U.S. patent application number 13/445354 was filed with the patent office on 2012-08-02 for plasma, uv and ion/neutral assisted ald or cvd in a batch tool.
This patent application is currently assigned to APPLIED MATERIALS, INC.. Invention is credited to MAITREYEE MAHAJANI, Brendan McDougall, Joseph Yudovsky.
Application Number | 20120192792 13/445354 |
Document ID | / |
Family ID | 38661490 |
Filed Date | 2012-08-02 |
United States Patent
Application |
20120192792 |
Kind Code |
A1 |
MAHAJANI; MAITREYEE ; et
al. |
August 2, 2012 |
PLASMA, UV AND ION/NEUTRAL ASSISTED ALD OR CVD IN A BATCH TOOL
Abstract
CVD and ALD methods of using a batch processing chamber to
process substrates are described. A batch processing chamber
includes a chamber housing, a substrate boat for containing a batch
of substrates in a process region, and an excitation assembly for
exciting species of a processing gas. The excitation assembly is
positioned within the chamber housing and may include plasma, UV,
or ion assistance.
Inventors: |
MAHAJANI; MAITREYEE;
(Saratoga, CA) ; Yudovsky; Joseph; (Campbell,
CA) ; McDougall; Brendan; (Livermore, CA) |
Assignee: |
APPLIED MATERIALS, INC.
Santa Clara
CA
|
Family ID: |
38661490 |
Appl. No.: |
13/445354 |
Filed: |
April 12, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12883889 |
Sep 16, 2010 |
8168269 |
|
|
13445354 |
|
|
|
|
11381970 |
May 5, 2006 |
7798096 |
|
|
12883889 |
|
|
|
|
Current U.S.
Class: |
118/723R ;
118/728 |
Current CPC
Class: |
C23C 16/4583 20130101;
C23C 16/45508 20130101; C23C 16/45574 20130101; C23C 16/509
20130101; H01J 37/32009 20130101; C23C 16/46 20130101 |
Class at
Publication: |
118/723.R ;
118/728 |
International
Class: |
C23C 16/458 20060101
C23C016/458; C23C 16/50 20060101 C23C016/50 |
Claims
1. An apparatus, comprising: a chamber; a substrate support
disposed in the chamber and facing a top of the chamber; and a gas
injector disposed inside the chamber along a side of the chamber,
the gas injector comprising a gas flow channel that is a source of
energy for exciting a gas in the gas flow channel.
2. The apparatus of claim 1, wherein the gas flow channel is formed
in an electrode.
3. The apparatus of claim 1, wherein the gas injector is an
electrode.
4. The apparatus of claim 1, wherein the gas injector comprises a
UV source.
5. The apparatus of claim 2, wherein the injector is oriented in a
direction perpendicular to a plane defined by the substrate
support.
6. The apparatus of claim 3, wherein the gas injector is vertically
oriented.
7. The apparatus of claim 6, wherein the gas injector comprises
vertical openings.
8. An apparatus, comprising: a chamber; a substrate support
disposed in the chamber and facing a top of the chamber; a gas
injector disposed inside the chamber along a side of the chamber,
the gas injector comprising a gas flow channel formed in an
electrode; and an exhaust assembly that comprises an electrode.
9. The apparatus of claim 8, wherein each of the gas injector and
the exhaust assembly is oriented in a direction perpendicular to a
plane defined by the substrate support.
10. The apparatus of claim 8, wherein the exhaust assembly
comprises a plurality of electrodes.
11. The apparatus of claim 8, further comprising a power supply
coupled to the gas injector and the exhaust assembly.
12. The apparatus of claim 8, wherein the substrate support is
between the gas injector and the exhaust assembly.
13. The apparatus of claim 8, wherein the gas injector comprises a
plurality of vertical openings.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S. patent
application Ser. No. 12/883,889, filed Sep. 16, 2010, which is a
divisional of co-pending U.S. patent application Ser. No.
11/381,970, filed May 5, 2006, now U.S. Pat. No. 7,798,096, both of
which are herein incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the invention generally relate to an
apparatus and a method used during a batch deposition process, and
more specifically, embodiments relate to a batch processing chamber
and a batch processing method for depositing a material using a
processing gas having excited species.
[0004] 2. Description of the Related Art
[0005] A substrate fabrication process is often evaluated by two
related and important factors, which are device yield and the cost
of ownership (COO). The COO, while affected by a number of factors,
is greatly affected by the number of substrates processed per time,
i.e., the throughput of the fabrication process, and cost of
processing materials. Batch processing has been found to be
promising in the attempt to increase throughput. However, providing
processing conditions uniformly over an increased number of
substrates is a challenging task.
[0006] In addition, plasma assisted ALD or CVD processes, UV
assisted (photo-assisted) ALD or CVD processes, and ALD or CVD
processes having assistance directly by ions provided to a
processing area have been shown to be beneficial to some deposition
processes. For example, UV and plasma assisted processes have been
demonstrated to provide good film quality for high-k dielectrics
which are increasingly needed as device scale approaches sub 65 nm
applications. Plasma assisted ALD or CVD have also been
demonstrated to reduce thermal budget and process time requirements
as compared to similar thermally assisted processes.
[0007] Providing uniform process conditions over an increased
number of substrates is even more challenging if additional
assisting treatments are added to the processes as described above
for plasma assisted ALD or CVD processes, UV assisted
(photo-assisted) ALD or CVD processes, and ALD or CVD processes
having assistance directly by ions provided to a processing
area.
[0008] Plasma assisted ALD processes have used remote plasma
generation to attempt exposing substrates to uniform plasma
conditions within a batch chamber. The plasma is introduced through
a delivery system such as the gas delivery system of the batch
tool. However, this process may suffer from the relaxation of the
plasma prior to entering the process region.
[0009] Therefore, there is a need for an apparatus and a method for
uniformly and effectively depositing materials during ALD or CVD
processes in a batch tool with plasma assistance, UV assistance, or
ion assistance.
SUMMARY OF THE INVENTION
[0010] The invention generally provides a batch processing
apparatus in which a plurality of substrates is processed in
parallel. The apparatus includes an assembly for exciting species
of the one or more processing gases used for processing the
substrates by a plasma assistance, a UV assistance and/or an ion
assistance. Embodiments of the invention generally provide methods
of the assisted processes and apparatuses, in which the assisted
processes may be conducted for providing uniformly deposited
material.
[0011] According to one embodiment, a batch processing chamber is
provided which includes a chamber housing of the batch chamber, a
substrate boat for containing a batch of substrates in a process
region, and an excitation assembly for exciting species of a
processing gas. The excitation assembly is positioned within the
chamber housing.
