JP2789706B2 - Exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a stage for an exposure apparatus, the length of a protective cylinder constituting a laser length measuring system is set to a fixed length so that the operation of a coarse movement stage does not affect the fine movement stage. A coarse stage, a fine stage, a coarse stage measuring device for measuring the position of the coarse stage, and a fine stage fixed to the fine stage. An exposure apparatus comprising: a mirror; an interferometer; and a laser length measurement system for measuring a position of a fine movement stage including a protection tube having an end in contact with each of the mirror and the interferometer, wherein the holding table is rough. The coarse stage is mounted on the fine stage via a support mechanism, the coarse stage operates on the fine stage, and the fine stage is not affected by the operation of the coarse stage. Equipment stay Constituting the exposure apparatus to have.

[Industrial applications]

The present invention relates to a stage for an exposure apparatus, and more particularly to a stage structure capable of measuring a length with high accuracy by a laser interferometer without being affected by atmospheric fluctuations.

In recent years, along with the miniaturization and high integration of electronic devices centering on semiconductor integrated circuits, miniaturization of patterns, for example,
It has entered the submicron region of 0.5 μm.

Along with this, development of each main fine processing technology for forming a fine pattern is being vigorously performed in various places.

Among various processing techniques for performing fine patterning, a patterning technique based on photoetching, which is generally called photolithography (photolithography), is currently most utilized.

One of the elemental technologies in the patterning technology by photoetching is an exposure technology.

Depending on the type of light source (ray source), the exposure technology includes ultraviolet exposure that has been conventionally used for general transfer, X-ray exposure that uses X-rays as a light source that is expected in the future, and charging. Since it is a particle beam, it can be deflected by an electromagnetic field and can be classified into electron beam exposure using an electron beam as a light source and ion beam exposure using an ion beam light source used not only for transfer but also for direct writing.

However, whichever exposure method is used, high-precision position control of the stage that supports and moves the wafer or mask, which is the object to be exposed, is indispensable, and high-precision control of 0.005 μm or less is required. Have been.

[Conventional technology]

Generally, a stage capable of performing position control with high accuracy has a configuration in which a coarse movement stage and a fine movement stage are combined.

The coarse movement stage is mechanically driven, while the fine movement stage is, for example, a piezoelectric actuator utilizing electro-mechanical conversion of a piezoelectric body.

Also, for measuring the movement amount, for the coarse movement stage,
For example, a magnetic linear scale is used, and a laser measuring system is generally used for the fine movement stage.

 FIG. 3 is a structural view of a conventional stage.

In the figure, 40 is a coarse stage guide, 4 is a coarse stage, 5 is a fine stage, 3 is a holding table, 2 is an object to be exposed,
Reference numeral 61 denotes a mirror, and reference numeral 6 denotes a laser length measurement system including the mirror 61.

First, the coarse movement stage 4 is arranged on the coarse movement stage guide 40, and the coarse movement operation is performed.

Next, a fine moving stage 5 is arranged on the coarse moving stage 4, and the holding table 3 placed on the fine moving stage 5 is provided.
The object 2 to be exposed, for example, a wafer, is attracted to move finely.

On the other hand, a mirror 61 is attached to the fine movement stage 5, and the length of the fine movement amount is measured by the laser length measurement system 6 based on the mirror 61.

For the laser length measuring system 6, a two-frequency laser interferometer is widely used.

The dual-frequency laser interferometer uses two laser beams with different wavelengths emitted from a dual-wavelength Zeeman laser.
The beam is split into reference light and measurement light by the beam splitter.

The length measuring light is further divided into two by a polarizing beam splitter, and the reference light having passed through the retroreflector for position reference and the length measuring having frequency shifted by the Doppler effect through the retroreflector for moving position. Become light.

The amount of frequency shift is integrated over time to determine the amount of displacement of the retroreflector for position measurement, that is, the amount of movement of the fine movement stage 5. In the laser length measuring system 6 shown in FIG. 3, a plane mirror is used for the retroreflector for position measurement.

By the way, when this dual-frequency laser interferometer is used in the atmosphere, it is known that the measured value is affected by the temperature, pressure, humidity and the like of the atmosphere. This is due to the fact that the refractive index of the atmosphere changes with these environmental parameters.

In order to reduce the influence of these environmental parameters, the entire length measuring system is put in a thermostat to stabilize the environment. Alternatively, on the premise that the environmental parameters are homogeneous near the length measuring section, they are measured by appropriate means, and the measured values are corrected using mathematically given mathematical expressions.

However, if an attempt is made to achieve a high accuracy of, for example, 10 ^-6 or less with respect to the length being measured, since the atmosphere in the laser beam path 64 cannot be homogeneous, subtle fluctuations in the atmosphere are measured. The effect on the value becomes a problem.

As an example, in a normal laboratory environment, about 200m
The repeatability of the measured value when measuring the fixed distance of m
It is experimentally known that the result is as bad as 0.1 μm or less. The resolution of the laser interferometer itself is 0.0025μ
This can be said to be a serious problem, since about m meters have been produced.

Therefore, conventionally, a method has been attempted in which the path 64 of the laser beam for length measurement is covered with the protective cylinder 63 so as to be less affected by the atmosphere.

[Problems to be solved by the invention]

As described above, the fluctuation of the atmosphere, which is the path of the laser beam for length measurement, affects the length measurement value, even though the length measurement accuracy of the laser interferometer itself is very high. Therefore, in order to prevent this effect, the path of the laser beam is covered with a cylindrical member.

However, in the conventional stage structure, the fine movement stage also moves in conjunction with the movement of the coarse movement stage, so that the position of the mirror provided on the fine movement stage for laser measurement is greatly changed.

Therefore, a cylindrical member having a large stroke elasticity in the longitudinal direction and high rigidity in a direction perpendicular to the longitudinal direction has been required.

However, realizing such a cylindrical member has been a difficult problem.

The present invention first reverses the conventional stage structure so that the operation of the coarse movement stage does not affect the fine movement stage.

In addition, the length fluctuation of the laser beam path for the length measurement of the laser length measurement system used for position measurement of the fine movement stage is shortened, and the length of the cylindrical member covering the path is fixed, so that the influence of atmospheric fluctuations is reduced. The purpose of the present invention is to provide a novel stage structure that can avoid the problem.

[Means for solving the problem]

The problems described above include: a holding table onto which an object to be exposed is sucked; a coarse movement stage; a fine movement stage; a coarse movement stage length measuring device for measuring the position of the coarse movement stage; Mirror, interferometer,
A laser measuring system for measuring the position of a fine movement stage comprising a protection cylinder having an end in contact with each of the mirror and the interferometer, and an exposure apparatus having: The coarse movement stage is mounted on a fine movement stage via a support mechanism, the coarse movement stage operates on the fine movement stage, and the fine movement stage is a stage for an exposure apparatus which is not affected by the operation of the coarse movement stage. An exposure apparatus configured to have, or a holding table is mounted on a holding mechanism, the holding mechanism is removably supported on a coarse movement stage, a fine movement stage is removably supported on the holding mechanism, and the fine movement stage Is solved by an exposure apparatus configured to have an exposure apparatus stage that is not affected by the operation of the coarse movement stage.

(Operation)

As described above, in the conventional exposure apparatus stage, the fine movement stage is also largely moved in conjunction with the large operation of the coarse movement stage, so that the length of the protective cylinder constituting the laser length measurement system is reduced. For example, if it is not variable length,
The path of the laser beam was not sufficiently covered. Moreover, it was very troublesome to make a variable-length protective cylinder. On the other hand, in the present invention, even if a protective cylinder having a fixed length is used, the path of the laser beam can be sufficiently covered.

That is, in the laser measurement system, the length measurement is performed while the laser beam emitted from the interferometer reciprocates in the protection cylinder and is reflected on the mirror provided on the fine movement stage. Is, for example, at most 10
Since it is about 0 μm, the operation range of the coarse movement stage is overlaid on the fine movement stage, so that the operation range of the fine movement stage is not increased.

In one means for realizing such an operation relationship between the coarse movement stage and the fine movement stage, a fine movement stage is mounted on the coarse movement stage, and a holding table for sucking an object to be exposed is mounted on the fine movement stage. Instead of the conventional stage for the exposure apparatus to be mounted and positioned, first, the coarse movement stage is operated, and the object to be exposed is independent of the fine movement stage, for example, with a precision of about 0.5 μm using a magnetic linear scale. They are roughly positioned.

Next, the position is finely adjusted by the fine movement stage on which the coarse movement stage is mounted.

In this case, since the operation of the coarse movement stage does not affect the fine movement stage at all, the length of the protective cylinder constituting the laser measuring system only needs to consider the original operation range of the fine movement stage itself. This means that the path of the laser beam can be sufficiently covered even if the length of the protection cylinder is substantially fixed.

In another realization means, a holding table for adsorbing an object to be exposed is placed on a holding mechanism detachably mounted on a coarse movement stage, while the holding mechanism is configured to move a fine movement stage. It can be detachably supported.

Then, first, the holding table is brought into contact with the holding mechanism, and the coarse movement stage is operated while the fine movement stage is detached,
The object to be exposed is roughly positioned via the holding mechanism irrespective of the fine movement stage. Next, the contact between the coarse movement stage and the holding mechanism is released, and the holding mechanism and the fine movement stage are brought into contact with each other, so that the fine movement stage finely adjusts the position of the object to be exposed placed on the holding mechanism. .

In this case, since the large movement due to the operation of the coarse movement stage does not affect the fine movement stage, the length of the protection cylinder can be fixed, and as a result, the path of the laser beam can be sufficiently covered. .

According to the exposure apparatus of the present invention, the absolute position accuracy of an object to be exposed such as a wafer, for example, with respect to an interferometer is limited by the position accuracy of the coarse movement stage.

By the way, in an exposure apparatus, in particular, in an apparatus for transferring a pattern of a mask such as an X-ray exposure apparatus, a mark on a mask is precisely aligned with a mark on a wafer, or a change in the position of the wafer with respect to the mask ( Shaking) is required to be reduced.

In response to this requirement, the absolute position accuracy of the object to be positioned positioned by the coarse movement stage is determined, for example, by setting each of the mask and the object to be exposed in a mark capture range (cap challenge) of an alignment device (alignment device). It is sufficient that the marked mark enters.

Therefore, the absolute position accuracy of the coarse movement stage described above is an accuracy that sufficiently satisfies the absolute position accuracy.

〔Example〕

FIG. 1 is an explanatory view of one embodiment of the present invention, and FIG. 2 is an explanatory view of another embodiment of the present invention. FIG. 1 (A) shows a coarse movement operation, and FIG. 1 (B) shows a fine movement operation. It is time.

Embodiment 1 In FIG. 1, the coarse movement stage 4 is mounted on a fine movement stage 5 via a support mechanism 7. This support mechanism 7
Is constituted by coarse movement means comprising an air slide and a linear motor, and holding means comprising a vacuum suction pad. On the support mechanism 7, a holding table 3 composed of a vacuum suction pad is provided so that the object 2 such as a wafer can be suction-held.

The position of the coarse movement stage 4 with respect to the fine movement stage 5 can be measured by a coarse movement stage length measuring device 41 composed of a magnetic linear scale provided on the fine movement stage 5. Connected to the servo operation system.

The fine movement stage 5 has a movement stroke of about 100μ.
The actuator is finely moved by the m piezoelectric actuators.

On the other hand, the movement amount of the fine movement stage 5 is constituted by a mirror 61 fixed on the fine movement stage 5, an interferometer 62, and a protection cylinder 63 covering a path 64 of a laser beam connecting the mirror 61 and the interferometer 62. The measurement is performed by the laser measuring system 6. The laser length measuring system 6 is connected to a servo operation system for a fine movement (not shown).

However, since the movement stroke of the fine movement stage 5 is very small, the path 64 of the laser beam can be almost completely covered by using a cylinder having a rigid metal length fixed to the protection cylinder 63.

As a result, it was confirmed that the accuracy of the laser measuring system 6 can be sufficiently obtained by preventing the influence of atmospheric fluctuation on the path 64 of the laser beam.

Embodiment 2 In FIG. 2 (A), the coarse moving stage 4 is mounted on a coarse moving portion guide 42 and can be moved by an air slide and a linear motor (not shown). And
On the coarse movement stage 4, a holding mechanism 8 is detachably supported by vacuum suction via a coarse movement arm 43.
Further, on the holding mechanism 8, a holding table 3 made of a vacuum suction pad is provided, and for example, the object 2
Can be held by suction.

On the other hand, a donut-shaped fine movement stage 5 is also mounted on the donut-shaped fine movement section guide 51 from which the coarse movement arm 43 can escape, and can be moved by fine movement means including a piezoelectric actuator (not shown). Has become.
The fine movement stage 5 and the holding mechanism 8 can be detachably supported by vacuum suction.

The position of the coarse movement stage 4 is provided on the coarse movement portion guide 42 and can be measured by a coarse movement stage length measuring device 41 composed of a magnetic linear scale.

The fine movement stage 5 has a movement stroke of about 100μ.
The actuator is finely moved by a voltage actuator of m.

Further, the movement amount of the fine movement stage 5 is performed by the laser length measuring system 6 having the same configuration as that of the first embodiment.

The coarse movement operation is performed by moving the coarse movement stage 4 while the holding mechanism 8 is lifted up by the coarse movement arm 43 and separated from the fine movement stage 5 and the holding mechanism 8 is coupled to the coarse movement arm 43. I have.

Next, in FIG. 5B, the fine movement operation is performed by moving the fine movement stage 5 in a state where the coarse movement arm 43 is separated from the holding mechanism 8 and the holding mechanism 8 is attracted to the fine movement stage 5. Has become.

In this fine movement operation, since the movement stroke of the fine movement stage 5 is very small, the protection cylinder 63 is made of metal and has high rigidity and a fixed length, so that the path 64 of the laser beam is almost completely formed. Could be covered.

As a result, similarly to the first embodiment, the path 64 of the laser beam
It was confirmed that the influence of the fluctuation of the atmosphere at the time of was prevented, and that the accuracy of the laser measuring system 6 could be sufficiently brought out.

Here, coarse movement means including an air slide and a linear motor and fine movement means including a piezoelectric actuator are used as the movement means for the coarse movement stage and the fine movement stage, however, these drive means can be variously modified. is there.

Further, the effect of the present invention can be exerted only by using the laser measuring system for measuring the position of the fine movement stage. However, in addition to the plane mirror, various retro reflectors (reverse Reflecting mirror) can be used.

Further, the length measurement of the position of the coarse movement stage is not limited to a magnetic linear scale such as Magnescale (trademark), and various modifications are possible.

[Effects of the Invention] As described above, according to the exposure apparatus of the present invention,
When the object to be exposed moves coarsely and largely by the coarse movement stage, the operation of the coarse movement stage can have no influence on the fine movement stage. Therefore, since the movement range of the coarse movement stage is not added to the operation range of the fine movement stage, it can be suppressed to about 100 μm, which is the original operation range of the fine movement stage itself.

Therefore, in the laser measuring system used for measuring the position of the fine movement stage, a rigid cylinder having a fixed length can be used as the protective cylinder covering the path of the laser beam. As a result, the laser beam can be stably covered over almost the entire length of the path of the laser beam.

As a result, it becomes possible to prevent the measurement accuracy of the position of the fine movement stage from being deteriorated due to the influence of the fluctuation of the atmosphere due to the laser beam, and the present invention has developed the fine patterning technology centered on the manufacture of semiconductor devices. It greatly contributes to

[Brief description of the drawings]

 FIG. 1 is an explanatory view of one embodiment of the present invention, FIG. 2 is an explanatory view of another embodiment of the present invention, and FIG. 3 is a structural view of a conventional stage. In the drawing, 1 is an exposure apparatus stage, 2 is an object to be exposed, 3 is a holding table, 4 is a coarse movement stage, 41 is a coarse movement stage length measuring instrument, 42 is a coarse movement section guide, 43 is a coarse movement arm, 5 Is a fine moving stage, 51 is a fine moving section guide, 6 is a laser measuring system, 61 is a mirror, 62 is an interferometer, 63 is a protective cylinder, 64 is a laser beam path, 7 is a supporting mechanism, and 8 is a holding mechanism. .

Claims (2)

(57) [Claims] A holding table (3) on which an object (2) to be exposed is sucked.
A coarse movement stage (4); a fine movement stage (5); a coarse movement stage length measuring device (41) for measuring the position of the coarse movement stage (4); and a fine movement stage (5). Mirror (61),
A laser measuring system for measuring the position of the fine movement stage (5), comprising an interferometer (62) and a protective cylinder (63) whose end is in contact with each of the mirror (61) and the interferometer (2). (6) An exposure apparatus comprising: the holding table (3) is mounted on the coarse movement stage (4); and the coarse movement stage (4) is moved by a fine movement via a support mechanism (7). The exposure is carried on a stage (5), wherein the coarse movement stage (4) operates on the fine movement stage (5), and the fine movement stage (5) is not affected by the operation of the coarse movement stage (4). Equipment stage (1)
An exposure apparatus comprising: 2. A holding table (3) is mounted on a holding mechanism (8), said holding mechanism (8) is detachably supported by a coarse movement stage (4), and a fine movement stage (5) is mounted on said holding mechanism. 2. The exposure apparatus according to claim 1, wherein the fine movement stage is detachably supported by (8), and the fine movement stage is not affected by the operation of the coarse movement stage. 4.