U.S. patent application number 14/610017 was filed with the patent office on 2016-08-04 for electroplating apparatus and method.
The applicant listed for this patent is TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.. Invention is credited to YEN-YU CHEN, JUI-MU CHO, CHEN-HSIN FU, YI-HU LO, YUNG DI SHEN, CHIH-MING YEH, WEI ZHANG.
Application Number | 20160222537 14/610017 |
Document ID | / |
Family ID | 56552890 |
Filed Date | 2016-08-04 |
United States Patent
Application |
20160222537 |
Kind Code |
A1 |
SHEN; YUNG DI ; et
al. |
August 4, 2016 |
ELECTROPLATING APPARATUS AND METHOD
Abstract
An apparatus and a method for plating a substrate are provided.
The apparatus includes: an electroplating cell for containing an
electroplating solution; a substrate holder for holding a substrate
in the electroplating solution; a rotation driver coupled to the
substrate holder and configured to rotate the substrate holder; a
power distribution assembly coupled to the rotation driver; an
anode disposed within the electroplating cell; a power supply unit
electrically coupled between the anode and the power distribution
assembly, thereby forming an electric loop; and a current
regulating member for providing a predetermined impedance value for
the electric loop, wherein a voltage provided by the power supply
unit causes an electric current to flow through the electric loop,
and the predetermined impedance is such selected that the variation
of the electric current is kept within a smaller range compared to
that measured in the absence of the current regulating member.
Inventors: |
SHEN; YUNG DI; (CHANGHUA
COUNTY, TW) ; FU; CHEN-HSIN; (TAICHUNG CITY, TW)
; YEH; CHIH-MING; (TAICHUNG CITY, TW) ; LO;
YI-HU; (TAICHUNG CITY, TW) ; CHO; JUI-MU;
(HSINCHU COUNTY, TW) ; CHEN; YEN-YU; (TAICHUNG
CITY, TW) ; ZHANG; WEI; (HSINCHU COUNTY, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD. |
HSINCHU |
|
TW |
|
|
Family ID: |
56552890 |
Appl. No.: |
14/610017 |
Filed: |
January 30, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C25D 7/123 20130101;
C25D 17/10 20130101; C25D 17/06 20130101; C25D 5/48 20130101; C25D
21/12 20130101; C25D 3/38 20130101; C25D 5/04 20130101; C25D 17/001
20130101 |
International
Class: |
C25D 7/12 20060101
C25D007/12; C25D 5/22 20060101 C25D005/22; C25D 17/10 20060101
C25D017/10; C25D 21/10 20060101 C25D021/10; C25D 17/00 20060101
C25D017/00 |
Claims
1. An electroplating apparatus for electrochemically plating a
substrate, comprising: an electroplating cell for containing an
electroplating solution; a substrate holder for holding a substrate
in the electroplating solution; a rotation driver electrically
coupled to the substrate holder and configured to rotate the
substrate holder; a power distribution assembly electrically
coupled to the rotation driver; an anode disposed within the
electroplating cell, the anode being immersed in the electroplating
solution; a power supply unit electrically coupled between the
anode and the power distribution assembly, thereby forming an
electric loop; and a current regulating member for providing a
predetermined impedance value for the electric loop, wherein a
voltage provided by the power supply unit causes an electric
current to flow through the electric loop, and the predetermined
impedance is such selected that the variation of the electric
current flowing through the electric loop is kept within a smaller
range compared to that measured in the absence of the current
regulating member.
2. The electroplating apparatus of claim 1, wherein the anode is
made of gold, zinc, nickel, silver, copper or nickel.
3. The electroplating apparatus of claim 1, wherein the rotation
driver comprises a rotatable spindle and a slip ring assembly.
4. The electroplating apparatus of claim 1, wherein the power
supply unit comprises a DC power supply unit.
5. The electroplating apparatus of claim 1, wherein the current
regulating member is arranged on the electric loop and is not
disposed in the electroplating cell.
6. The electroplating apparatus of claim 1, wherein the
predetermined impedance value ranges from about 0.02 m.OMEGA. to
about 20.OMEGA..
7. The electroplating apparatus of claim 1, wherein the
predetermined impedance value ranges from about 0.05 m.OMEGA. to
about 5.OMEGA..
8. The electroplating apparatus of claim 1, wherein the
predetermined impedance value ranges from about 0.1 m.OMEGA. to
about 1.OMEGA..
9. The electroplating apparatus of claim 1, wherein the impedance
of the electric loop ranges from 1.OMEGA. to 50.OMEGA..
