U.S. patent application number 17/378994 was filed with the patent office on 2021-11-04 for laser annealing apparatus, inspection method of substrate with crystallized film, and manufacturing method of semiconductor device.
The applicant listed for this patent is THE JAPAN STEEL WORKS, LTD.. Invention is credited to Suk-Hwan CHUNG, Masashi MACHIDA, Kenichi OHMORI, Ryosuke SATO.
Application Number | 20210343531 17/378994 |
Document ID | / |
Family ID | 1000005725169 |
Filed Date | 2021-11-04 |
United States Patent
Application |
20210343531 |
Kind Code |
A1 |
OHMORI; Kenichi ; et
al. |
November 4, 2021 |
LASER ANNEALING APPARATUS, INSPECTION METHOD OF SUBSTRATE WITH
CRYSTALLIZED FILM, AND MANUFACTURING METHOD OF SEMICONDUCTOR
DEVICE
Abstract
A laser annealing apparatus (1) according to the embodiment
includes: a laser beam source (11) configured to emit a laser beam
(L1) to crystallize an amorphous silicon film (101a) on a substrate
(100) and to form a poly-silicon film (101b); a projection lens
(13) configured to condense the laser beam to irradiate a silicon
film (101); a probe beam source configured to emit a probe beam
(L2); a photodetector (25) configured to detect the probe beam (L3)
transmitted through the silicon film (101), a processing apparatus
(26) configured to calculate a standard deviation of detection
values of a detection signal output from the photodetector, and to
determine a crystalline state of the crystallized film based on the
standard deviation.
Inventors: |
OHMORI; Kenichi;
(Yokohama-shi, JP) ; CHUNG; Suk-Hwan;
(Yokohama-shi, JP) ; SATO; Ryosuke; (Yokohama-shi,
JP) ; MACHIDA; Masashi; (Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE JAPAN STEEL WORKS, LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
1000005725169 |
Appl. No.: |
17/378994 |
Filed: |
July 19, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16320455 |
Jan 24, 2019 |
11114300 |
|
|
PCT/JP2017/025652 |
Jul 14, 2017 |
|
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17378994 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/2011 20130101;
H01L 21/02675 20130101; H01L 29/78663 20130101; H01L 21/268
20130101 |
International
Class: |
H01L 21/20 20060101
H01L021/20; H01L 21/02 20060101 H01L021/02; H01L 29/786 20060101
H01L029/786; H01L 21/268 20060101 H01L021/268 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2016 |
JP |
2016-163693 |
Jun 7, 2017 |
JP |
2017-112516 |
Claims
1-26. (canceled)
27. A laser annealing apparatus comprising: a laser beam source
configured to emit a laser beam to crystallize an amorphous film
over a substrate and to form a crystallized film; a projection lens
configured to condense the laser beam to irradiate the amorphous
film; a probe beam source configured to emit a probe beam; a
photodetector configured to detect the probe beam transmitted
through the crystallized film; a conveying path configured to
convey the substrate to change an irradiation position of the laser
beam onto the substrate; and a processing unit configured to change
an irradiation position of the probe beam onto the substrate, to
calculate a standard deviation of detection values of a detection
signal output from the photodetector, and to determine a
crystalline state of the crystallized film based on the standard
deviation.
28. The laser annealing apparatus according to claim 27, wherein
the processing unit is configured to: compare the standard
deviation with a threshold; and determine the substrate to be
non-defective when the standard deviation is less than the
threshold or determine the substrate to be defective when the
standard deviation is equal to or greater than the threshold.
29. The laser annealing apparatus according to claim 27, wherein
the processing unit configured to determine the crystalline state
based on an average value of the detection values.
30. The laser annealing apparatus according to claim 27, wherein
the projection lens is configured to cause the laser beam to form a
linear irradiation region on the amorphous film, and the
photodetector is configured to detect the probe beam having passed
through the projection lens.
31. The laser annealing apparatus according to claim 27, further
comprising: a cylindrical lens configured to cause the probe beam
to form a linear illumination region on the crystallized film; and
a condenser lens configured to condense the probe beam transmitted
through the crystallized film on the photodetector.
32. The laser annealing apparatus according to claim 27, wherein
the conveying path is configured to convey the substrate while the
substrate is being irradiated simultaneously with the laser beam
and the probe beam.
33. The laser annealing apparatus according to claim 27, wherein
the conveying path comprises a gas-floating unit configured to jet
gas to the substrate to float the substrate.
34. The laser annealing apparatus according to claim 27, further
comprising a stage configured to hold the substrate, wherein the
stage is configured to be moved to convey the substrate along the
conveying path, the laser annealing apparatus comprises a
carrying-out port which a conveying robot that carries the
substrate out from the stage enters, and the irradiation position
of the probe beam onto the substrate is changed by the conveying
robot carrying the substrate out from the stage.
35. The laser annealing apparatus according to claim 34, wherein
the photodetector is configured to detect the probe beam having
passed through the crystallized film twice or more.
36. A laser annealing apparatus comprising: a laser beam source
configured to emit a laser beam to crystallize an amorphous film
over a substrate and to form a crystallized film; a projection lens
configured to condense the laser beam to irradiate the amorphous
film; a stage configured to convey the substrate to change an
irradiation position of the laser beam onto the substrate; a probe
beam source configured to emit a probe beam; a photodetector
configured to detect the probe beam transmitted through the
crystallized film outside the stage during a conveying robot takes
out the substrate from the stage; and a processing unit configured
to determine a crystalline state of the crystallized film based on
a detection signal output from the photodetector.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a laser annealing
apparatus, an inspection method of a substrate with crystalized
film and a manufacturing method of a semiconductor device.
BACKGROUND ART
[0002] Patent Literature 1 discloses a laser annealing apparatus
for forming a polysilicon thin film. The laser annealing apparatus
in Patent Literature 1 irradiates a polysilicon thin film with
evaluating light to evaluate the crystalline state of the
polysilicon thin film. Then, the laser annealing apparatus detects
the irradiation light transmitted through the polysilicon thin
film. The crystalline state is evaluated based on the ratio of the
transmission intensity of the irradiation light to the light
intensity of reference light which is emitted from the same light
source and is not transmitted through the polysilicon thin
film.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Patent No. 2916452
SUMMARY OF INVENTION
Technical Problem
[0004] However, the laser annealing apparatus in Patent Literature
1 cannot properly evaluate a crystalline state.
[0005] Other problems and novel features will be clarified from the
description of this specification and the attached drawings.
Solution to Problem
[0006] According to an embodiment, an inspection method of a
substrate with a crystalized film, the method includes the steps
of: (C) detecting, by a photodetector, the probe beam transmitted
through the crystallized film; (D) changing an irradiation position
of the probe beam on the crystallized film to acquire a plurality
of detection values of a detection signal from the photodetector;
and (E) determining, based on a standard deviation of the plurality
of detection values, a crystalline state of the crystallized
film.
[0007] According to an embodiment, manufacturing method of a
semiconductor device, the method includes the steps of: (b)
irradiating the amorphous film with a laser beam to crystallize the
amorphous film and to form a crystallized film; (c) irradiating the
crystallized film with a probe beam; (d) detecting, by a
photodetector, the probe beam transmitted through the crystallized
film; (e) changing an irradiation position of the probe beam on the
crystallized film to acquire a plurality of detection values of a
detection signal output from the photodetector; and (f)
determining, based on a standard deviation of the plurality of
detection values, a crystalline state of the crystallized film.
[0008] According to an embodiment, a laser annealing apparatus
includes: a laser beam source configured to emit a laser beam to
crystallize an amorphous film over a substrate and to form a
crystallized film; a probe beam source configured to emit a probe
beam; a photodetector configured to detect the probe beam
transmitted through the crystallized film; and a processing unit
configured to change an irradiation position of the probe beam on
the substrate, to calculate a standard deviation of detection
values of a detection signal output from the photodetector, and to
determine a crystalline state of the crystallized film based on the
standard deviation.
[0009] According to an embodiment, a laser annealing apparatus
includes: a stage configured to convey the substrate; a probe beam
source configured to emit a probe beam that enters the substrate
outside of the stage; and a photodetector configured to detect the
probe beam transmitted through the crystallized film outside the
stage during a conveying robot takes out the substrate from the
stage.
Advantageous Effects of Invention
[0010] According to the embodiment, it is possible to properly
evaluate the crystalline state of a crystallized film.
BRIEF DESCRIPTION OF DRAWINGS
[0011] FIG. 1 is a diagram showing an optical system of a laser
annealing apparatus according to the present embodiment.
[0012] FIG. 2 is a perspective view for explaining a laser beam and
a probe beam that enter a substrate in the laser annealing
apparatus.
[0013] FIG. 3 is a diagram for explaining a laser beam and a probe
beam that enter a substrate.
[0014] FIG. 4 is a diagram showing a probe beam that enters a
substrate.
[0015] FIG. 5 is a flowchart showing an inspection method according
to an embodiment.
[0016] FIG. 6 is a graph showing detection values in a
condition-setting substrate.
[0017] FIG. 7 is a graph showing the average values and the
standard deviations of detection values in a condition-setting
substrate.
[0018] FIG. 8 is a diagram showing the captured images and the
standard deviations of three substrates.
[0019] FIG. 9 is a flowchart showing a method for forming a
polysilicon film using an ELA apparatus according to the present
embodiment.
[0020] FIG. 10 is a diagram showing an apparatus layout including
the ELA apparatus according to the present embodiment.
[0021] FIG. 11 is a flowchart showing a method for forming a
polysilicon film using an ELA apparatus according to a comparison
example.
[0022] FIG. 12 is a diagram showing an apparatus layout including
the ELA apparatus according to the comparison example.
[0023] FIG. 13 is a plan view schematically showing a configuration
of an ELA apparatus according to a second embodiment.
[0024] FIG. 14 is a side view schematically showing the
configuration of the ELA apparatus according to the second
embodiment.
[0025] FIG. 15 is a diagram showing a configuration for a laser
beam and a probe beam to enter a substrate from the same side.
[0026] FIG. 16 is a cross-sectional view of a simplified
configuration of an organic EL display.
[0027] FIG. 17 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0028] FIG. 18 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0029] FIG. 19 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0030] FIG. 20 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0031] [FIG. 21] FIG. 20 is a cross-sectional view showing a
process in a manufacturing method of a semiconductor device
according to the present embodiment.
[0032] FIG. 22 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0033] FIG. 23 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0034] FIG. 24 is a cross-sectional view showing a process in a
manufacturing method of a semiconductor device according to the
present embodiment.
[0035] FIG. 25 is a flowchart showing a method for determining the
optimized energy density of a laser beam in an inspection method
according to the present embodiment.
[0036] FIG. 26 is a diagram for explaining the region of the
substrate in the flowchart shown in FIG. 25.
[0037] FIG. 27 is a side view schematically showing the
configuration of the ELA apparatus according to a third
embodiment.
