U.S. patent application number 16/595995 was filed with the patent office on 2020-01-30 for plasma processing apparatus and plasma processing method.
The applicant listed for this patent is Tokyo Electron Limited. Invention is credited to Yasuhiro HAMADA, Yoshinobu HAYAKAWA, Akinobu KAKIMOTO, Satoshi MIZUNAGA, Mitsuhiro OKADA.
Application Number | 20200035496 16/595995 |
Document ID | / |
Family ID | 54935370 |
Filed Date | 2020-01-30 |
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United States Patent
Application |
20200035496 |
Kind Code |
A1 |
KAKIMOTO; Akinobu ; et
al. |
January 30, 2020 |
PLASMA PROCESSING APPARATUS AND PLASMA PROCESSING METHOD
Abstract
A plasma processing apparatus includes a chamber having a gas
inlet and a gas outlet; a plasma generator; and a controller
configured to cause: (a) providing a substrate including a
silicon-containing film and a mask formed on the film; (b) etching
the silicon-containing film through the mask to the first depth,
thereby forming a recess in the silicon-containing film; (c)
forming a protection film at least on the mask and a side wall of
the recess formed on the silicon-containing film after (a); and (d)
etching the silicon containing film through the mask to a second
depth, the second depth being greater than the first depth.
Inventors: |
KAKIMOTO; Akinobu;
(Yamanashi, JP) ; HAYAKAWA; Yoshinobu; (Miyagi,
JP) ; MIZUNAGA; Satoshi; (Iwate, JP) ; HAMADA;
Yasuhiro; (Yamanashi, JP) ; OKADA; Mitsuhiro;
(Yamanashi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tokyo Electron Limited |
Tokyo |
|
JP |
|
|
Family ID: |
54935370 |
Appl. No.: |
16/595995 |
Filed: |
October 8, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15310840 |
Nov 14, 2016 |
10460950 |
|
|
PCT/JP2015/066114 |
Jun 3, 2015 |
|
|
|
16595995 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01J 2237/334 20130101;
H01L 21/308 20130101; H01L 21/3065 20130101; H01J 37/32082
20130101; H01L 21/3083 20130101; H01L 21/31144 20130101; H01L
21/31116 20130101; H01L 21/3081 20130101 |
International
Class: |
H01L 21/3065 20060101
H01L021/3065; H01J 37/32 20060101 H01J037/32; H01L 21/311 20060101
H01L021/311; H01L 21/308 20060101 H01L021/308 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2014 |
JP |
2014-123164 |
Oct 2, 2014 |
JP |
2014-203619 |
Claims
1. A plasma processing apparatus, comprising: a chamber having a
gas inlet and a gas outlet; a plasma generator; and a controller
configured to cause: (a) providing a substrate including a
silicon-containing film and a mask formed on the film; (b) etching
the silicon-containing film through the mask to the first depth,
thereby forming a recess in the silicon-containing film; (c)
forming a protection film at least on the mask and a side wall of
the recess formed on the silicon-containing film after (a); and (d)
etching the silicon containing film through the mask to a second
depth, the second depth being greater than the first depth.
2. The plasma processing apparatus according to claim 1, wherein
the silicon-containing film is formed of a silicon-containing oxide
film, a silicon nitride film, or a stacked film of the
silicon-containing oxide film and the silicon nitride film.
3. The plasma processing apparatus according to claim 1, wherein
the steps (c) and (d) are performed in a same chamber.
4. The plasma processing apparatus according to claim 1, wherein
the step (c) is performed in non-plasma.
5. The plasma processing apparatus according to claim 1, wherein
the steps (c) and (d) are repeated multiple times.
6. The plasma processing apparatus according to claim 1, wherein
the method further includes performing a treatment process with any
of a single gas of monosilane and a mixed gas containing monosilane
after the step (c) and before the step (d).
7. The plasma processing apparatus according to claim 1, wherein
the protection film consists of at least two layers.
8. The plasma processing apparatus according to claim 1, wherein
the protection film is formed by supplying a film forming gas
containing carbon.
9. The plasma processing apparatus according to claim 8, wherein
the film forming gas contains hydrocarbon gas.
10. The plasma processing apparatus according to claim 8, wherein
the film forming gas contains ethylene gas.
11. The plasma processing apparatus according to claim 1, wherein
the plasma etching is performed with plasma generated by a gas
containing fluorocarbon.
12. The plasma processing apparatus according to claim 1, wherein
the plasma etching is performed with plasma generated by a
hexafluoro-1,3-butadiene gas.
