Radiation imagery chemistry: process – composition – or product th – Plural exposure steps
Reexamination Certificate
1999-10-29
2003-01-14
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Plural exposure steps
C430S005000, C430S296000
Reexamination Certificate
active
06506544
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mask for transferring an illuminated pattern to a transfer area, and an exposure method and an exposure apparatus for transferring the pattern on the mask to a transfer area on a substrate. More specifically, the present invention relates to an exposure method and an exposure apparatus, and a mask suitable for pattern joining exposure at a transfer area on a substrate.
2. Description of the Related Art
In general, as an exposure apparatus for producing a liquid crystal display element or the like, there is one involving a so-called step and repeat method (stepper) in which after exposure of a pattern formed on a mask onto a predetermined exposure area on a photosensitive substrate, the photosensitive substrate is stepped by a certain distance, and exposure of the pattern of the mask is repeated.
Conventionally, when for example an LCD pattern for a liquid crystal display element having a large area is formed by the stepper, a screen synthesis method has been normally used.
With this screen synthesis method an LCD pattern in which a plurality of patterns are synthesized, is formed on a glass substrate using a plurality of masks corresponding to respective divided LCD patterns, by a method where after a pattern on a mask has been exposed onto an exposure area of the glass substrate corresponding to one mask, the glass substrate is stepped and the mask is changed to another mask, and a pattern on the mask is exposed onto an exposure area corresponding to that mask.
FIG. 38
is a pattern diagram in which a circuit pattern
1
of a glass substrate (substrate) P used at the time of production of a 15-inch liquid crystal display device is severally divided (into 6 in the figure).
The circuit pattern
1
has an approximate square shape, and comprises a display section
2
and a peripheral section
3
. The display section
2
comprises a pattern in which a plurality of electrodes corresponding to a plurality of pixels are disposed regularly. The peripheral section
3
is formed so as to surround the display section
2
, and has a conductive section for connecting a pattern of each electrode in the display section
2
to a driver circuit (not shown) for driving the respective electrodes. The circuit pattern
1
is constructed such that the circuit pattern is synthesized by divided patterns A to F including the display section
2
and the peripheral section
3
.
On the other hand,
FIG. 39
is a plan view of masks RA to RF on which patterns corresponding to these divided patterns A to F are formed. With a stepper using these masks RA to RF, for example, the mask RA is first attached, and a glass substrate P is shifted to a predetermined position corresponding to the divided pattern A and then exposed, to thereby transfer the divided pattern A onto the glass substrate P.
Then, the mask RA is changed to the mask RB, and the glass substrate P is shifted to a predetermined position corresponding to the divided pattern B and then exposed, to thereby transfer the divided pattern B onto the glass substrate P. The divided patterns A to F are transferred to the glass substrate P by repeating his operation sequentially.
Moreover,
FIG. 40
is a pattern diagram wherein a circuit pattern
4
of a glass substrate (substrate) P used at the time of production of a 21-inch liquid crystal display device is severally divided (into 15 in this figure). As described above, the circuit pattern
4
has such a construction as to be synthesized by divided patterns A to F
2
including the display section
2
and the peripheral section
3
. In this example, since a part of the display section
2
has a pattern where the divided patterns A, B and C are repeated, a plurality of shots are exposed with the same mask (for example, a mask having an A pattern).
FIG. 41
shows masks RA to RF in which patterns corresponding to these divided patterns A to F
2
are formed. Also in this case, as described above, by changing the masks sequentially, and shifting the glass substrate P to a predetermined position to thereby effect the exposure, the circuit pattern
4
is screen-synthesized.
When the above described screen synthesis method is performed, a difference in level occurs at a joint portion of the pattern due to a pattern rendering error of the mask, aberration of the lens of the projection optical system, positioning error of a stage where the glass substrate is to be stepped or the like, thereby impairing the properties of the device. Moreover, when the screen-synthesized divided patterns are overlapped in multiple layers, overlap error of the exposure area of each layer, and line width difference of the pattern change discontinuously at the joint portion of the patterns. Hence, to prevent the quality of the device from being degraded, a so-called pattern joining exposure is carried out.
This pattern joining exposure is to join and expose the joint portions in adjacent exposure areas, and in each exposure area, to proportionally reduce the exposure quantity (exposure energy quantity) in this joint portion toward the boundary by changing, for example, the exposure time, to thereby approximately match the exposure quantity in this portion with the exposure quantity in other portions, when the exposure is effected by overlapping the exposure areas. The pattern joining exposure is disclosed for example in Japanese Patent Application, First Publication Nos. Hei 6-244077 and Hei 7-235466.
However, the conventional exposure methods and exposure apparatuses and masks described above have the following problems.
Of the patterns formed on the respective masks RA to RF, the pattern in the display section
2
is such that a plurality of electrodes corresponding to pixels are regularly disposed. Therefore, even if the pattern is severally divided, a common alignment pattern partially exists in the respective divided patterns A to F.
With the divided patterns A to F however, the existence of the peripheral section
3
or the position to be connected by the peripheral section
3
is different, depending upon the position of the divided display section
2
. Therefore, even if there is a partially common pattern, masks RA to RF corresponding to the divided patterns A to F must be prepared, which imposes a big burden on the cost. Moreover, if the number of masks increases, the time required for changing the masks also increases, causing a problem in that improvement of throughput is hindered.
SUMMARY OF THE INVENTION
In view of the above situation, it is an object of the present invention to provide a mask, and an exposure method and an exposure apparatus using this mask, wherein when exposure processing accompanying screen synthesis is performed for producing a device, cost can be reduced and throughput improved by exposing only a small number of masks.
To achieve the above described object, the present invention adopts the following construction.
The exposure method of the present invention is an exposure method for joining and exposing a first pattern and a second pattern on a substrate using a mask having a pattern, wherein the pattern on the mask has a common pattern for the first pattern and the second pattern, and a non-common pattern different from the common pattern and formed continuously with the common pattern, and the common pattern and at least a part of the non-common pattern are selected to effect the joining and exposing.
Therefore, with the exposure method of the present invention, when the second pattern is subjected to the pattern joining exposure after the first pattern is exposed on the substrate, the common pattern common to the first pattern and at least a part of the non-common pattern different from the common pattern can be selected for use. Hence, at the time of exposure of the second pattern, there is no need to separately prepare a mask having the second pattern.
Moreover, with this exposure method, a pattern on the mask can be multiply transferred to a plurality of exposure areas with one mask so that the patterns be
Hori Kazuhiko
Iguchi Masahiro
Machino Katsuya
Toguchi Manabu
Huff Mark F.
Mohamedulla Saleha R.
Nikon Corporation
Oliff & Berridg,e PLC
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