U.S. patent application number 11/225504 was filed with the patent office on 2006-04-13 for cleaning method and cleaning apparatus for performing the same.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Kyung-Hyun Kim, Chang-Hyeon Nam, Hong-Seong Son.
Application Number | 20060076034 11/225504 |
Document ID | / |
Family ID | 36144059 |
Filed Date | 2006-04-13 |
United States Patent
Application |
20060076034 |
Kind Code |
A1 |
Nam; Chang-Hyeon ; et
al. |
April 13, 2006 |
Cleaning method and cleaning apparatus for performing the same
Abstract
A cleaning apparatus includes upper and lower nozzle assemblies
supplying a cleaning liquid to edge and bottom sections of a
semiconductor substrate. The upper nozzle assembly has a first
nozzle supplying the cleaning liquid onto the edge section, and
second and third nozzles supplying a nitrogen gas for preventing
the cleaning liquid from moving into a center portion of the
semiconductor substrate. The cleaning liquid supplied to the edge
section flows from the edge section towards a side section of the
semiconductor substrate due to the rotation of the semiconductor
substrate. An ultrasonic wave generator is provided above the edge
section for generating ultrasonic waves. The ultrasonic waves are
applied to the cleaning liquid supplied onto the edge and bottom
sections, thereby improving the cleaning efficiency. The cleaning
apparatus has a guide to guide the cleaning liquid supplied to the
edge section toward the side section. The cleaning apparatus may
effectively remove impurities from the edge, side and bottom
sections of the semiconductor substrate.
Inventors: |
Nam; Chang-Hyeon;
(Gyeonggi-do, KR) ; Son; Hong-Seong; (Gyeonggi-do,
KR) ; Kim; Kyung-Hyun; (Seoul, KR) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
|
Family ID: |
36144059 |
Appl. No.: |
11/225504 |
Filed: |
September 13, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10281707 |
Oct 28, 2002 |
6983755 |
|
|
11225504 |
Sep 13, 2005 |
|
|
|
Current U.S.
Class: |
134/2 ; 134/1;
134/26; 134/3 |
Current CPC
Class: |
B08B 3/12 20130101; H01L
21/67051 20130101; Y10S 134/902 20130101; H01L 21/02052
20130101 |
Class at
Publication: |
134/002 ;
134/001; 134/003; 134/026 |
International
Class: |
B08B 3/12 20060101
B08B003/12; C03C 23/00 20060101 C03C023/00; B08B 3/00 20060101
B08B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2001 |
KR |
2001-74311 |
Claims
1. A method for cleaning a semiconductor substrate, the method
comprising the steps of: a) rotating the semiconductor substrate;
b) supplying a cleaning liquid to an edge section of the
semiconductor substrate for cleaning the edge section and a side
section of the semiconductor substrate; and c) applying an
ultrasonic wave to the cleaning liquid supplied to the edge
section.
2. The method as claimed in claim 1, wherein the cleaning liquid is
supplied from a center portion of the semiconductor substrate
toward the edge section at an incident angle of 30 to 60
degrees.
3. The method as claimed in claim 1, wherein, during the step of
supplying the cleaning liquid to the edge section, a nitrogen gas
stream is directed onto a first section which is spaced apart from
the edge section in a direction of a center portion of the
semiconductor substrate by a first predetermined distance to
restrict the cleaning liquid from moving toward the center
portion.
4. The method as claimed in claim 3, wherein the nitrogen gas
stream is directed onto the first section at an incident angle of
30 to 60 degrees from the center portion toward the edge
section.
5. The method as claimed in claim 3, wherein, during the step of
supplying the cleaning liquid to the edge section, a second
nitrogen gas stream is directed onto a second section which is
spaced apart from the edge section in the direction of the center
portion by a second predetermined distance to secondarily restrict
the cleaning liquid from moving toward the center portion.
6. The method as claimed in claim 6, wherein the second nitrogen
gas stream is directed onto the second section at an incident angle
of 15 to 30 degrees from the center portion towards the edge
section.
7. The method as claimed in claim 1, further comprising the step of
supplying a second cleaning liquid to a bottom section of the
semiconductor substrate simultaneously with the step of supplying
the cleaning liquid to the edge section.
8. The method as claimed in claim 7, wherein the cleaning liquid
and second cleaning liquid are any one selected from the group
consisting of deionized water, a mixture of HF and deionized water,
a mixture of NH.sub.4OH, H.sub.2O.sub.2 and deionized water, a
mixture of NH.sub.4F, HF, and deionized water, and a mixture of
H.sub.3PO.sub.4 and deionized water.
9. The method of claim 1, wherein the cleaning liquid is any one
selected from the group consisting of deionized water, a mixture of
HF and deionized water, a mixture of NH.sub.4OH, H.sub.2O.sub.2 and
deionized water, a mixture of NH.sub.4F, HF, and deionized water,
and a mixture of H.sub.3PO.sub.4 and deionized water.