13. The plasma processing apparatus according to claim 1, further
comprising: a gas supplying unit configured to supply a etching gas
and a film forming gas into the chamber.
14. The plasma processing apparatus according to claim 1, further
comprising: a gas supplying unit configured to supply a gas
containing fluorocarbon into the chamber.
15. The plasma processing apparatus according to claim 1, further
comprising: a gas supplying unit configured to supply a gas
containing carbon into the chamber.
16. The plasma processing apparatus according to claim 1, further
comprising: a gas supplying unit configured to supply a gas
containing silicon into the chamber.
17. A plasma processing method, the method comprising: (a)
providing a substrate including a silicon-containing film and a
mask formed on the film; (b) etching the film through the mask to
the first depth, thereby forming a recess in the film; (c) forming
a protection film at least on the mask and a side wall of the
recess formed in the silicon-containing film after (a); and (d)
etching the film through the mask to a second depth, the second
depth being greater than the first depth.
18. The plasma processing method according to claim 17, wherein the
film containing silicon is a stacked film of a silicon-containing
oxide film and a silicon nitride film.
19. The plasma processing method according to claim 17, wherein the
mask is formed of at least one selected from the group consisting
of polysilicon, amorphous carbon, amorphous silicon and
metal-containing material.
20. The plasma processing method according to claim 17, wherein the
protection film contains silicon.
21. The plasma processing method according to claim 17, wherein the
protection film contains carbon.
22. The plasma processing method according to claim 17, wherein the
step (c) initially forms a carbon-containing film and subsequently
forms a silicon-containing film.
23. The plasma processing method according to claim 17, wherein the
protection film has a thickness that becomes thinner toward a
bottom of the recess.
24. The plasma processing method according to claim 17, wherein the
step (b) continues before the recess has a bowing shape.
25. The plasma processing method according to claim 17, wherein the
plasma is capacitively coupled plasma.
26. The plasma processing method according to claim 17, wherein the
plasma is inductively coupled plasma.
27. The plasma processing method according to claim 17, wherein the
steps (c) and (d) are performed in a same chamber.
28. The plasma processing method according to claim 17, wherein the
steps (c) and (d) are performed in different chambers.
29. The plasma processing method according to claim 17, further
comprising: a gas supplying unit configured to supply a etching gas
and a film forming gas into the chamber.
30. The plasma processing method according to claim 17, further
comprising: a gas supplying unit configured to supply a gas
containing fluorocarbon into the chamber.
31. The plasma processing method according to claim 17, further
comprising: a gas supplying unit configured to supply a gas
containing carbon into the chamber.
32. The plasma processing method according to claim 17, further
comprising: a gas supplying unit configured to supply a gas
containing silicon into the chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of
U.S. patent application Ser. No. 15/310,840 filed on Nov. 14, 2016,
which is the National Stage of International Application No.
PCT/JP2015/066114 filed on Jun. 3, 2015, claiming priority based on
Japanese Priority Application No. 2014-123164 filed on Jun. 16,
2014, and Japanese Priority Application No. 2014-203619 filed on
Oct. 2, 2014, the entire contents of which are hereby incorporated
herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to substrate processing
systems and substrate processing methods.
BACKGROUND ART
[0003] In plasma etching of contact hole having high aspect ratio,
it is difficult for ion to reach a bottom of the contact hole as a
depth of the hole becomes greater. Therefore, not only the bottom
of the contact hole but also the side wall thereof is etched.
Consequently, a bowing shape is formed, in which a diameter
(referred to as Critical Dimension (CD) value) at upper side of the
hole is greater than the CD at lower side of the hole. Hence, a
technology is proposed, in which a desired film is formed on a side
wall of a pattern after the etching of the hole is completed so as
to repair a form of the pattern (e.g., Patent Document 1).
CITATION LIST
Patent Document
[0004] [Patent Document 1]: Japanese Laid-open Patent Publication
No. 2014-17438
SUMMARY OF INVENTION
Technical Problem
[0005] However, in a case where the film is formed after the
etching of the hole is completed, an etching rate may decrease as
the depth of the hole becomes greater because of the decrease in
the number of ions in the plasma that reaches the bottom of the
hole. Consequently, the aspect ratio becomes low, and desired
characteristic of a semiconductor device may not be achieved.
[0006] An object of an aspect of present invention is to perform a
favorable etching process while the formation of the bowing shape
is suppressed.
