JPH1083950A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to improve throughput and exposing accuracy, by correcting the position deviation of an original plate with respect to an original-plate stage, by lifting the original plate from the upper part of the original-plate stage by a lifting and micromotion means, by minutely moving the plate in correspondence with the position deviation and by returning the plate to the upper part of the original-plate stage. SOLUTION: A reticle 34 is mounted on a reticle stage 32 by a reticle changer 32. Then, a reticle handler 36 is lifted, and the reticle 34 is lifted by the degree so that the reticle 34 is not deviated from the depth of the focus of a reticle alignment scope 33 from the reticle stage 1 by a push-up pin 36a. Under this state, the position deviation is detected by the reticle alignment scope 33. The position of the reticle 34 on the push-up pin 36a is determined based on the detected value. Furthermore, the reticle handler 36 is lowered, and the reticle 34 is returned to the reticle stage 1. Then, the amount of the position deviation is measured again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus used for manufacturing semiconductor devices such as ICs and LSIs, liquid crystal devices, imaging devices such as CCDs, and devices such as magnetic heads. The present invention relates to an exposure apparatus that reduces the weight of a stage and thereby improves throughput.

[0002]

2. Description of the Related Art In a batch exposure type exposure apparatus (stepper), when a projection optical system is constituted by a lens,
The imaging region has a circular shape. However, since the semiconductor integrated circuit generally has a rectangular shape, the transfer area in the case of batch exposure is a rectangular area inscribed in a circular imaging area of the projection optical system. Therefore, even the largest transfer area is a square of 1 / √2 of the diameter of the circle. On the contrary,
A scanning exposure method in which a transfer area is enlarged by moving a reticle and a wafer synchronously using a slit-shaped exposure area having a diameter substantially equal to the diameter of a circular imaging area of the projection optical system ( Step-and-scan method) has been proposed. In this method, when a projection optical system having an imaging area of the same size is used, a larger transfer area is secured as compared with the step-and-repeat method in which collective exposure is performed for each transfer area using a projection lens. be able to. That is, since there is no restriction by the optical system in the scanning direction, it is possible to secure only the stroke of the scanning stage, and it is possible to secure approximately √2 times the transfer area in the direction perpendicular to the scanning direction. .

An exposure apparatus for manufacturing a semiconductor integrated circuit is required to have an enlarged transfer area and an improved resolution in order to cope with the manufacture of a chip having a high degree of integration. The fact that a smaller projection optical system can be employed is advantageous from the viewpoint of optical performance and cost, and the exposure method of the step-and-scan method is attracting attention as a mainstream of future exposure apparatuses.

In such a step-and-scan type exposure apparatus, it is necessary to align a reticle and a wafer with high accuracy. For example, a reticle placed on a reticle stage by reticle exchange or the like is controlled by a reticle alignment scope. The position of the reticle stage with respect to the reference mark is measured with high accuracy. In this reticle scope, the higher the accuracy, the narrower the measurement range,
The measurement range of the reticle alignment scope in the 256M-compatible exposure apparatus aimed at by the present inventors is 2 μm
It is about.

In a conventional reticle hand, a reticle is
It is firstly impossible to mount on a reticle stage with an error of about μm. Therefore, XYθ is placed on the reticle stage.
It is conceivable to provide a fine movement mechanism and switch the reticle alignment scope to a low magnification to drive the reticle displacement to within 2 μm. However, when the XYθ fine movement mechanism is provided on the reticle stage, the reticle stage becomes heavy, and in particular, in a scanning type exposure apparatus that scans the reticle, the moving speed of the stage becomes slow and the throughput decreases. Problems such as a decrease in exposure accuracy due to bending of the surface plate occur.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to reduce the weight of an original stage in an exposure apparatus and improve throughput and exposure accuracy. And

[0007]

In order to achieve the above object, according to the present invention, a part of an original pattern is projected onto a substrate via a projection optical system, and the original is relatively moved with respect to the projection optical system. And an exposure apparatus for exposing the pattern of the original onto the substrate by scanning the substrate together with an original stage for holding the original and exchanging the original on the original stage at a predetermined original exchange position outside the exposure area. Exchange means;
Means for detecting a displacement of the original on the original stage relative to the original stage at the original exchange position, means for elevating the original relative to the original stage at the original exchange position, and an original lifted by the elevating means Means for finely moving the original in a pattern drawing plane of the original and about an axis perpendicular to the plane, and lifting and lowering the original from the original stage by these elevating and fine moving means, and finely moving according to the positional shift, and Control means for correcting a positional shift of the original with respect to the original stage by returning the original to the original stage.

