JPH04144114A - Aligner - Google Patents

Abstract

PURPOSE:To damp the vibration of a device body within a short period of time and to make exposure of high throughput possible with high accuracy, by guiding a laser beam in the device and detecting the relative position of the device body to the light source, and by controlling the drive of the actuator of a servo mount so that both may have a specified positional ]relation based on the relative positional deviation signal. CONSTITUTION:A stage X or Y 8, 9 makes a step by a driving signal from a controller 31, an alignment scope 2 makes final positional measurement, and positioning is completed by the feedback of the signal. Meanwhile, the vibration is measured by a mount 12, fed back to the mount controller 32, and suppressed quickly. Next, the relative position of the aligner body to a light source device placed detached is detected by an optical axis position detector 13, and the device body is positioned by controlling the actuator for the mount based on the position signal put in the mount controller 32. When the controller 31 receives completion signals from both 2, 32, it outputs a command signal for emitting light, and a wafer 7 is irradiated with a laser beam and exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exposure apparatus used in semiconductor device manufacturing, etc., and more specifically, an exposure apparatus having an actuator for positioning the absolute or relative position of the apparatus main body in an exposure apparatus support part. This relates to an exposure device.

[Prior Art] The miniaturization and higher integration of semiconductor devices continue to progress without stopping. The main type of exposure equipment used in the manufacture of semiconductor devices is a stepper, which is a sequentially moving projection exposure apparatus, and it is predicted that it will continue to dominate in the manufacture of ultra-fine devices in the future.

Therefore, there will be an even stronger demand for improving the resolution of steppers in order to miniaturize elements.

The resolving power is expressed by the foot of Rayleigh's equation, Re=k·λ/NA. Therefore, conventionally, the exposure wavelength was changed to g-line (wavelength 4
The numerical aperture (NA) of the projection lens remains fixed at 36 nm).
) to improve resolution. However, as the NA increases, the depth of focus decreases, and the design and manufacturing of projection lenses have reached their limits, so the wavelength of exposure light must be shortened in order to support the future submicron generation. It's coming. Currently i-line (wavelength 365nm)
Steppers have entered the stage of practical use, and the next generation of excimer steppers using a KrF excimer laser (wavelength 248 nm) as a light source is seen as promising.

However, when putting excimer steppers into practical use, there are problems that do not exist with conventional steppers. An excimer laser light source is a considerably larger light source unit than a high-pressure mercury lamp light source that emits G-line or 1-line light. Therefore, if the excimer laser light source is mounted on the main body of the exposure apparatus as in the prior art, this increases the size and weight of the exposure apparatus, which is not practical. Therefore, an effective countermeasure is to place the light source separately from the stepper body. However, by separating the stepper main body and the light source in this way, the relative positional relationship between the two greatly affects the basic performance of the exposure apparatus. For example, a change in the relative positional relationship due to a change in the posture of the stepper causes an optical axis deviation or an incident angle deviation of the laser beam. The resulting uneven illuminance causes problems such as deterioration of exposure accuracy and reduction in throughput due to deterioration of illuminance.

There are countermeasures such as increasing the diameter of the laser beam, but this results in a disadvantage of decreasing throughput.

On the other hand, one way to improve resolution, throughput, and alignment accuracy is to improve stepper vibration damping technology. Vibrations that pose problems in steppers include vibrations transmitted from the surrounding environment (floor, etc.) and vibrations generated from movable parts within the device. Conventionally, as a technique for suppressing these vibrations, a vibration isolating table has been used in which a mount portion that supports the apparatus main body has a spring force and a damping force. That is, vibrations from the floor are suppressed by lowering the spring constant of the mount to lower the resonant frequency of the device and widening the vibration isolation area to suppress the transmission rate. Furthermore, with respect to vibrations generated inside the device, the vibration energy is dissipated by increasing the damping rate of the mount, achieving stable convergence in a short time.

Furthermore, in recent years, instead of the above-mentioned simple mounts with a fixed spring constant and damping rate, mounts that have a feedback control system and generate variable restoring force (hereinafter referred to as servo mounts) have become commercially available.

This servo mount uses an actuator using electromagnetic force or fluid pressure to generate a phase-corrected force that strengthens vibration damping based on the measured acceleration of the device body supported by the mount, making the device resonance-free. It is designed to have a vibration damping effect and is currently used as a vibration damping support device for F# dense equipment.

