U.S. patent application number 11/232026 was filed with the patent office on 2006-01-19 for multi step electrodeposition process for reducing defects and minimizing film thickness.
Invention is credited to Bulent M. Basol, Homayoun Talieh, Cyprian E. Uzoh.
Application Number | 20060011485 11/232026 |
Document ID | / |
Family ID | 26896939 |
Filed Date | 2006-01-19 |
United States Patent
Application |
20060011485 |
Kind Code |
A1 |
Basol; Bulent M. ; et
al. |
January 19, 2006 |
Multi step electrodeposition process for reducing defects and
minimizing film thickness
Abstract
The present invention relates to a method for forming a planar
conductive surface on a wafer. In one aspect, the present invention
uses a no-contact process with electrochemical deposition, followed
by a contact process with electrochemical mechanical
deposition.
Inventors: |
Basol; Bulent M.; (Manhattan
Beach, CA) ; Uzoh; Cyprian E.; (San Jose, CA)
; Talieh; Homayoun; (San Jose, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET
FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Family ID: |
26896939 |
Appl. No.: |
11/232026 |
Filed: |
September 20, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10201604 |
Jul 22, 2002 |
6946066 |
|
|
11232026 |
Sep 20, 2005 |
|
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60306758 |
Jul 20, 2001 |
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Current U.S.
Class: |
205/123 ;
205/170; 257/E21.175; 257/E21.583; 257/E21.585 |
Current CPC
Class: |
H01L 21/2885 20130101;
C25D 7/123 20130101; H01L 21/7684 20130101; C25D 5/22 20130101;
H01L 21/76877 20130101; C25D 5/02 20130101 |
Class at
Publication: |
205/123 ;
205/170 |
International
Class: |
C25D 5/10 20060101
C25D005/10; C25D 5/02 20060101 C25D005/02 |
Claims
1. An electrochemical processing method for operating upon a wafer,
the wafer having a top surface with first and second cavities
disposed thereon, the first cavity having a narrower width than a
second cavity, and a conductive layer having a conductive top
surface associated therewith disposed on the top surface of the
wafer and on the first and second cavities, the method comprising:
performing electrochemical deposition on the conductive layer of
the wafer to result in at least the first cavity being at least
partially filled with conductive material; and performing
electrochemical mechanical deposition on the conductive layer of
the wafer in which the first cavity is at least partially filled
with more conductive material to result in at least some of any
remaining cavity within the first and second cavities being further
filled with more conductive material, wherein physical contact and
relative motion is maintained between the conductive top surface of
the conductive layer disposed over the top surface of the wafer and
a workpiece surface influencing device for at least a period of the
electrochemical mechanical deposition.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 10/201,604, filed Jul. 22, 2002, which claims
priority to U.S. Provisional Application No. 60/306,758, filed Jul.
20, 2001. Both of the foregoing applications are hereby
incorporated by reference herein in their entireties.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally relates to semiconductor
processing technologies and, more particularly, to an
electrodepositing process that deposits thin and planar layers.
[0004] 2. Description of the Related Art
[0005] Conventional semiconductor devices generally include a
semiconductor substrate, usually a silicon substrate, and a
plurality of sequentially formed dielectric interlayers such as
silicon dioxide and conductive paths or interconnects made of
conductive materials. The interconnects are usually formed by
filling a conductive material in trenches etched into the
dielectric interlayers. In an integrated circuit, multiple levels
of interconnect networks laterally extend with respect to the
substrate surface. The interconnects formed in different layers can
also be electrically connected using vias or contacts. A conductive
material filling process of such features, i.e., via openings,
trenches, dual damascene structures, pads or contacts can be
carried out by depositing a conductive material over the substrate
including such features.
[0006] Copper and copper alloys have recently received considerable
attention as interconnect materials because of their superior
electromigration and low resistivity characteristics.
Electrodeposition is typically used to deposit copper into the
features on the wafer surface. In the prior art, however, after
performing the material deposition to fill such features or
cavities, a variation in the thickness of the deposited copper
material inevitably occurs on the surface of the substrate. The
excess copper on the wafer surface is called overburden. The
conventional deposition methods produce a thick overburden with a
surface with large variations across the wafer.