[0038] FIG. 28 is a plan view schematically showing a configuration
of an ELA apparatus according to the third embodiment.
[0039] FIG. 29 is a diagram showing the size of a probe beam
according to a Z position.
[0040] FIG. 30 is a diagram showing an example of an optical system
for a probe beam in an ELA apparatus.
[0041] FIG. 31 is a diagram showing an example of an optical system
for a probe beam in an ELA apparatus.
[0042] FIG. 32 is a diagram showing an example of an optical system
for a probe beam in an ELA apparatus.
[0043] FIG. 33 is a graph showing a measurement result of a probe
beam.
DESCRIPTION OF EMBODIMENTS
First Embodiment
[0044] A laser annealing apparatus according to the present
embodiment is, for example, an excimer laser anneal (ELA) apparatus
that forms low temperature poly-silicon (LTPS) films. Hereinafter,
a laser annealing apparatus, and an inspection method and a
manufacturing method of a semiconductor device according to the
present embodiment are described with reference to the
drawings.
[0045] (Optical System of ELA Apparatus)
[0046] A configuration of an ELA apparatus 1 according to the
present embodiment is described with reference to FIG. 1. FIG. 1 is
a diagram schematically showing an optical system of the ELA
apparatus 1. The ELA apparatus 1 irradiates a silicon film 101
formed on a substrate 100 with a laser beam L1. This converts an
amorphous silicon film (a-Si film) 101 into a polysilicon film
(p-Si film) 101. The substrate 100 is, for example, a transparent
substrate such as a glass substrate.
[0047] Note that, an XYZ three-dimensional orthogonal coordinate
system is shown in FIG. 1 to clarify the description. The Z
direction is the vertical direction and perpendicular to the
substrate 100. The XY plane is parallel to the surface of the
substrate 100 on which the silicon film 101 is formed. The X
direction is the longitudinal direction of the rectangular
substrate 100, and the Y direction is the latitudinal direction of
the substrate 100. In the ELA apparatus 1, the silicon film 101 is
irradiated with the laser beam L1 while the substrate 100 is being
conveyed in the +X direction with a conveyance mechanism (not
shown) such as a stage. With regard to the silicon film 101 in FIG.
1, the silicon film 101 before the irradiation with the laser beam
L1 is referred to as an amorphous silicon film 101a, and the
silicon film 101 after the irradiation with the laser beam L1 is
referred to as a polysilicon film 101b.
[0048] The ELA apparatus 1 includes an annealing optical system 10,
an illumination optical system 20, and a detection optical system
30. The annealing optical system 10 irradiates the silicon film 101
with the laser beam L1 for crystallizing the amorphous silicon film
101a. The illumination optical system 20 and the detection optical
system 30 evaluate ununiformity in the crystalline state of the
substrate 100.
[0049] Specifically, the ELA apparatus 1 includes a laser beam
source 11, a mirror 12, a projection lens 13, a probe beam source
21, a mirror 22, a lens 23, a condenser lens 24, a photodetector
25, and a processing apparatus 26.
[0050] First, the annealing optical system 10 that irradiates the
silicon film 101 with the laser beam L1 is described. The annealing
optical system 10 is disposed above the substrate 100 (at the +Z
side). The laser beam source 11 is, for example, an excimer laser
beam source that emits an excimer laser beam having a center
wavelength of 308 nm. The laser beam source 11 emits a pulsed laser
beam L1. The laser beam source 11 emits the laser beam L1 toward
the mirror 12.
[0051] The mirror 12 and the projection lens 13 are disposed above
the substrate 100. The mirror 12 is a dichroic mirror that
selectively transmits light according to, for example, a
wavelength. The mirror 12 reflects the laser beam L1.
[0052] The laser beam L1 is reflected by the mirror 12 and enters
the projection lens 13. The projection lens 13 includes a plurality
of lens for projecting the laser beam L1 on the substrate 100, that
is, on the silicon film 101.
[0053] The projection lens 13 condenses the laser beam L1 on the
substrate 100. Here, the shape of an irradiation region P1 of the
laser beam L1 on the substrate 100 is described with reference to
FIG. 2. The laser beam L1 forms a linear irradiation region P1
along the Y direction on the substrate 100. That is, the laser beam
L1 is a line beam having its longitudinal direction in the Y
direction on the substrate 100. The silicon film 101 is irradiated
with the laser beam L1 while the substrate 100 is being conveyed in
the +X direction. Thus, a belt-shaped region having the length of
the irradiation region P1 in the Y direction as its width can be
irradiated with the laser beam L1.
[0054] Next, the illumination optical system 20 that irradiates the
substrate 100 with a probe beam L2 is described with reference to
FIG. 1. The illumination optical system 20 is disposed under the
substrate 100 (at the -Z side). The probe beam source 21 emits a
probe beam L2 having a different wavelength from the laser beam L1.
For example, a continuous wave (CW) semiconductor laser beam source
or the like can be used as the probe beam source 21. The center
wavelength of the probe beam L2 is, for example, 401 nm. The
wavelength of the probe beam L2 is preferably a wavelength with a
low absorption rate at the silicon film 101. Thus, it is preferable
that a laser beam source, a light emitting diode (LED) light
source, or the like that emits monochromatic light is used as the
probe beam source 21.
[0055] The probe beam source 21 emits the probe beam L2 toward the
mirror 22. The mirror 22 reflects the probe beam L2 toward the lens
23. The lens 23 condenses the probe beam L2 on the silicon film
101. As shown in FIG. 2, a cylindrical lens can be used as the lens
23. Accordingly, the probe beam L2 forms a linear illumination
region P2 along the Y direction on the substrate 100 (the silicon
film 101). That is, the probe beam L2 is a line beam having its
longitudinal direction in the Y direction on the substrate 100. In
addition, the length of the illumination region P2 in the Y
direction is shorter than the irradiation region P1.
[0056] The illumination region P2 of the probe beam L2 is disposed
at the +X side compared to the irradiation region P1 of the laser
beam L1. That is, the probe beam L2 enters the substrate 100 at an
upper stream side in the conveying direction of the substrate 100
than the irradiation region P1 of the laser beam L1. Accordingly,
the crystallized polysilicon film 101b is irradiated with the probe
beam L2 as shown in FIG. 1.
[0057] Next, the detection optical system 30 that guides a probe
beam L3 transmitted through the silicon film 101 to the
photodetector 25 is described. The detection optical system 30 is
disposed above the substrate 100. Note that, FIG. 1 shows the probe
beam transmitted through the silicon film 101 as the probe beam L3.
The transmittance of the silicon film 101 to a probe beam varies
according to the crystalline state of silicon.
[0058] The probe beam L3 transmitted through the silicon film 101
enters the projection lens 13. The probe beam L3 refracted by the
projection lens 13 enters the mirror 12. Note that, the mirror 12
is a dichroic mirror that transmits or reflects light according to
a wavelength as described above. The mirror 12 transmits the probe
beam L3 having the wavelength of 401 nm and reflects the laser beam
L1 having the wavelength of 308 nm. Thus, the probe beam L3 is
branched from the optical path of the laser beam L1. The mirror 12
serves as a light branching means for branching the optical path of
the laser beam L1 and the optical path of the probe beam L3
according to a wavelength.
[0059] The probe beam L3 having passed through the mirror 12 enters
the condenser lens 24. The condenser lens 24 condenses the probe
beam L3 on the light-receiving surface of the photodetector 25. The
photodetector 25 is, for example, a photo diode and detects the
probe beam L3. The photodetector 25 outputs a detection signal
according to the detection light amount of the probe beam L3 to the
processing apparatus 26. The detection value of the detection
signal corresponds to the transmittance of the silicon film 101. In
addition, since the substrate 100 is conveyed in the +X direction
at a constant speed, the photodetector 25 detects the profile of
the detection light amount in the X direction (that is, the
transmittance of the silicon film 101).
[0060] The processing apparatus 26 is an operation unit that
performs predetermined operation to the detection value of the
detection signal. Note that, the processing apparatus 26 may
includes an A/D converter that A/D-converts an analogue detection
signal into a digital detection value. Alternatively, the
photodetector 25 may includes an A/D converter that A/D-converts an
analogue detection signal into a digital detection value.
[0061] While scanning the substrate 100 in the +X direction, the
photodetector 25 detects the probe beam L3. Thus, the processing
apparatus 26 acquires a plurality of detection values according to
the sampling rate of the photodetector 25 or the A/D converter. The
processing apparatus 26 includes a memory that stores the detection
values. Since the substrate 100 is scanned in the +X direction at a
constant speed, the detection values indicate the profile of the
transmittance in the X direction. If the crystalline state of the
silicon film 101 is ununiform, different detection values according
to the illumination positions are acquired. If the crystalline
state of the silicon film 101 is uniform, the detection values are
substantially the same value.
[0062] The processing apparatus 26 determines the quality of the
substrate 100 based on the standard deviation of the detection
values. That is, when the standard deviation is less than a preset
threshold, the processing apparatus 26 determines that the
ununiformity in the crystalline state is small. In this case, the
processing apparatus 26 that the polysilicon film 101b is formed
uniformly and that the substrate 100 is non-defective. On the other
hand, when the standard deviation is equal to or greater than the
preset threshold, the processing apparatus 26 determines that the
ununiformity in the crystalline state is large. In this case, the
processing apparatus 26 determines that the polysilicon film with
large ununiformity is formed and that the substrate 100 is
defective. The processing of the processing apparatus 26 is to be
described later.
[0063] With reference to FIGS. 3 and 4, the illumination region P2
of the probe beam L2 on the substrate 100 is described. FIG. 3 is
an XY plan view showing examples of the illumination region P2 of
the probe beam L2 and the irradiation region P1 of the laser beam
L1. FIG. 4 shows the probe beam L2 measured by a beam profiler.
[0064] As shown in FIG. 3, the width of the irradiation region P1
in the X direction is 400 .mu.m. In addition, a gap of 100 .mu.m is
provided between the irradiation region P1 and the illumination
region P2 in the X direction. The length of the irradiation region
P1 in the Y direction is longer than the length of the illumination
region P2. As shown in FIG. 4, the length of the illumination
region P2 in the Y direction is 6 mm. The maximum width of the
illumination region P2 in the X direction is 17 Note that, when the
irradiation region P1 is smaller than the size of the substrate 100
in the Y direction, the substrate 100 is moved in the Y direction
to perform annealing treatment. Accordingly, a silicon film 100 is
crystallized on the entire substrate 100.
[0065] Here, it is assumed that the conveyance speed of the
substrate 100 in the X direction is 12 mm/sec. Furthermore, it is
assumed that the condensed size of the illumination region P2 is 17
.mu.m, and that the measurement overlap is set to 50% (=8.5 .mu.m).
The sampling rate required in this case is 12000/8.5=1.411 kHz.
