U.S. patent application number 12/736176 was filed with the patent office on 2011-03-31 for electrochemical deposition system.
Invention is credited to Chuan He, Yue Ma, Voha Nuch, Zhenxu Pang, Guangtao Shi, Hui Wang, Jiexu Xia.
Application Number | 20110073469 12/736176 |
Document ID | / |
Family ID | 41090468 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110073469 |
Kind Code |
A1 |
Ma; Yue ; et al. |
March 31, 2011 |
ELECTROCHEMICAL DEPOSITION SYSTEM
Abstract
A electrochemical deposition system which has a 3-D stacked
architecture comprises a factory interface for receiving
semiconductor wafers, a mainframe comprising a mainframe transfer
robot and a plurality of wafer holder assemblies which disposed on
the top thereof, a plurality of electroplating cells disposed
within the mainframe, a plurality of cleaning cells disposed within
the mainframe and located below the electroplating cells, a
plurality of thermal treatment chambers disposed in between the
mainframe and the factory interface, and a fluid distribution
system fluidly connected to the electroplating cells and the
cleaning cells, wherein the mainframe transfer robot transfers the
semiconductor wafer from the factory interface and within the
electroplating cells, the cleaning cells, and the thermal treatment
chambers. As a result, the system of the present invention is
expandable to accommodate newly-added processing units without
overmuch increased footprint.
Inventors: |
Ma; Yue; (Shanghai, CN)
; He; Chuan; (Shanghai, CN) ; Pang; Zhenxu;
(Shanghai, CN) ; Shi; Guangtao; (Shanghai, CN)
; Xia; Jiexu; (Shanghai, CN) ; Nuch; Voha;
(Shanghai, CN) ; Wang; Hui; (Shanghai,
CN) |
Family ID: |
41090468 |
Appl. No.: |
12/736176 |
Filed: |
March 19, 2008 |
PCT Filed: |
March 19, 2008 |
PCT NO: |
PCT/CN2008/070531 |
371 Date: |
November 15, 2010 |
Current U.S.
Class: |
204/270 |
Current CPC
Class: |
C25D 17/001 20130101;
C25D 5/48 20130101; C25D 17/04 20130101; C25D 21/02 20130101; C25D
17/02 20130101; H01L 21/67178 20130101; C25D 17/00 20130101; H01L
21/6723 20130101; C25D 5/50 20130101 |
Class at
Publication: |
204/270 |
International
Class: |
C25D 17/00 20060101
C25D017/00 |
Claims
1. An electrochemical deposition system which has a 3-D stacked
architecture comprising: a factory interface for receiving
semiconductor wafers; a mainframe comprising a mainframe transfer
robot and a plurality of wafer holder assemblies for holding
semiconductor wafers in an electroplating process which disposed on
the top thereof; a plurality of electroplating cells disposed
within a first layer of the 3-D stacked architecture at the upper
part of the mainframe; a plurality of cleaning cells disposed
within a second layer of the 3-D stacked architecture at the lower
part of the mainframe; a plurality of thermal treatment chambers
disposed within either said first or the second layer and connected
to the factory interface; at least one vapor phase pre-wet device;
a fluid distribution system to provide electrolyte solutions to the
electroplating cells and to provide process fluids to the cleaning
cells respectively; and a gas delivery system to provide a gas
mixture to the thermal treatment chambers; wherein, the mainframe
transfer robot transfers semiconductor wafers from the factory
interface between the wafer holder assemblies, the cleaning cells,
the thermal treatment chambers, and delivery and storage
cassettes.
2. The system of claim 1, wherein the electroplating cell further
comprises an electrolyte chamber comprising a plurality of annular
insulating walls which separate the electrolyte chamber into a
plurality of independent regions and a plurality of annular
electrodes respectively disposed within each said independent
region and separated into an upper cell body receiving catholyte
and a lower cell body receiving anolyte by a bubble coalescence
assembly which is used to collect and remove the bubbles generated
from the electrolyte chamber.
3. The system of claim 2, wherein said bubble coalescence assembly
comprises a cone-shape frame configured with pluralities of V-shape
grooves and an porous membrane attached on the cone-shape
frame.
4. The system of claim 2, wherein the anodes are independently
charged by a plurality of power supplies.
5. The system of claim 2, wherein the upper cell body of said
electrolyte chamber is configured with a plurality of electrolyte
inlets for introducing electrolyte into said regions, wherein flows
of electrolyte are controlled independently.
6. The system of claim 1, wherein said system comprises a vapor
phase pre-wet device independently disposed on the mainframe or
integrated on the wafer holder assembly and used for pre-wetting
front surface of a wafer before electroplating process.
7. The system of claim 1, wherein the thermal treatment chamber
further comprises: at least one heating plate for heating a
semiconductor wafer; at least one cooling plate for cooling the
semiconductor wafer; at least two workpiece holders for receiving
the wafer and transferring the semiconductor wafer from the heating
plate to the cooling plate; and at least two actuators for
controlling the movement of the semiconductor wafer holder.
8. The system of claim 7, wherein the thermal treatment chamber has
a cooling window faced against the factory interface and a heating
window faced against the mainframe.
9. The system of claim 1, wherein said system comprises a plurality
of wafer cassettes attached to the factory interface and disposed
over the thermal treatment chambers to facilitate transfer and
storage of semiconductor wafers between the factory interface and
the mainframe.