[0007] An etching, an electropolishing/electroetching or a chemical
mechanical polishing (CMP), or other material removal steps may be
employed to remove the overburden and planarize the surface. Such
processes remove the conductive material overburden off the surface
of the wafer, particularly the field regions, thereby leaving the
conductive materials primarily disposed within the features, such
as vias, trenches and the like. However, the planarization and the
removal of the large overburden resulting from the conventional
deposition methods is expensive and time consuming. Furthermore,
large variations on the non-planar surface of the overburden result
in defects such as dishing and erosion, after the overburden
removal and planarization steps.
[0008] To this end, there is a need for a process for forming
conductive layers with planar surface and minimum thickness of the
overburden layer.
SUMMARY OF THE INVENTION
[0009] The present invention relates to an apparatus and method for
forming a planar and thin layer on a front surface of a workpiece.
The apparatus according to the present invention includes an
electrode and a workpiece surface influencing device, also referred
to as a mask plate, disposed in between the electrode and the front
surface of the workpiece. The workpiece surface influencing device
preferably includes at least one channel for allowing a plating
solution to flow from the electrode to the front surface of the
workpiece. The channel also includes an open end for allowing the
plating solution to flow out of the workpiece surface influencing
device.
[0010] The method according to the present invention includes
positioning the front surface of the workpiece in close proximity
to the workpiece surface influencing device. Thereafter, the
plating solution containing the conductive material is flowed to
the front surface of the workpiece through the channel in the
workpiece surface influencing device. An electric potential is
applied between the workpiece and the electrode both of which are
in physical contact with the plating solution, thereby allowing a
conductive material to be formed on the front surface of the
workpiece using an electrochemical deposition process. In a
subsequent electrochemical mechanical deposition process, the front
surface of the workpiece is then swept or polished using a top
surface of the workpiece surface influencing device as an electric
potential is applied. In the next step, an electric potential
having a polarity opposite the electric potential used in the
electrochemical deposition process and the electrochemical
mechanical deposition process is applied to the workpiece and the
electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other features and advantages of the invention
are further described in the detailed description which follows,
with reference to the drawings by way of non-limiting exemplary
embodiments of the invention, wherein like reference numerals
represent similar parts of the invention throughout several views
and wherein:
[0012] FIG. 1 schematically shows a portion of exemplary electro
plating/etching system that may be used for the present
invention;
[0013] FIG. 2 illustrates a top view of a mask plate;
[0014] FIG. 3 illustrates a perspective view of a portion of the
mask plate;
[0015] FIG. 4 shows a first structure, which is formed on the front
surface of the workpiece shown in FIGS. 1 and 3;
[0016] FIG. 5 illustrates a first layer deposited into the cavities
and on the top surfaces of the workpiece;
[0017] FIGS. 6A, 6B and 7 illustrate various profiles that can be
achieved;
[0018] FIGS. 8A and 8B illustrate formation of defects;
[0019] FIG. 9 illustrates further planarizing the growing
deposition layer;
[0020] FIG. 10 illustrates a profile when a no-contact
electroetching process is used;
[0021] FIG. 11 illustrates a profile when a contact electroetching
process is further used; and
[0022] FIG. 12 illustrates a dual damascene structure getting
filled with a conductor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0023] Reference will now be made to the drawings wherein like
numerals refer to like parts throughout. An example of a planar
electro deposition-polishing apparatus that can be used to practice
the present invention is schematically shown in FIGS. 1-3. It
should be noted that, in this application, process of
electroetching, electropolishing, electrochemical etching are all
used to refer to the process where a voltage is applied to a
coating on a substrate in an electrolyte to remove part or all of
the coating.
[0024] Descriptions of various methods and apparatus for
electrodeposition of planar films can be found in the following
patent and pending applications, all commonly owned by the assignee
of the present invention: U.S. Pat. No. 6,176,992 entitled "Method
and Apparatus for Electrochemical Mechanical Deposition," U.S.
application Ser. No. 09/740,701 entitled "Plating Method and
Apparatus that Creates a Differential Between Additive Disposed on
a Top Surface and a Cavity Surface of a Workpiece Using an External
Influence," U.S. application Ser. No. 09/735,546 entitled "Method
and Apparatus For Making Electrical Contact To Wafer Surface for
Full-Face Electroplating or Electropolishing" and U.S. application
Ser. No. 09/760,757 entitled "Method and Apparatus for
Electrodeposition of Uniform Film with Minimal Edge Exclusion on
Substrate." When used as an electropolishing system in a removal
process, the anode and cathode become reversed, as described in
U.S. Pat. No. 6,176,992 referred to above. When used for
electrodeposition in a deposition process, the system of the
present invention can deposit a conductive material such as copper
on a workpiece such as a semiconductor wafer. Although copper is
used as an example material that is deposited and/or removed
herein, the present invention may be used when depositing or
removing other conductors, for example Ni, Pd, Pt, Au, Pb, Sn, Ag
and their alloys.