[0012] According to another embodiment, a method for batch
processing of substrates is provided which includes processing a
batch of substrates vertically stacked in a substrate boat
positioned within a chamber, injecting processing gases into a
process region within the chamber, and assisting the processing by
exciting species of the processing gas within the chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] So that the manner in which the above recited features of
the invention can be understood in detail, a more particular
description of the invention, briefly summarized above, may be had
by reference to embodiments, some of which are illustrated in the
appended drawings. It is to be noted, however, that the appended
drawings illustrate only typical embodiments of this invention and
are therefore not to be considered limiting of its scope, for the
invention may admit to other equally effective embodiments.
[0014] FIG. 1 illustrates a sectional side view of an exemplary
batch processing chamber of the invention including an assembly for
exciting species of the processing gases.
[0015] FIG. 2 illustrates a sectional top view of a further
embodiment of a batch processing chamber of the invention including
an assembly for exciting species of the processing gases.
[0016] FIG. 3 illustrates a sectional side view of an embodiment of
a batch processing chamber of the invention including an assembly
for exciting species of the processing gases within a process
region.
[0017] FIG. 4 illustrates a sectional side view of another
embodiment of a batch processing chamber of the invention including
an assembly for exciting species of the processing gases within a
process region.
[0018] FIG. 5 illustrates a sectional side view of an exemplary
batch processing chamber of the invention including an assembly for
exciting species of the processing gases within an injector
assembly.
[0019] FIG. 6 illustrates a sectional side view of another
embodiment of an exemplary batch processing chamber of the
invention including an assembly for exciting species of the
processing gases within an injector assembly.
[0020] FIG. 7 illustrates a sectional side view of an even further
embodiment of an exemplary batch processing chamber of the
invention including an assembly for exciting species of the
processing gases within an injector assembly.
[0021] FIG. 8 illustrates a sectional side view of another
embodiment of an exemplary batch processing chamber of the
invention including an assembly for exciting species of the
processing gases within an injector assembly.
[0022] FIG. 9 illustrates a sectional side view of another
embodiment of an injector assembly for a batch processing chamber
of the invention including an assembly for exciting species of the
processing gases within an injector assembly.
DETAILED DESCRIPTION
[0023] The invention generally provides an apparatus and a method
for processing semiconductor substrates in a batch with assemblies
for assisting the processes by generated ions. In one embodiment of
the invention, a batch processing chamber with an excitation
assembly, which is positioned within the batch processing chamber
housing, is provided. An example of a batch processing chamber
which may be useful for one embodiment described herein is a
FLEXSTAR.RTM. system, available from Applied Materials, Inc.,
located in Santa Clara, Calif.
[0024] Generally, excited species of processing gases may be
generated to assist the ALD or CVD processes as described herein.
These species may be excited by plasma assistance, UV assistance
(photo assistance), ion assistance (e.g., ions generated by an ion
source), or combinations thereof. The species are excited in or in
the vicinity of the process region within the chamber housing to
avoid relaxation of the excited states before the ions reach the
process region of the batch processing chamber.
[0025] A "substrate" as referred to herein, includes, but is not
limited to, semiconductor wafers, semiconductor workpieces, and
other workpieces such as optical planks, memory disks and the like.
Embodiments of the invention may be applied to any generally flat
workpiece on which material is deposited by the methods described
herein.
[0026] "Vertical direction" and "horizontal direction" are to be
understood as indicating relative directions. Thus, the horizontal
direction is to be understood as substantially perpendicular to the
vertical direction and vice versa. Nevertheless, it is within the
scope of the invention that the described embodiments and aspects
may be rotated in its entirety such that the dimension referred to
as the vertical direction is oriented horizontally and, at the same
time, the dimension referred to as the horizontal direction is
oriented vertically.
[0027] A batch processing chamber for ALD or CVD processing useful
for embodiments described herein is described in commonly assigned
U.S. Ser. No. 11/249,555, entitled "Reaction Chamber with Opposing
Pockets for Gas Injection and Exhaust," filed Oct. 13, 2005, which
is incorporated herein by reference for providing further
description of a chamber, a heating system, a gas delivery system,
and an exhaust system.
[0028] FIG. 1 illustrates one embodiment of a batch processing
chamber having an inner chamber 101 (e.g., a quartz chamber), and
controlled inject and exhaust. Typically, the inject assembly 150
and the exhaust assembly 170 are temperature controlled to avoid
condensation of processing gases. FIG. 1 is a sectional side view
of a batch processing chamber 100. The batch processing chamber 100
generally contains an inner chamber 101 defining a process region
117 configured to accommodate a batch of substrates 121 stacked in
a substrate boat 120. The substrates are provided in the process
region to be processed by various deposition processes, such as an
ALD process or a CVD process. Generally, one or more heater blocks
(not shown) are arranged around the inner chamber 101 and are
configured to heat the substrates 121 provided in the process
region 117. In one embodiment, the inner chamber 101 may for
example be a quartz chamber. An outer chamber 113 is generally
disposed around the inner chamber 101. One or more thermal
insulators (not shown) may be provided between the outer chamber
113 and any heaters in order to keep the outer chamber cool.
[0029] An example of the heater blocks and the thermal insulators,
which may be used in the embodiment shown in FIG. 1, is shown in
the embodiment of FIG. 2. FIG. 2, shows one or more heater blocks
211, which are arranged around the inner chamber 201 and are
configured to heat the substrates provided in the process region.
An outer chamber 213 is generally disposed around the inner chamber
201. In one embodiment, the inner chamber 201 may, for example, be
a quartz chamber. In FIG. 2, thermal insulators 212 are be provided
between the outer chamber 213 and any heaters in order to keep the
outer chamber cool.
[0030] FIG. 1 shows the inner chamber 101, e.g., a quartz chamber,
generally containing a chamber body having an opening on the
bottom, an injector pocket formed on one side of the chamber body,
an exhaust pocket formed on the chamber body on an opposite side of
the injector pocket. The inner chamber 101 has a cylindrical shape
similar to that of the substrate boat 120. Thereby, the process
region 117 may be kept small. A reduced process region reduces the
amount of processing gas per batch and shortens residence time
during batch processing.
[0031] In one embodiment, the exhaust pocket 103 and the injector
pocket 104 may be welded in place with slots milled on the chamber
body of inner chamber 101. According to one embodiment, the
injector pocket and the exhaust pocket are flattened quartz tubing
with one end welded on the chamber body and one end open. The
injector pocket 104 and the exhaust pocket 103 are configured to
house injector assembly 150 and exhaust assembly 170. As described
in more detail in U.S. Ser. No. 11/249,555, entitled "Reaction
Chamber with Opposing Pockets for Gas Injection and Exhaust," filed
Oct. 13, 2005, incorporated by reference above, injector assembly
150 and exhaust assembly 170 may typically be temperature
controlled. Further, a support plate for supporting the inner
(quartz) chamber is further connected to a load lock positioned
below the bottom opening of inner chamber 101. The substrate boat
120 may be loaded and unloaded through the load lock. The substrate
boat 120 may be vertically translated between the process region
117 and the load lock via the opening at the bottom of the inner
chamber.
