U.S. patent application number 10/378211 was filed with the patent office on 2004-09-09 for fire polished showerhead electrode.
Invention is credited to Beach, Bradley.
Application Number | 20040173313 10/378211 |
Document ID | / |
Family ID | 32926428 |
Filed Date | 2004-09-09 |
United States Patent
Application |
20040173313 |
Kind Code |
A1 |
Beach, Bradley |
September 9, 2004 |
Fire polished showerhead electrode
Abstract
A method for processing a quartz showerhead-type electrode
having a first surface, a second surface, and a plurality of
passages extending through the electrode, from the first surface to
the second surface, each passage defined by a sidewall, which
comprises fire polishing the sidewalls. Additionally, the sidewalls
have a central portion and opposing transition areas adjacent to
the first and second surfaces, and the method comprises fire
polishing the transition areas. Further, the electrode may be
textured after fire polishing.
Inventors: |
Beach, Bradley; (Belmar,
NJ) |
Correspondence
Address: |
Thomas K. Stine, Esq.
WALLENSTEIN & WAGNER, LTD
53rd Floor
311 South Wacker Drive
Chicago
IL
60606-6630
US
|
Family ID: |
32926428 |
Appl. No.: |
10/378211 |
Filed: |
March 3, 2003 |
Current U.S.
Class: |
156/345.33 ;
156/345.47 |
Current CPC
Class: |
H01J 37/32532 20130101;
Y02P 40/57 20151101; H01J 37/3244 20130101; C03B 29/02 20130101;
C03C 23/007 20130101 |
Class at
Publication: |
156/345.33 ;
156/345.47 |
International
Class: |
C23F 001/00 |
Claims
I claim:
1. A method for processing a quartz showerhead-type electrode
comprising the steps of: providing a quartz plate having a first
surface, a second surface, and a passage extending through the
electrode, from the first surface to the second surface, the
passage defined by a sidewall; and fire polishing the sidewall.
2. The method of claim 1, further comprising the step of abrasively
texturing one of the surfaces of the electrode.
3. The method of claim 1, further comprising the steps of: filling
the passage with wax; and abrasively texturing one of the surfaces
of the electrode.
4. The method of claim 1, wherein the quartz plate is provided with
a plurality of passages extending through the electrode, from the
first surface to the second surface, each passage defined by a
sidewall, further comprising fire polishing the sidewalls.
5. The method of claim 4, further comprising the step of abrasively
texturing one of the surfaces of the electrode.
6. The method of claim 4, further comprising the steps of: filling
the passages with wax; and abrasively texturing one of the surfaces
of the electrode.
7. A method for manufacturing a quartz showerhead-type electrode,
comprising the steps of: providing a quartz plate having a first
surface and a second surface; creating a passage extending through
the plate, from the first surface to the second surface, the
passage defined by a sidewall; and fire polishing the sidewall.
8. The method of claim 7, further comprising the step of abrasively
texturing one of the surfaces of the plate.
9. The method of claim 7, further comprising the steps of: filling
the passage with wax; and abrasively texturing one of the surfaces
of the plate.
10. The method of claim 7, further comprising the steps of:
creating a plurality of passages extending through the plate, from
the first surface to the second surface, each passage defined by a
sidewall; and fire polishing the sidewalls.
11. The method of claim 10, further comprising the step of
abrasively texturing one of the surfaces of the plate.
12. The method of claim 10, further comprising the steps of:
filling the passages with wax; and abrasively texturing one of the
surfaces of the plate.
13. A quartz showerhead-type electrode, comprising: a quartz plate,
having a first surface and a second surface; and a passage
extending through the plate, from the first surface to the second
surface, the passage defined by a sidewall; wherein the sidewall is
fire polished.
14. The electrode of claim 13, wherein one of the surfaces of the
electrode is textured.
15. The electrode of claim 13, further comprising: a plurality of
passages extending through the plate, from the first surface to the
second surface, each passage defined by a sidewall; wherein the
sidewalls are fire polished.