10. The system of claim 1, wherein said factory interface
comprises: a plurality of load ports where semiconductor wafers are
positioned; at least one semiconductor wafer aligner for orienting
semiconductor wafers; and a front interface robot that transfers a
semiconductor wafer from a wafer pod to the wafer aligner, or from
the wafer aligner to the transfer cassettes, or from the thermal
treatment chamber to the load port.
11. The system of claim 1, wherein one of the cleaning cells
correspondingly located right below one of the electroplating
cells.
12. The system of claim 1, wherein said cleaning cell provides spin
rinse cleaning and removing the unwanted edge deposition of
metals.
13. The system of claim 1, wherein said fluid distribution module
comprises a maintank for providing electroplating electrolyte to
the electroplating cells.
14. The system of claim 13, wherein said maintank further comprises
a catholyte cell for providing catholyte to the upper cell body and
an anolyte cell for providing anolyte to the electrolyte
chamber
15. The system of claim 13, wherein said fluid distribution module
further comprises a chemical mixing room to mix chemicals that will
be introduced into the cleaning cell to etch off the deposited
metal film on the bevel of a semiconductor wafer.
16. The system of claim 13, wherein said system further comprises a
metrology tool and an dosing system, the maintank is fluidly
connected to the metrology tool which monitors the concentration of
components of the fluid in the maintank, and the dosing system
which provide electrolyte components to the maintank according to
user input, the information about concentration outputted by the
metrology tool, and the desired concentration of components of the
electrolyte in the maintank.
Description
FIELD OF INVENTION
[0001] The present invention relates to a system for deposition of
a metallic layer onto semiconductor workpieces, more particularly a
system for electrochemical or electroless deposition of metallic
thin films on semiconductor wafers from electrolyte solutions,
chemically etching parts of the deposited films, cleaning the
surface of the deposited films and thermally treating the deposited
films.
RELATED ART
[0002] On-chip interconnects comprises multilayer of metallic
wirings embedded in one or more insulating materials on the top of
transistor circuit of logic or memory chips. As the circuit density
in ultra large scale integrated (ULSI) circuits increases, the size
of the features in the pattern of metallic wirings, such as vias
and trenches, decreases to submicron level, and the levels of
metallization increase. Furthermore, RC delay has become the most
dominant effect in degrading the circuit speed as the length of
conductive wirings in integrated circuits continues to grow. Copper
is a favorable material for interconnect metallization because of
its low resistivity and high electromigration resistance. While
copper is good for interconnect metallization, it poses many
challenges to metallization during device fabrication.
[0003] The main challenge for copper implementation is the
deposition system to uniformly fill trench and via features without
voids and seams across the entire semiconductor substrate, known as
wafer, in a damascene process, or frequently dual damascene process
at acceptable manufacture flow cost.
[0004] Typical electroplating systems usually comprise a plurality
of plating cells for metal electrochemical or chemical
("electroless") deposition and cleaning cells for rinse, clean and
bevel etch after deposition.
[0005] Examples of such electroplating systems are disclosed in
U.S. Pat. No. 6,258,220 and U.S. Pat. No. 6,527,920. Such systems
include a mainframe with a mainframe transfer robot, a loading
station disposed in connection with the mainframe, a plurality of
electrochemical processing cells disposed in connection with the
mainframe, a plurality of spin-rinse-dry and bevel etch chambers
disposed in the mainframe, and a rapid thermal treatment subsystem
attached adjacent the loading station. The locations of the
processing cells, spin-rinse-dry and bevel etch chambers and the
probably added units are designed in one plane, and such a design
takes large clean room space for providing satisfactory throughout
to meet the demands of the processing system. Said electroplating
systems are used in today's IC manufacturing.
[0006] Because such a system utilizes a 2-D architecture with all
process units placed on one plane, while it is expanded to
accommodate newly added process units, the footprint of the system
increases, thereby limiting its expandability practically.
Additionally, a plurality of permanent heavy-duty supporting posts,
erected from the base plate where the processing chambers are built
upon, are needed in said electroplating system to support a
plurality of plating cell head assemblies that receive wafers from
a robot and carry the wafers into the electrolyte. These posts are
bulky as they must provide stabilization and consistence to the
cell head assemblies they support in order to control precisely the
movement of the cell head assemblies. These supporting posts not
only take spaces inside the frame enclosure, but also limit the
reachability to the mainframe transfer robot, the wafer holder
assemblies and the plating cells and make the maintenance of the
system inconvenient.
[0007] Furthermore, when the dimensions of the vias and trenches in
the pattern on a semiconductor wafer become smaller, the features
of the wafer become difficult to be completely wetted when the
wafer carried by the chuck of the wafer holder assembly immerses
into the electrolyte. This incomplete wetting will lead to defects
and voids in the features in the deposited metal films. An typical
method to wet a wafer is to pre-rinse the wafer in an added
spin-rinse-dry cell before electroplating, as described in US
2004/0069644 and US 2007/7223323. And another example of method to
wet a wafer is splashing water to the wafer surface by an added
nozzle just before the wafer is carried into plating electrolyte,
as described in US 2006/7146994. But pre-wetting by liquid rinse
still cannot wet very small features completely, and the rinse
liquid may dilute the plating electrolyte both globally in a high
volume factory and locally, leading to new problems. So these
disclosed methods still cannot completely solve the problem of
incomplete wetting without significantly introducing process
variation and adding manufacturing cost.