[0032] Examples of substrate boats that may be used in batch
processing chambers and during processes described herein are
further described in U.S. Ser. No. 11/216,969, entitled "Batch
Deposition Tool and Compressed Boat," filed Aug. 31, 2005, which is
incorporated herein by reference. Examples of methods and
apparatuses for loading and unloading substrate boats used in batch
processing is further described in U.S. Ser. No. 11/242,301,
entitled "Batch Wafer Handling System," filed Sep. 30, 2005, which
is incorporated herein by reference.
[0033] The heater blocks are generally wrapped around an outer
periphery of the inner chamber 101 except near the injector pocket
104 and the exhaust pocket 103. According to another embodiment
(not shown) the heater blocks 211 may also be wrapped around the
injector pocket 104 and/or the exhaust pocket 103. The substrates
121 are heated to an appropriate temperature by the heater blocks
through the inner chamber 101. The heaters are controlled to
achieve uniform heating of the substrates. In one embodiment,
points on the substrates 121 in a batch process attain the same set
point temperature plus or minus 1 degree Celsius. Configurations of
the batch processing chamber 100 improve temperature uniformity in
batch processing. For example, a cylindrical shape of the inner
chamber 101 results in edges of the substrates 121 evenly distanced
from the inner chamber. Also, the heaters may have multiple
controllable zones to adjust variations of temperature between
regions. The heater blocks may be made of resistive heaters
arranged in multiple vertical zones. In one example, the heater
blocks may be ceramic resistive heaters.
[0034] FIG. 1 illustrates that the injector pocket 104 may be
welded on a side of the chamber body defining an inject volume in
communication with the process region 117. The inject volume
typically extends along the entire height of the substrate boat 120
when the substrate boat is in a process position. The injector
assembly 150 disposed in the injector pocket may, thus, provide a
horizontal flow of processing gases to every substrate 121.
[0035] A recess is formed to hold walls of the injector pocket 104.
The injector assembly is thermally isolated, e.g., by seal 154.
Seal 154, which may be an o-ring or other suitable elements, also
provide a vacuum seal to control the pressure in the inner chamber
101. Thermal isolation of the injector assembly may be desired to
independently control the temperature of the injector.
[0036] Since the process region 117 and the injector volume are
usually kept in a vacuum state during process, an outer volume
between inner chamber 101 and chamber 113 may also be evacuated.
Keeping the outer volume under a reduced pressure may reduce
pressure generated stress on inner chamber 101. Additional vacuum
seals, such as o-rings, may be disposed between appropriate parts
of chamber 100, in order to control the pressure of the process
region 117, the vacuum/pressure stress applied to inner chamber
101, to control gas flow of inserted processing gases only towards
the process region. Further, one or more vacuum pumps may be
directly or via additional exhaust plenums (not shown) connected to
the inner chamber in order to control the pressure in the inner
chamber 101.
[0037] The temperature of various components in a batch processing
chamber may be independently controllable, especially when a
deposition process is to be performed in the batch processing
chamber. If the temperature of the injector assembly is too low,
the gas injected may condense and remain on the surface of the
injector assembly, which can generate particles and affect the
chamber process. If the temperature of the injector assembly is
high enough to evoke gas phase decomposition and/or surface
decomposition which may "clog" paths in the injector assembly. An
injector assembly of a batch processing chamber is heated to a
temperature lower than a decomposition temperature of a gas being
injected and higher than a condensation temperature of the gas. The
temperature of the injector assembly is generally different than
the processing temperature in the process region. In one example,
substrates may be heated up to about 600 degrees Celsius, while the
temperature of the injector assembly is about 80 degrees Celsius
during an atomic layer deposition process. Therefore, the
temperature of the injector assembly is controlled
independently.
[0038] FIG. 1 illustrates that the exhaust pocket 103 may be welded
on a side of the chamber body defining an exhaust volume in
communication with the process region 117. The exhaust volume
typically covers an entire height of the substrate boat 120 when
the substrate boat is in a process position such that the exhaust
assembly 150 disposed in the exhaust pocket may provide a
horizontal flow of processing gases to every substrate 121.
[0039] A recess is formed to hold walls of the exhaust pocket 103.
The exhaust assembly is thermally isolated, e.g., by seal 174. Seal
174, which may be an o-ring or other suitable elements, also
provide a vacuum seal to be able to control the pressure in the
inner chamber 101. Thermal isolation of the exhaust assembly may be
desired to independently control the temperature of the
exhaust.
[0040] Since the process region 117 and the exhaust volume are
usually kept in a vacuum state during process, an outer volume
between inner chamber 101 and chamber 113 may also be evacuated.
Keeping the outer volume vacuumed can reduce pressure generated
stress on the inner chamber 101. Additional vacuum seals, such as
o-rings, may be disposed between appropriate parts of chamber 100,
in order to control the pressure of the process region 117, the
vacuum/pressure stress applied to inner chamber 101, to control gas
flow of inserted processing gases only towards the process region.
Further, one or more vacuum pumps may be directly or via additional
exhaust plenums (not shown) connected to the inner chamber in order
to control the pressure in the inner chamber 101.
[0041] Temperature of various components in a batch processing
chamber may be controlled independently, especially when a
deposition process is to be performed in the batch processing
chamber. On the one hand, it is desirable to keep the temperature
in the exhaust assembly lower than the temperature in the
processing chamber such that the deposition reactions do not occur
in the exhaust assembly. On the other hand, it is desirable to heat
an exhaust assembly such that processing gases passing the exhaust
assembly do not condense and remain on the surface causing particle
contamination. If deposition of reaction byproducts on the exhaust
assembly does occur, then elevated temperatures on the exhaust
assembly may ensure that the deposition has good adhesion.
Therefore, the exhaust assembly may be heated independently from
the process region.
[0042] FIG. 1 illustrates that additionally a gas source 159 is
provided. The gas source 159 provides processing gas, like
precursor gases or deposition gases, treatment gases, carrier
gases, and purge gases via valve 158 and via inlet channel 156 into
the vertical channel 155 of the injector assembly. The vertical
channel 155 may also be denoted as plenum 155 or cavity 155. The
processing gas enters the process region 117 through openings 153
of the injector assembly. The plate and openings form a faceplate
152 to have a uniform distribution of the gas over the substrates
121 in the substrate boat 120.
