X-ray or gamma ray systems or devices – Specific application – Lithography
Reexamination Certificate
2000-06-09
2002-10-08
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Lithography
Reexamination Certificate
active
06463119
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an exposure method and an exposure device, which is particularly suitable for exposure and transfer operations of a step-and-repeat type and a step-and-scan type in which a photosensitive substrate such as a wafer or a glass substrate coated with a photosensitive material is exposed to a fine electronic circuit pattern formed on a surface of a mask using X-ray such as synchrotron radiation (SR) or plasma X-ray radiation source.
A X-ray exposure method and X-ray exposure device for manufacturing devices using X-ray generated by synchrotron radiation or plasma X-ray source or another X-ray source have been proposed.
Generally, the X-ray exposure device requires a light blocking plate, disposed in the optical path, for blocking X-ray to limit an exposure view angle (exposure area). This is different from a light exposure device using i-line, or an excimer laser beam or the like wherein the exposure area and the non-exposure area can be clearly separated by a light blocking film provided on the mask. On the contrary, in the X-ray exposure device, a light blocking film of X-ray absorbing material provided on the mask cannot completely block the X-ray, and several to 40% approx is passed, that is, it at most reduced the radiation, and in the X-ray is projected widely covering the light blocking film around the exposure view angle, the X-ray absorbing material constituting the light blocking film absorbs the X-ray with the result of rising of the mask temperature and therefore deviation of the pattern of the mask in the exposure view angle. This is the reason for the requirement of the light blocking plate in the optical path for the radiation.
When the light blocking plate for blocking the X-ray is disposed in the optical path (radiation path) of the X-ray exposure device in other to limit the exposure view angle (exposure area), the following problems arise.
In order to accomplish the limiting of the exposure view angle, the function of changing the exposure view angle in accordance with the area to be transferred (exposure area) of the mask. In order to limit the area to be transferred of the mask, the light blocking plates have to be provided which are movable in four directions, respectively, with high precision without mechanical interference with the mask and mask supporting members.
For this reason, the light blocking plates have to be disposed quite away from the mask. In this case, the positional relation among the size of the radiation source, the light blocking plate and the mask, a boundary region called penumbra due to the light blocking plate in which the amount of the projection X-ray gradually decreases, is generated on the mask.
Even if the light source is a very small, and the radiation source is distant from the mask, the width of the boundary region, that is, the penumbra is not negligible because of the influence of the diffraction if the surface to be exposed (wafer surface) and light blocking plate are away from each other by a substantial distance. As a result, there exist areas which cannot be used for the exposure, on the mask, and additionally, a small amount of the projection X-ray enters the adjacent exposure area.
Particularly in the case of the X-ray exposure device using the synchrotron radiation as the radiation source, the apparent shape of the radiation source is elliptical, and therefore, a marginal portion of the penumbra provided by the light blocking plate for limiting the exposure view angle may enter the adjacent exposure area.
It would be a solution to provide a boundary region having a sufficient area without any transfer pattern at all, around the transfer region (exposure area). However, this solution results in wasteful area enlarged, and therefore, the efficiency of the devices is low.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to provide an exposure method and an exposure device in which the width of the boundary region can be reduced so that devices can be manufactured with high efficiency and stability.
According to an aspect of the present invention, there is provided an exposure method using X-ray as exposure radiation, comprising a step of preparing a light blocking plate, disposed in an optical path, for blocking the exposure radiation; a step of limiting an exposure view angle on the mask by a light blocking plate such that area of penumbra provided on the mask by the light blocking plate cover an inner edge portion of a low intensity region formed on the mask; and a step of exposure and transfer of a pattern within the exposure view angle on the mask onto a photosensitive substrate.
According to another aspect of the present invention, there is provided an exposure method using X-ray as exposure radiation, comprising: a step of preparing a light blocking plate, disposed in an optical path, for blocking the exposure radiation; a step of limiting an exposure view angle on a mask by a light blocking plate in accordance with selection of exposure of an area outside an exposure area to be projected and transferred onto a photosensitive substrate; a step of exposure and transfer of a pattern within the exposure view angle on the mask onto a photosensitive substrate.
According to a further aspect of the present invention, there is provided an exposure apparatus, using X-ray as exposure radiation, for exposing a photosensitive substrate to a pattern within an exposure view angle on a mask to transfer the pattern onto the photosensitive substrate, said apparatus comprising a light blocking plate, disposed in an optical path for the exposure radiation, for limiting the exposure view angle on the mask by blocking the exposure radiation; driving means for driving said light blocking plate such that area of penumbra provided on the mask by the light blocking plate cover an inner edge portion of a low intensity region formed on the mask.
According to a further aspect of the present invention, there is provided an exposure apparatus, using X-ray as exposure radiation, for exposing a photosensitive substrate to a pattern within an exposure view angle on a mask to transfer the pattern onto the photosensitive substrate, said apparatus comprising a light blocking plate, disposed in an optical path for the exposure radiation, for limiting the exposure view angle on the mask by blocking the exposure radiation; driving means for driving said light blocking plate in accordance with selection of exposure of an area outside an exposure area to be projected and transferred onto a photosensitive substrate.
According to a further aspect of the present invention, there is provided a semiconductor device manufacturing method comprising a step of relative position alignment between a mask and a photosensitive substrate; a step of exposure and transfer of a pattern within the exposure view angle on the mask onto a photosensitive substrate, using X-ray as exposure radiation; said exposure step including: a step of preparing a light blocking plate, disposed in an optical path, for blocking the exposure radiation; a step of limiting an exposure view angle on the mask by a light blocking plate such that area of penumbra provided on the mask by the light blocking plate cover an inner edge portion of a low intensity region formed on the mask; and said manufacturing method further including: a step of developing the photosensitive substrate onto which the pattern has been transferred.
According to a further aspect of the present invention, there is provided a semiconductor device manufacturing method comprising: a step of relative position alignment between a mask and a photosensitive substrate; a step of exposure and transfer of a pattern within the exposure view angle on the mask onto a photosensitive substrate, using X-ray as exposure radiation; said exposure step including: a step of preparing a light blocking plate, disposed in an optical path, for blocking the exposure radiation; a step of limiting an exposure view angle on a mask by a light bl
Kasumi Kazuyuki
Miyachi Takeshi
Terashima Shigeru
Watanabe Yutaka
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