These simple mounts and servo mounts have been effective in damping vibrations of devices, but when the target is a stepper, the following problems arise. In the stepper, the XY stage on the device moves in steps, so the center of gravity of the device body changes sequentially. Therefore, when the conventional mount described above is used as a vibration damping support device, a static posture change due to a change in the center of gravity of the stepper remains in principle after the vibrations generated in each step operation are attenuated.

Therefore, when using the separately installed light source mentioned above,
This change in the posture of the stepper leaves a change in the relative position between the light source device and the stepper, which causes optical axis deviation in the laser light section.

[Problem to be solved by the present invention] In some conventional examples, the vibration damping mount is equipped with an auto-leveling mechanism in order to maintain the horizontal level of the device body.
In the case of a mount using an air spring, multiple mount legs independently open the valve using a mechanical mechanism in proportion to the amount of deviation from the set value of the vertical position, thereby maintaining the horizontal position of the device body. ing.

However, in this conventional example, it is difficult to achieve the posture holding accuracy of several hundred μm required for an excimer stepper due to hysteresis of the mechanical mechanism. Furthermore, the vibration damping mount described above cannot handle positioning not only in the vertical direction but also in the horizontal direction.

Further, even in the case of a servo mount that has a feedback control system for damping vibrations, the purpose of the control is to quickly converge vibrations, so there is no servo mount that focuses on position control.

In view of the above-mentioned problems with the conventional type, the present invention dampens the vibrations of the main body of the exposure device in a short time, and also prevents deterioration of exposure accuracy due to changes in the relative position between the separately installed light source and the main body of the exposure device. It is an object of the present invention to provide a high-precision, high-throughput exposure device that suppresses deterioration of light illuminance.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides a step-and-repeat method for drawing on an original plate using a laser beam irradiated from a separately placed light source. In an exposure apparatus that projects and exposes a pattern onto an exposed object through a projection optical system, a mount part that supports the main body of the apparatus includes a sensor that detects vibrations of the main body of the apparatus, and a sensor that attenuates the vibrations according to the output of the sensor. a servo mount having an actuator that generates a force, a detection means for introducing laser light from the light source to detect the relative position of the device main body with respect to the light source, and a relative position deviation output from the detection means. The apparatus is characterized by comprising a control means for driving the actuator so that the main body of the apparatus and the light source are in a predetermined positional relationship based on a signal.

For example, for the mount that supports the main body of the exposure apparatus,
A vibration damping function is provided by adding multiple sensors that detect vibration in three directions: the direction, Y direction, and The actuator is driven by the relative position deviation signal with respect to the exposed light source to control positioning, thereby enabling relative positioning.

According to the configuration of the present invention, in addition to the vibration damping function, the absolute position or relative position (for example, relative position with respect to a separately placed light source) of the main body of the apparatus can be determined.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a front view showing the basic configuration of an exposure apparatus according to an embodiment of the present invention. 2 is a detailed view of the mount portion of this exposure apparatus, FIG. 3 is a plan view of the mount portion showing the arrangement of actuators in the mount portion, and FIG. 4 is a detailed view of the position detection portion of the laser beam introduction port.

In Fig. 1, 1 is the illumination system that guides the laser beam entering from the human light section (laser light introduction KS) to the top of the reticle, and 13 is the optical axis position of the laser beam introduced as part of the illumination system 1. 2 is an alignment scope that detects the reticle position relative to the reticle reference mark and the wafer position relative to the reticle; 3 is a reticle having a pattern to be transferred; 4
5 is a projection lens that reduces and projects the pattern formed on the reticle 3 onto the wafer; 6 is a mirror that supports the projection lens 5, the illumination system 1, and the outer cylinder 4; Cylindrical surface plate, 7 is wafer, 8
9 is an X stage that supports the wafer 7 and is movable in the X direction;
10 is a stage base that supports the X stage 9, and 11 is a base base that supports the lens barrel base 6 and the stage base 10.

In the description of the present invention, the attitude and absolute position of the main body of the device are defined as the values of 6 degrees of freedom (X), assuming that the component supported by the basic surface plate 11 is one rigid body.

