. More specifically, the (not-shown) sensor
head of the projecting/receiving unit 52 is attached to the passage
forming member 82. Moreover, the projecting optical fiber and the
receiving optical fiber are arranged in a measurement hole 88
formed in the wall face 86 of the passage forming member 82. As a
result, the projecting/receiving unit 52 projects the laser light
through the water in the passage 84 and receives the reflected
light.
[0112] Thus in the embodiment, the flow of the liquid at the
peripheral portion can be stabilized by providing the passage
forming portion. Moreover, the projections/receptions are carried
out through the stable flow so that the influence of the flow on
the projected/reflected light can be reduced to improve the
measuring ability.
[Condensation Face]
[0113] FIG. 6 shows another configuration example of the substrate
peripheral portion measuring device. Like the configurations of
FIG. 4 and FIG. 5, the substrate peripheral portion measuring
device 90 of this embodiment is provided with a passage forming
member 92. In this embodiment, moreover, the wall face 96 of the
passage 94 of the passage forming member 92 is made of a material
for reflecting the laser light. For example, the passage forming
member 92 is made of iron or glass having alumina vapor-deposited
thereon. As a result, the laser light is reflected on the wall face
96. Moreover, this wall face 96 is made of a wave-collecting face
shaped to reflect and collect the reflected light.
[0114] More specifically, the peripheral portion 30 of the wafer 14
is composed of a bevel portion 30a and upper and lower corner
portions 30b and 30c. The laser light is horizontally projected to
the wafer 14. The reflected light of the bevel portion 30a is
reflected in a horizontal direction. On the contrary, the reflected
light of the upper corner portion 30b proceeds upward and is
reflected again on the upper side portion of the wall face 96 so
that it is collected downward. On the other hand, the reflected
light of the lower corner portion 30c proceeds downward and is
reflected again on the lower side portion of the wall face 96 so
that it is collected upward.
[0115] In this embodiment, as shown, the receiving portion of the
reflected light is disposed at the position where the reflected
light is collected by the wall face 96. Specifically, the receiving
optical fibers are arranged in measuring holes 98 in the upper side
portion, the center portion and the lower side portion of the wall
face 96. These receiving optical fibers receive the individual
reflected lights of the lower corner portion 30c, the bevel portion
30a and the upper corner portion 30b.
[0116] Thus, in this embodiment, the passage wall face functions
not only to guide the liquid but also as the wave collecting face
for collecting the reflected wave. As a result, it is possible to
collect the reflected light efficiently.
[0117] Here in this embodiment, the condensation may be made within
a range so wide as is necessary for satisfying the demand for the
measuring ability. The light need not be precisely collected at one
point unlike the imaging optical system. Moreover, the condensing
unit of the wall face may be a suitable curved face such as a
semicircle or semi-ellipse.
[Water Eliminating Configuration]
[0118] FIG. 7 and FIG. 8 show another configuration example of the
substrate peripheral portion measuring device. As shown, the
substrate peripheral portion measuring device 100 is provided with
a water removing nozzle 102. This water removing nozzle 102 is
arranged in the vicinity of the peripheral portion 30 of the wafer
14. The water removing nozzle 102 injects air toward the peripheral
portion of the wafer 14 so that it blows of f and eliminates the
water of the peripheral portion 30 locally.
[0119] As shown, the projecting/receiving unit 52 is arranged to
project the laser light to the place to be cleared of water. More
specifically, the sensor head is arranged in the vicinity of the
place to be cleared of water. The projecting optical fiber and the
receiving optical fiber project/receive the light to/from the place
to be cleared of water.
[0120] Thus, this embodiment is provided with the liquid removing
unit so that it can reduce the influence of water on the
measurements thereby to improve the measuring precision.
[0121] Here, the gas to be injected by the water removing nozzle
102 is not limited to air. Specifically, the water removing nozzle
102 may inject a gas other than air, such as a nitrogen gas. The
water removing nozzle 102 may inject such a suitable gas, e.g., the
nitrogen gas or an inert gas as will not raise the problem that the
film on the wafer surface is oxidized or reduced.
[Water Blocking Configuration]
[0122] FIG. 9 and FIG. 10 show another configuration example of the
substrate peripheral portion measuring device. As shown, the
substrate peripheral portion measuring device 110 is provided with
a water blocking pad 112. This water blocking pad 112 has a shape
for enveloping the peripheral portion 30 of the wafer 14 partially.
More specifically, the water blocking pad 112 has a groove 114. The
peripheral portion 30 is so fitted in the groove 114 as to closely
contact with the inner face of the groove 114. The water blocking
pad 112 is fixed. As the wafer 14 turns, therefore, the peripheral
portion 30 of the wafer 14 slides in the groove 114.
[0123] The water blocking pad 112 is made of such a soft material
as not to damage the wafer 14. The water blocking pad 112 is also
made of such a transparent material as to transmit the laser light.
For example, the water blocking pad 112 is made of a transparent
urethane material.
[0124] In this embodiment, on the other hand, the
projecting/receiving unit 52 is arranged to project/receive the
light through the liquid blocking pad 112. More specifically, the
sensor head makes contact with the liquid blocking pad 112. The
projecting optical fiber and the receiving optical fiber are
directed toward the peripheral portion 30 through the liquid
blocking pad 112. The optical fibers may bite into the liquid
blocking pad 112.
[0125] Thus, this embodiment is provided with the liquid blocking
unit so that it can reduce the influence of water on the
measurements thereby to improve the measuring precision.
[Signal Processing (Real Data)]
[0126] Next, the processing of the signal processing controller (54
in FIG. 1) is described in more detail. The signal processing
controller converts the analog signal of the reflected light, when
it receives the analog signal from the projecting/receiving unit
52, into a digital signal. The signal processing controller
processes the signal of the digital type of the reflected light to
determine the effective amplitude. Moreover, the signal processing
controller determines the state of the peripheral portion 30 from
the real data of the effective amplitude. For example, there is
determined the relative change of the effective amplitude, from
which the proceeding situation of the polishing procedure is
monitored to detect the polish end point.
[0127] FIG. 11 shows the effective amplitude of the reflected
signal schematically. At the polish start time, the amplitude
largely changes in a portion on the circumference of the wafer. As
the polish proceeds, the peak of the amplitude becomes lower. At
the instant when the peak of the amplitude becomes equal to or
lower than a predetermined threshold value, the polish end point is
detected.
