JPH08203803A - Exposure apparatus - Google Patents

Abstract

PURPOSE: To achieve high precision detection of the light from an optical integrator by destroying the image forming relationship in an optical system through the diffusion action due to diffusion means such as a lemon-skin filter to eliminate the limitation on the disposition of photo-electric detecting means. CONSTITUTION: Part of light flux from many light source images I21 -2n , formed on the emitting side surface 4b of an optical integrator 4, is reflected by a half-mirror 5 and focused by a focusing lens 7, and then incident on a lemon-skin filter 9 having a function as diffusion means. Thereupon, the image forming relationship in the optical system is completely destroyed by the diffusion action due to the lemon-skin filter 9, and divergent ligh DR is produced randomly, and this randomly produced light is detected by a photo-electric detector 8. Thus, the limitation on the disposition of the photo-electric detector 8 is completely eliminated by the diffusion effect due to the lemon-skin filter 9, and high precision detection of the light from the optical integrator 4 is achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus suitable for manufacturing semiconductor elements such as LSI and VLSI, liquid crystal and the like.

[0002]

2. Description of the Related Art As a conventional exposure apparatus, for example, the one disclosed in Japanese Patent Laid-Open No. 61-71631 is known, and the configuration disclosed in this publication is shown more clearly in FIG. A configuration as shown is possible. It should be noted that in FIG.
The collimator lens 3 is added to the configuration disclosed in the publication.

As shown in FIG. 6, the light from the light source 1 is an elliptical mirror.
The light source image I ₁After the formation of
This light source image I₁The light flux from the collimator lens 3
Are converted into collimated light (parallel light flux). This Colime
When the optical light passes through the optical integrator 4,
Multiple light sources on the exit side of the optical integrator 4
Image I_2n(Many secondary light sources) are formed,
The circuit pattern of the luminous flux is shaped by the condenser lens 6.
The mask M to be formed is illuminated in a superimposed manner to the mask M.
And a mask M on the wafer W arranged at a predetermined interval.
Pattern is transferred.

On the other hand, a half mirror 5 is obliquely provided between the optical integrator 4 and the condenser lens 6, and the light flux reflected by the half mirror 5 is optically passed through the condenser lens 7 and the mask M. Photoelectrically detected by the photoelectric detector 8 for illuminance measurement arranged at a position conjugate with. Here, the light receiving surface 8a of the photoelectric detector 8 is a mask M
The reason why it is arranged at a position optically conjugate with will be described with reference to FIG. In FIG. 7, in order to facilitate understanding, the optical integrator 4 is set to 3 in the plane of the drawing.
The case where it is configured by two lens elements is shown.

In FIG. 7, the incident side surface 4a of the optical integrator 4 and the mask M are as shown by a dotted line.
Optical integrator 4 and condenser lens 6
The light fluxes from the plurality of light source images (I _{21 to} I ₂₃ ) formed on the exit side surface 4b by the optical integrator 4 pass through the half mirror 5 and then pass on the mask M by the condenser lens 6. Illuminate in a superimposed manner.

On the other hand, the incident surface 4a of the optical integrator 4 and the light receiving surface 8a of the photoelectric detector 8 are in a conjugate relationship with respect to the optical integrator 4 and the condenser lens 7 as shown by a dotted line, and the optical integrator 4 emits light from the side surface. A plurality of light source images (I
The light fluxes from _{21 to} I ₂₃ ) are reflected by the half mirror 5 and then illuminate the light receiving surface 8a of the photoelectric detector 8 in a superimposed manner by the condenser lens 7.

Therefore, the uniform illumination distribution formed on the surface of the mask M is reproduced on the light receiving surface 8a of the photoelectric detector 8, and the position of the light source 1 (the position of the light source 1 itself or the light source 1) is reproduced.
Even if the position of the bright spot 1a of the mask M fluctuates in the A direction or the B direction, the detection light superimposing effect by arranging the light receiving surface 8a of the photoelectric detector 8 optically conjugate with the mask M It is possible to detect the illuminance equivalent to that of the surface with high accuracy, and it is possible to appropriately control the exposure amount.

