U.S. patent application number 11/316879 was filed with the patent office on 2006-07-13 for dry stripping equipment comprising plasma distribution shower head.
Invention is credited to Hoon-Ho Kim.
Application Number | 20060151115 11/316879 |
Document ID | / |
Family ID | 36652079 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060151115 |
Kind Code |
A1 |
Kim; Hoon-Ho |
July 13, 2006 |
Dry stripping equipment comprising plasma distribution shower
head
Abstract
A plasma distribution device for supplying plasma onto an object
in a chamber is provided. The device includes a tube for supplying
the plasma into the chamber, and a baffle installed under the tube
for controlling flow of the plasma supplied from the tube. The
baffle includes an upper shower head and a lower shower head, the
upper shower head having a center portion for reflecting the plasma
supplied from the tube, and a plurality of holes spaced apart from
each other around the center portion for uniformly distributing the
plasma.
Inventors: |
Kim; Hoon-Ho; (Suwon-si,
KR) |
Correspondence
Address: |
VOLENTINE FRANCOS, & WHITT PLLC
ONE FREEDOM SQUARE
11951 FREEDOM DRIVE SUITE 1260
RESTON
VA
20190
US
|
Family ID: |
36652079 |
Appl. No.: |
11/316879 |
Filed: |
December 27, 2005 |
Current U.S.
Class: |
156/345.34 |
Current CPC
Class: |
H01J 2237/3342 20130101;
H01J 37/3244 20130101; H01J 37/32633 20130101; G03F 7/427 20130101;
H01J 37/32623 20130101 |
Class at
Publication: |
156/345.34 |
International
Class: |
C23F 1/00 20060101
C23F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2005 |
KR |
2005-0002525 |
Claims
1. Dry stripping equipment comprising: a chamber in which a plasma
stripping process is carried out; a support disposed in the
chamber, and on which an object to be processed in the chamber is
to be seated; a tube having an end at which the tube opens into the
chamber and through which plasma is introduced into the chamber in
a given direction; and a baffle disposed in the chamber as
interposed between the tube and the support, the baffle including
an upper shower head and a lower shower head, the upper shower head
comprising a plate having a central portion, an upper surface and a
lower surface, the upper surface at the central portion of the
plate being disposed directly across from and exposed to said end
of the tube in the direction in which plasma is introduced into the
chamber, and the plate having a plurality of holes extending from
the top surface to the bottom surface thereof and which holes are
only present in the plate outside the central portion of the plate
and are spaced apart from each other beginning at the periphery of
the central portion of the plate, and the upper shower head and the
lower shower head extending across the chamber so as to divide the
chamber into a first space located between the plate of the upper
shower head and the end of the tube, a second space located between
the plate of the upper shower head and the lower shower head, and a
third space located between the lower shower head and the support,
whereby the plasma introduced into the chamber through the tube
directly impinges and is reflected from the central portion of the
plate in said first space so as to diffuse throughout said first
space, is distributed by the plate of the upper shower head into
said second space to the lower shower head, and is distributed by
the lower shower head into said third space.
2. The dry stripping equipment according to claim 1, wherein the
plate of the upper shower head and the lower shower head each have
an outer coating of sapphire.
3. Dry stripping equipment comprising: a chamber in which a plasma
stripping process is carried out; a support disposed in the
chamber, and on which an object to be processed in the chamber is
to be seated; a tube having an end at which the tube opens into the
chamber and through which plasma is introduced into the chamber in
a given direction; and a baffle disposed in the chamber as
interposed between the tube and the support, the baffle including
an upper shower head and a lower shower head, the upper shower head
consisting of a plate having a central portion, an upper surface
and a lower surface, and the plate having a plurality of holes
extending from the top surface to the bottom surface thereof and
which holes are only present in the plate outside the central
portion of the plate and are spaced apart from each other beginning
at the periphery of the central portion of the plate, and the plate
and the lower shower head extending across the chamber so as to
divide the chamber into a first space located between the plate and
the end of the tube, a second located between the plate and the
lower shower head, and a third space located between the lower
shower head and the support, and the entire upper surface of the
plate being exposed to said first space with the central portion of
the plate at said upper surface thereof being disposed directly
across from said end of the tube in the direction in which plasma
is introduced into the chamber, whereby the plasma introduced into
the chamber through the tube directly impinges and is reflected
from the central portion of the plate in said first space so as to
diffuse throughout said first space, is distributed through all of
the holes in the plate to the lower shower head, and is distributed
by the lower shower head into said third space.