In a preferred embodiment of the present invention, the fine movement means comprises a fine movement stage movable in a pattern drawing plane of the original and about an axis perpendicular to the plane. A vertical through-hole is provided at a predetermined location, and the elevating means includes a plurality of push-up pins passing through the through-hole, and includes an original handler fixed on the fine movement stage and moving up and down the push-up pins. It is characterized by the following. Further, a vacuum suction means for suction-holding the original is provided at the tip of the push-up pin, and the push-up pins support four corners of the original and lift the original.

[0009]

According to the present invention, the fine movement mechanism for aligning the original is not mounted on the original stage, that is, the original stage is reduced in weight, so that the throughput (scan speed) and the exposure accuracy are improved. Can be achieved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a state of an exposure apparatus according to an embodiment of the present invention as viewed from the side, and FIG. 2 is a perspective view showing an appearance of the exposure apparatus. As shown in these drawings, this exposure apparatus uses a projection optical system 2 to project a part of an original pattern on a reticle stage 1 through a wafer stage 3.
The reticle and the wafer are synchronously scanned in the Y direction relative to the projection optical system 2 to expose the reticle pattern to the wafer, and this scanning exposure is performed on a plurality of transfer areas on the wafer. (Shot) is a step-and-scan type exposure apparatus which performs step movement for repeated execution.

The reticle stage 1 is driven by a linear motor 4 in the Y direction,
a is driven in the X direction by the linear motor 5, and the Y stage 3 b is driven in the Y direction by the linear motor 6. The synchronous scanning of the reticle and the wafer is performed by driving the reticle stage 1 and the Y stage 3b at a constant speed ratio in the Y direction (for example, 4: -1, where "-" indicates that the directions are opposite). Do. The step movement in the X direction is performed by the X stage 3a. A Z-tilt stage (not shown) is mounted on the X stage 3a, and a wafer chuck (not shown) for holding a wafer is mounted thereon.

The wafer stage 3 is provided on a stage base 7, and the stage base 7 is connected via three dampers 8.
It is supported on a floor at a point. The reticle stage 1 and the projection optical system 2 are provided on a barrel base 9, and the barrel base 9 is supported on a base frame 10 mounted on a floor or the like via three dampers 11 and columns 12. I have. The damper 8 is an active damper for actively damping or removing vibrations in six axial directions. However, a passive damper may be used, or the damper 8 may be supported without a damper.

The exposure apparatus further includes a distance measuring means 13 such as a laser interferometer or a micro encoder for measuring the distance between the lens barrel base 9 and the stage base 7 at three points.

The light projecting means 21 and the light receiving means 22 constitute a focus sensor for detecting whether or not the wafer on the wafer stage 3 is located on the focus surface of the projection optical system 2. That is, the wafer is irradiated with light from an oblique direction by the light projecting means 21 fixed to the lens barrel base 9, and the position of the reflected light is detected by the light receiving means 22, whereby the direction of the optical axis of the projection optical system 2 is adjusted. Of the wafer surface is detected.

In the apparatus shown in FIG. 1, light emitted from a laser interferometer light source (not shown) is introduced into a reticle stage Y-direction laser interferometer 24. The light introduced into the Y-direction laser interferometer 24 is transmitted to the laser interferometer 24 by a beam splitter (not shown) in the laser interferometer 24.
The light is divided into light directed toward a fixed mirror (not shown) and light directed toward the Y-direction movable mirror 26. The light traveling to the Y-direction moving mirror 26 passes through the Y-direction length measuring optical path 25 and enters the Y-direction moving mirror 26 fixed to the reticle stage 4. The light reflected here returns to the beam splitter in the laser interferometer 24 through the Y-direction length measuring optical path 25 again, and is superimposed on the light reflected by the fixed mirror. The movement distance in the Y direction is measured by detecting a change in light interference at this time. The movement distance information measured in this way is fed back to a scanning controller (not shown), and positioning control of the scanning position of the reticle stage 4 is performed. Similarly, the Y stage 3b controls the scanning position based on the length measurement result by the wafer stage Y direction laser interferometer 23.

In this configuration, when the wafer is loaded onto the wafer stage 3 via the transport path between the two columns 12 at the front of the apparatus by the transport means (not shown) and the predetermined alignment is completed, the exposure apparatus While repeating the scanning exposure and the step movement, the reticle pattern is exposed and transferred to a plurality of exposure regions on the wafer. At the time of scanning exposure, the reticle stage 1 and the Y stage 3b are moved at a predetermined speed ratio in the Y direction (scanning direction) to scan a pattern on the reticle with slit-like exposure light, and to project a wafer with the projected image. To expose a pattern on the reticle to a predetermined exposure area on the wafer. During the scanning exposure, the height of the wafer surface is measured by the focus sensor, and the height and tilt of the wafer stage 3 are controlled in real time based on the measured values, and focus correction is performed. When the scanning exposure for one exposure region is completed, the X stage 3a is driven in the X direction to move the wafer stepwise, thereby positioning the other exposure region with respect to the start position of the scanning exposure and performing the scanning exposure. The combination of the step movement in the X direction and the movement for scanning exposure in the Y direction allows each of the exposure areas to be sequentially and efficiently exposed to a plurality of exposure areas on the wafer. , The scanning direction of either positive or negative Y, the order of exposure to each exposure area, and the like are set.