[0128] In the example of FIG. 11, the amplitude becomes even as the
polish proceeds. However, the amplitude may exhibit a reverse
tendency. In this case, the dispersion of the amplitude grows large
as the polish proceeds. The polish end point is detected when the
dispersion reaches a predetermined threshold value.
[0129] FIG. 11A shows another example. In the example of FIG. 11A,
the effective amplitude becomes large as the polish proceeds. The
polish end point is detected at the instant when the entire
effective amplitude exceeds the threshold value.
[0130] The processing of the real data is not limited to the
aforementioned examples. An arbitrary featuring event (or a
characteristic detected pattern) corresponding to the polish end
point may be specified from the real data so that the polish end
point may be detected. The usable characteristic event is
exemplified by: (1) a value no less than a predetermined value; (2)
a value no more than a predetermined value; (3) a maximum; (4) a
minimum; (5) a rise start point; (6) a rise end point; (7) a fall
start point; (8) a fall end point; (9) a value within a
predetermined gradient range; (10) a gradient maximum; or (11) a
gradient minimum. A suitable pattern may be used according to the
kind of the wafer, the state of the wafer peripheral portion or a
measurement target.
[Signal Processing (Time Differentiation)]
[0131] On the other hand, the signal processing controller may
determine the time differentiation of the effective amplitude
thereby to determine the state of the peripheral portion from the
time differentiation. In this time differentiation, the polishing
situation is grasped from the time differentiation. For example, a
pattern corresponding to a flaw is monitored. The polish end point
is detected when the flaw pattern disappears.
[0132] For the time differentiation, like the real data, the
characteristic event corresponding to the polish end time may be
extracted from the actually obtained time-differentiated data so
that the polish end point may be detected. The examples of the
characteristic event are enumerated above.
[0133] Here, the time differentiation may be of a first degree, a
second degree or a more degree. Differentiations of a plurality of
degrees may be used together.
[Signal Processing (Frequency Analysis)]
[0134] The signal processing controller may also subject the
effective amplitude to the FFT processing for the frequency
analysis. In this case, the proceeding situation of the polishing
procedure is monitored from the frequency analysis result to detect
the polish end point.
[0135] FIG. 12 shows one example of the frequency analysis result
schematically. In this example, the level of a frequency (e.g., a
left-hand peak) is kept as the polish proceeds, but the level of
another frequency (e.g., three right-hand peaks) lowers as the
polish proceeds. Therefore, the polishing procedure is monitored on
the basis of the latter frequency. The polish end point is detected
at the instant when the level of the noted frequency lowers to a
predetermined threshold level.
[0136] In the example of FIG. 12, the levels of some frequencies
drop as the polish proceeds. As the polish proceeds, on the
contrary, the levels of some frequencies can rise. Moreover, the
levels of all frequencies can also rise. In these cases, the state
of the peripheral portion can be likewise detected from the result
of the frequency analysis.
[Signal Processing (Integration)]
[0137] On the other hand, the signal processing controller may also
perform a processing to integrate the effective amplitude. In this
case, the signal processing controller integrates the signals of
the reflected wave, which are obtained along the wafer
circumference as the wafer turns. From the integration result, the
polished state is determined, and the polish end point is detected.
In this case, too, the characteristic event corresponding to the
polish end point is extracted from the integration result.
[Signal Processing/Defect Detection]
[0138] In the foregoing various processing operations, the
polishing procedure is monitored, and the polish end point is
detected. In addition, the signal processing controller may also
detect a defect. Preferably, a characteristic portion indicating a
minute defect is extracted from the signal of a reflected wave. The
characteristic portion of the minute defect may be extracted from
any of the aforementioned real data, the time differentiation, the
frequency analysis result or the integration result. A signal
indicating the defect occurrence is displayed in the monitor.
[0139] Preferably, the signal processing controller acquires the
reference (or position) of the wafer from the notch of the wafer,
the orientation flat and the signal difference of the remaining
portions. Moreover, the signal processing controller acquires
information on the turning angle of the wafer. This turning angle
of the wafer may be acquired from the angle of rotation of the
motor. Moreover, the signal processing controller determines the
position of a defect on the basis of the turning angle of the
wafer. The position of the defect is expressed by that on the wafer
circumference. The position of the defect is also displayed as a
portion of the defect information in the monitor.
[Signal Processing/Noise Elimination]
[0140] The signal processing controller is configured to eliminate
noise components from the signal of the reflected light. For
example, the signal processing controller determines the noise
components by the FFT signal analysis. In accordance with the noise
components specified, the signal processing controller sets the
cut-off frequency of a noise eliminating filter. The adjustment of
the cut-off frequency is suitably made in the setting of the recipe
of a control unit. The filter is exemplified by an LPF (Low Pass
Filter), a BPF (Band Pass Filter), an HPF (High Pass Filter) or a
notch filter. Filters of a plurality of kinds may also be used
together. The filter may also be realized by an analog circuit or
by a digital processing.
[0141] By thus eliminating the noise components, it is possible to
acquire the signal indicating the state of the peripheral portion
precisely and stably, to specify the state of the peripheral
portion precisely and to detect the polish end point precisely.
[Setting of Beam Size]
[0142] Here in this embodiment, the beam size of the laser light is
set in the following manner. The wafer moves to some extent in the
horizontal direction and in the vertical direction while it is
turning. In order that the detection sensitivity may not lower even
with the movement of the wafer, the beam size is set according to
the movement of the work. As a result, the laser light is converged
within the moving range of the work. In other words, the laser
light irradiates the peripheral portion of the work properly, even
if the work moves within that moving range. The beam size is
adjusted by the control for focusing the light source.
[0143] In case a minute defect is to be detected, for example, the
beam size is set to 10 microns.times.1,000 microns. The figure of
10 microns is a transverse beam size, and the figure of 1,000
microns is a longitudinal (i.e., the direction of the wafer
thickness) beam size. By applying these beam sizes, the defect can
be detected even if the wafer moves up and down. Moreover, the
transverse beam size is made small, the quantity of light increases
to retain the sensitivity for detecting the minute defect.
[0144] When the homogeneity of the surface of the wafer peripheral
portion is to be measured, for example, the beam is made circular
to have a beam diameter of 1 to 2 mm. As a result, the measurement
of the entire peripheral portion can be effectively made even if
the wafer moves. Because of the homogeneity measurement, moreover,
a sufficient performance can be attained even for the large beam
size.
[0145] Thus in this embodiment, the state of the peripheral portion
of the wafer can be precisely measured by setting the beam size
according to the movement of the wafer, even if the wafer moves to
some extent while it is turning.
