Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-02-23
2002-07-02
Valentine, Donald R. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S22400M
Reexamination Certificate
active
06413388
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
1. Field of the Invention
The present invention relates to a highly versatile apparatus for depositing, removing, modifying, or polishing a material on a workpiece, such as a substrate. More particularly, the present invention is directed to various pad designs and structures for depositing, removing, modifying and/or polishing a material on a suitable substrate.
2. Description of Related Art
There are numerous processing steps in the fabrication of high performance integrated circuits (ICs), packages, magnetic film heads, thin film display units, and the like. One important step is to deposit, remove, or planarize a conductive or insulative material on a workpiece, such as a semiconductor substrate. Deposition of conductive materials such as copper, gold, nickel, rhodium, and their various alloys may be performed, for example, by electrodeposition.
In inlaid metal technology, a workpiece, such as a substrate shown in
FIG. 1
a
, may consist of various topographical features such as channels
14
and vias
12
etched in a suitable dielectric material
16
. The surface of the etched dielectric material
16
is generally coated with a suitable adhesion/barrier film layer
18
. Over the barrier layer
18
, a suitable plating base layer
20
, often called a “seed layer”, is deposited. A conductive layer
22
is then applied over the plating base layer to fill, and preferably over-fill, the vias
12
and channels
14
etched in the dielectric material
16
as shown in
FIG. 1
c.
The conductive material may be, for example, Cu deposited by way of a chamber-type device
100
(generally shown in
FIG. 1
b
). The chamber device
100
includes a deposition chamber
102
, which contains an anode
104
and electrolyte
106
. The anode
104
may be attached to the bottom of the chamber
102
.
A holder
108
holds the workpiece, such as the substrate
10
. For a detailed description of the holder, reference can be made to the assignee's co-pending application Ser. No. 09/472,523, entitled “Work Piece Carrier Head For Plating and Polishing” filed Dec. 27, 1999, the specification of which is incorporated by reference herein as non-essential matter.
For the deposition process, the substrate
10
is typically immersed in the electrolyte
106
with the aid of the holder
108
, which also provides a way of electrically contacting the substrate
10
. By applying a potential difference between the anode
104
and the substrate
10
(i.e., the cathode), materials may be deposited on or removed from the substrate. For example, when the anode is more positive than the substrate, copper may be deposited on the substrate
10
. If the anode is more negative than the substrate, however, copper may be etched or removed from the substrate. To aid electrolyte agitation and enhance mass transfer, the substrate holder
108
may include a rotatable shaft
112
such that the substrate holder
108
and the substrate
10
can be rotated. The substrate
10
is typically spaced apart from the anode
104
at a distance of at least about 10 mm; this distance may, however, be as great as about 300 mm. The surface of the substrate
10
may contain topographic features, such as the vias
12
and channels
14
illustrated in
FIG. 1
a
. After performing material deposition to fill the various features/cavities using electrolyte containing leveling additives, a variation in the thickness of the deposited conductive material
22
inevitably occurs over the surface of the substrate. This variation in thickness is termed “overburden” and is shown in
FIG. 1
c
with reference to portions
22
a
and
22
b.
After depositing the conductive material
22
on the top surface of the substrate
10
, the substrate
10
is typically transferred to a chemical mechanical polishing (CMP) apparatus in order to polish, planarize, or both polish and planarize the same surface.
FIG. 2
a
illustrates one possible version of a conventional CMP apparatus
200
used to polish/planarize the substrate
10
and/or electrically isolate the deposited conductive material within the particular features located thereon. The substrate, holder
208
, which may be similar to the holder
108
described above, holds and positions the substrate
10
in close proximity to a belt-shaped CMP pad
214
. The belt-shaped pad
214
is adapted to rotate in an endless loop fashion about rollers
216
. The polishing/planarizing process occurs when the rollers
216
rotate; and the pad
214
is moved with a circular motion while making contact with the surface of the substrate
10
. A conventional slurry may also be applied to the pad
214
while the substrate
10
is being polished. The substrate surface after polishing is shown in
FIG. 2
b.
The conventional method for depositing a conductive material produces large variations in material overburden across the substrate as shown in
FIG. 1
c
. The conventional CMP of this large overburden causes defects on the substrate
10
such as dishing
22
c
and dielectric erosion
16
c
also shown in
FIG. 2
b
. It also is responsible for low substrate processing throughput, which is a major source of manufacturing yield loss.
SUMMARY OF THE INVENTION
There is therefore a need for an apparatus that can reduce the time needed during the planarization phase of the fabrication process, and that can simplify the planarization phase itself. In other words, a more efficient and effective method and apparatus for depositing a conductive material on a substrate is needed. Various pad designs and structures are disclosed herein that can be used for depositing conductive material with a very uniform material overburden on a surface of a substrate.
It is an object of the present invention to provide a method and apparatus for performing any of depositing, removing, polishing, and/or modifying operations on conductive material, which is to be applied to or has been applied on a substrate.
It is another object of the present invention to provide a method and apparatus for depositing a conductive material with minimum material overburden.
It is still another object of the invention to provide a method and apparatus for depositing a conductive material with a uniform material overburden across the surface of a substrate.
It is a further object of the invention to provide a method and apparatus for depositing material on a substrate in an efficient and cost-effective manner.
It is still a further object of this invention to provide various pad designs and structures for depositing a conductive material on a substrate.
It is yet another object of this invention to provide a method for mounting a pad having channels, holes or grooves for depositing a conductive material on a substrate.
It is a further object of this invention to provide a method and apparatus to mount a pad to be used for depositing a material on a surface.
It is yet another object of the invention to provide a method and pad to control the uniformity of a deposited material on a substrate.
These and other objects of the present invention are obtained by providing a method and apparatus for simultaneously plating and polishing a conductive material on a substrate. The substrate (or cathode in the deposition process) is disposed in close proximity to a rotating member having a pad material attached thereto. The pad is interposed between the substrate (cathode) and the anode. Upon applying an electrical current or potential between the substrate and the anode in the presence of a suitable electrolyte, the conductive material may be removed or deposited on the cathode.
In a preferred embodiment, the conductive material may be selectively deposited in the cavities of topographical features on the substrate surface, while the pad material minimizes or prevents material depositions in regions above the cavities.
The nature, design, fabrication and mounting of the pad material used in this invention advantageously allow for the modification of material removal from, or the deposition of a high quality conductive material on, a substrate s
Basol Bulent
Talieh Homayoun
Uzoh Cyprian
Crowell & Moring LLP
NuTool Inc.
Smith-Hicks Erica
Valentine Donald R.
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