JP2000195785A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the vibration or deformation of a projection optical system or body system by equalizing the force generated by an original plate stage to the force generated by a substrate stage when the original plate stage and the substrate stage move synchronously. SOLUTION: A reticle 1 has a pattern focused and projected on a wafer 4 for forming a semiconductor device through reflection mirrors 12, 13 with synchronizing a reticle stage 2, and a wafer stage 5 in the slit direction X at the reduction magnification of a projection lens 3, and in the direction Y at the rate of the reduction magnification ratio of the lens 3. For the projection exposure, the reticle stage 2 and the wafer stage 5 are driven synchronously in the direction Y with the same sense as that of coordinate axes 9, 10 of the stages, the mass ratio of the reticle stage 2 to the wafer stage 5 is set so as to equalize the drive reactions of both stages, and both stages are disposed so that they act in the reverse directions on the same action line with a reaction receiver 8 disposed between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus, and more particularly to a method of manufacturing an element by synchronizing a stage on which a mask substrate for manufacturing an element is mounted with a stage on which a substrate such as a semiconductor wafer is mounted. And a projection exposure apparatus.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device,
An optical exposure apparatus that transfers a fine pattern of a reticle onto a wafer coated with a photosensitive agent has been used. The mainstream exposure method is a step-and-repeat method in which a wafer is sequentially moved into an exposure field of an exposure projection optical system to sequentially expose a reticle pattern.

Recently, there has been an increasing demand for a larger field of an exposure area in accordance with an increase in the size of a semiconductor device. As a method for meeting this requirement, a predetermined area of a reticle is irradiated with a slit or an arc-shaped illumination light so as to meet the demand. A step-and-scan method has been proposed in which exposure is performed in the longitudinal direction at the reduction magnification of the projection optical system, and exposure is performed in the short direction while synchronizing the reticle and the wafer with the reduction magnification ratio of the projection optical system.

The pattern on the reticle is sequentially exposed on the wafer by synchronizing the reticle stage and the wafer stage. At this time, the speed of the reticle stage and the speed of the wafer stage are moved so as to be equal to the projection magnification ratio.

FIG. 2 shows the configuration of a conventional step-and-scan projection exposure apparatus. In FIG.
In the pattern of the reticle 101, the X direction (longitudinal direction) of the slit is the reduction magnification of the projection lens 103, and the Y direction (short direction) is the reticle stage 102 and the wafer stage 105.
Are synchronized at the speed of the reduction ratio of the projection lens 103 (4: 1 in this example), so that an image is projected on the wafer 104 for producing a semiconductor device. The reticle stage base 106 and the wafer stage base 107 on which both stages are mounted are respectively reticle reaction force receiving parts 108,
It is connected to a structure 110 via a wafer reaction force receiver 109. The projection lens 103, the reticle stage base 106, and the wafer stage base 107 are composed of a main body structure 111.
Is configured.

In the case of the conventional example shown in FIG. 2, when performing projection exposure, the reticle stage 102 and the wafer stage 105 are driven synchronously in the same direction Y of the coordinate axes 112 and 113 of the respective stages. At that time, the driving reaction force of each stage is released from the main body by the reaction force receivers 108 and 109, respectively, but cannot be reduced to zero. Therefore, the residual reaction force is transmitted to the main body structure, causing vibration and deformation.
As a result, there is a problem that the accuracy of the projection lens and the measurement system is deteriorated, and the contrast, the resolving power, the alignment accuracy, and the like are reduced.

As described above, in the conventional exposure apparatus of this type, there is no correlation between the driving reaction force of the reticle stage and the driving reaction force of the wafer stage, and the arrangement is such that the driving reaction force of both stages is offset. Was not turned.

[0008]

A reaction force is generated when the reticle stage and the wafer stage are accelerated from a stopped state to a constant speed state and when the reticle stage and the wafer stage are decelerated from a constant speed state to a stationary state. However, as described above, in the prior art, since the mass and arrangement of both stages were not taken into account, a reaction force was applied to the projection optical system and the main body system supporting the same, causing vibration and deformation. As a result, there is a problem in that the synchronization accuracy of both stages is deteriorated, and the contrast, resolution, alignment accuracy, and the like are reduced.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and the product of the mass and acceleration of the reticle stage at the time of synchronous driving is equal to the product of the mass and acceleration of the wafer stage. In order to prevent vibration and deformation of the projection optical system and the main body system that supports it, by equalizing the drive reaction force generated in both stages and further devising the arrangement and mechanism, the contrast and resolution And to improve alignment accuracy.