[0008]

However, in the conventional apparatus as shown in FIGS. 6 and 7, it is necessary to accurately arrange the photoelectric detector 8 at a position conjugate with the mask M. Adjustments for accurate placement were very troublesome. Further, as a result of many experiments and studies, even if the light receiving surface 8a of the photoelectric detector 8 is arranged at a position that is conjugate with the mask M and the optical system, the photoelectric detector 8 will not be on the mask surface. It turned out that the illuminance distribution almost the same as was not reproduced. The first reason for this is that the half mirror 5 that splits the light from the optical integrator 4 has uneven transmittance and uneven reflectance depending on the angle. However, it is impossible to completely remove these irregularities.

The second reason is that, first of all,
Transfer a fine mask pattern onto the wafer and
As an exposure apparatus for manufacturing liquid crystal or the like, on the mask M
Illuminance distribution of illuminating light is about 3% or less.
It must be removed to make it almost completely uniform. In addition, Teru
The unevenness S is the illuminance of the illuminance distribution formed on the mask surface.
The maximum value of_maxAnd the amount of illuminance formed on the mask surface
The maximum value of the illuminance of the cloth is S _minIs given by
Things.

S = (S _max −S _min ) / (S _max + S _min ) Therefore, in order to suppress the illumination unevenness on the mask M to about 3% or less, the illumination light is illuminated on the mask M in a superimposed manner. The actual condenser lens 6 is composed of a large number of optical members such as lenses, and various aberrations are corrected to a high level by the condenser lens 6 so that the condenser lens 6 is in a nearly aberration-free state.

However, in the conventional apparatus shown in FIGS. 6 and 7, the condenser lens 7 is composed of a small number of lenses, such as about one sheet, in order to miniaturize the photoelectric detection system.
With this condenser lens 7, it is impossible to correct the aberration to the level where the condenser lens 6 corrects the aberration. As a result, in the conventional device, the illuminance distribution close to the illuminance distribution formed on the mask surface is obtained by the light receiving surface 8a of the photoelectric detector 8.
It was impossible to reproduce in.

The present invention solves the above problems, eliminates the restrictions on the arrangement of the detection system for detecting the light from the optical integrator, and detects the light from the optical integrator with much higher accuracy than before. It is an object of the present invention to provide a high-performance exposure apparatus to be obtained.

[0013]

In order to achieve the above object, the present invention provides a light source means for supplying a light flux and a large number of light sources based on the light flux from the light source means, for example, as shown in FIG. And a condenser optical system for converging light beams from a large number of light sources formed by the multi-light source forming means to illuminate an original plate on which a predetermined pattern is formed in a superimposed manner. In an exposure apparatus that exposes the pattern of the original plate on a substrate, light splitting that guides a part of the light flux from the multiple light source forming means in a predetermined direction in an optical path between the multiple light source forming means and the condenser optical system. And a photoelectric detection means for photoelectrically detecting a part of the light beam guided in the predetermined direction by the light splitting means, and an optical path between the light splitting means and the photoelectric detection means. Inside said many The light beam from the multiple light sources formed by the source forming means is obtained by arranging the light diffusing means for diffusing.

[0014]

[Operation] In the present invention, the arrangement of the light diffusing means eliminates the restrictions on the arrangement of the photoelectric detecting means and the complexity of the adjustment, and moreover, the illuminance on the light receiving surface of the photoelectric detecting means by the diffusing action of the light diffusing means. Since the uniformity is increased, it is possible to reproduce an illuminance distribution that is as close as possible to the illuminance distribution formed on the illuminated surface on which the original plate such as a mask is arranged, even on the light receiving surface of the photoelectric detection means.

[0015]

FIG. 1 is a diagram showing an embodiment according to the present invention,
In FIG. 1, members having the same functions as those in FIG. 6 described above are designated by the same reference numerals. As shown in FIG. 1, an ultra-high pressure mercury lamp 1 as a light source has a light emitting point 1a (bright spot) thereof.
Is arranged so as to coincide with the first focal position of the elliptic mirror (reflecting mirror) 2, and the luminous flux emitted from the extra-high pressure mercury lamp 1 is condensed at the focal position of the elliptic mirror 2 to form a light source image. Form I ₁ . The light source means is composed of the light source 1 and the elliptical mirror 2.
And a collimator lens 3. A shutter 12, which will be described later, is arranged at or near this light source image I ₁ .

The light flux from the light source image I ₁ is converted into collimated light (parallel light flux) by the collimator lens 3, and this collimated light is incident on the optical integrator 4 serving as a multiple light source forming means, and the optical integrator 4 of the optical integrator 4 is operated. A large number n of light source images (I _{21 to} I _2n ) are formed on the exit side surface 4b in the paper surface direction. The optical integrator 4 is composed of a fly-eye lens composed of an assembly of lens elements having a quadrangular lens cross section such as a square shape or a rectangular shape, or a regular hexagonal lens cross section. The optical integrator 4 may be formed of an inner surface reflection type hollow member in which the inner surface of the hollow member is formed of a reflecting surface, or a reflection type optical member formed to reflect the inner surface of a rod-shaped optical member. In this case, the internal reflection type hollow member and the reflection type optical member may have any cross section such as a quadrangle or a hexagon.

Now, the light beams from a large number of light source images (I _{2a to} I _2g ) formed on the exit side surface 4b of the optical integrator 4 have a predetermined reflectance (for example, several% to several tens%) as a light splitting means. A half mirror 5 having a reflectance of 2) splits the light beam into two light beams which respectively travel in the transmission direction and the reflection direction. The light flux passing through the half mirror 5 is guided to a condenser lens 6 as a condenser optical system, and the light flux reflected from the half mirror 5 is guided to a photoelectric detection system described later.

Light fluxes from a large number of light source images (I _{21 to} I _2n ) incident on the condenser lens 6 are condensed by the condenser lens 6 and the mask M as an original plate on which a predetermined circuit pattern is formed is effective. Illuminate the area in a superimposed manner. Although the condenser lens 6 is shown as a single lens in FIG. 1 for the sake of simplicity, the actual condenser lens 6 has an uneven illuminance of 3% in the effective illumination area of the mask M as described above. In order to satisfactorily correct various aberrations to the extent that it can be suppressed to the following, it is composed of a large number of optical members such as five to ten and several lenses.

As described above, when the mask M is uniformly illuminated, the mask is provided under a predetermined projection magnification by the projection optical system PL composed of two refracting lens groups (G ₁ , G ₂ ). The pattern image on M is projected and exposed on a wafer W (photosensitive substrate) coated with a photosensitive material (resist). In addition,
The mask M is held by the mask stage MS, and the wafer W is held by the wafer stage WS. Further, the projection optical system PL is not limited to having a reduction magnification, but may have a configuration having a unity magnification and an enlargement magnification. Furthermore, the projection optical system PL is not limited to the case where the projection optical system PL is composed of a refraction system.
A reflective system or a catadioptric system may be used.

Now, with the half mirror 5 described above,
A large amount of light emitted from the optical integrator 4
A photoelectric detection system that detects a bundle will be described. Optica
A large number of parts formed on the exit side surface 4b of the ruintegrator 4
Light source image (I _{twenty one}~ I_2n) Part of the luminous flux from
After being reflected by -5, it is subjected to a condensing function by condensing lens 7.
Lens skin filter that has the function of diffusing means
It is incident on the Luther 9. Then the lemon skin filter
Due to the diffusion effect of 9, the optical image formation relationship is completely destroyed.
The diffused light DR is generated randomly, and this random
The generated diffused light is detected by the photoelectric detector 8.

When the photoelectric detector 8 photoelectrically detects the diffused light DR, the photoelectric detector 8 outputs a detection signal, which is input to an exposure amount control system 10 as an exposure amount control means. Then, the exposure amount control system 10 calculates the integrated exposure amount with time, and when the appropriate exposure amount is reached, the drive system 1
The shutter 12 that blocks the illumination light via 1 is rotated in the direction of the arrow, and the shutter 12 is controlled so as to be inserted into the illumination light path (at or near the position of the light source image I ₁ formed by the elliptical mirror). With the above configuration, appropriate management of the exposure amount of the exposure apparatus is performed.

Now, a method of manufacturing the lemon skin filter 9 will be described. As shown in FIGS. 2 (a) and 2 (b), the shape of the lemon skin filter 9 is circular (or rectangular), and both surfaces are matte surfaces subjected to lemon skin processing. When the lemon skin filter 9 is formed by rough-shearing the surface of the flat plate P and then sanding it with abrasive grains of about # 700, FIG.
As shown in, the sanded rough surface has a roughness of 5 μm. Then, a chemical treatment is applied to the roughened surface using hydrofluoric acid, so that as shown in FIG. 3B, a large number of fine spherical surfaces (fine curved surfaces) are formed by smoothing the projections of fine irregularities on the roughened surface. Lemon skin filter 9 can be obtained. Although FIG. 3 shows an example in which one surface of the plane plate P is processed to form the lemon skin, both surfaces may be processed to form the lemon skin.

For this reason, the surface of the lemon skin filter 9 functions as if a myriad of micro lenses were arranged. When the lemon skin filter 9 is arranged together with the condenser lens 7 between the half mirror 5 and the photoelectric detector 8 as shown in FIG. 4, since the lemon skin filter is an assembly of innumerable microlenses, the photoelectric detector 8 And the reticle conjugate relation is completely broken.

Next, the operation of the lemon skin filter 9 will be described with reference to FIG. FIG. 4 is an enlarged view of the peripheral portion of the photoelectric detection system of FIG. 1, and FIG. 7 shows a case where the optical integrator 4 is composed of three lens elements in the paper surface direction for easy understanding.
As shown in FIG. 4, since the lemon skin filter 9 is arranged in the optical path reflected by the half mirror 5,
The effect (averaging effect) that the superimposing property of the light flux from each light source image (I _{21 to} I ₂₁ ) increases as the distance from the many light source images (I _{21 to} I ₂₃ ) formed on the exit side surface 4b of the optical integrator 4 increases. And the diffusion effect of the lemon skin filter 9 completely destroys the optical image formation relationship and the diffused light DR advances in a random (arbitrary) direction in a superimposing effect (averaging effect). Therefore, a uniform illuminance distribution that is as close as possible to the illuminance distribution formed on the mask M is reproduced on the light receiving surface 8a of the photoelectric detector 8.

Therefore, as shown in FIG. 1, there is no influence even when the position of the mercury lamp 1 (the position of the mercury lamp 1 itself or the position of the bright spot 1a of the mercury lamp 1) fluctuates in the A direction or the B direction. It is possible to realize highly accurate and stable detection of the exposure amount under the illuminance that matches the illuminance on the mask M. Therefore, the condensing lens 7 basically needs only to have a function of condensing light, and can be configured with an extremely small number of lenses.

The condenser lens 7 has an effect of efficiently collecting the light fluxes from the respective light source images in a small space, the superimposing effect of which increases as the distance from the many light source images formed on the exit side surface 4b of the optical integrator 4 increases. . The light-receiving surface 8a of the photoelectric detector 8 can be set at an arbitrary position due to the diffusion effect of the lemon skin filter 9 described above, and the mask M and the light-receiving surface 8a of the photoelectric detector 8 are optically conjugate with each other in the past. In order to achieve this, the restriction on the arrangement of the photoelectric detector 8 that must be arranged on the light receiving surface 8a of the photoelectric detector 8 at the rear focal position of the condenser lens is not only completely solved, but also the photoelectric detector It becomes possible to greatly save the trouble of adjustment by the arrangement of 8.

Further, since the lemon skin filter-9 is an assembly of minute micro lenses,
Even if the illuminance is slightly uneven in the light divided by 5, the lemon skin filter 9 illuminates the photoelectric detector 8 in a superimposed manner like an optical integrator, so that the effect of the illuminance unevenness is less likely to occur. To have. This is particularly effective when the half mirror 5 has a dielectric thin film deposited on the glass surface and there is uneven reflectance due to the angle characteristics of the incident light.

In the above embodiments, the degree of roughness of the lemon skin filter is set to 5 μm, but it is not limited to 5 μm without any problem as long as the roughness is sufficiently larger than the wavelength. That is, the abrasive grain # 700 in the sanding step is not limited to this. Further, since the structure having innumerable microlenses is important, the diffuser plate having the same effect, and the one which can be regarded as a lemon skin filter after being subjected to other chemical treatments naturally have the effect of the present invention. It is not limited to lemon skin filters.

For example, if the surface roughness of the lemon skin filter 9 is configured to be sufficiently rough, the directional characteristics shown in FIG. It does not lose most of the energy like the photodetector 8
Can be taken into. In the above embodiment, the lemon skin filter 9 as the diffusing means is arranged in the optical path between the condenser lens 7 and the photoelectric detector 8.
In the present invention, the condenser lens 7 is not always essential,
The condenser lens 7 is removed, the light flux from the optical integrator 4 guided to the photoelectric detection system via the half mirror 5 is diffused by the lemon skin filter 9, and this diffused light is detected by the photoelectric detector 8. Even with such a configuration, the effect of the present invention is not lost at all. The reason is
As described above, the effect of increasing the superimposing property of the light flux from each light source image (I _{21 to} I _2n ) as the distance from the many light source images (I _{21 to} I _2n ) formed on the exit side surface 4b of the optical integrator 4 increases ( The averaging effect) and the superimposing effect (averaging effect) due to diffused light proceeding in a random (arbitrary) direction due to the complete disruption of the optical imaging relationship due to the diffusion effect of the lemon skin filter 9 This is because a uniform illuminance distribution, which is as close as possible to the illuminance distribution formed on the mask M, is reproduced on the light receiving surface 8a of the photoelectric detector 8 because it acts on the mask M.

Also, diffused light randomly generated by the lemon skin filter 9 in the optical path between the lemon skin filter 9 and the photoelectric detector 8 is efficiently guided to the light receiving surface of the photoelectric detector 8 for collecting the diffused light. It goes without saying that a lens may be arranged. Further, in the above embodiments, the photoelectric detection system (7, 8, 9) is provided in the reflection direction of the half mirror 5.
Although the example in which the exposure system (6, PL) is arranged in the transmission direction of the half mirror 5 is shown, the photoelectric detection system (7, 8, 9) is exposed in the transmission direction of the half mirror 5 and the reflection direction of the half mirror 5 is exposed. The system (6, PL) may be arranged.

Further, although the embodiments explained above have been explained based on the projection type exposure apparatus, the present invention is a proximity type exposure apparatus for exposing by exposing a mask and a substrate such as a wafer, An exposure apparatus for liquid crystal production that exposes a mask pattern onto a large-sized substrate under equal magnification, and a mask and a substrate (large-sized substrate, wafer, etc.) for the projection optical system PL.
It is needless to say that the present invention can be applied to a scanning type exposure apparatus that moves a lens to perform projection exposure.

[0032]

As described above, according to the present invention, the image forming relationship of the optical system is destroyed by the diffusing action of the diffusing means such as a lemon skin filter. There is no need to optically conjugate with the illuminated surface. Therefore, there is an effect that not only restrictions on the arrangement of the photoelectric detection means are completely eliminated, but also adjustment at the time of arrangement of the light receiving means is almost unnecessary. Further, even when there is illumination unevenness in the light flux incident on the photoelectric detection means, the superimposing effect (averaging effect) due to the diffusion effect of the diffusion means such as the lemon skin filter works effectively. An illuminance distribution close to the illuminance distribution formed above can be reproduced on the detection surface of the photoelectric detection means. This makes it possible to realize an exposure apparatus that can perform exposure control with high accuracy and stability.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

2A is a perspective view of the lemon skin filter 9, and FIG. 2B is a cross-sectional view of the lemon skin filter 9.

FIG. 3 (a) is a diagram schematically showing a first processing step in producing the lemon skin filter 9, and FIG. 3 (b) is a second processing step in producing the lemon skin filter 9. It is a figure which shows a process typically.

FIG. 4 is a diagram showing a state in which a peripheral portion of the photoelectric detection system in FIG. 1 is enlarged.

FIG. 5 is a diagram showing a state of a photoelectric detection system when the surface roughness of a lemon skin filter 9 is roughened.

FIG. 6 is a diagram showing a conventional configuration.

FIG. 7 is a diagram showing a state in which a peripheral portion of the photoelectric detection system in FIG. 6 is enlarged.

[Explanation of symbols]

 1 ・ ・ ・ Ultra high pressure mercury lamp 2 ・ ・ ・ ・ ・ ・ Elliptical mirror 3 ・ ・ ・ ・ ・ ・ ・ Collimating lens 4 ・ ・ ・ ・ ・ ・ ・ Optical integrator 5 ・ ・ ・ ・ ・ ・ ・Half mirror 6 ... Condenser lens 7 ... Condensing lens 8 ... Photoelectric detector 9 Lemon skin filter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display point 525 N

Claims (1)

[Claims] 1. A light source means for supplying a light flux, a multi-light source forming means for forming a large number of light sources based on the light flux from the light source means, and a light flux for a plurality of light sources formed by the multi-light source forming means. A condenser optical system for converging and illuminating an original plate on which a predetermined pattern is formed, and exposing the original plate pattern onto a substrate, wherein the multiple light source forming means and the condenser optical system are provided. A light splitting means for guiding a part of the light flux from the multi-light source forming means in a predetermined direction is arranged in an optical path between and, and a part of the light flux guided in the predetermined direction by the light splitting means is photoelectrically converted. And a photoelectric diffusing unit for diffusing light beams from a large number of light sources formed by the multiple light source forming unit in the optical path between the light dividing unit and the photoelectric detecting unit. Exposure and wherein the a.