4. The dry stripping equipment according to claim 3, wherein the
plate and the lower shower head each have an outer coating of
sapphire.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a semiconductor fabricating
apparatus. More particularly, the present invention relates to dry
stripping equipment using plasma for removing photoresist from a
wafer.
[0003] 2. Description of the Related Art
[0004] In general, a semiconductor device is fabricated by carrying
out a plurality of unit processes in succession. More specifically,
a typical semiconductor device is fabricated by subjecting a wafer
to photolithographic, diffusion, etching, and deposition processes.
Plasma is usually employed in the deposition process to deposit
material onto the wafer and in the etching process to etch material
on the wafer. A deposition process employing such plasma is
referred to as chemical vapor deposition. The etching processes
that employ plasma include sputtering and reactive ion etching
processes. Plasma is also employed in a dry stripping process to
remove photoresist deposited on the wafer in the photolithographic
process and cured as the result of the etching process.
[0005] The chemical vapor deposition process is advantageous in
that it can produce a thin film that is more uniform and provides
better step coverage than thin films produced by other existing
deposition processes. In addition, the deposition rate is higher.
Hence, chemical vapor deposition is widely utilized to form thin
films in the fabricating of semiconductor devices.
[0006] With respect to dry etching, such as sputter etching and
reactive ion etching, a wafer having an insulation film or metal
layer thereon, and a photoresist pattern (mask) exposing select
portions of the insulation film or metal layer, is loaded into an
airtight process chamber. Gas is introduced into the chamber, and a
high frequency or microwave power is applied to the chamber to
transform the gas into a plasma that etches the exposed portions of
the insulation film or metal layer. Dry etching is characterized in
that a cleaning process is not required after the etching process,
and the insulation film or metal layer is etched anisotropically.
Hence, dry etching is simpler to carry out than wet etching, and
dry etching can form fine patterns of a highly integrated circuit
which are superior to those which can be formed by wet etching.
[0007] Meanwhile, after the etching process has been completed, the
wafer is subjected to a stripping process for removing the
photoresist from the wafer. As compared to a wet stripping process,
the dry stripping process is advantageous in that it does not
require the handling of batches of liquid chemicals, it does not
present the concerns that are present when a wet etching bath or a
hood is employed, and the wafer is not exposed to chemicals or a
cleaning solution.
[0008] In dry stripping, the etched wafer which is transferred onto
a support in a chamber. The chamber is sealed once the wafer is
seated on the support. Subsequently, the interior of the chamber is
evacuated by a vacuum pump until a high degree of vacuum is
produced in the chamber. Next, plasma produced by a generator is
supplied into the chamber through a tube installed on a lid of the
chamber. The plasma is reflected by a reflector installed on a
central portion of an upper surface of a plate, which together
constitute an upper shower head. The reflected plasma is diffused,
and propagates downwardly through a plurality of holes in the plate
and a plurality of holes of a lower shower head. Hence, the plasma
is uniformly distributed over the wafer seated on the support, and
the photoresist is stripped off of the wafer by the plasma.