10. An electroplating apparatus for electrochemically plating a
substrate, comprising: an electroplating cell for containing an
electroplating solution; a substrate holder for holding a substrate
in the electroplating solution; a rotation driver electrically
coupled to the substrate holder and configured to rotate the
substrate holder; an anode disposed within the electroplating cell,
the anode being immersed in the electroplating solution, wherein a
voltage applied across the rotation driver and the anode causes an
electric current to flow from the rotation driver to the anode; and
a current regulating member electrically coupled to the rotation
driver, wherein a predetermined impedance value of the current
regulating member is such selected that the variation in the
electric current is kept within a smaller range compared to that
measured in the absence of the current regulating member.
11. The electroplating apparatus of claim 10, wherein the substrate
holder comprises a clamshell-type substrate holder.
12. The electroplating apparatus of claim 12, wherein the
clamshell-type substrate holder comprises a cone member, a cup
member and a seal member.
13. An electroplating method for electrochemically plating a
substrate, comprising: immersing a substrate into an electroplating
solution; electrically coupling an anode to the electroplating
solution; forming an electric loop in which an electric current
flows from a power supply to the anode, the electroplating
solution, the substrate, and back to the power supply; and
providing a current regulating member with a predetermined
impedance value on the electric loop, wherein the predetermined
impedance is such selected that the variation of the electric
current flowing through the electric loop is kept within a smaller
range compared to that measured in the absence of the current
regulating member, wherein the flow of the electric current through
the electric loop causes the deposition of a conductive material
onto the substrate.
14. The method of claim 13, wherein the predetermined impedance
value ranges from about 0.1 m.OMEGA. to about 1.OMEGA..
15. The method of claim 13, wherein the operation of immersing the
substrate into the electroplating solution further comprises
rotating the substrate in the electroplating solution.
16. The method of claim 13, wherein the electroplating solution
comprises copper sulfate or copper cyanide.
17. The method of claim 13, wherein the electroplating solution
comprises at least one of a brightener, suppressor and leveler.
18. The method of claim 13, wherein an operation of forming
additional conductive layers is performed prior to immersing the
substrate into the electroplating solution.
19. The method of claim 18, wherein the conductive layers comprise
a barrier layer and a seed layer.
20. The method of claim 13 further comprising planarizing a plated
surface of the substrate by chemical mechanical polishing (CMP).
Description
FIELD
[0001] The present disclosure relates generally to a method and
apparatus for electrochemically plating a semiconductor
structure.
BACKGROUND
[0002] Semiconductor devices are electronic components that exploit
the electronic properties of semiconductor materials as well as
organic semiconductors. Semiconductor devices have replaced
thermionic devices (vacuum tubes) in most applications. They use
electronic conduction in the solid state as opposed to the gaseous
state or thermionic emission in a high vacuum. Semiconductor
devices are manufactured both as single discrete devices and as
integrated circuits (ICs), which consist of a number of devices
manufactured and interconnected on a single semiconductor
substrate, or wafer.
[0003] Semiconductor device fabrication is a multiple-step sequence
of photo lithographic and chemical processing steps during which
electronic circuits are gradually created on a wafer made of pure
semiconducting material. Silicon is almost always used, but various
compound semiconductors are used for specialized applications.
Among semiconductor fabrication processes, layer deposition
processes are utilized to form IC components. One of the most
frequently employed layer deposition process is the
electro-chemical plating (ECP) process, which deposits a layer of
conductive material onto a substrate by electrolytic
deposition.
[0004] A problem confronted by the conventional electroplating
apparatus is that the varying of physical properties, dimensional
conditions or other parameters associated with components in the
electric loop would result in a significant variation in the
electric current flowing through the electric loop, thus affecting
the plating quality and uniformity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Aspects of the present disclosure are best understood from
the following detailed description when read with the accompanying
figures. It is noted that, in accordance with the standard practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
[0006] FIG. 1 is a schematic diagram illustrating an electroplating
apparatus for electrochemically plating a substrate in an
electrochemical plating (ECP) process.
[0007] FIG. 2 is a schematic diagram illustrating an electroplating
apparatus for electrochemically plating a substrate in accordance
with one embodiment of the present disclosure.
[0008] FIG. 3 is a schematic diagram illustrating an electroplating
apparatus in accordance with one embodiment of the present
disclosure.
[0009] FIG. 4 is a cross-sectional view illustrating a substrate
holder and a rotation driver in accordance with one embodiment of
the present disclosure.
[0010] FIG. 5 is a cross-sectional view illustrating a substrate
holder and a rotation driver in accordance with one embodiment of
the present disclosure.
[0011] FIG. 6 is a schematic diagram illustrating an electroplating
apparatus for electrochemically plating a substrate.
[0012] FIG. 7 is a schematic diagram illustrating an electroplating
apparatus for electrochemically plating a substrate in accordance
with one embodiment of the present disclosure.
[0013] FIG. 8 is a flowchart of a method for electrochemically
plating a substrate.
