Photocopying – Projection printing and copying cameras – Step and repeat
Reexamination Certificate
1998-10-29
2001-07-17
Gray, David M. (Department: 2851)
Photocopying
Projection printing and copying cameras
Step and repeat
C356S401000
Reexamination Certificate
active
06262796
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a positioning device having a guiding surface extending parallel to an X-direction and parallel to a Y-direction, a first object holder and a second object holder which are each guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position, and a displacement system for displacing the first object holder and the second object holder over the guiding surface.
The invention further relates to a lithographic device provided with a radiation source, a mask holder, a focusing unit having a main axis, a characterization unit, and a positioning device, said positioning device comprising a guiding surface extending parallel to an X-direction, which is perpendicular to the main axis, and parallel to a Y-direction, which is perpendicular to the X-direction and the main axis, a first substrate holder and a second substrate holder which are each guided over the guiding surface and are each displaceable parallel to the X-direction and parallel to the Y-direction from a first position into a second position which is present near the focusing unit, and a displacement system for displacing the first substrate holder and the second substrate holder over the guiding surface.
A positioning device and a lithographic device of the kinds mentioned in the opening paragraphs are known from EP-A-0 687 957. The known lithographic device is used for the exposure of semiconductor substrates in the manufacturing process of integrated semiconductor circuits and operates according to the so-called step-and-repeat process. The known positioning device is used in the known lithographic device for displacing semiconductor substrates relative to the focusing unit and relative to the characterization unit. The first position of the known positioning device is a load and unload position in which a semiconductor substrate can be loaded on or unloaded from the first or the second object holder. The second position of the positioning device is an exposure position in which a semiconductor substrate present on the first or the second object holder can be exposed via the focusing unit. The first and the second object holder are displaceable from the first position to the second position and vice versa by the displacement system of the positioning device which is not described in detail in EP-A-0 687 957. When the first object holder is in the second position and the semiconductor substrate present thereon is being exposed, the second object holder is in the first position and a next semiconductor substrate is loaded thereon at first. Then the second object holder is displaced from the first position to a characterization position in which the semiconductor substrate present on the second object holder is characterized by the characterization unit. When the second object holder is in the characterization position, the first object holder and the second object holder are displaced lockstep-wise. In this manner the exposure of the semiconductor substrate present on the first object holder and the characterization of the semiconductor substrate present on the second object holder are carried out simultaneously, so that a high throughput of the step-and-repeat apparatus is obtained.
A disadvantage of the known positioning device and the known lithographic device is that the characterization of the semiconductor substrate present on the second object holder and the exposure of the semiconductor substrate present on the first object holder cannot be carried out independently from each other as a result of said lockstep-wise displacements of the first and the second object holder. As a result, the exposure of the semiconductor substrate present on the first object holder cannot be started until the second object holder has reached the characterization position.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a positioning device of the kind mentioned in the opening paragraph in which a first process involving a first series of positioning steps of the first object holder can be carried out simultaneously with and independently from a second process involving a second series of positioning steps of the second object holder, and in which also the first process can be carried out with the second object holder and, simultaneously and independently, the second process can be carried out with the first object holder.
It is a further object of the present invention to provide a lithographic device of the kind mentioned in the second paragraph in which a characterization process involving a first series of positioning steps of the first substrate holder can be carried out simultaneously with and independently from an exposure process involving a second series of positioning steps of the second substrate holder, and in which also the characterization process can be carried out with the second substrate holder and, simultaneously and independently, the exposure process can be carried out with the first substrate holder.
The positioning device according to the invention is for this purpose characterized in that the displacement system comprises a first displacement unit and a second displacement unit to which the first object holder and the second object holder can be coupled alternately, the first displacement unit being suitable for displacing the object holders from the first position into an intermediate position between the first position and the second position, and the second displacement unit being suitable for displacing the object holders from the intermediate position into the second position. As a result of the use of said first and second displacement units, a first process involving a first series of positioning steps of the first object holder can be carried out in the first position by means of the first displacement unit, and a second process involving a second series of positioning steps of the second object holder can be carried out in the second position by means of the second displacement unit simultaneously with and independently from the first process. When the first process and the second process have been completed, the first object holder is displaced by the first displacement unit from the first position into the intermediate position and the second object holder is displaced by the second displacement unit from the second position into the intermediate position. In the intermediate position, the first object holder is uncoupled from the first displacement unit and is coupled to the second displacement unit, while the second object holder is uncoupled from the second displacement unit and is coupled to the first displacement unit. Subsequently, the first object holder is displaced by the second displacement unit from the intermediate position to the second position and the second object holder is displaced by the first displacement unit from the intermediate position to the first position. Then the first process can be carried out with the second object holder in the first position and, simultaneously and independently, the second process can be carried out with the first object holder in the second position. Furthermore, as a result of the use of said two displacement units, a distance over which each individual displacement unit has to displace the object holders is reduced, so that the required dimensions of the displacement units are reduced. It is in addition prevented that the displaceable parts of the first displacement unit and the displaceable parts of the second displacement unit must be constructed so as to be capable of passing one another, which allows a comparatively simple construction of the displacement units.
The lithographic device according to the invention is for this purpose characterized in that the positioning device of the lithographic device is a positioning device according to the invention, wherein each of the object holders of the positioning device is a substrate holder of the lithographic device, an
Bonnema Gerrit M.
Kwan Yim-Bun P.
Loopstra Erik R.
Van Der Schoot Harmen K.
Veldhuis Gerjan P.
ASM Lithography B.V.
Gray David M.
Kim Peter B.
Pillsbury & Winthrop LLP
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