During reticle alignment, the reticle stage 1 moves to a reticle alignment position outside the exposure area and receives a reticle from a reticle changer (not shown). The reticle stage and a reticle stage guide for guiding the reticle are provided with through holes for passing a reticle handler (not shown). The reticle handler rises, grasps the reticle, drives a reticle alignment stage (not shown), and aligns the reticle with respect to a reference mark on the reticle stage 1. At the time of alignment, vacuum is sucked at the tip of the reticle handler to prevent misalignment.

FIG. 3 shows the configuration of the reticle alignment mechanism in the apparatus shown in FIG. In this apparatus, the reticle alignment mechanism is not mounted on the reticle scan stage, but is separately provided, thereby reducing the weight of the reticle stage, increasing the scanning speed, and improving the throughput. Reticle alignment is performed at the reticle exchange position. In the figure, reference numeral 1 denotes a reticle stage, a solid line indicates a state at a reticle alignment position (that is, a reticle replacement position), and a two-dot chain line indicates a state at a exposure area. Reference numeral 2 denotes a projection optical system (projection lens), 3 denotes a wafer stage, 31 denotes an illumination optical system, 32 denotes a reticle changer, 33 denotes a substrate position detection microscope (reticle alignment scope), 34 denotes a reticle, and 35 denotes a reticle stage. Reference mark, 36 is a reticle handler, 36a is a push-up pin forming a part of the reticle handler 36, 37 is a reticle alignment stage, 38 is a reticle stage guide, and 1a and 38a are push-up pins 36a passing when the reticle handler 36 is raised. A through hole provided so as to be able to be provided, 39 is a wafer stage guide, and 40 is a wafer.

FIG. 4 shows the operation of each unit when the reticle is replaced. That is, at the time of reticle replacement, a new reticle 34 is transferred from a reticle library or the like (not shown) by a transfer means (not shown) and delivered to the reticle changer 32.
The reticle is placed on the reticle stage 1 by the reticle changer 32 (FIG. 4A). Next, reticle handler 3
The reticle 34 is lifted up from the reticle stage 1 by the push-up pins 36a, so that the reticle 34 does not deviate from the depth of focus (for example, 10 μm) of the reticle alignment scope 33, for example, about 2 to several μm. In this state, the reticle alignment scope 33 detects a positional shift between the reference mark 35 and an alignment mark (not shown) formed on the reticle 34, and drives the reticle alignment stage 37 based on the detected value to drive the reticle 34. The reticle 34 on the push-up pin 36a is positioned so that the position alignment mark is located at the measurement center of the alignment scope 33 (FIG. 4B). further,
The reticle handler 36 is lowered to return the reticle 34 to the reticle stage 1 (FIG. 4C), and the reticle alignment scope 33 measures the amount of displacement between the alignment mark on the reticle 34 and the reference mark 35 of the reticle stage 1 again. The wafer stage 3 according to the measured value.
Scan exposure is performed by setting XYθ of the upper wafer.

When detecting the above-mentioned positional deviation, first, before moving up the reticle handler 36, the reticle 3
4 is observed with a reticle alignment scope 33, and if the alignment mark of the reticle 34 is within the measurement range of the reticle alignment scope 33, the above-described position shift amount measurement and scanning exposure are performed without performing the above-described positioning processing. You can also do it. In this case, when the alignment mark of the reticle 34 is not within the measurement range of the reticle alignment scope 33 but is within the field of view of the reticle alignment scope 33, the reticle 34 is not changed without changing the magnification of the reticle alignment scope 33. Is detected, and if the alignment mark of the reticle 34 is not within the field of view of the reticle alignment scope 33, the magnification of the reticle alignment scope 33 is switched to a low magnification, and the alignment mark is Is detected. This magnification switching is performed in parallel with the elevation of the reticle handler 36. When the magnification is changed, the magnification is restored in parallel with the lowering of the reticle handler 36.

In the apparatus shown in FIG. 1, the above-mentioned reticle alignment can be appropriately performed other than when the reticle is replaced. FIG. 5 shows details of the reticle alignment. Regarding the reticle alignment, regardless of the reticle exchange, first, the reticle stage 1 is moved to the reticle alignment position (that is, the reticle exchange position) (FIG. 5).
(A)) Perform. At the reticle alignment position, the reticle handler 36 is raised to such an extent that the reticle 34 of the reticle stage 1 is slightly lifted from the reticle stage 1 (FIG. 5B). Reticle handler 3
As shown in FIG. 5C, an adsorbing portion 51 capable of adsorbing the reticle 34 in vacuum is provided at the tip of the push-up pin 36a. The reticle stage is also mounted on the reticle stage.
Reticle chuck 52 for vacuum-sucking is provided. When the reticle 34 is lifted, the reticle 34 is lifted up by the suction portion 51 and vacuum-adsorbed to the tip of the pin 36a.
The displacement of the reticle 34 from the push-up pin 36a is prevented. At this time, the vacuum suction of the reticle chuck 52 can be turned on / off.