Solution to Problems
[0007] According to an embodiment of the present invention, there
is provided a substrate processing system including an etching
apparatus configured to supply a gas containing fluorocarbon to
generate plasma so as to perform an etching process on a film
including silicon formed on a substrate, wherein the etching
process is performed by using plasma through a mask formed on the
film including silicon; a film forming apparatus configured to
supply a gas containing carbon so as to form a film including
carbon on the etched film including silicon, wherein the film
forming apparatus is provided separately from the etching
apparatus, the etching apparatus performing, a first etching step
in which the film including silicon is partway etched by using
plasma; and a second etching step in which the film including
silicon, on which the film including carbon is formed, is further
etched by using plasma, the film forming apparatus performing a
film forming step in which the film including carbon is formed,
without generating plasma, on the film including silicon on which
the first etching step has been performed.
Advantageous Effects of Invention
[0008] According to an aspect of the present invention, it is
possible to perform a favorable etching process while the formation
of the bowing shape is suppressed.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is an example configuration of the substrate
processing system.
[0010] FIG. 2 is a longitudinal cross sectional view of the
substrate processing system 1 (including PC1 and PC2).
[0011] FIG. 3A is a diagram illustrating a bowing shape.
[0012] FIG. 3B is another diagram illustrating the bowing
shape.
[0013] FIG. 4 is a diagram illustrating a substrate processing
method.
[0014] FIG. 5 is a diagram illustrating examples of carbon
film.
[0015] FIG. 6 is a diagram illustrating an example effect of the
substrate processing method.
[0016] FIG. 7 is a diagram illustrating a substrate processing
method of variation 1.
[0017] FIG. 8 is a diagram illustrating an example effect of the
substrate processing method of variation 1.
[0018] FIG. 9 is a diagram illustrating an example effect of a
substrate processing method of variation 2.
DESCRIPTION OF EMBODIMENTS
[0019] Herein below, embodiments of the present invention will be
described with reference to the accompanying drawings.
Additionally, in the present specification and drawings, identical
reference numerals will be applied to elements or the like that
have substantially similar functions and configurations to those in
another embodiment, and descriptions thereof may be omitted.
Example Configuration of Substrate Processing System
[0020] First, an example configuration of a substrate processing
system 1 of an embodiment of the present invention will be
described with reference to FIG. 1. FIG. 1 is an example
configuration of the substrate processing system 1 of the present
embodiment. The substrate processing system 1 includes a process
chamber (hereinafter simply referred to as "PC") PC1 that processes
a substrate in-situ and a process chamber PC2 that processes a
substrate ex-situ. The PC1 and the PC2 are separately provided as
discrete chambers.
[0021] The PC1 and the PC2 are connected via a transfer chamber
(hereinafter referred to as "TC") and a conveyance mechanism 2. The
PC1 and the TC, and the TC and the conveyance mechanism 2 are
connected via a gate valve G so that the connection is open/close
by the gate valve G. The interiors of the PC1 and TC are in a
reduced pressure state. By carrying in and carrying out the
substrate by opening and closing the gate valve G, the inside of
the PC1 is isolated from outside air to keep a predetermined vacuum
degree.
[0022] A conveyance apparatus 52 for holding and carrying in/out
the substrate is provided in the TC. The conveyance apparatus 52
includes a rotation/expansion and contraction unit 53 that is
rotatable and able to be expanded and contracted and two blades 54a
and 54b that hold the substrate at the front end of the
rotation/expansion and contraction unit 53. The blades 54a and 54b
are mounted on the rotation/expansion and contraction unit 53 so
that respective blades face opposite sides.
[0023] The conveyance mechanism 2 conveys the substrate between the
TC and the PC2. For example, the conveyance mechanism 2 may be
configured so that the conveyance mechanism 2 runs on a rail with
holding the substrate on a tray disposed in the conveyance
mechanism 2.
[0024] The PC1 generates plasma, and serves as an etching apparatus
for performing etching process on a film formed on the substrate by
using the plasma. The PC1 may serve as an ashing apparatus for
performing ashing process on the film formed on the substrate by
using plasma.
[0025] PC2 is a film forming apparatus for forming a film on the
substrate without using plasma. In the present embodiment, the PC2
serves as a thermal CVD (Chemical Vapor Deposition) apparatus for
forming a carbon film on the substrate by using heat. However, the
thermal CVD apparatus is not a limiting example of the PC2. Any
types of apparatus may be chosen as long as the apparatus can
uniformly form a film inside (at least side wall of) a pattern on
the substrate etched by the PC1.
[0026] The substrate processing system 1 includes a control unit 40
for controlling an etching process, a film forming process, and an
ashing process of the substrate and a conveyance process of the
substrate. Control programs for performing the etching process, the
film forming process, the ashing process, and the conveyance
process, and processing recipe in which respective processing
conditions are set are stored in a storage unit 42. The storage
unit 42 may be a hard disk, or may be a portable recording medium
such as a CDROM (Compact Disc Read Only Memory), a DVD (Digital
Versatile Disk), and a flash memory. Also, for example, the
processing recipe may be transmitted from another apparatus through
a dedicated line if needed.
[0027] For example, the control unit 40 performs the etching
process, the film forming process, the ashing process, and the
conveyance process, etc., according to the processing recipe stored
in the storage unit 42 in response to user's instruction input
through a user interface 41.
Example Configuration of PC1/PC2
[0028] <PC1: Etching Apparatus>
[0029] An example configuration of the PC1 and the PC2 of the
present embodiment is briefly described with reference to FIG. 2.
FIG. 2 is a longitudinal cross sectional view of the substrate
processing system 1 (including PC1 and PC2) of the present
embodiment. However, FIG. 2 illustrates a non-limiting example
configuration of PC1 and PC2. For example, the PC1 is exemplified
as a Capacitively Coupled Plasma (CCP) processing apparatus.
However, the configuration of PC1 may be applied to other substrate
processing apparatuses. An Inductively Coupled Plasma (ICP)
processing apparatus, a CVD (Chemical Vapor Deposition) apparatus
using a radial line slot antenna, a Helicon Wave Plasma (HWP)
processing apparatus, and an Electron Cyclotron Resonance Plasma
(ECR) processing apparatus may be included in the other substrate
processing apparatuses.
[0030] The PC1 and the TC perform the process and conveyance of the
substrate under a reduced pressure while the conveyance mechanism 2
and the PC2 perform the process and conveyance of the substrate
under an atmospheric pressure. The PC1 includes processing chamber
made of aluminum, etc., having an anodized surface. A mounting
table 12 for mounting the substrate W is disposed inside the PC1. A
high frequency power supply 14 is connected to the mounting table
12, and high frequency power at a predetermined frequency (e.g. 60
MHz) for generating plasma is supplied from the high frequency
power supply 14.
[0031] A shower head 16 is disposed at a ceiling of the PC1. Gas is
supplied in shower-like form from a plurality of gas supply holes
18 formed at lower portion of the shower head 16. In the present
embodiment, a gas containing fluorocarbon is supplied, and a film
including silicon formed on the substrate is etched by the
generated plasma.
[0032] An etching gas may be a single gas of fluorocarbon (CF) gas,
or may be a mixed gas containing fluorocarbon gas. The etching gas
may include hexafluoro-1,3-butadiene C.sub.4F.sub.6 gas as the gas
containing fluorocarbon.
[0033] After the film including silicon formed on the substrate W
is etched in the PC1, the substrate W is carried into the PC2 by
using the conveyance apparatus 52 of the TC and the conveyance
mechanism 2.
[0034] <PC2: Thermal CVD Apparatus>
[0035] The PC2 includes a cylindrical outer wall 22 having a
ceiling and an inner wall 24 provided inside the outer wall 22. For
example, the outer wall 22 and the inner wall 24 are made of
quartz. A plurality of substrates W are stored in a processing
chamber 30 inside the inner wall 24. The PC2 performs a film
forming process collectively on a plurality of substrates W. The
outer wall 22 and the inner wall 24 are separated from each other
having a circular space 26 therebtween, and coupled to a base
member 28 at respective lower ends.
[0036] In the present embodiment, a gas containing carbon (C) is
supplied as a film forming gas. The supplied gas containing carbon
flows from lower side to upper side of the processing chamber 30
being sucked by the circular space 26 to be exhausted.
[0037] The film forming gas may be a single gas containing carbon,
or may be a mixed gas including the gas containing carbon. The film
forming gas may include ethylene (C.sub.2H.sub.4) gas or other
carbon (C.sub.xH.sub.y) gas as the gas containing carbon. The film
forming gas may include chlorine (Cl.sub.2) gas as a thermal
decomposition temperature decreasing gas. Also, the film forming
gas may include an inactive gas such as nitrogen (N.sub.2) gas. The
PC2 thermally decomposes the film forming gas to form a film
including carbon on the film including silicon formed on the
substrate. The PC2 may be a single-wafer film forming
apparatus.