16. The electrode of claim 15, wherein one of the surfaces of the
electrode is textured.
17. A method for processing a quartz showerhead-type electrode
comprising the steps of: providing a quartz plate having a first
surface, a second surface, and a passage extending through the
electrode, from the first surface to the second surface, the
passage defined by a sidewall having a central portion and opposing
transition areas adjacent to the first and second surfaces; and
fire polishing the transition areas.
18. The method of claim 17, further comprising the step of
abrasively texturing one of the surfaces of the electrode.
19. The method of claim 17, further comprising the steps of:
filling the passage with wax; and abrasively texturing one of the
surfaces of the electrode.
20. The method of claim 17, wherein the quartz plate is provided
with a plurality of passages extending through the electrode, from
the first surface to the second surface, each passage defined by a
sidewall having a central portion and opposing transition areas
adjacent to the first and second surfaces, further comprising fire
polishing the transition areas.
21. The method of claim 20, further comprising the step of
abrasively texturing one of the surfaces of the electrode.
22. The method of claim 20, further comprising the steps of:
filling the passages with wax; and abrasively texturing one of the
surfaces of the electrode.
23. A method for manufacturing a quartz showerhead-type electrode,
comprising the steps of: providing a quartz plate having a first
surface and a second surface; creating a passage extending through
the plate, from the first surface to the second surface, the
passage defined by a sidewall having a central portion and opposing
transition areas adjacent to the first and second surfaces; and
fire polishing the transition areas.
24. The method of claim 23, further comprising the step of
abrasively texturing one of the surfaces of the plate.
25. The method of claim 23, further comprising the steps of:
filling the passage with wax; and abrasively texturing one of the
surfaces of the plate.
26. The method of claim 23, further comprising the steps of:
creating a plurality of passages extending through the plate, from
the first surface to the second surface, each passage defined by a
sidewall having a central portion and opposing transition areas
adjacent to the first and second surfaces; and fire polishing the
transition areas.
27. The method of claim 26, further comprising the step of
abrasively texturing one of the surfaces of the plate.
28. The method of claim 26, further comprising the steps of:
filling the passages with wax; and abrasively texturing one of the
surfaces of the plate.
29. A quartz showerhead-type electrode, comprising: a quartz plate,
having a first surface and a second surface; and a passage
extending through the plate, from the first surface to the second
surface, the passage defined by a sidewall having a central portion
and opposing transition areas adjacent to the first and second
surfaces; wherein the transition areas are fire polished.
30. The electrode of claim 29, wherein the transition areas are
substantially smooth and curved.
31. The electrode of claim 29, wherein one of the surfaces of the
electrode is textured.
32. The electrode of claim 29, further comprising a plurality of
passages extending through the plate, from the first surface to the
second surface, each passage defined by a sidewall having a central
portion and opposing transition areas adjacent to the first and
second surfaces; wherein the transition areas are fire
polished.
33. The electrode of claim 32, wherein the transition areas are
substantially smooth and curved.
34. The electrode of claim 32, wherein one of the surfaces of the
electrode is textured.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a fire polished quartz
showerhead electrode.
BACKGROUND OF THE INVENTION
[0002] Plasmas are used for many processes to alter the surface of
a material, such as an integrated circuit chip wafer, in a
controlled manner. Typical applications include etching of
semiconductor wafers, ion implantation, ion milling, and removal of
material in a process known as reactive ion etching. Fabrication of
an integrated circuit usually begins with a thin, polished slice or
wafer of a high purity, single-crystal semiconductor material, such
as silicon or germanium, which is subjected to a sequence of
processing steps, such as deposition of materials on, or removing
materials from, the wafer to form structured layers of the
integrated circuit. Early etching techniques were based on chemical
etching agents. Early deposition processes included sputtering or
chemical vapor deposition techniques. More recently, etching and
deposition processes based on energetic plasma ions taking place in
a plasma reactor have been replacing the earlier techniques because
of environmental and health concerns, in addition to an improvement
in quality which results from the plasma process.
