U.S. patent application number 10/992005 was filed with the patent office on 2005-05-12 for atmospheric substrate processing apparatus for depositing multiple layers on a substrate.
This patent application is currently assigned to Applied Materials, Inc.. Invention is credited to Barnes, Michael, Cox, Michael S., Lai, Canfeng, Parks, John.
Application Number | 20050098115 10/992005 |
Document ID | / |
Family ID | 25471366 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050098115 |
Kind Code |
A1 |
Barnes, Michael ; et
al. |
May 12, 2005 |
Atmospheric substrate processing apparatus for depositing multiple
layers on a substrate
Abstract
A substrate processing apparatus is disclosed. In one
embodiment, the apparatus includes a first atmospheric deposition
station and a second atmospheric deposition station. The second
atmospheric deposition station comprises an atmospheric pressure
vapor deposition chamber. A substrate handling system is adapted to
transfer substrates between the first and the second atmospheric
deposition stations.
Inventors: |
Barnes, Michael; (San Ramon,
CA) ; Cox, Michael S.; (Davenport, CA) ; Lai,
Canfeng; (Fremont, CA) ; Parks, John; (San
Jose, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
25471366 |
Appl. No.: |
10/992005 |
Filed: |
November 17, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10992005 |
Nov 17, 2004 |
|
|
|
09938399 |
Aug 23, 2001 |
|
|
|
6841006 |
|
|
|
|
Current U.S.
Class: |
118/719 |
Current CPC
Class: |
C30B 25/08 20130101;
Y10S 414/139 20130101; C23C 16/54 20130101; H01L 21/67167 20130101;
H01L 21/67184 20130101 |
Class at
Publication: |
118/719 |
International
Class: |
C23C 016/00 |
Claims
1-15. (canceled)
16. A method for processing a substrate using a substrate
processing apparatus, the method comprising: (a) depositing a first
layer on a substrate at atmospheric pressure at a first atmospheric
deposition station; (b) transferring the substrate to an
atmospheric vapor deposition chamber at a second atmospheric
deposition station using a substrate transfer system; and (c)
depositing a second layer on the substrate at atmospheric pressure
within the atmospheric vapor deposition chamber at atmospheric
pressure.
17. The method of claim 16 wherein the substrate is a semiconductor
substrate.
18. The method of claim 16 wherein the first atmospheric deposition
station comprises a spin coating chamber.
19. The method of claim 16 further comprising: forming a porous
dielectric layer from the deposited first layer, and wherein
depositing the second layer on the substrate comprises depositing
the second layer on the porous dielectric layer.
20. The method of claim 19 wherein the porous layer and the cap
layer comprise dielectric materials.
21. The method of claim 16 further comprising: curing the first
layer at a curing station.
22. The method of claim 16 wherein the atmospheric vapor deposition
chamber is an atmospheric chemical vapor deposition (APCVD)
chamber.
23. The method of claim 16 wherein depositing the first layer
comprises depositing a liquid on the substrate.
Description
BACKGROUND OF THE INVENTION
[0001] A typical semiconductor fabrication facility can cost
billions of dollars. In view of the high capital costs associated
with building and maintaining a semiconductor fabrication facility,
it would be desirable to decrease the time needed to process
semiconductor wafers into chips. By reducing the cycle time for
chip production, more chips can be produced in less time, thus
maximizing the use of equipment in a fabrication facility.
[0002] One time-consuming processing step in a chip manufacturing
process is the evacuation and re-pressurization of load-locks,
transfer chambers, and processing chambers. For example, FIG. 1
shows a deposition module 120 that can be used to deposit layers on
semiconductor substrates. In operation, a loadlock chamber 124 in a
front end staging area 122 is loaded with cassettes containing
semiconductor substrates and is pumped down to near vacuum. The
front staging area 122 can be connected to another processing
module (not shown).
[0003] A transfer chamber 126 adjacent to the staging area 122 is
pumped down to vacuum or near vacuum using one or more vacuum pumps
(not shown) disposed on the deposition module 120. After vacuum
pumping to a sufficiently low pressure, the vacuum doors 128 of the
transfer chamber 126 open so that the transfer chamber 126 and the
front end staging area 122 are in communication with each other.
Movable arms on a substrate handler 127 in the transfer chamber 126
retrieve substrates from the loadlock chamber 124. The substrate
handler 127 in the transfer chamber 126 then transfers the
substrates into the processing regions 618, 620 of one of the
processing chambers 130.
[0004] Once the semiconductor substrates are placed in the
processing chambers 130, the arms of the substrate handler 127 are
withdrawn. The slit valves 132 to the processing chamber 130 are
then closed. Other processing chambers may be loaded with
substrates in a similar manner. In each processing chamber 130,
layers of material (e.g., capping layers) are respectively
deposited on the substrates using, for example, a plasma enhanced
chemical vapor deposition (PECVD) process. After processing is
finished, the slit valves 132 are opened and the arms of the
substrate handler 127 retrieve the substrates from the processing
regions 618, 620. The substrates are then returned to the loadlock
chamber 124. Then, the substrate handler 127 retrieves another pair
of substrates from the loadlock chamber 124, and the processing
continues in the same manner.