Note that, the measurement overlap defines the size of the
overlapped illumination region P2 between the two consecutive
detection values. That is, the region overlapped by 8.5 .mu.m is
irradiated with the illumination region P2 corresponding to the
first detection value and the illumination region P2 corresponding
to the second detection value.
[0066] Next, an inspection method according to the present
embodiment is described with reference to FIG. 5. FIG. 5 is a
flowchart showing the inspection method according to the present
embodiment.
[0067] First, when annealing treatment is performed to the silicon
film 101, the processing apparatus 26 acquires n numbers of
detection values V.sub.1, V.sub.2, . . . , V.sub.n (S11). Here, n
is an integer of 2 or more. As the illumination position of the
probe beam L2 is changed in the X direction, the detection values
V.sub.1 to V.sub.n are detected. For example, the detection value
when the illumination position on the substrate 100 in the X
direction is X.sub.1 is V.sub.1, and the detection value when the
illumination position on the substrate 100 in the X direction is
X.sub.2 is V.sub.2. The detection value when the illumination
position on the substrate 100 in the X direction is X.sub.n is
V.sub.n. In this manner, the photodetector 25 detects a detection
value according to an illumination position in the X direction. As
the illumination position onto the substrate 100 is changed by the
substrate conveyance, the processing apparatus 26 acquires the
detection values V.sub.1 to V.sub.n.
[0068] Then, the processing apparatus 26 calculates an average
value V.sub.average and a standard deviation .sigma. of the
detection values V.sub.1 to V.sub.n (S12). Specifically, a
processor or an operation circuit provided to the processing
apparatus 26 calculates the average value V.sub.average and the
standard deviation .sigma. based on the expressions shown in FIG.
5.
[0069] The processing apparatus 26 determines whether the
calculated standard deviation .sigma. is less than a threshold
.sigma..sub..alpha. (S13). That is, the processing apparatus 26
compares the standard deviation .sigma. with the preset threshold
.sigma..sub..alpha.. Then, when the standard deviation .sigma. is
less than the threshold .sigma..sub..alpha. (YES in S13), the
processing apparatus 26 determines the substrate 100 to be
non-defective, and the treatment is terminated. On the other hand,
when the standard deviation .sigma. is equal to or greater than the
threshold .sigma..sub..alpha. (NO in S13), the processing apparatus
26 determines the substrate 100 to be defective, and returns to the
annealing treatment. Accordingly, re-annealing treatment is
performed to the defective substrate 100.
[0070] In the re-annealing treatment, the entire surface of the
substrate 100 is irradiated with the laser beam L1 similarly to the
first annealing treatment. In the re-annealing treatment, the
substrate 100 is irradiated with the laser beam L1 having a weaker
irradiation intensity than that in the first annealing treatment.
The portion where the irradiation light amount of the laser beam L1
has been insufficient to be adequately crystallized can be
certainly crystallized. In addition, the photodetector 25 may
detect the probe beam L3, and the processing apparatus 26 may
determine the crystalline state similarly in the re-annealing
treatment.
[0071] Furthermore, the substrate 100 may be partially irradiated
with the laser beam L1 in the re-annealing treatment. It is thereby
possible to shorten the time required for the re-annealing
treatment. For example, the measurement range is divided into ten,
and the processing apparatus 26 calculates ten standard deviations
.sigma..sub.1 to .sigma..sub.10. Then, the portions having large
standard deviations among the standard deviations .sigma..sub.1 to
.sigma..sub.10 may be irradiated with the laser beam L1. For this
reason, the processing apparatus 26 compares each of the standard
deviations .sigma..sub.1 to .sigma..sub.10 with the threshold
.sigma..sub..alpha. to obtain the portions having standard
deviations greater than the threshold .sigma..sub..alpha.. Then,
the portions having the standard deviations greater than the
threshold .sigma..sub..alpha. are irradiated with the laser beam
L1. In other words, the portions having the standard deviations
less than the threshold .sigma..sub..alpha. are not irradiated with
the laser beam L1. It is obvious that the number of divisions of
the substrate 100 is not limited to ten, and the number is only
required to be two or more.
[0072] In the present embodiment, the quality determination based
on the average value V.sub.average is performed in S13 in addition
to the quality determination based on the standard deviation
.sigma.. That is, the average value is added to the evaluation
items as well as the standard deviation. Then, when either of the
standard deviation or the average value does not meet the
criterion, the processing apparatus 26 determines the substrate 100
to be defective. Note that, the quality determination based on the
average value V.sub.average may not be performed. In this case, the
processing apparatus 26 is only required to calculate the standard
deviation .sigma. without calculating the average value
V.sub.average in step S12.
[0073] Specifically, it is determined whether the average value
V.sub.average is less than a threshold V.sub..alpha. (S13). That
is, the processing apparatus 26 compares the average value
V.sub.average with the preset threshold V.sub..alpha.. Then, when
the average value V.sub.average is greater than the threshold
V.sub..alpha. (YES in S13), the processing apparatus 26 determines
the substrate 100 to be non-defective and terminates the treatment.
On the other hand, when the average value V.sub.average is equal to
or less than the threshold V.sub..alpha. (YES in S13), the
processing apparatus 26 determines the substrate 100 to be
defective and returns to the annealing treatment. In this manner,
by performing the quality determination based on both of the
standard deviation .sigma. and the average value V.sub.average, it
is possible to more properly evaluate the crystalline state. Thus,
it is possible to improve the accuracy of the quality
determination. Then, the laser annealing apparatus 1 performs
re-annealing treatment to the substrate 100 determined to be
defective. Accordingly, it is possible to certainly crystallize the
portion where the irradiation light amount of the laser beam L1 has
been insufficient to be adequately crystallized. Thus, it is
possible to improve the ununiformity in the crystalline state.
[0074] In this manner, the photodetector 25 detects the probe beam
L3 transmitted through the substrate 100 in the present embodiment.
Since the probe beam L3 is detected at different illumination
positions by the photodetector 25, the processing apparatus 26
acquires a plurality of detection values. The processing apparatus
26 performs the quality determination based on the standard
deviation of the detection values. It is thereby possible to
properly evaluate ununiformity in the polysilicon film 101b. Thus,
it is possible to further improve the accuracy of the quality
determination. Especially when the laser beam L1 is a linear pulsed
laser beam, stripes of light and darkness along the line (also
referred to as shot unevenness) can appear on the silicon film 101.
It is possible for the ELA apparatus 1 according to the present
embodiment to reduce the shot unevenness.
[0075] In the present embodiment, by adding not only the standard
deviation .sigma. of the detection values but also the average
value V.sub.average to the evaluation items, it is possible to
further improve the accuracy of the quality determination. In
addition, the re-annealing treatment is performed to the substrate
100 determined to be defective. It is possible to certainly
crystallize the portion where the irradiation light amount of the
laser beam L1 has been insufficient to be adequately crystallized.
Thus, it is possible to improve the yield and to increase the
productivity.
[0076] Furthermore, while a substrate is being conveyed by a stage
or the like, the substrate 100 is irradiated simultaneously with
the laser beam L1 and the probe beam L2. It is thereby possible to
detect the probe beam L3 transmitted through the silicon film 101
during laser annealing. Thus, it is possible to determine whether
the state of the surface of the silicon film 101 is optimal in a
short time.
[0077] In the present embodiment, the illumination region P2 of the
probe beam L2 is disposed in the vicinity of the irradiation region
P1 of the laser beam L1. Accordingly, it is possible to evaluate
the crystalline state of the silicon film 101 immediately after
being crystallized. Thus, it is possible to evaluate ununiformity
in the crystalline state of the silicon film 101 substantially on
time and to improve the accuracy of the quality determination.
[0078] In addition, the photodetector 25 detects the probe beam
having passed through the projection lens 13 in order to bring the
illumination region P2 of the probe beam L2 closer to the
irradiation region P1 of the laser beam L1. In other words, the
projection lens 13 is disposed in the optical path from the probe
beam source 21 to the photodetector 25. The projection lens 13 is
shared by the annealing optical system 10 and the illumination
optical system 20. Accordingly, it is possible to bring the
illumination region P2 closer to the irradiation region P1 on the
substrate 100.
[0079] In the present embodiment, the substrate 100 is irradiated
with the linear illumination region P2. Thus, it is possible to
reduce the influence of small dirt, dust, or the like. For example,
in the case of the irradiation with a point-like illumination
region, if dirt or the like is attached to the illumination region,
the transmittance is greatly lowered. In this case, the detection
value at the portion to which the dirt or the like is attached is
greatly lowered, and the standard deviation becomes larger. On the
other hand, by the irradiation with the linear illumination region
P2 as described in the present embodiment, it is possible to reduce
the influence of small dirt or the like. That is, since the region
having a wide width in the Y direction is irradiated, it is
possible to improve the accuracy of the quality determination
compared with the irradiation with a point-like illumination
region. Furthermore, since the illumination region P2 is parallel
to the linear irradiation region P1, it is possible to properly
evaluate shot unevenness which is stripes of light and darkness
along the Y direction.
[0080] In the present embodiment, the condenser lens 24 is disposed
in front of the photodetector 25. The condenser lens 24 condenses
the probe beam L3 on the light-receiving surface of the
photodetector 25. That is, the probe beam L3 forms a point-like
spot on the light-receiving surface of the photodetector 25. Thus,
it is possible to use a diode having a small light-receiving region
as the photodetector 25. Accordingly, it is not necessary to use a
camera in which light-receiving pixels are arranged in an array or
the like as the photodetector 25. Furthermore, it is out necessary
to perform image processing to images by the camera. Thus, it is
possible to simplify the configuration and the processing of the
apparatus.
[0081] (Measurement Result)
[0082] FIG. 6 shows a measurement result of the probe beam L3. FIG.
6 is a graph showing a measurement result in a condition-setting
substrate. The graph shows the measurement result of the probe beam
L3 when the irradiation intensity of the laser beam L1 to one
substrate 100 is changed. Specifically, the substrate 100 is
divided into 21 regions T80 to T100 as shown in FIG. 6, and the
irradiation intensity of the laser beam L1 is changed at each
region. The irradiation intensity is gradually increased from the
region T80 toward the region T100. Specifically, the numeral
representing each region means the irradiation intensity when the
irradiation intensity at the region T100 is set to 100. For
example, the region T80 means the 80% irradiation intensity of the
region T100, and the region T81 means the 81% irradiation intensity
of the region T100. Note that, the irradiation intensity at each
region is constant. The vertical axis indicates a detection value
of a detection signal of the photodetector 25. The detection value
in this graph corresponds to the voltage [V] of the detection
signal output from the photodetector 25.
[0083] FIG. 7 shows the average value and the standard deviation
.sigma. of the detection values V at each region. It is assumed
that the characteristic of the silicon film 101 is more excellent
as the detection values V are smaller. In this case, the region
having the smallest average value is the region T95, but the region
having the smallest standard deviation .sigma. is the region T85.