DETAILED DESCRIPTION
[0014] The manufacturing and use of the embodiments of the present
disclosure are discussed in details below. It should be
appreciated, however, that the embodiments provide many applicable
inventive concepts that can be embodied in a wide variety of
specific contexts. It is to be understood that the following
disclosure provides many different embodiments or examples for
implementing different features of various embodiments. Specific
examples of components and arrangements are described below to
simplify the present disclosure. These are, of course, merely
examples and are not intended to be limiting.
[0015] Embodiments, or examples, illustrated in the drawings are
disclosed below using specific language. It will nevertheless be
understood that the embodiments and examples are not intended to be
limiting. Any alterations and modifications in the disclosed
embodiments, and any further applications of the principles
disclosed in this document are contemplated as would normally occur
to one of ordinary skill in the pertinent art.
[0016] Further, it is understood that several processing steps
(operations) and/or features of a device may be only briefly
described. Also, additional processing steps and/or features can be
added, and certain of the following processing steps and/or
features can be removed or changed while still implementing the
claims. Thus, the following description should be understood to
represent examples only, and are not intended to suggest that one
or more steps or features is required.
[0017] In addition, the present disclosure may repeat reference
numerals and/or letters in the various examples. This repetition is
for the purpose of simplicity and clarity and does not in itself
dictate a relationship between the various embodiments and/or
configurations discussed.
[0018] Further, spatially relative terms, such as "beneath,"
"below," "lower," "above," "upper" and the like, may be used herein
for ease of description to describe one element or feature's
relationship to another element(s) or feature(s) as illustrated in
the figures. The spatially relative terms are intended to encompass
different orientations of the device in use or operation in
addition to the orientation depicted in the figures. The apparatus
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
may likewise be interpreted accordingly.
[0019] Integrated chips (IC) are manufactured by subjecting a
semiconductor subject to multiple processing steps. Among these,
layer deposition processes are utilized to form IC components such
as polysilicon gate material and metal interconnect layers within a
cavity of a dielectric layer. Deposition processes include physical
vapor deposition (PVD), atomic layer deposition (ALD) and
electrochemical plating (ECP).
[0020] Electrochemical plating (ECP) processes deposit a layer of
conductive material onto a substrate by electrolytic deposition,
wherein a substrate is submerged into an electroplating solution
comprising ions of a material to be deposited. A DC voltage is
applied to the substrate, causing it to act as a cathode which
attracts cations of the electroplating solution, which reduce and
accumulate over the substrate to form a thin film onto the
substrate.
[0021] In reference to the drawings, FIG. 1 is a schematic diagram
illustrating an electroplating apparatus 100 for electrochemically
plating a substrate in an electrochemical plating (ECP) process.
The electroplating apparatus 100 comprises an electroplating cell
101, a substrate holder 103, a rotation driver, a power
distribution assembly 106 and an anode 107. The electroplating cell
101 serves as a container/vessel for containing an electroplating
solution 102. The substrate holder 103 is configured for holding a
substrate 104 in the electroplating solution 102. The rotation
driver 105 is configured to rotate the substrate holder 103 and is
electrically coupled to the substrate holder 103. The power
distribution assembly 106 is electrically coupled to the rotation
driver 105. In addition, the anode 107 is disposed within the
electroplating cell 101 (the anode 107 being immersed in the
electroplating solution 102). The electroplating apparatus 100
further comprises a power supply unit 108 that is electrically
coupled between the anode 107 and the power distribution assembly
106, thereby forming an electric loop (not shown). The power supply
unit 108 is configured to provide a voltage V (not shown) that
causes an electric current I.sub.1 to flow through the electric
loop. Namely the electric current I.sub.1 would flow from the power
supply unit 108 through the anode 107, the electroplating solution
102, the substrate 104, the substrate holder 103, the rotation
driver 105, the power distribution assembly 106 and back to the
power supply unit 108. The flow of the electric current I.sub.1
through the electric loop would cause the deposition of a
conductive material (not shown) of the electroplating solution 102
onto the substrate 104.
[0022] As is well known for a skilled person, regarding an
electrochemical plating (ECP) process, the plating quality and
uniformity depend on the stability and uniformity of current
distribution. Given that the voltage V provided by the power supply
unit 108 being a fixed value, the electric current I.sub.1 is
dependent on the total effective impedance of the electric loop,
which includes the effective impedance of the substrate 104, the
substrate holder 103, the rotation driver 105, the power
distribution assembly 106, the power supply unit 108, the anode
107, the conductive path of the electroplating solution 102
(staring from the anode 107 to the substrate 104) and the
conductive lines. Therefore, a problem confronted by the
conventional electroplating apparatus 100 is that the varying of
physical properties, dimensional conditions or other parameters
associated with components (e.g., the substrate 104) in the
electric loop would result in a significant variation in the
electric current I.sub.1 flowing through the electric loop, thus
affecting the plating quality and uniformity.
