JPH07104203B2 - Lighting optics - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an illumination optical apparatus, for example, in a semiconductor exposure apparatus, by providing an attenuating means, the light quantity of an illumination light flux having a large energy, the illuminance distribution, etc. can be easily obtained. It is designed to be measurable.

[Outline of Invention]

The present invention relates to an illumination optical device that illuminates an illumination target with an illumination light flux emitted from a light source, attenuates the light amount of the illumination light flux in the main optical path by the first transmissive reflecting member, and emits it to the external optical path. The emitted light flux is dimmed by the second transmissive / reflecting member to be returned from the external optical path to the main optical path, so that the light quantity of the illumination luminous flux is attenuated with a large dimming rate with a simple configuration. be able to.

[Conventional technology]

In a semiconductor exposure apparatus, when a wafer is exposed using a laser as a light source, the illuminance distribution of an illumination light flux irradiating the wafer and the exposure amount are measured so that the wafer can be finely exposed with the highest possible accuracy. Method is used to confirm that is appropriate.

Here, the light amount of the illumination light flux passing through the illumination main optical path from the light source to the wafer must have enough energy for exposing the wafer in practice, whereas the detector for measurement correctly performs the measurement operation. Since the energy of the measuring illumination luminous flux necessary for the measurement is remarkably small, it is necessary to provide a dimming device between the light source and the wafer to be illuminated in order to obtain an appropriate measuring illumination luminous flux. There is.

Conventionally, as this attenuator, the illumination light flux for exposure is transmitted through an attenuator such as an attenuator filter, a pinhole and an expander, and is limited by the attenuator to a size suitable for the sensitivity of the detector. A method of obtaining a so-called weak measuring illumination light flux having energy has been adopted.

[Problems to be solved by the invention]

However, in the semiconductor exposure apparatus, there is a tendency to increase the output of the light source in order to improve the throughput, and in addition to this, in order to make the line width of the pattern to be printed on the wafer to be exposed as small as possible, a short wavelength and high light source are used. A laser oscillator (for example, an excimer laser oscillator) capable of emitting an output laser beam has come to be used.

As a light attenuator for obtaining a weak measurement illumination light flux that is compatible with the sensitivity of the measurement detector from the exposure illumination light flux emitted from such a high-output light source, the dimming ratio is much higher than in the conventional case. In addition to making it large (for example, about 10 ^-7 to 10 ^-8 ), the illuminance distribution of the exposure illumination light flux,
It is necessary to obtain an illumination light flux for measurement that includes information such as the amount of light stably and with high accuracy.

However, the conventional dimming means have the following problems.

First, the neutral density filter has the possibility that, when light of short wavelength and high energy is incident, the incident light may exceed the heat resistance of the filter and cause performance deterioration or damage, thus obtaining stable neutral density characteristics. It is still inadequate in that it cannot do it.

Further, it is considered that if the diameter of the pinhole is reduced in principle, remarkably large dimming operation can be obtained, but in reality, there is a limit in reducing the diameter due to the processing of the pinhole. Further, although the pinhole is effective for detecting the illuminance distribution due to its structure, it has a drawback that it cannot be applied to the case where it is desired to collect the illumination light flux and measure the light quantity.

In addition to these means, it is conceivable to use an expander or the like that operates so as to reduce the light amount per unit area of the light beam incident on the measurement detector by multiplying the magnification, but as a practical use as a whole. Since it is inevitable that the configuration of (1) becomes considerably large, it cannot be applied to the use where a large amount of light reduction is required to about 10 ^-7 to 10 ^-8 as described above.

The present invention has been made in view of the above points, and an object of the present invention is to provide an illumination optical device having a simple structure that has a stable and large dimming action according to information to be measured.