10-23. (canceled)
Description
RELATED APPLICATIONS
[0001] The present application claims priority from Korean Patent
Application No. 2001-74311, filed Nov. 27, 2001, the disclosure of
which is hereby incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and apparatus for
cleaning semiconductor substrates and, more particularly, to a
method and an apparatus for cleaning an edge section, a side
section, and a bottom section of a semiconductor substrate.
BACKGROUND OF THE INVENTION
[0003] Generally, semiconductor devices are manufactured by
sequentially performing unit processes, such as deposition,
photolithography, etching, ion implantation, polishing, cleaning
and drying processes, on a semiconductor substrate. Among the above
unit processes, the cleaning process is carried out after each unit
process has been finished so as to remove the residue remaining on
the semiconductor substrate. Recently, as designs tend to require a
micro-sized pattern, the cleaning process has become very
important.
[0004] However, impurities that remain at an edge section, a side
section and a bottom section of the semiconductor substrate while
the unit processes are being carried out typically are not
completely removed through a general cleaning process. In order to
clean the edge, side and bottom sections of the semiconductor
substrate on which a metal wiring is formed, photoresist
composition is coated on the semiconductor substrate, and exposure
and development processes are carried out on the semiconductor
substrate except for the metal wiring section. Thereafter, the
semiconductor substrate is cleaned through various methods.
[0005] In a single-wafer type cleaning method, cleaning liquid is
supplied to the edge section of the semiconductor substrate while
rotating a vacuum chuck that grips the semiconductor substrate,
thereby removing the impurities sticking to the edge section of the
semiconductor substrate. In a batch type cleaning method, multiple
lots of semiconductor substrates are simultaneously cleaned in a
bath having the cleaning liquid therein.
[0006] However, the single-wafer type cleaning method may not
effectively remove the impurities sticking to the side and bottom
sections of the semiconductor substrate. In the batch type cleaning
method, because the impurities separated from the semiconductor
substrate float on the cleaning liquid or reside in the cleaning
liquid, the impurities may reattach to the semiconductor substrate.
Furthermore, the batch type cleaning method may not effectively
clean the edge and side sections of the semiconductor
substrate.
[0007] The impurities sticking to the surface of the semiconductor
substrate may ca use a process failure when performing a following
process, thereby lowering the yield and productivity of the
semiconductor device. In addition, because the photolithography
process is required for protecting the metal wiring during the
cleaning process, the manufacturing cost of the semiconductor
device is increased.
[0008] Various attempts have been made to solve the foregoing
problems. For example, Japanese Patent Publication No. 11-260778
(issued to Kuniyasu) discloses a single-wafer type cleaning device.
Cleaning liquid is supplied to a surface of a wafer from a cleaning
liquid nozzle. An ultrasonic wave is simultaneously provided by
means of an ultrasonic vibration plate, thereby effectively
removing the impurities from the wafer with improved cleaning of a
bottom of the wafer. However, Kuniyasu's cleaning device does not
selectively clean a specific portion of the wafer. U.S. Pat. No.
5,729,856 to Jang et al. discloses a cleaning device for cleaning
an edge section of a wafer. U.S. Pat. No. 6,114,254 to Rolfson
discloses a cleaning device in which cleaning liquid is supplied to
edge and bottom sections of a wafer. However, the cleaning devices
of the U.S. patents may cause a center portion of the wafer formed
with a metal wiring to be exposed to the cleaning liquid.
SUMMARY OF THE INVENTION
[0009] Embodiments of the present invention provide cleaning
apparatus and methods that can effectively remove impurities from
edge, side and bottom sections of a semiconductor substrate while
preventing cleaning liquid from penetrating into a center portion
of the semiconductor substrate.
[0010] According to method embodiments of the present invention, a
method for cleaning a semiconductor substrate includes rotating the
semiconductor substrate. A cleaning liquid is supplied to an edge
section of the semiconductor substrate for cleaning the edge
section and a side section of the semiconductor substrate. An
ultrasonic wave is applied to the cleaning liquid supplied to the
edge section.
[0011] According to further embodiments of the present invention,
an apparatus for cleaning a semiconductor substrate having an edge
section and a side section includes a chuck on which the
semiconductor substrate can be mounted for rotating the
semiconductor substrate. When the semiconductor substrate is
mounted on the chuck, an upper nozzle assembly is positioned above
the edge section of the semiconductor substrate to supply a
cleaning liquid to the edge section of the semiconductor substrate
for cleaning the edge section and the side section of the
semiconductor substrate. When the semiconductor substrate is
mounted on the chuck, an ultrasonic wave generator is positioned
above the edge section to apply ultrasonic waves to the cleaning
liquid supplied to the edge section.
[0012] The cleaning liquid supplied from the upper nozzle may flow
from the edge section to the side section of the semiconductor
substrate, and the ultrasonic waves may be applied to the cleaning
liquid supplied to the edge section. In this manner, the cleaning
effect with respect to the edge and side sections of the
semiconductor substrate can be improved.