[Modulation of Laser Light]
[0146] In this embodiment, on the other hand, the laser light is
properly modulated, as described in the following.
[0147] With reference to FIG. 13, in this embodiment, a pulse
modulation is carried out in a laser light source 120. For example,
a coherence light source is used, and a pulse modulation of 34 kHz
is carried out (although not limited to 34 kHz). As a result, a
pulsating laser light is projected on the wafer. A photodiode 122
also receives a pulsating reflected light. The photodiode 122
converts the reflected light into an electric signal. This electric
signal is fed to a synchronism detector 124. This synchronism
detector 124 is fed with information on the modulation from the
laser light source 120. The synchronism detector 124 subjects the
signal of the reflected light to a synchronous detection. The
synchronously detected signal is fed to the signal processing
controller 54.
[0148] Thus, this embodiment modulates the laser light. The laser
light is modulated, and only the peripheral portion polishing
signal is highly sensitively extracted while eliminating the
remaining noise signals, thereby to raise the S/N ratio. As a
result, the measurement sensitivity can be augmented to improve the
measuring ability.
[Polish Control]
[0149] Next, the polish control based on the measurement result of
the peripheral portion is described in more detail. This control is
made by the polish controller (40 of FIG. 1).
[0150] The polish controller controls the substrate peripheral
portion polishing apparatus, when the polish end point is detected,
to end the polish, as has already been described. During the
polish, the polish controller also controls the polishing actions
of the substrate peripheral portion polishing apparatus in
accordance with the peripheral portion measurement result. Here is
carried out the closed loop control.
[0151] The object of the control is the wafer turning motor, the
water feeding control valve, and the polishing tape pushing
actuator. The polish controller controls at least one of the
turning speed of the wafer, the pushing force of the polishing tool
to the peripheral portion, the feed movement of the polishing tape,
the feed speed of the polishing tape, the relative movement of the
polishing head with respect to the substrate, the relative moving
speed of the polishing head with respect to the wafer, and the feed
rate of water. By this control, the polishing speed (or the
polishing rate) is adjusted. When the motor speed is raised, for
example, the polishing speed is raised. When the tape pushing force
is raised, moreover, the polishing speed is raised. These factors
may be simultaneously controlled in association. Alternatively, the
factors may also be controlled only partially.
[0152] FIG. 14 shows an example of a preferable polish control. It
is assumed that the peripheral portion polish is performed to
expose the silicon film of the wafer to the outside and to smoothen
the peripheral portion surface. In FIG. 14, the abscissa indicates
the time, and the ordinate indicates a parameter of the polishing
state. This parameter is exemplified by the range (i.e., the
difference between the maximum and the minimum) of the effective
amplitude of the reflected light.
[0153] The polish controller causes the polish in a high-speed mode
till the parameter of the polishing state reaches a predetermined
value P1. Specifically, the motor and so on are controlled so that
the polishing speed may take a predetermined high value. When the
parameter reaches the value P1 at a time t1, the polishing speed is
switched to a low-speed mode for the polish. The motor and so on
are controlled so that the polishing speed may take a predetermined
value lower than the high-speed mode. When the parameter of the
polishing state reaches a value P2 corresponding to the polish end
point, the polish controller ends the polish. At this time, the
peripheral portion of the wafer is cleared of the unnecessary film
or the like so that the silicon face appears with a smooth
surface.
[0154] Thus, this embodiment can control the polish properly on the
basis of the measured state of the peripheral portion. Moreover,
the polishing condition can be effectively changed by controlling
at least one of the turning speed of the substrate, the pushing
force of the polishing tool to the peripheral portion, the feed
movement of the polishing tape, the feed speed of the polishing
tape, the relative movement of the polishing head with respect to
the substrate, the relative moving speed of the polishing head with
respect to the substrate, and the feed rate of a liquid. Moreover,
the polishing speed can be raised within a proper range on the
basis of the measurement result thereby to shorten the polishing
time period.
[Abnormality Detection (Excess of Polishing Time)]
[0155] Here is described an abnormality detecting function of this
embodiment. This function is realized by the signal processing
controller 54 of FIG. 1. This signal processing controller 54
receives the information of the polish start from the polish
controller 40, and monitors the lapse time from the polish start.
The signal processing controller 54 decides whether or not a
predetermined maximum polishing time period has elapsed from the
polish start. This maximum polish time is preset and stored in the
signal processing controller 54.
[0156] In case the polish is being normally carried out, the polish
end point is detected before the maximum polishing time period
elapses. In case the polish end point is not detected even if the
maximum polishing time period elapses, it is deemed that some
abnormality has occurred. This abnormality can be exemplified by a
trouble in the polishing apparatus or in the measuring device.
[0157] The signal processing controller 54 decides that a polishing
abnormality has occurred, if the polish end point is not detected
even when the polishing time period reached the maximum polishing
time. The signal processing controller 54 sends a signal indicating
the occurrence of an abnormality to the polish controller 40. This
polish controller 40 controls the motor and so on, when it receives
the signal indicating the abnormality occurrence, to stop the
polish forcibly. On the other hand, the signal processing
controller displays the abnormality occurrence on the monitor
60.
[0158] Thus, according to this embodiment, the polishing
abnormality can be properly coped with.
[Abnormality Detection (Abnormality Signal)]
[0159] Here is described another abnormality detecting function. In
this detecting function, the signal processing controller 54
decides that the polishing abnormality has occurred, if the signal
waveform of the reflected light is abnormal. In this processing,
the signal processing controller 54 is stored with the information
indicating the standard state of the signal waveform of the
reflected light. The signal processing controller 54 decides
whether or not the waveform of the reflected light obtained by the
measurement has deviated from the standard state. When the actual
waveform deviates the standard state, the signal processing
controller 54 decides that the abnormality has occurred.
[0160] The abnormality occurrence is displayed in the monitor 60
and transmitted to the polish controller 40. This polish controller
40 controls the motor and so on to stop the polish forcibly.
[0161] Thus, this embodiment can cope with the polishing
abnormality properly.
[0162] Here have been described the abnormality detections of two
kinds (i.e., the abnormality detection due to the excess of the
polishing time period, and the abnormality detection due to the
abnormal signal). These abnormality detections may be separately
used according to the state of the wafer peripheral portion of the
object to be measured. One of abnormality detections may also be
made according to the state of the wafer peripheral portion.
