Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Controlling current distribution within bath
Reexamination Certificate
2000-07-21
2002-07-02
Valentine, Donald R. (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Controlling current distribution within bath
C205S118000, C205S672000, C204S22400M, C204S22400M
Reexamination Certificate
active
06413403
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and structures by which improved distribution of chemical solutions, such as plating solutions, etching solutions, or electroetching solutions, is provided to a pad/substrate interface in a plating or etching apparatus that uses an anode/pad assembly. According to the invention, a system of channels is designed under the pad to distribute the solution more evenly and to prevent the solution from coming directly from the pad support member and hitting the substrate surface.
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 work piece, such as a semiconductor substrate, or perform various combinations of such depositing, removing and planarizing operations. Deposition of conductive materials such as copper, gold, nickel, rhodium, platinum, magnetic materials, and their various alloys may be performed, for example, by electrodeposition.
In inlaid metal technology, a workpiece, such as a substrate
10
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. The undesirable excess conductive material over the field region is called “overburden”. This variation in thickness or “overburden” 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. Several improved 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. The pad design may also be used in a polishing technique such as CMP.
It is an object of the present invention to provide an improved method and an improved 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. The improved method eliminates direct communication of electrolyte fluid flow from a pad support member to the substrate surface and permits electrolyte fluid to be supplied at greater pressures and flow rates.
This and other objects of the present invention are obtained by a particular apparatus which is capable of assisting in controlling an electrolyte flow and distribution of an electric field, a magnetic field, or an electromagnetic field in order to process a substrate. The apparatus includes a support member having a top surface and a bottom surface, the support member containing at least one support member electrolyte channel. Each support member electrolyte channel forms a passage between the top surface and the bottom surface of the support member and allows the electrolyte to flow therethrough. The apparatus also includes a pad, attachable to the support member, which contains at least one set of pad electrolyte channels also allowing for electrolyte flow therethrough to the substrate. Each support member electrolyte channel is connected to one set of pad electrolyte channels by a particular fluid distribution structure.
According to one embodiment of the invention, each support member electrolyte channel is one of a plurality of support member electrolyte channels, and each set of pad electrolyte channels is one of a plurality of sets of pad electrolyte channels.
The fluid distribution structure includes distribution channels interconnecting each support member electrolyte channel to a set of pad electrolyte channels. In one embodiment, the distribution channels are formed in the pad, while in another embodiment, the distribution chann
Basol Bulent
Lindquist Paul
Talieh Homayoun
Uzoh Cyprian
Crowell & Moring LLP
NuTool Inc.
Smith-Hicks Erica
Valentine Donald R.
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