[0003] Plasma reactors typically include a chamber in which the
plasma is established, a source of gas which is ionized to form the
plasma, a source of energy to ionize the gas, a vacuum system to
reduce the pressure within the chamber to an appropriate level for
a particular process, and a means for allowing the gas to enter the
chamber in a controlled manner.
[0004] Generally, an item to be processed, which may typically be a
semiconductor wafer with appropriate masking, is placed within the
chamber and is electrically biased relative to the gas in order to
induce the charged species of the ionized gas to impinge on the
wafer, preferably substantially normal to the surface. In some
cases, chemically reactive gases are also used to enhance the rate
of etching in a process called reactive ion etching.
[0005] In a typical plasma etching system, the chamber has an upper
electrode which serves as an anode, and a lower electrode which
serves as a cathode. The item to be processed is generally mounted
on the cathode. In such a system, the cathode is biased negatively
with respect to the anode and the chamber walls, and thereby
establishes an electric field between the cathode and the
surrounding region. The electric field gradient established by the
negatively biased cathode is sufficiently strong to dissociate the
particular gas used in the chamber, at the operating pressure, to
form a plasma. The dissociated gas results in charged particles in
the form of electrons and positively charged ions, each of which
are accelerated by the electric field. The surface of the item to
be processed is etched by the positive ions that are accelerated
towards the negatively charged cathode by the electric field. It is
generally important in semiconductor processing that the ions
strike the wafer with a uniform flux density so that all parts of
the wafer are processed at the same rate, and that the ions follow
a path that is perpendicular to the surface of the wafer in order
to prevent defects associated with undesirable etching of the sides
of the semiconductor structures. It is also important that
extraneous particles which can cause defects are eliminated.
[0006] Generally the upper electrode, the anode, is provided with
gas passages in a distribution that encourages an even
distribution, and uniform flow, of plasma over the surface of the
item to be processed. Typically, the anode is comprised of a quartz
disk of uniform thickness, and is referred to as a showerhead
electrode in the art. These showerhead electrodes are often coated
with a photo-resist polymer before use in a plasma etching
system.
[0007] In manufacturing a showerhead electrode, the gas passages
are normally formed by drilling, boring, or some other mechanical
process. A disadvantage to these processing techniques is that they
leave rough edges, cracks, and other such surface defects in and
around the passages, which may allow tiny chips or particles of
material to separate from the surface during use, known as
"shedding." This shedding most often occurs at the edges of the
passages, where they meet the surface of the electrode. When
shedding occurs during plasma etching, particles of electrode
material can travel to the surface of the product being processed
and damage the surface, thereby ruining the product.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a method
for processing a quartz showerhead-type electrode. Accordingly, the
invention comprises the steps of providing a quartz plate having a
first surface, a second surface, and a passage extending through
the electrode, from the first surface to the second surface, the
passage defined by a sidewall, and fire polishing the sidewall.
[0009] It is contemplated that the invention may further comprise
the step of abrasively texturing one or more of the surfaces of the
electrode.
[0010] It is also contemplated that the invention may further
comprise the steps of filling the passage with wax and abrasively
texturing one or more surfaces of the electrode.
[0011] It is also contemplated that the quartz plate is provided
with a plurality of passages extending through the electrode, from
the first surface to the second surface, each passage defined by a
sidewall, and that the sidewalls are fire polished.
[0012] Additionally, the invention comprises the steps of providing
a quartz plate having a first surface, a second surface, and a
passage extending through the electrode, from the first surface to
the second surface, the passage defined by a sidewall having a
central portion and opposing transition areas adjacent to the first
and second surfaces, and fire polishing the transition areas.
[0013] It is also contemplated that the quartz plate is provided
with a plurality of passages extending through the electrode, from
the first surface to the second surface, each passage defined by a
sidewall having a central portion and opposing transition areas
adjacent to the first and second surfaces, and that the transition
areas are fire polished.
