JP2015081995A - Exposure apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exposure apparatus which reduces the measurement time for positioning while minimizing deterioration of the accuracy of positioning of a circuit pattern already transferred to a glass plate and a circuit pattern of a photomask.SOLUTION: In positioning a circuit pattern of a photomask serving as an original plate and a glass plate which is mounted on a plate stage and already transferred with a circuit pattern, an alignment mark on a photomask and an alignment mark on the glass plate are measured simultaneously at a typical position on the glass plate to determine positions to individual alignment scopes. At other positions, only a relative position between the alignment mark and the alignment scope is measured, and a relative position between the alignment mark on the glass plate and the alignment mark on the photomask at other positions is calculated from the results of the measurement of the relative position and results of a relative position of the alignment mark on the photomask relative to the alignment scope measured at a typical position of the glass plate.

Description

  The present invention relates to an exposure apparatus that exposes a substrate (a wafer, a glass plate, or the like) pattern of an original plate (such as a photomask or a reticle) such as a mask in a manufacturing process of a semiconductor integrated circuit, a liquid crystal display element, or the like.

  In a conventional exposure apparatus, when the second circuit pattern is aligned with the first circuit pattern and exposed to the glass plate to which the first circuit pattern is transferred, the second circuit is formed on the photomask. Measures the amount of misalignment between the alignment mark drawn around the pattern and the alignment mark drawn around the first circuit pattern on the glass plate, and aligns the photomask with the glass plate. (See Patent Document 1). In the positional deviation amount measurement, both marks are simultaneously observed in the same field of view with an alignment scope, and the relative position of the glass plate side mark with respect to the photomask side mark is measured by an image processing apparatus. This is called pinching measurement.

  Also, in order to expose as many circuit patterns drawn on a photomask as possible on a single glass plate, the same circuit pattern is exposed as a single shot, and multiple shots are exposed on a single glass plate. doing.

JP 2003-203848 A

  A problem to be solved by the present invention will be described with reference to FIG.

  When measurement is performed with a photomask and a glass plate mark sandwiched between shots, it is necessary to perform alignment measurement by making the transferred mask pattern coincide with the direction of each shot on the glass plate. Therefore, with the alignment scope position fixed, the mask stage and plate stage are synchronized in the longitudinal (Y) direction and driven in the same direction in the shot. When stepping in the lateral (X) direction as in shot 1 → shot 2, only the plate stage is driven in the X direction. When a shot needs to be exposed over two rows, only the plate stage is driven in the Y direction when stepping in the Y direction as in shot 3 → shot 4. At this time, when the alignment measurement of shot 3 is completed, the mask stage has already been driven in the back direction (upward in FIG. 1 (1-1)). The plate stage needs to be step-driven further in the back and back direction (upward direction in FIG. 1 (1-1)) over a distance equal to or greater than the Y range of one shot. The throughput will decrease.

  Therefore, an object of the present invention is to improve the throughput when the first layer shot is exposed over two rows.

  In order to achieve the object, means for storing the mark position on the photomask side in the alignment of shot 1 is provided in the exposure apparatus.

  For the next shot and thereafter, only the glass plate side mark position is measured, the relative position from the already stored photomask side mark is obtained by calculation, alignment is performed, and exposure is performed. Thus, after the second shot, the plate stage can be driven and the throughput can be optimized without depending on the position of the mask stage.

  Referring to the example shown in FIG. 1 (1-2), in shot 1, the mask stage and the plate stage are driven synchronously to perform alignment measurement. From the next shot onwards, only the plate stage is shot 6 → shot 5 → shot 2 → shot 3 → Drive in order of shot 4 to perform alignment measurement. As a result, the driving distance can be greatly reduced, and the throughput can be improved.

As shown in FIG. 1 (1-1), the Y-direction distance between alignment marks adjacent in the Y direction in a shot is a, the X-direction distance between shot centers is b in adjacent shots, and the Y spans adjacent shots. When the Y-direction distance between marks close to the direction is c, when shot 1 to shot 6 are aligned by the conventional alignment method,
The total driving distance d is
d = 15a + 4b + c
It becomes.

On the other hand, when shot 1 to shot 6 are aligned by the alignment method of the present invention,
The total driving distance e is
e = 13a + 2b + 4c
It becomes.

Therefore, the driving distance is
d−e = 2a + 2b−3c
As a result, the tact time is shortened, and as a result, the throughput can be improved.

It is a figure explaining the subject which this invention solves. It is a figure explaining the System configuration of the present invention. It is a figure explaining the concept of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First embodiment]
The system configuration of the present invention will be described with reference to FIG.

  A glass plate 2 is placed on the plate stage 1. A photomask 4 is placed on the mask stage 3.

