JPH0396494A - Exposure device - Google Patents

Abstract

PURPOSE:To avoide deterioration in the measurement accuracy of a jogging stage position by providing the exposure device stage wherein a coarse stage operates on a jogging stage, and this jogging stage does not influence the opera tion of the coarse stage. CONSTITUTION:The position of a coarse stage 4 relative to a jogging stage 5 is measured with a coarse stage end measuring machine 41 comprising a magnetic linear sale on the jogging stage 5. On the other hand, the shift amount of the jogging stage 5 is measured with an end measuring system 6 constituted with a mirror 61 fixed on the jogging stage 5, an interferometer 62 and a protec tive tube 63 covering a laser beam passage 64 between the mirror 61 and the interferometer 62. As the shift stroke of the jogging stage 5 is very fine, how ever, a fixed length tube of high rigidity metal is used for the protective tube 63, thereby enabling the nearly complete enclosure of the laser beam passage 64. According to the aforesaid construction, the laser beam passage 64 becomes free from an influence due to the fluctuation of the atmosphere, and the accu racy of a laser end measurement system 6 can be fully obtained.

Description

[Detailed Description of the Invention] [Summary] Regarding the stage for an exposure device, the length of the protective tube constituting the laser length measurement system is set to a fixed length so that the influence of the operation of the coarse movement stage does not affect the fine movement stage. A holding table on which an object to be exposed is attracted, a coarse movement stage, a fine movement stage, a coarse movement stage length measuring device for measuring the position of the coarse movement stage, and a coarse movement stage length measuring device fixed to the fine movement stage. An exposure apparatus having a laser length measuring system for measuring the position of a fine movement stage, which comprises a mirror, an interferometer, and a protective tube whose ends are in contact with the mirror and the interferometer, respectively. is placed on a coarse movement stage, the coarse movement stage is placed on a fine movement stage via a support mechanism,
The exposure apparatus is configured such that the coarse movement stage operates on a fine movement stage, and the fine movement stage has an exposure apparatus stage that is not affected by the operation of the coarse movement stage.

[Industrial application field]

The present invention relates to a stage for an exposure apparatus, and particularly to a stage structure that allows highly accurate length measurement using a laser interferometric length measuring device without being affected by atmospheric fluctuations.

In recent years, with the miniaturization and higher integration of electronic devices, mainly semiconductor integrated circuits, the miniaturization of patterns has become smaller, for example.
．． It has entered the submicron region of 5 μm.

In line with this trend, development of various microfabrication techniques for defining the shape of micropatterns is being actively carried out in various places.

Among various zero-force techniques for performing fine patterning, the vacuuming technique centered on photoetching, generally called photolithography, is currently the most utilized.

This photo-etching patterning technique 4i! One of the elemental technologies in this is exposure technology.

Depending on the type of light source (ray source), exposure technology may include ultraviolet exposure, which has traditionally been the most common method used for transfer, or X-ray exposure using X-cotton as a light source, which is expected to become more popular in the future.
Since it is a charged 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, which is used not only for transfer but also for direct writing, and ion beam exposure using an ion beam as a light source.

However, whichever exposure method is used, highly accurate positional control of the stage that supports and moves the exposed object, such as a wafer or mask, is essential, and highly accurate control of 0.005 μm or less is required. ing.

[Conventional technology]

A stage capable of highly accurate position control with one IQ has a structure that combines a phase motion stage and a fine motion stage.

The coarse movement stage is mechanically driven, whereas the fine movement stage uses, for example, a piezoelectric actuator that utilizes electromechanical conversion of a piezoelectric material.

Further, to measure the amount of movement, for example, a magnetic linear scale is used for the coarse movement stage, and a laser length measurement system is generally used for the fine movement stage.

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

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

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

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

On the other hand, a mirror 61 is attached to the fine movement stage 5, and the length of the fine movement is measured by the laser length measuring system 6 with reference to the mirror 61.

As the laser length measuring system 6, a dual frequency laser interferometric length measuring device is widely used.

A dual-frequency laser interferometer uses two laser beams with different wavelengths emitted from a dual-wavelength Zeeman laser, which are first separated by a beam splitter into a reference beam and a length-measuring beam.

The length measurement light is further divided into two parts by a deflection beam splitter: a reference light that passes through a position reference retroreflector, and a reference light that passes through a moving position measurement retroreflector and then passes through a moving retroreflector for position measurement. This results in shifted length measurement light.