[Means for solving problems]

In order to solve such a problem, the present invention has a light source means 2 for emitting a substantially parallel illumination luminous flux LB1 and a light quantity attenuating means 3, and the light quantity attenuating means 3 is incident with a predetermined transmittance or reflectance. The illumination light beam LB1 has a light source 2
Illumination flux LB
1st attenuation light flux (LB1 _a , LB
1 _g ) having a first transmissive / reflecting member (21A, 31A to 31B) that emits 1 _g ) from the main optical path to the external optical path, and an entrance surface and an exit surface having a predetermined transmittance or reflectance, A second attenuated light beam LB3, which is obtained by attenuating the light amount of the first attenuated light beams (LB1 _a , LB1 _g ) emitted from the transmissive / reflecting members (21A, 31A to 31B), is returned from the external optical path to the main optical path. The second transmissive / reflecting member (21B to 21D, 31C to 31D) which emits the light is provided.

[Action]

First and second transflective members (21A, 31A to 31B), (21B
~21D, 31C~31D), the illumination light flux amount only attenuate the first and second damping beams (LB1 corresponding to the incident surface and by the exit surface connexion determined transmittance or reflectance amount of LB1 _a, LB1 _g ),
Inject LB3.

Thus, in the main optical path, the first transmission / reflection member (21A, 31A
The first attenuated light flux (LB1 _a , LB1 _g ) emitted to the external optical path while being dimmed by the second transmission / reflection member (21B-21D, 31C-31D) is further reduced. It is illuminated and returned to the main optical path.

With such a simple configuration, it is possible to realize the illumination optical device having the attenuator 3 having a significantly large amount of light reduction.

〔Example〕

 An embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment] In FIG. 1, reference numeral 1 denotes an illumination optical device as a whole,
For example, an exposure illumination light beam LB1 formed of a laser light beam of a short wavelength and high energy emitted from a light source 2 formed of an excimer laser oscillator passes through the insertion / extraction position of the measurement attenuator 3 and then the half mirror 4 and the beam sequentially. The reticle 9 is illuminated via the shaping optical system 5, the fly-eye integrator 6, the condenser lens 7, and the reflection mirror 8. Then, a predetermined pattern on the reticle 9 is exposed and transferred onto the wafer 11 via the projection lens 10 by the illumination light beam LB2 that illuminates the wafer 11 to be exposed. Thus, from the light source 2 to the wafer 11
A main optical path for the exposure illumination light beam LB1 facing toward is formed.

As shown by the arrow a, the measurement attenuator 3 is detachably configured so that it can be inserted or pulled out between the light source 2 and the half mirror 4, and is measured when the wafer 11 is in the processing step (that is, the exposure mode). Attenuator 3 for exposure illumination light flux
The exposure illumination light flux LB1 can be directly incident on the half mirror 4 by being extracted from the main optical path of LB1.

As a result, an illumination light flux that is a high-energy laser light flux passes through the optical system from the half mirror 4 to the projection lens 10 based on the directly incident exposure illumination light flux LB1.
LB2 is shot.

On the other hand, in the measurement mode, the measurement attenuator 3 is inserted at the position shown in the figure, and thus the measurement illumination light beam LB3 obtained by attenuating the light amount of the exposure illumination light beam LB1 in the measurement attenuator 3 is a half mirror. 4 so that the light quantity of the measurement illumination light beam LB4 emitted from the optical system from the half mirror 4 to the projection lens 10 is reduced by an attenuation amount corresponding to the extinction ratio of the measurement attenuation unit 3. Has been done.

In this measurement mode, the irradiation measuring unit 15 shown by the broken line is arranged at the position of the wafer 11, and thus the light intensity is adjusted to the optimum amount for measuring the illuminance distribution or the irradiation amount on the wafer 11.

As the irradiation measuring unit 15, as shown in FIG. 2, a structure in which a pinhole plate SP is provided on the surface of an illuminance distribution measuring detector DT1 can be applied, and the measuring illumination further restricted by the pinhole. The illuminance distribution can be measured by the light flux LB4.