[0014] It is another object of the present invention to provide a
method for manufacturing a quartz showerhead-type electrode.
Accordingly, the invention comprises the steps of providing a
quartz plate having a first surface and a second surface, creating
a passage extending through the plate, from the first surface to
the second surface, the passage defined by a sidewall, and fire
polishing the sidewall.
[0015] It is contemplated that the invention may further comprise
creating a plurality of passages extending through the plate, from
the first surface to the second surface, each passage defined by a
sidewall, and fire polishing the sidewalls.
[0016] Additionally, the invention comprises the steps of providing
a quartz plate having a first surface and a second surface,
creating a passage extending through the plate, from the first
surface to the second surface, the passage defined by a sidewall
having a central portion and opposing transition areas adjacent to
the first and second surfaces, and fire polishing the transition
areas.
[0017] It is contemplated that the invention may further comprise
the steps of creating a plurality of passages extending through the
plate, from the first surface to the second surface, each passage
defined by a sidewall having a central portion and opposing
transition areas adjacent to the first and second surfaces, and
fire polishing the transition areas.
[0018] It is another object of the present invention to provide a
quartz showerhead-type electrode. Accordingly, the invention
comprises a quartz plate, having a first surface, a second surface,
and a passage extending through the plate, from the first surface
to the second surface, the passage defined by a sidewall, wherein
the sidewall is fire polished.
[0019] It is contemplated that one or more surfaces of the
electrode of the present invention may be textured.
[0020] It is also contemplated that the electrode of the present
invention may further comprise a plurality of passages extending
through the plate, from the first surface to the second surface,
each passage defined by a sidewall, wherein the sidewalls are fire
polished.
[0021] Additionally, the invention comprises a quartz plate, having
a first surface, a second surface, and a passage extending through
the plate, from the first surface to the second surface, the
passage defined by a sidewall having a central portion and opposing
transition areas adjacent to the first and second surfaces, wherein
the transition areas are fire polished.
[0022] It is contemplated that the electrode of the present
invention may further comprise a plurality of passages extending
through the plate, from the first surface to the second surface,
each passage defined by a sidewall having a central portion and
opposing transition areas adjacent to the first and second
surfaces, wherein the transition areas are fire polished.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The present invention is described in detail below with
reference to the following figures:
[0024] FIG. 1 is a top view of the showerhead electrode of the
present invention;
[0025] FIG. 2 is a cross-section view of the showerhead electrode
of FIG. 1 of the present invention;
[0026] FIG. 3 is a top view of a passage of the showerhead
electrode of the present invention before fire polishing, magnified
to show detail;
[0027] FIG. 4 is a cross-section view of the showerhead electrode
of FIG. 1 of the present invention after it has been coated with a
photo-resist polymer;
[0028] FIG. 5 is a cross-section view of the showerhead electrode
of FIG. 1 of the present invention, after the passages have been
filled with wax; and
[0029] FIG. 6 is a top view of a passage of the showerhead
electrode of the present invention after it has been fire polished
and textured.
DETAILED DESCRIPTION OF THE INVENTION
[0030] While this invention is susceptible of embodiment in many
different forms, there is shown in the drawings, and will herein be
described in detail, a preferred embodiment of the invention with
the understanding that the present disclosure is to be considered
as an exemplification of the principles of the invention and is not
intended to limit the broad aspect of the invention to the
embodiment illustrated.
[0031] A showerhead electrode 10 is illustrated in FIGS. 1 and 2.
The electrode 10 comprises a plate 20, with a first surface 30, a
second surface 32, and a plurality of passages 22. Each of the
passages 22 is defined by a generally cylindrical sidewall 28,
extending from the first surface 30 to the second surface 32. Each
sidewall 28 is made up of a central portion 25 and opposing
transition areas 24 at either end, which are adjacent to the first
30 and second surfaces 32. The dotted lines 27 in FIG. 2 illustrate
approximately the boundaries between the central portion 25 and the
transition areas 24. The passages 22 allow gas to flow through the
electrode 10. The plate 20 is generally disk-shaped. The first and
second surfaces 30, 32, respectively, are circular and are
substantially flat and parallel to each other. The passages 22 are
cylindrical in shape and are arranged in a pattern of concentric
circles, making them evenly dispersed on the electrode 10. The
passages 22 are typically 0.010 inches to 0.030 inches in
diameter.