[0005] After all of the substrates in the loadlock chamber 124 are
processed, the slit valves 132 to the processing chambers 130 are
closed. The transfer chamber 126 is then vented to atmosphere
pressure using an inert gas (e.g., argon) and the front vacuum
doors 128 are opened. Another substrate handler (not shown) can
then retrieve the processed substrates from the loadlock chamber
124.
[0006] A significant amount of time is needed to evacuate and
re-pressurize the processing chambers, the transfer chamber, and
the loadlock chambers in the substrate processing apparatus. It
would be desirable to reduce the time associated with one or more
of these steps to reduce the amount of time needed to process the
substrate. Doing so would increase processing efficiency and would
reduce the cycle time associated with manufacturing, for example,
semiconductor chips.
[0007] Embodiments of the invention address this and other
problems.
SUMMARY OF THE INVENTION
[0008] Embodiments of the invention are directed to apparatuses and
methods for processing substrates.
[0009] One embodiment of the invention is directed to an apparatus
for processing a substrate, the apparatus comprising: (a) a first
atmospheric deposition station; (b) a second atmospheric deposition
station comprising an atmospheric pressure vapor deposition
chamber, wherein the first atmospheric deposition station and the
second atmospheric deposition station are coupled together; and (c)
a substrate handling system adapted to transfer substrates between
the atmospheric deposition station and the second atmospheric
deposition station.
[0010] Another embodiment of the invention is directed to an
apparatus for processing semiconductor substrates, the apparatus
comprising: (a) an atmospheric chemical vapor deposition chamber;
(b) a plasma system associated with the atmospheric chemical vapor
deposition chamber; (c) a spin coating chamber coupled to the
atmospheric deposition chamber; (d) a curing station coupled to the
atmospheric deposition chamber; and (e) a substrate handling system
adapted to transfer substrates between the atmospheric deposition
chamber, the spin coating chamber, and the curing station.
[0011] Another embodiment of the invention is directed to a method
for processing a substrate using a substrate processing apparatus,
the method comprising: (a) depositing a first layer on a substrate
at atmospheric pressure at a first atmospheric deposition station;
(b) transferring the substrate to an atmospheric vapor deposition
chamber at a second atmospheric deposition station using a
substrate transfer system; and (c) depositing a second layer on the
substrate at atmospheric pressure within the atmospheric vapor
deposition chamber at atmospheric pressure.
[0012] These and other embodiments of the invention are described
in further detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows a top view of a deposition module including
process chambers.
[0014] FIG. 2 shows a top view schematic view of a substrate
processing apparatus according to an embodiment of the
invention.
[0015] FIG. 3 shows a side schematic view of a pancake induction
atmospheric pressure chemical vapor deposition reactor.
[0016] FIG. 4 shows a side schematic view of a horizontal
conduction atmospheric pressure chemical vapor deposition
reactor.
[0017] FIG. 5 shows a side schematic view of a continuous
atmospheric pressure chemical vapor deposition reactor.
[0018] FIG. 6 shows side cross-sectional views of layers that can
be deposited using an apparatus according to an embodiment of the
invention.
DETAILED DESCRIPTION
[0019] Embodiments of the invention are directed to substrate
processing apparatuses and methods for processing substrates. In
one example, the apparatus comprises a first atmospheric deposition
station and a second atmospheric deposition station. The second
atmospheric deposition station comprises an atmospheric pressure
vapor deposition chamber. An atmospheric pressure vapor deposition
process such as an atmospheric pressure chemical vapor deposition
(APCVD) process can be performed in the chamber.
[0020] Substrates are transferred between the first and second
atmospheric deposition stations using a substrate handling system.
The substrate handling system, or parts of the substrate handling
system, may be housed in one or more transfer chambers. In the
apparatus, the substrates may be directly or indirectly transferred
from one atmospheric deposition station to another atmospheric
deposition station. In a typical indirect transfer of substrates,
substrates can be processed at an intermediate processing station
after being processed at a first atmospheric deposition station,
but before being processed at a second atmospheric deposition
station. For example, a spin coating process may be performed at a
first atmospheric deposition station, a curing process may be
performed at an intermediate processing station, and an APCVD
process may be performed at a second atmospheric deposition
station.
[0021] In embodiments of the invention, the first atmospheric
pressure deposition station may be directly or indirectly coupled
to the second atmospheric deposition station. For example, the
first and the second atmospheric deposition stations may be
indirectly coupled together using one or more intervening process
or transfer stations. The intervening stations may include, for
example, process chambers (e.g., curing chambers) or transfer
chambers that are disposed between the first and second atmospheric
deposition stations. Together, the first atmospheric deposition
station, the second atmospheric deposition station, and any
optional processing or transfer stations may form a cluster
tool.