[0043] Generally, carrier gases and purge gases, which may be used
as a processing gas, include N.sub.2, H.sub.2, Ar, He, combinations
thereof, and the like. During pretreatment steps H.sub.2, NH.sub.3,
B.sub.2H.sub.6, Si.sub.2H.sub.4, SiH.sub.6, H.sub.2O, HF, HCl,
O.sub.2, O.sub.3, H.sub.2O.sub.2 or other known gases may be used
as a processing gas. In one embodiment, deposition gases or
precursor gases may contain a hafnium precursor, a silicon
precursor or a combination thereof.
[0044] Exemplary hafnium precursors include hafnium compounds
containing ligands such as halides, alkylaminos, cyclopentadienyls,
alkyls, alkoxides, derivatives thereof or combinations thereof.
Hafnium precursors useful for depositing hafnium-containing
materials include HfCl.sub.4, (Et.sub.2N).sub.4Hf,
(Me.sub.2N).sub.4Hf, (MeEtN).sub.4Hf,
(.sup.tBuC.sub.5H.sub.4).sub.2HfCl.sub.2,
(C.sub.5H.sub.5).sub.2HfCl.sub.2,
(EtC.sub.5H.sub.4).sub.2HfCl.sub.2,
(Me.sub.5C.sub.5).sub.2HfCl.sub.2, (Me.sub.5C.sub.5)HfCl.sub.3,
(PrC.sub.5H.sub.4).sub.2HfCl.sub.2,
(.sup.iPrC.sub.5H.sub.4)HfCl.sub.3,
(.sup.tBuC.sub.5H.sub.4).sub.2HfMe.sub.2, (acac).sub.4Hf,
(hfac).sub.4Hf, (tfac).sub.4Hf, (thd).sub.4Hf, (NO.sub.3).sub.4Hf,
(.sup.tBuO).sub.4Hf, (.sup.iPrO).sub.4Hf, (EtO).sub.4Hf,
(MeO).sub.4Hf, or derivatives thereof. Exemplary silicon precursors
include SiH.sub.4, Si.sub.2H.sub.6, TDMAS, Tris-DMAS, TEOA, DCS,
Si.sub.2Cl.sub.6, BTBAS or derivatives thereof.
[0045] Alternative metal precursors used during vapor deposition
processes described herein include ZrCl.sub.4, Cp.sub.2Zr,
(Me.sub.2N).sub.4Zr, (Et.sub.2N).sub.4Zr, TaF.sub.5, TaCl.sub.5,
(.sup.tBuO).sub.6Ta, (Me.sub.2N).sub.5Ta, (Et.sub.2N).sub.5Ta,
(Me.sub.2N).sub.3Ta(N.sup.tBu), (Et.sub.2N).sub.3Ta(N.sup.tBu),
TiCl.sub.4, Til.sub.4, (.sup.iPrO).sub.4Ti, (Me.sub.2N).sub.4Ti,
(Et.sub.2N).sub.4Ti, AlCl.sub.3, Me.sub.3Al, Me.sub.2AlH,
(AMD).sub.3La, ((Me.sub.3Si)(.sup.tBu)N).sub.3La,
((Me.sub.3Si).sub.2N).sub.3La, (.sup.tBu.sub.2N).sub.3La,
(.sup.1Pr.sub.2N).sub.3La, derivatives thereof or combinations
thereof.
[0046] Even though FIG. 1 shows only one gas source, a person
skilled in the art will appreciate that a plurality of gas sources,
for example, one gas source for a first precursor, one gas source
for a second precursor, and one gas source for a carrier and purge
gas, may be coupled to the batch processing chamber 100. A gas flow
from the different gases may be switched on or off according to the
desired needs for a process. Thereby, 3- or 4-way valves may be
used to provide the different gases to the inlet channel 156.
Alternatively, two, three, or more inlet channels 156 may milled
horizontally across the inject assembly 150 and several vertical
channels 155 may be provided to insert different processing gases
in the process region.
[0047] As an example, inject assembly 250 has more than one inlet
channel, e.g., three inlet channels 256, as illustrated in FIG. 2.
In one embodiment, each of the three inlet channels 256 is
configured to supply the process region 117 with a processing gas
independently from each other. Each inlet channel 256 is connected
to a vertical channel 255. The vertical channels 255 may also be
denoted as cavities 255 or plenums 255. The vertical channels 255
are further connected to a plurality of evenly distributed
horizontal holes 253 and form a vertical faceplate on the center
portion of the inject assembly 250.
[0048] On the opposite end of inner chamber 101 from injector
assembly 150 an exhaust pocket 103 is provided in chamber 101.
Exhaust pocket receives exhaust assembly 170. An exhaust port 176
is formed horizontally across the exhaust assembly 170 near a
center portion. The exhaust port 176 opens to a vertical
compartment 175 formed in the center portion. The vertical
compartment 175 is further connected to a plurality of horizontal
slots 173 which are open to the process region 117. When the
process region 117 is being pumped out with vacuum pump 179 via
valve 178, processing gases first flow from the process region 117
to the vertical compartment 175 through the plurality of horizontal
slots 173. The processing gases then flows into an exhaust system
via the exhaust port 176. In one aspect, the horizontal slots 173
may vary in size depending on the distance between a specific
horizontal slot 173 and the exhaust port 176 to provide an even
draw across the substrate boat 120 from top to bottom.
[0049] Processing gases such as precursor gases, deposition gases,
treatment gases, purge or carrier gases, as described in more
detail above, are delivered to and from process region 117 by
injector assembly and exhaust assembly. A uniform gas flow across
each substrate 121 as well as a uniform gas flow across all
substrates vertically aligned in the substrate boat 120 is desired.
However, non-uniformity might be caused by irregularities in the
gas flow at the wafer edges. These irregularities may be prevented
by providing a diffuser 160 between the injector and the substrate
boat. The diffuser 160 may prevent the gas flow from direct impact
on the edge of the substrate. Diffuser 160 may have a V-shaped form
and may direct gas from the inlet tangentially along the
substrates.
[0050] The diffuser may be provided in various shapes and
positions. Generally, the diffuser may be provided between the
faceplate of the injector assembly and the substrate boat. Thereby,
the diffuser may be integrated in the substrate assembly and/or may
be positioned in the injector pocket of the inner chamber 101.
Various embodiments of diffusers which may be used in chambers and
methods of the application are described in more detail in U.S.
Patent Application, entitled: "Batch Processing Chamber with
Diffuser Plate and Injector Assembly", filed on an even dated
herewith (U.S. patent application Ser. No. 11/381,966), which is
incorporated herein by reference.