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

By the way, it is known that when this dual-frequency laser interferometric length measuring device is used in the atmosphere, the measured value is affected by the temperature, atmospheric pressure, humidity, etc. of the atmosphere. This is due to the fact that the refractive index of the atmosphere changes depending on these environmental parameters.

In order to reduce the influence of these environmental parameters, the entire length measurement system is placed in a constant temperature bath to stabilize the environment. Alternatively, on the assumption that the environmental parameters are homogeneous in the vicinity of the length measuring section, they are measured by appropriate means, and the length measurement values are corrected using a mathematical formula given theoretically.

However, for the length being measured, for example, 10-“
If the following high accuracy is to be achieved, the atmosphere in the path 64 of the laser beam cannot be homogeneous, so the influence of subtle fluctuations in the atmosphere on the measured length value becomes a problem.

As an example, approximately 200
It is experimentally known that the reproducibility of measured values when a fixed distance of mm is continuously measured is 0.1 μm or less, which is a poor result. The resolution of the laser interferometer itself is 0.
Since the thickness of about 0.025 μm is being manufactured, this can be said to be a serious problem.

Therefore, conventionally, attempts have been made to cover the path 64 of the laser beam for length measurement with a protective tube 63 to make it less susceptible to the influence of the atmosphere.

[Problem to be solved by the invention]

As described above, although the length measurement accuracy of the laser interferometric length measuring device itself is very high, fluctuations in the atmosphere, which is the path of the laser beam for length measurement, affect the length measurement value. Therefore, in order to prevent this influence, the path of the laser beam is covered with a cylindrical member.

However, in the conventional stage structure, since the fine movement stage also moves in conjunction with the movement of the coarse movement stage, the position of the mirror provided on the fine movement stage for laser length measurement changes significantly.

Therefore, a cylindrical member is required that has a large stroke in the longitudinal direction and high rigidity in a direction perpendicular to this.

However, it has been a difficult problem to realize such a cylindrical member.

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

Then, the fluctuation in the length of the laser beam path for length measurement of the laser length measurement system used to measure the position of the fine movement stage is shortened, and the length of the cylindrical member covering the path is fixed to prevent atmospheric moisture. The aim is to provide a new stage structure that can avoid the effects of

[Solve the problem. means to decide]

The above-mentioned problems include: a holding table on which the object to be exposed is attracted; a coarse movement stage; a fine movement stage; a coarse movement stage length measuring device for measuring the position of the coarse movement stage; an exposure apparatus comprising: a mirror; an interferometer; and a laser length measurement system for measuring the position of a fine movement stage, which comprises a protective tube whose ends are in contact with the mirror and the interferometer, respectively, the holding device comprising: a base is placed on a coarse movement stage, the coarse movement stage is placed 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 moved on the coarse movement stage. An exposure apparatus configured to have an exposure apparatus stage that is not affected by the operation, or a holding table is placed on a holding mechanism, the holding mechanism is removably supported on a coarse movement stage, and the fine movement stage is a holding mechanism. The present invention is solved by an exposure apparatus configured to have an exposure apparatus stage which is detachably supported by the fine movement stage and which is not affected by the operation of the coarse movement stage.

[For production]

As mentioned above, in conventional stages for exposure equipment, the fine movement stage is also moved greatly in conjunction with the large movement of the coarse movement stage, so the length of the protective tube that makes up the laser length measurement system is However, unless the length is variable, the path of the laser beam cannot be sufficiently covered. Moreover, it was extremely troublesome to make a protective tube of variable length. In contrast, in the present invention, the path of the laser beam can be sufficiently covered even by using a protective tube having a fixed length.

In other words, in a laser length measurement system, a laser beam emitted from an interferometer reciprocates inside a protective tube and is reflected on a mirror provided on a fine movement stage to measure length.
The operating range of this fine movement stage itself is, for example, at most 100
Since it is on the order of μm, the operating range of the coarse moving stage extends to the fine moving stage and is stacked on top of the operating range of the fine moving stage to prevent the operating range of the fine moving stage from increasing.

One means for realizing such an operational relationship between the coarse movement stage and the fine movement stage is to place a fine movement stage on top of the coarse movement stage, and to place a holder on top of the fine movement stage, which attracts the object to be exposed. Instead of a conventional stage for exposure equipment that is placed and positioned, first, a coarse movement stage is operated, and the exposed object is moved with an accuracy of about 0.5 μm using a magnetic linear scale, for example, independently of the fine movement stage. I'm trying to roughly position it.