[0008] The present invention was disclosed against this
background.
SUMMARY
[0009] In view of the aforementioned problems, it is an object of
the present invention to provide a new architecture of an
electrochemical deposition system that may treat larger scale
semiconductor wafers with great efficiency to provide high
throughput with a small footprint.
[0010] In order to achieve the aforementioned object, an
electrochemical deposition system according to the present
invention which has a three dimensional (3-D) stacked architecture
that comprises a factory interface for receiving semiconductor
wafers, a mainframe comprising a mainframe transfer robot, a
plurality of wafer holder assemblies which are disposed on the top
thereof, a plurality of electroplating cells disposed within a
first layer of the 3-D stacked architecture at the upper part of
the mainframe, a plurality of cleaning and bevel etch cells
disposed within a second layer of the 3-D stacked architecture at
the lower part of the mainframe, a plurality of thermal treatment
chambers disposed within either the first layer, or the second
layer, or both layers in the part of the mainframe connected to the
factory interface, a plurality of vapor phase pre-wetting modules
disposed within the mainframe, a fluid distribution system to
provide electrolyte to the plating cells and process fluids to the
cleaning cells, a gas delivery system to provide gas mixture to the
thermal treatment chambers. The mainframe transfer robot transfers
the semiconductor wafers between the factory interface, the wafer
holder assemblies, the cleaning cells and the thermal treatment
chambers.
[0011] Comparing to the system disclosed in the prior art, an
advantage of the system of the present invention which has a 3-D
stacked architecture is that it has a smaller footprint and may
treat larger scale semiconductor wafers with great efficiency to
provide high throughput because additional footprint took by some
processing cells such as plating cells is saved, and another
advantage of the system of the present invention is that it could
be expandable to accommodate newly-added processing units without
overmuch increased footprint because the newly-added processing
units could be disposed on the corresponding layer or layers other
than on only one layer as in the prior art, and yet another
advantage of the system of the present invention is that it can be
serviced and maintained conveniently because the wafer holder
assemblies are disposed on the top of the mainframe, eliminating
the need of bulky supporting posts which greatly limit tool
accessibility, and they can be moved to the corners of the
mainframe during user intervention.
[0012] The further characteristic of said electrochemical
deposition system according to the present invention is that the
thermal treatment chamber comprises a heating plate and a heating
fluid dispenser for double-side heating the semiconductor wafer, a
cooling plate and a cooling fluid dispenser for double-side cooling
the semiconductor wafer, at least two wafer holders for receiving
the semiconductor wafer and transferring the semiconductor wafer
from the heating plate to the cooling plate, and at least two
actuators for controlling the movement of the wafer holders. As a
result, the system in accordance with the present invention may
provide a uniform post electroplating thermal treatment process to
improve the electrical and physical properties of the deposited
metal films on semiconductor wafers by double-side thermal treating
of the wafer, and the thermal treatment chamber could thermally
treat multiple wafers simultaneously so that the number of thermal
treatment chambers in the mainframe is reduced and throughput of
the system of the present invention is increased. And the
processing wafer is transferred onto the heating plate in the
thermal treatment chamber by the mainframe robot before the
beginning of the process and transferred out from the cooling plate
in the thermal treatment chamber by the front robot after the
process ends. No mainframe/factory-interface hand-off station is
needed post processing, so that the robot handoff points are
reduced and the transfer efficiency of the system is improved.
[0013] The still further characteristic of said electrochemical
deposition system according to the present invention is that it may
also comprise a vapor phase pre-wet device connected to a vapor
generating and delivery system to realize liquid molecules
adsorption onto the front surface of a semiconductor wafer that
will be processed in the electroplating cell from vapor phase. The
adsorbed, or condensed liquid molecules form a thin pre-wetting
layer on the front surface of the semiconductor wafer before the
semiconductor wafer bearing such a film is put into contact to the
electrolyte solution. As a result, the system in accordance with
the present invention could provide the reliable process to deposit
copper films in ultra-small features on the semiconductor wafer
surface without voids caused by incomplete wetting.
[0014] While novel features of the invention are set forth in the
preceding, the invention, both as to organization and content, can
be further understood and appreciated, along with other objects and
features thereof, from the following detailed description and
examples when taken in conjunction with the attached drawings.
DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a schematically perspective view of an
electrochemical deposition system of the invention.
[0016] FIG. 2 is a side view of an electrochemical deposition
system of the invention.
[0017] FIG. 3 is a schematically perspective view of an
electroplating cell of an electrochemical deposition system of the
invention.
[0018] FIG. 4 is a schematically perspective view of a wafer holder
assembly of an electrochemical deposition system of the
invention.
[0019] FIG. 5 is a schematically perspective view of thermal
treatment module of an electrochemical deposition system of the
invention.
[0020] FIG. 6 is a schematic diagram of the fluid supply system in
the electrochemical deposition system of the invention.