Further, as the irradiation measuring unit 15, as shown in FIG. 3, a unit having a detector DT2 for measuring the irradiation amount can be applied, whereby a measurement output representing the irradiation amount of the measuring illumination luminous flux LB4 is obtained. .

When in the exposure mode, part L of the illumination light flux for exposure LB1
B5 is extracted to the output energy measuring unit 16 in the half mirror 4, and the energy detecting light beam LB is output from the attenuating unit 17 thereof.
6 is obtained, and this energy detecting light beam LB6 is made incident on the output energy photodetector 18.

Thus, in the exposure mode, the output energy of the exposure illumination light beam LB1 output from the light source 2 is measured.

In the case of this embodiment, the beam shaping optical system 5 shapes the cross section of the laser beam emitted from the excimer laser oscillator used as the light source 2 into a rectangular shape, while shaping it into a square shape.

Thus, the illumination optical apparatus 1 in the exposure mode uses the exposure light beam LB2 irradiated from the projection lens 10 to the wafer 11 based on the exposure light beam LB1 for exposure having a short wavelength and a high output to form the exposure pattern formed on the reticle 9. The wafer 11 is exposed.

Then, the output energy of the light source 2 in the exposure mode is detected by the output energy photodetector 18 of the output energy measuring unit 16, and the normal operation of the light source 2 can be monitored based on the detection result.

The measurement attenuator 3 includes four transmission / reflection members 21A, 21B, 21.
It has C and 21D and a trap member 22.

The transmissive / reflecting members 21A to 21D are reflective transmissive / reflecting members 21 having the configuration shown in FIG. 4, and the incident surface of the parallel glass plate J1 is
A reflective coat with a predetermined low reflectance is used, or a coating with no low reflectance is used.The exit side surface of the glass plate has a reflectance that is sufficiently smaller than the reflectance of the incident side surface.
And the incident light beam LB11 is received at the incident surface of the parallel glass plate J1 at an incident angle of 45 °.

Under such a condition, the incident surface of the parallel glass plate J1 exhibits a very small reflectance, and therefore, most of the light rays of the incident light beam LB11 are transmitted into the parallel glass plate J1 and transmitted on the exit surface side. The trap light beam LB12 is emitted through the coat J2 without being substantially reflected.

Thus, a slight ray of light reflected on the incident surface of the parallel glass plate J1 is emitted as an outgoing attenuation luminous flux LB13 in a direction bent by 90 ° with respect to the incident luminous flux LB11.

In this way, the transflective members 21A to 21D are
As LB13, it is possible to obtain an emission attenuated light beam LB13 in which the energy of the incident light beam LB11 is attenuated with a markedly large extinction ratio.

The first transmitting / reflecting member 21A is provided in the main optical path when the exposure illumination light beam LB1 travels straight from the light source 2 to the half mirror 4 in the exposure mode. The attenuated light beam LB1 _a, which is bent toward one side and attenuated at a predetermined extinction rate, is made incident on the second transmissive reflection member 21B which constitutes an external optical path provided outside the main optical path.

The second transmissive / reflecting member 21B is disposed so that its entrance surface faces the first transmissive / reflecting member 21A, and thus the incident attenuated light beam LB1 _a is bent 90 ° and attenuated again at a predetermined extinction rate. The reduced luminous flux LB1 _b
Then, the light is emitted in a direction substantially parallel to the straight-ahead main optical path and is made incident on the third transmission / reflection member 21C.

The third transmissive / reflecting member 21C is disposed so that its entrance surface faces the second transmissive / reflecting member 21B, and thus the attenuated light flux L
The attenuated light beam LB1 _c, which is formed by bending B1 _b by 90 ° and attenuating again at a predetermined extinction rate, is incident on the fourth transmissive reflecting member 21D.