[0023] Furthermore, a significant variation in the electric current
flowing through the electric loop of an electroplating apparatus
would result in other problems in electroplating a semiconductor
substrate (or wafer). Generally an electroplating process performed
by an electroplating apparatus would not be carried out before
complete immersion of the substrate into the electroplating
solution. During a pre-plating step (which is defined as a time
period starting from the commencement of immersion to complete
immersion of the substrate into the electroplating solution), the
electric current would gradually rise to a peak electric current
value (as the resistance/impedance between the
substrate/electroplating solution interface gets smaller).
Accordingly, the detection of the peak electric current value can
be used as an indicator of complete immersion of the substrate into
the electroplating solution so as to facilitate following
electroplating operations. In view of the above, a significant
variation in the electric current flowing through the electric loop
(resulted from, e.g., wafer-to-wafer variation) would result in a
significant variation in the peak electric current value, which in
turn affects plating quality or reduces throughput.
[0024] To address the aforementioned problem that exists in the
conventional electroplating apparatus 100, an electroplating
apparatus with an additional current regulating member is proposed.
FIG. 2 is a schematic diagram illustrating an electroplating
apparatus 200 for electrochemically plating a substrate in
accordance with one embodiment of the present disclosure.
Similarly, the electroplating apparatus 200 comprises an
electroplating cell 101, a substrate holder 103, a rotation driver
105, a power distribution assembly 106, an anode 107, a power
supply unit 108 and a current regulating member 109. The
electroplating cell 101 contains an electroplating solution 102 and
the substrate holder 103 is configured holding a substrate 104. The
power supply unit 108 may be a DC power supply unit. According to
the arrangement shown in FIG. 2, the current regulating member 109
is electrically coupled between the rotation driver 105 and the
power distribution assembly 106. However, it should be noted that
the current regulating member 109 may be arranged at elsewhere on
the electric loop. For instance, in FIG. 3 (which is a schematic
diagram illustrating an electroplating apparatus 300 in accordance
with one embodiment of the present disclosure), the current
regulating member 109 is electrically coupled between the power
supply unit 108 and the anode 107. Alternatively, the current
regulating member 109 may be electrically coupled between the power
supply unit 108 and the power distribution assembly 106. Further
alternatively, the current regulating member 109 may be
electrically coupled between the substrate holder 103 and the
rotation driver 105. Note that the current regulating member 109
should not be disposed within the electroplating cell 101.
[0025] Referring back to FIG. 2, a voltage V provided by the power
supply unit 108 would cause an electric current I.sub.2 to flow
through the electric loop, wherein the electric current I.sub.2
would flow from the power supply unit 108 through the anode 107,
the electroplating solution 102, the substrate 104, the substrate
holder 103, the rotation driver 105, the current regulating member
109, the power distribution assembly 106 and back to the power
supply unit 108. The flow of the electric current I.sub.2 through
the electric loop would cause the deposition of a conductive
material of the electroplating solution 102 onto the substrate
104.
[0026] The current regulating member 109 serves to provide a
predetermined impedance value for the electric loop. The
predetermined impedance is such selected that the variation of the
electric current I.sub.2 flowing through the electric loop is kept
within a smaller range compared to the electric current I.sub.1
flowing through the electric loop (which is measured in the absence
of the current regulating member 109). The selection of the
predetermined impedance is based on the following two criteria: (1)
the larger impedance the current regulating member 109 has, the
variation of the electric current flowing through the electric loop
is more controllable; and (2) the larger impedance the current
regulating member 109 has, the greater amount of power it consumes.
Preferably, the predetermined impedance value ranges from 0.02
m.OMEGA. to 20.OMEGA.. More preferably, the predetermined impedance
value ranges from 0.05 m.OMEGA. to 5.OMEGA.. Yet more preferably,
the predetermined impedance value ranges from 0.1 m.OMEGA. to
1.OMEGA.. Most preferably, the predetermined impedance value is 50
m.OMEGA.. Note that the total impedance of the electric loop ranges
from 1.OMEGA. to 50.OMEGA..
[0027] In one embodiment, the substrate 104 is a semiconductor
wafer with conductive elements/features (e.g., conductive plugs,
conductive vias, conductive posts, filler materials or conductive
traces) provided on an active surface (plating surface) thereof. In
one embodiment, the substrate 104 may comprise logic devices,
eFlash device, memory device, microelectromechanical (MEMS)
devices, analog devices, CMOS devises, combinations of these, or
the like. The substrate 104 may comprise bulk silicon, doped or
undoped, or an active layer of a silicon-on-insulator (SOI)
substrate. Generally, an SOI substrate comprises a layer of a
semiconductor material such as silicon, germanium, silicon
germanium, SOI, silicon germanium on insulator (SGOI), or
combinations thereof. In one embodiment, the substrate 104 includes
multi-layered substrates, gradient substrates, hybrid orientation
substrates, any combinations thereof and/or the like, such that the
semiconductor package can accommodate more active and passive
components and circuits. In one embodiment, the electroplating
apparatus 200 is employed for electrochemically plating the
substrate 104 so as to form copper interconnects, patterns or
layers on semiconductor features previously arranged on the active
surface of the substrate 104.