[0022] Layers of material may be deposited at the first atmospheric
station using any suitable process and any suitable process
equipment. For example, the first atmospheric deposition station
can have a liquid dispenser to dispense liquids. In this regard,
the first atmospheric deposition station may include, for example,
a spin coater with a spin coating chamber, a spray coater (e.g., an
ultrasonic spray coater), a roller coater, or a curtain coater. In
some embodiments, the liquid dispenser may have one or more
nozzles. The one or more nozzles can dispense streams or droplets
of liquid (e.g., a spray) on a substrate to form a first layer on
the substrate.
[0023] The second atmospheric deposition station can comprise an
atmospheric pressure vapor deposition chamber. In the chamber, a
layer can be deposited using gas phase reactants. For example, an
APCVD process or a plasma enhanced APCVD process may be performed
at the second atmospheric deposition station to deposit a second
layer on the substrate. The deposited first and second layers may
be in direct contact with each other on the substrate or may be
coupled together through one or more intervening layers.
[0024] Embodiments of the invention have a number of advantages. As
the apparatus comprises a number of atmospheric deposition
stations, processing chambers at these stations need not be
evacuated and re-pressurized. The time associated with evacuating
and re-pressurizing many different chambers is eliminated or
reduced. As a result, substrates can be processed quickly and
efficiently. Also, the apparatus embodiments have fewer vacuum
pumps than conventional substrate processing apparatuses. For
example, in some embodiments, all processing stations in the
apparatus can process substrates at atmospheric pressure and no
vacuum pumps are present in the apparatus. Reducing the number of
vacuum pumps and other hardware associated with the vacuum pumps
reduces the overall complexity of the apparatus. In addition, by
using the substrate handling system to transfer substrates between
the various processing stations in the apparatus, substrates can be
processed continuously and automatically. Embodiments of the
invention can generally provide higher throughout, smaller
footprint, and lower costs than other conventional substrate
processing apparatuses.
[0025] An example of a substrate processing apparatus according to
an embodiment of the invention can be described with reference to
FIG. 2. FIG. 2 shows an apparatus including a first process module
101 and a second process module 210. In this example, the first
process module 101 and the second process module 210 are coupled
together via a curing chamber 116.
[0026] When the apparatus processes a substrate, a first layer can
be deposited on a substrate at a first atmospheric deposition
station in the first process module 101. The substrate is typically
a semiconductor substrate (e.g., a silicon wafer) and the first
layer may be, for example, a sol-gel layer. Other processing
stations may process the sol-gel layer into a porous dielectric
layer. A second layer can be deposited on the substrate at a second
atmospheric deposition station in the second process module 210.
The second layer may be, for example, a capping layer. The capping
layer may be on the substrate and in contact with the porous
dielectric layer. Sol-gel layers, porous dielectric layers, and
capping layers are examples of the many layers that may be
deposited and formed using embodiments of the invention. These
particular layers are described in greater detail below.
[0027] In the apparatus example shown in FIG. 2, the first process
module 101 includes a plurality of processing stations and a
transfer chamber 108. Each processing station may include a
processing chamber. In this example, the first process module 101
includes a cooling station comprising a cooling chamber 111, a spin
coating station having spin coating chambers 114, a curing station
having a curing chamber 116, a stripping/annealing station having a
stripping/annealing chamber 118, and a silylation station having a
silylation chamber 123. Further details about exemplary process
modules and the processing chambers in the first process module can
be found in U.S. patent application Ser. No. 09/502,126, filed Feb.
10, 2000, which is assigned to the same assignee as the present
invention and is herein incorporated by reference in its entirety
for all purposes. In the example shown in FIG. 2, the various
process chambers 111, 114, 116, 118, 123 are arranged around the
transfer chamber 108. Each process chamber 111, 114, 116, 118, 123
is in communication with the interior of the transfer chamber 108
through various slits 110, 113, 117, 119, 121.
[0028] A substrate handler 112 with arms is present in the transfer
chamber 108. The arms of the substrate handlers 112 can move in a
radial direction to insert substrates into the various process
chambers 111, 114, 116, 118, 123 or remove substrates from them. In
this example, the substrate handler 112 has two arms with
independent rotational movement. Alternatively, the two armed
substrate handler 112 may have arms that move in tandem.
[0029] In the apparatus shown in FIG. 2, the spin coating station
comprising the spin coating chambers 114 may be considered a first
atmospheric deposition station. A spin coating process can be used
to deposit a liquid on a substrate at atmospheric pressure in each
of the spin coating chambers 114. In a typical spin coating
process, a liquid is dispensed onto a substrate and is initially
deposited as a puddle or stream over one part of the substrate.