The fourth transmitting / reflecting member 21D is arranged such that the incident surface thereof faces the third transmitting / reflecting member 21C in the straight main optical path through which the exposure illumination light beam LB1 passes in the exposure mode, whereby the attenuated light beam LB1 _c is reduced to 60%. The attenuated light flux, which is bent and attenuated at a predetermined extinction rate, is sent out as the measurement illumination light flux LB3 of the measurement attenuation unit 3 in a direction that matches the straight traveling direction of the exposure illumination light flux LB1.

The measurement illumination luminous flux LB3 emitted from the measurement attenuator 3 is
The light is emitted from the projection lens 10 through the optical system from the half mirror 4 to the projection lens 10, and is thus irradiated onto the irradiation measurement unit 15 as a measurement illumination light beam LB4.

In this way, in the measurement mode, the transmissive / reflecting members 21A, 21B, 21C, 21D as the four-stage attenuating means are inserted in the straight main optical path from the light source 2 of the exposure illumination light beam LB1 to the half mirror 4. , It is possible to obtain the measurement illumination light flux LB3 in which the light amount of the exposure illumination light flux LB1 is substantially attenuated practically, and by this, the illuminance distribution measurement detector DT1 (FIG. 2) provided in the irradiation measurement unit 15 is obtained. Or detector DT2 for dose measurement
Since a highly sensitive detector capable of detecting a minute amount of light can be used as (FIG. 3), the illuminance distribution and the irradiation amount can be measured with high accuracy.

For this reason, the optical system through which the exposure illumination light flux LB1 in the exposure mode passes is used as it is as the optical path from the half mirror 4 to the irradiation measuring unit 15, so that the irradiation measuring unit 15
Illuminance distribution of the measuring illumination light flux LB4 incident on
The irradiation amount has information corresponding to the illuminance distribution and the irradiation amount of the illumination light beam LB2 irradiated onto the wafer 11 based on the exposure illumination light beam LB1 in the exposure mode.

Thus, according to the embodiment shown in FIG. 1, it is possible to reliably obtain the measurement illumination light flux LB4 representing the optical information of the illumination light flux LB2 in the exposure mode by using the photodetector with high accuracy.

In the case of this embodiment, the trap member 22 is composed of a light shielding plate,
When the exposure illumination light beam LB1 having high energy is incident on the first transmissive reflection member 21A, the trap light beam LB12 (FIG. 4) that transmits the light beam is transmitted and reflected on the emission side.
Shield the light to prevent it from entering 21D (Fig. 1).

As a result, it is possible to prevent the measurement operation from being adversely affected by unnecessary light.

Incidentally, when the exposure illumination light beam LB1 having a large energy enters the first transflective member 21A, most of the light beam passes through the transflective member 21A and is emitted as the trap light beam LB12 (fourth). Figure), the first transflective member 21A
The energy of the laser light flux that is going to go straight from the fourth transmission / reflection member 21D has an extremely large value. Therefore, if this is directly incident on the fourth transmitting / reflecting member 21D, an excessive amount of light is emitted to the measuring detector as the measuring illumination luminous flux LB4 emitted from the projection lens 10, but measurement cannot be performed, but it is blocked. This problem can be easily solved by the trap member 22 acting as a plate.

In the case of the embodiment shown in FIG. 1, the attenuator 17 of the output energy measuring unit 16 has a pair of transflective members 25A and 25B.

As shown in FIG. 5, the transflective members 25A and 25B have a parallel glass plate J11, a highly reflective coat J12 having a high reflectance is attached to the incident surface of the parallel glass plate J11, and the exit surface is practically reflected. The transmission type transmissive / reflecting member 25 has a structure to which a transmissive coat J13 is attached so as not to cause

Thus, when the incident light beam LB21 is incident on the parallel glass plate J11 at an incident angle of 45 °, most of the light beam is reflected by the high reflection coat J12 and emitted as a trap light beam LB22 in the direction bent at 90 °. It