[0051] The gas flow with improved uniformity carries ionized
species of the processing gases, like precursor gases or carrier or
purge gases. The uniformity of the gas flow also improves the
uniformity of the ionized species, which are used to provide plasma
assisted, UV assisted, or ion assisted processes. Generally, the
process assistance by plasma, UV, ion generation can be
characterized as exciting the introduced gas or by ionizing the
introduced gases. The components providing the processing gas flow
to the process region 117 are configured to form a uniformly
deposited material across each substrate and across the substrates
in the substrate boat.
[0052] Plasma assisted batch processing has previously been
conducted with a remote plasma source. However, a remote plasma is
generated at larger distances with regard the process region. Thus,
the number of excited species within the plasma has already
considerably decreased as the plasma enters the process region. A
remote plasma source results in a relaxation of the plasma before
the plasma enters the process region.
[0053] The invention generally provides an apparatus and a method
for processing semiconductor substrates in a batch tool, in which,
e.g., the plasma for plasma assisted processing of substrates is
provided in the process region or close or adjacent to the process
region. Close or adjacent to the process region is to be understood
as having the plasma generation directly neighboring the process
region, or at least within the inner chamber, the injector pocket,
or the injector assembly.
[0054] An embodiment illustrated in FIG. 1 includes a power source
180 to generate a plasma, which is connected to the diffuser 160
and the faceplate 152 of the injector assembly 150. A plasma is
generated between the diffuser 160 and the faceplate 152 of the
injector assembly 150. The injector face is used as an anode and
the diffuser is used as a cathode to generate a plasma
therebetween. The power applied to generate the plasma can be
adapted to the desired application and may depend on the energy
necessary to ionize particular species in the processing gas
flowing into the process region. As a result, the plasma power may
vary depending on the process step presently conducted. For
example, for a plasma assisted ALD process, a different power maybe
applied during a gas flow of a first precursor, during purging or
pumping to remove the first precursor, during gas flow of a second
precursor and during purging or pumping to remove the second
precursor. Alternatively, some of the process steps may be
conducted at similar plasma power or without plasma assistance. For
example the purge steps may be conducted with the same power or
without power, whereas for the times when precursors are provided
to the process region, plasma power adapted for the first and
second precursor, respectively, is applied.
[0055] As already mentioned above, barrier seal 154 is disposed
between the inject pocket 104 and the inject assembly 150, and
barrier seal 174 is disposed between the exhaust pocket 103 and the
exhaust assembly 170. Thereby, processing chemicals are prevented
from entering any undesirable areas in the batch processing
chamber. Further, a vacuum seal for the quartz chamber may be
provided by seals 154, 174. Additionally, the seals, which may be
provided in the form of O-rings or the like, can electrically
insulate different components within the chamber from each other.
This is of increasing relevance as the power provided by power
supply 180 increases. Higher voltages applied to electrodes, e.g.,
the injector assembly, may require improved electrical insulation
of the injector assembly.
[0056] Within an embodiment shown in FIG. 1, the plasma may be
confined between the face of the injector assembly 150 and the
diffuser 160. Thereby, direct exposure of the substrate to a plasma
may be avoided. This might be desirable to prevent plasma damage to
the surfaces of the substrates. Accordingly, the diffuser shields
the substrates from the plasma.
[0057] In the embodiments described while making reference to FIG.
1, a plasma is generated in the horizontal direction. The plasma
extends along the vertical direction of the diffuser 160 and the
injector assembly 150. Thus, the horizontal plasma extends along
the vertical direction of the process region 117. The substrates
121 in the substrate boat 120 are exposed to the plasma along the
entire stack of substrates. The previously described uniform gas
flow provides a uniform distribution of ionized species of the
plasma across the wafers.
[0058] FIG. 2 illustrates a further embodiment of a batch
processing chamber having an inner chamber 201, and controlled
inject and exhaust. Typically, the injector assembly 250 and the
exhaust assembly 270 are temperature controlled to avoid
condensation of processing gases. FIG. 2 is a sectional top view of
a batch processing chamber 200. The batch processing chamber 200
generally contains an inner chamber 201 defining a process region
217 configured to accommodate a batch of substrates stacked in a
substrate boat 220. The substrates are provided in the process
region to be processed by various deposition processes, such as an
ALD process or a CVD process. Generally, one or more heater blocks
211, which are arranged around the inner chamber 201 and are
configured to heat the substrates provided in the process region.
An outer chamber 213 is generally disposed around the inner chamber
201. In FIG. 2, thermal insulators 212 are provided between the
outer chamber 213 and any heaters in order to keep the outer
chamber cool.
[0059] The inner chamber 201, e.g., a quartz chamber, generally
comprises a chamber body having an opening on the bottom, an
injector pocket formed on one side of the chamber body, an exhaust
pocket formed on the chamber body on an opposite side of the
injector pocket. The inner chamber 201 has a cylindrical shape
similar to that of the substrate boat 220. Thereby, the process
region 117 is kept relatively small. A reduced process region
reduces the amount of processing gas per batch and shortens
residence time during batch processing.
[0060] The exhaust pocket 203 and the injector pocket 204 may be
welded in place with slots milled on the chamber body. According to
an alternative embodiment, the exhaust pocket may be provided in
the form of vertically aligned tubes connecting the processing
region with the vertical compartment 275. According to one
embodiment, the injector pocket 204 and the exhaust pocket 203 are
flattened quartz tubing with one end welded on the chamber body and
one end open. The injector pocket 204 and the exhaust pocket 203
are configured to house injector assembly 250 and exhaust assembly
270. Injector assembly 250 and exhaust assembly 270 are typically
temperature controlled.
[0061] An embodiment illustrated in FIG. 2 includes a power source
280 to generate a plasma, which is connected to the diffuser 260
and the faceplate 252 of the injector assembly 250. A plasma is
generated between diffuser 260 and the face of the injector
assembly. The injector face is used as an anode and the diffuser is
used as a cathode to generate a plasma therebetween. The power
applied to generate the plasma can be adapted to the desired
application and may depend on the energy necessary to ionize
particular species in the processing gas flowing into the process
region. As a result, the plasma power may vary depending on the
process step presently conducted. For example, for a plasma
assisted ALD process, a different power maybe applied during a gas
flow of a first precursor, during purging or pumping to remove the
first precursor, during gas flow of a second precursor and during
purging or pumping to remove the second precursor.
[0062] Alternatively, some of the process steps may be conducted at
similar plasma power or without plasma assistance. For example, the
purge steps may be conducted with the same power or without power,
whereas plasma power adapted for the first and second precursor,
respectively, is applied during the injection of the respective
precursor gases.