[0025] FIG. 1 schematically shows a portion of exemplary electro
plating/etching system 100 that may be used for the present
invention. The plating system 100 has an electrode 102, a workpiece
104 and a mask plate 106. A copper plating solution containing
copper ions makes contact with the electrode 102 and the workpiece
104. In FIG. 1, although the electrode 102 is shown under the mask
plate 106, it can be positioned anywhere in the system 100 as long
as the electrode 102 makes contact with the plating solution. The
workpiece 104 may be a substrate or wafer, preferably a silicon
wafer portion. The workpiece 104 comprises a front surface 108 to
be plated with copper and a back surface 110 to be held by a
carrier head (not shown). The front surface 108 may comprise the
features shown in FIG. 4. An exemplary copper plating solution may
be a copper base solution such as a solution containing CuSO.sub.4,
H.sub.2SO.sub.4, Cl.sup.-.and additives. The additives are
generally chemicals called suppressors, accelerators, levelers and
brighteners etc., which affect the grain size, morphology, and
filling of the small features as well as smoothness of the
deposited copper. Such additives are well known in the copper
plating industry. The copper plating solution used in this
invention may also comprise alternative additive chemistries. One
such alternative additive chemistry is disclosed in the pending
U.S. application Ser. No. 09/544,558 entitled "Modified Plating
Solution for Plating and Planarization and Process Utilizing Same"
which is commonly owned by the assignee of the present invention.
Other alternative chemistries, agents can also be used with the
plating solution of the present invention to affect the properties
of the deposited material and are within the scope of this
invention.
[0026] FIG. 2 illustrates a top view and FIG. 3 illustrates a
perspective view of a portion of the workpiece surface influencing
device or mask plate 106. The illustrated portion of the mask plate
106 comprises a top surface 112 and a bottom surface 114. The mask
plate portion 106 also comprises a channel 116 extending between
the top and the bottom surfaces 112, 114 and defined by a `V`
shaped sidewall 118 having a first wall 118a and a second wall
118b. The channel 116 laterally extends between a closed end 120
and an open end 122. The top surface 112 of the mask plate 106 may
be abrasive or an abrasive pad material may be attached to it.
[0027] It should be noted that various channel/opening designs can
be used for the mask plate 106. The "V" shape of the channel in
FIG. 2 is just an example. Whatever the shape of the channels, it
is, however, important to note that the mask plate 106 has openings
such as channel 116 to allow the plating solution to flow through
towards the workpiece 104. For the purpose of clarification,
although only one channel is shown in FIG. 2, it is understood that
there are typically multiple channels. Channels also exist in
porous pads, as described in U.S. Pat. No. 6,176,992 referred to
above. Accordingly, the term workpiece surface influencing device
is used to collectively refer to such structures that are used to
create an influence on the workpiece surface.
[0028] FIG. 3 exemplifies how the planar plating process through
the channel 116 progresses as the workpiece 104 is rotated about
the axis 126 on the mask plate 106 as described above. During an
electroplating process, the front surface 108 of the workpiece 104
is brought into close proximity, or contact with, the top surface
112 of the mask plate 106 for metal deposition. As a plating
solution, depicted by arrows 124, is delivered through the channel
116, the workpiece 104 is rotated about the axis 126 while the
front surface 108 contacts the top surface 112 of the mask plate
106. As shown in FIG. 3, the axis 126 may run directly through the
closed end 120 of the channel 116. As the solution is flowed
through the channel 116, it makes contact with the front surface
108 of the workpiece 104. Under an applied potential between the
workpiece 104 and the electrode 102 in the presence of the solution
124 that is flowed through the channel 116, copper is plated on the
front surface 108 of the workpiece 104.