During or after liquid deposition, the substrate spins and
centrifugal forces distribute the liquid evenly across the surface
of the spinning substrate to form a coating on the substrate. The
coated substrate can then be baked or cured in the curing chamber
116. The baking or curing process may also be performed at
atmospheric pressure. Accordingly, in some embodiments of the
invention, some or all of the stations and chambers in the
apparatus may operate at atmospheric pressure.
[0030] In other embodiments, the first atmospheric deposition
station can have an ultrasonic spray chamber (not shown). An
ultrasonic spraying process may be used to form a layer on a
substrate. In an ultrasonic spraying process, an ultrasonic spray
nozzle is positioned above the substrate and breaks up the process
liquid into a fine mist. The spray nozzle is on an arm that moves
from the center to the edge of the wafer, or vice-versa. During
spraying, a spray envelope extends over a broad area of the
substrate so that the entire surface of the substrate can be
covered with the sprayed liquid. The substrate may or may not be
rotated while spraying.
[0031] Compared with conventional pressure spray nozzles,
ultrasonic nozzles deliver a low-velocity spray. For example, in a
typical ultrasonic spray process, the spray velocity is
approximately {fraction (1/100)}.sup.th of that produced by an
ordinary pressure nozzle so excess spraying is minimized.
Minimizing overspraying reduces the amount of liquid that is
released into the environment and reduces the amount of liquid that
is wasted during processing. Also, because overspaying is
minimized, the amount of liquid deposited on the backside of the
substrate is minimized. This can eliminate the need for, or reduce
the time associated with, a subsequent back side rinse process. In
a back side rinse process, the back surface of a substrate is
rinsed of any liquid that was previously deposited on the front
surface of the substrate.
[0032] The stripping/annealing chamber 118 is capable of performing
one or both of a non-reactive gas anneal and an oxidizing gas strip
of a deposited layer. An example of a stripping/annealing chamber
118 is the WxZ.TM. chamber that is commercially available from
Applied Materials, Inc., of Santa Clara, Calif. Undesired
substances may be removed from a deposited layer using an annealing
or a stripping process. For example, during the formation of a
mesoporous oxide layer, surfactants can be removed from a cured
sol-gel layer by annealing the cured layer and/or exposing the
cured layer to an oxidizing atmosphere. A high temperature anneal
can also transform a cured sol-gel layer into a mesoporous oxide
layer.
[0033] The silylation chamber 123 can be used to perform a
silylation process. In a silylation process, a layer on a substrate
is exposed to a silylating agent. Examples of silylating agents
include tetramethyl disilazane (TMDS), hexamethyl disilazane
(HMDS), and dimethylaminotrimethyl silane, and combinations
thereof. During silylation, the substrate may be at a temperature
of about 25.degree. C. to about 200.degree. C. Many mesoporous
oxide layers, for example, are hydrophilic after they are formed.
Silylating a hydrophilic layer on a substrate can render the layer
hydrophobic. Hydrophobic layers are less likely to retain moisture
than hydrophilic layers. As explained in further detail below,
moisture can affect the properties of dielectric and conductive
layers in an interconnect structure.
[0034] The first process module 101 may also include a front
staging area 102 coupled to the transfer chamber 108. Substrate
handlers 104 are in the front staging area 102. The substrate
handlers 104 can transfer substrates between substrate cassettes
106 that are coupled to the front staging area 102 and the cooling
chamber 111. The substrate cassettes 106 are adapted to support a
plurality of substrates mounted in a spaced vertical arrangement. A
substrate rest 103 is disposed between the handlers 104 to provide
a cooling rest for substrates during substrate exchange between the
cooling chamber 111 and the cassettes 106. Alternatively, the
substrate rest 103 may preheat the substrates for subsequent
processing. The cooling chamber 111 may cool the substrates for
subsequent processing or prior to exiting the apparatus.
[0035] The second process module 210 includes one or more
atmospheric pressure vapor deposition stations 205 that are coupled
together through a transfer chamber 133. Each station 205 includes
an atmospheric pressure vapor deposition chamber 202 and an
optional remote plasma chamber 201. Each atmospheric pressure vapor
deposition station 205 may have one or more gas distribution
assemblies (not shown). The gas distribution assemblies may
uniformly distribute process gases onto the substrates within the
atmospheric pressure vapor deposition chambers 202. A substrate
handler 127 is in the transfer chamber 133 and inserts substrates
into or retrieves substrates from the atmospheric vapor deposition
chambers 202. Having the substrate handler 127 in the transfer
chamber 133 reduces the likelihood that contamination from the
outside environment may deposit on the substrates being handled.
The substrate handler 127 may be the same or different than the
previously described substrate handlers.