[0009] FIG. 1 illustrates an upper shower head of the conventional
stripping equipment. A reflector 45 is disposed on a central
portion of an upper surface of a plate 40 and is fixed thereto by
fixing pins 47. The reflector 45, the fixing pins 47, and the upper
shower head 40 are made of quartz, and the reflector 45 and the
plate 40 are coated with sapphire to prevent the reflector and
plate from being etched by the plasma. The fixing pins 47 are not
coated with sapphire due to technical reasons. Accordingly, the
fixing pins 47 are etched by the plasma, as shown in FIG. 2.
[0010] Specifically, the fixing pins 47 are gradually etched by the
plasma as the dry stripping progresses. After a period of time, the
fixing pins 47 no longer can secure the reflector 45 to the upper
surface of the plate 40 in the upper shower head. In this case, the
reflector 45 is moved from the central portion of the plate 40 by
the operation of the vacuum pump or by the plasma. Thus, the
reflector 45 stops up some of the holes 43 in the plate 40.
Accordingly, the plasma does not pass through the stopped up holes
43. As a result, the plasma is not uniformly distributed over the
lower shower head and hence, the plasma is not uniformly
distributed over the wafer such that a processing defect is
produced on the wafer.
[0011] When the above-described problem occurs in the equipment, a
considerable time is required to repair the equipment. This
detracts from the productivity in the overall process of
fabricating the semiconductor device.
SUMMARY OF THE INVENTION
[0012] Therefore, an object of the present invention is to provide
plasma dry stripping equipment capable of preventing plasma from
being non-uniformly distributed over an object to be processed.
[0013] In accordance with one aspect of the present invention, the
plasma dry stripping equipment comprises: a process chamber, a tube
for supplying plasma into the chamber, and a baffle for
distributing the plasma supplied from the tube, wherein the baffle
includes an upper shower head and a lower shower head, and the
upper shower comprises a plate having a central portion that
reflects the plasma supplied from the tube, and a plurality of
holes spaced apart from each other around the central portion for
uniformly distributing the plasma.
[0014] That is, the central portion of the upper surface of the
plate is disposed directly across from and is exposed to the end of
the tube from which plasma issues into the chamber. The holes in
the plate are only present in the plate outside the central portion
of the plate and are spaced apart from each other beginning at the
periphery of the central portion of the plate. Also, the upper
shower head and the lower shower head extend across the chamber so
as to divide the chamber into a first space located between the
plate of the upper shower head and the end of the tube, a second
space located between the plate of the upper shower head and the
lower shower head, and a third space located between the lower
shower head and the support. Thus, the plasma introduced into the
chamber through the tube directly impinges and is reflected from
the central portion of the plate so as to diffuse throughout the
first space. Then, the plasma is distributed by the plate of the
upper shower head to the lower shower head. From there, the plasma
is distributed by the lower shower head into the third space in
which the object to be processed is supported.
[0015] Basically, the upper shower head consists of the plate that
has the plasma distribution holes therein. In other words, the
upper shower head does not include a reflector that is discrete
from the plate having the plasma distribution holes. Thus, the
present invention obviates the problems associated with keeping
such a reflector secured to the plate. Moreover, the entire upper
surface of the plate is exposed, i.e., all of the holes in the
plate are unobstructed. Accordingly, plasma is distributed
uniformly.
[0016] Also, the plate of the upper shower head and the lower
shower head are coated with sapphire, so that the shower heads are
not etched by the plasma.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other features and advantages of the present
invention will become more apparent to those of ordinary skill in
the art by referring to the detailed description of the preferred
embodiments thereof made with reference to the attached drawings in
which:
[0018] FIG. 1 is a perspective view of an upper shower head of
conventional dry stripping equipment;
[0019] FIG. 2 is a similar perspective view but showing a case in
which fixing pins of the upper shower head are etched by
plasma;
[0020] FIG. 3 is a schematic longitudinal sectional view of dry
stripping equipment according to the present invention;
[0021] FIG. 4 is a perspective view of an upper shower head of the
dry stripping equipment according to the present invention; and
[0022] FIG. 5 shows data of the rate and uniformity of a
photoresist stripping process according to the present invention
and of a photoresist stripping process according to the prior art;
and
[0023] FIG. 6 shows data of particles present on wafers after
performing the stripping process according to the present invention
and after performing a stripping process according to the prior
art.