[0063] In one embodiment, as shown in FIG. 2, the plasma may be
confined between the face of the injector assembly 250 and the
diffuser 260. Thereby, direct exposure of the substrate to a plasma
may be avoided. This might be desirable to prevent plasma damage to
the surfaces of the substrates. Accordingly, the diffuser shields
the substrates from the plasma.
[0064] In the embodiments described while making reference to FIG.
2, a plasma in horizontal direction is generated. The plasma
extends along the vertical direction of the diffuser and the
injector assembly. Thus, the horizontal plasma extends along the
vertical direction of the process region 217. The substrates in the
substrate boat 220 are exposed to the plasma along the entire stack
of substrates. The previously described uniform gas flow provides a
uniform distribution of ionized species of the plasma across the
wafers.
[0065] The batch processing chamber 200 includes an outer chamber
213, heater blocks 211 separated from the outer chamber by thermals
insulators 212. An inner chamber 201 including injector pocket 204
and exhaust pocket 203 or exhaust tubes surrounds substrate boat
220 located in the process region. The injector assembly 250 has
three inlet channels 256. Processing gas can be provided through
the channels to vertical channels 255 and enters the processing
location through openings 253 in the face of injector assembly 250.
The exhaust assembly 270 includes exhaust port 176, vertical
compartment 275 and horizontal slots 273.
[0066] Further, a v-shaped diffuser 260 is shown. Similarly to FIG.
1, a power source is coupled via the injector assembly to the
injector face and the diffuser to generate a plasma between the
injector face and the diffuser. FIG. 2 further illustrates a
conductive mesh 261 that further confines the plasma in the gap
between the diffuser and the injector face. The diffuser may
additionally be made permeable to confine the plasma and to improve
protection of the substrates from energetic particles. A permeable
diffuser may improve the uniformity of the gas flow across the
wafer. In the case of a permeable diffuser, the diffuser may be
provided in the form of a mesh. According to another embodiment
(not shown), mesh 261 and a permeable mesh diffuser 260 may be
provided as one unit to provide a cathode and to confine the plasma
between this cathode and the face of the injector assembly acting
as the anode. The confinement of plasma--if desired--may be
improved by minimizing or omitting a gap between the injector
assembly and the mesh or diffuser. Nevertheless, it is to be
understood that insulation may be provided in the event neighboring
elements form the anode and the cathode for plasma ignition and
maintenance.
[0067] The conductive and permeable mesh, the diffuser and the face
of the injector assembly extend along the direction in which the
substrates are stacked over each other in the substrate boat. In
the embodiments shown herein, this direction is the vertical
direction. The substrates are vertically stacked. As the plasma is
generated adjacent to the process region along the entire height of
the process region, on the one hand it is possible to provide
uniform plasma assisted process conditions in the process region.
On the other hand, since the plasma is generated adjacent the
process region hardly any relaxation of the excitation occurs until
the excited species get in contact with the substrates in the
process region.
[0068] FIG. 3 illustrates another embodiment of a batch processing
chamber 300 wherein plasma assisted ALD processes, plasma assisted
CVD processes or other plasma assisted processes may be conducted.
Within FIG. 3, elements that are the same in the embodiment of FIG.
1 are denoted with the same reference numbers. Alternatively, these
elements may be the same as in the embodiment shown in FIG. 2. A
repetition of the description of these elements and the related
purposes or usage is omitted for simplicity.
[0069] A power supply 380 is connected to the injector assembly 350
and the exhaust assembly 370 in order to generate a plasma between
the face of the injector and the opposing port of the exhaust.
[0070] The plasma is generated horizontally, that is parallel to
the surfaces of the substrates. The plasma extends along the
process region 117 of the inner chamber 101. The exhaust port may
be used as the cathode and the face of the injector assembly may be
used as the anode. In light of the increased distance between the
anode and the cathode, the voltage provided by the power supply
between the cathode and the anode has to be increased in order to
provide the same electrical field acting on the species of the
processing gas. As a result of the increased potential difference,
the charged components may need further electrical isolation from
surrounding components. In FIG. 3, this is indicated by an
increased gap between the injector assembly 350 and the injector
pocket of the inner chamber 101. Further, the gap of the exhaust
assembly 370 is increased. Seals 354 and 374 are also increased in
size to indicate the further electrical insulation. Even though, in
the case of a quartz chamber, an insulation of the face of the
injector assembly and the port of the exhaust assembly may partly
be provided by the non-conductive inner chamber, potentials
sufficiently high to create a plasma across the process region may
need additional insulation of components in the batch processing
chamber 300.
[0071] A further embodiment of a batch processing chamber 400
providing the option of conducting plasma assisted processes is
shown in FIG. 4. Within FIG. 4, elements that are the same in the
embodiments of FIG. 1 or other previous embodiments are denoted
with the same reference numbers. Alternatively, these elements may
be the same as in the embodiment shown in FIG. 2. A repetition of
the description of these elements and the related purposes or usage
is omitted for simplicity.
[0072] Within FIG. 4, as compared to chamber 300 of FIG. 3, an
electrode 470 is positioned in the inner chamber 101. The electrode
470 or the electrodes 470 may be provided in the form of a rod
disposed within the chamber cavity adjacent to the exhaust
assembly. Power supply 480 is connected to electrodes 470 and to
the injector assembly 350. The faceplate of the injector assembly
acts as an electrode. Within the embodiment shown in FIG. 4, a
plasma is generated horizontally, parallel to the substrate
surfaces of the substrates in the substrate boat. The generated
plasma extends across the process region and is exposed to the
substrates.
[0073] FIG. 4 shows three rods 470 as electrodes for plasma
generation. Alternatively, one or two vertical rods may also be
used as electrodes. Further, 4 or more rods may be used as
electrodes. The number and the arrangement of electrodes should be
adapted to provide a uniform plasma across the substrates and to
not disturb the uniformity of the gas flow of the processing
gases.
[0074] According to another embodiment (not shown), the rods may
also be positioned between the face of the injector assembly and
the substrate boat. Thereby, a plasma generation comparable to FIG.
1 may occur. The plasma is generated adjacent the substrate boat
within inner chamber 101, e.g., a quartz chamber. The plasma is
generated horizontally between the vertically extending face of the
injector assembly and the vertically extending set of rods.
Thereby, a direct exposure of the substrates to the plasma may be
reduced. However, the species of the processing gas, which have
been excited by the plasma, have little time to relax before
getting in contact with the substrate surface. As a further
alternative (not shown), electrodes may also be disposed at other
locations in the inner chamber 101.
[0075] FIGS. 5 and 6 illustrate further embodiments. Elements that
are the same in the embodiments of FIG. 1 or other previous
embodiments are denoted with the same reference numbers.
