Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Reexamination Certificate
1999-12-30
2001-10-23
Rosasco, S. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
C430S022000
Reexamination Certificate
active
06306548
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a micro device manufacturing method and an apparatus therefor, and in particular, to an exposure method and a substrate polishing apparatus in manufacturing micro devices such as semiconductor devices, liquid crystal display devices, etc.
2. Related Background Arts
In the case where micro devices such as semiconductor devices, liquid crystal display devices and the like are manufactured, there has usually been used an exposure apparatus which exposes a pattern formed on a reticle (or a photo mask and the like) onto a shot area on a wafer (or a glass plate and the like) on which a photosensitive material is applied. For this kind of exposure apparatus, an exposure apparatus of a so-called step-and-repeat type has been frequently used which repeat operations of sequentially exposing the pattern on the reticle onto the shot area on a wafer. Recently, there has been developed a projection exposure apparatus of a so-called step-and-scan type which exposes the pattern on the reticle onto an area wider than an exposure field of an projection optical system by scanning the reticle and the wafer at the same time.
Incidentally, since, a semiconductor device is, for example, produced by superimposing a plurality of layers of circuit patterns on the wafer, when circuit patterns of a second layer or a later layer are exposed on the wafer, alignment of each shot area of the wafer already formed with the circuit pattern with the pattern image of the reticle, that is alignment of the wafer with the reticle, must be precisely performed. For this purpose, there has been usually adopted a method wherein one or more wafer masks for alignment are formed on the wafer together with the reticle pattern and the wafer marks are used for aligning the circuit patterns of a subsequent layer.
There are several alignment sensors used for measuring the position of a wafer mark, which systems include an LSA (Laser Step Alignment) system which measures the position of a mark by irradiating a laser beam to a wafer mark on a wafer and detecting a diffracted and/or diffused light, an FIA (Field Image Alignment) system which measures the position of the wafer by image processing the wafer mark illuminated by a light emitted by a halogen lamp and having a wide wavelength band width, or an LIA (Laser Interferometric Alignment) system which measures the position of the wafer mark by irradiation with bi-directional laser beams, the frequencies of which are slightly different, causing two diffracted beams to interfere with each other and then detects the phase of the interfered beams. Of these systems, the LIA system conforms; to a flattening technique explained hereinafter, since it is most effective to detect the position of the wafer mark on the wafer which has a rough surface or a surface difference in level which is small.
Incidentally, the shape, number or size of the wafer mark for alignment is selected in correspondence with resolution of the projection optical system of the exposure apparatus, a required accuracy in alignment, a condition of the layer on the wafer, etc. There have usually been used many kinds of shapes, such as slit-like shape, dot-like shape or cross-like shape. However, in the past, most of these wafer marks have had relatively large recesses or concave portions; (having 4 &mgr;m width, 6 &mgr;m width and the like) and are formed with a concave and convex pattern, said pattern being periodically arranged between adjacent convex portions.
Multi-layer interconnection is a requisite of high integration and high densification as seen in a super LSI. In this technology, a technique for flattening the surface of a film or membrane of a predetermined layer is very important. This flattening technique is indispensable not only for realizing multi-layer interconnection but also for a process of producing an integrated circuit of the multi-layer structure. Such a flattening technique is usually performed by a chemical method such as an anodic oxidation method, a resin coating method, a glass flow method, an etch back method, a lift off method, a bias spatter method and the like. However, in addition to the above methods, a process (a chemical and mechanical polishing process) for chemically and mechanically polishing the surface of the film formed on the substrate by the above mentioned method is practiced as occasion demands.
A general structure of a substrate polishing apparatus for polishing the surface of a film on the substrate is shown in FIG.
12
. In
FIG. 12
, a wafer
124
is held by vacuum suction by means of a vacuum suction table
125
with a surface
124
a
(hereinafter referred to as pattern formation surface) on which a pattern layer and an upper layer film or membrane are formed. The wafer
124
held by vacuum suction on the vacuum suction table
125
is rotatable in the direction of rotation
300
B of a rotary table
136
, since the vacuum suction table
125
is placed on a rotary table
126
which can rotate in one direction.
A polishing surface plate
122
having a polishing pad
123
is disposed at a position that faces with the pattern formation surface
124
a
of the wafer
124
on the suction table
125
. The polishing pad
123
rocks or oscillater in the same direction as the movement of a rocking table
121
, since the polishing surface plate
122
is held by the rocking table
121
.
Moreover, a polishing agent supplying nozzle
127
for supplying a polishing agent to the pattern formation surface is provided. The polishing agent is supplied by the polishing agent supplying nozzle
127
between the pattern formation surface
124
a
and the polishing pad
123
, and at the same time at least one of the vacuum suction tables
125
and the polishing surface plate
122
moves upward and downward direction
300
A to cause the polishing pad
123
moving in response to rocking movement of the rocking table
121
and the wafer
124
rotating in response to the rotation of the rotary table
126
to contact, thereby polishing the pattern formation surface
124
a
(the upper most film formed on the upper layer of pattern layers) on the substrate
124
.
However, when the flattening process is performed by chemical and mechanical polishing, a phenomenon of so-called dishing which creates a dish-like concave portion or depression on the surface of the film or membrane results, if there is one or more concave portions or recesses having a width of not less than 2 &mgr;m on an under layer pattern of a metallic film or membrane which is beneath the film to be flattened. Accordingly, a same phenomenon such as stated above will occur on the surface of the membrane formed on a concave and convex pattern, if the wafer mark has relatively large concave portion (4 &mgr;m width, 6 &mgr;m width and the like) like a conventional wafer mark and if they are formed only by periodichally arranged concave and convex patterns. A state of the dishing is shown in FIGS.
8
(
a
) and
8
(
b
).
FIG.
8
(
a
) shows a state wherein an oxide film or membrane
92
is formed on a substrate
93
such as a wafer and recess or concave portion
90
a
has been formed in the oxide film by an etching, thereafter, a metallic coat
91
is formed on the oxide film by a spattering of aluminum. FIG.
8
(
b
) shows the state wherein said chemical and mechanical polishing is thereafter practiced on a product shown in FIG.
8
(
a
). In FIG.
8
(
b
) a dish-like portion D
1
is created by dishing above the concave portion
90
a
when the width of the concave portion
90
a
is not less than 2 &mgr;m. Dishing as shown in FIG.
8
(
b
) is caused when a pattern in which a plurality of concave portions or recesses
90
b
are periodically arranged is formed on a substrate and the metallic coat
91
is coated on the pattern. In this case, if a chemical and mechanical polishing is practiced on the coat, a large dish-like portion D
2
is created by dishing above the concave portions
90
b
as shown in FIG.
9
(
b
). Accordingly, when a wafer mark M includi
Mizutani Shinji
Ota Kazuya
Yasuda Masahiko
Armstrong Westerman Hattori McLeland & Naughton LLP
Nikon Corporation
Rosasco S.
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