[0013] In addition, first and second nitrogen gas streams may be
supplied from further respective nozzles to prevent the cleaning
liquid from moving into the center portion of the semiconductor
substrate. Accordingly, a pattern and a metal wiring formed on the
semiconductor substrate can be protected from the cleaning
liquid.
[0014] In addition, a further nozzle may be provided to supply a
second cleaning liquid to a bottom section of the semiconductor
substrate. The ultrasonic waves generated from the ultrasonic wave
generator may be applied to the second cleaning liquid supplied to
the bottom section by passing through the semiconductor substrate
to improve the cleaning effect with respect to the bottom
section.
[0015] Objects of the present invention will be appreciated by
those of ordinary skill in the art from a reading of the figures
and the detailed description of the preferred embodiments which
follow, such description being merely illustrative of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a flow chart representing methods for cleaning a
semiconductor substrate according to embodiments of the present
invention;
[0017] FIG. 2 is a schematic, sectional view of a cleaning
apparatus for performing methods as illustrated by the flow chart
of FIG. 1 according to embodiments of the present invention;
[0018] FIG. 3 is a detailed view of a clamp of the apparatus of
FIG. 2;
[0019] FIG. 4 is a detailed view of upper and lower nozzle
assemblies of the apparatus of FIG. 2;
[0020] FIG. 5 is a detailed view of the upper nozzle assembly of
FIG. 4;
[0021] FIG. 6 is a block diagram showing a control system for
controlling operations of the cleaning apparatus of FIG. 2; and
[0022] FIG. 7 is a fragmentary view showing flow directions of
first and second cleaning liquids of the apparatus of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. In the drawings, the
relative sizes of regions may be exaggerated for clarity. It will
be understood that when an element such as a layer, region or
substrate is referred to as being "on" another element, it can be
directly on the other element or intervening elements may also be
present. In contrast, when an element is referred to as being
"directly on" another element, there are no intervening elements
present.
[0024] With reference to FIG. 1, the flow chart thereof illustrates
methods in accordance with the present invention for cleaning a
semiconductor substrate. With reference to FIG. 2, a cleaning
apparatus 10 according to embodiments of the present invention is
shown therein. Various components and subsections of the cleaning
apparatus 10 are further illustrated in FIGS. 3-7, including a
control system 121 as shown in FIG. 6.
[0025] Referring to FIG. 1, according to method embodiments of the
invention, a semiconductor substrate 900 is loaded in a rotating
chuck by means of a conveying device, such as a robot, and the
rotating chuck is rotated at a proper speed (Step S100). Then, a
first cleaning liquid is supplied to an edge section 900a (see FIG.
4) of the semiconductor substrate 900 being rotated.
Simultaneously, first and second nitrogen gas streams are provided
to restrict, and preferably prevent, the first cleaning liquid from
moving toward a center portion 900c (see FIG. 4) of the
semiconductor substrate. At the same time, a second cleaning liquid
is supplied to a bottom section 900d (see FIG. 4) of the
semiconductor substrate (Step S200).
[0026] Thereafter, ultrasonic radiation or waves are applied to the
first cleaning liquid supplied onto the edge section 900a of the
semiconductor substrate. The ultrasonic waves are also applied to
the second cleaning liquid by passing through the semiconductor
substrate (Step S300). The first cleaning liquid flows from the
edge section 900a to the side section 900b of the semiconductor
substrate. The second cleaning liquid flows along the bottom
section 900d of the semiconductor substrate. The ultrasonic waves
can improve the cleaning efficiency of the first and second
cleaning liquids. The cleaning time and composition of the cleaning
liquid can be varied depending on the impurities to be removed.
When the cleaning process has been finished, the rotation of the
chuck is stopped and the semiconductor substrate is unloaded from
the chuck (Step S400).
[0027] The first cleaning liquid is supplied, preferably as a
liquid stream, from the center portion 900c of the semiconductor
substrate towards the edge section 900a of the semiconductor
substrate, preferably at an incident angle of 30 to 60 degrees,
such that the first cleaning liquid is prevented from moving or
being displaced to the center portion 900c. In addition, the first
and second nitrogen gas streams are respectively supplied to first
and second sections of the semiconductor substrate, which are
spaced apart from the edge section 900a in the direction of the
center portion 900c. The first nitrogen gas stream is preferably
supplied at an incident angle of 30 to 60 degrees in the same
direction as the supplying direction of the first cleaning liquid.
In addition, the second nitrogen gas stream is preferably supplied
at an incident angle of 15 to 30 degrees in the same direction as
the supplying direction of the first cleaning liquid. At this time,
the edge section 900a is spaced apart from the side section 900b of
the semiconductor substrate by about 5 mm or less, and the first
section 900e (see FIG. 5) is spaced apart from a first cleaning
liquid receiving portion, to which the first cleaning liquid is
supplied, by about 3 to 15 mm. The first section 900e may be the
same as the second section. However, the present invention is not
limited to the described ranges of the edge section 900a and the
first and second sections. Rather, such ranges can be varied
depending on sections of the semiconductor substrate to be
cleaned.
