Abrading – Machine – Rotary tool
Reexamination Certificate
1999-03-01
2001-04-03
Rachuba, M. (Department: 3724)
Abrading
Machine
Rotary tool
C451S288000, C451S390000
Reexamination Certificate
active
06210260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a carrier and a chemical mechanical polishing (CMP) apparatus for uniformly polishing the surface of a rotating wafer or other workpiece while pressing the workpiece against a polishing pad of a platen.
2. Description of the Related Art
FIG. 15
is a sectional view of a carrier of a general CMP apparatus.
As shown in
FIG. 15
, a CMP apparatus is provided with a carrier
100
and with a platen
110
to which a polishing pad
111
is attached. By making the carrier
100
and the platen
110
rotate by a rotating mechanism while supplying a polishing solution in a state with the wafer W pressed against the platen
110
side by a carrier base
101
of the carrier
100
, the surface of the wafer W is polished by the polishing pad
111
.
Further, this CMP apparatus polishes the wafer W by the back side reference polishing system. Thus, a backing pad
102
is attached to the carrier base
101
and the surface of the wafer W is polished with the backing pad
102
in contact with the back surface of the wafer W.
Even if the sectional shapes of the backing pad
102
and the polishing pad
111
are uniform, there is sometimes warping or undulations in the wafer W itself. As opposed to this, the CMP apparatus shown in
FIG. 15
is not structured to deal with such warping or undulations in the wafer W, so it is not possible to uniformly press the surface of the wafer W as a whole.
Therefore, the carrier of the CMP apparatus of the air pressurizing system shown in
FIG. 16
has been devised.
A carrier
300
, as shown in the figure, provides a ring-shaped projecting portion
302
at the outer peripheral portion of the bottom surface of a carrier base
301
. By using a double-sided adhesive tape
304
to attach a backing pad
307
to the bottom surface of the projecting portion
302
, a pressure chamber
306
is defined.
In this configuration, air arriving through air holes in the carrier base
301
is introduced into the pressure chamber
306
to uniformly press the wafer W through the backing pad
307
by the air pressure in the pressure chamber
306
.
The above CMP apparatus of the related art, however, suffered from the following problems.
In the carrier
300
of the CMP apparatus according to the above related art, it is possible to press the entire surface of the wafer W by a uniform air pressure, but there was a large range of over polishing at the outer peripheral portion of the wafer W and the yield was remarkably poor.
FIG. 17
is an enlarged sectional view of the state of over polishing.
As shown in
FIG. 17
, this carrier
300
is structured with the wafer W covered by the backing pad
307
adhered to the projecting portion
302
of the carrier base
301
, so if a downward pressing force is applied to the carrier
300
during the polishing work, the outer peripheral portion of the backing pad
307
will be pulled downward by the projecting portion
302
.
Therefore, a tension T occurs at the outer peripheral portion of the backing pad
307
and a pressure of the vertical component T
1
of the tension T is applied to the outer peripheral portion of the wafer W in addition to the air pressure P.
As a result, the polishing rate of the outer peripheral portion of the wafer W becomes remarkably larger than the polishing rate of the other portions, the range of over polishing L becomes as larger as 10 mm to 20 mm, and the yield of the wafer W ends up becoming remarkably poor.
SUMMARY OF THE INVENTION
The present invention was made so as to solve the above problems and has as its object to provide a carrier and CMP apparatus which make uniform the distribution of pressure applied to the surface of the workpiece, including the outer peripheral portion, and improve the uniformity of polish of the entire surface of the workpiece.
Therefore, and according to a preferred embodiment of the presnt invention, there is provided a carrier comprising: a disk-shaped body portion having fluid circulation holes; a ring-shaped diaphragm portion expanding outward from the outer peripheral surface of the body portion and having pliability; a ring-shaped edge portion projecting at least downward from an outer edge portion of the diaphragm portion and having an inner diameter of at least an outer diameter of a workpiece; a pliable sheet having an outer peripheral portion affixed air-tightly to a bottom end portion of the edge portion and defining a pressure chamber communicating with the fluid circulation holes; and a ring-shaped member surrounding the workpiece affixed to the bottom surface of the sheet.
In this configuration, if the body portion is pressed in a state where the workpiece on the platen is held by the ring-shaped member of the carrier, the sheet contacts substantially the entire surface, essentially molding itself to the warping etc. of the workpiece. If fluid of a predetermined pressure is supplied from the fluid circulation holes of the body portion in this state, the fluid will pass through the fluid circulation holes of the body portion and fill the pressure chamber and substantially the entire surface of the workpiece will receive a uniform fluid pressure through the sheet.
If the body portion of the carrier is pressed, however, the downward pressing force will be transmitted to the edge portion as well and the edge portion will act to pull the outer peripheral portion of the sheet downward. Since the edge portion is connected to the body portion through the pliable diaphragm portion, however, the pliable diaphragm portion will flex and the pressing force applied to the edge portion will be relieved. Therefore, no downward tension will occur at the outer peripheral portion of the sheet and the distribution of pressure of the fluid acting on the entire surface of the workpiece will become uniform.
Further, since the workpiece is surrounded by the ring-shaped member, the workpiece will not jump outside when the carrier is rotating.
For a sheet, it is possible to use various types of pliable sheets. According to a preferred embodiment of the invention, the sheet is formed by a single hard or soft sheet and the outer peripheral portion of the upper surface of the hard or soft sheet is affixed air-tightly to the bottom surface of the edge portion by an insoluble adhesive or soluble adhesive.
Further, according to another embodiment of the invention, a soft sheet is adhered to the bottom surface of a hard sheet.
Further, according to yet another embodiment of the invention, the hard and the soft sheets are adhered through an intermediate sheet having an adhesive on its upper and lower surfaces.
If a fluid is supplied inside the rotating air-tight pressure chamber, however, the fluid pressure at the outer peripheral portion of the pressure chamber may differ from the fluid pressure at other portions. Therefore, according to another embodiment of the invention, the edge portion is provided with through holes communicating the pressure chamber and the outer portion.
In this configuration, the fluid flowing from the fluid circulation holes into the pressure chamber flows out from the through holes to the outside, the flow of the fluid in the pressure chamber is stabilized, and the uniformity of distribution of pressure is further improved.
Further, according to another embodiment of the invention, the diaphragm portion at locations near the edge portion is provided with holes communicating the pressure chamber and an outer portion.
CMP apparatuses using the carrier also stand as aspects of the invention in their own right. Therefore, according to another embodiment of the invention, there is provided a CMP apparatus provided with a platen to the surface of which a polishing pad is attached, a carrier capable of rotating in a state where the workpiece on the polishing pad of the platen is held, a fluid supply means capable of supplying fluid of a desired pressure to the carrier, and a rotary drive means for rotating the carrier while pressing against it, wherein the carrier is comprised of a disk-shaped body p
Hakomori Shunji
Ishida Makoto
Sugiyama Misuo
Tanaka Hideo
Tanaka Kei
Burr & Brown
Rachuba M.
Speedfam Co., Ltd.
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