[0021] FIG. 7 is a schematic diagram of the electrical control
system in the electrochemical deposition system of the
invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0022] With reference to FIG. 1-FIG. 2, the electrochemical
deposition system in accordance with the present invention
comprises a factory interface 10 and a mainframe 11. The factory
interface includes a plurality of wafer load ports 101, a wafer
transfer robot 102, and a wafer aligner 191, all enclosed in a
class 1 mini-environment. The mainframe comprises a mainframe
transfer robot 106, a plurality of electroplating cells 107, a
plurality of cleaning cells 108, a plurality of thermal treatment
chambers 104 and at least one vapor pre-wet module 110. The
electroplating cells 107 and the cleaning cells 108 are positioned
within the first layer and second layer of the mainframe 11
separately, with one electroplating cell 107 stacked over one
cleaning cell 108. The thermal treatment chambers 104 are
positioned in the mainframe 11 and connected to the factory
interface 10. Furthermore, the system comprised a delivery cassette
103 and a temporary storage cassette 112 which are attached to the
factory interface 10 and located over the thermal treatment
chambers 104. The delivery cassette 103 is used for transportation
of a semiconductor wafer from the factory interface 10 into the
mainframe 11. And the temporary storage cassette 112 is used to
store affected wafers in case of excursion taking place to any one
of the process chambers. In this case the mainframe transfer robot
106 will place wafers that are partially processed in the whole
electroplating process into the temporary storage cassettes 112 for
further treatment. The system further comprises a fluid
distribution system that is connected to the process cells and
provides plating electrolyte to the plating cells and chemical
solutions to the cleaning cells. The system further comprises a gas
mixing and delivery system which is connect to the thermal
treatment chambers and provides mixed process gas to the thermal
treatment chambers.
[0023] The factory interface 10 includes a plurality of load ports
101 for receiving and positioning wafer pods 192, a front interface
robot 102 and at least one wafer aligner 191. In the present
embodiment, the factory interface 10 comprises three load ports 101
and one wafer aligner 191. The pod 192, which preferably is the
industrial wafer FOUP (front opening unified pod) accommodating
multiple wafers, is transferred and disposed onto one of the load
ports 101 after previous treatment of process of the wafers is
ended, such as physical vapor deposition, chemical vapor
deposition, or atomic layer deposition of a thin conductive layer
on the wafer surface before the electro-chemical plating process.
The front interface robot 102 is a typical transfer robot commonly
known to the persons skilled in the field which comprises one or
two arms.
[0024] All process modules are located inside the mainframe.
Referring to FIG. 2 again, each of the electroplating cells 107
locates vertically over one of the cleaning cells 108. In the
present embodiment, the mainframe 11 comprises four electroplating
cells 107 and four cleaning cells 108 corresponding to the number
of loading ports 101. It should be understood that the number of
the electroplating cells 107 in the mainframe 11 of the
chemical-electroplating system in accordance with the invention are
not limited by the exemplary embodiment. The person skilled in the
field could increase or decrease the number of the cells according
to the desired throughput of the system. And it should be noticed
that stacked plating cells 107 and cleaning cells 108 save places
for the mainframe 11 and reduce the footprint of the
electrochemical deposition system. And it will be noted in the
following specification that the 3-D architecture of the system
with the plating cells 107 stacked over the cleaning cells 108 are
expandable to accommodate newly-added processing units without
overmuch increased footprint.
[0025] The mainframe 11 also comprises pluralities of wafer holder
assemblies 105, each of which is disposed above one of the
electroplating cells 107 and mounted on the top of the mainframe
11. In this embodiment of the electrochemical deposition system in
accordance with this present invention, the mainframe 11 comprises
four wafer holder assemblies 105 corresponding to the number of the
electroplating cell 107.
[0026] Referring to FIG. 4, the wafer holder assembly 105 comprises
a semiconductor wafer chuck assembly, which further comprises a
semiconductor wafer chuck 511 and a cathode contact (not shown),
and an actuator. The actuator may comprise step motors 521, 523 and
servo motor 525. The cathode contact may comprise a plurality of
soft stainless steel coil springs to maintain a uniform cross
section profile which improves electrical contact to the wafer and
reduces damage to the underlying film stack caused by compressive
stress from mechanical contact. The wafer chuck may comprise a
bottom section and a top section and the wafer is held between the
bottom section and the top section, thereby the wafer chuck
assembly suitably being configured to open, close and rotate the
wafer chuck for inserting, removing and rotating the wafer, and the
cathode contact being disposed between the bottom section and the
top section of the wafer chuck and could electrically contact to
the wafer front-side when the wafer chuck is closed by the actuator
before the electro-chemical plating process starts. Electrical
information from contact locations is monitored and fed back to the
control system. Additionally, the wafer holder assembly 105 could
be moved to the corner of the mainframe 11 for performance
maintenance. The semiconductor wafer could be held by the chuck 511
and moved along Z axis and rotated along the X axis and Z axis
respectively with the chuck 511 drove by the step motors 521, 523
and servo motor 525 of the actuator. For a more detailed
description of wafer chuck component which comprises a wafer chuck
and a cathode contact, see U.S. Pat. No. 6,495,007, entitled
"Methods and apparatus for holding and positioning semiconductor
wafer during electropolishing and/or electroplating of the
workpieces", the entire content of which is incorporated herein by
reference. In present invention, the entire wafer holder assembly
is supported by the mounting arm 527 which connects the wafer
holder assembly 105 to the top of the mainframe. It should be noted
that the configuration of wafer holder assembly 105 being disposed
on the top of the mainframe strengthens reachability of the
mainframe transfer robot 106 to the wafer holder assemblies and the
plating cells and saves spaces due to needless of supporting
post.