[0036] The atmospheric pressure vapor deposition processes
performed in the atmospheric vapor deposition chambers 202 may be
non-reactive or reactive. Examples of non-reactive deposition
processes include evaporation and sputtering. In other embodiments,
a reactive deposition process may be performed in the processing
chamber. Examples of reactive deposition processes include
atmospheric pressure chemical vapor deposition (APCVD) processes
and plasma enhanced APCVD processes. APCVD processes are especially
suitable for forming compound layers, i.e. layers of materials
formed from at least two different elements such as silicon
nitride, silicon oxynitride, silicon dioxide, aluminum oxide,
aluminum nitride, titanium oxide, etc.
[0037] In an APCVD process, a non-volatile solid layer is formed on
a substrate by a surface reaction of gaseous reactants. A typical
APCVD process comprises (1) introducing gaseous reactants and inert
carrier gas into a reaction chamber, (2) transporting gaseous
reactants to the surface of the substrate, (3) adsorbing reagent
species onto the substrate where they undergo migration and film
forming reactions, and (4) removing gaseous reaction byproducts and
unused reactants from each chamber. The APCVD chamber is at or near
atmospheric pressure during deposition.
[0038] In general, APCVD processes have higher deposition rates
than LPCVD (low pressure chemical vapor deposition) processes.
Accordingly, APCVD processes can deposit a layer of material on a
substrate faster than typical LPCVD processes. In order to improve
the uniformity of the layers deposited using APCVD processes, the
reactant gases in the chamber can be agitated and/or the substrate
being processed can be moved during the deposition process. For
example, many APCVD apparatuses have a moving substrate holder that
supports and moves substrates during the deposition process.
[0039] The substrate can be heated in an APCVD process to drive the
reaction at the surface of the substrate. For faster reaction
rates, the substrates are typically heated to temperatures ranging
from about 500.degree. C. to as high as about 1600.degree. C. Heat
is supplied to the substrate in any suitable manner. For example,
heat can be supplied to the substrate by heating a susceptor that
supports the substrate. The susceptors can be heated by, for
example, resistive or inductive heating.
[0040] Process parameters such as the process gas composition, the
process gas flowrates, the substrate temperature, and the chamber
wall temperatures may be adjusted according to the particular
layers being deposited. In this regard, specific processing recipes
can be created for the particular layers being deposited. The
particular recipes can be created and stored in a computer at the
atmospheric deposition station and can be determined by those of
ordinary skill in the art.
[0041] Any suitable APCVD reactor can be used in the atmospheric
vapor deposition station 205. Examples of APCVD reactors include
cold-wall induction APCVD reactors, pancake induction heated APCVD
reactors, continuous conduction heated APCVD reactors, and
horizontal conduction heated APCVD reactors. These reactors are
well known in the art. Some examples of suitable APCVD reactors are
shown in FIGS. 3 and 4.
[0042] FIG. 3 shows an example of a pancake induction heated APCVD
system. In the illustrated APCVD system, semiconductor substrates
307 are on a rotating holder 308 of graphite. Both the substrates
307 and the rotating holder 308 are present within an APCVD chamber
303. The graphite holder 308 is heated by induction using an RF
coil (not shown) below the holder 308. Reaction gases 309 are fed
through a tube 305 under the holder 308 and exit the holder 308
above the substrates 307. The holder 308 rotates and the reactant
gases 309 react at the surface of the substrates 307 to form layers
of material.
[0043] In a pancake induction heated APCVD system, the reactant
gases flow vertically with respect to the substrate. Vertical gas
flow offers the advantage of a continuous supply of fresh reactants
to the wafers, thus minimizing downstream depletion. The
combination of the substrate rotation and the vertical flow of the
gases produces good uniformity in the deposited layer.
[0044] FIG. 4 shows an example of a horizontal conduction heated
APCVD system. In this embodiment, gases 317 are mixed outside of
the chamber 323 and the mixed gases 317 pass to a showerhead 315.
The showerhead 315 distributes the gases 317 on the substrates 320.
As this distribution occurs, a hot plate holder 313 moves back and
forth under the showerhead 315. The gases 317 react at the surfaces
of the substrates 320 to form layers of material on the substrates
320.
[0045] In some embodiments, the APCVD process is a plasma enhanced
APCVD process. In a plasma enhanced APCVD process, energy is
applied to reactant gases to form a plasma containing reactive
ions. The plasma may be generated in the deposition chamber or may
be generated in a remote chamber. The remote chamber is positioned
upstream of the deposition chamber. For example, in the embodiment
illustrated in FIG. 2, a plasma is formed in the remote plasma
chamber 201 that is upstream of a corresponding deposition chamber
202. The plasma in the remote plasma chamber 201 may be generated
using any suitable form of energy. For example, RF (radio
frequency), RF resonant, microwave, or corona energy may be used to
generate a plasma. The formed gaseous ions can pass downstream of
the remote plasma chamber 201 and into the atmospheric vapor
deposition chamber 202 where they react at the surface of the
substrate. In general, plasma enhanced processes can deposit layers
on a substrate more quickly and at lower temperatures than
non-plasma enhanced processes.
