Abrading – Machine – Endless band tool
Reexamination Certificate
2001-03-30
2004-05-04
Rose, Robert A. (Department: 3723)
Abrading
Machine
Endless band tool
C451S307000
Reexamination Certificate
active
06729945
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to chemical mechanical planarization (CMP) techniques and, more particularly, to the efficient, cost effective, and improved CMP operations.
2. Description of the Related Art
In the fabrication of semiconductor devices, there is a need to perform chemical mechanical planarization (CMP) operations. Typically, integrated circuit devices are in the form of multi-level structures. At the substrate level, transistor devices having diffusion regions are formed. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define the desired functional device. As is well known, patterned conductive layers are insulated from other conductive layers by dielectric materials, such as silicon dioxide. As more metallization levels and associated dielectric layers are formed, the need to planarize the dielectric material grows. Without planarization, fabrication of further metallization layers becomes substantially more difficult due to the variations in the surface topography. In other applications, metallization line patterns are formed in the dielectric material, and then, metal CMP operations are performed to remove excess material.
A chemical mechanical planarization (CMP) system is typically utilized to polish a wafer as described above. A CMP system typically includes system components for handling and polishing the surface of a wafer. Such components can be, for example, an orbital polishing pad, or a linear belt polishing pad. The pad itself is typically made of a polyurethane material or polyurethane in conjunction with other materials such as, for example a stainless steel belt. In operation, the belt pad is put in motion and then a slurry material is applied and spread over the surface of the belt pad. Once the belt pad having slurry on it is moving at a desired rate, the wafer is lowered onto the surface of the belt pad. In this manner, wafer surface that is desired to be planarized is substantially smoothed, much like sandpaper may be used to sand wood. The wafer may then be cleaned in a wafer cleaning system.
FIG. 1A
shows a linear polishing apparatus
10
which is typically utilized in a CMP system. The linear polishing apparatus
10
polishes away materials on a surface of a semiconductor wafer
16
. The material being removed may be a substrate material of the wafer
16
or one or more layers formed on the wafer
16
. Such a layer typically includes one or more of any type of material formed or present during a CMP process such as, for example, dielectric materials, silicon nitride, metals (e.g., aluminum and copper), metal alloys, semiconductor materials, etc. Typically, CMP may be utilized to polish the one or more of the layers on the wafer
16
to planarize a surface layer of the wafer
16
.
The linear polishing apparatus
10
utilizes a polishing belt
12
, which moves linearly in respect to the surface of the wafer
16
. The belt
12
is a continuous belt rotating about rollers (or spindles)
20
. The rollers are typically driven by a motor so that the rotational motion of the rollers
20
causes the polishing belt
12
to be driven in a linear motion
22
with respect to the wafer
16
.
The wafer
16
is held by a wafer carrier
18
. The wafer
16
is typically held in position by mechanical retaining ring and/or by vacuum. The wafer carrier positions the wafer atop the polishing belt
12
so that the surface of the wafer
16
comes in contact with a polishing surface of the polishing belt
12
.
FIG. 1B
shows a side view of the linear polishing apparatus
10
. As discussed above in reference to
FIG. 1A
, the wafer carrier
18
holds the wafer
16
in position over the polishing belt
12
while applying pressure to the polishing belt. The polishing belt
12
is a continuous belt typically made up of a polymer material such as, for example, the IC 1000 made by Rodel, Inc. layered upon a supporting layer. The polishing belt
12
is rotated by the rollers
20
which drives the polishing belt in the linear motion
22
with respect to the wafer
16
. In one example, a fluid bearing platen
24
supports a section of the polishing belt under the region where the wafer
16
is applied. The platen
24
can then be used to apply fluid against the under surface of the supporting layer. The applied fluid thus forms a fluid bearing that creates a polishing pressure on the underside of the polishing belt
12
which is applied against the surface of the wafer
16
. Unfortunately, because the polishing pressure produced by the fluid bearing typically cannot be controlled very well, the polishing pressure applied by the fluid bearing to different parts of the wafer
16
generally cannot be separately managed. Therefore, prior art fluid bearings generally do not accurately control wafer polishing on the leading and trailing edges of the wafer
16
.
FIG. 1C
shows a linear polishing apparatus
10
illustrating leading edge and trailing edge polishing pad deformations. In this example, a wafer
16
is attached to a carrier
18
and the carrier
18
by use of pressure
13
pushes the wafer
16
down on the polishing belt
12
that is moving in the direction
23
over the platen
24
. When the wafer contacts the polishing belt
12
, the polishing belt
12
deforms at a leading edge
16
a
and at a trailing edge
16
b
. A deformation
22
occurs at the leading edge
16
a
and a deformation
26
occurs at trailing edge
16
b
. The deformation
16
a
generally causes more polishing pressure on the leading edge
16
a
resulting in more material being removed. The deformation
16
b
generally causes less polishing pressure on the trailing edge
16
b
resulting in less material being removed. Consequently, due to the fact that the prior art polishing belt designs do not properly control polishing dynamics, uneven polishing and inconsistent wafer polishing may result thereby decreasing wafer yield and increasing wafer costs.
Therefore, there is a need for an apparatus that overcomes the problems of the prior art by having a platen that improves polishing pressure control and reduces polishing pad deformation.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing an apparatus for independently controlling the leading edge and the trailing edge of a wafer during CMP. The method involves utilizing an improved fluid bearing platen with strategically utilized fluid ports to powerfully control fluid pressure pushing on certain regions of the polishing pad. In this way, polishing pressure in different sections of a wafer may be separately controlled as well as polishing pad deformation during polishing. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, a platen assembly for supporting an underside of a linear polishing pad is disclosed. The platen assembly includes a platen surround plate, a platen interface assembly, and a platen manifold assembly. The platen manifold assembly is connected to the platen interface assembly, and the platen manifold assembly is supported by the platen surround plate. The platen manifold assembly includes a base plate, a gasket that fits on the base plate, an o-ring fitting around the platen, and a platen. The platen includes a plurality of separately controllable regions where each of the separately controllable regions is designed to communicate independent fluid flows through the separately controllable regions to the underside of the linear polishing pad.
In yet another embodiment, a platen for mounting under and supporting a linear polishing pad during chemical mechanical planarization (CMP) operations is disclosed. The platen includes a plate that has a plurality of separately controllable regions where each of the separately controllable regions is designed to communicate ind
Bahng Kenneth J.
Engdahl Erik H.
Gasparitsch Jeff
Stasiewicz Paul
Taff Robert
Lam Research Corporation
Martine & Penilla LLP
Rose Robert A.
LandOfFree
Apparatus for controlling leading edge and trailing edge... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for controlling leading edge and trailing edge..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for controlling leading edge and trailing edge... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3204562