[0027] The mainframe 11 also comprises a vapor phase pre-wet device
which may be integrated on the wafer holder assembly 105 or be an
independent module (as shown in drawing). This pre-wet device is
connected to a vapor generating system and provides liquid vapor to
front surface of a semiconductor wafer for posing an ultra-thin
pre-wetting layer on the front surface to improve the wetting
performance during electroplating process. Pre-wetting by liquid
vapor can wet very small features, such as vias and trenches,
completely and does not cause appreciable dilution to the plating
electrolyte. Therefore the system of the present invention will
satisfy the needs to eliminate any incomplete wetting-related
defects brought about by the increase of circuit density in
ULSI.
[0028] Referring to FIG. 3, in the present embodiment, the
electroplating cell 107 comprises an electrolyte chamber 700. The
electrolyte chamber 700 comprises a plurality of annular electrodes
711 and a plurality of annular insulating walls 713 which separate
the whole electrolyte chamber 700 into a plurality of independent
regions, each of which containing a single annular electrode 711.
The electrode 711 are charged by a plurality of power supplies (not
shown) respectively by applying different waveforms and turning on
or off in different sequence or at different time during the
electroplating process.
[0029] For a more detailed description of the said electrolyte
chamber, also see U.S. Pat. No. 6,495,007, entitled "Methods and
apparatus for holding and positioning semiconductor wafer during
electropolishing and/or electroplating of the workpieces", the
entire content of which is incorporated herein by reference.
[0030] However, the electrolyte chamber 700 in the deposition
system according to the present invention have some difference with
the said electrolyte chamber in the prior art. The electrolyte
chamber 700 in the deposition system according to the present
invention is separated into a lower cell body 701 which receives
low cell feed electrolyte and an upper cell body 702 which receives
upper cell feed electrolyte by a bubble coalescence assembly
720.
[0031] An inlet and an outlet connected to each independent region
of the lower cell body 701 of the electrolyte chamber 700.
Electrolyte is pumped into each independent region of the
electrolyte chamber 700 by a pump from an electrolyte tank (which
will be described in details in the following passage) through the
inlet and then flows out through the outlet and finally returns to
said electrolyte tank to realize an independent electrolyte
circulation in each region of the lower cell 701 body of the
electrolyte chamber 700.
[0032] For each region of the upper cell body 702 there is an
electrolyte inlet which is controlled by a LMFC (Liquid Mass Flow
Controller) respectively to each separate region so that the
electrolyte flow rate in each region of the upper cell body 702 to
surface of a processing wafer can be controlled independently. The
LMFCs are acid and corrosion resistant. Both the lower cell body
701 and the upper cell body 702 are made of or coated with
electrical isolative and acid and corrosion resistant materials,
such as PVC or PVDF.
[0033] The bubble coalescence assembly 720 comprises a cone-shape
frame having pluralities of V-shape grooves and a porous membrane
attached closely on the cone-shape frame. A tube is disposed at the
top of the bubble coalescence assembly 720 which is connected to
the outside of the electroplating cell 107. Bubbles generated at
the electrodes 713 during electroplating will first coalesce in
V-shaped grooves and move upward to the top and then exit the
chamber through the said tube.
[0034] The cleaning cell 108 comprises a cell body having a window
for transferring semiconductor wafer into or out of the cleaning
cell 108 and a wafer holding part disposed at the center of the
cell body which could be rotated by an actuator disposed at the
bottom of the cleaning cell 108 with a speed of 10 to 4000 rpm. The
wafer holding part comprises 3 pins with a small angled step at the
top of each pin which positions the wafer within the cleaning cell
108 and a mechanical chuck disposed on each pin which could be
activated by spinning. And when the wafer holding part spins, the
mechanical chuck closes and holds the wafer tightly to prevent
relative motion between the semiconductor wafer and the pins; when
the wafer holding part stops spinning, the mechanical chuck opens
and the wafer could be pick up by the mainframe transfer robot.
[0035] The cleaning cell 108 is configured with one front side
nozzle, one backside nozzles, and one movable nozzle. The front
side nozzle which is disposed on and extends from the upper portion
of the cell body of the cleaning cell 108 provides DI water to the
front surface of a semiconductor wafer. The backside nozzle which
is disposed on and extends from the lower portion of cell body of
the cleaning cell 108 provides DI water to the backside of the
semiconductor wafer. The movable nozzle which is disposed on the
central section of the cell body of the cleaning cell 108 and can
radially move to the edge of a processing wafer provides mixed acid
and dioxide to the edge bevel of the semiconductor wafer while
working and moves away from the center of body of the cleaning cell
during the semiconductor wafer transfer. The movement of the
movable nozzle is controlled by an actuator. The cleaning cell 108
also comprises a lid disposed at the top of the body which prevents
fluid splashing out of the cleaning cell and contaminating the
parts of the present system. For more detailed description of the
said cleaning cell 108, see WO 03/087436, entitled
"Electropolishing and/or electroplating apparatus and methods", the
entire content of which is incorporated herein by reference.