[0028] In one embodiment, the conductive material that is to be
plated onto the substrate 104 may be a metal (such as gold, zinc
nickel, silver, copper or nickel), and the anode 107 may be made of
the same metal. Also, the electroplating solution 102 may include a
metal salt of the same metal. In one embodiment, the conductive
material that is to be deposited/plated onto the substrate 104 is
copper. Thus, the anode 107 may be made of copper. The
electroplating solution 102 may include a mixture of copper salt,
acid, water and various organic and inorganic additives that
improve the properties of the deposited copper. Suitable copper
salts for the electroplating solution 102 comprise copper sulfate,
copper cyanide, copper sulfamate, copper chloride, copper formate,
copper fluoride, copper nitrate, copper oxide, copper
fluorine-borate, copper trifluoroacetate, copper pyrophosphate and
copper methane sulfonate, or hydrates of any of the foregoing
compounds. The concentration of the copper salt used in the
electroplating solution 102 will vary depending on the particular
copper salt used. Various acids can be used in the electroplating
solution 102, comprising: sulfuric acid, methanesulfonic acid,
fluoroboric acid, hydrochloric acid, hydroiodic acid, nitric acid,
phosphoric acid and other suitable acids. The concentration of the
acid used will vary depending on the particular acid used in the
electroplating solution 102.
[0029] In one embodiment, the electroplating solution 102 is a
copper sulfate (CuSO.sub.4) solution. The substrate 104 and the
anode 107 are both immersed in the electroplating solution 102
(CuSO.sub.4 solution) containing one or more dissolved metal salts
as well as other ions that permit the flow of electricity. The
power supply unit 108 supplies an electric current to the anode
107, oxidizing the copper atoms that the anode 107 comprises and
allowing them to dissolve in the electroplating solution 102. At
the substrate 104 (cathode), the dissolved metal ions (cation
Cu.sup.2+) in the electroplating solution 102 are reduced to
metallic copper onto the substrate 104 by gaining two electrons. At
the anode 107, copper is oxidized at the anode to Cu.sup.2+ by
losing two electrons. The result is the transfer of copper from the
anode 107 to the substrate 104. The rate at which the anode 107 is
dissolved is equal to the rate at which the substrate 104 is
plated. In this manner, the ions in the electroplating solution 102
are continuously replenished by the anode 107.
[0030] The electroplating solution 102 may comprise additives that
improve certain electroplating characteristics of the
electroplating solution, improve the properties of the deposited
copper or accelerate the copper deposition rate. One of the key
functions of the additives is to level the deposit by suppressing
the electrodeposition rate at protruding areas in the surface of
the substrate 104 and/or by accelerating the electrodeposition rate
in recessed areas in the surface of the substrate 104. The
adsorption and inhibition may be further enhanced by the presence
of halogen ions.
[0031] Common additives for copper electroplating solution include
brighteners, suppressors and levelers. Brighteners are organic
molecules that tend to improve the specularity (or reflectivity) of
the copper deposit by reducing both surface roughness and
grain-size variation. Suitable brighteners include, for example,
organic sulfide compound, such as bis-(sodium
sulfopropyl)-disulfide, 3-mercapto-1-propanesulfonic acid sodium
salt, N-dimethyl-dithiocarbamyl propylsulfonic acid sodium salt and
3-S-isothiuronium propyl sulfonate, or mixtures of any of the
foregoing compounds. Suppressors are macromolecule deposition
inhibitors that tend to adsorb over the surface of the substrate
and reduce local deposition rates, increasing the deposition
uniformity. Levelers usually have ingredients with nitrogen
functional group and may be added to the electroplating solution at
a relatively low concentration. Traditional leveling involves the
diffusion or migration of strongly current suppressing species to
corners or edges of macroscopic objects which otherwise plate more
rapidly than desired due to electric field and solution mass
transfer effects. The levelers may be selected from the following
agents: a polyether surfactant, a non-ionic surfactant, a cationic
surfactant, an anionic surfactant, a block copolymer surfactant, a
polyethylene glycol surfactant, polyacrylic acid, a polyamine,
aminocarboxylic acid, hydrocarboxylic acid, citric acid, entprol,
edetic acid, tartaric acid, a quaternized polyamine, a
polyacrylamide, a cross-linked polyamide, a phenazine azo-dye, an
alkoxylated amine surfactant, polymer pyridine derivatives,
polyethyleneimine, polyethyleneimine ethanol, a polymer of
imidazoline and epichlorohydrine, benzylated polyamine polymer.