[0029] In one embodiment, the front surface 108 is also swept by
the top surface 112 of the mask plate 106 during certain period of
the plating process. The sweeping caused by the top surface 112 of
the mask plate 106 assists in obtaining planar deposition of the
metal. The solution 124, which is continuously delivered under
pressure, will then flow through the channel 116 towards the open
end 122 and exit the mask plate 106. During this process,
mechanical polishing or sweeping with the mask plate 106 provides
substantially flat deposition layers. During the mechanical
sweeping, the workpiece 104 makes contact with the mask plate 106
with a pressure in the range of 0.1 psi to 5 psi, preferably 0.2
psi to 1 psi.
[0030] It is noted that the above description described rotation
and movement of the workpiece 104, assumes that the mask plate 106
is stationary. It is understood that the system 100, as described
above, will allow for either the workpiece 104 or the mask plate
106 to move, or for both of them to move, thereby creating the same
relative affect. For ease of description, however, the invention
will be described in terms of movement of the workpiece 104.
Furthermore, the shape and form of the channel(s) 116 may be
different. In addition to rotating, the workpiece 104 may also be
moved laterally for better uniformity in coating. During the
process, the workpiece 104 may be rotated in the range of 5 to 300
revolutions per minute (rpm), preferably 20 to 200 rpm while
applying a lateral x-motion typically more than 1 centimeter (cm),
preferably between 1 to 30 cm. Further, the velocity in the
x-motion may be more than 0.1 millimeters per second (mm/s), and
preferably between 1 to 30 mm/s. It should also be noted that FIGS.
1 to 3 only show portions of the system components. Therefore, the
sizes and shapes of the each piece such as mask plate 106,
electrode 102 are not meant to be limited to the sizes and shapes
shown in the FIGS. 1 to 3.
[0031] The preferred process implementing this technology to
electroplate a workpiece surface is described below. FIG. 4 shows a
first structure 200, which is formed on the front surface 108 of
the workpiece 104 shown in FIGS. 1 and 3. The first structure 200
is comprised of a patterned layer 202, preferably an insulating
layer such as silicon oxide, formed on a base layer 108. The first
structure 200 may be formed using well known patterning and etching
techniques pursuant to metal interconnect design rules. In this
embodiment, the insulating layer 202 includes cavities or gaps,
namely a first cavity 204, a second cavity 206 and a third cavity
208, separated from one another by interlayer regions 210. Each
cavity 204, 206, 208 is defined by a bottom wall 212 and side walls
214. The thickness of the inter layer regions 210 is determined as
the distance between the bottom wall 212, or the base layer 108 top
surface and the top surface 216 of the interlayer regions 210. In
this example, the thickness of the interlayer regions 210 is equal
to the depth of the cavities 204, 206 and 208. The top surfaces 216
of the interlayer regions 210 are also called field regions.
[0032] In this embodiment, the cavities 204, 206, 208 can be formed
such that the first cavity 204 may be a via or a narrow trench, the
second cavity 206 may be a mid-size trench or a large via, and the
third cavity 208 may be a trench or a large pad. In this respect,
the first cavity 204 may have a width of less than 1 micrometers.
The second cavity 206 may have a width of 1-5 micrometers, and the
third cavity 208 may have a width of more than 5 micrometers. The
depth of the cavities may be larger than 0.3 to 10 micrometers, but
preferably 0.3-5 micrometers. At this point of the process,
although not shown in the drawings, typically one or more thin
layers of barrier or glue layer materials, for example, Ta, TaN,
Ti, TiN, or WN can be deposited, using well known processes in the
art, as a barrier or glue layer. Multiple layers of different
barrier materials, such as bilayers formed with sequential
deposition of Ta and TaN or Ti and TiN can also be constructed.
Subsequently, a thin film of copper is deposited as the seed layer
on top of the barrier layer for the subsequent electroplated copper
layer. The copper seed layer provides a base layer on which
nucleation and growth of the subsequent deposition layer can
occur.
[0033] Referring to FIG. 5, a first layer 218 is deposited into the
cavities 204, 206, 208 and on the top surfaces 216. The deposition
process is performed using the exemplary system 100 described
above. It is known in the art that copper electroplating solutions
are formulated with additives that promote bottom up plating in
narrow features/cavities. When workpiece with various size features
are coated with copper using these electrolytes, the small
features, i.e., typically features that are smaller than 1
micrometer, are filled up easily and quickly with copper plating
from the bottom of the cavity towards its top. Large features are
coated in a conformal manner because additives can diffuse in and
out of such features without impediment. Medium size features
behave somewhat in between the two extremes.