[0036] The mainframe 11 also comprises a fluid distribution system
which comprises a electrolyte tank 109 located at the bottom part
of the mainframe 11, which supplies plating electrolyte to each
electroplating cell 107. With reference now to FIG. 6, the
electrolyte tank 109 is separated into a lower cell electrolyte
tank 191 and a upper cell electrolyte tank 192. The lower cell
electrolyte tank 191 is fluidly connected to the lower cell bodies
of the electroplating cells 107 to provide lower cell feed
electrolyte to the electroplating cells 107, and the upper cell
electrolyte tank 192 is fluidly connected to the upper cell body of
the electroplating cells 107 to provide upper cell feed electrolyte
to the upper cell bodies of the electroplating cells 107 for
electroplating. The lower cell electrolyte tank 191 and the upper
cell electrolyte tank 192 is connected to electroplating cell 107
with an electrolyte supply line 311 and 321 through pump 313 and
valves respectively which comprise a two-way valve 315, a check
valve 316 and control valve 312. Preferably, the electrolyte line
connecting the maintank 109 to the electroplating cell 107 is
coupled with a filter 317 to filter the impurities and a flow-meter
314 with analog output to monitor the flow rate. The maintank 109
is configured with a temperature sensor and a chiller to maintain
the temperature of the electrolyte both in the lower cell
electrolyte tank and the upper cell electrolyte tank at a fixed
temperature. The lower cell electrolyte tank and upper cell
electrolyte tank also respectively connects to a metrology tool 351
by two additional pipes 321 to provide a sample of the electrolyte
to the metrology tool 351 which may monitor the concentration of
components of the electrolyte in the lower cell electrolyte tank
and upper cell electrolyte tank.
[0037] The fluid distribution system also comprises a chemical tank
330 where acid and dioxide are mixed homogeneously and then are
provided to the movable nozzle in cleaning cells 108. The chemical
tank 330 connects to the chemical metrology tool 351 through a pipe
352 to provide a sample of the mixed chemicals made from the acid
and dioxide to the metrology tool 351 to monitor the concentration
of the components of the mixed chemicals. The mixed chemicals in
the chemical tank 330 is transferred to the movable nozzle of the
cleaning cell 108 through pump 353 and serial valves which
preferably include a two-way manual valve 355, control valve 352
and two-way pneumatic valve 359 for removing the deposited metal at
the edge bevel of the wafer after electroplating. Preferably, the
pipe connected the chemical tank 330 and the cleaning cell 108
interconnects a filter 357 to filter the impurities and a
flow-meter 354 with analog output to monitor the flow rate.
[0038] The system in accordance with the present invention also
comprises a dosing system 361. The dosing system 361 electrically
connected to an electrical control module (which will be described
in details in the following context) will dose the required amount
of metal ions or organic additives to lower cell electrolyte tank
and upper cell electrolyte tank of the electrolyte tank 109
depending on algorithm provided by operator and the analyzing
results from the chemical analyzing tool 351 to keep the stable
electro-deposition performance of the electrolyte and the edge
bevel removal performance of the mixed chemicals.
[0039] Referring to FIG. 5, in the present embodiment, there are
two thermal treatment chambers 104 which are positioned in parallel
in the mainframe 11 and connected to the factory interface 10. The
thermal treatment chamber 104 preferably comprises a rectangle
shape body with two windows, one window facing against the
mainframe 11 which is the heating cell window 421 and the other
window facing against the factory interface 10 which is the cooling
cell window 523. The thermal treatment chamber 104 also comprises a
heating plate 411 disposed within the body of thermal treatment
chamber 104 which is near the heating cell window 421, a cooling
plate 413 disposed within the body which is near the cooling cell
window 423, and two wafer holders 431,433 respectively disposed at
opposite sides of the heating plate 411 or cooling plate 413. The
wafer holders 431,433 are used for receiving a semiconductor wafer
from the mainframe transfer robot 106, loading the wafer onto the
heating plate 411 or cooling plate 413, transferring the wafer from
heating plate 411 to cooling plate 413 and transferring the wafer
to the front interface robot 102. The wafer holder 411 or 413
comprises an arm 439 which is connected to an actuator 438
comprising two step or servo motors, and is configured with a
supporting ring 437 with a plurality of support fingers thereon.
The wafer holder 431 of the thermal treatment chamber 104 may
rotates and moves vertically with the control of the actuator 438.
The thermal treatment chamber 104 also comprises a lid 441 with two
fluid distribution parts 448,449 on the lid 441 and a fluid line
443 fluidly connected with the fluid distribution parts 448,449.
Each fluid distribution part 449 is positioned over one of heating
plate 411 and the cooling plate 413 to provide required fluid into
the thermal treatment chamber, such as mixture of N.sub.2 and
H.sub.2. The distribution part 449 over the heating plate 411
provides hot fluid to the front surface of the wafer to realize a
double side heating of the wafer, with the heating plate heating
the backside of the wafer. The distribution part 448 over the
cooling plate 413 provides cool fluid to the front side of the
wafer to realize a double side cooling, with the cooling plate
cooling the backside of the wafer. This double-side thermal
treatment mechanism provides a uniform thermal treatment process
and reduces the thermal stress induced bowing of the wafer, and,
together with the ability of thermal treating multiple wafers in
the thermal treatment chamber, greatly increases the efficiency and
throughput of the thermal treatment chamber.