  On the glass plate 2, the circuit pattern of the first layer is exposed from shot 1 (5) to shot 6 (10), and alignment marks are exposed at 6 points (11 to 16) of shot 1 (5). Yes. Here, (11) and (12) are called P1 (S1), (13) and (14) are called P2 (S1), and (15) and (16) are called P3 (S1). In addition, six alignment marks (47 to 52) are also drawn on the photomask 3. (47) and (48) are called P1 (M), (49) and (50) are called P2 (M), and (51) and (52) are called P3 (M). When performing alignment measurement, the position of the alignment scope 53 is fixed, the mask stage 3 and the plate stage 1 are driven synchronously, and the relative position of the P2 (S1) and P2 (M) relative to the alignment scope (53) is measured simultaneously. To do.

  Next, the mask stage 3 and the plate stage 1 are driven synchronously to simultaneously measure the relative positions of P1 (S1) and P1 (M) with respect to the alignment scope. Further, the mask stage 3 and the plate stage 1 are driven synchronously to simultaneously measure the relative positions of P3 (S1) and P3 (M) with respect to the alignment scope 53. Using the relative position of P1 (S1) with respect to P1 (M), the relative position of P2 (S1) with respect to P2 (M), and the relative position of P3 (S1) with respect to P3 (M), obtained from each measurement result The amount of positional deviation between the circuit pattern of the photomask and the circuit pattern of shot 1 (5) is known, and it is possible to perform transfer exposure by aligning based on these values.

  At this time, the value of the relative position of the photomask side alignment mark of P1 (M), P2 (M), and P3 (M) with respect to the alignment scope 53 is stored in the storage device.

  Next, only the plate stage (1) is driven in the longitudinal (Y) direction, and the relative position of the shot P1 (S6) of the shot 6 (10) to the alignment scope (53) is measured. Since the position of the P1 (M) photomask side alignment mark is stored during the shot 1 alignment measurement, the relative position of P1 (M) and P1 (S6) can be calculated via the alignment scope position. Similarly, by driving only the plate stage (1) and measuring the relative position of each shot alignment mark with respect to the alignment scope (53), the relative position of the photomask side alignment mark and the glass plate side alignment mark of the shot 6 can be determined. It can be calculated.

  Similarly, in the order of shot 5 → shot 2 → shot 3 → shot 4, calculate the relative displacement amount of the circuit pattern on the photomask and the circuit pattern on the glass plate, and perform transfer exposure while performing alignment. .

[Second Embodiment]
The method of minimizing the degradation of alignment accuracy according to the present invention will be described with reference to FIGS.

  In the first embodiment, it is assumed that the relative position between the alignment mark of the photomask 4 and the alignment scope 53 does not change when the mask stage 3 and the alignment scope 53 are stopped. However, when the alignment scope 53 is movable, it is difficult to physically stop the alignment scope, and in many cases, the alignment scope 53 actually vibrates slightly. When higher alignment accuracy is required, an error due to the vibration of the alignment scope 53 may not be allowed.

  Therefore, when P2 (S1) of shot 1 (5) and P2 (M) on the photomask 4 are first measured by the alignment scope 53, the mask stage 3 and the plate stage 1 are synchronously controlled, and P2 (S1) And maintain the positional relationship between P2 (M). Next, only the mask stage 3 is step driven, and the mask stage 3 and the plate stage 1 are synchronously controlled to measure P2 (S1) and P1 (M). Similarly, P2 (S1) and P3 (M) are also measured. From the above results, the positional relationship of P1 (M), P2 (M), P3 (M) with respect to P2 (S1) is obtained, and further, the positional relationship of P1 (M) / P2 (M) / P3 (M) is also obtained. (Details: Fig. 4 (4-1)).

  After that, as in the first embodiment, only the plate stage 1 is driven to measure each alignment mark of each shot. However, in the measurement, the mask stage 3 and the plate stage 1 are synchronously controlled to obtain P3 (M). Find the positional relationship.

  For example, in the case of measurement of shot 6 (10), if the relative positions of P3 (M) and P1 (S6) are measured, the positional relationship between P1 (M) and P3 (M) is obtained, so P1 (M) And P1 (S6) can be calculated. Similarly, based on the relative position measurement results of P3 (M) and P2 (S6), the positional relationship between P2 (M) and P2 (S6) is calculated using the relative position of P2 (M) and P3 (M) obtained earlier. Thus, the exposure operation can be performed by aligning the circuit pattern of the shot 6 (10) with the circuit pattern of the photomask 4.

1 Plate stage 2 Glass plate 3 Mask stage 4 Photomask

Claims (2)

  When aligning the circuit pattern of the original photomask with the projection optical system and the glass plate mounted on the plate stage to which the circuit pattern has already been transferred, the photomask is placed at a representative position on the glass plate. The upper alignment mark and the alignment mark on the glass plate are measured at the same time to determine the position with respect to each alignment scope. At other positions, only the relative position between the alignment mark on the glass plate and the alignment scope is measured. And the relative position of the alignment mark on the photomask relative to the alignment scope measured at a representative position on the glass plate. Calculate Exposure apparatus characterized by.   When aligning the photomask circuit pattern and the circuit pattern on the glass plate, the relative positions of the alignment mark on the glass plate and each alignment mark on the photomask are measured. 2. An exposure apparatus according to claim 1, wherein a relative position between each alignment mark is calculated.