[0034] In operation, as can be seen in FIG. 1, initially, the front
surface 108 is plated without making contact with the mask plate
106, (i.e., the workpiece 104 is held in close proximity of the
mask plate 106 and moved during the plating). During this stage of
the process, the gap between the wafer front surface and the
surface of the mask plate is preferably about 1-4 millimeters (mm).
This process step will be referred to as "no-contact" plating
hereinafter. Referring back to FIG. 5, at this stage of the
process, the depositing material, which forms the first layer 218,
fills the first cavity 204 completely through bottom-up filling
process and covers the walls and the bottom of the third cavity 208
in a conformal fashion. Further, during the process, the material
deposited into the second cavity 206 partially fills it in a
somewhat bottom-up fashion. At this stage of the process, although
a portion of the first layer 218 partially fills the second cavity
206 and makes it smaller, the remaining opening still maintains its
high aspect ratio (depth D/width W), (i.e., D>W). It is
understood that the second cavity 206 may be any cavity that is
partially filled and that can be used to determine if the D>W
condition exist. The no-contact plating may be continued as long as
D>W condition exists in any of the cavities. Preferably, contact
plating may not be initiated as long as the D>W condition
exists. As will be described below, if the contact plating is
initiated with D>W condition existing, defects may form.
[0035] Accordingly, as shown in FIGS. 6A and 7, depending on the
process parameters used, no contact plating may result in a second
layer 220 having two types of surface profile, namely flat profile
(FIG. 6A) and overfill profile (FIG. 7) respectively. In the
preferred flat profile, as shown in FIG. 6A, as the no-contact
plating process is continued and the second layer 220 is coated on
the first layer 218, the aspect ratio of the second cavity 206 is
smaller such that the width W of the cavity becomes larger than the
depth D. That is, W>D condition exists. This condition may also
be expressed in terms of the thickness of the selected regions of
the deposited layer and the corresponding growth rate for that
selected thickness value. As shown in FIG. 6B, if rb is the growth
rate from the bottom wall of the second cavity 206 and rw is the
growth rate from the top of the side walls of the second cavity
206, the above given condition W>D can also be expressed
approximately as W.sub.0-2r.sub.w t>(D.sub.0-r.sub.b t), where
W.sub.0 and D.sub.0 are the initial width and the depth of the
cavity before the deposition, and t is the deposition time. It
should be noted that the barrier and seed layers are not shown in
any of the figures for the purpose of clarification.
[0036] Referring to the case of overfill profile (FIG. 7), as the
no-contact plating fills the first cavity 204 an overfill feature
221 such as a bump may form above the first cavity 204. During the
copper plating process, such bumps are possible and formed due to
the overfilling of the cavities. Although mechanism is not fully
understood, it is believed that such bumps form due to preferential
or accelerated adsorption of growth accelerating additive species
in the small cavities. In such morphologies, due to the existence
of the bump 221, in the subsequent contact plating stage, as
opposed to the case of the flat profile, a thick deposition layer
is required to fill the cavities 206,208 and to cover the bump 221.
This is time consuming and reduces system efficiency. Therefore,
the flat profile is the preferred surface profile in this
embodiment. However, if the bumps are formed, the second step of
the process eliminates them by planarizing the surface.
[0037] Referring back to FIG. 6A, flatness of the second layer 220
may be obtained using various techniques such as using flatness
enhancing agents in the electrolyte solution or using a pulse power
supply to energize the anode and the cathode. Flatness enhancing
agents may be exemplified as levelers. Levelers are well known
chemicals in the electroplating technology and used to effectively
suppress the growth of bumps on the depositing layers. A pulse
power supply or a variable voltage power supply can also minimize
or eliminate the over fill bump. A technique called reverse pulse
plating process may be used to obtain flat surface profiles over
small features. In this approach, the voltage pulses make the
workpiece surface periodically cathodic to deposit copper on it and
anodic for a shorter time to etchback a portion of the deposited
material so that flatness of the layer can be achieved. The pulse
power supply can also be used during the second step or the contact
plating and third step or the electroetching step of the process of
the present invention. Referring back to FIGS. 6A and 6B, once the
W.sub.0-2 r.sub.wt>(D.sub.0-r.sub.b t) condition is satisfied
for all the remaining features (i.e., the mid-size and the large
features), the process is continued with the "contact" plating
stage of the process, or a second stage of the process, to
completely fill the cavities. At the "contact" plating stage of the
process, the front surface 108 is contacted to the top surface 112
of the mask plate 106, while the deposition process continues. If
the contact plating is initiated without satisfying the W>D
condition, defects may form.