[0032] Another approach to achieve even deposition of the metal
ions (from the electroplating solution 102) onto the substrate 104
is to stir the electroplating solution 102 to flow to the substrate
104 with uniform flow velocity. A uniform flow velocity is
important during the electroplating process to provide even
deposition of the metal ions from the electroplating solution 102
onto the substrate 104. In one embodiment, the flow velocity of the
electroplating solution 102 toward the center of the plating
surface of the substrate 104 is controlled to be the same as the
flow velocity of the electroplating solution 102 toward the
peripheral region of the plating surface of the substrate 104.
Thus, the uniform flow velocity of the electroplating solution 102
(as it flows laterally across the plating surface of the substrate
104) results in uniform plating height. In addition, unevenness in
the plating thickness due to uneven flow velocity distribution of
the plating solution can be mitigated and uniform distribution of
the plating thickness can be achieved over the plating surface of
the substrate 104.
[0033] FIG. 4 is a cross-sectional view illustrating a substrate
holder 103 and a rotation driver 105 in accordance with one
embodiment of the present disclosure. The substrate holder 103 is
controllable to hold the substrate 104 and immerse it into the
electroplating solution 102. In one embodiment, the substrate
holder 103 may be a clamshell-type substrate holder comprising a
cone member 103a, cup member 103b and seal (flange) member 103c,
wherein the cup member 103b and seal member 103c are annular in
shape. When the substrate 104 is clamped within the cavity formed
by the cone member 103a and the cup member 103b, the seal member
103c would press against the plating surface 104a of the substrate
104 (namely the active surface of the substrate 104). This forms a
seal between the seal member 103c and a perimeter region of the
plating surface 104a of the substrate 104 while simultaneously
forming the electrical connection between a plurality of contacts
provided within the substrate holder 103 (not shown) and the
plating surface 104a of the substrate 104. The seal with the
plating surface 104a prevents the electroplating solution 102 from
contacting the edge of the substrate 104, the rest of the edge of
the substrate 104 and the plurality of contacts and thus prevents
the associated electrolyte contamination from the electroplating
solution 102. (only a targeted portion of the plating surface 104a
of the substrate 104 is exposed to the electroplating solution 102
during electroplating cycle)
[0034] In one embodiment, the rotation driver 105 may comprise a
rotatable spindle 105a and a slip ring assembly 105b (which
comprises a plurality of slip rings). Slip ring assembly 105b
mounted on and electrically isolated from the rotatable spindle
105a are electrically connected to the substrate holder 103 by
electric interconnects/wires (not shown) inside of the rotatable
spindle 105a. Each of the plurality of slip rings of the slip ring
assembly 105b in combination with a corresponding brush (not shown)
enable electrical connection between external electrical components
(e.g. power supply unit 108 of FIG. 2) and the substrate holder 103
when the rotatable spindle 105a is rotating. One or more slip rings
are typically used to provide one or more channels (electrical
pathways electrically isolated from one another). For example, four
or six slip rings may be used.
[0035] In one embodiment, the rotatable spindle 105a is driven by a
motor (not shown). Mounting the cone member 103a of the substrate
holder 103 on the rotatable spindle 105a advantageously allows the
substrate holder 103 and the substrate 104 to be rotated after (or
before, upon) being immersed in the electroplating solution 102.
This prevents bubble entrapment on the plating surface 104a of the
substrate 104, ensures uniformity of the plating and averaging
possible disturbances and improves electrolyte transport to the
substrate 104. Further, the thickness profile of the electroplated
layer can readily be adjusted by changing the rotational speed of
the rotatable spindle 105a. Different rotational speeds may be
employed for different operations. For immersing the substrate, the
rotational speed is preferably between about 1 and 150 rpm. For a
200 mm diameter substrate (wafer), the speed is preferably between
about 100 and 150 rpm. For a 300 mm diameter substrate (wafer), the
speed is preferably between about 50 and 100 rpm.
[0036] Another approach for preventing bubble entrapment on the
plating surface 104a of the substrate 104 is angled immersion,
which is depicted in FIG. 5 (which is a cross-sectional view
illustrating a substrate holder and a rotation driver in accordance
with one embodiment of the present disclosure). The configuration
of FIG. 5 allows immersion of the substrate 104 at an angle with
respect to the surface 102a of the electroplating solution 102.
Specifically, angled immersion reduces the problems of bubble
entrapment on the plating surface 104a of the substrate 104.