[Report of Timing for Tool Exchange]
[0163] Here is described a function to report the time for a tool
exchange in this embodiment. This function is realized by the
signal processing controller 54. The signal processing controller
54 monitors the polishing rate obtained from the information on the
reflected wave. Here, the signal processing controller 54 receives
the information on the polish start from the polish controller 40.
On the other hand, the signal processing controller 54 detects the
polish end point from the signal of the reflected wave. Moreover,
the signal processing controller 54 calculates the polishing rate
from the time period from the polish start to the polish end
point.
[0164] The signal processing controller 54 monitors the polishing
rate thus obtained. The polishing rate lowers as a number of wafers
are treated. The signal processing controller 54 reports the
arrival of the exchanging time of the polishing tool, when the
polishing rate drops to a predetermined tool exchanging threshold
rate. Here, the signal processing controller 54 displays an image
indicating the tool exchanging timing on the monitor 60.
[0165] Thus, according to this embodiment, the exchanging timing
can be properly reported to promote the exchange of the tool at a
proper timing.
[0166] In this embodiment, the polishing time period may also be
monitored. This polishing time period corresponds to the polishing
rate so that the polishing rate can also be monitored by monitoring
the polishing time period.
[0167] In case the polishing condition is adjusted by the polish
controller, it is preferred to monitor the change in the polishing
rate in consideration of the polishing condition.
[Combination of Transmission Waves of a Plurality of Kinds]
[0168] Here is described a preferred configuration example for
combining transmission waves of a plurality of kinds. In the
description thus far made, the transmission wave is mainly the
laser light. In this embodiment, on the contrary, the transmission
waves of a plurality of kinds are combined. One of these
transmission waves may naturally be the laser light.
[0169] FIG. 15 shows a substrate peripheral portion polishing
apparatus of this embodiment schematically. In the substrate
peripheral portion polishing apparatus 130, a wave transceiver unit
132 is composed of a first wave transceiver 132a and a second wave
transceiver 132b. The first wave transceiver 132a performs the
projection/reception of the first transmission wave, and the second
wave transceiver 132b performs the transmission/reception of the
second transmission wave. The first transmission wave and the
second transmission wave are exemplified by a laser light, a white
light, a microwave, an ultrasonic wave or an alternating magnetic
field signal. The first transmission wave and the second
transmission wave are of different kinds. In case the transmission
wave is the laser light, the wave transceiver unit is the
aforementioned projecting/receiving unit.
[0170] A signal processing controller 134 receives the electric
signal of the first reflected wave corresponding to the first
transmission wave, from the first wave transceiver 132a, and
processes the signal of the first reflected wave to determine the
state of the wafer peripheral portion. Moreover, the signal
processing controller 134 receives the electric signal of the
second reflected wave corresponding to the second transmission
wave, from the second wave transceiver 132b, and processes the
signal of the second reflected wave to determine the state of the
wafer peripheral portion.
[0171] The signal processing controller 134 controls the first wave
transceiver 132a and the second wave transceiver 132b to cause
either of them to perform the wave transmission/reception.
Moreover, the signal processing controller 134 processes the signal
obtained from one of the first wave transceiver 132a and the second
wave transceiver 132b, to detect the state of the peripheral
portion. As a result, the first transmission wave and the second
transmission wave are selectively utilized.
[0172] The signal processing controller 134 may also cause both the
first wave transceiver 132a and the second wave transceiver 132b to
perform the wave transmission/reception. Moreover, the signal
processing controller 134 may also determine the state of the wafer
peripheral portion from the signal which is obtained from one of
the first wave transceiver 132a and the second wave transceiver
132b. In this case, too, the first transmission wave and the second
transmission wave are selectively utilized.
[0173] Here is described the mode of switching the transmission
wave to be used for the measurement. Here are described three
preferred patterns.
(1) In the first pattern, the signal processing controller 134
changes the kind of the transmission wave in accordance with the
material of the peripheral portion of the wafer to be measured. As
a result, the transmission wave suited for the material of the
peripheral portion can be used to improve the measurement
sensitivity and the measuring ability. (2) In the second pattern,
the signal processing controller 134 changes the kind of the
transmission wave to be used in the measurement, in accordance with
the proceeding situation of the polishing procedure. The proceeding
situation of the polishing procedure is obtained from the signal of
the reflected wave. In this embodiment, one transmission wave is
used in the first half of the polish, and the other transmission
wave is used in the second half of the polish.
[0174] When the polish is started, more specifically, one
transmission wave is used to monitor the state of the wafer
peripheral portion. When the wafer peripheral portion comes into a
predetermined state, the transmission wave to be used for the
measurement is interchanged. Then, the state of the wafer
peripheral portion is monitored with the other transmission wave,
and the polish end point is detected.
[0175] By thus changing the kind of the transmission wave in
accordance with the progress of the polish, the proper transmission
wave can be used to improve the measurement sensitivity and the
measuring ability.
(3) In the third pattern, the signal processing controller 134
changes the kind of the transmission wave in accordance with the
polishing condition. The information on the polishing condition is
fed from the polish controller 136 to the signal processing
controller 134. For example, it is assumed that the high-speed mode
and the low-speed mode are set as the polishing condition. The
high-speed mode is set in the first half of the polish, and the
low-speed mode is set in the second half of the polish.
[0176] In this case, the signal processing controller 134 changes
the kind of the transmission wave when the polishing condition
changes. In a multi-step polish for which a plurality of polishing
conditions are set, therefore, the transmission wave to be used for
the measurement is interchanged in association with the polishing
condition.
[0177] In this embodiment, by thus changing the kind of the
transmission wave in accordance with the polishing condition, a
proper transmission wave can be used to improve the measurement
sensitivity and the measuring ability.
[0178] In the foregoing description, the transmission waves of two
kinds are used. On the contrary, it is natural that transmission
waves of three kinds or more can be used. It is also natural that a
plurality of wave transceivers can be disposed for the transmission
waves of the individual kinds. In the foregoing description, the
three patterns are explained. Of these three, two or more patterns
may also be suitably combined.
[Joint Use of Peripheral Portion Measurement and Control Parameter
of Polishing Tool]
[0179] Here is described a proper embodiment, in which the
peripheral portion measurement and the control parameter of the
polishing tool are jointly used. In the foregoing embodiment, as
described with reference to FIG. 1, the polishing tool is the
polishing tape 32, which is pushed to the wafer 14 by the actuator
36, and this actuator 36 is made of the cylinder. In this
embodiment, on the contrary, the actuator 36 is provided with a
control motor. In this case, the torque current of the control
motor can be used as the control parameter of the polishing tool.