[0046] Any suitable substrate handling system can be used in the
apparatus to facilitate the movement and transfer of the substrates
between the processing stations and chambers within the apparatus.
For example, the substrate handling system may comprise any
suitable combination of track systems, conveyor belts, armed
substrate handlers, etc. Such components may operate dependently or
independently of each other. For instance, in the apparatus shown
in FIG. 2, the substrate handling system includes a first substrate
handler 112 and a second substrate handler 127. The first and
second substrate handlers 112, 127 may work independently or
dependently to transfer substrates from the spin coating chambers
114 of the first process module 101 to the atmospheric deposition
chambers 202 of the second process module 210.
[0047] In other embodiments, a plurality of different process
stations may be separated from each other by conveyor belts and
substrate handlers that transfer the substrates between adjacent
stations. Illustratively, a spin coating chamber, a curing chamber,
a stripping/annealing chamber, and an APCVD chamber may form a
process line. Substrates can be transferred between adjacent
chambers using conveyors and/or substrate handlers that are
disposed between the chambers. Substrates can be sequentially
processed in the spin coating chamber, curing chamber,
stripping/annealing chamber, and the APCVD chamber. In these and
other embodiments, a batch of substrates can be substantially
continuously processed without manual intervention.
[0048] An example of an APCVD reactor that can be used in a
continuous process line is shown in FIG. 5. FIG. 5 shows a reaction
chamber 510 that receives process gases 507. A noble gas (e.g.,
argon or nitrogen) "curtain" 505 can be disposed on opposite sides
of the reaction chamber 510 to confine the process gases 507.
Substrates 513 can pass under the process gases 510 as they are
transported by a conveyor belt 503. A heater 501 may be under the
conveyor belt 503 to heat the substrates 513 on a conveyor belt 503
to a suitable process temperature. Using the apparatus shown in
FIG. 5, substrates can be processed in a truly continuous fashion.
For example, substrates can be loaded at one end of the reactor and
then unloaded at another end of the reactor using substrate
handlers. The substrates can be transferred to the reactor from a
preceding process station and away from the reactor to another
subsequent process station using conveyors. Thus, one or more other
process stations may be coupled to either end of the reactor so
that more than one layer of material can be deposited on the
substrates 513 in an automated processing sequence. For example, a
spin coating station or an ultrasonic spray station may be precede
and may be coupled to the reactor shown in FIG. 5 to form an
apparatus that can deposit multiple layers on substrates.
[0049] As noted, a first layer may be formed on a substrate at the
first atmospheric deposition station and a second layer may be
formed on the substrate at the second atmospheric deposition
station. The first and second layers may have any suitable
characteristics. For example, each of the first layer and the
second layer may be a dielectric or conductive layer, or a
precursor to a dielectric or conductive layer. Either layer may be
porous or solid. In addition, if the first or the second layer
comprises or is formed into a dielectric layer, the dielectric
layer may comprise materials such as silicon dioxide, silicon
nitride, silicon oxynitride, metal oxides such as titanium oxide,
etc.
[0050] In some embodiments, the first layer and the second layer
may both be layers with dielectric properties. For example, the
first layer may be a dielectric layer while the second layer may be
a dielectric capping or barrier layer. In other embodiments, the
first layer may comprise a dielectric material while the second
layer comprises a conductive material. In yet other embodiments,
the first and the second layers may both be conductive.
[0051] The first and the second layers may also be precursors to a
final layer or a final layer in a semiconductor chip. For example,
the first layer may be a precursor layer to a porous dielectric
layer such as a mesoporous oxide layer. The precursor layer may be
a sol-gel layer that is later formed into a dielectric mesoporous
oxide layer using additional processes such as curing and
stripping. The second layer may be a layer such as a dielectric
capping layer that is formed using an atmospheric vapor deposition
process. In this example, the dielectric mesoporous oxide layer and
the capping layer may be in direct contact with each other.
[0052] Mesoporous oxide layers and capping layers can be used in an
interconnect structure in a semiconductor chip. An exemplary
interconnect structure 400 is shown in FIG. 6. In FIG. 6, a first
mesoporous oxide 408 is on a substrate 402 that has a pattern of
conducting lines 404. A first capping layer 406 is between the
first dielectric layer 408 and the substrate 402. The first
dielectric layer 408 may comprise a mesoporous oxide. A second
capping layer 410 is on the first dielectric layer 408 and may have
the same or different characteristics as the first capping layer
406. A second dielectric layer 414 may comprise a mesoporous oxide
layer and is disposed over the second capping layer 410. A third
capping layer 416 is on the second dielectric layer 408. A
conductive via 417 and a barrier layer 420 may pass through the
capping layers and the dielectric layers. The conductive via 417
and the conducting lines 404 may comprise any suitable conductive
material including copper, aluminum, or tungsten. A fourth capping
layer 424 may be on the third capping layer 416. The barrier layer
and the capping layers may comprise any suitable material
including, for example, refractory metal nitrides (e.g., tantalum
nitride), refractory metals (e.g., tantalum, tungsten), silicon
carbides (e.g., amorphous silicon carbide), silicon oxides (e.g.,
silicon dioxide), silicon nitrides, silicon oxynitrides, etc.