[0040] The mainframe 11 further comprises an electrical control
module at the back of the mainframe. The block diagram of the
electrical control module is shown in the FIG. 4. The electrical
control module typically comprises a host computer with a user
interface in connection with the module, robot control system,
motor driver, I/O interface chassis and plating power control
board. The host computer is the key control equipment of the
electrical control module, which provides all the I/O ports, RS232
ports and the motion control board. Host computer transmits the
signals via I/O interface chassis to every process cell which needs
the control signal for flow control, such as the electrolyte flow
control of the electroplating cell and DI water or acid flow
control of nozzles of the cleaning cell. Plating power control
board, which electrically connected to the I/O interface chassis
and the electroplating cell 107, provides adjustable high
voltage/current for the high power consumptions for the
electroplating cell 107. The host computer transmits all signals of
the control parameters via robot control system to control the
mainframe transfer robot and front interface robot. However, robot
control system may be a stand-alone computer which communicates
with host computer via RS232 port, so the robot control system
still could control the mainframe transfer robot and the front
interface robot without the host computer. The motor driver, which
electrically connects to the host computer and servo/step motors of
the electroplating cell, cleaning cell and the thermal treatment
chamber respectively, transfers the control signal from the motion
control board of host computer to servo/step motors of the thermal
treatment chamber, the clean cell or the electroplating cell, and
the encoding signal that servo/step motors feedback to host
computer.
[0041] It should be noted that the whole electrochemical deposition
process should be performed in a clean environment, so the system
according to the present invention is preferably enclosed by
panels. There are transparent windows configured on part of the
panels so that the electrochemical plating process could be under
monitoring by the operator. The panels are removable or configured
to provide openings for convenience of performance maintenance.
[0042] In operation, the front interface robot 102 transfers a
wafer from the pods 192 to the wafer aligner 191. Then the wafer
received by the wafer aligner 191 is rotated to a prearranged
orientation by the wafer aligner 191 to facilitate the wafer to be
precisely controlled in the next processes. After wafer alignment,
the front interface robot 102 will transfer the wafer into wafer
delivery cassettes 103 for further transportation into the
mainframe 11.
[0043] The mainframe transfer robot 106 transfers a semiconductor
wafer from the wafer delivery cassette 103 into wafer holder
assembly 105 or from an electroplating cell 107 to a cleaning cell
108 of the mainframe or from the cleaning cell 108 into the thermal
treatment chamber 104. The robot 106 is a transfer robot commonly
known to persons skilled in the relevant field of technology, which
preferably comprises a plurality of transfer arms. In this present
embodiment, the mainframe transfer robot 106 comprises two transfer
arms, which can be operable independently. The mainframe transfer
robot 106 may rotate around a Z-axis shown in FIG. 2 and move up
and down vertically. The two robot arms of the mainframe transfer
robot 106 may be controlled to extend and retract for transferring
semiconductor wafers into or out of the electroplating cells 107 or
the cleaning cells 108, also to flip the semiconductor wafers to
meet the requirements of different processes, for example,
semiconductor wafers should be disposed downwardly in the
electroplating process, but upwardly in the cleaning process.
[0044] For the process, firstly, the wafer holder assembly 105
stays at a receiving position and the chuck 511 of the wafer holder
assembly 105 is at an open status. The mainframe transfer robot 106
picks up a semiconductor wafer from the delivery cassette 103 which
disposed in between the mainframe 106 and the factory interface 10,
flips it face downward and transfers it to the vapor phase pre-wet
device, where the pre-wet device is an independent module as shown
in the figure. The pre-wet device splashes vapor to the front
surface of the wafer and forms a thin layer of pre-wet liquid on
it. Then the mainframe robot transfers the wafer into the chuck of
wafer holder assembly 105, and positions it on the cathode contact
in the wafer holder assembly. After the arms of the mainframe
transfer robot 106 retracts out of the wafer holder assembly 105,
the chuck of the wafer holder assembly 105 closes and holds the
semiconductor wafer in tight contact with the cathode spring. And
the backside of the semiconductor wafer is well sealed to prevent
the backside of the wafer in contact with electrolyte during
plating. The servo motor 525 begins rotating and thereby wafer
holder assembly 105 starts spinning the wafer. The step motor 523
rotates to carry the wafer holder assembly 105 to a certain angle
relative to the z direction and then step motor 521 moves the wafer
holder assembly 105 along the z direction to a pre-process position
to make the edge of the chuck 511 just over the liquid level of
electroplating cell 107. Thereafter motor 523 starts rotating the
wafer holder assembly 105 back to vertical position, and brings the
wafer holder assembly 105 into the electroplating cell 107 and
thereby makes the front surface of the semiconductor wafer in
contact with the electrolyte in the upper cell body 702 of the
electroplating cell 700. After that, the electroplating process
starts. By controlling the waveform, working sequence and time of
multiple anodes and electrolyte flow rate, a uniform metal film
could be deposited on the semiconductor wafer. For more detailed
electroplating process, see U.S. Pat. No. 6,391,166, entitled
"plating apparatus and methods", and the entire content of which is
incorporated herein by reference.