[0028] Preferably, the rotating speed of the semiconductor
substrate is between about 18 and 20 rpm, and the flow rate of the
first and second cleaning liquid is between about 1 and 5
liters/minute. In this case, the first and second cleaning liquids
supplied to the edge section and bottom section of the
semiconductor substrate can stably flow along the side and bottom
sections of the semiconductor substrate, respectively, without
moving or being displaced therefrom. However, in accordance with
the present invention, the rotating speed of the semiconductor
substrate and the flow rate of the cleaning liquid may be varied
depending on the conditions of the cleaning process.
[0029] Examples of the first and second cleaning liquids include
deionized water, a mixture of HF and deionized water, a mixture of
NH.sub.4OH, H.sub.2O.sub.2 and deionized water, a mixture of
NH.sub.4F, HF, and deionized water, a mixture of H.sub.3PO.sub.4
and deionized water, etc.
[0030] Generally, deionized water may be used for removing
impurities from the semiconductor substrate and for rinsing the
semiconductor substrate.
[0031] The mixture (DHF) of HF and deionized water may be used for
removing native oxide (SiO.sub.2) layer and metal ions formed on
the semiconductor substrate. The mixing ratio of HF to deionized
water is preferably between about 1:100 and 1:500. However, the
mixing ratio can be varied depending on the cleaning
conditions.
[0032] Generally, the mixture of NH.sub.4OH, H.sub.2O.sub.2 and
deionized water, referred to as SC1 (standard cleaning 1) solution,
may be used to remove an oxide layer formed on the semiconductor
substrate and organic matter attached to the semiconductor
substrate. The mixing ratio of NH.sub.4OH, H.sub.2O.sub.2 and
deionized water is preferably about 1:4:20 and about 1:4:100. The
mixing ratio can be varied depending on the conditions of the
cleaning process.
[0033] In addition, the mixture of NH.sub.4F, HF, and deionized
water, referred to as LAL solution, may be used to remove an oxide
layer formed on the semiconductor substrate, and the mixture of
H.sub.3PO.sub.4 and deionized water may be used to remove nitride
based impurities.
[0034] The cleaning efficiency is improved as the temperature of
the first and second cleaning liquids increases, and the
temperature can be properly adjusted. In addition, the various
cleaning liquids can be sequentially used depending on the kinds of
impurities to be removed.
[0035] Further aspects of methods according to the invention are
discussed below with reference to the cleaning apparatus 10.
[0036] Referring to FIG. 2, the cleaning apparatus 10 includes a
chamber 100 defining a space for performing the cleaning process. A
door 102 is provided at one side of the chamber 100 so as to allow
the semiconductor substrate 900 to be introduced into and withdrawn
from the chamber 100. A chuck 104 is provided in the chamber 100.
The chuck 104 grips and rotates the semiconductor substrate 900. A
cover 106 is provided at a peripheral portion of the chuck 104 in
order to prevent the cleaning liquid separated from the
semiconductor substrate 900 from dispersing in the chamber 100
while the cleaning process is being carried out. A first pneumatic
cylinder 108 is installed at a side of the cover 106 to drive an
upper nozzle assembly 200 for cleaning the edge and side sections
of the semiconductor substrate 900. Installed below the chamber 100
are a motor for rotating the chuck 104 and a second pneumatic
cylinder 112 for driving the cover 106 up and down. In addition, a
lower nozzle assembly 300 is positioned below the semiconductor
substrate 900 so as to clean a bottom section of the semiconductor
substrate 900.
[0037] The cover 106 has a cup shape and surrounds the chuck 104.
The first pneumatic cylinder 108 is installed at an outer wall of
the cover 106. A rod 108a of the first pneumatic cylinder 108
extends towards the chuck 104 by passing through the cover 106. An
ultrasonic wave generator 250 is connected to an end of the rod
108a of the first pneumatic cylinder 108. The rod 108a of the first
pneumatic cylinder 108 is driven in a radial direction relative to
the semiconductor substrate 900 so as to adjust the position of the
upper nozzle assembly 200 and ultrasonic wave generator 250. The
upper nozzle assembly 200 includes a plurality of nozzles and a
guide 260 through which the ultrasonic wave generator 250 is
installed. That is, the first pneumatic cylinder 108 simultaneously
drives the upper nozzle assembly 200 and the ultrasonic wave
generator 250, which is described in more detail below with
reference to FIG. 4. A drain tube 114 for draining the used
cleaning liquid is connected to a lower side of the cover 106. A
rotating shaft 116 connected to the motor 110 for rotating the
semiconductor substrate 900 is installed below the cover 106 by
passing through the center of the bottom of the cover 106.