Alternatively, these elements may be the same as in the embodiment
shown in FIG. 2. A repetition of the description of these elements
and the related purposes or usage is omitted for simplicity.
[0076] For the embodiments of FIGS. 5 and 6, the plasma may be
generated in the injector assembly. In one embodiment, the plasma
may be generated in the vertical channel inside the injector
assembly. Also, the vertical channel may be denoted as plenum or
cavity.
[0077] FIG. 5 shows a batch processing chamber. The injector
assembly 550 includes vertical rods 553 insulated from each other
by insulator parts 559. Alternatively, the injector 550 may be
formed of an insulating material. A plasma power source 580 is
connected to the top rod 553 and the bottom rod 553. According to
one embodiment the top rod may be the cathode and the bottom rod
may be the cathode, whereas to another embodiment the top rod may
be the cathode whereas the bottom rod is the anode. The rods form
electrodes for generation of a plasma. The generated plasma is
confined in the vertically extending channels 555. The plasma is
generated vertically and the excited species of the processing gas
enter the process region horizontally through the openings in the
faceplate of the injector assembly.
[0078] According to an alternative embodiment, the faceplate of the
injector may be made of a conductive material to improve
confinement of the plasma within the vertical channel. The
embodiments described with respect to FIG. 5, may optionally
include a diffuser 160 as shown in FIG. 5 and described in more
detail with respect to FIGS. 1 and 2.
[0079] The embodiment shown in FIG. 6 also includes plasma
generating elements that provide a plasma in the vertical channel
of the injector assembly 650. The plasma is generated between the
walls of the vertical channel. One wall is the faceplate 152
including the openings 153. The other wall is electrode 652 is
provided in the body 651 of injector assembly 650. Electrode 652
forms the wall of the vertical channel opposing the faceplate 152.
The two electrodes connected to the power supply 680 are separated
by insulator element 659.
[0080] According to an alternative embodiment (not shown), the body
651 of the injector assembly may form one of the electrodes to
generate the plasma. The injector is formed of a conductive
material and no separate electrode 652 may be required. According
to this embodiment, the faceplate forming the opposing electrode
would also be connected to the body 651 by insulating elements 659.
The embodiments described with respect to FIG. 6, may optionally
include a diffuser 160 as shown in FIG. 5 and described in more
detail with respect to FIGS. 1 and 2.
[0081] Embodiments described herein with respect to FIGS. 1 to 6
illustrate batch processing chambers which may be used during
plasma assisted processes, e.g., ALD or CVD processes. Therein, the
plasma assistance provides ionized species of the processing gases
within the chamber and in or in the vicinity of the process region.
The presence of the plasma in the process region or in the vicinity
of the process region reduces relaxation of the excited states.
Since the plasma assistance provides ionized species of the
processing gases to the substrate surfaces, a plasma assisted
process can be considered one form of process based on excited
species of the processing gases.
[0082] In the following, another form of processes with assistance
of exciting species and respective embodiments of chambers will be
described. The processes, such as ALD processes or CVD processes,
are assisted by UV radiation. The UV light may be used to excite
and/or ionize species of the processing gases or, e.g., to maintain
the O.sub.3 concentration at a desired level. In light of the
excitation of species of processing gases, i.e., the electrons are
excited to higher excitation levels, UV assistance during batch
processing may also be considered one form of process that is
assisted by excited species.
[0083] On irradiation of the processing gases with UV light,
species of the processing gases are excited above ground state. The
excitation depends on the wavelength of the UV light. The
wavelength may be in the range of 126 nm to 400 nm. The excited
species assist ALD or CVD processes by initiating or enhancing
surface reactions of the precursors or reactance. The enhancement
may result in reduction of exposure time and, thus, increase
throughput. Additionally, film quality may improve because of more
complete reactions of the precursors.
[0084] For UV assisted film growth processes, the relaxation time
of the excited species may be in a range that by the time the
processing gas reaches the process region a remotely excited
processing gas has relaxed. For example, the O.sub.3 concentration
might decrease by the time it reaches the process region of the
deposition chamber if excited at a remote location. The O.sub.3
concentration may be maintained higher by activating O.sub.3 inside
the chamber.
[0085] An embodiment of a batch processing chamber 700 with UV
assistance is shown in FIG. 7. Within FIG. 7, elements that are the
same in the embodiments of FIG. 1 or other previous embodiments are
denoted with the same reference numbers. Alternatively, these
elements may be the same as in the embodiment shown in FIG. 2. A
repetition of the description of these elements and the related
purposes or usage is omitted for simplicity.
[0086] FIG. 7 illustrates an embodiment for irradiating UV light
vertically inside the vertical channel 755 of the injector assembly
750. A UV source 790 is provided at the upper end of the vertical
channel 755 and a UV source is provided at the lower end of the
vertical channel. Each source includes a lamp 792 and a window 793
facing the vertical channel. The window material can be chosen
depending from the UV wavelength. For example a quartz window may
be used for wavelength up to about 180 nm to 220 nm. Sapphire.,
magnesium fluoride or calcium fluoride windows may be used as
window 793 in the event of shorter wavelengths.
[0087] The UV light extends vertically along the vertical channel
755 and excites species of the processing gases in the injector
assembly before entering the process region. Within the embodiment
shown in FIG. 7, UV lamps like deuterium lamps or arc lamps filled
with Hg or Xe, may be used. The species of the processing gas
excited in the vertical channel are provided uniformly with the
uniform gas flow generated by the injector assembly, the exhaust
assembly and optionally be the diffuser, the gas flow being
described in more detail with respect to FIG. 1.
[0088] FIG. 8 shows another embodiment of batch processing chamber
800 with an injector assembly 850. The embodiment may be used for
UV assisted processes. Within FIG. 8, elements that are the same in
the embodiments of FIG. 1 or other previous embodiments are denoted
with the same reference numbers. Alternatively, these elements may
be the same as in the embodiment shown in FIG. 2. A repetition of
the description of these elements and the related purposes or usage
is omitted for simplicity.
[0089] FIG. 8 illustrates that the injector assembly shines UV
light through openings 153 of the faceplate horizontally and
parallel to substrate surfaces of substrates stacked in a substrate
boat. The UV light is generated in the vertical channel 855 by
striking a glow discharge with a noble gas in vertical channel 855.
The injector face 852 of the faceplate is configured as an anode.
The body 851 of the injector is electrically insulated by
insulators 859 from the anode. The vertical channel 855 functions
as a hollow cathode.
[0090] As described with previously with respect to FIG. 2, the
injector assembly may have a plurality of vertical channels. A
single one of the vertical channels or a plurality of vertical
channels may be used as a hollow cathode to provide UV light inside
the chamber.
