Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – For liquid etchant
Reexamination Certificate
2000-03-13
2002-06-04
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
For liquid etchant
Reexamination Certificate
active
06398906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wafer transfer apparatus for delivering a wafer to be polished to a wafer holding head and for receiving a polished wafer from the wafer holding head. The present invention also relates to a wafer polishing apparatus to be used for an apparatus for polishing the surface of a semiconductor wafer, and a method for manufacturing the wafer.
The specification of the present invention is based on the Japanese Patent Applications (Japanese Patent Application Nos. 11-69336, 11-69337, 11-69338 and 11-35019), and the content of these Japanese applications are incorporated herein by references.
2. Description of the Related Art
Fine patterning of semiconductor wafers has been developed in recent years as a result of development of highly integrated semiconductor devices. Since fine patterning of the wafers having multilayer structures have been made easy and secure, it is particularly important to planarize the surface of semiconductor wafers as fine as possible in the manufacturing process. Finer planarization of the surface of the semiconductor wafers allows patterning precision to be improved besides making focusing of the exposed light easy when a photolithographic process is used for patterning. In addition, production of the semiconductor wafers can enjoy a low cost because the work efficiency is improved without providing complicated equipments for manufacturing the semiconductor wafers.
A chemical-mechanical polishing method (a CMP method) has been highlighted for this purpose since the method can polish the surface film with a high degree of planarity.
The surface of wafers are mechanically and chemically polished and planarized using an alkaline slurry containing SiO
2
, a neutral slurry containing SeO
2
, an acidic slurry containing Al
2
O
3
, or a slurry containing other abrasive (these are simply referred as a slurry hereinafter) in the CMP method. A wafer holding head for holding the wafer (a wafer holding head) and a polishing pad are usually disposed in opposed relation with each other in the wafer polishing apparatus for polishing the surface of the wafer, and the wafer is polished by allowing the wafer polishing head to rotate on the polishing pad by pressing the surface of the wafer onto the polishing pad while feeding a slurry.
Although it is desirable that the polishing pad is as planar as possible, its surface is deteriorated to cause decrease of polishing ability (polishing rate) by using it for polishing the wafer, or polishing performance (uniformity of polishing or degree of distribution of the thickness of the remaining film on the wafer) is decreased by causing a little roughness or inclination on the surface of the polishing pad, due to uneven abrasion or clogging of the pad after polishing. Therefore, the polishing pad is subjected to reforming (dressing) for restoring the polishing performance of the polishing pad, by allowing the polishing pad after finishing a wafer polishing process to rotates while allowing its surface to contact a dresser.
The polishing process may be simultaneously carried out with the dressing process as shown in
FIGS. 18 and 19
. In the first conventional example shown in
FIG. 18
, the wafer polishing apparatus
250
is provided with a wafer holding head
252
attached at the tip of an arm
251
supported to be able to freely pivot, a slurry feed means
253
for feeding a slurry to a polishing pad
256
, and a dresser
254
. The slurry feed device
253
directly feeds the slurry to the polishing pad
256
affixed on the surface of a platen
255
, and the wafer W held on the wafer holding head
252
is polished by allowing the wafer W to rotate while making contact with the surface of the polishing pad
256
. The dresser
254
is, on the other hand, held in rotatable manner with a driving mechanism
257
, which is supported on a base
258
. The base
258
is also supported to be linearly slidable along the direction indicated by an arrow Y with a guide member
259
. The dresser
254
dresses the surface of the polishing pad
256
that has a deteriorated polishing performance after polishing the wafer W. The wafer is polished at a different site from the site for dressing the wafer on the polishing pad
256
.
In the second conventional example shown in
FIG. 19
, the wafer polishing apparatus
300
is provided with three rotatable platens
301
and polishing pads
302
affixed on their surfaces, wafer holding heads
304
provided at the tips of respective two branched arms
303
, and dressers
306
that is able to linearly slide along a guide member
305
provided along the radial direction of each polishing pad
302
. The arm
303
is supported with a pivot
303
a
to be able to freely pivot, and the wafers supported with the wafer holding heads
304
are polished with respective polishing pads
302
. The surface of the polishing pad
302
is dressed with the dresser
306
that is slidable along the radial direction of the polishing pad
302
, while simultaneously polishing the wafer.
The third conventional example of the wafer polishing apparatus comprises an apparatus using a wafer holding head
350
as shown in FIG.
20
.
In
FIG. 20
, the wafer holding head
350
is provided with a head body
353
comprising a top plate
351
and a cylindrical circumference wall
352
fixed to the circumference of the top plate
351
, a diaphragm
354
expanded in the head body
353
and comprising an elastic material such as a rubber, a pressure adjustment mechanism
356
for adjusting the pressure in a fluid chamber
358
, a disk-shaped carrier
355
fixed on the lower face of the diaphragm
354
, and a ring-shaped retainer ring
357
disposed in concentric relation to the outer circumference of the carrier
355
.
The carrier
355
and the retainer ring
357
are fixed on a carrier fixing ring
359
and a retainer ring fixing ring
362
, respectively, provided on the upper face of the diaphragm
354
. The retainer ring
357
is disposed in concentric relation with a slight gap between the outer circumference face of the carrier
355
and the circumference wall
352
. The slight gap is provided for suppressing the displacement range of the retainer ring
357
along the radial direction from being too large due to elastic deformation of the diaphragm
354
.
The wafer W is affixed on a wafer affix sheet S (an insert) provided on the lower face of the carrier
355
, while the outer circumference of the wafer W being locked with the retainer ring
357
. The wafer is polished by allowing the wafer holding head
350
and the platen
361
to rotate causing a relative movement, when the slurry is fed onto the surface of the polishing pad
363
and the polishing face of the wafer W from outside of the wafer holding head
350
, while allowing the surface of the wafer W to contact the polishing pad
363
affixed on the upper face of the platen
361
.
The carrier
355
and the retainer ring
357
has a floating structure in which both members are able to independently displace along the ascending and descending directions by deformation of the diapliragm
354
. The pressing pressure of the carrier
355
and the retainer ring
357
onto the polishing pad
363
changes depending on the pressure in the fluid chamber
358
adjusted with pressure adjustment mechanism
356
.
While the wafer polishing apparatus as shown in the first and second conventional examples is effective for polishing the wafer, since the wafer polishing process and the dressing process can be simultaneously applied. However, when the wafer is polished with the wafer polishing apparatus as shown in the first conventional example, the slurry is directly fed onto the surface of the polishing pad
256
from outside of the wafer holding head
252
. Most of the fed slurry flows out by the centrifugal force applied to the rotating platen
255
, forcing to feed a large amount of the slurry for obtaining a sufficient polishing effect. A large amount of an expensive abrasive is wasted without effectively usin
Kajiwara Jiro
Kobayashi Tatsunori
Tanaka Hiroshi
MacArthur Sylviar
Mills Gregory
Mitsubishi Materials Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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