It refers to the position expressed in the Y and X directions and the rotational directions of the X, Y and X directions. Reference numeral 12 denotes mounts that support the foundation surface plate 11;
The two units are connected by a frame, which is a characteristic element of this embodiment.

31 is a control device that controls the operation of the entire exposure apparatus;
2 is a mount control device that mainly controls the operation of the four mounts 12, and 33 is a drive device that drives the actuators of each of the four mounts 12.

Next, the operation of this exposure apparatus in the configuration shown in FIG. 1 will be explained.

The wafer 7 is transferred to the XY stage 8 by a wafer transport system (not shown).
．． When the wafer 7 is transferred to the wafer 9, the control device 31 outputs a drive signal for stepping the wafer 7 to the position where the wafer 7 is to be exposed (exposure start position). The X or Y stages 8, 9 step accordingly. At the end of the step, the final position measurement is performed by the alignment scope 2, and the positioning of the stage 8.9 is completed by feedback of the signal.

On the other hand, vibrations from the floor and vibrations due to stage movement are
As will be described later, it is measured by the mount 12 and fed back to the mount control device 32 as an acceleration signal.

This provides quick damping.

Next, a light source device (not shown) (separate from the exposure device main body)
The relative position between the exposure apparatus main body and the exposure apparatus main body is detected by the optical axis position detection section 13 of the laser first light incident section. Optical axis position detection unit 1
The position signal from 3 is input manually to the mount control device 32. Based on this position signal, the mount controller 32 controls the actuator of the mount. Thereby, the positioning of the main body of the apparatus is performed.

When damping and positioning are completed, the mount control device 32 sends a completion signal to the control device 31. Alignment scope 2
After receiving the completion signal from the mount control device 32, the control device 31 issues a command signal for the light source device, which is a laser light source, to emit light. 3. The light is irradiated onto the wafer 7 through the projection lens 5, thereby exposing the wafer 7.

Further, with reference to FIGS. 2 and 3, the mount 12 of the exposure apparatus shown in FIG. 1 will be described in detail. Note that in these figures, the same numbers as in FIG. 1 indicate the same members.

The exposure apparatus of this embodiment includes four mounts 12. Each mount 12 is fixed by a mount frame 20. Each mount 12 has a three-way actuator. As the Z direction (vertical direction, perpendicular to the paper surface of FIG. 3) actuator 18, an air spring actuator or the like can be used. Also,
As the X-direction actuator 14 and the Y-direction actuator 15, it is possible to use a voice coil type actuator, an air cylinder type actuator, an air spring actuator, or the like.

Actuators 14 in these X, Y, and Z directions 15.
18 requires a structure that releases forces in five degrees of freedom. In this embodiment, the following steps are performed.

First, in the Z direction, the air spring 18 is attached to the mount frame 2 with the laminated rubber 16 in between, similar to the conventional servo mount.
It is designed to be elastically supported at 0. As a result, X, Y
Thrust force in the direction and rotational force in the X, Y, and Z directions are released. In addition, in the X direction and the Y direction, since the four mounts 12 are fixedly supported by the mount frame 20, the force application point of the foundation surface plate 11 is connected from the actuator 14.15 via the rod 21. I have to.

Thereby, thrust force and rotational force are absorbed and released by deformation of the rod 21. At present, the change in the attitude of the main body of the exposure apparatus can be reduced to a maximum of several millimeters based on the amount of displacement of the mount, so the above mechanism is practically sufficient.

17 is an acceleration pickup, and 19 is a servo valve.

Next, with reference to FIG. 4, the position detection section 13 of the exposure apparatus shown in FIG. 1 will be explained. The figure shows details of a laser light introducing section that is a part of the illumination system 1. Position detection section 13
is a unit that detects the relative position between the light source device and the main body of the exposure apparatus using laser light from the light source device.

At the time of relative position detection, the flip-up mirror 22 is in a raised state. At this time, the incident laser light is a half mirror.
23, the light that goes straight and passes through, and the light that is reflected.
Divided into directions. The laser beam that has traveled straight enters the tilt detection sensor 26 via the Fourier transform lens 24. The tilt detection sensor 26 detects the tilt of the optical axis of the laser beam. The other laser beam enters the position detection sensor 27 via the imaging lens 25. Position detection sensor 2
7 detects the positional deviation of the optical axis of the laser beam. These detection signals are sent to the mount control device 32 and become feedback signals for positioning. At the time of wafer exposure, the flip-up mirror 22 is lowered and operates to guide laser light to the illumination system 1.