Thus, the irradiation intensity at the region T85 can be the
optimized irradiation intensity. In other words, the average value
is small but the variation of the detection value is large at the
region T95, and the standard deviation is large. For this reason,
ununiformity in the crystalline state is increased, and a defective
rate can be increased. By performing the annealing treatment using
the laser beam L1 having the irradiation intensity at the region
T85, it is possible to form the polysilicon film 101b having a
uniform crystalline state.
[0084] FIG. 8 is a diagram showing images of the substrate 100
captured by a camera and measurement results by the photodetector
25. FIG. 8 shows three substrate 100 as substrates I to III, and
the irradiation intensity of the laser beam L1 to each substrate is
changed. In addition, each of the substrates I to III is irradiated
with the laser beam L1 having the constant irradiation intensity.
The captured images are shown at the upper part of FIG. 8, and the
detection values (voltage values) are shown at the lower part. FIG.
8 shows that the detection values vary in the substrates I and III
the images of which have large uneven brightness. On the other
hand, the variation in the detection values is small in the
substrate II the image of which has small uneven brightness. In
this manner, by performing inspection based on the standard
deviation of the detection values, it is possible to improve the
accuracy of the quality determination.
[0085] (Method for Forming Polysilicon Film)
[0086] In the present embodiment, since the ELA apparatus 1 has a
function of quality determination, it is possible to further
increase the productivity. This point is described with reference
to FIGS. 9 and 10. FIG. 9 is a flowchart showing a method for
forming a polysilicon film using the ELA apparatus 1. More
specifically, FIG. 9 shows a forming method when a substrate is
determined to be defective by the inspection method according to
the present embodiment. FIG. 10 is a diagram showing an apparatus
layout for the ELA apparatus 1 and a cleaning apparatus 3 in a
manufacturing factory.
[0087] First, the ELA apparatus 1 performs the annealing treatment
and the quality determination (S101). Specifically, a transfer
robot 4 takes out the substrate 100 with an amorphous silicon film
cleaned by the cleaning apparatus 3 from a cassette 5. Then, the
transfer robot 4 carries the substrate 100 in the ELA apparatus 1.
Note that, the transfer robot 4 includes two hands and can hold the
substrate 100 to be carried in each apparatus and the substrate 100
to be carried out of each apparatus at the same time.
[0088] Then, the substrate 100 is irradiated with the laser beam L1
and the probe beam L2 while the substrate 100 is being conveyed as
shown in FIG. 1 and the like. For example, by driving a stage or
the like to convey the substrate 100, the annealing treatment and
the quality determination are performed. Since the substrate 100 is
irradiated simultaneously with the laser beam L1 and the probe beam
L2, the annealing treatment and the quality determination are
finished substantially at the same time. Since the photodetector 25
detects the probe beam L3 while the substrate 100 is being
conveyed, the processing apparatus 26 acquires a plurality of
detection values. Then, when the processing apparatus 26 determines
the substrate 100 to be defective based on the standard deviation
.sigma. of the detection values, the re-annealing treatment is
performed (S102). Here, steps S101 and S102 are performed in the
same ELA apparatus 1. That is, it is possible to perform steps S101
and S102 without carrying the substrate 100 out of the ELA
apparatus 1.
[0089] Next, a method for forming a polysilicon film using an ELA
apparatus according to a comparison example is described with
reference to FIGS. 11 and 12. FIG. 11 is a flowchart showing a
method for forming a polysilicon film using an ELA apparatus 201
according to a comparison example. FIG. 12 is a diagram showing a
layout for the ELA apparatus 201, a cleaning apparatus 203, and an
inspection apparatus 202 in a manufacturing factory. Note that, the
ELA apparatus 201 according the comparison example does not have a
function of quality determination. Thus, the inspection apparatus
202 is disposed in the vicinity of the ELA apparatus 201 and the
cleaning apparatus 203. The inspection apparatus 202 performs the
quality determination for the substrate 100.
[0090] First, the ELA apparatus 201 performs laser annealing
treatment (S201). Specifically, a transfer robot 204 takes out the
substrate 100 with an amorphous silicon film cleaned by the
cleaning apparatus 203 from a cassette 205. Then, the transfer
robot 204 carries the substrate 100 in the ELA apparatus 201. Then,
the ELA apparatus 201 performs annealing treatment.
[0091] When the annealing treatment is finished, the transfer robot
204 carries the substrate 100 subjected to the annealing treatment
out of the ELA apparatus (S202). When a mobile robot 204 that has
carried the substrate 100 out moves before the inspection apparatus
is carried in (S204), the transfer robot 204 carries the substrate
100 in the inspection apparatus 202 (S205).
[0092] The inspection apparatus 202 performs the quality
determination for the carried-in substrate 100 (S206). Here, an
example in which the substrate 100 is determined to be defective is
described. The transfer robot 204 carries the substrate 100 out of
the inspection apparatus 202 (S207). When the transfer robot 204
that has carried the substrate 100 out moves before the ELA
apparatus 201 is carried in (S209), the transfer robot 204 carries
the substrate 100 in the ELA apparatus 201 (S210). Then, the ELA
apparatus 201 performs re-annealing treatment to the substrate 100
determined to be defective (S211).
[0093] In this manner, since the ELA apparatus 201 according to the
comparison example does not have a function of quality
determination, the number of times of carrying-in and carrying-out
of the substrate 100 is increased. That is, the substrate 100 is
required to be carried in and carried out of the inspection
apparatus 202. This makes tact time longer, and it is difficult to
improve the productivity. In addition, a cleaning process by the
cleaning apparatus 203 can be required between the quality
determination process by the inspection apparatus 202 (S206) and
the re-annealing treatment S211 by the ELA apparatus 201. In this
case, the number of times of carrying-in and carrying-out of the
substrate 100 is further increased, and the productivity is
lowered.
[0094] In other words, it is possible for the ELA apparatus 1
according to the present embodiment to manufacture the substrate
100 with a polysilicon film with high productivity. That is, since
the number of times of carrying-in and carrying-out of the
substrate 100 is reduced, it is possible to finish the treatment in
a short time. Furthermore, since the annealing treatment and the
quality determination are performed in the same ELA apparatus 1, it
is not necessary to perform a cleaning process between the quality
determination and the re-annealing treatment. Accordingly, it is
possible to reduce the number of times of carrying-in and
carrying-out of the substrate 100 and to improve the productivity.
In addition, it is possible to evaluate the polysilicon film 101b
immediately after the irradiation with the laser beam L1. Thus, it
is possible to feed back the condition, such as transmittance, for
the next substrate 100 and to perform laser irradiation under an
appropriate condition.
Second Embodiment
[0095] An ELA apparatus 40 according to the present embodiment is
described with reference to FIGS. 13 and 14. FIG. 13 is a plan view
schematically showing a configuration of the ELA apparatus 40. FIG.
14 is a side view schematically showing the configuration of the
ELA apparatus 40. The configuration of the apparatus is
appropriately simplified in FIGS. 13 and 14. In the present
embodiment, a function of quality determination is added to the ELA
apparatus 40 provided with a gas-floating unit.
[0096] The ELA apparatus 40 includes a treatment room 41, a
continuous conveying path 42, gas-floating units 43a and 43b, a
suction part 44, and an opening 45. The treatment room 41 includes
a carrying-in port 41a and a carrying-out port 41b. The ELA
apparatus 40 includes, similarly to the first embodiment, an
annealing optical system 10, an illumination optical system 20, and
a detection optical system 30.
[0097] The ELA apparatus 40 according to the present embodiment is
provided with the gas-floating units 43a and 43b that float a
substrate 100 in the treatment room 41 in which annealing treatment
is performed. Note that, the basic configuration except for the
gas-floating units 43a and 43b is similar to the ELA apparatus 1
described in the first embodiment, and the description is
appropriately omitted. For example, the optical system of the ELA
apparatus 40 according to the present embodiment is substantially
similar to that of the ELA apparatus 1 according to the first
embodiment. However, a probe beam L3 enters a condenser lens 24
without passing through a mirror 12. In this case, a reflex mirror
that reflects almost all incident light can be used as the mirror
12 instead of a dichroic mirror.
[0098] The treatment room 41 of the ELA apparatus 40 has a
rectangular-parallelepiped wall part. The carrying-in port 41a (-X
side) and the carrying-out port 41b (+X side) are provided on the
walls facing in the longitudinal direction (the X direction) of the
treatment room 41. Each of the carrying-in port 41a and the
carrying-out port 41b may be opened or have an openable structure.
The openable structure can be a simple sealing structure. Note
that, the setting positions of the carrying-in port 41a and the
carrying-out port 41b are only required to be along the conveying
direction, and not limited to specific positions.
[0099] In the treatment room 41, the continuous conveying path 42
is provided from the carrying-in port 41a to the carrying-out port
41b. The gas-floating units 43a and 43b are disposed at the
continuous conveying path 42. The gas-floating unit 43a is disposed
at the carrying-in port 41a side, and the gas-floating unit 43b is
disposed at the carrying-out port 41b side. The opening 45 is
provided between the gas-floating unit 43a and the gas-floating
unit 43b. The opening 45 corresponds to an irradiation region P1 at
which laser annealing is performed.
[0100] The gas-floating units 43a and 43b are floating stages that
jet gas upward from below, and float and support the substrate 100
over themselves. Note that, the gas-floating units 43a and 43b each
have a plurality of jetting points (not shown) to adjust the
posture and bending of the substrate 100.
[0101] As shown in FIG. 14, the part at which the gas-floating unit
43a is provided in the continuous conveying path 42 is referred to
as a carrying-in conveying path 42a, and the part at which the
gas-floating unit 43b is provided is referred to as a carrying-out
conveying path 42b. In addition, the part corresponding to the
opening 45 in the continuous conveying path 42 is referred to as an
irradiation-region conveying path 42c.
[0102] The suction part 44 sucks the end portion of the substrate
100. The suction part 44 is moved along a guide rail (not shown) in
the X direction while the suction part 44 is sucking the substrate
100. It is thereby possible to covey the substrate 100 in the +X
direction.
[0103] The substrate 100 carried in from the carrying-in port 41a
is conveyed in the order of the carrying-in conveying path 42a, the
irradiation-region conveying path 42c, and the carrying-out
conveying path 42b. Then, when conveyed to the end of the
carrying-out conveying path 42b, the substrate 100 is carried out
of the carrying-out port 41b. Specifically, the substrate 100
carried in from the carrying-in port 41a is floated by the gas from
the gas-floating unit 43a. A floating substrate 1000 is conveyed in
the +X direction (for example, a substrate 100a in FIG. 14). Then,
when the substrate 100 reaches an illumination-region conveying
path 42c, the annealing treatment and detection of a probe beam are
performed (for example, a substrate 100b in FIG. 14).
