Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – For liquid etchant
Reexamination Certificate
2001-05-18
2004-06-15
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
For liquid etchant
Reexamination Certificate
active
06749714
ABSTRACT:
This application is filed under 35 U.S.C. §371 from International Application PCT/JP00/01544, with an international filing date of Mar. 14, 2000, which claims the benefit of priority to Japanese Application Nos.: 11-88157, filed Mar. 30, 1999; 11-98179, filed Apr. 5, 1999; 11-254941, filed Sep. 8, 1999; 2000-25373, filed Feb. 2, 2000; and, 2000-25386, filed Feb. 2, 2000, which are incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polishing body used in a polishing apparatus which is suitable for use in planarization polishing, etc., of semiconductor devices such as ULSI devices, etc., performed in processes in which such semiconductor devices are manufactured, a polishing apparatus and a polishing method, and further relates to a semiconductor device manufacturing method using the above-mentioned polishing apparatus and polishing method.
2. Discussion of the Related Art
As semiconductor integrated circuits have become finer and more highly integrated, the individual processes involved in semiconductor manufacturing processes have become more numerous and complicated. As a result, the surfaces of semiconductor devices are not always flat. The presence of step differences on the surfaces of semiconductor devices leads to step breakage of wiring and local increases in resistance, etc., and thus causes wiring interruptions and drops in electrical capacitance. In insulating films, furthermore, such step differences also lead to a deterioration in the withstand voltage and the occurrence of leaks.
Meanwhile, as semiconductor integrated circuits have become finer and more highly integrated, the wavelengths of light sources in semiconductor exposure apparatuses used in photolithography have become shorter, and the numerical aperture or so-called NA of the projection lenses used in such semiconductor exposure apparatuses has become larger. As a result, the focal depth of the projection lenses used in such semiconductor exposure apparatuses has become substantially shallower. In order to deal with such increasing shallowness of the focal depth, there is a demand for even greater planarization of the surfaces of semiconductor devices than that achieved so far.
To describe this in concrete terms, planarization techniques such as that shown in
FIG. 1
have become essential in semiconductor manufacturing processes.
FIG. 1
is a schematic diagram illustrating planarization techniques used in a semiconductor manufacturing process, and shows sectional views of a semiconductor device. In
FIG. 1
,
11
indicates a silicon wafer,
12
indicates an inter-layer insulating film comprising SiO
2
,
13
indicates a metal film comprising Al, and
14
indicates the semiconductor device.
FIG. 1A
shows an example of the planarization of an inter-layer insulating film
12
on the surface of the semiconductor device.
FIG. 1B
shows an example in which a so-called damascene is formed by polishing a metal film
13
on the surface of the semiconductor device. A chemical mechanical polishing or chemical mechanical planarization (hereafter referred to as “CMP”) technique is widely used as a method for planarizing the surfaces of such semiconductor devices. Currently, the CMP technique is the sole method that can be used to planarize the entire surface of a silicon wafer.
CMP was developed on the basis of silicon wafer mirror surface polishing methods, and is performed using a CMP apparatus of the type shown in FIG.
2
. In
FIG. 2
,
15
indicates a polishing member,
16
indicates a member that holds the object of polishing (hereafter referred to as a “polishing head” in some instances),
17
indicates a silicon wafer which is the object of polishing,
18
indicates a polishing agent supply part, and
19
indicates a polishing agent. The polishing member
15
has a polishing body
21
(hereafter referred to as a “polishing pad” in some instances) which is attached to the surface of a polishing platen
20
. A sheet-form foam polyurethane is widely used as such a polishing body
21
.
The object of polishing
17
is held by the polishing head
16
, so that it is caused to oscillate while being rotated, and is pressed against the polishing body
21
of the polishing member
15
with a specified pressure. The polishing member
15
is also rotated, so that a relative motion is performed between the polishing member
15
and the object of polishing
17
. In this state, the polishing agent
19
is supplied to the surface of the polishing body
21
from the polishing agent supply part
18
. The polishing agent
19
diffuses over the surface of the polishing body
21
, and enters the space between the polishing body
21
and the object of polishing
17
as the polishing member
15
and object of polishing
17
move relative to each other, so that the surface of the object of polishing
17
that is to be polished is polished. Specifically, good polishing is accomplished by a synergistic effect of the mechanical polishing caused by the relative motion of the polishing member
15
and object of polishing
17
and the chemical action of the polishing agent
19
.
In cases where a sheet-form polishing pad comprising a conventional foam resin (hereafter referred to as a “foam polishing pad”) is used, the uniformity of the polishing over the entire surface of the wafer is good. However, foam polishing pads generally suffer from the following problems:
(1) The edge sloping that occurs in polishing is great.
(2) When a load is applied, the pads undergo compressive deformation.
As a result of these problems, foam polishing pads have not shown good step difference elimination characteristics, i.e., good polishing smoothness, in the case of patterned wafers. Recently, therefore, polishing pads comprising harder non-foam resins (hereafter referred to as “non-foam polishing pads” in some instances) have been investigated.
In non-foam polishing pads, indentations and projections comprising a groove structure are formed in the surface of a hard macromolecular polymer, and these indentations and projections polish the surface of the object of polishing (in this case, a wafer). The use of a non-foam polishing pad solves the problem of poor step difference elimination characteristics encountered in cases where foam polishing pads are used.
In regard to the process stability of a CMP apparatus, an absence of scratches is required from the standpoint of avoiding wiring interruption and insulation breakdown of the device, in addition to the requirement for stable uniformity and smoothness even when the number of wafers treated by the polishing pad is increased.
However, although hard polishing pads comprising non-foam resins show good pattern step difference elimination, such pads tend to cause scratching of the wafer; furthermore, the polishing rate tends to be lower than that of polishing pads comprising a foam polyurethane.
Furthermore, other important factors that generally determine the polishing rate of a polishing pad include the retention and fluidity of the polishing agent on the surface of the polishing pad. In terms of retention of the polishing agent, hard non-foam polishing pads cannot match foam polishing pads. Furthermore, in cases where conventional non-foam polishing pads are fastened to the surface of a platen, and this platen is rotated at a high speed while the polishing agent is supplied, the polishing agent is caused to fly off the polishing pad by centrifugal force, so that the polishing agent retention is low. Accordingly, there is a problem in that the polishing agent that is supplied does not effectively contribute to an increase in the polishing rate.
Meanwhile, the most commonly used polishing body in conventional processes is a polishing body (polishing pad) which chiefly comprises a foam polyurethane. Such a polishing body has a superior capacity for retaining the polishing agent on the surface of the polishing body. However, when such a polishing body is continuously used, the abrasive particles of the polishing agent clog t
Ishikawa Akira
Senga Tatsuya
MacArthur Sylvia R.
Mills Gregory
Morgan & Lewis & Bockius, LLP
Nikon Corporation
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