DETAILED DESCRITPION OF THE PREFERRED EMBODIMENTS
[0024] The preferred embodiments of the present invention will now
be described with reference to the FIGS. 3-6. Like reference
numbers designate like elements throughout the drawings.
[0025] Referring first to FIGS. 3 and 4, the dry plasma equipment
according to the present invention includes a chamber, a tube 115
for supplying plasma into the chamber, a baffle 130, and a slit
valve 129. The plasma is produced by a remote plasma generator (not
shown) disposed on the outside of the chamber. The interior of the
chamber is defined by a chamber lid 110 and a body 120. The tube
115 extends through the chamber lid 110.
[0026] The baffle 130 is installed in the chamber lid 110 under the
tube 115 to control the diffusion of the plasma. The baffle 130
includes an upper shower head 140 and a lower shower head 150.
[0027] The upper shower head 140 consists of a plate having a
central portion 147 for reflecting the plasma supplied from the
tube 115, and a plurality of holes 143 spaced apart from each other
around the central portion 147 for uniformly distributing the
plasma. The entire upper surface of the plate is exposed with the
central portion of the plate being disposed directly across from
the end of the tube 115 in the direction in which plasma is
introduced into the chamber. The plate constituting the upper
shower head 140 is coated with sapphire to prevent the upper shower
head from being etched by the plasma supplied from the tube
115.
[0028] The lower shower head 150 is disposed under the upper shower
head 140. The lower shower head 150 comprises a plate having a
plurality of holes 153 spaced apart from each other to uniformly
distribute the plasma supplied through the upper shower head 140.
The lower shower head 150 is also coated with sapphire to prevent
the lower shower head 150 from being etched by the plasma.
[0029] The baffle 130 extends across the chamber so as to divide
the chamber into a first space located between the plate of the
upper shower head 140 and the end of the tube 115, a second space
located between the plate of the upper shower head 140 and the
lower shower head 150, and a third space located between the lower
shower head 150 and the support 125.
[0030] A support 125 on which the wafer 10 to be processed is
seated under the lower shower head 150 is disposed in the third
space at the bottom of the body 120 of the chamber. One side of the
body 120 has an opening 127 through which the wafer 10 can pass. A
slit valve 129 is disposed on the outer side of the body 120 over
the opening 127 and is operable to open and close over the opening
127.
[0031] A dry stripping process performed by the dry etching
equipment will now be described in more detail.
[0032] Initially, the interior of the chamber is maintained at
atmospheric pressure. Then, the slit valve 129 uncovers the opening
127 in the body 120, and the wafer 10 is transferred onto the
support 125 through the opening 127. The transfer of the wafer 10
is achieved by transfer means (not shown) such as a robot. Once the
wafer 10 is seated on the support 125, the slit valve 129 closes
over the opening 127, and the interior of the chamber is evacuated
by a vacuum pump (not shown) until a high degree of vacuum prevails
inside the chamber.
[0033] Next, the tube 115 supplies plasma produced by the remote
plasma generator onto the central portion 147 of the plate
constituting the shower head 140, whereupon the plasma is reflected
by the central portion 147. The plasma diffuses throughout the
entire space above the shower head 140 because the space is
maintained in a high vacuum state. That is, the plasma is uniformly
distributed in the first space.
[0034] The plasma propagates downwardly through the holes 43 in the
plate and the holes 153 in the lower shower head 150. Hence, the
plasma is uniformly distributed on the wafer 10 seated on the
support 25. Accordingly, a dry stripping process is carried out by
the plasma.
[0035] Once the dry stripping process is completed, the interior of
the chamber is vented so that atmospheric pressure prevails in the
chamber. At this time, the slot valve 129 is opened to uncover the
opening 127, the processed wafer 10 is withdrawn from the chamber
by the transfer means, and a new wafer is loaded into the chamber.