That is, a projection exposure apparatus according to the present invention comprises: an illumination optical system for illuminating a predetermined illumination area of an original; a projection optical system for projecting an original pattern in the illumination area onto a substrate at a predetermined magnification; A projection exposure apparatus including an original stage movable in a predetermined direction with respect to an illumination area, and a substrate stage movable in a predetermined direction in synchronization with the original stage with respect to an exposure area conjugate to the illumination area. When the original stage and the substrate stage move synchronously, a force generated by the original stage and a force generated by the substrate stage are equal to each other.

Here, when the original stage and the substrate stage move synchronously, the force generated by the original stage and the force generated by the substrate stage are equal to each other. This is achieved by making the product of the original stage mass and the original stage acceleration equal to the product of the substrate stage mass and the substrate stage acceleration at each moment when moving in synchronization.

In one aspect, in the projection exposure apparatus of the present invention, both stages are arranged so that a force generated when the original stage and the substrate stage move synchronously is canceled. Arranging both stages so that the force generated when the original stage and the substrate stage move synchronously is, for example, such that the reaction force during the synchronous movement of both stages is canceled. The two stages may be arranged so that they are on the same line of action and the reaction force directions are opposite.

In addition, the projection exposure apparatus of the present invention includes a mechanism for canceling a reaction force generated when the original stage and the substrate stage move synchronously. As a mechanism for canceling the reaction force, there is a reaction force reception. The reaction force receiver has a buffer mechanism such as a spring, a hydraulic cylinder, or a linear motor. When the reaction force is applied, the buffer absorbs the reaction force and gradually releases the reaction force. It has.

In the present invention, the original on which the pattern is formed is a mask substrate or a reticle substrate, and the substrate on the stage is a photosensitive substrate or a semiconductor wafer substrate.

The present invention also includes a device manufacturing method characterized by manufacturing a device using the above-described projection exposure apparatus.

[0016]

In the present invention, since the driving reaction forces of the reticle stage and the wafer stage can be equalized and offset, vibration and deformation of the projection optical system and the main body system can be reduced.
Contrast, resolution and alignment accuracy can be improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to this embodiment. FIG. 1 shows steps to which an embodiment of the present invention is applied.
1 shows a configuration of an AND scan type projection exposure apparatus. In FIG. 1, a reticle 1 having a circuit pattern is illuminated by slit illumination light IL having a uniform illuminance. In the pattern of the reticle 1, the X direction (longitudinal direction) of the slit is the reduction magnification of the projection lens 3 and the Y direction (short direction) is the reduction ratio of the reticle stage 2 and the wafer stage 5 of the projection lens 3 (in this embodiment, 4: 1), the image is projected on the wafer 4 for semiconductor device production via the reflecting mirrors 12 and 13. However, only the exposure section needs to be synchronized at the speed of the reduction ratio. The mass ratio between the reticle stage 2 and the wafer stage 5 is set to 1: 2, and the reticle stage base 6 and the wafer stage base 7 on which both stages are mounted are subjected to reaction force 8 on the same straight line in the scanning direction. Are mechanically connected by The projection lens 3, the reticle stage base 6, and the wafer stage base 7 are composed of a main body structure 11
Is configured.

When performing the projection exposure, the reticle stage 2 and the wafer stage 5 are moved along coordinate axes 9 and 1 of the respective stages.
Synchronous driving is performed in the same Y direction of 0, but both stages accelerate from a stationary state, and after reaching a predetermined speed, maintain a constant speed state for a predetermined time and decelerate. Here, the predetermined speed is a speed at which the reduction magnification ratio is achieved, and the predetermined time is a time during which the exposure section can be sufficiently passed. In addition, the acceleration in the acceleration section and the deceleration section when performing the synchronous driving is performed at an acceleration that is 2: 1 opposite to the mass ratio of both stages. In each of the acceleration section and the deceleration section, each stage generates a driving reaction force. However, since the product of the mass and the acceleration is equal, the stages have the same force, and are offset in the opposite direction on the same line of action across the reaction force receiver 8. You.