[0038] A plurality of radially extending rods 118 is provided at an
upper portion of the rotating shaft 116. The rods 118 transfer the
driving force of the motor 110 while supporting the semiconductor
substrate 900. Each of the rods 118 has a clamp 120 connected
thereto for fixing the semiconductor substrate 900. Referring to
FIG. 3, each clamp 120 includes a clamp housing 120a connected to
the respective rod 118 and a clamp body 120b rotatably installed in
the clamp housing 120a. When the chuck 104 is at rest for loading
and unloading the semiconductor substrate 900, the clamp body 120b
rotates counterclockwise, to the position shown in dashed lines in
FIG. 3, due to the static weight balance thereof, thereby allowing
the semiconductor substrate 900 to be easily loaded or unloaded. On
the other hand, when the loaded chuck 104 and the semiconductor
substrate 900 are rotated, the clamp body 120 rotates clockwise, to
the position shown in solid lines in FIG. 3, due to a centrifugal
force, thereby gripping the semiconductor substrate 900.
[0039] Referring to FIG. 4, a bracket 208 for fixing the upper
nozzle assembly 200 is connected to the rod 108a of the first
pneumatic cylinder 108 installed at a side of the cover (see FIG.
2). A first nozzle 202 is connected to a lower portion of the
bracket 208 so as to supply the first cleaning liquid, preferably
as a liquid stream, to the edge section 900a of the semiconductor
substrate 900. A second nozzle 212 is arranged alongside the first
nozzle 202 so as to provide a first nitrogen gas stream for
primarily restricting, and preferably preventing, the first
cleaning liquid from moving into the center portion 900c of the
semiconductor substrate 900. In addition, a third nozzle 222 is
arranged alongside the second nozzle 212 so as to provide a second
nitrogen gas stream for secondarily restricting, and preferably
preventing, the first cleaning liquid from moving into the center
portion 900c of the semiconductor substrate 900. That is, the first
to third nozzles 202, 212 and 222 are sequentially positioned from
the edge section 900a towards the center portion 900c.
[0040] A first line 204 for guiding the first cleaning liquid is
connected to one end of the first nozzle 202. A first valve 206 is
installed in the first line 204 to control the flow rate of the
first cleaning liquid. A second line 214 for guiding the first
nitrogen gas is connected to one end of the second nozzle 212. A
second valve 216 is installed in the second line 214 to control the
flow rate of the first nitrogen gas. In addition, a third line 224
branched from the second line 214 is connected to one end of the
third nozzle 222 for guiding the second nitrogen gas. A third valve
226 is installed in the third line 224 so as to control the flow
rate of the second nitrogen gas.
[0041] In addition, the guide 260 is connected to a lower portion
of the bracket 208 to inhibit or prevent the first cleaning liquid,
which is supplied to the edge section 900a of the semiconductor
substrate 900 from the first nozzle 202, from being separated from
the edge section 900a of the semiconductor substrate 900 because of
the rotation of the semiconductor substrate 900. When the
semiconductor substrate 900 rotates at a relatively low speed, the
first cleaning liquid flows from the edge section 900a of the
semiconductor substrate 900 to the side section 900b of the
semiconductor substrate 900. However, when the semiconductor
substrate 900 rotates at a relatively high speed, the first
cleaning liquid is separated from the semiconductor substrate 900
without flowing along the side section 900b of the semiconductor
substrate 900. The first cleaning liquid separated from the
semiconductor substrate 900 cannot wash the side section 900b of
the semiconductor substrate 900. For this reason, the guide 260 is
provided to direct the first cleaning liquid separated from the
semiconductor substrate 900 towards the edge section 900a or the
side section 900b of the semiconductor substrate 900. Accordingly,
the edge section 900a or the side section 900b of the semiconductor
substrate 900 can be washed by the first cleaning liquid redirected
towards the edge section 900a or the side section 900b by the guide
260.
[0042] The ultrasonic wave generator 250 for applying ultrasonic
waves to the first cleaning liquid supplied to the edge section
900a of the semiconductor substrate 900 has a rod shape and extends
towards an upper portion of the edge section 900a of the
semiconductor substrate 900 by passing through the guide 260.
[0043] The lower nozzle assembly 300 is provided below the
semiconductor substrate 900 in order to wash the bottom section
900d of the semiconductor substrate 900. The lower nozzle assembly
300 includes a fourth nozzle supplying a second cleaning liquid,
preferably as a liquid stream, to the bottom section 900d of the
semiconductor substrate 900, a fourth line 304 connected to one end
of the fourth nozzle 302 to guide the second cleaning liquid into
the fourth nozzle 302, and a fourth valve 306 installed in the
fourth line 304 so as to control the flow rate of the second
cleaning liquid. The position of the lower nozzle assembly 300 can
be variously adjusted such that the bottom section 900d of the
semiconductor substrate 900 can be selectively washed.
[0044] The first pneumatic cylinder 108 can adjust the position of
the upper nozzle assembly 200, preferably in about 0.1 .mu.m
increments. Preferably, the distance between the guide of the upper
nozzle assembly 200 and the semiconductor substrate 900 is at least
about 1 cm. Preferably, the edge section 900a of the semiconductor
substrate 900 except for the center portion 900c of the
semiconductor substrate 900 formed with a pattern and a metal
wiring is no greater than about 5 mm from the side section 900b of
the semiconductor substrate 900. In addition, the location on the
semiconductor substrate 900 to which the first cleaning liquid is
supplied is adjusted by the first pneumatic cylinder 108. However,
the present invention is not limited to the above ranges. The range
of the edge section 900a can be varied depending on the size of the
semiconductor substrate 900 and distribution of impurities to be
removed.
