Photocopying – Projection printing and copying cameras – Illumination systems or details
Reexamination Certificate
1999-06-16
2002-03-12
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Illumination systems or details
C355S077000, C430S311000
Reexamination Certificate
active
06356341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to exposure devices which are used for manufacturing of semiconductor components and liquid crystal display substrates, for example, by projecting patterns of reticles, to which light sources radiate beams by illuminating area setting means, on photosensitive substrates, and particularly relates to exposure devices, used to perform so-called screen composition in which parts of patterns overlap each other on the photosensitive substrates to form patterns of large areas, as well as devices usable for the exposure devices such as beam shape setting devices, which adjust shapes of beams from illumination sources, and illuminating area setting devices.
2. Background Art
Conventionally, in order to cope with enlargement of the photosensitive substrates which serve as exposed objects, the exposure device of this kind employs a method of screen composition in which an overall exposed area of the photosensitive substrate is divided into multiple unit areas and exposure is repeated in response to each of the unit areas so that desired patterns are formed. In order to perform the screen composition, exposure is performed on exposed areas whose boundaries slightly overlap each other in order to prevent gaps from being formed at boundary positions of the exposed areas due to formation errors of reticles used for pattern projection, aberrations of optical lenses for projection, and errors in positioning of stages used for positioning of the photosensitive substrates.
In general, adjustment of the aforementioned illuminating areas is performed such that reticle blinds are arranged at substantially conjugate positions of the reticles within an optical system of illumination illuminating the reticles. The reticle blind of this kind corresponds to opposed arrangement of units (hereinafter, referred to as blind blades) having two reference sides which are made of metal materials crossing each other, so that openings are set in positions and sizes, that is, illuminating areas are set by moving the blind blades in X-Y directions that cross an optical axis.
However, if such reticle blinds are used and are simply overlapped with the exposed areas, exposure values are doubled with respect to overlapped portions, so some characteristic of photosensitizer may causes variations in line widths of patterns at their joint portions. In addition, when the screen composition is performed, differences in level are caused to occur at the joint portions of the patterns due to positional gaps between the adjoining exposed areas, which may damage characteristics of devices.
In the case where different exposure devices share steps of multilayer composition using patterns of a single layer formed by screen composition with respect to multiple layers respectively, overlapping errors in overlapping the exposed areas of the layers vary discontinuously at joint portions of the patterns due to lens aberrations and positioning accuracy of the exposure devices, wherein particularly in active-matrix liquid crystal display devices, contrasts vary discontinuously at the joint portions of the patterns, so qualities of the devices will be deteriorated.
Therefore, in order to eliminate the aforementioned disadvantages in the screen composition, an exposure device disclosed by Japanese Patent Application, First Publication No. Hei 7-235466 is proposed. In this exposure device, there is arranged a reticle blind
5
, which is formed by overlapping two sheets of blinds
5
A,
5
B as shown in
FIG. 10A
at optically conjugate positions with respect to the reticle, wherein it is possible to obtain a pattern of a necessary extinction area by matching openings
23
,
25
of the blinds
5
A,
5
B together, further, it is possible to match an irradiation range of illumination light with a size of the reticle by changing sizes of the openings, which is actualized by changing relative positions of the blinds
5
A,
5
B.
The reticle blind
5
is formed by arranging the blinds
5
A,
5
B, each of which has two openings and whose chrome surfaces face with each other, in proximity to each other in an order of 100 &mgr;m. In addition, each of the blinds
5
A,
5
B is formed by vapor deposition in which chrome is deposited on a transparent glass substrate and is equipped with a shade portion
21
for shade of illumination light, extinction portions
22
,
24
for attenuation of transmission factors of illumination light and openings
23
,
25
on which chrome is not deposited.
In the extinction portions
22
,
24
, a chrome film corresponds to dots, each of which is smaller than a resolution limit of the exposure device, and are deposited on the glass substrate, wherein a density of the dots of the chrome film is increased in a direction from the opening
23
to the shade portion
21
(or from the opening
25
to the shade portion
21
) so that an extinction factor is changed with respect to the extinction portion
22
or
24
. FIG.
10
B and
FIG. 10C
show extinction characteristics with respect to one blind
5
A or
5
B of the reticle blind
5
. By overlapping adjoining exposed areas in the extinction portions
22
,
24
, the joint portions of the patterns change smoothly.
However, the aforementioned reticle blind
5
requires the transparent substrate like the glass as the base for formation of the extinction portions
22
,
24
, so if particles whose diameters are greater than a certain diameter are adhered to the glass substrate of the reticle blind
5
at its openings
23
,
25
or extinction portions
22
,
24
, there is a problem that the particles originally adhered on the glass substrate of the reticle blind
5
are transferred to the photosensitive substrate because the reticle blind
5
, reticle and photosensitive substrate are arranged at optically conjugate positions.
For this reason, the conventional device is equipped with a particle detector which detects adhesion of the particles by projecting detection light such as mercury light on Cr-deposited surfaces and measuring amounts of scattering light which occurs, so the construction of the device must be complicated.
In addition, the aforementioned particle detector is capable of performing detection on a front surface of a glass plate but is hard to project the detection light on a back of the glass plate due to construction thereof, so it is actually incapable of detecting existence of foreign matters to be existed on the back of the glass plate.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the aforementioned problems, and it is an object of the invention to provide an exposure device, which is capable of preventing particles from being transferred to a photosensitive substrate and which does not require a particle detector, as well as a beam shape setting device used for the exposure device.
In order to achieve the aforementioned object, an exposure device of the present invention, which has an illumination optical system for illuminating a reticle having a pattern with a beam from an illumination source so that the pattern is formed on a substrate on exposure to light, is equipped with illuminating area setting means, which are arranged at two locations in the illumination optical system so as to set an illuminating area of the beam illuminating the reticle, and an optical system which places the illuminating area setting means being conjugate to the reticle.
In addition, a beam shape setting device of the present invention, which has a transmission portion for transmitting a beam therethrough and a shade portion for shade of the beam so as to set a shape of the beam, is equipped with a protection member which covers the transmission portion with a material that transmits the beam.
The beam shape setting device of the present invention can be equipped with an extinction portion, which is arranged in at least a part of an area between the transmission portion and the shade portion and which reduces a transmission factor of the beam to be smaller in a direction fro
Hanazaki Noritsugu
Murakami Masaichi
Takemura Norimi
Nguyen Henry Hung
Nikon Corporation
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