In this embodiment, moreover, the polish is controlled by using the
torque current and the peripheral portion measurement result.
[0180] In this embodiment, more specifically, when the polish is
started, the polish controller 40 monitors the torque current. When
the torque current reaches a predetermined threshold value, the
polish controller 40 instructs the signal processing controller 54
of the start of measurement. In accordance with this instruction,
the signal processing controller 54 starts the measurement with the
signal obtained from the projecting/receiving unit 52. Moreover,
the signal processing controller 54 informs the polish controller
40 of the detection of the polish end point when it detects the
polish end point. The polish controller 40 controls the motor and
so on to end the polish.
[0181] Thus, in this embodiment, the substrate polish is controlled
on the basis of the polishing state and the control parameter of
the polishing tool, so that the polish can be properly controlled
by using the control parameter.
[0182] In this embodiment, on the other hand, the control based on
the control parameter and the control based on the polishing state
are interchanged according to the progress of the substrate
polishing procedure. In the aforementioned example, a coarse
control is made in the first half of the polish on the basis of the
control parameter, and a fine control is made in the second half of
the Polish by using the reflected wave. Thus, the polish control
can be made by using the control parameter properly.
[0183] In this embodiment, too, transmission waves of a plurality
of kinds may be selectively used as in the foregoing embodiment.
These transmission waves may also be used together with the control
parameter of the polishing tool.
[Zone Treatment]
[0184] Here is described a preferred embodiment for the zone
treatment. This zone treatment is realized by a signal processing
controller.
[0185] In the zone treatment, as referred to FIG. 16, a plurality
of measurement zones are provided along the outer circumference of
the wafer when the signal of the laser reflected light is to be
processed. In the shown example, the wafer outer circumference is
divided into five measurement zones. In the zone treatment,
moreover, zone data are determined from the measurement zones. The
zone data represent the signals of reflected lights obtained from
the measurement zones. Moreover, these zone data are used to
determine the state of the wafer peripheral portion.
[0186] In this embodiment, the wafer is turned, but the
projecting/receiving unit is fixed. As the wafer is turned,
therefore, the reflected light is obtained from the entire
circumference of the wafer. The data of the entire zone are divided
into the data of a plurality of zones.
[0187] The boundaries of the measurement zones may be either at
arbitrary positions on the wafer outer circumference or at preset
positions. In this latter case, the signal processing controller
acquires information on the wafer turning angle thereby to
determine the positions of the boundaries from the information on
the wafer turning angle. The reference of the wafer turning angle
is exemplified by the positions of notches.
[0188] The zone data represent the signals of reflected lights
obtained from the measurement zones, as described hereinbefore. The
zone data are exemplified by the average value, the maximum, the
level difference (or range) and the like of the effective
amplitudes of the reflected lights in the measurement zones.
Moreover, the zone data may be expressed by the time
differentiations of the effective amplitudes of the reflected
lights in the measurement zones, and the time differentiations may
be of a first degree, a second degree or more degrees.
[0189] The zone data of all measurement zones may be used for
processing them. There may also be used the zone data of one or
more predetermined measurement zones. There may also be used the
zone data of one or more arbitrarily selected measurement
zones.
[0190] The zone data are compared with a preset designated value so
that the polish end point is detected. When the zone data come into
a predetermined designated range, for example, the polish end point
is detected. The polish end point is also detected, when the zone
data become a predetermined designated value or higher.
Alternatively, the polish end point may also be detected when the
zone data become a predetermined designated value or lower.
[0191] In the zone data processing, the following zone converging
operation may also be preferably carried out. In the zone
converging operation, the zone data of a plurality of measurement
zones are compared.
[0192] In the zone converging operation, one measurement zone is
designated. It is then decided whether or not the difference in the
zone data between the designated zone and the remaining zones is at
a predetermined threshold value or smaller. The polish end point is
detected when the difference in the zone data is at the threshold
value or smaller. In the zone converging operation, the zone data
may represent the effective amplitudes of the measurement zones or
may be the time differentiation.
[0193] In this embodiment thus far described, the state of the
substrate peripheral portion can be properly grasped by using the
zone data thereby to improve the measuring ability.
[0194] By comparing the zone data of the measurement zones,
moreover, the situation of the peripheral portion can be grasped
with reference to the measurement zones so that the detection
sensitivity of the state of the peripheral portion is improved. As
a result, the state of the substrate peripheral portion can be
properly grasped to improve the measuring ability.
[Target Setting Operation]
[0195] In addition, the substrate peripheral portion measuring
device of this embodiment may also set the target of the polish end
point thereby to perform the measurements with the set target, as
described in the following.
[0196] In this operation, the signal processing controller
determines the remaining amount of polish from the signal of the
reflected light obtained at the initial stage of the polish, and
sets the target of the polish end point. This polish end point
target indicates the reflected light, which is obtained when the
polish of the remaining amount is ended so that the wafer
peripheral portion becomes smooth. The remaining amount of polish
and the target of the polish end point are expressed by the
effective amplitude of the reflected light, for example.
[0197] The signal processing controller holds and uses the target
of the polish end point to detect the polish end point. Here, the
signal of the reflected wave inputted is compared with the target
of the polish end point. This polish end point is detected when the
input signal reaches the target of the polish end point. The polish
controller is informed of the polish end point to end the
polish.
[0198] Thus, this embodiment can detect the polish end point
properly by setting the target of the polish end point.
[End time Setting Operation]
[0199] On the other hand, the substrate peripheral portion
measuring device of this embodiment may also be configured to set
the polish end time, as described in the following.
[0200] In this operation, there is determined at first the
reference time t1 till the predetermined reference polished state
is obtained in the polishing procedure. An auxiliary time ta is
calculated from the reference time t1 and a predetermined
coefficient k1. For example, ta=t1.times.k1. The auxiliary time ta
is calculated by ta=t1.times.k1, ta=t1/k1, ta=t1+k1, ta=t1-k1 and
so on. The auxiliary time ta is a time period from the reference
time t1 to the polish end point. Therefore, a polish end time t2
(i.e., the time period from the polish START TIME to the polish end
time) is expressed by t1+ta. The additional polish is carried from
the reference time t1 to the polish end time t2.