[0038] Hereinabove, an example configuration of the PC1 and the PC2
is described. According to the substrate processing system 1 of the
present embodiment, firstly, the substrate W is carried into the
PC1 and the etching process is performed by the PC1. Then, the
substrate W is carried into the PC2, and carbon film forming
process is performed by the PC2. Further, the substrate is carried
into the PC1, and the etching process is performed again by the
PC1. Finally, the carbon film is removed by the PC1.
[0039] <Bowing Shape>
[0040] In the following, the bowing shape formed in an etching
pattern will be described with reference to FIG. 3A and FIG. 3B. As
illustrated in FIG. 3A, on the silicon substrate 125, a silicon
oxide (SiO.sub.2) film 126, a silicon nitride (SiN) film 127, and a
polysilicon mask 128 are formed.
[0041] In the present embodiment, the silicon oxide (SiO.sub.2)
film is exemplified as a film including silicon that is an etching
object film. However, this is not a limiting example of the film
including silicon that is the etching object film. A
silicon-containing oxide (SiO.sub.x) film, silicon nitride (SiN)
film, or laminated film of the silicon-containing oxide film and
the silicon nitride film may be used. The mask may be an amorphous
carbon mask, or a metal-containing mask.
[0042] A hole-shaped or line-shaped pattern as desired is formed on
the polysilicon mask 128. In a case where the silicon oxide film
126 is etched into a desired shape such as hole-shape, amount of
radical in plasma reaching a bottom of the hole decreases as the
depth of the etched hole becomes greater. Therefore, not only the
bottom of a contact hole but also side portion thereof is etched.
Consequently, as illustrated in FIG. 3B, the bowing shape is
formed, in which bowing CD at a lower portion of the hole becomes
greater than a top CD at upper portion of the hole. In a case where
the etching pattern is in a bowing shape, favorable device
characteristics are unlikely to be obtained in comparison to a case
where the etching pattern is in a vertical shape as illustrated in
FIG. 3A.
[0043] Therefore, the substrate processing system 1 of the present
embodiment performs a substrate processing method, in which the
formation of the bowing shape is suppressed while favorable etching
process can be performed. In the following, the substrate
processing method performed by the substrate processing system 1 of
the present embodiment will be described with reference to FIG.
4.
[0044] <Substrate Processing Method>
[0045] FIG. 4 illustrates the substrate processing method of the
present embodiment. FIG. 4(a) illustrates the silicon oxide film
126 formed on the silicon substrate 125 before being etched. The
silicon oxide film 126, the silicon nitride film 127, and the
polysilicon mask 128 are formed on the silicon substrate 125.
Additionally, the polysilicon mask 128 may be the amorphous carbon
mask, or the metal-containing mask. Also, the silicon nitride film
127 may not be included.
[0046] <Half Etching>
[0047] In the substrate processing method of the present
embodiment, first, the silicon substrate 125 is carried into the
PC1. The silicon nitride film 127 and the silicon oxide film 126
are etched in the PC1. As illustrated in FIG. 4(B), the silicon
oxide film 126 is partway etched in the PC1 (first etching step:
half etching). "partway etched" means not only that the silicon
oxide film 126 is etched in a depth direction to approximately half
depth but also that the silicon oxide film 126 is etched in a depth
direction to an extent without forming the bowing shape.
[0048] An example etching process condition is that the pressure is
2.66 Pa, the frequency of the high frequency power HF is 60 MHz,
the power thereof is 1200 W, and the gas is mixture of
C.sub.4F.sub.6 gas, C.sub.4F.sub.8 gas, Ar gas, and O.sub.2
gas.
[0049] <Carbon Film Forming>
[0050] Then, the silicon substrate 125 is carried from the PC1 to
the PC2. As illustrated in FIG. 4(c), the carbon film 130 is formed
on the etched silicon oxide film 126 in the PC2. Thus, the carbon
film 130 is uniformly formed on the inner wall of the pattern
formed on the silicon oxide film 126 (film forming step).
Additionally, the film formed on the silicon oxide film 126 may not
be carbon film 130 but a film including carbon.
[0051] An example process condition of the carbon film forming is
that the pressure is 997 Pa, the temperature is 400.degree. C., and
the gas is mixture of C.sub.2H.sub.4 gas and Cl.sub.2 gas.