[0045] In another embodiment, the vapor phase pre-wet device is
integrated on the wafer holder assembly. In process the mainframe
robot picks up the wafer from the delivery cassette and transfers
it into the wafer holder assembly. Before the wafer holder assembly
carries the wafer into the electrolyte, the pre-wet device moves in
and slashes vapor onto the wafer surface. When the pre-wet process
is done, the wafer holder assembly then carries the wafer into the
electrolyte and the same electroplating process is carried out as
above.
[0046] After the electroplating process is completed, the wafer
holder assembly 105 moves up and brings the semiconductor wafer out
of the electrolyte of the electroplating cell 107. When the wafer
holder assembly 105 moves to a spin position, it rotates with the
processed wafer with a large rpm to remove the residual electrolyte
on the wafer surface. Then the wafer holder assembly 105 moves to
the receiving position and the chuck 511 opens. The arm of the
mainframe transfer robot 106 extends into the wafer holder assembly
105, transfers the semiconductor wafer out and flips it to face
upward.
[0047] Then the mainframe transfer robot 106 moves down until it
reaches the level of the window of the cleaning cell 108, the arms
of mainframe transfer robot 106 extends and transfers the
semiconductor wafer into the cleaning cell 108. When the
semiconductor wafer is transferred into the cleaning cell 108, the
arm of mainframe transfer robot 106 moves down a little bit, places
the semiconductor wafer on the three pins of the cleaning cell 108
and then moves out. The wafer holding part of the cleaning cell 108
which holds the wafer with three pins starts rotating controlled by
the actuator. The mechanical chuck on the pins turns on and holds
the semiconductor wafer tightly to prevent relative motion. Then
the front surface nozzle of the cleaning cell turns on and splashes
DI water from DI water facility onto the front side of the
semiconductor wafer to pre-rinse and remove residual plating
electrolyte. After the pre-rinse, the movable nozzle of the
cleaning cell moves to the edge of the semiconductor wafer and
splashes mixed chemicals from the chemical tank onto the edge bevel
of the semiconductor wafer to etch off the deposited metal film on
the edge bevel. The wafer holding part of the cleaning cell 108
spins with a large rpm to confine the chemicals at a narrow range
along the edge of the wafer to prevent etching of the deposited
metal film in the inner area. When the metal film at the bevel is
completely removed, the movable nozzle moves away from the center
of the cleaning cell and both front and back face nozzles turn on
and splash DI water on both sides of the semiconductor wafer to
rinse off the residual chemicals from etching. When the cleaning
process is completed, the wafer holding part stops spinning and the
mechanical chuck opens. The mainframe transfer robot 106 extends
into the cleaning cell 108, picks up the semiconductor wafer and
transfers it out of the cleaning cell 108.
[0048] When the electroplating and cleaning process of a wafer
(first wafer) is ended, the mainframe transfer robot 106 will
transfer the first wafer into the thermal treatment chamber 104
through the heating cell window 421 and place it on the first wafer
holder 433. While the arms of the mainframe transfer robot 106 move
out of the thermal treatment chamber 104, the first wafer holder
433 moves down to a pre-heating position to pre-heat the first
wafer for a scheduled time. After the pre-heating process is ended,
the first wafer holder 433 moves down and positions the wafer onto
the heating plate 411 such that the wafer is in contact with the
heating plate 411 and heated for a scheduled time. Once heating
process of the first wafer is ended, the first wafer holder 433
moves up and transfers the wafer onto the cooling plate 413 for
cooling process. And it should be noted that the heating plate 411
is free now. While the first wafer is in cooling process, another
wafer (second wafer) which has been treated with the electroplating
and cleaning process is transferred into the thermal treatment
chamber 104 by the mainframe transfer robot 106 and received by the
second wafer holder 431 and starts pre-heating and heating process.
Thus the thermal treatment chamber 104 does thermal treatment for
two wafers simultaneously. When cooling process of the first wafer
is ended, the first wafer holder 433 moves up and brings it to a
transfer position and the front interface robot 102 extends into
and transfers semiconductor it out of the thermal treatment chamber
104. And the cooling plate 413 is free now. After heating process
of the second wafer is ended, the second wafer holder 431 transfers
it onto the cooling plate 413 for cooling process. While the second
wafer is in cooling process, another wafer (third wafer) is
transferred into the thermal treatment chamber 104, received by the
first wafer holder 433 and is treated with the same processes
(pre-heating, heating, and cooling process). The process performed
in the thermal treatment chamber 104 described above depends on the
assumption that the time for heating is longer than that for
cooling. If the time for cooling is longer than that for heating,
the difference in the process is that, when the first wafer has
been heated on the heating plate 411 and is transferred to the
cooling plate 413, the second wafer will not be transferred into
the thermal treatment chamber 104 immediately until the remaining
cooling time for the first wafer is smaller than the heating time.
When the thermal treatment process of a wafer is ended, the wafer
is transferred out of the thermal treatment chamber 104 through the
cooling cell window 423 and placed into the pod 192 by the front
interface robot 102 for the next manufacture step, such as chemical
mechanical polishing.
[0049] While the foregoing is directed to the preferred embodiment
of the present invention, other and further embodiments of the
invention may be devised with out departing from the basic scope
thereof. The scope of the invention is determined by the claims
that follow.
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