[0104] At this time, the substrate 100 is irradiated with a laser
beam L1 and a probe beam L2 at the opening 45 in the
irradiation-region conveying path 42c. Thus, the illumination
optical system 20 is disposed so that the probe beam L2 passes
through the opening 45. For example, a lens 23 is disposed directly
under the opening 45. In this manner, the probe beam L2 passes
through the opening 45 disposed between the gas-floating unit 43a
and the gas-floating unit 43b. That is, an illumination region P2
of the probe beam L2 is positioned in the irradiation-region
conveying path 42c.
[0105] Then, the substrate 100 reaches the carrying-out conveying
path 42b, the substrate 100 is floated by the gas from both of the
gas-floating unit 43a and the gas-floating unit 43b. When the end
of the substrate 100 passes the carrying-in conveying path 42a, the
substrate 100 is floated by the gas from the gas-floating unit 43b
(for example, a substrate 100c in FIG. 14).
[0106] An inspection method according to the present embodiment is
suitable for the ELA apparatus 40 including a plurality of
gas-floating units of the gas-floating units 43a and 43b. For
example, the opening 45 is normally provided over the entire
substrate 100 in the Y direction (see FIG. 13). Thus, it is
possible for the ELA apparatus 40 according to the present
embodiment to form the illumination region P2 at an arbitrary
position in the Y direction. Accordingly, it is possible to form
the illumination region P2 at, for example, the center of the
substrate 100 in the Y direction. Thus, it is possible to evaluate
the crystalline state at the center of the substrate 100 in the Y
direction and to improve the accuracy of the quality
determination.
[0107] Note that, the illumination optical system 20 is disposed
under the substrate 100, and the detection optical system 30 is
disposed above the substrate 100 in the first and second
embodiments, but the positions of the illumination optical system
20 and the detection optical system 30 may be inverted. That is,
the illumination optical system 20 can be disposed above the
substrate 100, and the detection optical system 30 can be disposed
under the substrate 100. In this case, the lens 23 is disposed at
the +Z side of the substrate 100 as shown in FIG. 15. In second
embodiment, the probe beam transmitted through the substrate 100
passes through the opening 45. In addition, when the illumination
optical system 20 is disposed above the substrate 100 and the
detection optical system 30 is disposed under the substrate 100,
the probe beam L2 may be condensed with a lens different from the
projection lens 13.
[0108] (Organic EL Display)
[0109] A semiconductor device having the above polysilicon film is
suitable for a thin film transistor (TFT) array substrate used for
an organic electro luminescence (EL) display. That is, the
polysilicon film is used as a semiconductor layer having a source
region, a channel region, and a drain region of a TFT.
[0110] Hereinafter, a case in which a semiconductor device
according to the present embodiment is used for an organic EL
display is described. FIG. 16 is a cross section of a pixel circuit
of the organic EL display which is illustrated in a simplified
manner. The organic EL display device 300 shown in FIG. 16 is an
active-matrix-type display device in which a TFT is disposed in
each pixel PX.
[0111] The organic EL display device 300 includes a substrate 310,
a TFT layer 311, an organic layer 312, a color filter layer 313,
and a sealing substrate 314. FIG. 14 shows a top-emission-type
organic EL display device, in which the side of the sealing
substrate 314 is located on the viewing side. Note that the
following description is given to show an example of a
configuration of an organic EL display device and this embodiment
is not limited to the below-described configuration. For example, a
semiconductor device according to this embodiment may be used for a
bottom-emission-type organic EL display device.
[0112] The substrate 310 is a glass substrate or a metal substrate.
The TFT layer 311 is provided on the substrate 310. The TFT layer
311 includes TFTs 311a disposed in the respective pixels PX.
Further, the TFT layer 311 includes wiring lines (not shown)
connected to the TFTs 311a, and the like. The TFTs 311a, the wiring
lines, and the like constitute pixel circuits.
[0113] The organic layer 312 is provided on the TFT layer 311. The
organic layer 312 includes an organic EL light-emitting element
312a disposed in each pixel PX. The organic EL light-emitting
element 312a has, for example, a laminated structure in which an
anode, a hole injection layer, a hole transport layer, a
light-emitting layer, an electron transport layer, an electron
injection layer, and a cathode are laminated. In the case of the
top emission type, the anode is a metal electrode and the cathode
is a transparent conductive film made of ITO (Indium Tin Oxide) or
the like. Further, in the organic layer 312, separation walls 312b
for separating organic EL light-emitting elements 312a are provided
between pixels PX.
[0114] The color filter layer 313 is provided on the organic layer
312. The color filter layer 313 includes color filters 313a for
performing color displaying. That is, in each pixel PX, a resin
layer colored in R (red), G (green), or B (blue) is provided as the
color filter 313a. When white light emitted from the organic layer
312 passes through the color filters 313a, the white light is
converted into light having RGB colors. Note that in the case of a
three-color system in which organic EL light-emitting elements
capable of emitting each color of RGB are provided in the organic
layer 312, the color filter layer 313 may be unnecessary.
[0115] The sealing substrate 314 is provided on the color filter
layer 313. The sealing substrate 314 is a transparent substrate
such as a glass substrate and is provided to prevent deterioration
of the organic EL light-emitting elements of the organic layer
312.
[0116] Electric currents flowing through the organic EL
light-emitting elements 312a of the organic layer 312 are changed
by display signals supplied to the pixel circuits. Therefore, it is
possible to control an amount of light emitted in each pixel PX by
supplying a display signal corresponding to a display image to each
pixel PX. As a result, it is possible to display a desired
image.
[0117] In an active matrix display device such as an organic EL
display, one pixel PX is provided with one or more TFTs (for
example, a switching TFT and a driving TFT). Then, the TFT of each
pixel PX is provided with a semiconductor layer having a source
region, a channel region, and a drain region. The polysilicon film
according to the present embodiment is suitable for a semiconductor
layer of a TFT. That is, by using the polysilicon film manufactured
by the above manufacturing method for a semiconductor layer of a
TFT array substrate, it is possible to suppress in-plane
ununiformity which is the TFT characteristics. Thus, it is possible
to manufacture a display device having an excellent display
characteristic with high productivity.
[0118] (Manufacturing Method of Semiconductor Device)
[0119] A manufacturing method of a semiconductor device using the
ELA apparatus according to the present embodiment is suitable for
manufacturing a TFT array substrate. The manufacturing method of a
semiconductor device having a TFT is described with reference to
FIGS. 17 to 24. FIGS. 17 to 24 are cross-sectional views showing
processes for manufacturing a semiconductor device. In the
following description, a manufacturing method of a semiconductor
device having an inverted staggered TFT is described.
[0120] First, as shown in FIG. 17, a gate electrode 402 is formed
on a glass substrate 401. Note that, the glass substrate 401
corresponds to the above substrate 100. As the gate electrode 402,
for example, a metal thin film containing aluminium can be used. A
metal thin film is formed on the glass substrate 401 by a
sputtering method or a deposition method. Then, the metal thin film
is patterned by photolithography to form the gate electrode 402. In
a photolithography method, processing, such as resist coating,
exposure, developing, etching, and resist stripping, is performed.
Note that, various types of wiring may be formed in the same
process as the patterning of the gate electrode 402.
[0121] Next, a gate insulating film 403 is formed on the gate
electrode 402 as shown in FIG. 18. The gate insulating film 403 is
formed so as to cover the gate electrode 402. Then, an amorphous
silicon film 404 is formed on the gate insulating film 403 as shown
in FIG. 19. The amorphous silicon film 404 is arranged so as to
overlap the gate electrode 402 interposing the gate insulating film
403.
[0122] The gate insulating film 403 is a silicon nitride film
(SiN.sub.x) or a silicon oxide film (SiO.sub.2 film), or a
lamination film thereof, or the like. Specifically, the gate
insulating film 403 and the amorphous silicon film 404 are
continuously formed by a chemical vapor deposition (CVD)
method.
[0123] Then, the amorphous silicon film 404 is irradiated with the
laser beam L1 to form a polysilicon film 405 as shown in FIG. 20.
That is, the amorphous silicon film 404 is crystallized by the ELA
apparatus 1 shown in FIG. 1 and the like. The polysilicon film 405
with silicon crystallized is thereby formed on the gate insulating
film 403. The polysilicon film 405 corresponds to the above
polysilicon film 101b.
[0124] At this time, the polysilicon film 405 is inspected by the
inspection method according to the present embodiment. When the
polysilicon film 405 does not meet a predetermined criterion, the
polysilicon film 405 is irradiated with a laser beam again. Thus,
it is possible to further uniformize the characteristic of the
polysilicon film 405. Since the in-plane ununiformity can be
suppressed, it is possible to manufacture a display device having
an excellent display characteristic with high productivity.
[0125] Note that, although not shown, the polysilicon film 405 is
pattered by a photolithography method. In addition, impurities may
be introduced into the polysilicon film 405 by an ion implantation
method or the like.
[0126] Then, an interlayer insulating film 406 is formed on the
polysilicon film 405 as shown in FIG. 21. The interlayer insulating
film 406 is provided with contact holes 406a for exposing the
polysilicon film 405.
[0127] The interlayer insulating film 406 is a silicon nitride film
(SiN.sub.x) or a silicon oxide film (SiO.sub.2 film), or a
lamination film thereof, or the like. Specifically, the interlayer
insulating film 406 is formed by a chemical vapor deposition (CVD)
method. Then, the interlayer insulating film 406 is patterned by a
photolithography method to form the contact holes 406a.
[0128] Next, a source electrode 407a and a drain electrode 407b are
formed on the interlayer insulating film 406 as shown in FIG. 22.
The source electrode 407a and the drain electrode 407b are formed
so as to cover the contact holes 406a. That is, the source
electrode 407a and the drain electrode 407b are formed from the
inside of the contact holes 406a over the interlayer insulating
film 406. Thus, the source electrode 407a and the drain electrode
407b are electrically connected to the polysilicon film 405 though
the contact holes 406a.
[0129] Accordingly, a TFT 410 is formed. The TFT 410 corresponds to
the above TFT 311a. The region overlapping the gate electrode 402
in the polysilicon film 405 is a channel region 405c. The source
electrode 407a side of the polysilicon film 405 from the channel
region 405c is a source region 405a, and the drain electrode 407b
side is a drain region 405b.
[0130] The source electrode 407a and the drain electrode 407b are
formed of a metal thin film containing aluminium. A metal thin film
is formed on the interlayer insulating film 406 by a sputtering
method or a deposition method. Then, the metal thin film is
patterned by photolithography to form the source electrode 407a and
the drain electrode 407b. Note that, various types of wiring may be
formed in the same process as the patterning of the source
electrode 407a and the drain electrode 407b.
[0131] Then, a planarization film 408 is formed on the source
electrode 407a and the drain electrode 407b as shown in FIG. 23.