[0053] Mesoporous oxide layers are desirable as dielectric layers.
They have a low dielectric constant and are suitable dielectric
barriers between copper layers. However, mesoporous oxide layers
are highly hydrophilic and are sensitive to moisture contamination.
Moisture contamination can alter the dielectric constant of a
dielectric layer. For example, if water, which has a dielectric
constant (k) of about 78, is absorbed by the mesoporous oxide
layer, then the low dielectric constant properties of the
mesoporous oxide layer can be unintentionally altered.
[0054] In general, moisture in a porous dielectric layer can be
generated during formation of the porous dielectric layer and can
remain within the pores of the layer. The moisture can diffuse to
the surface of an adjacent conductive metal layer and can increase
its resistivity. Accordingly, it is desirable to remove moisture
from porous dielectric layers such as mesoporous oxide layers.
Porous dielectric layers such as mesoporous oxide layers may be
annealed to remove moisture. However, it is more desirable to
deposit a capping layer on the porous layer and/or make the porous
layer hydrophobic. By doing so, additional moisture is inhibited
from entering the pores of the porous layer. In addition to serving
as a moisture barrier, the capping layer may also serve as an etch
stop layer or a hard mask during the fabrication of an interconnect
structure.
[0055] A method of forming mesoporous oxide layers and capping
layers on substrates using an apparatus embodiment can be described
with reference to FIG. 2. Referring to FIG. 2, substrate cassettes
106 containing substrates are coupled to the front staging area
102. The substrate handlers 104 index the substrates in each
substrate cassette 106. Once indexed, the substrate handlers 104
transfer the substrates to the cooling chamber 111.
[0056] The substrate handler 112 retrieves substrates from the
cooling chamber 110 and transfers the substrates to the spin
coating chambers 114. In the spin-coating chambers 114, sol-gel
layers are deposited on the substrates using spin coating
processes. Alternatively, the sol-gel layers can be formed using
spray coating processes (e.g., ultrasonic spray coating).
[0057] The sol-gel solution used to form the sol-gel layer can
contain a mixture comprising silicon/oxygen compounds, water, and a
surfactant in an organic solvent. An exemplary sol-gel solution may
be a mixture of tetraethylorthosilicate (TEOS), ethanol, water, and
a polyethylene oxide surfactant. An optional acid or base catalyst
may be further used in the formation of the sol-gel solution.
[0058] The silicon/oxygen compounds in the sol-gel solution are
those conventionally used in the deposition of silicon containing
layers in semiconductor manufacturing. Examples of silicon/oxygen
compounds include silica, tetraethoxysilane (TEOS),
phenyltriethyloxy silane, methyltriethoxy silane, etc.
[0059] Surfactants are used to disperse the silicon/oxygen
compounds in sol-gel solutions so that the concentration of
materials in the formed sol-gel layer are uniform. The surfactants
may be anionic, cationic, or non-ionic. Non-ionic surfactants have
chemical functional groups that are uncharged or neutral
hydrophilic groups while anionic and cationic surfactants have
functional groups respectfully charged negatively and positively.
Examples of suitable surfactants include primary amines,
polyoxyethylene oxides, ethylene glycol ethers, etc.
[0060] Any suitable solvent may be used in the sol-gel solution.
Examples of suitable solvents include organic solvents. Organic
solvents can be alcohols such as ethanol, n-propanol, iso-propanol,
n-butanol, sec-butanol, tert-butanol, ethylene glycol, etc.
[0061] Once the sol-gel solution has been deposited on the
substrates, the substrate handler 112 retrieves the substrates and
transfers the substrates to the curing chamber 116. The sol-gel
layers on the substrates are then cured to remove solvent and water
from the layers. During the curing step, organic solvent in the
layer evaporates and moisture in the layer is removed. This
increases the concentration of non-volatile surfactant and
silicon/oxygen compounds in the layer. In some embodiments, the
curing process may take place between about 50.degree. C. and about
450.degree. C. and may be performed for about one to ten minutes.
The cured sol-gel layer for each substrate has interconnecting
pores of uniform diameter.
[0062] Due to the length of curing process as compared to other
processes, a larger number of curing chambers 116 can be coupled to
the transfer chamber 108. For example, there may be eight curing
chambers per two dual substrate spin coating chambers 114. The
substrate handler 112 may be programmed to fill up the curing
chambers 116 with spin-on deposited substrates prior to processing
or may be programmed to load and unload substrates in the curing
chamber 116 as desired.
