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US 6,587,201 B2Granted
Aligning apparatus and method for aligning mask patterns with regions on a substrate
AssigneeNikon Corporation
InventorKenji Nishi
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AssigneeNikon Corporation
InventorKenji Nishi
Estimating the term…
The present invention provides an alignment apparatus and method for successively bringing a plurality of shot regions to be processed on a substrate into alignment with a predetermined reference position. The invention performs a pre-alignment of the substrate and then repeatedly measures the position of wafer marks on selected preparatory sample shot regions using various coordinate systems. The invention determines the both the linear and rotational error in the position of the wafer marks relative to a predetermined reference position and determines the amount of movement of the substrate and reticle necessary to compensate for the error.
A position detecting method that obtains positional information of a plurality of regions formed on a substrate, comprising the steps of:
A position detecting method that obtains positional information of a plurality of regions formed on a substrate, comprising the steps of:
An exposure method that obtains positional information of a plurality of regions formed on a substrate and exposes a predetermined pattern in the plurality of regions based on the positional information that was obtained, comprising the steps of:
An exposure method that obtains positional information of a plurality of regions formed on a substrate and exposes a predetermined pattern in the plurality of regions based on the positional information that was obtained, comprising the steps of:
Dependencies are inferred from the claim text.
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Measuring arrangements characterised by the use of optical techniques: for measuring angles or tapers; for testing the alignment of axes
Measuring length, thickness or similar linear dimensions
Term ended 29 Jul 2018 (estimated)
The disclosures of the following priority application(s) are herein incorporated by reference:
Japanese Patent Application Laid Open No. 09-210315 filed Aug. 5, 1997.
1. Field of Invention
The invention is described in detail with reference to the following figures wherein like reference numerals designate similar items, and wherein:
FIG. 1 is a schematic illustration of the construction of a projection exposure apparatus of a preferred embodiment of the present invention;
FIG. 2A is a plan view of arrays of shots on a wafer W to be exposed in accordance with a preferred embodiment of the present invention;
An embodiment of the alignment method in accordance with the present invention will be described with reference to FIGS. 1 to 8.
FIG. 1 shows a projection exposure apparatus according to a preferred embodiment of the present invention. The projection exposure apparatus has an illumination optical system 8 which includes an exposure light source such as a mercury lamp or an excimer laser, a fly-eye lens for developing a uniform distribution of illuminance of the exposure light from the light source, an aperture, termed as a “reticle blind”, for defining the area to be illuminated, a condenser lens, and so forth as is known in the art. A reticle R is illuminated with exposure light IL at a uniform illuminance distribution. The image of a pattern formed on the reticle R is projected on each shot region on the wafer W, through a both-end telecentric projection optical system PL at a projection magnification β which is, for example. ⅕, ¼ or the like. The wafer W is coated with a photo-resist. A measuring system incorporated in the illumination optical system 8 indirectly monitors the dosage or rate of exposure on the photo-resist. A main control system 5 includes a computer which performs an overall control of the apparatus including the control of the exposure rate. Thus, the main control system 5 controls an exposure rate control system 11 which in turn controls the exposure light source so as to optimize the rate of exposure of the photo-resist.
The following description proceeds on an assumed three-dimensional space defined by a Z-axis parallel to the optical axis AX of the projection optical system PL, an X-axis which extends in a plane perpendicular to the Z-axis and which is parallel to the plane of the sheet containing FIG. 1, and a Y-axis which is orthogonal both to the X- and Z-axes. The reticle R is held by suction on a reticle stage 7 which is pneumatically supported in a floating manner on a reticle base 6 through a pneumatic bearing. The reticle stage 7 is adapted to be located in the X, Y and θ directions by actuating mechanisms such as linear motors (not shown). The reticle stage 7 has side surfaces including an X-axis mirror surface 7x and a Y-axis mirror surface. A laser interferometer 9 applies a three-axes laser beam onto these mirror surfaces of the reticle stage 7, so as to measure the X coordinate, Y coordinate and rotational angle of the reticle stage 7. The results of the measurement are delivered to a reticle stage driving system 10 and also to the main control system 5. The reticle stage driving system 10 controls the operation of the reticle stage 7 based on the measurement results and control information given by the main control system 5.