The planarization film 408 is formed so as to cover the source
electrode 407a and the drain electrode 407b. The planarization film
408 is provided with a contact hole 408a for exposing the drain
electrode 407b.
[0132] The planarization film 408 is formed of, for example, a
photosensitive resin film. A photosensitive resin film is coated on
the source electrode 407a and the drain electrode 407b, and exposed
and developed. Accordingly, it is possible to pattern the
planarization film 408 having the contact hole 408a.
[0133] Then, a pixel electrode 409 is formed on the planarization
film 408 as shown in FIG. 24. The pixel electrode 409 is formed so
as to cover the contact hole 408a. That is, the pixel electrode 409
is formed from the inside of the contact hole 408a over the
planarization film 408. Thus, the pixel electrode 409 is
electrically connected to the drain electrode 407b through the
contact hole 408a.
[0134] The pixel electrode 409 is formed of a transparent
conductive film or a metal thin film containing aluminium. A
conductive film (a transparent conductive film or a metal thin
film) is formed on the planarization film 408 by a sputtering
method. Then, the conductive film is patterned by the
photolithography method. The pixel electrode 409 is thereby formed
on the planarization film 408. In the case of a driving TFT of an
organic EL display, the organic EL light emitting device 312a, the
color filter (CF) 313a, and the like as shown FIG. 16 are formed on
the pixel electrode 409. Note that, in the case of a top-emission
type organic EL display, the pixel electrode 409 is formed of a
metal thin film containing aluminium or silver which have a high
reflectance. In the case of a bottom-emission type organic EL
display, the pixel electrode 409 is formed of a transparent
conductive film such as ITO.
[0135] The processes for manufacturing an inverted staggered TFT
has been described. The manufacturing method according to the
present embodiment may be applied to manufacture of an inverted
staggered TFT. It is obvious that the manufacturing method of a TFT
is not limited to a TFT for an organic EL display and can be
applied to manufacture of a TFT for a liquid crystal display
(LCD).
[0136] In addition, it has been described that the laser annealing
apparatus according to the present embodiment irradiates an
amorphous silicon film with a laser beam to form a polysilicon film
in the above description, but the laser annealing apparatus may
irradiate an amorphous silicon film with a laser beam to form a
micro-crystal silicon film. Furthermore, a laser beam for
performing annealing is not limited to excimer laser. In addition,
the method according to the present embodiment can be applied to a
laser annealing apparatus that crystallizes thin films other than a
silicon film. That is, as long as the laser annealing apparatus
irradiates an amorphous film with a laser beam to form a
crystallized film, the method according to the present embodiment
can be applied. It is possible for the laser annealing apparatus
according to the present embodiment to properly evaluate a
substrate with a crystallized film.
[0137] In the above description, it has been described that the
manufacturing method according to the present embodiment is applied
to manufacture of a TFT array substrate for a display device, such
as an organic EL display or a crystal display. However, the method
can be applied to manufacture of a TFT array substrate for other
display devices. Furthermore, the manufacturing method according to
the present embodiment can be used for other TFT array substrates
except for a display device. For example, the semiconductor device
according to the present embodiment may be used for a TFT array
substrate for a flat panel detector such as an X-ray image sensor.
It is possible to manufacture a TFT array substrate having a
uniform semiconductor layer characteristic with high
productivity.
[0138] (Determination Method of Optimized Energy Density)
[0139] With reference to FIGS. 25 and 26, a method for determining
an optimized energy density (OED) of the laser beam L1 with which a
substrate is to be irradiated is described. FIG. 25 is a flowchart
showing a method for determining the OED. FIG. 26 is a schematic
diagram for explaining regions of a substrate in the method for
determining the OED.
[0140] Here, the substrate 100 is divided into a plurality of
regions in the X direction. As shown in FIG. 26, the divided
regions are referred to as a region Xn-1, a region Xn, a region
Xn+1, a region Xn+2, and the like. Note that, the substrate 100 is
irradiated with the laser beam L1 and the probe beam L2 in the
order of the region Xn-1, the region Xn, the region Xn+1, and the
region Xn+2. Thus, after the transmittance at the region Xn-1 is
measured, the transmittance at the region Xn is measured.
[0141] At the region Xn-1, the region Xn, the region Xn+1, and the
region Xn+2, the measured transmittances are respectively referred
to as a transmittance Tn-1, a transmittance Tn, a transmittance
Tn+1, and a transmittance Tn+2. At each region, a plurality of
detection values of the transmittance is acquired. For example, the
transmittance Tn contains a plurality of detection values. Then,
the standard deviation of the detection values of the transmittance
Tn-1 is referred to as a standard deviation .sigma.n-1. The
standard deviations of the detection values of the transmittance
Tn, the transmittance Tn+1, and the transmittance Tn+2 are
respectively referred to as a standard deviation an, a standard
deviation .sigma.n+1, and a standard deviation .alpha.n+2.
[0142] First, the processing apparatus 26 calculates the standard
deviation .sigma.n-1 at the region Xn-1 (S21). Then, the processing
apparatus 26 compares the standard deviation .sigma.n-1 with a
threshold .sigma.th of the standard deviation (S22). When the
standard deviation .sigma.n-1 is greater than the threshold
.sigma.th, the irradiation intensity of the laser beam L1 (energy
density) is changed (S23). That is, a laser beam source 11
increases or lowers the output. When the standard deviation
.sigma.n-1 is equal to or less than the threshold .sigma.th, the
irradiation intensity of the laser beam L1 is maintained (S24).
[0143] Next, the processing apparatus 26 calculates the standard
deviation .sigma.n at the region Xn (S25). Then, the processing
apparatus 26 compares the standard deviation .sigma.n with the
threshold .sigma.th of the standard deviation (S26). When the
standard deviation .sigma.n is greater than the threshold
.sigma.th, the irradiation intensity of the laser beam L1 is
changed (S27). That is, the laser beam source 11 increases or
lowers the output. The output of a probe beam source 21 is
determined to be increased or lowered in S27 based on the
comparison result of the standard deviation .sigma.n with the
standard deviation .sigma.n-1t. Then, the calculation n=n+1 is
performed, that is, n is incremented, and the processing from S21
is consecutively performed. When the standard deviation .sigma.n is
equal to or less than the threshold .sigma.th, the irradiation
intensity of the laser beam L1 is maintained (S28).
[0144] It is thereby possible to determine the OED of the laser
beam L1. In addition, while the substrate 100 is being irradiated
with the laser beam L1, the photodetector 25 detects the probe beam
L3. Thus, it is possible to optimize the energy density of the
laser beam L1 in real time. That is, when the standard deviation of
the transmittance is greater than the threshold .sigma.th, the
laser beam source 11 changes the irradiation intensity of the laser
beam L1. Accordingly, it is possible to reduce the standard
deviation of the transmittance at the next region. Thus, it is
possible to form a high-quality polysilicon film.
Third Embodiment
[0145] An ELA apparatus 500 according to a third embodiment is
described with reference to FIGS. 27 and 28. FIG. 27 is a side view
schematically showing a configuration of the ELA apparatus 500, and
FIG. 28 is a plan view. As shown in FIG. 27, the ELA apparatus 500
includes a mirror 512, a projection lens 513, a probe beam source
521, a lens 523, a condenser lens 524, a photodetector 525, a door
valve 543, a chamber 550, a surface plate 556, a drive mechanism
557, a suction stage 558, and a pusher pin 559.
[0146] In the present embodiment, the arrangement of the optical
system for a probe beam, specifically, the arrangement of the probe
beam source 521 and the photodetector 525 is different from that in
the first and second embodiments. When a conveying robot 504
carries a substrate 100 out of the ELA apparatus 500, an inspection
with a probe beam is performed. That is, after annealing treatment
with a laser beam L1 is finished, an inspection with a probe beam
L2 is performed. In addition, the suction stage 558 instead of the
gas-floating unit 43 described in the second embodiment holds the
substrate 100 in the present embodiment. The configuration and
processing except for these points are similar to the ELA apparatus
500 in the first and second embodiments, and the description is
omitted. For example, the optical system for irradiating the
substrate 100 with the laser beam L1 is similar to that in the
first embodiment. In addition, the inspection method with a probe
beam is also similar to that in the first and second embodiments,
and the description is omitted.
[0147] The ELA apparatus 500 includes a treatment chamber 550
surrounding a treatment room 541. The inside of the treatment
chamber 550 is the treatment room 541. The treatment room 541 is in
inert gas atmosphere, for example, nitrogen gas or the like. A
carrying-out port 541b is provided at a side wall 551 of the
treatment chamber 550. The carrying-out port 541b is provided at
the end portion of the treatment chamber 550 at the +X side. Then,
the conveying robot 504 is disposed outside the treatment chamber
550. The conveying robot 504 includes a robot hand 505 capable of
entering the treatment room 541 through the carrying-out port
541b.
[0148] The conveying robot 504 carries the substrate 100 at a
carrying-out position out through the carrying-out port 541b. That
is, the robot hand 505 enters the treatment room 541 from the
carrying-out port 541b and takes out the substrate 100 subjected to
the treatment from the treatment room 541. As shown in FIG. 28, the
robot hand 505 moves the substrate 100 in the +X direction, and the
substrate 100 is carried out of the treatment room 541 through the
carrying-out port 541b. The conveying robot 504 carries the
carried-out substrate 100 in a cassette.
[0149] Note that, the carrying-out port 541b may be used as a
carrying-in port. That is, the conveying robot 504 may carry the
substrate 100 before the treatment through the carrying-out port
541b. Alternatively, a carrying-in port separately from the
carrying-out port 541b may be provided to the treatment chamber
550. The carrying-out port 541b is provided with the door valve
543. The door valve 543 is opened at the time of carrying the
substrate 100 out or the like, and the door valve 543 is closed at
the time of the irradiation with the laser beam L1.
[0150] The surface plate 556, the drive mechanism 557, and the
suction stage 558 are provided in the treatment room 541. The
surface plate 556 is fixed in the treatment chamber 550. The
suction stage 558 is attached to the surface plate 556 through the
drive mechanism 557. As shown in FIG. 28, the drive mechanism 557
includes an X shaft 557X that moves the suction stage 558 in the X
direction and a shaft 557Y that moves the suction stage 558 in the
Y direction. As described in the first embodiment, the laser beam
L1 is a line beam having its longitudinal direction in the Y
direction on the substrate 100. The drive mechanism 557 moves the
suction stage 558 in the X direction. Accordingly, while the
suction stage 558 is moving the substrate 100 along a conveying
path, the substrate 100 is irradiated with the laser beam L1. In
addition, the drive mechanism 557 may have a 0 shaft that rotates
the suction stage 558 about the Z axis.
[0151] The suction stage 558 sucks and holds the substrate 100. The
suction stage 558 is provided with the pusher pin 559 for carrying
the substrate 100 in and out. The pusher pin 559 is provided so as
to be raised and lowered. When the substrate 100 is carried in or
out, the pusher pin 559 is raised to transfer the substrate 100 to
the robot hand 505.