[0032] The electrode 10 is made as follows. A disk-shaped quartz
plate 20 is provided, having a first surface 30 and a second
surface 32. A plurality of passages 22 are created, extending from
the first surface 30 to the second surface 32. The passages 22 may
be created ultrasonically or by using a water jet, a laser, or a
drill, such as with a diamond bit.
[0033] The electrode 10 is fire polished, most importantly at the
transition areas 24, to prevent shedding. Fire polishing prevents
shedding by eliminating chips or cracks in the electrode 10 that
may allow shedding to occur. These chips and cracks exist primarily
in the rough edges of the transition areas 24, which can be seen in
detail in FIG. 3. Fire polishing comprises heating a material until
its surface begins to soften and flow, and then allowing it to
cool, leaving a smooth surface. When the electrode 10 is fire
polished, the surface 30, 32 becomes smooth. Additionally, the
transition areas 24 become smooth and curved, as shown in FIG. 2.
This is believed to occur because surface tension in the flowing
quartz causes the material at the transition areas 24 to develop a
small radius, which remains after the material re-solidifies. The
smooth, curved surfaces of the fire polished transition areas 24
are not prone to shedding. When the sidewalls 28 of the passages 22
are fire polished, they become smooth as well.
[0034] A quartz electrode 10 may be fire polished by exposing it to
a hydrogen/oxygen flame until the surface reaches a temperature of
approximately 1700.degree. C., and then allowing it to cool.
Alternatively, fire polishing may be done locally around the
transition areas 24 by using a laser as the heat source. Fire
polishing may be utilized as a step in manufacturing a new
electrode or as a method of repairing a previously-used electrode,
and the present invention encompasses both. Suitable fire polishing
of quartz electrodes may be performed by Technical Glass Products,
Inc. of Painesville Twp., Ohio.
[0035] After the electrode 10 has been fire polished, the surfaces
30, 32 are textured. Texturing the surfaces 30, 32 of the electrode
10 is done by sand blasting or grit blasting with 320 grit aluminum
oxide (Al.sub.2O.sub.3) at low pressure. The rough surface created
by texturing improves adherence of a photo-resist polymer coating
34, which may later be applied to the surfaces 30, 32 of the
electrode 10, as shown in FIG. 4. Alternatively, as seen in FIG. 5,
the passages 22 may be filled with wax 26 before texturing, which
acts to protect the sidewalls 28 and/or the transition areas 24
from damage during the texturing process. After texturing is
complete, the wax 26 is removed by applying heat to melt the wax 26
away or by using a solvent to dissolve the wax 26.
[0036] The electrode 10 is annealed after fire polishing. Annealing
relieves residual stresses within the electrode material that may
be created by fire polishing. A quartz showerhead electrode 10 is
annealed by heating the electrode 10 to approximately 1140.degree.
C., holding at that temperature for approximately 3 hours, and
allowing the electrode 10 to cool in the oven overnight, rather
than removing it to cool. Suitable annealing of quartz electrodes
may also be performed by Technical Glass Products, Inc.
[0037] After the electrode 10 has been manufactured, fire polished,
annealed, and textured, the product is a quartz showerhead
electrode 10, as illustrated in FIGS. 1 and 2, having a textured
surface and smooth, curved transition areas 24. The textured
surface and smooth, curved transition areas 24 of such an electrode
may be seen in detail in FIG. 6.
[0038] While specific embodiments of the invention have been
illustrated and described herein, numerous modifications come to
mind without significantly departing from the spirit of the
invention and the scope of protection is only limited by the scope
of the accompanying Claims.
* * * * *