[0052] FIG. 5 is a diagram illustrating examples of carbon films
formed by the thermal CVD apparatus used as the PC2 of the present
embodiment. According to a graph illustrated in FIG. 5, a thickness
of the carbon film 130 illustrated in FIG. 5(A) becomes 4.7 nm at
film forming time 50 min., while a thickness of the carbon film 130
illustrated in FIG. 5(B) becomes 10.3 nm at film forming time 90
min. Regarding both carbon films 130 formed on the silicon oxide
films 126 illustrated in FIG. 5(A) and FIG. 5(B), the carbon film
130 with uniform thickness is formed on side walls and bottom walls
of the etching pattern formed on the silicon oxide film 126.
[0053] According to a relationship between the film forming time
and the thickness of the carbon film illustrated in the graph of
FIG. 5, 30 min. of the film forming time is required to form the
carbon film 130 of the present embodiment because a required
thickness of the carbon film 130 is 1 nm-2 nm.
[0054] Additionally, it is conceivable that the film forming step
illustrated in FIG. 4(c) may be performed in-situ in the PC1.
However, the uniformity of thickness of the carbon film 130 is
important when the carbon film 130 whose thickness is 1 nm-2 nm is
formed.
[0055] On the other hand, in a case where the carbon film 130 is
formed by using plasma in the PC1, the carbon film 130 becomes
thinner at bottom side of the etching pattern than at upper side
thereof because the ion is unlikely to enter into the bottom side
of the etching pattern, and the like. Accordingly, it is difficult
to form the carbon film 130 with uniform thickness on the silicon
oxide film 126. Hence, it is preferable that the film forming step
of FIG. 4(c) is performed in non-plasma environment (without using
plasma) to form the carbon film 130.
[0056] <Full Etching>
[0057] Referring back to FIG. 4(c), the silicon substrate 125 is
carried from the PC2 to the PC1 after forming the film. As
illustrated in FIG. 4(d), the silicon oxide film 126 is further
etched in the PC1 (second etching step: full etching). In the full
etching, the carbon film 130 serves as a protection film formed on
the side wall of the silicon oxide film 126, thereby suppressing
formation of the bowing shape in the etching pattern.
[0058] The process condition of the etching in FIG. 4(d) may be the
same as that in FIG. 4(b). The process condition of the etching in
FIG. 4(d) may be different from that in FIG. 4(b) as long as a gas
including fluorocarbon is supplied into the PC1.
[0059] In the second etching step, in the PC1, the etching of the
silicon oxide film 126 may be finished when the silicon oxide film
126 is fully etched and the silicon substrate 125, which is a
ground layer, is exposed. The etching of the silicon oxide film 126
may be finished when a combination of the second etching step (FIG.
4(d)) and the film forming step (FIG. 4(c)) are performed in the
PC1 and the PC2 a predetermined times repeatedly.
[0060] <Ashing>
[0061] Then, as illustrated in FIG. 4(e), the ashing process is
performed in the PC1 after the second etching step, thereby
removing the carbon film 130 (second ashing step). In the ashing,
oxygen plasma generated from oxygen gas may be used.
[0062] Hereinabove, the substrate processing method using the
substrate processing system 1 is described. In the following, an
example effect of the substrate processing method of the present
embodiment will be described with reference to FIG. 6.
Example Effect
[0063] FIG. 6 is a diagram illustrating an example effect of the
substrate processing method of the present embodiment. FIG. 6(b) is
a diagram illustrating the pattern after the half etching (FIG.
4(b)). FIG. 6(f) is a diagram illustrating the pattern after the
full etching without forming the carbon film. FIG. 6(e) is a
diagram illustrating the pattern after the full etching (FIG. 4(d))
with the carbon film whose thickness is 1 nm. FIG. 6(h) is a
diagram illustrating the pattern after the full etching, where the
full etching is performed after forming the carbon film whose
thickness is 1 nm and further performing treatment with monosilane
(SiH.sub.4). Additionally, FIG. 6 illustrates the example in a case
where the silicon nitride film 127 is not laminated.
[0064] In the pattern after the half etching illustrated in FIG.
6(b), the top CD is 43.8 nm and the bowing CD is 46.9 nm.
[0065] In the pattern after the full etching without forming the
carbon film illustrated in FIG. 6(f), the top CD is 49.7 nm and the
bowing CD is 56.2 nm. In the pattern after full etching with 1
nm-carbon film illustrated in FIG. 6(e), the top CD is 48.9 nm and
the bowing CD is 52.8 nm.
[0066] In the pattern after full etching with 1 nm-carbon film and
monosilane (SiH.sub.4) treatment illustrated in FIG. 6(h), the top
CD is 48.7 nm and the bowing CD is 51.4 nm.