[0201] The polish end time t2 is sent from the signal processing
controller to the polish controller so that it is applied for
controlling the polish in the polish controller. In this
embodiment, the polish end time t2 is properly set by using a
sample wafer. The polish end time t2 is held in the polish
controller and is applied, after the sample wafer is processed, for
treating a plurality of wafers.
[0202] Thus, in this embodiment, the polishing time can be
precisely set by using the information on the polishing state
obtained by the measurements during the polish. Moreover, the
polishing time can be simply set.
[0203] The target setting operation and the end time setting
operation have thus far been described. Either the polishing ending
target or the polish end time may also be set depending on the
material of the wafer to be treated. Alternatively, operation may
be carried out by using both of them, and either setting time
(i.e., an earlier time or a later time) may also be set as the end
time, if necessary.
[Use of Relation Between Peripheral Portion Material and
Reflection]
[0204] On the other hand, the substrate peripheral portion
measuring device of this embodiment may also decide the state of
the wafer peripheral portion on the basis of the change in the
reflection according to the material change of the surface of the
peripheral portion of the wafer accompanying the treatment of the
wafer, as described in the following example.
[0205] Here, it is assumed that the silicon nitride (SiN) film of
the peripheral portion of a silicon (Si) wafer is removed. Silicon
and silicon nitride are different in the absorption wavelength
characteristics as optical characteristics. The silicon nitride
film absorbs a wavelength of 320 nm or less. On the contrary, the
silicon wafer reflects the whole wavelength.
[0206] It is, therefore, set that the wavelength of the laser light
is absorbed by the silicon nitride film. The wavelength of the
laser light is set to 240 to 320 nm, for example.
[0207] At the initial stage of the polish, the silicon nitride film
exists on the wafer surface so that the optical reflection is low.
As the polish of the peripheral portion proceeds, the material of
the wafer surfaces changes from the silicon nitride into the
silicon. When this silicon appears, the quantity of the reflected
light abruptly rises. This optical change is detected by the signal
processing controller. The polish end point is detected when a
predetermined optical change appears. This optical change is so
prominent that the end point is precisely detected.
[0208] Thus, noting the change in the reflection according to the
change in the material of the surface of the peripheral portion,
the state of the peripheral portion can be precisely decided to
improve the measuring ability.
[Use of Relation Between Peripheral Portion Material and Reflection
Pattern]
[0209] On the other hand, the substrate peripheral portion
measuring device of this embodiment may also decide the state of
the peripheral portion on the basis of the change in the reflected
pattern according to the material change of the surface of the
peripheral portion accompanying the treatment of the wafer, as
described in the following example.
[0210] When the output of the laser light is properly adjusted, a
pattern appears in the reflected light. In this embodiment, this
reflected pattern is used.
[0211] Here, it is assumed that the silicon nitride film (SiN) is
removed from the peripheral portion of the silicon wafer (Si). As
the polish proceeds, the silicon nitride film is removed to expose
the silicon wafer to the outside.
[0212] With the irradiation of a collimated laser beam of a
specific wavelength, as shown in FIG. 17, a significant difference
appears in the reflected pattern between the silicon nitride film
(unpolished) and the silicon (polished). On the silicon nitride
film, a fringe pattern appears in the reflected pattern due to the
diffraction of the film edge. On the contrary, no fringe pattern
appears in the reflected pattern from the polished face of the
silicon. This change in the pattern is detected.
[0213] For the pattern detection, the signal of the reflected
pattern is subjected to an IV conversion (i.e., a current-voltage
conversion) by a photodiode in the projecting/receiving unit.
Alternatively, this projecting/receiving unit may be provided with
a high-speed image taking device. This image taking device (or an
image pickup device) is provided with a CCD or CMOS camera, for
example. The pattern thus obtained is subjected to a pattern
recognition treatment. In the example described, the polish end
point is detected when the fringe pattern in the pattern
disappears.
[0214] Thus in this embodiment, by noting the change in the
reflected pattern in accordance with the material change of the
surface of the peripheral portion, the state of the peripheral
portion can be precisely decided to improve the measuring
ability.
[0215] Thus, it is possible to use the change in the reflection and
the change in the reflected pattern. The reflection or the
reflected pattern may be separately used according to the state of
the wafer peripheral portion of the object to be measured.
[Substrate Treating Apparatus with Substrate Peripheral Portion
Polishing Apparatus]
[0216] Next, FIG. 18 shows an example of the substrate treating
apparatus which is provided with the substrate peripheral portion
polishing apparatus of this embodiment. The substrate treating
apparatus 200 is provided with a load/unload unit 202, a first
transfer robot 204, a substrate stage 206 (or a buffer), a second
transfer robot 208, a notch polishing module 210, a bevel polishing
module 212, a primary rinsing module 214 and a secondary rinsing
module 216.
[0217] The wafer is transferred by the first transfer robot 204
from the load/unload unit 202 to the substrate stage 206. Then, the
wafer is sequentially transferred by the second transfer robot 208
to the notch polishing module 210, the bevel polishing module 212,
the primary rinsing module 214 and the secondary rinsing module
216. The first transfer robot 204 returns the rinsed wafer to the
load/unload unit 202.
[0218] In FIG. 18, the bevel polishing module 212 corresponds to
the substrate peripheral portion polishing apparatus thus far
described. The substrate peripheral portion measuring device of
this embodiment also belongs to the bevel polishing module 212.
[0219] In an applied example of this embodiment, moreover, the
wafer evaluating face is set on the end face or back face of the
wafer. The evaluation is timed during or after the polish. For this
evaluation, the polished state during the polish is monitored, the
polish end point during the polish is detected, or the
presence/absence of a defect in the polished wafer is decided. In
the monitor of the polished state of the defected portion, for
example, the end face polish is interrupted at a stage midway of
the end face polish, and the wafer is saved. The remaining defect
(or the residual of the defect polish) is measured. The necessary
time for the additional polish is calculated from the measurement
result so that the additional polish is performed. The wafer is
moved again from the polish position to the saving position (as
indicated at 206 in FIG. 18) for the measurement so that the
remaining polish is measured. Thus, a series of operations are
carried out by an initial polish, a measurement at the saving
position, an additional polish, a re-save, a re-measurement and an
additional polish. The measurement and the additional polish may be
repeated. The peripheral portion is polished by those series
operations. The polish time can also be determined.