On the other hand, the light left unreflected by the high-reflection coat J12 passes through the parallel glass plate J11 and is substantially not reflected by the transmission coat J13 on the exit surface, and the light flux L is emitted.
It is ejected as B23. As a result, the outgoing light beam LB23 formed by attenuating the incident light beam LB21 with a predetermined extinction ratio is transmitted and reflected by the transmission / reflection member 25.
Will be obtained from

Thus, when the laser beam LB5 reflected and taken out by the half mirror 4 (FIG. 1) is incident on the first transmissive reflection member 25A, it is attenuated by the extinction rate of the first transmissive reflection member 25A. The attenuated luminous flux LB5 _{a that} has been generated is the second transmission / reflection member.
It is incident on 25B.

The second transmissive reflecting member 25B, at the time of transmitting the attenuated light beam LB5 _a incident in the same manner, the output energy photodetector attenuation light beam is attenuated again by a predetermined extinction ratio as an energy detecting light beam LB6 18 Inject.

In this case, the trap light beam LB22 (FIG. 5) reflected by the first transmitting / reflecting member 25A is absorbed by the trap member 26 and thus does not adversely affect other optical systems.

According to the output energy measuring unit 16 of the configuration shown in FIG. 1, the main beam path of the exposure illumination light beam LB1 toward the optical system from the light source 2 to the projection lens 10 is changed to a laser light beam LB5 separated by the half mirror 4. Based on this, the light amount can be reduced to a light amount suitable for the sensitivity of the output energy photodetector 18 by reducing the light amount when passing through the transmissive transmission / reflection members 25A and 25B, and thus in the exposure mode. The output energy of the light source 2 can be reliably monitored.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention. As shown by affixing the same reference numerals to portions corresponding to those in FIG. Two pairs of transflective members 31A, 31B, and 31C, 3 using the transmissive transmissive reflective member 25 described above with reference to FIG.
1D, these transflective members 31A, 31B, and 31C, 3
1D is arranged in that order on the straight main optical path from the light source 2 of the exposure illumination light beam LB1 to the half mirror 4.

That is, the first transmissive / reflecting member 31A receives the exposure illumination light beam LB1 emitted from the light source 2 at an incident angle of ₊ 45 ° and attenuates the light beam LB1 _f with a predetermined extinction ratio to produce a second transmissive / reflecting member. It is incident on 31B.

The second transmissive / reflecting member 31B receives the attenuated light beam LB1 _f at an incident angle of −45 °, and re-attenuates the attenuated light beam LB1 _g at a predetermined extinction ratio to enter the third transmissive / reflecting member 31C.

The third transmissive reflective member 31C is incident attenuation beam LB1 _g +45 ° angle of incidence undergoes attenuation optical beam LB1 which is attenuated again by a predetermined dimming rate _h to a fourth transmissive reflecting member 31D.

The fourth transmissive / reflecting member 31D outputs the attenuated luminous flux LB1 _h by −4
The light is received at an incident angle of 5 ° and attenuated again with a predetermined extinction ratio, and the attenuated light flux is emitted from the measurement attenuating unit 3 to the half mirror 4 as a measurement illumination light flux LB3.

In this case, the trap light beam LB1 _j reflected by the first transflective member 31A is absorbed by the trap member 32.

According to the configuration of FIG. 6, the transmissive transmission / reflection member 25 (the fifth type
(Fig.) Is used to measure the light quantity of the exposure illumination light beam LB1
The value can be surely attenuated to a value commensurate with the detection sensitivity of the detector, and by doing so, the illuminance distribution and the irradiation amount can be measured using the detection element with high accuracy.

In addition to this, according to the configuration of FIG. 6, the transmissive / reflecting members 31A, 31B, and 31C, 31D are arranged so that the incident angles thereof are sequentially and alternately changed. In 31A and 31C, even if the outgoing light beam shifts in one direction with respect to the incident light beam and shifts from the main optical path to the external optical path,
It is possible to attenuate the light amount of the light flux at a predetermined extinction ratio while pulling it back to the main optical path by the next transmission / reflection members 31B and 31D.

Together with this, a pair of transflective members 31A, 31B, and 31C, 3
By combining 1D, the optical characteristics of each transflective member can be complementarily compensated, and the measurement attenuator 3 is inserted as the measurement illumination light beam LB4 obtained from the projection lens 10. Because of this, the luminous flux
It is possible to suppress the change in the optical characteristics that occurs in LB2 to a sufficiently small value for practical use.

[Third Embodiment] FIG. 7 shows a third embodiment of the present invention. Instead of the measuring attenuator 3 of FIG. 1 or 6, the configuration of FIG. 7 can be applied. .

That is, the exposure illumination light beam LB1 emitted from the light source 2 (FIG. 1 or FIG. 6) is incident through the incident light coupling section 35, and the exposure illumination light beam LB1 is sequentially passed through the reflection mirrors 36 and 37 to determine the illuminance. Attenuator 38 for distribution measurement or attenuator 39 for dose monitoring
Through the exit light coupling section 40
Inject LB3.

Here, the illuminance distribution measurement attenuator 38 and the dose monitoring attenuator 39 can be inserted or pulled out in the directions of arrows j and k with respect to the main optical path, respectively. Part 38 and attenuation part for dose monitor
When 39 is simultaneously moved in the pull-out direction, the exposure illumination light beam LB1 reflected by the reflection mirror 37 goes straight and is not attenuated from the emission light coupling portion 40 to the half mirror 4 (FIG. 1 or 6). It is designed to be able to eject.

In the case of this embodiment, the illuminance distribution measurement attenuating section 38 comprises two pairs of transmissive / reflecting members 38 each composed of a transmissive transmissive / reflecting member 25 (Fig. 5) in the same manner as described above with reference to Fig. 6.
It has a configuration in which A, 38B, and 38C, 38D are arranged on the straight optical path.

On the other hand, the dose monitor attenuator 39 sequentially changes the six transmission / reflection members 39A, 39B, 39C, 39D, 39E, 39F, which are the reflection type transmission / reflection members 21 described above with reference to FIG. On the other hand, it is configured so as to obtain an outgoing light flux that is bent by 90 °.

In the configuration shown in FIG.
In the case of measuring the illuminance distribution shown in FIG. 1, the illuminance distribution measuring attenuator 38 is inserted in the straight main optical path from the reflection mirror 37 to the outgoing light coupling unit 40.

At this time, the illuminance distribution measurement attenuator 38 attenuates the exposure illumination light flux LB1 reflected by the reflection mirror 37 by the four transmissive transmissive / reflecting members 38A to 38D to obtain the measurement illumination light flux LB3. The light is emitted to the emitted light coupling section 40.

At this time, the emission amount attenuating unit 39 maintains the extracted state, and thus the measurement illumination light beam LB3 emitted from the illuminance distribution measuring attenuating unit 38 is emitted from the emission light combining unit 40 to the half mirror 4 (FIG. 1). And is supplied to the optical system of the subsequent stage. Further, an illuminance distribution measuring detector DT1 (FIG. 2) is inserted at the position of the wafer 11 as the irradiation measuring unit 15, and thus the illuminance distribution is detected.

Further, when measuring the irradiation amount, the irradiation amount attenuating unit 39 is inserted in the straight main optical path from the reflection mirror 37 to the emission light coupling unit 40, and thus the exposure illumination light flux LB1 reflected by the reflection mirror 37 is obtained. Six-stage reflective type transmissive reflective members 39A to 39
The light amount is attenuated by being sequentially reflected between F and is emitted to the emission light coupling portion 40 as the measurement illumination light beam LB3.

At this time, since the illuminance distribution measurement attenuator 38 is pulled out to the retracted position, the exposure illumination light flux LB1 reflected by the reflection mirror 37 is not attenuated but is transmitted by the irradiation amount monitor attenuator 39 through the first transmission. It is directly incident on the reflecting member 39A.