[0038] FIGS. 8A and 8B exemplifies formation of such defects. As
shown in FIG. 8A, when the contact plating is initiated the mask
plate 106 sweeps or mechanically influences the top portion 218A of
the layer 218 but not an inner portion 218B and a mouth portion
218C covering the second cavity 206 side walls and the bottom wall.
This in turn reduces the growth rate at the top portion 218A in
comparison to both the inner portion 218B and the mouth portion
218C. Further the mechanical influence increases lateral growth
rate of the copper at the mouth portion 218C in comparison to the
inner portion 218B since it creates an additive differential
between the inner portion 218B. This situation can be seen in FIG.
8B where as consecutive layers 219A, 219B, 219C are coated with
contact plating, the layers 219A-219C grow faster at locations
covering the mouth portion 218C than the inner portion 218B.
Portions of the layers 219A-219C covering the top portion 218A grow
slowly due to the mechanical influence created by the contacting
mask plate. Such non-conformal growth pattern eventually forms a
defect 223, often a hole, entrapping electrolyte solution which is
an unwanted situation in electroplating.
[0039] As shown in FIG. 9, the mechanical influence created by the
contacting mask plate 106 further planarizes the growing deposition
layer, and if the overfill profile is used, the mechanical
influence removes the bump 221 as well (see FIG. 7). This results
in a third deposition layer 224, which is a substantially
planarized layer, on the workpiece 104. The contact step of the
process may proceed in such manner that the workpiece 104 may make
contact with the mask plate 106 intermediately (i.e., in a
discontinuous fashion). This still results in planarized layer and
smoothes the top layer. Further, such contact and no-contact action
may be repeated multiple times.
[0040] In the following stage of the process, by reversing the
polarization of the electrodes (i.e., by applying negative
potential to anode electrode and by applying positive potential to
the workpiece), the layer 224 can be electroetched down to a
predetermined thickness over the interlayer regions. In this third
step, electroetching process may be performed using the same
electrolyte solution used during the electrodeposition stage and
using the same system above. As in the case of electrodeposition,
the electroetching may be also carried out by "no-contact"
electroetching and "contact" electroetching process steps.
Accordingly, as illustrated in FIG. 10, with the no-contact
electroetching process, thickness `d` of the layer 224 can be
reduced down to thickness A in a planar manner. As illustrated in
FIG. 11, with the application of the contact electroetching
process, contacting mask plate 106 reduces the thickness of the
layer 224 in a planar fashion, down to thickness B.
[0041] Contact and no-contact electroetching can be used
sequentially and multiple times using the same or different process
parameters such as by employing different current levels, different
wafer pressure levels and different rotational and lateral
velocities. If contact and no-contact electroetching processes are
performed in a multiple fashion, the process may be terminated with
contact electroetching process. As mentioned above, the contact
step smoothes the layer. The thickness B may be less than the depth
D.sub.o of the cavities 204, 206 and 208, and preferably less than
half of the depth (D.sub.0/2) of the cavities. The third step of
the process may be performed in the same electrolyte or solution
that is used for the deposition process. Further, this step may be
performed in the same process module that the deposition is carried
out and subsequent to the deposition process.
[0042] The method of the above embodiment can fill cavities of any
shape and form. One example, a dual damascene structure 300, is
shown in FIG. 12. The dual damascene structure 300 has a via 302
and a trench 304 formed in an insulator 306. The via 302 may be a
narrow via, and the trench 304 may be a mid size or a larger
trench. If the above process is used, in first step of the process
or no contact step, the depositing material fills the via 302 and
conformally coats the trench 304 with a first layer 308. In a
second step, or contact step, of the process, the depositing
material fills the trench completely with a second layer 310 and
the mechanical influence created by the contacting mask plate 106
planarizes the growing second layer 310. In the third step, a layer
312 that is formed by sequentially depositing layers 308 and 310 is
electroetched down to a predetermined thickness "C" as shown in
FIG. 12.
[0043] Although various preferred embodiments have been described
in detail above, those skilled in the art will readily appreciate
that many modifications of the exemplary embodiment are possible
without materially departing from the novel teachings and
advantages of this invention.
* * * * *