[0067] As described above, the bowing CD is improved in a case
where the carbon film is formed than a case where the carbon film
is not formed. That is, when the carbon film is formed during the
etching, the carbon film serves as the protection film to suppress
the bowing shape formed in the etching.
[0068] Moreover, the bowing CD is further improved in a case where
treatment with monosilane (SiH.sub.4) is performed after than a
case where the carbon film is not formed and a case where the
carbon film whose thickness is 1 nm is formed. It is conceived that
the film including silicon formed on the carbon film serves as the
protection film as well as the carbon film to suppress the bowing
shape.
[0069] Additionally, in the treatment after forming the carbon
film, a single gas of monosilane (SiH.sub.4) or mixture of
monosilane gas and dilution gas (N.sub.2 gas, H.sub.2 gas, etc.)
may be used.
[0070] As described above, according to the substrate processing
method of the present embodiment, by performing a carbon film
forming step during the etching step, the silicon oxide film 126 is
protected by the carbon film 130 in the remaining etching step to
suppress the bowing shape. Consequently, the etching shape can be
vertical and favorable device characteristics can be obtained.
[0071] <Variation 1>
[0072] In the following a substrate processing method of variation
1 will be described with reference to FIG. 7 and FIG. 8. FIG. 7 is
a diagram illustrating the substrate processing method of variation
1. FIG. 8 is a diagram illustrating an example effect of the
substrate processing method of variation 1.
[0073] The substrate processing method of variation 1 illustrated
in FIG. 7 is different from the substrate processing method
illustrated in FIG. 4 in that an ashing step illustrated in FIG.
7(g) is inserted between the half etching step illustrated in FIG.
4(b) and FIG. 7(b) and the film forming step illustrated in FIG.
4(c) and FIG. 7(c).
[0074] As illustrated in FIG. 7(b), reaction product 131 of polymer
generated through the etching is deposited on the polysilicon mask
128 after the half etching is performed on the silicon oxide film
126. Therefore, the film forming step illustrated in FIG. 7(c) is
preferably performed after removing the deposited reaction product
131 in the ashing step illustrated in FIG. 7(g). In the ashing step
(first ashing step) illustrated in FIG. 7(g) and in the ashing step
(second ashing step) illustrated in FIG. 7(e), oxygen plasma
generated from oxygen gas may be used.
[0075] In this way, the carbon film can be more uniformly formed by
removing the reaction product 131 deposited on the polysilicon mask
128.
Example Effect
[0076] An example effect of the substrate processing method of
variation 1 and an example effect of thickness of the carbon film
will be described with reference to FIG. 8. Additionally, FIG. 8
illustrates examples in a case where the silicon nitride film 127
is laminated.
[0077] In "case 1" illustrated in a leftmost portion of FIG. 8, the
pattern after the half etching (200 seconds) illustrated in FIG.
7(b) and further the ashing (first ashing step) illustrated in FIG.
7(g) is performed is illustrated.
[0078] In "case 2", the pattern after the full etching (350
seconds) without performing the half etching is performed and
further the ashing is performed is illustrated.
[0079] In "case 3", the pattern is illustrated, where the pattern
of "case 3" is formed through the half etching (200 seconds), the
ashing, the carbon film (whose thickness is 1 nm) forming, the full
etching (150 seconds), and the ashing.
[0080] In "case 4", the pattern is illustrated, where the pattern
of "case 4" is formed through the half etching (200 seconds), the
ashing, the carbon film (whose thickness is 2 nm) forming, the full
etching (150 seconds), and the ashing.
[0081] The top CD is 55.6 nm in case 2, 52.9 nm in case 3, and 54.2
nm in case 4. The bowing CD is 65.6 nm in case 2, 58.2 nm in case
3, and 57.5 nm in case 4.
[0082] Thus, the bowing shape can be suppressed in a case where the
carbon film 130 whose thickness is greater than or equal to 1 nm is
formed than a case where the carbon film 130 is not formed.
[0083] Also, the bowing shape can be more certainly suppressed in a
case where the carbon film 130 whose thickness is 2 nm is formed
than a case where the carbon film 130 whose thickness is 1 nm is
formed.
[0084] As described above, according to the substrate processing
method of variation 1, by performing the ashing after the half
etching, the reaction product 131 deposited on the polysilicon mask
128 can be removed. In this way, the carbon film can be more
uniformly formed on the inner wall of the etching pattern in the
film forming step after the ashing. Consequently, the bowing shape
can be effectively suppressed in the remaining etching step.
