JPH118181A - Projection-type aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain a pattern from getting out of position so as to enhance it in positional accuracy in a projection-type aligner by a method wherein vibrations conducted to a reticule stage through the intermediary of a frame when a stage is driven are canceled. SOLUTION: Vibrations induced when a stage 8 is driven are detected, a controller 4 inverts the above vibrations in waveform to generate vibrations of new waveform mode so as to cancel the former vibrations, the vibrations of new waveform mode are converted into a voltage of the same waveform mode with the vibrations, and the voltage signals are applied to a piezoelectric element as a vibrator 1. Vibrations conducted to a reticule stage 12 are canceled with the vibrator 1 where the voltage signals are applied, whereby a reticule 11 is always kept at a fixed position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type exposure apparatus for transferring a pattern of a reticle onto a semiconductor substrate while reducing the size of the reticle, and more particularly, to removing vibration transmitted to a reticle arrangement portion when a stage on which the semiconductor substrate is mounted is moved. The present invention relates to a projection type exposure apparatus having a vibration isolation function.

[0002]

2. Description of the Related Art In recent years, with the increasing integration of semiconductor devices and miniaturization of patterns, there has been a demand for high exposure device resolution and stage positioning accuracy in exposure apparatuses. However, even if the accuracy of each part of the exposure apparatus itself is improved, even a slight vibration from the floor on which the exposure apparatus is installed may be transmitted to the inside of the exposure apparatus, degrading the pattern overlay accuracy and causing exposure failure. To avoid this, this type of exposure apparatus is usually installed on a vibration isolation table that absorbs vibration from the floor and does not transmit vibration to the apparatus main body.

[0003] This vibration isolating table has means for absorbing vibration from the floor surface, such as a coil spring and a dash pot. Then, these vibrations are absorbed by the vibration absorbing or damping means so as not to be transmitted to the apparatus main body.

However, when the accuracy of alignment in recent exposure is required to be 0.25 μm, the influence of vibration due to the movement of the inside of the apparatus, particularly, the stage on which the wafer is mounted cannot be ignored. The vibration generated inside this apparatus greatly affects the transfer accuracy, and has become a serious problem.

[0005] A vibration isolating table for suppressing the vibration generated by the device itself is disclosed in Japanese Patent Application Laid-Open No. Hei 7171516. In this vibration isolating table, an electromagnet is arranged so as to face a lower base of the apparatus, and after inputting a vibration signal generated inside the apparatus such as an XY stage mechanism and performing signal processing, the electromagnet is magnetized to vibrate the lower base. Restrained. When the drive signal of the XY stage is stopped, the electromagnet is demagnetized to absorb vibration from the floor.

[0006]

However, in the above-described vibration isolating table, although the vibration caused by the driving of the stage can be suppressed to some extent at the stage portion, the reticle disposed at a position distant from the stage has the stage. Since the stage is mounted on the frame in the same manner as described above, the vibration of the stage is transmitted to the frame and the position of the reticle changes. Then, since the reticle pattern whose position has changed is transferred to the wafer, a shift occurs between the position of the pattern to be transferred to the wafer and the transferred pattern.
For this reason, there is a problem that a deviation occurs in the superposition of the transferred pattern and accurate exposure cannot be performed.

Accordingly, it is an object of the present invention to provide a projection type exposure apparatus having an anti-vibration mechanism capable of eliminating vibration transmitted to a reticle when a stage is driven.

[0008]

A feature of the present invention is that a stage on which a semiconductor substrate is mounted, a projection lens for projecting exposure light onto a reticle on which a pattern is formed, and a pattern image of the reticle are reduced. An exposure apparatus including a projection lens that forms an image on the semiconductor substrate, and stores a vibration sensor that detects a vibration generated when the stage is driven and transmitted to the reticle arrangement portion, and a vibration waveform signal detected by the vibration sensor. And a controller for inverting the waveform of the vibration waveform to form a new vibration waveform for excitation and outputting a voltage waveform corresponding to the vibration waveform for excitation, and inputting the voltage waveform and applying the reticle arrangement portion to the controller. A projection-type exposure apparatus including a vibrating piezoelectric element. Preferably, the vibration sensor has a piezoelectric element having the same characteristics as the piezoelectric element.

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a view showing a projection type exposure apparatus according to an embodiment of the present invention. As shown in FIG. 1, the projection type exposure apparatus detects a vibration generated when the stage 8 on which the wafer 13 is mounted is driven, and receives a signal from the vibration sensor 2 and stores the signal as a vibration waveform. The controller 4 outputs a voltage waveform signal corresponding to the vibration waveform by newly advancing or delaying the phase of the vibration waveform stored with the controller 4, and the controller 4 attached to the fixed support 6 and And a vibration sensor 3 that measures the vibration of the reticle stage 12 by inputting a voltage waveform signal output from the reticle stage 12 and vibrating the reticle stage 12.

As the vibration sensor 2, an electro-dynamic vibration sensor combining a magnet and a movable coil or a piezoelectric vibration sensor using a piezoelectric element is used. Also, a vibrator 1 as an actuator
Uses a piezoelectric element which can obtain a larger force per volume than a hydraulic cylinder and has a fast response. Considering that a piezoelectric element is used for the vibrator 1, it is necessary to use a piezoelectric sensor having a piezoelectric element having the same characteristics as the piezoelectric element of the vibrator 1 for the vibration sensors 2 and 1, such as a converter. Control becomes easier.