Depending on the different electroplating processes and the details
of the substrate holder 103 (e.g., clamshell-type substrate
holder), different angles may be used. Note that electroplating at
an angle helps also prevent entrapment of bubbles on the plating
surface during electroplating and defects in the plated film are
reduced when angled plating is employed. In one embodiment, the
angle of the plating surface 104a of the substrate 104 with respect
to the surface 102a of the electroplating solution 102 is
preferably about 1 to about 5 degrees. In one embodiment, the angle
is about 4 to about 5 degrees. Furthermore, the substrate 104 is
preferably moved into the electroplating solution 102 at a speed of
between about 5 and 50 millimeters/second. More preferably, the
substrate 104 is moved into the electroplating solution 102 at a
speed of between about 5 and 25 millimeters/second. Even more
preferably, the substrate 104 is moved into the electroplating
solution 102 at a speed of between about 8 and 15
millimeters/second. Most preferably, the substrate 104 is moved
into the electroplating solution 102 at a speed of about 12
millimeters/second.
[0037] FIG. 6 is a schematic diagram illustrating an electroplating
apparatus 600 for electrochemically plating a substrate. The
electroplating apparatus 600 comprises: an electroplating cell 101
(for containing the electroplating solution 102). The
electroplating apparatus 600 comprises a substrate holder 103 for
holding a substrate 104. The electroplating apparatus 600 further
comprises a rotation driver 105 and an anode 107, wherein a voltage
V applied across the rotation driver 105 and the anode 107 causes
an electric current I.sub.3 to flow from the rotation driver 105 to
the anode 107.
[0038] FIG. 7 is a schematic diagram illustrating an electroplating
apparatus 700 for electrochemically plating a substrate in
accordance with one embodiment of the present disclosure. The
electroplating apparatus 700 comprises an electroplating cell 101,
a substrate holder 103, a rotation driver 105, an anode 107 and a
current regulating member 109. Similarly, the electroplating cell
101 is used for containing an electroplating solution 102. The
substrate holder 103 is capable of holding a substrate 104 in the
electroplating solution 102. The rotation driver 105 is configured
for rotating the substrate 104. The current regulating member 109
is electrically coupled between the rotation driver 105 and the
anode 107, wherein a voltage V applied across the current
regulating member 109 and the anode 107 causes an electric current
I.sub.4 to flow from the current regulating member 109 to the anode
107. The electric current I.sub.4 would flow from the current
regulating member 109 through the anode 107, the electroplating
solution 102, the substrate 104, the substrate holder 103, the
rotation driver 105 and back to the current regulating member 109.
The flow of the electric current I.sub.4 through the electric loop
would cause the deposition of a conductive material of the
electroplating solution 102 onto the substrate 104.
[0039] The current regulating member 109 serves to provide a
predetermined impedance value for the electric loop. The
predetermined impedance is such selected that the variation of the
electric current I.sub.4 flowing through the electric loop is kept
within a smaller range compared to the electric current I.sub.3
flowing through the electric loop (which is measured in the absence
of the current regulating member 109). Preferably, the
predetermined impedance value ranges from 0.02 m.OMEGA. to
20.OMEGA.. More preferably, the predetermined impedance value
ranges from 0.05 m.OMEGA. to 5.OMEGA.. Yet more preferably, the
predetermined impedance value ranges from 0.1 m.OMEGA. to 1.OMEGA..
Most preferably, the predetermined impedance value is 50 m.OMEGA..
The total impedance of the electric loop ranges from 1.OMEGA. to
50.OMEGA..
[0040] FIG. 8 is a flowchart of a method for electrochemically
plating a substrate. In operation 801, a substrate is immersed into
an electroplating solution. In operation 802, an anode is provided
and is electrically coupled to the electroplating solution (e.g.,
being immersed into an electroplating solution). Operation 803
discloses forming an electric loop starting from a power supply to
the anode, the electroplating solution, the substrate, and back to
the power supply (wherein an electric current flows from the power
supply to the anode, the electroplating solution, the substrate,
and back to the power supply). In operation 804, a current
regulating member with a predetermined impedance value is provided
on the electric loop, wherein the predetermined impedance is such
selected that the variation of the electric current flowing through
the electric loop is kept within a smaller range compared to that
measured in the absence of the current regulating member, wherein
the flow of the electric current through the electric loop causes
the deposition of a conductive material onto the substrate.
Preferably, the predetermined impedance value ranges from 0.02
m.OMEGA. to 20.OMEGA.. More preferably, the predetermined impedance
value ranges from 0.05 m.OMEGA. to 5.OMEGA.. Yet more preferably,
the predetermined impedance value ranges from 0.1 m.OMEGA. to
1.OMEGA.. Most preferably, the predetermined impedance value is 50
m.OMEGA.. The total impedance of the electric loop ranges from
1.OMEGA. to 50.OMEGA..