On the other hand, in the case of the conventional example shown in FIG.
It escapes from the main body by 8, 109, but cannot be set to 0. For this reason, the residual reaction force is transmitted to the main body structure, causing vibration and deformation. As a result, the accuracy of the projection lens and the measurement system is deteriorated, and the contrast, the resolving power, the alignment accuracy, and the like are reduced.

In the above embodiment, the mass ratio between the reticle stage 2 and the wafer stage 5 is set so that the driving reaction forces generated by both stages are equal, and the reticle stage 2 and the wafer stage 5 act in opposite directions on the same line of action with the reaction force receiver 8 interposed therebetween. By arranging both stages, it was possible to completely offset the reaction force. As a result, the reaction force was not transmitted to the projection lens and the main body structure supporting the measurement system, which led to improvements in contrast, resolution, and alignment accuracy.

In FIG. 1, the mass ratio between the reticle stage 2 and the wafer stage 5 is 1: 2, but may be 1: 4 which is the reciprocal of the reduction ratio. Then, the acceleration ratio between the acceleration section and the deceleration section can be set to 4: 1, which is the same as the ratio between the two stages in the constant velocity section.

Although the reflecting mirrors 12 and 13 are shown as plane mirrors in FIG. 1, the optical path can be bent by an arbitrary mirror surface such as a spherical surface or a lens.

[Embodiment of Device Production Method] Next, an embodiment of a device production method using the above-described exposure apparatus will be described. FIG. 3 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel, a CCD, a thin film magnetic head,
2 shows a flow of manufacturing a micromachine or the like. Step 1
In (Circuit Design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. Step 3 (wafer manufacturing)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
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 prepared 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. 4 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 1
In 5 (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 production method of this embodiment, it is possible to produce a highly integrated device at a low cost, which was conventionally difficult to produce.

[0026]

According to the present invention, the reaction force of the reticle stage and that of the wafer stage are made equal to each other, and the arrangement of the reticle stage and the wafer stage make it possible to cancel the reaction force. Vibration and deformation can be reduced, and as a result, contrast, resolution and alignment accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration of a projection exposure apparatus according to an embodiment of the present invention, which can cancel a driving reaction force of a reticle stage and a wafer stage.

FIG. 2 is a schematic diagram showing a configuration of a conventional step-and-scan type projection exposure apparatus.

FIG. 3 is a flowchart of manufacturing a micro device.

FIG. 4 is a detailed flowchart of a wafer process.

[Explanation of symbols]

1: reticle, 2: reticle stage, 3: projection lens, 4: wafer, 5: wafer stage, 6: reticle stage base, 7: wafer stage base, 8: reaction force receiving,
9, 10: coordinate axes of each stripe, 11: body structure, 1
2, 13: reflecting mirror, IL: slit illumination light.

Claims (8)

[Claims] 1. An illumination optical system for illuminating a predetermined illumination area of an original, a projection optical system for projecting an original pattern in the illumination area onto a substrate at a predetermined magnification, and a predetermined direction with respect to the illumination area. A projection stage having a movable original stage and a substrate stage movable in a predetermined direction in synchronization with the original stage with respect to an exposure area conjugate with the illumination area, wherein the original stage and the substrate stage Wherein the force generated by the original stage and the force generated by the substrate stage are the same when moving in synchronization with each other. 2. The product of the mass of the original stage and the acceleration of the original stage at each moment when the original stage and the substrate stage move synchronously, the product being equal to the product of the mass of the substrate stage and the acceleration of the substrate stage. The projection exposure apparatus according to claim 1, wherein: 3. The projection according to claim 1, wherein both stages are arranged such that a force generated when the original stage and the substrate stage move synchronously is canceled. Exposure equipment. 4. The projection exposure apparatus according to claim 1, further comprising a mechanism for canceling a reaction force generated when the original stage and the substrate stage move synchronously. . 5. The two stages are arranged on the same line of action and in opposite reaction directions so that reaction forces during synchronous movement of the original stage and the substrate stage are offset. The projection exposure apparatus according to claim 3, wherein 6. The projection exposure apparatus according to claim 1, wherein the original on which the pattern is formed is a mask substrate or a reticle substrate. 7. The projection exposure apparatus according to claim 1, wherein the substrate on the stage is a photosensitive substrate or a semiconductor wafer substrate. 8. A device manufacturing method, comprising manufacturing a device using the projection exposure apparatus according to claim 1.