Abrading – Accessory – Dressing
Reexamination Certificate
2000-03-08
2002-08-27
Eley, Timothy V. (Department: 3723)
Abrading
Accessory
Dressing
C451S548000
Reexamination Certificate
active
06439986
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a conditioner for polishing pad and a method for manufacturing the same, and more particularly to a conditioner for polishing pad to be used in chemical mechanical polishing (CMP) process and a method for manufacturing the same.
2. Description of the Prior Art
Generally, chemical mechanical polishing is widely used in the manufacturing process of semiconductor devices to obtain smooth and even surfaced wafers. Typically, a wafer to be polished is held by a carrier positioned on a polishing pad attached above a rotating platen (not shown), then by applying slurry to the pad and pressure to the carrier, the wafer is polished by relative movements of the platen and the carrier. A conventional polishing pad used for chemical mechanical polishing process generally comprises a multitude of fine holes having a diameter size of 30-70 &mgr;m for exhibiting pumping-effect when pressure is applied to the polishing pad to achieve a high removal rate. However, after a prolonged use, the holes wear out and become deposited with polishing residues, causing an uneven surface of the polishing pad. As a result, its ability to polish wafers decreases in time and the effectiveness of CMP process of achieving an uniformly even wafer surface becomes diminished.
To recover the polishing performance and to compensate for the uneven surface of the polishing pad, conditioning process utilizing a conditioner for removing the uneven surface of the polishing pads is commonly implemented by CMP protest.
FIGS. 1A
to
1
C show a structure of a diamond conditioner used for conditioning polishing pads, which is manufactured by conventional electro-deposition method. Such diamond conditioner is typically made from an electro-plated diamond disk in which diamond particles
16
are scattered onto a stainless steel body portion
10
and electro-deposited by bonding metal
18
such as nickel or made from a brazed diamond disk in which the diamond particles
16
are fixed onto the body portion
10
by melting the bonding metal
18
.
However, the conditioners made from such electro-deposition and braze methods have cutting surfaces of an uneven height caused by irregular distribution and varying sizes of the diamond particles
16
as illustrated by a cutting portion
12
in FIG.
1
C. Particularly, having diamond particles with diameter size beyond the range of 150-250 &mgr;m in the conditioner cutting surface causes an undesirable surface roughness.
Further, because the conditioners having the above structure polishes wafers by making partial point contact and due to obtuse cutting angles of diamond particles, the cutting efficiency obtained by such conditioners is low. As such, in order to improve the cutting efficiency, it is necessary to apply high pressure in the conventional conditioning processes. In conventional polishing pads having a dual-pad structure commonly made from polyurethane material, CMP is carried out in top pad while bottom pad provides pressure required for the conditioning process. When high pressure is applied to the top pad by conditioner during the conditioning process, due to the compressibility of the bottom pad, the conditioning cannot be smoothly carried out. Thus, maintaining a flat and leveled polishing pad surface becomes a difficult task.
More, the conditioners made from electro-deposition and brazed methods does not provides grooves or ditches for draining particles from the polishing pads. As a result, residual particles deposit and accumulate on the conditioner surface, which further attributes to decreasing the conditioning effectiveness.
Conventionally, the conditioning process can be carried out simultaneously with CMP process. Such in-situ conditioning process are classified into oxide or metal CMP processes by the type of slurry used for the polishing process, which is typically constituted by silica, alumina or ceria polishing materials. The slurry used for oxide CMP generally has a pH value with 10-12, while the slurry used for metal CMP has a pH value less than 4, and the bonding metal
18
used for fixing the diamond particles
16
onto the cutting surface of the conditioner is nickel, chromium or the like metals. In implementing either oxide or metal CMP in-situ conditioning process, because the polishing process is simultaneously carried out with conditioning process, the bonding metal
18
holding the diamond particles
16
is also affected by slurry, resulting in frequent detachments of the diamond particles
16
from the conditioner surface. Further, in metal CMP in-situ conditioning process, the strong acid property of the slurry used for the process has a tendency to corrode the bonding metal
18
to weaken its bonding effect, which ultimately causes the detachments of the diamond particles
16
.
The detached diamond particles
18
usually attach to the surface of the polishing pads and impart fatal scratches to the wafer surface during the polishing process to cause high defective rates in the semiconductor manufacturing process. Consequently, the polishing pads must be frequently replaced.
Further, metal ions from the eroded bonding metal
18
in metal CMP in-situ conditioning process often attaches to metal lines of the wafer circuits to causes short-circuits. In addition, metal ions from the in-situ conditioning process substantially attributes to the metal ion contamination of the wafers, and because the resulting semiconductor defects caused by the contamination are detected at the later manufacturing stages, its impact in the loss incurred from the defects is considerable in the industry.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a conditioner for polishing pad which has an excellent and uniform degree of surface roughness for preventing defects caused from the detachments of diamond particles and metal ion contamination and for effectively conditioning the polishing pads in absence of high pressure in chemical mechanically-polishing process for the semiconductor wafers.
It is a second object of the present invention to provide a method for manufacturing a conditioner for polishing pad which has the characteristics and functions of the above described conditioner.
According to the present invention, there is provided a conditioner for polishing pad comprises a substrate having integrally formed with a plurality of geometrical protrusions in an uniformed height on at least one side of the substrate and a diamond layer of an uniformed thickness formed substantially on a whole surface of the substrate side having geometrical protrusions.
It is preferred that the above geometrical protrusions have rectangular or cylindrical shapes and have flat and even upper surfaces. Optionally, the upper surfaces of the geometrical protrusions can have a plurality of smaller geometrical protrusions formed by a pair of diagonally-crossed grooves having U or V cross-sectional shapes or by a number of crossed-strips of grooves having U or V cross-sectional shapes. The smaller geometrical protrusions formed on the upper surfaces of the geometrical protrusions have a plane view shape of triangle, rectangle or rectangular pyramid.
The plurality of geometrical protrusions integrally formed on the surface of the substrate has a crossed-strip pattern realized by crossing-strips of ditches having U or V cross-sectional shapes, where the U or V cross-sectional shapes are defined by a side portion of the geometrical protrusions and a bottom portion of the ditches. The crossing-strips of ditches all have same width and or depth, or alternatively a ditch having a greater width and or depth can be formed at an interval of a certain number of ditches on the crossed-strip pattern as a region dividing ditch.
The substrate is not limited by any shapes as long as a plurality of geometrical protrusions can be realized on its surface. For example, the substrate can have a shape of a disk, a doughnut or a plate having multiple corners, or on one side
Myoung Bum Young
Yu Su Nam
Hunatech Co., Ltd.
Nguyen Dung Van
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