The above-described process is then carried out on the new
wafer.
[0036] FIGS. 5 and 6 illustrate results of stripping processes
according to the present invention and according to the prior art.
In particular, FIG. 5 shows comparative data of the rate and
uniformity of the stripping processes, and FIG. 6 shows comparative
data of the production of particles after the stripping
processes.
[0037] In general, a stripping process is deemed satisfactory when
the rate at which the photoresist removed is 53000 .ANG./min to
65000 .ANG./min and the uniformity of the process is about 10%.
FIG. 5 shows that photoresist was removed at rates of 57582
.ANG./min and 53373 .ANG./min by two pieces of conventional plasma
stripping equipment, respectively, each having an upper shower head
comprising a plate and a reflector covering the central portion of
the upper surface of the plate. Both pieces of the conventional
stripping equipment were also able to execute dry stripping
processes having a uniformity of about 10%.
[0038] As is also shown in FIG. 5, photoresist was removed at rates
of 61562 .ANG./min, and 60517 .ANG./min by two pieces of plasma
stripping equipment, respectively, according to the present
invention. Both pieces of the plasma stripping equipment according
to the present invention were also able to execute dry stripping
processes having a uniformity of about 10%.
[0039] The abovementioned data thus shows that the rate at which
photoresist is removed and the uniformity of the stripping process
are within what are deemed normal operating parameters of
photoresist dry stripping equipment. Therefore, it is clear from
the data that plasma is adequately reflected from the upper shower
head of the present invention, which consists of a plate having
plasma distribution holes therethrough.
[0040] Moreover, no more than 30 particles should be produced as
the result of a dry stripping process.
[0041] FIG. 6 shows particles distributed on wafers after two
stripping processes performed using conventional dry stripping
equipment and dry stripping equipment according to the present
invention. Note, most of the particles shown on the wafers were
produced prior to the stripping process. The difference in the
number of particles counted pre- and post-stripping, i.e., the
number of particles produced as the result of the stripping process
is listed at the top of each drawing in the figure.
[0042] The results show that one particle was produced as the
result of a stripping process performed in the P/C (process
chamber) of one piece of the conventional dry stripping equipment,
and no particles were produced as the result of a stripping process
performed in the other piece of conventional dry stripping
equipment. The results also show that three particles were produced
as the result of a stripping process performed in the P/C of one
piece of the dry stripping equipment according to the present
invention, and no particles were produced as the result of a
stripping process performed in the other piece of dry stripping
equipment according to the present invention. Thus, the
abovementioned data shows that the number of particles produced
when the photoresist is removed by the present invention is within
an allowable range.
[0043] In short, the present invention is able to perform at nearly
the same level as the conventional dry stripping equipment even
though the upper shower head of the dry stripping equipment of the
present invention is not provided with a discrete reflector for
reflecting the plasma.
[0044] According to the present invention as described above, the
plasma is always uniformly distributed over an object to be
processed because there is no discrete reflector that could
potentially block the holes in the upper shower head.
[0045] That is, the dry stripping equipment of the present
invention is less likely to fail than the conventional equipment.
Thus, the present invention requires less maintenance and repair.
Accordingly, the productivity of the dry stripping equipment
according to the present invention is relatively high, thereby
making it more economical to manufacture a semiconductor
device.
[0046] In addition, the dry stripping equipment of the present
invention is less costly to fabricate than the prior art because
the present invention does not require a reflector that is discrete
from the plate constituting the upper shower head.
[0047] Finally, although the present invention has been described
above in connection with the preferred embodiments thereof, the
scope of the invention is not limited to the disclosed embodiments.
Rather, various modifications of the preferred embodiments will
become apparent to those skilled in the art. Accordingly, the true
spirit and scope of the invention is not defined by the detailed
description of the preferred embodiments but by the appended
claims.
* * * * *