[Application to Rinsing Apparatus (for Rinsing after Plating)]
[0220] Here is described an embodiment for incorporating the
substrate peripheral portion measuring device into the rinsing
apparatus. In the description thus far made, the substrate
peripheral portion measuring device is incorporated into the
substrate peripheral portion polishing apparatus. In the following
description, on the other hand, the substrate peripheral portion
measuring device is incorporated into the rinsing apparatus. This
rinsing apparatus is exemplified by a rinsing apparatus related to
a plating operation, a rinsing apparatus related a CMP
(Chemical-Mechanical Polish), and a rinsing apparatus related to an
etching operation. The defect and unnecessary substance of the
peripheral portion can be detected by measuring the peripheral
portion with the rinsing apparatus.
[0221] FIG. 19 shows a plating substrate treating apparatus. This
substrate treating apparatus 220 is provided with a substrate
cassette 222, a first transfer robot 224, a substrate stage 226 (or
a temporary stage), a second transfer robot 228, a plating bath
230, a rinsing apparatus 232, a rinsing liquid and chemicals supply
device 234, a plating chemicals supply device 236, a control unit
238 and a display unit 240.
[0222] The substrate is transferred by the first transfer robot 224
from the substrate cassette 222 to the substrate stage 226. The
substrate is further transferred by the second transfer robot 228
to the plating bath 230 and the rinsing apparatus 232. The plating
bath 230 is supplied with the plating chemicals from the plating
chemicals supply device 236. On the other hand, the rinsing
apparatus 232 is supplied with the chemicals and the rinsing liquid
from the rinsing liquid and chemicals supply device 234. The
rinsing treatment and the drying treatment are carried out in the
rinsing apparatus 232. The substrate rinsed is returned to the
substrate cassette 222.
[0223] In the configuration of FIG. 19, the rinsing apparatus 232
is preferably provided with the substrate peripheral portion
measuring device. In the rinsing apparatus 232, the turning wafer
is fed with the rinsing liquid as in the ordinary rinsing
apparatus. In this state, the substrate peripheral portion
measuring device is provided for measuring the wafer peripheral
portion.
[0224] FIG. 20 shows an example of the configuration of the rinsing
apparatus 232. In this rinsing apparatus 232, a base unit 250 holds
a wafer 252. On the other hand, the base unit 250 is supported by a
shaft 254 so that it turns together with the wafer 252.
[0225] The base unit 250 is provided with a wafer holding member.
As shown, this wafer holding member is turnably supported by a
turning pin. This turning pin pivots the portion of the wafer
holding member above the center of gravity. The wafer holding
member is so arranged as is made parallel to the shaft 254 by its
own weight when the wafer stands still. As the shaft 254 turns, a
centrifugal force occurs in the wafer holding member. By this
centrifugal force, the lower portion (i.e., the portion of the
wafer holding member below the turning pin) is moved outward and is
raised. As a result, the upper portion (i.e., the portion of the
wafer holding member above the turning pin) falls down inward to
hold and grip the wafer. At least three wafer holding portions are
disposed in the circumferential direction.
[0226] The wafer 252 is fed on its surface with a rinsing liquid
from a rinsing liquid feeding nozzle 256 and with chemicals from a
chemicals feeding nozzle 258. The rinsing liquid feeding nozzle 256
is supplied with the rinsing liquid from a rinsing line supply line
260, and the chemicals feeding nozzle 258 is supplied with the
chemicals from a chemicals supply line 262. Moreover, the wafer
turns and liquid supply are controlled by a control unit 264, which
is connected with a display input unit 266.
[0227] Typically in the rinsing apparatus of FIG. 20, the rinsing
liquid is water (or pure water) or gas-dissolved water. The rinsing
apparatus is properly provided with a peripheral portion measuring
device for measuring the peripheral portion while being fed with
the rinsing liquid. The peripheral portion measuring device may
measure the peripheral portion when the chemicals are fed.
[Application to Rinsing Apparatus (Rinsing after CMP)]
[0228] FIG. 21 shows a CMP substrate treating apparatus. This
substrate treating apparatus 270 is provided with a substrate
cassette 272, a first transfer robot 274, a substrate stage 276 (or
a temporary stage), a second transfer robot 278, a polishing module
280, a rinsing apparatus 282, a rinsing liquid and chemicals supply
device 284, a slurry supply device 286, a control unit 288 and a
display unit 290.
[0229] The substrate is transferred by the first transfer robot 274
from the substrate cassette 272 to the substrate stage 276. The
substrate is further transferred by the second transfer robot 278
sequentially to the polishing module 280 and the rinsing apparatus
282. The polishing module 280 is supplied with the slurry from the
slurry supply device 286. On the other hand, the rinsing apparatus
282 is supplied with the chemicals and the rinsing liquid from the
rinsing liquid and chemicals supply device 284. The rinsing
apparatus 282 performs the rinsing operation with the chemicals and
the drying operation. The substrate rinsed is returned to the
substrate cassette 272.
[0230] In the configuration of FIG. 21, the rinsing apparatus 282
is properly provided with the substrate peripheral portion
measuring device. In the rinsing apparatus 282, as in the ordinary
rinsing apparatus, the turning wafer is fed thereon with the
rinsing liquid. The substrate peripheral portion measuring device
is provided for measuring the wafer peripheral portion in that
state. The configuration of rinsing apparatus may be one shown in
FIG. 20.
[Application to Rinsing Apparatus (Rinsing after Etching)]
[0231] FIG. 22 shows a plating substrate treating apparatus. This
substrate treating apparatus 300 is used for forming fine copper
wiring over the substrate. The substrate treating apparatus 300 is
provided with a substrate load/unload unit 302, a first transfer
robot 304, a substrate stage 306, a second transfer robot 308, a
plating device 310, a bevel etching device 312, a rinsing apparatus
314, a heat treating (annealing) device 316, a plating liquid tank
318 and a plating liquid analyzing device 320.
[0232] The substrate is transferred by the first transfer robot 304
from the substrate cassette of the substrate load/unload unit 302
to the substrate stage 306. The substrate is further transferred by
the second transfer robot 308 sequentially to the plating device
310 and the bevel etching device 312.
[0233] The bevel etching device 312 subjects the substrate
peripheral portion to an etching treatment. In the bevel etching
device 312, for example, the substrate is continuously fed, while
being held horizontally and turned, at the central portion on its
surface side with an acid solution. The substrate is continuously
or intermittently fed at its circumferential peripheral portion
with an oxidizer solution.