[0152] Specifically, when the pusher pin 559 is raised while the
substrate 100 is on the suction stage 558, a gap is generated
between the substrate 100 and the suction stage 558. Then, the
robot hand 505 enter the gap between the substrate 100 and the
suction stage 558. When the pusher pin 559 is lowered while the
robot hand 505 is being under the substrate 100, the robot hand 505
holds the substrate 100.
[0153] Alternatively, the robot hand 505 conveys the substrate 100
onto the suction stage 558 while the pusher pin 559 is being
lowered. Then, when the pusher pin 559 is raised, the pusher pin
559 holds the substrate 100. When the pusher pin 559 is lowered
while the substrate 100 is being placed on the pusher pin 559, the
substrate 100 is placed onto the suction stage 558. Accordingly,
the suction stage 558 becomes ready to suck the substrate 100. The
suction stage 558 sucks the substrate 100 at the time of the
irradiation with the laser beam L1. When the irradiation with the
laser beam L1 is finished, the suction stage 558 releases the
suction.
[0154] The probe beam source 521, the lens 523, the condenser lens
524, and the photodetector 525 are further provided in the
treatment room 541. The probe beam source 521, the lens 523, the
condenser lens 524, and the photodetector 525 are disposed in the
vicinity of the side wall 551. For example, the probe beam source
521, the lens 523, the condenser lens 524, and the photodetector
525 are fixed on the surface at the treatment room 541 side of the
side wall 551. For example, while the suction stage 558 is being
stopped at the substrate carrying-out position (the endmost of the
+X side), the probe beam source 521 emits the probe beam L2.
[0155] The probe beam L2 emitted from a probe beam source L2 is
condensed by the lens 523 and enters the substrate 100. During the
robot hand 505 conveys the substrate 100, a polysilicon film 101b
is irradiated with the probe beam L2 outside the suction stage 558.
A probe beam L3 transmitted through the substrate 100 is condensed
by the condenser lens 524 on the photodetector 525. The
photodetector 525 outputs detection signals to a processing
apparatus (the illustration is omitted) as described above.
[0156] When the robot hand 505 carries the substrate 100 out
through the carrying-out port 541b to the outside of the treatment
room 541, an inspection with the probe beam L2 can be performed.
The robot hand 505 carries the substrate 100 on the suction stage
558 out, and the irradiation position of the probe beam L2 is
changed toward the +X direction. During the robot hand 505 carries
the substrate 100 out, the substrate 100 passes between the lens
523 and the condenser lens 524. The probe beam L2 from the probe
beam source 521 is condensed by the lens 523 on the substrate 100.
The probe beam L2 forms an illumination region P2 outside the
suction stage 558 (see FIG. 28). Note that, the illumination region
P2 of the probe beam L2 has a linear shape extending in the Y
direction, but may have a point-like shape.
[0157] The probe beam L3 having passed through the polysilicon film
101b of the substrate 100 is condensed by the condenser lens 524 on
the photodetector 525. During the robot hand 505 carries the
substrate 100 out, the photodetector 525 detects the probe beam L3.
That is, the robot hand 505 moves the substrate 100 in the +X
direction in order for the robot hand 505 to carry the substrate
100 out through the carrying-out port 541b. While the substrate 100
is being moved in the +X direction, the photodetector 525 detects
the probe beam L3. It is thereby possible to measure the
transmittance of the polysilicon film 101b of the substrate 100 in
an inspection line IL as shown in FIG. 28. Note that, since the
robot hand 505 moves the substrate 100 in the +X direction, the
inspection line IL has a belt-like shape or a line shape having its
longitudinal direction in the X direction.
[0158] The annealing laser beam L1 forms a linear irradiation
region P1 having its longitudinal direction in the Y direction (see
FIG. 3). On the other hand, the robot hand 505 moves the substrate
100 in the X direction. Thus, at the time of the inspection with a
probe beam, the substrate 100 is scanned along the latitudinal
direction of the irradiation region P1. It is thereby possible to
properly evaluate shot unevenness.
[0159] Unlike the gas-floating unit, it can be difficult for the
suction stage 558 to be provided with the optical path of a probe
beam. Although this suction stage 558 is used, it is possible for
the photodetector 525 to detect the probe beam L3 transmitted
through the substrate 100 with the configuration in the present
embodiment. Thus, it is possible to properly inspect the substrate
100. When the substrate 100 is determined to be abnormal based on
the standard deviation or the average value of the detection
values, the substrate 100 is carried in the ELA apparatus 500 and
re-irradiated with the laser beam L1. For example, the portion
having shot unevenness or the entire substrate 100 may be
re-irradiated with the laser beam L1. Accordingly, it is possible
to improve the yield.
[0160] The lens 523 forms the illumination region P2 of the probe
beam L2 at the X position between the carrying-out port 541b and
the suction stage 558. In the substrate conveying process by the
robot hand 505, the substrate 100 is moved for a longer distance
than the substrate 100. In the X direction in which the substrate
100 is conveyed, the inspection line IL is formed over the entire
substrate 100. By evaluating the transmittance in the inspection
line IL, it is possible to evaluate the crystalline state of the
polysilicon film 101b. In addition, since the inspection can be
performed in the substrate conveying process, it is unnecessary to
convey the substrate 100 only for performing the inspection.
Accordingly, it is possible to prevent the increase in tact time.
Furthermore, the probe beam source 521, the lens 523, the condenser
lens 524, and the photodetector 525 are attached in the vicinity of
the side wall 551. Thus, it is possible to prevent a space for
providing an optical system from increasing.
[0161] In addition, two illumination regions P2 of the probe beam
L2 are formed on the substrate 100 as shown in FIG. 28 in the
present embodiment. That is, the substrate 100 is irradiated
simultaneously with the two probe beams L2 separated in the Y
direction. Accordingly, it is possible to simultaneously measure
the transmittances of the two portions of the substrate 100. It is
thereby possible to more reliably perform evaluation.
[0162] For example, when particles are attached to a substrate,
abnormal values indicating that the transmittance is greatly
lowered can be detected at the points of particles. When such
abnormal values are detected, the standard deviation of the
detection values is greatly affected. However, it is difficult to
determine whether the abnormal values are caused by particles or by
the crystalline state. Thus, by irradiating the substrate with the
two or more separated probe beams L2 as described in the present
embodiment, it is possible to eliminate the influence of the
abnormal values caused by particles. That is, when one abnormal
value at the same X position is detected, the abnormal value is
determined to be caused by particles, or when abnormal values are
detected at two portions, the abnormal values are determined to be
caused by shot unevenness. Thus, by eliminating abnormal values
caused by particles to calculate the standard deviation, it is
possible to more reliably perform evaluation.
[0163] Note that, it has been described that the robot hand 505
conveys the substrate 100 along the latitudinal direction of the
irradiation region P1 of the laser beam L1 in the above
description, but the latitudinal direction of the irradiation
region P1 of the laser beam L1 may not be the same as the conveying
direction of the robot hand 505. For example, before the
irradiation with the laser beam L1, the suction stage 558 can
rotate the substrate 100 about the Z axis (in the .theta.
direction) by 90.degree.. Alternatively, the robot hand 505 can
move the substrate 100 in the Y direction according to the position
of a carrying-out port 541. In such cases, the latitudinal
direction of the irradiation region P1 of the laser beam L1 is
orthogonal to the conveying direction of the robot hand 505. That
is, the inspection line IL is parallel to the longitudinal
direction of the irradiation region P1 of the laser beam L1.
[0164] In this case, scanning unevenness instead of shot unevenness
of the laser beam L1 can be evaluated. Note that, scanning
unevenness is not caused by laser but by an optical system and also
referred to as optics unevenness. Specifically, if particles or the
like are attached to the optical element included in the optical
system of the laser beam L1, a shadow appears on a part of the
irradiation region P1. Since the detection light amount is lowered
at the position where the shadow appears, an abnormal value is
detected. The shadow appears at the same position in the
irradiation region P1, abnormal values are detected along the line
parallel to the latitudinal direction of the irradiation region P1.
Thus, abnormal values occur in the line at the same position
regardless of the substrate 100, which indicates that there is
scanning unevenness. Note that, in order to both evaluate scanning
unevenness and shot unevenness, it is only required to evaluate a
substrate irradiated with a laser at the suction stage set to
0.degree. and the substrate irradiated with a laser at the suction
stage rotated by 90.degree..
[0165] Note that, when the robot hand 505 carries the substrate 100
out, the substrate 100 can be bent and moved up and down. When the
substrate 100 is moved up and down, the size of the illumination
region P2 on the substrate 100 is changed. That is, the
illumination region P2 has the smallest size when the focal point
of the probe beam L2 by the lens 523 is on the substrate 100, but
the size of the illumination region P2 becomes larger as the
substrate 100 is separated farther from the focal point.
[0166] FIG. 29 shows the size of the probe beam L2 at the Z
position when the focal point at the Z position is set as 0. FIG.
29 shows a simulation result when the probe beam L2 having the
wavelength of 405 nm and the size of 4 mm is condensed by the lens
523 of f300 mm. The horizontal axis indicates a Z position, and the
vertical axis indicates the size of the probe beam L2. In FIG. 29,
the size of the probe beam L2 is about 38 .mu.m at the focal point.
When the Z position is shifted by .+-.2 mm, the size of the probe
beam L2 is 47 .mu.m, and this does not matter practically. That is,
if the probe beam L2 having the size of 47 .mu.m passes though the
substrate 100, the photodetector 525 detects the probe beam L3
transmitted through the substrate 100 by the condenser lens
524.
[0167] (Optical System for Probe Beam)
[0168] Next, a configuration of an optical system for a probe beam
in an ELA apparatus according to a third embodiment is described.
FIGS. 30 to 32 are diagrams showing configurations of optical
systems for the probe beam L2. FIGS. 30 to 32 each show an optical
system that irradiates the substrate 100 with the probe beam L2 and
detects the probe beam L3 transmitted through the substrate
100.
[0169] <Optical System 501>
[0170] FIG. 30 is a schematic diagram showing an example of an
optical system (referred to as an optical system 501). The optical
system 501 includes a probe beam source 521, a one-side expander
526, a lens 523, a mirror 522, a mirror 529, a collimation lens
528, a condenser lens 524, and a photodetector 525.
[0171] The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526 has
two lenses and expands the beam diameter in the Y direction. Note
that, the conveying direction of the substrate 100 by the robot
hand 505 is the X direction. The substrate 100 is irradiated with
the probe beam L2 from the one-side expander 526 through the lens
523 and the mirror 522. Note that, the lens 523 is a cylindrical
lens and condenses the probe beam L2 in the X direction. Thus, the
probe beam L2 forms, on the substrate 100, a linear illumination
region having its longitudinal direction in the Y direction and its
latitudinal direction in the X direction.
