Abrading – Abrading process – With tool treating or forming
Reexamination Certificate
2002-06-26
2003-12-23
Wilson, Lee D. (Department: 3723)
Abrading
Abrading process
With tool treating or forming
C451S288000, C451S285000, C451S296000, C451S533000
Reexamination Certificate
active
06666755
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to chemical mechanical planarization (CMP) methods and systems, and more particularly, to a belt wiper for removing fluid and particulate material that can interfere with a CMP process.
2. Description of the Related Art
In the fabrication of semiconductor devices, planarization operations on silicon wafers, which can include planarizing, polishing, buffing, and cleaning, are often performed. Typically, integrated circuit devices are in the form of multi-level structures on silicon substrate wafers. At the substrate level, transistor devices with 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. 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 and metal layers increases. Without planarization, fabrication of additional metallization layers becomes substantially more difficult due to the higher variations in the surface topography.
Planarizing metallization layers is becoming more important due to replacement of aluminum with copper as the metal of choice for metallization processes. One method for achieving semiconductor wafer planarization is the chemical mechanical planarization (CMP) technique. Further applications include planarization of dielectric films deposited prior to the metallization process, such as dielectrics used for shallow trench isolation or for poly-metal insulation. CMP systems typically implement a rotary, an orbital, or a linear pad system in which a preparation surface of a polishing pad is used to polish one side of a wafer. In general, the CMP process involves applying a controlled pressure to a typically rotating wafer that is in contact with a moving polishing pad coupled with a slurry containing a mixture of abrasive materials and chemicals to facilitate the planarization process. Slurry is most usually introduced onto a moving preparation surface and distributed over the preparation surface as well as the surface of the semiconductor wafer being prepared by the CMP process. The distribution of the slurry is generally accomplished by a combination of the movement of the preparation surface, the movement of the semiconductor wafer and the fluid dynamics between the semiconductor wafer and the preparation surface.
FIG. 1
shows a conventional linear belt-type CMP system
100
. The conventional linear belt-type CMP system
100
includes a polishing head
108
, also known as a wafer carrier, which secures and holds a wafer
104
in place during CMP processing. A belt pad
102
, also known as a linear polishing belt, is disposed in the form of a band around rotating drums
112
. The belt pad
102
is composed of materials that provide structural integrity and facilitate the planarization/polishing of the CMP process. The belt pad
102
moves in a direction
106
at a speed of up to approximately 1000 feet per minute; however, this speed may vary depending upon the specific CMP process. As the belt pad
102
moves, the polishing head
108
rotates and lowers the wafer
104
onto the top surface (i.e., the preparation surface) of the belt pad
102
. The wafer
104
is applied to the belt pad
102
with a force
118
sufficient to facilitate the CMP process.
A fluid bearing platen manifold assembly
110
supports the belt pad
102
during the CMP process. Typically, the fluid bearing platen manifold assembly
110
utilizes a pressurized gas bearing. The pressurized gas bearing, typically composed of clean dry air, is provided by a gas source
114
and is input through the fluid bearing platen manifold assembly
110
via several independently controlled dispersion holes. The pressurized gas bearing provides upward force on the belt pad
102
to control the profile of the belt pad
102
.
A slurry
122
is delivered to the belt pad
102
by a slurry manifold
120
including many nozzles. The slurry manifold
120
dispenses the slurry
122
on the top surface of the belt pad
102
. Movement of the belt pad
102
in the direction
106
transports slurry
122
underneath the wafer
104
. The slurry manifold
120
is typically aligned in a position relative to the wafer
104
such as center on the wafer
104
. However, the position of the slurry manifold
120
can be adjusted to somewhat optimize the uniformity of the removal of material from the surface of the wafer
104
.
A pre-wet manifold
124
containing a number of dispersion holes
126
is positioned at a leading edge of a platen assembly
135
, where the leading edge is defined relative to the belt pad
102
movement direction
106
. A fluid, typically deionized water, flows through the dispersion holes
126
of the pre-wet manifold
124
to provide both rinsing and lubrication of the underside of the belt pad
102
and the fluid bearing platen manifold assembly
110
. Prior to reaching the pre-wet manifold
124
, the edge of the belt pad
102
passes by a belt-tracking sensor
128
. The belt-tracking sensor
128
is used to sense the position of the belt pad
102
edge so that the belt pad
102
can be steered accurately while traveling around the rotating drums
112
in the direction
106
.
FIG. 2
shows a top view of the platen assembly
135
. The platen assembly
135
includes the fluid bearing platen manifold assembly
110
. Pressurized gas flows out of a number of dispersion holes
136
to provide support and lubrication to the belt pad
102
as it traverses the platen assembly
135
. Also, a platen optics window
130
is located at the center of the fluid bearing platen manifold assembly
110
. The platen optics window
130
is a component of an endpoint detection system which measures a wafer film thickness and signals when the CMP process is finished. The pre-wet manifold
124
containing the number of dispersion holes
126
is also shown attached to the leading edge of the platen assembly
135
with respect to the belt pad
102
direction
106
.
FIG. 3
shows a top view of the belt pad
102
traversing the pre-wet manifold
124
and the platen assembly
135
in the direction
106
. The belt pad
102
contains a belt window
132
which passes over the platen optics window
130
as the belt pad
102
traverses the platen assembly
135
. The belt-tracking sensor
128
is also shown in relation to the belt pad
102
edge and platen assembly
135
. By monitoring a distance across a region
134
between the belt-tracking sensor
128
and the belt pad
102
edge, the belt pad
102
can be accurately steered as it travels around the rotating drums
112
.
The belt-tracking sensor
128
operates based on sound wave propagation and detection. The belt-tracking sensor
128
generates and directs sound waves toward the belt pad
102
edge. The sound waves are reflected back from the belt pad
102
edge to the belt-tracking sensor
128
where they are detected. A propagation time required for the sound waves to travel to the edge of the belt pad
102
and return to the belt-tracking sensor
128
is used to accurately determine the position of the belt pad
102
edge. The sound wave propagation time can be affected by variations in the region
134
through which the sound wave travels. Normally, the belt pad
102
edge position is determined using the sound wave propagation time and assumptions regarding the prevailing characteristics of the region
134
between the belt-tracking sensor
128
and the belt pad
102
edge. During a CMP process, air from the fluid bearing platen manifold assembly
110
blows through both the fluid provided by the pre-wet manifold
124
and any excess slurry
122
on the underside of the belt pad
102
resulting in a disturbance of the region
134
between the belt-tracking sensor
128
and the belt pad
102
edge. The air, fluid, and slurry
122
disturbance causes a
DiPietro Christian
Jew Stephen
Luong Tony
Ngoon Philip
Ramanujam Katgenahalli Y.
Lam Research Corporation
Martine & Penilla LLP
Wilson Lee D.
LandOfFree
Belt wiper for a chemical mechanical planarization system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Belt wiper for a chemical mechanical planarization system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Belt wiper for a chemical mechanical planarization system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3103030