When it is necessary to further increase the attenuation rate when measuring the irradiation amount, it is effective to insert the illuminance distribution measuring attenuation section 38 in the optical path.

Also in the case of this embodiment, the illuminance distribution measurement attenuation unit 38
The trap light beam LB1 _n of the first transmission / reflection member 38A is absorbed by the trap member 41 made of an absorbing material, and the first transmission / reflection member of the dose monitor attenuation unit 39 is used.
The trap light beam LB1 _{k of} 39A is absorbed by the trap member 42 which is also made of an absorbing material.

With the configuration shown in FIG. 7, the same effects as those described above with reference to FIGS. 1 and 6 can be obtained.

Thus, if all the transmissive members constituting the illuminance distribution measurement attenuating section 38 are of the transmissive type as in the above-described configuration, the transmissive type of the optical system is more advantageous than the reflective type. The difference in the optical path length of the optical system between the exposure mode and the measurement mode, which occurs when the optical path is inserted into the main optical path, can be minimized, and the illuminance distribution on the wafer caused by the fluctuation of the optical path length caused by the insertion of the attenuator Change can be minimized. Therefore, the illuminance distribution on the wafer in the exposure mode can be more uniformly attenuated at a predetermined attenuation rate, and the illuminance distribution can be measured with high accuracy.

[Other Examples]

(1) Instead of the trap member 22 of the measurement damping unit 3 shown in FIG. 1, the structure shown in FIG. 8 can be applied.

In FIG. 8, the trap member 22 has a structure in which a light absorbing member having a predetermined thickness is shaped into a “” shape in cross section, and the trap light beam LB1 _e transmitted through the first transmissive reflecting member 21A is opened through the opening 22A.
Introduced from the inside. Thus, the trap light beam LB1 _e introduced into the trap member 22 is rapidly absorbed by the trap member 22 while reflecting between the walls made of the light absorbing member.

Thus, according to the configuration of FIG. 8, the trap light beam LB1 from the first transmissive / reflecting member 21A whose energy is still sufficiently large.
By reliably absorbing _e , it is possible to prevent adverse effects such as flare on the optical system.

Similarly, as the trap member 32 of the measuring attenuator 3 of FIG. 6, an absorption member having an internal space having a “V” cross section as shown in FIG.
It can be configured to absorb _j .

(2) In the above-mentioned embodiment, the case where the parallel glass plate is used as the transmissive / reflecting member has been described, but even if a prism is used instead of this, the same effect as in the above case can be obtained.

(3) In FIG. 1, the measurement attenuating unit 3 uses four reflective transmissive reflective members 21A to 21D, but the number of reflective transmissive reflective members is not limited to this. The exposure illumination light flux reflected to the outside with respect to the main optical path may be returned to the main optical path, and three or more reflective type transmissive / reflecting members may be used.

(4) In the embodiment of FIG. 6 in which a transmissive type is used as the transflective member, when the transmissive reflective members 31A to 31D have polarization characteristics, the first and second transmissive reflective members 31A and 31B are used. If the second set consisting of the third and fourth transmissive / reflecting members 31C and 31D is provided at a position rotated by 90 ° about the optical axis with respect to the first set consisting of By being able to complementarily compensate the polarization characteristics of the second and second sets, the influence of the polarization characteristics of each of the transflective members 31A to 31D can be further reduced.

(5) In the above-described embodiments, the case where the measurement attenuator 3 is configured to attenuate the light amount of the illumination light flux by using only the reflective transmissive reflective member or only the transmissive transmissive reflective member has been described. However, the light amount of the illumination light flux may be attenuated by combining reflective and transmissive transmissive reflective members as necessary.

(6) In the above-described embodiments, the present invention is applied to the case of measuring the illuminance distribution and the irradiation amount on the wafer in the semiconductor exposure apparatus, but the present invention is not limited to this, and the point is that the light amount of the illumination luminous flux is remarkably increased. It can be widely applied when it is necessary to attenuate it dynamically.