[0045] The flow rate of the first and second cleaning liquids
supplied through the first and fourth nozzles 202 and 302 is about
1 to 5 liters/minute, respectively. In addition, the first cleaning
liquid supplied to the edge section 900a of the semiconductor
substrate 900 flows along the side section 900b of the
semiconductor substrate 900 by passing through between the
semiconductor substrate 900 and the ultrasonic wave generator 250.
The ultrasonic waves generated from the ultrasonic wave generator
250 improve the cleaning efficiency of the cleaning liquid. The
ultrasonic waves are also applied to the second cleaning liquid
supplied to the bottom section 900d of the semiconductor substrate
900 by passing through the semiconductor substrate 900.
Accordingly, the cleaning effect with respect to the bottom section
900d of the semiconductor substrate 900 is improved. The flow rate
of the first and second cleaning liquids can be varied. It is
preferred to adjust the flow rate of the first and second cleaning
liquids such that the first and second cleaning liquids
simultaneously make contact with the semiconductor substrate 900
and the ultrasonic wave generator 250. At this time, the spacing
between the semiconductor substrate 900 and the ultrasonic wave
generator 250 is preferably between about 1 and 3 mm.
[0046] The guide 260 is preferably made of Teflon.TM. (PTFE) resin,
which is resistant against the cleaning liquid and has a long
lifetime and corrosion resistance. In addition, the first and
fourth lines 204 and 304 for providing the first and second
cleaning liquids are preferably made of a Teflon.TM. tube having a
diameter of about 1/16 to 1/8 inch. The third line 224 used for
providing the second nitrogen gas is preferably made of a
Teflon.TM. tube having a diameter of about 1/16 inch.
[0047] Referring to FIG. 5, the spacing between the first and
second nozzles 202 and 212 is preferably between about 3 and 15 mm.
The above spacing can be varied depending on the flow rate of the
first cleaning liquid, the rotational speed of the semiconductor
substrate 900, and the type of the first cleaning liquid. The
spacing between the edge section 900a to which the first cleaning
liquid is supplied and a first section 900e to which the first
nitrogen gas is supplied is dependent on the spacing between the
first and second nozzles 202 and 212.
[0048] The first nozzle 202 is inclined from the center portion
900c to the edge section 900a of the semiconductor substrate 900 so
as to prevent the first cleaning liquid from moving into the center
portion 900c of the semiconductor substrate 900. The first nozzle
202 preferably has an incline angle A of between about 30 and 60
degrees with respect to the semiconductor substrate 900 (i.e.,
relative to the plane P-P defined by the substantially planar upper
surface of the semiconductor substrate 900). An incline angle B of
the second nozzle 212 is preferably identical to the incline angle
A of the first nozzle and an incline angle C of the third nozzle
222 is preferably from about 15 to 30 degrees with respect to the
semiconductor substrate plane P-P.
[0049] The guide 260, which directs the first cleaning liquid
separated from the semiconductor substrate 900 towards the edge
section 900a or the side section 900b when the semiconductor
substrate 900 rotates at a high speed, preferably has an incline
angle from about 40 to 50 degrees with respect to the semiconductor
substrate plane P-P.
[0050] Referring again to FIG. 2, the first line 204 supplying the
first cleaning liquid and the fourth line 304 supplying the second
cleaning liquid are connected to a selection valve 122 to which
various cleaning liquid supplying lines are connected. The cleaning
liquid supplying lines include a deionized water supplying line
124a, an HF solution supplying line 124b in which HF is diluted
with deionized water, an SC1 solution supplying line 124c and an
LAL solution supplying line 124d. Additionally, various kinds of
cleaning liquids can be supplied depending on the sorts of
impurities to be removed. Though the first and second cleaning
liquids are supplied from the same line in the described
embodiment, the first and second cleaning liquids can be supplied
from different lines, respectively, depending on the sorts of
impurities to be removed.
[0051] The cleaning process of the semiconductor substrate 900 is
preferably carried out in the following order. Firstly, the door
102 is opened and the semiconductor substrate 900 is loaded on the
chuck 104. At this time, the first and second pneumatic cylinders
108 and 112 are in a compression state. Because the first pneumatic
cylinder 108 is compressed, the upper nozzle assembly 200 and the
ultrasonic wave generator 250 are positioned adjacent to the chuck
104. In addition, because the second pneumatic cylinder 112 is
compressed, the cover 106, the first pneumatic cylinder 108, the
upper nozzle assembly 200 and the ultrasonic wave generator 250 are
moved to predetermined positions to allow the semiconductor
substrate 900 to move into the chuck 104.
[0052] Then, a robot (not shown) conveying the semiconductor
substrate 900 moves out of the chamber 100 and the door 102 is
closed. A lift pin may be used to load the semiconductor substrate
900 into the chuck 104 from the robot.