Referring again to FIG. 2.3, in the exposure apparatus of this embodiment, an acceleration pickup sensor 16 is used as a sensor for vibration control. The acceleration pickup sensor 17 is attached to a movable part within the mount 12 (a part that is integrated with the base surface plate).

As shown in FIG. 3 of this embodiment, the four mounts 12 are referred to as a first mount 12-1.342, a third mount 12-3, and a fourth mount 12-4. Z-direction acceleration pickups 17 were attached to all four mounts 12. The acceleration pickup 17 in the X direction includes a first mount 12-1 and a third mount 1.
Attached to 2-3. Y-direction acceleration pickup 17
were attached to the second mount 12-2 and the fourth mount 12-4. Signals from these acceleration pickups 17 are fed back to the mount control device 32.

Next, the actuator operations of the four mounts 12 will be explained. Regarding the movement in the Z direction, the X axis, and the Y axis, vibration damping and positioning are performed by the Z direction actuators of the four mounts. Regarding movement in the XY plane, actuators facing each other in the same direction (for example, the X-direction actuator 14 of the first mount 12-1 and the X-direction actuator 14 of the second mount 12-2)
is controlled by the force generated from the four pairs of XY. Regarding movement in the X direction, vibration damping and positioning are performed by two pairs of X direction actuators 14. Similarly,
In the Y direction, two pairs of Y direction actuators 15 perform vibration damping and positioning. Regarding the movement around the Z axis,
Two pairs of X-direction and two pairs of Y-direction actuators 14.
Vibration damping and positioning are performed by force couples that can be generated from 15, respectively.

[Effects of the Invention] As explained above, according to the present invention, vibrations are attenuated in a short time by the servo mount, and the actuator of the mount is controlled by feedback control using the signal from the position detection section of the laser human light section. can be used to position the main body of the device. Therefore, high precision,
Moreover, it has become possible to realize a high-throughput exposure apparatus.

Furthermore, since the position sensor is provided at the inlet from the laser light source, the position sensor can be removed from the mount, reducing the cost of the device and simplifying the mount configuration. Therefore, there is an effect that the mount can be made smaller, and it is also effective as a countermeasure against the relative change over time caused by the drift of the position sensor.

[Brief explanation of drawings]

Figure 1 is an overall view of an exposure apparatus according to an embodiment of the present invention, Figure 2 is a detailed view of the servo mount of the exposure apparatus of Figure 1, and Figure 3 is a servo mount of the exposure apparatus of Figure 1. FIG. 4 is a detailed view of the position detection section that detects the relative position of the laser beam prosthesis section. 1, illumination system, 2 near alignment scope, 3 reticle, 5: projection lens, 7: wafer, 8: x stage, 9: Y stage, 10: stage surface plate, 12: mount, 13: optical axis position detection section, 14: X direction actuator, 15: Y direction actuator, 18: Z direction actuator.

Claims (2)

[Claims] (1) In an exposure apparatus that projects and exposes a pattern drawn on an original plate onto an exposed object via a projection optical system in a step-and-repeat manner using a laser beam irradiated from a separately placed light source, As the mount part that supports the main body part, a servo mount having a sensor that detects vibrations of the apparatus main body part and an actuator that generates a force that dampens the vibrations according to the output of the sensor is used, and a laser beam from the above light source is used. a detection means for detecting the relative position of the apparatus main body with respect to the light source; and a detection means for detecting the relative position of the apparatus main body with respect to the light source, and a predetermined positional relationship between the apparatus main body and the light source based on a relative position deviation signal output from the detection means. An exposure apparatus comprising: control means for driving the actuator. (2) A plurality of the sensors are arranged to detect vibrations of the device main body in the X direction, Y direction, and Z direction, and similarly, the actuator moves the device main body in the X direction, Y direction, and
2. The exposure apparatus according to claim 1, wherein a plurality of exposure apparatuses are arranged so as to damp vibrations and position them in the Z direction and the Z direction.