[0172] The probe beam L3 transmitted through the substrate 100 is
reflected by the mirror 529 and enters the collimation lens 528.
The collimation lens 528 turns the probe beam L3 into a parallel
luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to
prevent stray light having a wavelength other than the wavelength
of the probe beam from entering the photodetector 525.
[0173] With the optical system 501, it is possible to properly
evaluate the crystalline state. In addition, the optical system 501
may be provided with a camera 530 that confirms the focal point of
the lens 523. A camera 30 captures an image of the illumination
region of the probe beam L2 and its surroundings. The focal point
can be adjusted based on the image by the camera 530. The camera
530 may be provided only at the time of installing the optical
system 501.
[0174] <Optical System 502>
[0175] FIG. 31 is a schematic diagram showing another example of an
optical system for a probe beam (referred to as an optical system
502). The optical system 502 has a configuration for detecting a
probe beam having passed through the substrate 100 twice. The
optical system 502 includes a probe beam source 521, a one-side
expander 526, a lens 523, a mirror 522, a mirror 531, a collimation
lens 532, a condenser lens 533, a mirror 534, a mirror 529, a
collimation lens 528, a condenser lens 524, and a photodetector
525.
[0176] The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526 has
two lenses and expands the beam diameter in the Y direction. The
substrate 100 is irradiated with the probe beam L2 from the
one-side expander 526 through the lens 523 and the mirror 522. Note
that, the lens 523 is a cylindrical lens and condenses the probe
beam L2 in the X direction. Thus, the probe beam L2 reflected by
the mirror 522 forms, on the substrate 100, a linear illumination
region having its longitudinal direction in the Y direction and its
latitudinal direction in the X direction.
[0177] The probe beam L2 transmitted through the substrate 100 is
reflected by the mirror 531 and enters the collimation lens 532.
The collimation lens 532 turns the probe beam L2 into a parallel
luminous flux. The probe beam L2 from the collimation lens 532
enters the substrate 100 through the condenser lens 533 and the
mirror 534. Note that, the condenser lens 533 is a cylindrical lens
and condenses the probe beam L2 in the X direction. Thus, the probe
beam L2 reflected by the mirror 534 forms, on the substrate 100, a
linear illumination region having its longitudinal direction in the
Y direction and its latitudinal direction in the X direction.
[0178] The probe beam L3 transmitted through the substrate 100 is
reflected by the mirror 529 and enters the collimation lens 528.
The collimation lens 528 turns the probe beam L3 into a parallel
luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to stray
light having a wavelength other than the wavelength of the probe
beam from entering the photodetector 525.
[0179] In this manner, the photodetector 525 detects the probe beam
L3 having passed through the polysilicon film 101b twice in the
optical system 502. Accordingly, it is possible to emphasize
transmittance unevenness. Thus, it is possible to properly evaluate
the crystalline state.
[0180] The focal point by the lens 523 is shifted from the focal
point by the condenser lens 533 in the Y direction on the substrate
100. That is, when the conveying direction by the robot hand 505 is
the X direction, the probe beam L2 has passed through the substrate
100 twice at different Y positions and at the same X position.
Accordingly, since shot unevenness is emphasized, it is possible to
properly evaluate the crystalline state. Naturally, the optical
system 502 may be configured so that a probe beam passes through
the polysilicon film 101b three times or more. For example, a
mirror and a lens can be added in order for a probe beam to pass
through the polysilicon film 101b three times or more.
[0181] The first and second positions where the probe beam L2
passes through the substrate 100 are separated in the Y direction.
Thus, it is possible to reduce the influence of particles. For
example, if a particle is attached to the first passing position,
the particle is not attached to the second passing position. Thus,
it is possible to reduce the influence of particles on lowering the
transmittance. Accordingly, it is possible to properly evaluate the
crystalline state.
[0182] The optical system 502 may be provided with cameras 530a and
530b that respectively confirm the focal points of the lens 523 and
the condenser lens 533. The cameras 530a and 530b each capture an
image of the illumination region of the probe beam L2 and its
surroundings. The focal points can be adjusted based on the images
by the cameras 530a and 530b. The cameras 530a and 530b may be
provided only at the time of installing the optical system 502.
[0183] <Optical System 503>
[0184] FIG. 32 is a schematic diagram showing another example of an
optical system for a probe beam (referred to as an optical system
503). The optical system 503 has a configuration for detecting a
probe beam having passed through the substrate 100 twice. In
addition, the probe beam L2 passes through the substrate 100 at the
same position twice in an optical system 303. The optical system
503 includes a probe beam source 521, a one-side expander 526, a
polarizing plate 536, a lens 523, a beam splitter 537, a condenser
lens 533, a quarter-wavelength plate 538, a mirror 539, a
collimation lens 528, a condenser lens 524, and a photodetector
525.
[0185] The probe beam source 521 generates a probe beam L2 having a
wavelength of 405 nm. The probe beam L2 from the probe beam source
521 enters the one-side expander 526. The one-side expander 526
expands the beam diameter in the Y direction. The substrate 100 is
irradiated with the probe beam L2 from the one-side expander 526
through the polarizing plate 536, the lens 523, and the beam
splitter 537. The polarizing plate 536 turns the probe beam L2 into
linearly polarized light along a first direction. The beam splitter
537 is, for example, a polarizing beam splitter, reflects the
linearly polarized light along the first direction, and transmits
linearly polarized light along a second direction orthogonal to the
first direction. Thus, the beam splitter 537 reflects the probe
beam L2 toward the substrate 100.
[0186] The lens 523 is a cylindrical lens and condenses the probe
beam L2 in the X direction. Accordingly, the probe beam L2 forms,
on the substrate 100, a linear illumination region having its
longitudinal direction in the Y direction and its latitudinal
direction in the X direction.
[0187] The probe beam L2 transmitted through the substrate 100
enters the condenser lens 533 which is a cylindrical lens. The
condenser lens 533 functions as a collimation lens that turns the
probe beam L2 from the substrate 100 into a parallel luminous flux.
The probe beam L2 from the condenser lens 533 is reflected by the
mirror 539 through the quarter-wavelength plate 538. The mirror 539
is a total reflection mirror and makes the probe beam L2
transmitted through the quarter-wavelength plate 538 enter the
quarter-wavelength plate 538 again. Since the probe beam L2 passed
through the quarter-wavelength plate 538 twice, the linearly
polarized light is rotated by 90.degree.. Thus, the probe beam L2
directed from the quarter-wavelength plate 538 toward the substrate
100 is linearly polarized light along the second direction.
[0188] The probe beam L2 having passed through the
quarter-wavelength plate 538 twice is condensed by the condenser
lens 533 on the substrate 100. As described above, the probe beam
L2 forms, on the substrate 100, a linear illumination region having
its longitudinal direction in the Y direction and its latitudinal
direction in the X direction. The probe beam L3 transmitted through
the substrate 100 enters the beam splitter 537. As described above,
the probe beam L3 is linearly polarized light along the second
direction and transmitted through the beam splitter 537. The probe
beam L3 transmitted through the beam splitter 537 enters the
collimation lens 528.
[0189] The collimation lens 528 turns the probe beam L3 into a
parallel luminous flux. The probe beam L3 having passed through the
collimation lens 528 enters the condenser lens 524. The condenser
lens 524 condenses the probe beam L3 on the light-receiving surface
of the photodetector 525. The photodetector 525 is provided with a
band-pass filter 525a. The band-pass filter 525a transmits light
having a wavelength of 405 nm. Accordingly, it is possible to stray
light having a wavelength other than the wavelength of the probe
beam from entering the photodetector 525.
[0190] In this manner, the photodetector 525 detects the probe beam
L3 having passed through the polysilicon film 101b twice in the
optical system 503. Accordingly, it is possible to emphasize
transmittance unevenness. In addition, the focal point by the lens
523 and the focal point by the condenser lens 533 are at the same
position on the substrate 100. Accordingly, it is possible to
emphasize shot unevenness and to more properly evaluate the
crystalline state.
[0191] Note that, the probe beam L2 has passed through the
substrate 100 at the same position in the optical system 503. The
optical system 503 may be provided with a camera 530 that confirms
the focal points of the lens 523 and the condenser lens 533. The
camera 530 captures an image of the illumination region of the
probe beam L2 and its surroundings. The focal points can be
adjusted based on the image by the camera 530. The camera 530 may
be provided only at the time of installing the optical system
503.
[0192] FIG. 33 is a graph showing the average value and the
standard deviation of the detection signals acquired by the
photodetector 52. FIG. 33 shows a measurement result when the
energy density is changed in the range from 400 to 435 mJ/cm.sup.2
and at a pitch of 5 mJ/cm.sup.2. When the energy density is 420
mJ/cm.sup.2 and 425 mJ/cm.sup.2, the average values of the
detection signals are low. Thus, the OED is to be either 420
mJ/cm.sup.2 or 425 mJ/cm.sup.2.
[0193] However, the average values at 420 mJ/cm.sup.2 and 425
mJ/cm.sup.2 are nearly the same, and it is difficult to obtain the
OED from the average values. On the other hand, the standard
deviation at 420 mJ/cm.sup.2 is less than the standard deviation at
425 mJ/cm.sup.2. Thus, the OED can be set to 420 mJ/cm.sup.2. In
this manner, by using the average values and the standard
deviations of the detection values, it is possible to properly
determine the OED.
[0194] The present invention is not limited to the above-described
embodiments, various modifications can be made without departing
from the spirit and scope of the present invention.
[0195] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2016-163693, filed on
Aug. 24, 2016 and Japanese patent application No. 2017-112516,
filed on Jun. 7, 2017, the disclosure of which is incorporated
herein in its entirety by reference.
REFERENCE SIGNS LIST
[0196] 1 Laser annealing apparatus [0197] 11 Laser beam source
[0198] 12 Mirror [0199] 13 Projection lens [0200] 21 Probe beam
source [0201] 22 Mirror [0202] 23 Lens [0203] 24 Condenser lens
[0204] 25 Photodetector [0205] 26 Treatment apparatus [0206] 100
Substrate [0207] 101 Silicon film [0208] 300 Organic EL display
[0209] 310 Substrate [0210] 311 TFT layer [0211] 311a TFT [0212]
312 Organic layer [0213] 312a Organic EL light emitting device
[0214] 312b Partition wall [0215] 313 Color filter layer [0216]
313a Color filter (CF) [0217] 314 Sealing substrate [0218] 401
Glass substrate [0219] 402 Gate electrode [0220] 403 Gate
insulating film [0221] 404 Amorphous silicon film [0222] 405
Polysilicon film [0223] 406 Interlayer insulating film [0224] 407a
Source electrode [0225] 407b Drain electrode [0226] 408
Planarization film [0227] 409 Pixel electrode [0228] 410 TFT [0229]
PX Pixel
* * * * *