Abrading – Flexible-member tool – per se
Reexamination Certificate
2000-12-27
2003-05-13
Nguyen, George (Department: 3723)
Abrading
Flexible-member tool, per se
C451S533000
Reexamination Certificate
active
06561889
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to chemical mechanical polishing (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 polishing (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 metallization.
A chemical mechanical polishing (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
in the prior art, 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
. Typically, the polishing belt
12
has seams
14
in different sections of the polishing belt
12
.
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
. 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 supporting layer is generally made from a firm material such as stainless steel. 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, an air 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 air against the under surface of the supporting layer. The applied air thus forms an controllable air bearing that assists in controlling the pressure at which the polishing belt
12
is applied against the surface of the wafer
16
. As mentioned, seams
14
of the polishing belt
12
are generally located in several different locations in the polishing belt
12
. Therefore, the polishing belt is made up of multiple sheets of a polymer material that are connected together by, for example, an adhesive, stitching, or the like to form a continuous belt. A seam section
30
illustrates one of the seams
14
, which will be discussed in greater detail in FIG.
1
C. Therefore, during a CMP process, moisture from, for example, slurry may intrude into the inner portion of the polishing belt
12
through the seams
14
. The moisture may then attack the adhesive holding the polishing belt and the supporting layer together thus causing delamination of the polishing belt from the supporting layer. Therefore, the prior art designs have serious delamination problems due to moisture intrusion into the seams
14
. In addition, shear forces created between the support layer and the polishing belt
12
when moving over the rollers
20
can be a very serious destructive factor and also cause delamination. As a result, the life of the polishing belt may be shortened significantly. Such a shortening of polishing belt life may then cause a considerable decrease in wafer production. This problem is further described in reference to FIG.
1
C.
FIG. 1C
shows a magnified view of an exemplary seam section
30
after delamination has started to take place. The seam section
30
includes a seam
38
, a polymer polishing layer
32
connected on top of a supporting layer
36
by an adhesive
42
. Delaminations
40
start to occur between the polymer polishing layer
32
and the supporting layer
36
as the fluids start to attack the integrity of the adhesive material, and thus, the adhesive
42
will either itself start to come off of the supporting layer
36
and/or allow the polishing layer
32
to delaminate progressively as critical CMP operations are in progress. Additionally, when the polymer polishing layer
32
and the supporting layer
42
move over the rollers
20
(as shown in reference to FIG.
1
C), shear forces may be created causing serious delaminatory damage.
During a CUT process, slurry is typically applied to the polishing belt
12
of
FIGS. 1A and 1B
. When this occurs, the moisture from the slurry may seep through the seam
38
. In more detail, the delaminations
40
tend to form after continued use of a polishing belt because of the moisture seepage from a surface of the polishing belt down the seam
38
to the adhesive film
42
. The moisture seepage can then break down the adhesive film
42
. When this occurs, the different layers
32
and
36
of the polishing belt
12
may start to peel off, as described above, due to the loss in adhesion resulting in the delaminations
40
. In addition, pressures and shear forces exerted on the polishing belt during the CMP process can serve to exacerbate matters and can greatly increase the creation of the delaminations
40
. When the seam section
30
moves over rollers, the support layer
36
does not stretch very much thus defining a neutral axis. The polishing belt
12
on top of the supporting layer
36
typically stretches when it is bending over the roller because outer layers tend to stretch more than inner layers. When the seam section
30
is no longer on the rollers, the stretch disappears and the seam section
30
c
Dai Fen
Xu Cangshan
Zhao Eugene Y.
Lam Research Corporation
Martine & Penilla LLP
Nguyen Dung Van
Nguyen George
LandOfFree
Methods for making reinforced wafer polishing pads and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods for making reinforced wafer polishing pads and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods for making reinforced wafer polishing pads and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3051807