FIG. 2 is a waveform chart for explaining the image stabilizing operation of the projection type exposure apparatus of FIG. Next, the anti-vibration operation of the projection type exposure apparatus will be described with reference to FIGS. First, in advance, while the wafer 13 is mounted on the stage 8, the stage 8 is moved to investigate a vibration mode in the reticle stage 12. For this purpose, the stage is stepped to generate vibration in the stage 2. The vibration caused by the stage 8 at this time is as shown in FIG.
It is detected by the vibration sensor 2 as a sine waveform gradually attenuated with time.

Although the frame 5 of the exposure apparatus is originally rigid to maintain accuracy, the vibration transmitted to the reticle stage 12 is delayed by Δt. In addition, since the position of the reticle stage 12 is above the center of gravity of the frame 5, the vibration transmitted from the stage 8 is inverted, resulting in an inverted sine waveform as shown in FIG. This vibration waveform is detected by the vibration sensor 3. Then, the vibration mode of the reticle stage 12 is stored in the storage unit of the controller 4 for a time.

Next, the stage 8 is again stepped in the same manner as the previous time. The drive signal of the stage feed at this time is input to the controller 4 to start measurement and vibration. As a result, the vibration mode waveform stored in the controller 4 is extracted and transferred to the phase adjuster of the controller 4, where the phase of the vibration mode waveform is changed. Then, the vibration waveform whose phase has been changed is formed into a signal waveform in which the waveform of FIG. Further, this signal waveform is formed into a voltage waveform as shown in FIG.

The obtained voltage waveform is supplied to a piezoelectric element which is the vibrator 1. The piezoelectric element receives this voltage waveform, and as shown in FIG. 2C, the piezoelectric element vibrates with an amplitude proportional to the voltage to vibrate the reticle stage 12. This cancels the vibration of FIG. 2B in which the vibration of the piezoelectric element is transmitted from the stage 8, and the vibration sensor 3 detects the vibration of FIG.
As shown in (d), a smooth vibration having a low peak value of the waveform is detected.

If the waveform peak value does not decrease as shown in FIG. 2D, the gain of the low-frequency amplifier of the controller 4 is adjusted or the phase angle is adjusted by a phase adjuster. As shown in 2 (d), the waveform peak value is made low and smooth. If the rigidity of the frame 5 is low and Δt is long, a delay circuit that delays by Δt may be provided to delay the input of the drive start signal.

Thus, the vibration from the stage is obtained,
If this vibration mode is converted into a voltage waveform and applied to the piezoelectric element, the reticle stage 11 cancels the vibration and sets a voltage waveform to be supplied to the vibrator 1 so that the reticle 11 remains stationary, and performs actual exposure. By operating the anti-vibration mechanism every time, the positional shift of the pattern transferred from the reticle 11 to the wafer 13 is eliminated.

In this embodiment, the elimination of vibration from the reticle stage has been described. However, when the projection lens 9 is greatly affected by vibration due to the structure of the frame or the like, the vibrator vibrates the housing of the projection lens. And the vibration transmitted from the stage should be canceled.

[0019]

As described above, according to the present invention, a vibration waveform generated at the time of starting the stage and transmitted to the reticle stage is stored as a waveform mode, and the waveform is inverted so as to cancel the vibration and a vibration waveform having a new waveform mode is provided. By converting the voltage into a voltage waveform corresponding to the vibration waveform and supplying the voltage to the piezoelectric element, the piezoelectric element cancels the vibration transmitted to the reticle stage, and the reticle stage can always be kept stationary to stabilize the reticle. As a result, there is an effect that the yield can be improved without displacement of the reticle pattern transferred to the wafer.

[Brief description of the drawings]

FIG. 1 is a view showing a projection type exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining an image stabilizing operation of the projection type exposure apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exciter 2, 3 Vibration sensor 4 Controller 5 Frame 6 Support body 7 Anti-vibration stand 8 Stage 9 Projection lens 10 Light projection lens 11 Reticle 12 Reticle stage 13 Wafer

Claims (2)

[Claims] 1. A stage on which a semiconductor substrate is mounted, a projection lens for projecting exposure light onto a reticle on which a pattern is formed, and a projection lens for reducing a pattern image of the reticle to form an image on the semiconductor substrate. An exposure apparatus comprising: a vibration sensor that detects vibration generated when the stage is driven and transmitted to the reticle arrangement portion; and stores a vibration waveform signal detected by the vibration sensor and inverts the waveform of the vibration waveform. It is characterized by comprising a controller that newly forms a vibration waveform for excitation and outputs a voltage waveform corresponding to the vibration waveform for excitation, and a piezoelectric element that inputs the voltage waveform and vibrates the arrangement portion of the reticle. Projection type exposure apparatus. 2. The projection type exposure apparatus according to claim 1, wherein the vibration sensor has a piezoelectric element having the same characteristics as the piezoelectric element.