When the reticle 34 is slightly lifted from the reticle stage 1, the reticle alignment scope 33 detects the positional deviation between the reference mark 35 and the alignment mark on the reticle 34 as described above. Reticle alignment stage 37 is driven to correct (reticle alignment). further,
The reticle handler 36 is lowered, and if the vacuum suction of the reticle chuck 52 is turned off, it is turned on, the vacuum suction of the reticle push-up pin 36a is turned off, and the aligned reticle 34 is delivered to the reticle stage 1.

When the reticle alignment is completed, the alignment marks on the reticle 34 and the reticle stage 1 are moved by the reticle alignment scope 33 as described above.
XYθ of the wafer on the wafer stage 3 is set based on the measured value and the residual alignment error of the wafer, and scanning exposure is performed.

FIG. 6 shows a flow chart for manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin film magnetic heads, micro machines, etc.). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 7 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been conventionally difficult to manufacture, at low cost.

[0027]

As described above, according to the present invention, the original plate alignment mechanism is not mounted on the original plate stage, but is separately provided. Therefore, the original plate stage is reduced in weight, the scanning speed of the original plate stage is increased, and the throughput is improved. Can be improved. In addition, the deflection of the stage base and the like due to the weight of the original stage can be reduced, and the exposure accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a state of an exposure apparatus according to one embodiment of the present invention when viewed from a side.

FIG. 2 is a perspective view showing an appearance of the exposure apparatus of FIG.

FIG. 3 is an explanatory diagram of a reticle alignment mechanism in the apparatus of FIG.

FIG. 4 is a diagram illustrating the operation of the reticle alignment mechanism.

FIG. 5 is an explanatory diagram of a reticle alignment process.

FIG. 6 is a diagram showing a flow of manufacturing a micro device.

FIG. 7 is a diagram showing a detailed flow of a wafer process in FIG. 6;

[Explanation of symbols]

1: reticle stage, 1a: through hole, 2: projection optical system, 3: wafer stage, 3a: X stage, 3b: Y
Stage, 4, 5, 6: linear motor, 7: stage base, 8: damper, 9: lens barrel base, 10: base frame, 11: damper, 12: support, 13: distance measuring means,
21: light emitting means, 22: light receiving means, 23, 24: laser interferometer, 25: laser measuring optical path, 26, 27: moving mirror,
31: illumination optical system, 32: reticle changer, 33:
Reticle alignment scope, 34: reticle, 3
5: reference mark, 36: reticle handler, 36a: reticle push-up pin, 37: reticle alignment stage, 38: reticle stage guide, 38a: through hole, 39: wafer stage guide, 40: wafer, 5
1: suction part, 52: reticle chuck.

Claims (5)

[Claims] 1. A pattern of an original is projected onto a substrate by projecting a part of the pattern of the original onto a substrate via a projection optical system and scanning the original and the substrate together with respect to the projection optical system. In an exposure apparatus for exposing, an original stage for holding an original, original exchange means for exchanging an original on the original stage at a predetermined original exchange position outside an exposure area, and a position of the original on the original stage with respect to the original stage. Means for detecting a displacement at the original exchange position, means for elevating the original relative to the original stage at the original exchange position, and applying the original lifted by the elevating means to a plane within the pattern drawing plane of the original and to the plane. Means for finely moving around the vertical axis, and lifting and lowering of the original from the original stage by these elevating and fine moving means, and finely moving according to the displacement,
An exposure apparatus comprising: control means for correcting a positional shift of the original with respect to the original stage by returning the original to the original stage. 2. The fine movement means comprises a fine movement stage which is movable in a pattern drawing plane of the original and about an axis perpendicular to the plane, and a predetermined position of the original stage and its supporting and driving system is provided in a vertical direction. A through-hole is provided, and said elevating means comprises a master handler having a plurality of push-up pins passing through said through-hole and fixed on said fine movement stage to raise and lower said push-up pins. 2. The exposure apparatus according to 1. 3. An exposure apparatus according to claim 2, wherein a vacuum suction means for sucking and holding said master is provided at a tip of said push-up pin. 4. The exposure apparatus according to claim 1, wherein said lifting means lifts and lowers the original while supporting four corners of the original. 5. A semiconductor device manufactured by using the mold exposure apparatus according to claim 1. Description: