JPH06118338A - Optical device - Google Patents

Abstract

PURPOSE:To simply provide an optical device of high accuracy at low cost by providing plural reflecting areas having each different spectral reflection factor characteristic on the same surface as for the reflecting surface of an optical path bending member. CONSTITUTION:When an excimer light illuminates an observation object surface 10 through a reducing projection lens, etc., light having optical information of an alignment mark and a focus detection mark arranged on the object surface 10 is photodetected by a CCD camera 9 through an objective lens barrel 6, an optical path bending member 7-1, a relay lens barrel 8, and optical path bending members 7-2, 7-3. Subsequently, by a signal from the CCD camera 9, position information and focus information of the object surface 10 is calculated by an arithmetic controller, and positioning of the object surface 10 and other control are executed. Also, a monitor system monitors a fluctuation of an optical axis usually or in accordance with necessity, and in the case abnormality is generated, a warning signal is generated by the controller, and the signal from the CCD camera 9 is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device suitable for observation, photoelectric detection, processing and the like using invisible light such as infrared light and ultraviolet light.

[0002]

2. Description of the Related Art In recent years, as an example of a conventional optical device, an exposure wavelength, which has become the mainstream of a semiconductor exposure apparatus, is 436n.
A pattern to be projected (hereinafter referred to as a reticle pattern) and a projected image are transferred in a high-precision reduction projection exposure apparatus (hereinafter referred to as a stepper) using an m g line, a 365 nm i line, and a 248 nm excimer. There is an optical device for performing various positioning or signal detection by observing or photoelectrically detecting both or one of a substrate (hereinafter referred to as a wafer) through a projection lens.

Further, there is an optical device for locally exposing (processing) a wafer, a reticle pattern or the like with high accuracy.

FIG. 6 is a sectional view showing an example of such a conventional optical device. However, the projection lens and the illumination system are omitted. In such an apparatus, the wavelength used by the projection lens or the exposure sensitivity of a processed material such as a photosensitizer (hereinafter referred to as a resist) is in the ultraviolet region, so the wavelength used by the optical device must be in the ultraviolet region. . Further, since the high precision as described above is required, the optical device must be assembled and adjusted with high precision as a necessary condition for achieving the high precision, and it must be maintained. It is nothing but the placement and maintenance of the optical axes of the optical parts of the optical device with high precision. Therefore, in the conventional device, the optical axis is adjusted by using the light beam in the ultraviolet range, which is the wavelength used, or the desired reflection, transmission, or refraction characteristics are given to both wavelengths in the ultraviolet range and the visible range. It was adjusted using an optical member.

[0005]

However, the above-mentioned conventional example has the following problems. In other words, when trying to assemble and adjust the light in the ultraviolet range, the light source is inconvenient to handle, such as a mercury lamp, the intensity of the light is insufficient, or it is invisible. Has some problems in terms of production efficiency or accuracy, such as the need for some kind of conversion means, and the means must be made highly accurate. Further, since it is invisible light, there is a danger to the human body. On the other hand, using an optical member having desired optical characteristics for both wavelengths in the ultraviolet region and visible region, assembly,
If the adjustment is performed with visible light, it becomes an extremely expensive optical member, resulting in an increase in device cost. Furthermore, the optical axis monitor means for maintaining the optical axis accuracy of the optical device is not provided.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple, low-cost and highly accurate optical device in view of the above problems of the prior art.

[0007]

In order to achieve this object, according to the present invention, in an optical device provided with an optical path bending member having a reflecting surface for bending the optical path in an optical system, the reflecting surface has different spectral reflection. A plurality of reflective regions having a rate characteristic are provided on the same surface. Further, it is preferable that a plurality of optical systems are formed through the plurality of reflection regions, and the light having wavelengths adapted to their spectral reflectance characteristics is formed.

[0008]

As a result of a detailed study by the present inventor, in the optical device, it is noted that the bending member of the optical path used in the optical system has a high contribution to the accuracy and precision stability of the optical system. However, the above-mentioned configuration is adopted in order to make the apparatus compact. According to this, since the reflecting surface of the optical path bending member is provided with a plurality of reflecting regions having different spectral reflectance characteristics on the same surface, the light of the wavelength of the main observation optical system used for the original application of the device is used. Irrespective of, by observing the reflected light by irradiating visible light of other wavelengths, etc. to the reflection area having the spectral reflectance characteristic corresponding to it,
The position of the bending member can be monitored very accurately though indirectly, and the bending member can be easily and safely attached and adjusted by visible light. Moreover, mounting
Even after the adjustment, the position of the bending member is similarly monitored with light in the visible wavelength range. Therefore, it is possible to provide a highly accurate, simple, and low-cost optical device without requiring an expensive optical member or a special photoelectric detection unit.

[0009]

FIG. 1 is a sectional view of an observation apparatus using an optical device according to an embodiment of the present invention. This device uses excimer light (wavelength 248 nm) as main observation light, He-Ne laser (wavelength 633 nm) as assembly adjustment light, and LED (wavelength 630n).
m) is used as the monitor light. FIG. 2 shows A to FIG.
It is the figure seen from the A direction.

In these figures, 1 is a main body for holding an optical system, 2-1 to 4 are first optical axes which are optical axes of excimer light which is main observation light, and 3-1 to 4 are first optical axes, respectively. Axis 2-1
2nd axis parallel to 4 and having the same pitch, 4-1 to 4 are second
The reference holes for adjustment 5 arranged on the main body 1 so that the extension lines of the shafts 3-1 to 4 are coaxial with the second shafts 3-1 to 4 at positions passing through the main body 1, respectively. A reference mirror for adjustment arranged in a plane orthogonal to 1, 6 is a position not shown
Objective lens barrel held by the attitude adjusting member, 7-1
3 to 3 are optical path bending members held by a position / posture adjusting member (not shown), 8 is a relay lens barrel held by a position / posture adjusting member (not shown), and 9 is held by the main body 1 by a mechanism (not shown). CCD for observation or photoelectric detection
A camera 10 is an observation object plane composed of a transmissive object illuminated by an illumination means (not shown) using excimer light, 1
1 is a light source 12 by an LED, a condenser lens 13,
An optical axis monitor light projecting unit composed of a mirror 15, a reference mark 14, a projection lens 16 and the like, and 17 receives a light beam from the optical axis monitor light projecting unit 11 composed of an imaging lens 18, a detection unit 19 and the like. An optical axis monitor detector for detecting the position and inclination of the light beam, 20 is a He-Ne laser beam, 21 is a glass substrate which is a substrate of the optical path bending member 7-1, and 22 is an excimer which is main observation light on the glass substrate 21. A necessary area for reflecting light, 23 is a first reflection coating surface which is arranged on the glass substrate 21 and reflects excimer light. 24 is He-
The optical axis monitor light projecting unit 11 is a second reflective coating surface having a sufficient reflection characteristic for the light of the wavelength of the Ne laser and the LED, and is centered on the intersection of the second axis 3-1 and the glass substrate 21. It is arranged in a necessary area on the glass substrate 21 which reflects the light from the. In the optical path bending members 7-2 and 7-3,
The first reflection coated surface 23 and the second reflection coated surface 24 are arranged similarly to the case of the optical path bending member 7-1.
41 is a relay lens barrel surface processed to be a surface orthogonal to the optical axis of the relay lens, and 42 is an objective lens barrel processed to be a surface orthogonal to the optical axis of the objective lens. The surface.

Next, a procedure for performing assembly adjustment in this configuration will be described. (1) The He-Ne laser beam 20 is made incident on the reference mirror 5 in the direction of the arrow in the drawing, and the posture of the He-Ne laser beam 20 is adjusted so that the optical axes of the incident light and the reflected light from the reference mirror 5 coincide with each other. adjust. Next, He-Ne laser beam 2
0 is translated and the position of the He—Ne laser beam 20 is adjusted so that the He—Ne laser beam 20 enters the position coaxial with the reference hole 4. Next, the optical path bending member 7-
1 is attached to the main body 1. At this time, the second axis 3-1 and the second reflection coating surface 24 of the optical path bending member 7-1 are substantially aligned with each other and reflect the He—Ne laser beam with sufficient intensity.

(2) Next, a mirror (not shown) similar to the reference mirror 5 is arranged outside the main body 1 on the extension line of the second optical axis 3-2 (indicated by a broken line in the figure).

(3) Next, the He-Ne laser beam 20 is made incident on this mirror, and the optical path bending member 7-1 is arranged so that the incident light and the optical axis of the reflected light from the mirror coincide with each other.
Adjust the posture of.

(4) Next, at the center of the reference hole 4-2, He-
The optical path bending member 7-1 is moved in parallel so that the optical axes of the Ne laser beam 20 coincide with each other. This allows He-
Since the Ne laser beam 20 strikes the second reflective coating surface 24, sufficient light intensity can be obtained and highly accurate adjustment can be performed.

(5) Optical path bending members 7-2 and 7-
For 3 as well, adjustment is performed in order by the same procedure as in (2) to (4) above. As a result, the optical path bending members 7-2 and 7-3 are each set to the second position as in (4) above.
The second reflection coated surface 24 substantially coincides with the intersection of the optical axes 3-2 and 3-3, which enables highly accurate adjustment. The optical path bending members 7-1 to 7-1 are executed by the above steps (1) to (5).
High-precision adjustment of 3 is completed.

(6) Next, the relay lens barrel 8 is attached to the main body 1 by utilizing the lens barrel surface 41 and the like and adjusting its posture and position by a known method. Next, similarly, the objective lens barrel 6 is also attached to the main body 1 using the lens barrel surface 42.

(7) Next, the CCD camera 9 is attached to the main body 1. This completes the adjustment regarding the optical axis of the main optical system.

(8) Next, an unillustrated optical system using the excimer light as illumination light illuminates an unillustrated pattern arranged on the observation object surface 10, and the CCD camera 9 displays it on an unillustrated monitor. The relative positions of the objective lens barrel 6 and the relay lens barrel 8 are adjusted while viewing the image. This completes the focus adjustment relating to the image formation of the main optical system.

(9) Next, the optical axis monitor light projecting section 11 is attached to the main body 1 so that the optical axis thereof coincides with the second axis 3-1 and the optical axis monitor detecting section 17 is attached thereto. The optical axis is second
It is attached to the main body 1 so as to coincide with the axis 3-4.

(10) Then, the zero adjustment of the detector 19 is performed.

The above steps complete the assembly and adjustment. Of course, once the assembly and adjustment are completed, the He-Ne laser beam 2
The 0 and the adjustment reference mirror 5 are no longer necessary.

Next, the operation after the observation apparatus is mounted on the stepper or the like will be described. When the excimer light illuminates the observation object plane 10 via a reduction projection lens (not shown) or the like, the light including the optical information of the alignment mark and the focus detection mark arranged on the object plane 10 is converted into the objective lens barrel 6, The light is received by the CCD camera 9 via the optical path bending member 7-1, the relay lens barrel 8, and the optical path bending members 7-2 to 7-3. Then, based on a signal from the CCD camera 9, position information and focus information of the object plane 10 are calculated by a calculation control device (not shown), and positioning of the object plane 10 and other controls are performed.

The monitor system constantly or as needed monitors optical axis fluctuations, and when an abnormality occurs, a control device (not shown) issues a warning signal or corrects a signal from the CCD camera 9. It is like this.

FIG. 5 shows a processing apparatus to which an optical device according to another embodiment of the present invention is applied. This device is for processing the transferred material 29 by exposing and transferring the pattern provided on the transfer material 28 to the transferred material 29, and the first reflection coated surface of the optical path bending member 7-2 is half-shaped. The transfer member 28, which is composed of a mirror, is illuminated with illumination light 30 from an illumination system (not shown), and the optical path bending members 7-3 and 7- of the optical system are illuminated.
2, the transfer lens 29 is exposed and processed through the relay lens barrel 8, the optical path bending member 7-1, and the objective lens barrel 6. The CCD camera 9 is the transferred object 29.
The transferred material 29 can be observed by using the light reflected by the light transmitted through the optical path bending member 7-2. Other configurations are the same as those in the above-mentioned embodiment.

The present invention is not limited to these embodiments, but can be implemented by appropriately modifying it. For example, the reflection coated surface can have any shape, arrangement and area, and may be the first reflection coated surface 26 and the second reflection coated surface 25 as shown in FIG. Also, FIG.
As shown in FIG. 2, the second reflection coated surfaces 27-1 to 27-4 may be provided at four locations on the first reflection coated surface 26. The first reflection coated surface can also be formed in any shape as long as it covers the excimer light reflection area.

It is also possible to use light having a wavelength other than the excimer light as the observation light or the detection light. Light having a wavelength other than the He-Ne laser can also be used as light for adjustment by making the second reflection coating surface correspond to the wavelength. Furthermore, observation / adjustment may be performed using light of two or more types of wavelengths.

[0027]

As described above, according to the present invention, the reflecting surface of the optical path bending member is provided with a plurality of reflecting regions having different spectral reflectance characteristics on the same surface, and further the spectral reflectance characteristics thereof are Since a plurality of optical systems for different lights are provided, these optical systems are used, for example, as the main observation system, assembly adjustment system, monitor system, etc., and light of visible wavelength is used for the assembly adjustment system and monitor system. can do. Therefore, an expensive optical member, special photoelectric detection, etc. are not required, and the cost of the optical device can be reduced. Further, a monitor optical system for monitoring and correcting the change with time of the optical system can be realized simply and at low cost, so that the optical device can be maintained with high accuracy, which contributes to the improvement of productivity. be able to. Further, since it is not necessary to use a special light source for assembly and adjustment, the production cost can be reduced and the safety for the human body can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an observation apparatus using an optical device according to an embodiment of the present invention.

FIG. 2 is a view seen from the direction AA of FIG.

FIG. 3 is a schematic view showing another example of the bending member in the device of FIG.

FIG. 4 is a schematic diagram showing still another example of the bending member in the apparatus of FIG.

FIG. 5 is a cross-sectional view showing a processing device to which an optical device according to another embodiment of the present invention is applied.

FIG. 6 is a cross-sectional view showing an example of a conventional optical device.

[Explanation of symbols]

1: Optical device body, 6: Objective lens barrel, 7-1 to 3:
Optical path bending member, 8: relay lens barrel, 9: CCD
Cameras, 11: optical axis monitor light projecting section, 17: optical axis monitor light receiving section, 21: glass substrate, 23, 26: first reflective coated surface, 24, 25, 27: second reflective coated surface.

Claims (2)

[Claims] 1. An optical device comprising an optical path bending member having a reflection surface for bending the optical path in an optical system, the reflection surface having a plurality of reflection regions having different spectral reflectance characteristics on the same surface. An optical device characterized by: 2. A plurality of optical systems for transmitting light having wavelengths respectively adapted to the spectral reflectance characteristics of the plurality of reflective areas, respectively, to form a plurality of optical systems. Optical device.