[0234] The acid solution may be a non-oxidizing acid such as
hydrofluoric acid, hydrochloric acid, sulfuric acid, citric acid or
oxalic acid. The oxidizer solution used is any of ozone water, an
aqueous solution of hydrogen peroxide, an aqueous solution of
nitric acid and an aqueous solution of hypochlorous acid. These may
be used in combination. Copper or the like is filmed on or stuck to
the circumferential peripheral portion of the substrate. Such
copper or the like is abruptly oxidized in the oxidizer solution,
and is etched and dissolved with the oxide solution fed from the
central portion of the substrate so that it is removed. The oxide
solution spreads from the substrate center over the entire
surface.
[0235] After bevel-etched, the substrate is transferred by the
second transfer robot 308 to the rinsing apparatus 314. In this
rinsing apparatus 314, the surface of the substrate is rinsed with
the chemicals or the rinsing water such as pure water, and is
subjected to a spin drying treatment.
[0236] Then, the substrate is further transferred to the heat
treating device 316. After the heat treatment in the heat treating
device 316, the substrate is transferred by the second transfer
robot 308 to the substrate stage 306. Moreover, the substrate is
returned by the first transfer robot 304 to the substrate
load/unload unit 302.
[0237] In the configuration of FIG. 22, the rinsing apparatus 314
is properly provided with the substrate peripheral portion
measuring device. In the rinsing apparatus 314, the turning wafer
is fed with the rinsing liquid. The substrate peripheral portion
measuring device is provided for measuring the wafer peripheral
portion in this state. By this peripheral portion measurement, it
is inspected whether or not the portion is left unetched.
[0238] In case the unetched portion is detected by the peripheral
portion measurement, on the other hand, the wafer may be
transferred to the bevel etching device 312 and returned to the
etching step. At another step, on the other hand, the unetched
portion may be removed. The re-treatment or the like according to
the measurement result at such rinsing step may also be carried out
in the aforementioned other embodiments.
[Other Modes]
[0239] In the peripheral portion polishing substrate treating
apparatus 200, as shown in FIG. 18, the bevel polishing module 212
acting as the substrate peripheral portion polishing apparatus is
provided with the substrate peripheral portion measuring device. On
the contrary, the substrate peripheral portion measuring device may
also be disposed in the notch polishing module 210. On the other
hand, the substrate peripheral portion measuring device may also be
disposed in the primary rinsing module 214 or the secondary rinsing
module 216 acting as the rinsing apparatus. In this modification,
the polish is once ended, and the peripheral portion is measured at
the rinsing step. If a re-polish is necessary, the wafer is
returned to the polishing step.
[0240] In the bevel etching substrate treating apparatus 300, as
shown in FIG. 22, the rinsing apparatus 314 is provided with the
substrate peripheral portion measuring device. On the contrary, the
substrate peripheral portion measuring device may also belong to
the bevel etching device 312. In this case, the peripheral portion
is measured during the etching operation. The peripheral portion is
measured while the wafer is being fed with the etching chemicals in
place of the water. Moreover, the peripheral portion may also be
measured after having been cleared of the chemicals, as has been
described in the foregoing embodiment.
[0241] As exemplified in those examples, the peripheral portion
measuring device may also be disposed in the etching or polishing
removing apparatus so that it may measure the peripheral portion
during the removing operation thereby to detect the end point or
the like. Moreover, the peripheral portion measuring device may
also be disposed in the rinsing apparatus which is provided
together with the aforementioned removing apparatus so that it may
perform the measurement while the removing treatment being
interrupted.
[0242] In addition, the substrate peripheral portion measuring
device may also be disposed in another apparatus. Moreover, the
substrate peripheral portion measuring device may be solely
disposed. In this modification, the substrate is held and turned
for the measurement, and the wafer is fed with a liquid (e.g.,
water) for the measurement.
[0243] The invention has been described in connection with its
preferred embodiments. However, the invention should not be limited
to the aforementioned embodiments but could naturally be modified
within the scope of the invention by those skilled in the art.
EXAMPLES
[0244] FIG. 23 and FIG. 24 show the experimental data obtained by
using the measuring device of the invention. The experimental data
of FIG. 23 and FIG. 24 are the results of measurements using the
laser beam, as shown in the embodiment of FIG. 3. FIG. 23 shows the
measurement data of an unpolished product, and FIG. 24 shows the
measurement data of a polished product.
[0245] In FIG. 23 and FIG. 24, the ordinate indicates the voltage
at the time when the reflected light is expressed in terms of a DC
voltage. One scale corresponds to 2 volts. The abscissa indicates
the position in the circumferential direction of the wafer. The
drawings show the data at the time when the wafer starts from the
notch portion and returns after four turns to the notch portion. In
other words, the whole range in the abscissa direction corresponds
to the four circumferences of the wafer. 2.5 scales in the abscissa
direction corresponds to one circumference of the wafer.
[0246] FIG. 23 shows the measurement data of the unpolished
product, as described above. In the measurements, a pulsating laser
light is projected from the optical fiber, and the reflected light
is received by the optical fiber.
[0247] In FIG. 23, the quantity of the reflected light is small
over a wide range. This indicates that the peripheral portion of
the wafer is covered with the film of silicon nitride (SiN).
[0248] In FIG. 23, moreover, high spike signals are found. In some
portions, the intensities of the reflected light are locally high.
These portions indicate that the wafer is locally polished. At
these portions, the wafer peripheral portion is polished for
experiments so that the silicon nitride is damaged to expose the
silicon (Si) locally to the outside. The exposure of silicon raises
the intensities of the reflected signal.
[0249] FIG. 24 shows the measurement data of the polished article.
In FIG. 24, the quantity of reflected light is large over a wide
range. This indicates that the film of the silicon nitride of the
wafer peripheral portion is polished away to expose the silicon
(Si) to the outside. Observing the damaged portions in FIG. 23, the
silicon nitride around the damage is removed so that the damage
disappears.
[0250] By comparing the reflected lights before and after the
polish, as shown in FIG. 23 and FIG. 24, it is possible to detect
the polish end point (i.e., the end of the polish). For deciding
the polish end point, as has already been described, it is
arbitrary to use the change of a relative optical quantity, the
change of an absolute value or the change of a differentiated
value.
[0251] While there has been described what is at present considered
to be preferred embodiments of the invention, it will be understood
that various modifications may be made thereto, and it is intended
that appended claims cover all such modifications as fall within
the true spirit and scope of the invention.
INDUSTRIAL APPLICABILITY
[0252] The invention can measure the peripheral portion of a
substrate and can be usefully employed in substrate manufacturing
facilities.
* * * * *