[0053] Thereafter, the second pneumatic cylinder 112 is expanded so
that the cover 106, the first pneumatic cylinder 108, the upper
nozzle assembly 200 and the ultrasonic wave generator 250 are
upwardly moved to the cleaning position. Then, the first pneumatic
cylinder 108 is expanded so that the upper nozzle assembly 200 and
the ultrasonic wave generator 250 are moved toward the edge section
900a of the semiconductor substrate 900.
[0054] Then, the motor 110 rotates at a predetermined speed, and
the first and second cleaning liquids are supplied to the
semiconductor substrate 900 through the first and fourth nozzles
202 and 302. In addition, the first and second nitrogen gases are
supplied through the second and third nozzles 212 and 222. While
the first and second cleaning liquids are being supplied, the
ultrasonic waves generated from the ultrasonic wave generator 250
are applied to the first and second cleaning liquids. Then, the
first cleaning liquid flows from the edge section 900a of the
semiconductor substrate 900 to the side section 900b of the
semiconductor substrate 900, and the second cleaning liquid flows
along the bottom section 900d of the semiconductor substrate 900
due to the centrifugal force caused by the rotation of the
semiconductor substrate 900.
[0055] When impurities have been removed from the edge section
900a, side section 900b, and bottom section 900d of the
semiconductor substrate 900, the motor 110 is stopped and the first
and second pneumatic cylinders 108 and 113 are sequentially
operated, so that the cover 106, the first pneumatic cylinder 108,
the upper nozzle assembly 200 and the ultrasonic wave generator 250
are moved to their initial positions. Then, the semiconductor
substrate 900 is lifted (e.g., by a lift pin) and conveyed to a
following process by means of the robot.
[0056] Referring to FIG. 6, the cleaning apparatus shown in FIG. 2
further includes a control system 121 as shown therein. The control
system 121 includes a control section 126 for controlling the
cleaning process. The control section 126 is connected to a power
supply 128, which provides power as required for operating the
cleaning apparatus. The control section 126 controls the rotational
force of the motor 110 for rotating the semiconductor substrate
900. The power supply 128 supplies the power to the motor 110 based
on a control signal from the control section 126.
[0057] The control section 126 controls the operation of the
selection valve 122. That is, when the type of the cleaning liquid
has been selected based on the impurities to be removed, the
control section 126 controls the operation of the selection valve
122 to supply the selected cleaning liquid to the semiconductor
substrate. The control section 126 can select only one cleaning
liquid or can sequentially select various kinds of cleaning liquids
depending on the sorts of impurities to be removed. In addition,
the power supply 128 supplies the power to the selection valve 122
for driving the selection valve 122 based on the control signal of
the control section 126. The selection valve 122 may be an
electromagnetic solenoid valve.
[0058] The first and second cleaning liquids passing through the
selection valve 122 are supplied to the edge section 900a and the
bottom section 900d of the semiconductor substrate 900 through the
first and fourth nozzles 202 and 302. At this time, the first and
fourth valves 206 and 306 control the flow rates of the first and
second cleaning liquids. The control section 126 generates a
control signal to control the operations of the first and fourth
valves 206 and 306. The power supply 128 supplies the power to the
first and fourth valves 306 based on the control signal from the
control section 126. The first and fourth valves 206 and 306 may be
electromagnetic solenoid valves.
[0059] The control section 126 controls the flow rate of the first
and second nitrogen gases which are supplied to the semiconductor
substrate 900 through the second nozzle 212 connected to the second
valve 216 and the third nozzle 222 connected to the third valve
226. In the same manner as in the first and fourth valves 216 and
226, the second and third valves 216 and 226 may be electromagnetic
solenoid valves.
[0060] The control section 126 generates a control signal for
controlling the operation of the first and second pneumatic
cylinders 108 and 112. The power supply 128 supplies the power to
first and second directional valves 132, which adjust the direction
and flow rate of pressurized air supplied to the first and second
pneumatic cylinders 108 and 112, based on the control signal
applied from the control section 126. The first and second
directional valves 130 and 132 adjust the direction and flow rate
of the pressurized air by means of electromagnetic solenoids.
[0061] The structure of the control system according to the present
invention can be varied depending on the conditions of the cleaning
apparatus. That is, the kinds of valves used for controlling the
flow rate of the first and second cleaning liquids, first and
second nitrogen gases, and the pressurized air can be varied. In
addition, a pressure control valve and a safety valve can be added
to the control system. It is also possible to use a hydraulic
cylinder instead of first and second pneumatic cylinders operated
by the pressurized air. In addition, the first and second pneumatic
cylinders can be replaced with, for example, a motor and lead
screw.