[0041] In one embodiment, an operation of forming additional
multiple conductive metal layers is performed prior to operation
801 (namely, immersing the substrate into the electroplating
solution). First, a barrier layer, preferably comprising tantalum,
tantalum nitride (TaN), titanium nitride (TiN), or any suitable
material, may be pre-deposited over a to-be-plated surface of the
substrate. The barrier layer is typically deposited over the
to-be-plated surface using physical vapor deposition (PVD) by
sputtering or a chemical vapor deposition (CVD) process. The
barrier layer limits the diffusion of copper into the semiconductor
substrate (because copper reacts with SiO2, it is necessary to form
a barrier layer first) and any dielectric layer thereof, thereby
increasing reliability. Preferably, the barrier layer has a film
thickness between about 25 angstroms and about 500 angstroms for an
interconnect structure/feature having sub-micron dimension. In one
example, the barrier layer has a thickness between about 50
angstroms and about 3000 angstroms. Second, a copper seed layer may
be deposited over the barrier layer using PVD. The copper seed
layer provides good adhesion for subsequently electroplated copper.
In one example the seed layer has a thickness between about 50
angstroms and about 3000 angstroms. The seed layer may be patterned
for subsequent formation of deposited copper.
[0042] In addition, after electroplating, the plated surface of a
substrate may be planarized, e.g., by chemical mechanical polishing
(CMP), to define a conductive interconnect feature. Chemical
mechanical planarization is a process that can remove topography
from a plated surface of the substrate. Chemical mechanical
planarization is used to planarize the plated surface for following
fabrication processes. Chemical mechanical planarization is the
preferred planarization step utilized in deep sub-micron IC
manufacturing. For chemical mechanical planarization, the polishing
action is partly mechanical and partly chemical. The mechanical
element of the process applies downward pressure while the chemical
reaction that takes place increases the material removal rate and
this is usually tailored to suit the type of material being
processed.
[0043] Some embodiments of the present disclosure provide an
electroplating apparatus for electrochemically plating a substrate,
comprising an electroplating cell for containing an electroplating
solution; a substrate holder for holding a substrate in the
electroplating solution; a rotation driver electrically coupled to
the substrate holder and configured to rotate the substrate holder;
a power distribution assembly electrically coupled to the rotation
driver; an anode disposed within the electroplating cell, the anode
being immersed in the electroplating solution; a power supply unit
electrically coupled between the anode and the power distribution
assembly, thereby forming an electric loop; and a current
regulating member for providing a predetermined impedance value for
the electric loop, wherein a voltage provided by the power supply
unit causes an electric current to flow through the electric loop,
and the predetermined impedance is such selected that the variation
of the electric current flowing through the electric loop is kept
within a smaller range compared to that measured in the absence of
the current regulating member.
[0044] Some embodiments of the present disclosure provide an
electroplating apparatus for electrochemically plating a substrate,
comprising: an electroplating cell for containing an electroplating
solution; a substrate holder for holding a substrate in the
electroplating solution; a rotation driver electrically coupled to
the substrate holder and configured to rotate the substrate holder;
an anode disposed within the electroplating cell, the anode being
immersed in the electroplating solution, wherein a voltage applied
across the rotation driver and the anode causes an electric current
to flow from the rotation driver to the anode; and a current
regulating member electrically coupled to the rotation driver,
wherein a predetermined impedance value of the current regulating
member is such selected that the variation in the electric current
is kept within a smaller range compared to that measured in the
absence of the current regulating member.
[0045] Some embodiments of the present disclosure provide an
electroplating method for electrochemically plating a substrate,
comprising: immersing a substrate into an electroplating solution;
electrically coupling an anode to the electroplating solution;
forming an electric loop in which an electric current flows from a
power supply to the anode, the electroplating solution, the
substrate, and back to the power supply; and providing a current
regulating member with a predetermined impedance value on the
electric loop, wherein the predetermined impedance is such selected
that the variation of the electric current flowing through the
electric loop is kept within a smaller range compared to that
measured in the absence of the current regulating member, wherein
the flow of the electric current through the electric loop causes
the deposition of a conductive material onto the substrate.
[0046] The methods and features of this disclosure have been
sufficiently described in the above examples and descriptions. It
should be understood that any modifications or changes without
departing from the spirit of the disclosure are intended to be
covered in the protection scope of the disclosure.
[0047] Moreover, the scope of the present application is not
intended to be limited to the particular embodiments of the
process, machine, manufacture, and composition of matter, means,
methods and steps described in the specification. As those skilled
in the art will readily appreciate from the disclosure of the
present disclosure, processes, machines, manufacture, composition
of matter, means, methods or steps presently existing or later to
be developed, that perform substantially the same function or
achieve substantially the same result as the corresponding
embodiments described herein may be utilized according to the
present disclosure. Accordingly, the appended claims are intended
to include within their scope such as processes, machines,
manufacture, compositions of matter, means, methods or
steps/operations. In addition, each claim constitutes a separate
embodiment, and the combination of various claims and embodiments
are within the scope of the disclosure.
* * * * *