(7) In the embodiment shown in FIG. 1, an embodiment in which the present invention is applied to an optical system configured such that the exposure illumination light beam LB1 travels straight as the main optical path from the light source 2 to the half mirror 4 has been described. Instead of this, as shown in FIG.
When the exposure illumination light beam LB1 emitted from is reflected by the reflection mirror 41 so as to be bent at 90 ° and is incident on the half mirror 4,
As the measurement attenuator 3, three transmission / reflection members 42A, 42B,
42C should be used.

Here, the transmissive / reflecting members 42A, 42B, and 42C are configured by the reflective transmissive / reflecting members described above with reference to FIG. 4, and in the measurement mode, the first transmissive / reflecting member 42A is inserted on the incident side of the reflective mirror 41. Therefore, the light is incident on the second transmissive / reflecting member 42B by being bent and reflected by 90 ° outwardly, is bent and reflected again by 90 ° on the second transmissive / reflecting member 42B, and is inserted into the exit-side main optical path of the reflecting mirror 41. A third transmissive reflection member
By making the light incident on 42C, the measurement illumination light beam LB3 is transmitted to the half mirror 4 through the main optical path.

According to the configuration of FIG. 10, the three-stage transflective members 42A, 42B,
42C makes it possible to obtain a measurement illumination light flux LB3 in which the light amount of the exposure illumination light flux LB1 is attenuated at a predetermined extinction rate.

(8) In the above-described embodiment, the trap member is provided only in the first transmissive / reflecting member that receives the incident illumination light beam among the transmissive / reflective members included in the measurement attenuating unit 3, but the present invention is not limited to this. Alternatively, trap members may be provided for other transmissive / reflecting members.

〔The invention's effect〕

As described above, according to the present invention, by combining the first transmissive / reflecting member that extracts the illumination light flux outward from the main optical path and the second transmissive / reflecting member that returns the extracted illumination light to the main optical path. Since the measurement attenuator is configured as described above, the illumination light can be reliably attenuated in the measurement mode with a simple configuration in which the measurement attenuator can be inserted into or pulled out from the main optical path. A possible illumination light optical device can be easily realized.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of an illumination optical device according to the present invention, FIGS. 2 and 3 are schematic diagrams showing a detailed configuration of an irradiation measuring unit 15, and FIGS. 4 and 5 are reflection type and A schematic diagram showing the detailed structure of a transmissive transmission / reflection member, FIGS. 6 and 7 are system diagrams showing second and third embodiments of the present invention, and FIGS.
FIG. 10 is a system diagram showing another embodiment of the measuring attenuator. 1 ... Illumination optical device, 2 ... Light source, 3 ... Measurement attenuator, 4 ... Half mirror, 5 ... Beam shaping optical system, 6
...... Fly eye integrator, 7 …… Condenser lens, 8 …… Reflecting mirror, 9 …… Reticle, 10 …… Projection lens, 11 …… Wafer, 16 …… Output energy measuring unit, 21
A-21D, 25A-25B, 31A-31D, 38A-38D, 39A-39F, 42
A to 42C ... Transparent / reflective member.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/027

Claims (1)

[Claims] 1. A light source means for emitting substantially parallel illuminating light flux, and a light quantity attenuating means, the light quantity attenuating means having an incident surface and an exit surface having a predetermined transmittance or reflectance, and the illuminating light flux. A first transmitting / reflecting member for emitting a first attenuated light flux, which is inserted into the main optical path from the light source toward the illumination target and attenuates the light quantity of the illumination light flux, to the external optical path from the main optical path; A second attenuated light flux having an incident surface and an emission surface with a transmittance or a reflectance and attenuating the light amount of the first attenuated light flux emitted from the first transmissive reflection member in the external optical path is described above. A second transmissive / reflecting member that emits light so as to return from the external optical path to the main optical path.