[0062] The flow direction of the first and second cleaning liquids
is illustrated in FIG. 7. Referring to FIG. 7, the first cleaning
liquid supplied to the edge section 900a of the semiconductor
substrate 900 through the first valve 202 is prevented from moving
into the center portion 900c by the first and second nitrogen gas
streams supplied from the second and third nozzles 212 and 222. In
addition, the first cleaning liquid moves towards the side section
900b while making contact with the ultrasonic wave generator 250
and the edge section 900a. Then, the first cleaning liquid moves
down along the side section 900b. The second cleaning liquid
supplied to the bottom section 900d of the semiconductor substrate
900 through the fourth valve 302 moves to the side section 900b
while making contact with the bottom section 900d. Then, the second
cleaning liquid moves down together with the first cleaning liquid.
At this time, the guide 260 guides the first and second cleaning
liquids.
[0063] The frequency of the ultrasonic wave generated from the
ultrasonic wave generator 250 is varied depending on the kinds of
impurities to be removed. Generally, an ultrasonic wave having a
frequency above 800 kHz is used. The ultrasonic waves are applied
to the first cleaning liquid and are also applied to the second
cleaning liquid by passing through the semiconductor substrate
900.
EXAMPLE
[0064] Table 1 shows test results of cleaning efficiency with
respect to the semiconductor substrate. The tests were carried out
with applying the ultrasonic waves to SC1 solution and without
applying the ultrasonic waves to general SC1 solution.
TABLE-US-00001 TABLE 1 Power 30 60 used sec sec SC1 (without
ultrasonic wave) 0 31.0% 35.0% SC1 (both surfaces of substrate) +
50 99.7% 99.3% ultrasonic wave (upper surface of 75 81.4% 92.5%
substrate 100 84.8% 93.1% 125 85.4% 95.8% Deionized water (upper
surface of 50 98.7% -- Front substrate) + SC1 (lower surface of
loading substrate) + ultrasonic wave 50 99.7% -- Bottom (upper
surface of substrate loading
[0065] In the above test, the semiconductor substrate was
intentionally contaminated with silicon nitride (SiN) gel, and the
silicon nitride gel was removed by using SC1 solution having a
temperature of about 65.degree. C. The frequency of the ultrasonic
wave was 830 kHz.
[0066] In the first test, the semiconductor substrate was loaded
such that a surface formed with the silicon nitride gel was
upwardly directed. When only the SC1 solution was used, 30% of the
silicon nitride gel was removed. On the other hand, when the
ultrasonic waves were applied to the SC1 solution, 81 to 99% of
silicon nitride gel was removed.
[0067] In the second test, deionized water was supplied onto an
upper surface of the semiconductor substrate and the SC1 solution
was supplied to the lower surface of the semiconductor substrate.
In addition, the ultrasonic waves were applied to the upper surface
of the semiconductor substrate. When the semiconductor substrate
was loaded such that a surface formed with the silicon nitride gel
was upwardly directed, 98.7% of silicon nitride gel was removed. In
addition, when the semiconductor substrate was loaded such that a
surface formed with the silicon nitride gel was downwardly
directed, 99.7% of silicon nitride gel was removed.
[0068] It can be noted from the second test that, when the
ultrasonic waves are applied, the cleaning efficiency is highly
improved even though only deionized water is used. In addition, it
can be noted that the ultrasonic waves applied to the upper surface
of the semiconductor substrate are also applied to the SC1 solution
supplied to the lower surface of the semiconductor substrate by
passing through the semiconductor substrate.
[0069] As described above, the cleaning apparatus according to the
present invention supplies first and second cleaning liquids to the
edge section 900a and bottom section 900d of the semiconductor
substrate being rotated and applies the ultrasonic waves to the
first cleaning liquid supplied to the edge section of the
semiconductor substrate. Accordingly, the impurities can be
effectively removed from the edge, side and bottom sections of the
semiconductor substrate.
[0070] In addition, the first and second nitrogen gas streams are
supplied to a predetermined portion of the edge section, to which
the first cleaning liquid is supplied, so the first cleaning liquid
can be prevented from moving into the center portion of the
semiconductor substrate.
[0071] Furthermore, the first cleaning liquid separated from the
semiconductor substrate caused by the rotation of the semiconductor
substrate is moved toward the edge section or side section of the
semiconductor substrate by means of the guide. Accordingly, the
cleaning efficiency can be improved at the edge and side sections
of the semiconductor substrate.
[0072] By effectively removing the impurities sticking to the edge,
side and bottom sections of the semiconductor substrate, it may not
be necessary to perform a photolithography process for cleaning a
specific portion of the semiconductor substrate. Therefore, the
manufacturing cost of the semiconductor device can be reduced and
the productivity of the semiconductor device can be improved.
[0073] The foregoing is illustrative of the present invention and
is not to be construed as limiting thereof. Although a few
exemplary embodiments of this invention have been described, those
skilled in the art will readily appreciate that many modifications
are possible in the exemplary embodiments without materially
departing from the novel teachings and advantages of this
invention. Accordingly, all such modifications are intended to be
included within the scope of this invention. Therefore, it is to be
understood that the foregoing is illustrative of the present
invention and is not to be construed as limited to the specific
embodiments disclosed, and that modifications to the disclosed
embodiments, as well as other embodiments, are intended to be
included within the scope of the invention.
* * * * *