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

In this way, the operation of the coarse movement stage will not affect the fine movement stage at all, so the length of the protective tube that makes up the laser length measurement system can be determined by considering only the original operating range of the fine movement stage itself. Often, this means that even if the length of the protective tube is substantially fixed, it is possible to sufficiently cover the path of the laser beam.

In another implementation means, a holding base that attracts the exposed object is placed on a holding mechanism that is removably placed on the coarse movement stage, and on the other hand, this holding mechanism holds the fine movement stage. It is designed to be removably supported.

First, with the holding stand in contact with the holding mechanism and the fine movement stage removed, the coarse movement stage is operated, and the object to be exposed is roughly positioned via the holding mechanism independently of the fine movement stage. That's what I do. Next, the coarse movement stage and the holding mechanism are released from contact, and the holding mechanism and the fine movement stage are brought into contact with each other, and the position of the exposed object held by the holding mechanism is finely adjusted by the fine movement stage. There is.

In this way, large movements due to coarse movement stage operation will be
Since it does not affect the fine movement stage in any way, the length of the cylinder 8i can be set to a fixed length, and as a result, it becomes possible to sufficiently cover the path of the laser beam.

By the way, according to the exposure apparatus of the present invention, the absolute positional accuracy of an exposed object such as a wafer with respect to, for example, an interferometer is restricted by the positional accuracy of the coarse movement stage.

By the way, in exposure equipment, especially in equipment that transfers mask patterns such as X-ray exposure equipment, it is necessary to precisely align the marks on the mask and the marks on the wafer, and to avoid fluctuations in the position of the wafer with respect to the mask. shaking)
is required to be made smaller.

In response to this requirement, the absolute positional accuracy of the exposed object positioned by the coarse movement stage is, for example, within the mark capture range of the alignment device (positioning device). It is sufficient that the mark shown in is included.

Therefore, the above-mentioned absolute positional accuracy of the coarse movement stage is sufficiently accurate.

(Example) FIG. 1 is an explanatory diagram of one embodiment of the present invention, and FIG. 2 is an explanatory diagram of another embodiment of the present invention.
The figure (B) shows the state during fine movement.

Example: l In FIG. 1, a coarse movement stage 4 is placed on a fine movement stage 5 via a support mechanism 7. This support mechanism 7 includes coarse movement means consisting of an air slide and a near motor;
The holding means consists of a vacuum suction pad. A holding table 3 made of a vacuum suction pad is provided on the support mechanism 7, so that the object 2 to be exposed, such as a wafer, can be suctioned and 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 consisting of a magnetic linear scale provided on the fine movement stage 5. It is connected to the servo operation system.

Further, the fine movement stage 5 has a movement stroke of approximately 100μ.
It is made to move slightly by a piezoelectric actuator.

On the other hand, the amount of movement of the fine movement stage 5 is determined by a mirror 61 fixed on the fine movement stage 5, an interferometer 62, and a protective tube 63 that covers a laser beam path 64 connecting the mirror 61 and the interferometer 62. This is carried out using a laser length measuring system 6. This laser length measurement system 6 is connected to a servo operation system for fine movement (not shown).

However, since the movement stroke of the fine movement stage 5 is extremely small, it was possible to completely cover the laser beam path 64 by using a highly rigid metal tube with a fixed length attached to the protective tube 63. .

As a result, it was confirmed that by preventing the influence of atmospheric fluctuations on the laser beam path 64, the accuracy of the laser length measurement system 6 could be fully brought out.

Embodiment 2 In FIG. 2(A), the coarse movement stage 4 is placed on a coarse movement part guide 42 and can be moved by an air slide and a near motor (not shown). A holding mechanism 8 is removably supported on the coarse movement stage 4 via a sliding arm 43 by vacuum suction.

Further, on this holding mechanism 8, a holding table 3 made of a vacuum suction pad is provided, and the object to be exposed, such as a wafer, is held.
It is designed to be able to absorb and hold.

On the other hand, a donut-shaped fine movement stage 5 is placed on a donut-shaped fine movement portion guide 51 from which the coarse movement arm 43 can escape, and is movable by fine movement means consisting of a piezoelectric actuator (not shown). It has become. The fine movement stage 5 and the holding mechanism 8 can be detachably supported by vacuum suction.