[0091] In the event the electrical field in the injector may be too
small to strike a glow discharge, tips 854 can be mounted in the
injector. Thereby, the electrical field strength near the tips is
increased and the glow discharge can be ignited with smaller
voltages applied. According to another embodiment (not shown) the
tips 854 may be omitted if sufficient power is provided by power
source 880 to strike the glow discharge in the vertical
channel.
[0092] FIG. 9 shows another embodiment of an injector assembly. As
compared to the embodiment shown in FIG. 8, a separate conductive
element 950 is provided at the rear end of the vertical channel as
the cathode. The cathode 950 is provided with a plurality of small
cavities. These cavities are in the form of cylinders with a small
diameter in the range of 1 mm to 12 mm, are provided as an array of
additional hollow cathodes. Thereby, the hollow cathode effect
providing the UV light with a wavelength corresponding to the gas
in the vertical channel and/or the cathode material can be
multiplied. As a result, the photon density in the vertical channel
and in the process region wherein the substrates are processed can
be increased. Alignment between hollow cathodes and the faceplate
holes ensures that transmission into the process region is
optimized.
[0093] Tips 954 may be provided in the hollow cathodes. The tips
may be used to increase the electrical field strength due to the
small curvature of the tip and improve striking of a glow
discharged at lower voltage levels.
[0094] According to another embodiment (not shown) a glow discharge
may also be generated between the diffuser and the face of the
injector, that is one side of the faceplate. Thereby, the diffuser
is provided as the anode and the face of the injector is the
cathode.
[0095] For all embodiments where the glow discharge is contained in
a plenum of the injector for UV production, differential pumping
may used (not shown). In some instances, the process pressure at
the substrates may be lower than the pressure required by the glow
discharge used for UV production. In this case, gas used for glow
discharge may be diverted from the process chamber.
[0096] For all embodiments where the glow discharge is contained in
a plenum of the injector for UV production, an UV transparent
membrane may be fastened to the reactor side of the injector
faceplate (not shown.) In some instances, the process pressure at
the substrates may be higher than the pressure required by the glow
discharge used for UV production. In this case, gas from the
process is isolated from the gas used for glow discharge by a
barrier. Since the barrier is UV transparent, UV is transmitted to
the substrates. The barrier is thin to optimize UV transmission,
but thick enough to support a process pressure of up to about 10
Torr.
[0097] Generally, for the UV assisted batch processing chambers,
the wavelength of the UV radition, that is the photon energy, may
be selected based on the gases used in the hollow cathode. Typical
noble gases and their irradiated photon energy based on
recombination of the excited states are He (for example, 21.22 eV,
40.82 eV, 40.38 eV), Ne (for example, 16.85 eV, 16.67 eV, 26.9 eV)
or Ar (for example, 11.83 eV, 11.63 eV, 13.48 eV, 13.30 eV). Broad
spectrum UV from deuterium lamps, or other UV sources (for example
a mercury lamp), as well as softer UV radiation is also
applicable.
[0098] Further, for UV assisted batch processing chambers, a
susceptor for carrying the substrates formed of silicon carbide
(SiC) may be adapted to reflect the UV light. The susceptor profile
and the roughness may be adapted to reflectively focus the UV light
on the substrate surfaces. Thereby, a location of excitation of
processing gas species by UV radiation may be even closer to the
substrate surfaces. The cylindrical geometry of the inner chamber
101 favors glancing angles for which UV reflectivity is enhanced
relative to normal incidence. With a glow discharge in the injector
vertical channel, UV assisting may be provided during any process
step having appropriate conditions for the glow discharge. As
mentioned above, conditions in the plenum of the injector and the
processing region may vary if a gas diversion, a barrier or other
measures are provided. Thereby, conditions appropriate for glow
discharge may be provided in the parts of the chamber. Appropriate
process conditions may include the injection of a gas desired for
the glow discharge. For 11.63 eV and 11.83 eV photons from Ar, an
optimal pressure of the glow discharge is 0.45 Torr, and the
reflectivity for SiC is 0.4 at normal incidence and at .pi./4
incidence.
[0099] For CVD processes that require UV assistance, the expected
duty cycle is continuous. For ALD processes, there are several
instances for which UV assistance may be required for film
properties and/or for throughput. UV assistance may be required for
one or all precursor exposures where the photon energy may be
required to start the reaction between precursor molecule and
surface binding site. UV assistance may be required during the
cycle-purging steps at the end of an ALD cycle to complete the
surface reaction such that incorporation of reaction byproducts is
minimized.
[0100] In the following, further embodiments will be described
while making reference to FIGS. 8 and 9. As described above, UV
assisted processes can be provided with a vertically extending
anode and a vertically extending hollow cathode, wherein the anode
and the cathode is arranged such that the anode is closer to the
substrate boat holding the wafer stack.
[0101] The embodiments described above with respect to the plasma
assisted processes and the hollow cathode effect may also be
utilized for ion assisted ALD or CVD batch processing chambers.
Therefore, according to one embodiment, a diffuser would be the
cathode and the injector face would be the anode. According to
another embodiment, the injector face side of the vertical channel
(faceplate side of the vertical channel) would be the cathode and
the opposing side of the injector located towards the body of the
injector assembly would be the anode. Generally, the power supply
is connected to the respective components of the previous
embodiments with a polarization, such that ions are provided to the
processing region. In light of the ionization of species of
processing gases, ion generating assistance during batch processing
may also be considered one form of process assisted by excited
species. Further, the diffuser may be modified to provide a hollow
cathode effect.
[0102] Ions generated in the glow discharge are then accelerated
towards the process region. Ions and neutrals may pass the cathode
through openings provided therein. Thus, the ions and neutrals
enter the process region and can assisted processes by the energy
or the momentum of the ions. The kinetic energy of the ions and
neutrals may be about 600 eV. Optionally retarding grids may be
used to reduce the ion energy. A retarding grid may be provided in
form of a mesh with a potential applied thereto. The potential
decelerates the ions. The decelerated ions may pass through
openings in the grid. A charged grid mounted between the injector
and the wafer boat can, thus, reduce the energy and the momentum to
a desired level.
[0103] For the embodiments relating to plasma assisted processes,
UV assisted processes or ion assisted processes, the electrode
formed by the elements of the injector and the exhaust may be
grounded, whereas the other electrode is biased. Elements of the
injector or exhaust assembly may be an anode or a cathode for
plasma generation, UV generation or ion generation. Generally, it
is to be understood that either one of the anode or the cathode may
be grounded.
[0104] While the foregoing is directed to embodiments of the
invention, other and further embodiments of the invention may be
devised without departing from the basic scope thereof, and the
scope thereof is determined by the claims that follow.
* * * * *