[0063] After curing, the substrates can be transferred to a
substrate stripping/annealing chamber 118. Annealing can be
performed in the chamber 118 to remove surfactant from the cured
sol-gel layer and to form a mesoporous oxide layer. For a high
temperature non-reactive gas anneal, the stripping/annealing
chamber 118 can be maintained at or near atmospheric pressure. The
oxygen concentration inside the stripping/annealing chamber 118 can
be controlled to less than about 100 ppm during annealing. In some
embodiments, annealing can take place between about 200.degree. C.
and about 450.degree. C. and for between about 30 seconds and about
30 minutes. In a typical rapid thermal annealing process, the
temperature of the substrate can increase at a rate of at least
50.degree. C. per second.
[0064] The cured sol-gel layer may also be exposed to an oxidizing
environment to remove surfactant from the layer and to transform it
into a mesoporous oxide layer. In a typical oxidation stripping
process, the stripping/annealing chamber 118 can be maintained at
about a pressure from about 1 Torr to about 10 Torr. The cured
sol-gel layer can be exposed to an oxidizing gas comprising, for
example, oxygen, ozone, or oxygen ions at high temperatures. The
oxidizing gas flow into the stripper/annealing chamber 118 can be
maintained at a high flow rate (e.g., greater than 20 liters/min)
to thoroughly expose the layer to the gas. In some embodiments, the
substrate may be heated to between about 200.degree. C. to about
450.degree. C. for between about 30 seconds and 30 minutes during
stripping.
[0065] In some embodiments, the oxidizing gas used in the stripping
process may comprise oxygen ions. The oxygen ions may be formed in
a plasma chamber using an RF generator or a microwave generator to
form a remote plasma. The formed oxygen ions pass downstream of the
plasma chamber into the stripping chamber. In the stripping
chamber, the oxygen ions react with any surfactant and solvent in
the layer to remove them from the layer. In some embodiments, if
oxygen ions are used in the stripping process, the substrate can be
exposed to the process gas for about 0.5 minutes to about 5 minutes
to remove the surfactant.
[0066] The formed mesoporous oxide layer is highly porous, and may
have a porosity of greater than 50%. It may also have a dielectric
constant of less than 2.5. For example, the mesoporous oxide layer
may have a dielectric constant of about 1.6 to about 2.2.
[0067] Optionally, the mesoporous oxide layer may be silylated in
the silylation chamber 123. As noted above, the mesoporous oxide
layer may be rendered hydrophobic by using a silylation
process.
[0068] After completing any stripping, annealing, or silylation
processes, the substrate handler 112 retrieves the substrates from
the stripping/annealing chamber 118 or the silylation chamber 123.
The substrate handler 112 in the first process module 101 may then
directly or indirectly transfer the substrates to the substrate
handler 127 in the second process module 210. The substrate handler
127 in the second process module 210 then places the substrates in
the APCVD chambers 202.
[0069] In the APVCD chambers 202, capping layers can then be
deposited over the mesoporous oxide layers on the substrates. For
example, reactant gases for plasma enhanced APCVD processes may be
fed to one of the plasma chambers 201. When the gases are in the
plasma chamber 201, ionizing energy may be applied to the gases to
form a plasma. The ions from the plasma pass downstream of the
plasma chamber 201 to the processing chamber 202. Once the ionized
process gases are in the processing chamber 202, they contact the
surfaces of the substrates and react on the surfaces to form layers
of material on the substrates. The substrates may be moving during
the deposition process to improve the thickness uniformity of the
deposited layers. Capping layers are then formed on the mesoporous
oxide layers on the substrates. The processing chamber 202 is at or
near atmospheric pressure during the deposition process.
[0070] In other embodiments, a plasma need not be formed in the
APCVD process. Illustratively, a silicon nitride capping layer can
be formed on a mesoporous oxide layer without forming a plasma. The
silicon nitride capping layer may be formed using silane and
ammonia process gases. These gases can be introduced to a
processing chamber and can react at the surface of the mesoporous
oxide layer on the substrate in the chamber. The substrate
temperature may be at about 700 to about 900.degree. C. during
deposition. A silicon nitride capping layer is subsequently formed
on the mesoporous oxide layer. In this embodiment, the reactant
gases need not be ionized to form the capping layer on the
substrate. During the deposition process, the chamber may contain
inert gases and may be at or near atmospheric pressure.
[0071] Although mesoporous oxide layer and capping layers are
described in detail above, it is understood that embodiments of the
invention are not limited to the formation of such layers on a
substrate. Embodiments of the invention can be used to form any
suitable combination of layers on a substrate.
[0072] The terms and expressions which have been employed herein
are used as terms of description and not of limitation, and there
is no intention in the use of such terms and expressions of
excluding equivalents of the features shown and described, or
portions thereof, it being recognized that various modifications
are possible within the scope of the invention claimed. Moreover,
any one or more features of any embodiment of the invention may be
combined with any one or more other features of any other
embodiment of the invention, without departing from the scope of
the invention.
* * * * *