The coarse movement stage 4 is positioned above the coarse movement section guide 42 so that its length can be measured by a coarse movement stage length measurement 2W41 consisting of a magnetic linear scale.

Further, the fine movement stage 5 has a movement stroke of approximately 100μ.
It is made to move slightly by a piezoelectric actuator.

Furthermore, the amount of movement of the fine movement stage 5 is determined by a laser length measuring system 6 having the same structure as in the first embodiment.

The coarse movement operation is performed by lifting the holding mechanism 8 by the coarse movement arm 43 and separating it from the fine movement stage 5, and moving the coarse movement stage 4 until the holding mechanism 8 is coupled to the coarse movement arm 43. ing.

Next, in the same figure (B), the fine movement operation is performed by moving the fine movement stage 5 while 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. It has become.

In this fine movement operation, the movement stroke of the fine movement stage 5 is very small, so a metal cylinder with high rigidity and fixed length is used as the protection cylinder 63 to completely guide the laser beam path 64. I was able to cover it.

As a result, similarly to the first embodiment, the path 64 of the laser beam
It was confirmed that it was possible to prevent the effects of atmospheric fluctuations and fully bring out the accuracy of the laser length measurement system 6.

In this β, the movement means of the coarse movement stage and fine movement stage are
Although coarse movement means consisting of an air slide and near motor and fine movement means consisting of a piezoelectric actuator were used, various modifications can be made to these drive means.

In addition, the effects of the present invention can be achieved precisely because a laser length measurement system is used to measure the position of the fine movement stage, but in addition to a flat mirror, various retroreflectors (reverse movement reflector) can be used.

Furthermore, for length measurement of the position of the phased stage, various modifications are possible in addition to the magnetic linear scale such as Magnescale (trademark).

〔Effect of the invention〕

As described above, according to the exposure apparatus of the present invention, when the object to be exposed is moved roughly and greatly by the coarse movement stage, the operation of the coarse movement stage has no effect on the fine movement stage. You can do it like this. Therefore, since the movement range of the coarse movement stage is not added to the movement range of the fine movement stage, it is possible to suppress the movement range to about 100 μm, which is the original movement range of the fine movement stage itself.

Therefore, in a laser length measurement system used for position measurement of a fine movement stage, a rigid cylinder with a fixed length can be used as a protective cylinder that covers the path of the laser beam. This makes it possible to stably cover the entire length of the laser beam path.

As a result, it is possible to avoid deterioration in the measurement accuracy of the position of the fine movement stage due to the influence of atmospheric fluctuations on the laser beam. It greatly contributes to development.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of another embodiment of the present invention, and FIG. 3 is a structural diagram of a conventional stage. In the figure, l is the exposure device stage, 2 is the object to be exposed, 3 is the holding table, 4 is the coarse movement stage, 4l is the coarse movement stage length measurer, 42 is the coarse movement part guide, 43 is the coarse movement arm, 5 is the fine movement stage, 5
1 a fine movement section guide; 6 a laser length measurement system; 61 a mirror 62 an interferometer; 63 a protection tube; 64 a laser beam path; 7 a support mechanism; and 8 a holding mechanism. An explanatory diagram of an example of a wooden sentinel. Figure 1. 1)

Claims (1)

[Claims] 1) Position measurement of a holding table (3) on which the object to be exposed (2) is attracted, a coarse movement stage (4), a fine movement stage (5), and the coarse movement stage (4). a coarse movement stage length measurer (41), a mirror (61) fixed to the fine movement stage (5), an interferometer (62), and a mirror (61) and the interferometer (2).
) and a protective tube (63) whose ends are in contact with the laser length measuring system (63) for position measurement of the fine movement stage (5).
), wherein the holding table (3) is placed on the coarse movement stage (4), and the coarse movement stage (4) is connected to the fine movement stage (4) via a support mechanism (7). 5), the coarse movement stage (4) operates on the fine movement stage (5), and the fine movement stage (5) operates on the coarse movement stage (5).
An exposure apparatus characterized by having an exposure apparatus stage (1) that is not affected by the operation of item 4). 2) The holding table (3) is placed on the holding mechanism (8), the holding mechanism (8) is removably supported by the coarse movement stage (4), and the fine movement stage (5) is mounted on the holding mechanism (8). The exposure apparatus according to claim 1, wherein the exposure apparatus is detachably supported by the fine movement stage (5), and the fine movement stage (5) is not affected by the operation of the coarse movement stage (4).