[0085] <Variation 2>
[0086] In the following, the substrate processing method of
variation 2 will be described with reference to FIG. 9. FIG. 9 is a
diagram illustrating an example effect of the substrate processing
method of variation 2. In the substrate processing methods of
above-described embodiment and variation 1, the carbon film is
formed as the protection film. On the other hand, in the substrate
processing method of variation 2, a silicon film is formed instead
of the carbon film.
[0087] Specifically, a silicon film forming step is performed
instead of the carbon film forming step illustrated in FIG. 7(c)
after the half etching step illustrated in FIG. 7(b) and the ashing
step illustrated in FIG. 7(g) are sequentially performed. According
to the step, the silicon film is formed as a protection film
instead of the carbon film 130 illustrated in FIG. 7(c). Then, the
full etching step illustrated in FIG. 7(d) is performed.
[0088] FIG. 9 is a diagram illustrating a result of the substrate
processing method of variation 2. The bowing CD after the half
etching in a case where the protection film is not formed, the
bowing CD after the full etching in a case where the protection
film is formed, and bowing CDs after the full etching in a case
where the protection film is formed are described in a line before
the last line of FIG. 9. As cases where the protection film is
formed, cases where the carbon (C) films whose thickness are 2 nm
and 3 nm are formed and a case where a silicon (Si) film whose
thickness is 3 nm is formed are described. Also, in the last line
of FIG. 9, differences between bowing CDs after the full etching in
a case where the protection film is not formed and the bowing CDs
after the full etching in a case where the protection film is
formed are described.
[0089] Additionally, an example process condition of the silicon
film forming is that the pressure is 133 Pa (1 Torr), the
temperature is 380.degree. C., the gas is a mixed gas containing
Si.sub.2H.sub.6/N.sub.2.
[0090] As described above, the bowing shape can be suppressed in a
case where the carbon film or the silicon film is formed, as a
protection film, after the half etching in comparison to a case
where the full etching is performed without forming the protection
film.
[0091] Also, according to the result illustrated in FIG. 9, the
bowing shape is hardly formed in a case where the carbon film whose
thickness is 3 nm is formed as the protection film after the half
etching. Also, according to the result illustrated in FIG. 9,
almost equal effect of suppression of the bowing shape can be
obtained in a case where the carbon film whose thickness is 2 nm is
formed as the protection film and in a case where the silicon film
whose thickness is 3 nm is formed as the protection film.
[0092] As described above, the bowing shape can be suppressed both
by the carbon film and by the silicon film. However, taking the
throughput into account, the bowing shape can be more effectively
suppressed by forming the carbon film as the protection film than
forming the silicon film.
[0093] Additionally, although in the substrate processing method of
variation 2, the silicon film is formed as the protection film
instead of the carbon film, this is not a limiting example. For
example, two or more laminated layers of the carbon film and the
silicon film may be formed as the protection film. In this case,
the carbon film may be formed prior to the silicon film, or the
silicon film may be formed prior to the carbon film. Also, film
forming processes for forming the laminated layer of the carbon
film and the silicon film may be performed subsequently in the same
chamber of the PC2 illustrated in FIG. 1, where the process
condition such as the type of gas is changed.
[0094] Additionally, in variation 2, in the PC2, a treatment with a
single gas of monosilane (SiH.sub.4) or mixed gas containing
monosilane may be also performed after the film forming step for
forming the silicon film or mixture of the silicon film and the
carbon film and before the full etching.
[0095] Herein above, although the substrate processing system and
the substrate processing method have been described with respect to
a above described embodiment for a complete and clear disclosure,
the substrate processing system and the substrate processing method
are not to be thus limited but are to be construed as embodying all
modifications and alternative constructions within a range of the
present invention.
[0096] Also, the substrate processing system may process various
types of substrates such as a wafer, a large substrate used for a
FPD (Flat Panel Display) and a substrate used for EL element or
solar battery.
REFERENCE SIGNS LIST
[0097] 1: substrate processing system [0098] 2: conveyance
mechanism [0099] 12: mounting table [0100] 14: high frequency power
supply [0101] 16: shower head [0102] 22: outer wall [0103] 24:
inner wall [0104] 30: processing chamber [0105] 40: control unit
[0106] 42: storage unit [0107] 52: conveyance apparatus [0108] 125:
silicon substrate [0109] 126: silicon oxide film [0110] 127:
silicon nitride film [0111] 128: polysilicon mask [0112] 130:
carbon film [0113] 131: reaction product [0114] PC1 and PC2:
process chambers [0115] TC: transfer chamber [0116] T: top CD
[0117] B: bowing CD
* * * * *