JPH11354409A - Illuminator, projection aligner provided there with, and manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a uniform illuminance distribution by suppressing uneven illumination on an exposed surface, so as to sufficiently cope with required delicate micro-machining. SOLUTION: A illuminator is provided with a correction optical system 10 in addition to various kinds of optical systems which are the components of a stepper. When, for example, the nitrogen in a room 10b is partially replaced with oxygen, light absorption occurs in the room 10b as luminous fluxes La, Lb, and Lc pass through the room 10b. Since the distances of the fluxes La, Lb, and Lc when they pass through the room 10b are La<Lb<Lc, the absorbed amounts of the fluxes La, Lb, Lc become different from each other and the illuminance distribution on the light emitting surface of the correction optical system 10 shows a descending distribution towards right side. A uniform illuminance distribution is obtained by changing the oxygen concentration of the optical system 10 or the wavelength of a light source, so that the uneven illuminance on the surface of a wafer which is a surface to be irradiated may be offset by utilizing this nature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device and a projection exposure apparatus having the same, and more particularly to a semiconductor device such as an IC or LSI, an imaging device such as a CCD, a display device such as a liquid crystal panel, and various devices such as a magnetic head. TECHNICAL FIELD The present invention relates to an illumination device used for manufacturing a semiconductor device, a projection exposure apparatus including the same, and a method for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In recent years, further miniaturization and high integration of semiconductor devices such as ICs and LSIs have been progressing, and accordingly, projection exposure apparatuses used for manufacturing the semiconductor devices have been required to have a large surface area on a wafer surface. Is required to have an extremely high optical performance with a minimum line width of 0.2 μm or less.

Generally, when a circuit pattern on a reticle surface is projected onto a wafer surface (projection surface) via a projection optical system, the resolution line width of the circuit pattern depends on the wavelength of a light source used and the projection optical system. The uniformity of the illuminance distribution on the projection surface together with the NA (numerical aperture) and the like greatly influences the exposure result.

In particular, when the minimum line width is 0.2 μm or less, a short-wavelength ArF excimer laser (wavelength: about 193 nm) or the like is proposed as a light source, and the illuminance distribution on the surface to be projected is low. As for the uniformity, it is required that the illuminance unevenness is within about 1%.

FIG. 13 is a schematic view of an essential part showing an example of an optical system of a conventional projection exposure apparatus. In FIG.
Is collected by an optical system 72, and is incident on an incident surface 73a of an optical integrator 73 in which a plurality of minute lenses are two-dimensionally arranged. Then, a plurality of secondary light sources are formed on the emission surface 73b of the optical integrator 73. Illumination light from a plurality of secondary light sources formed on the emission surface 73b is condensed by the condenser lens 74, and illuminates the surface 75 while overlapping.

A reticle R on which a predetermined circuit pattern is formed is arranged on the surface 75, and the circuit pattern on the reticle R surface is projected and imaged on the projection surface 77 of the wafer W by the projection lens 76. . At this time, the secondary light source on the exit surface 73b of the optical integrator 73 is formed near the pupil 76a of the projection lens 76 by the condenser lens 74.

[0007]

When the above configuration is adopted, the illuminance distribution on the incident surface of each of the minute lenses constituting the optical integrator 73 overlaps on the projection surface 77, and the projection surface 77 is illuminated. Therefore, as the illuminance distribution on the projection target surface 77, uniformity of illuminance non-uniformity of about several% to 10% is achieved. However, it is difficult to satisfy the demand that the illuminance unevenness is within 1% only by the contribution of the optical integrator 73.

[0008] Illuminance unevenness is caused by factors such as light source distribution shape, eccentricity of the light source and the optical system, coating unevenness and film thickness error, transmittance difference due to the bending mirror and the half mirror, and dust and dirt in the optical system. Various things can be considered.

Therefore, in a conventional projection exposure apparatus, a plurality of condenser lenses having different distortions (distortions) are prepared in order to change the ratio of the peripheral illuminance to the on-axis, and the optimum condenser lens is provided for each projection exposure apparatus. Select and use a lens, or configure a condenser lens as a zoom lens and adjust it to optimal illuminance unevenness according to the case, or use the tilt component of illuminance unevenness (tilt unevenness: right is higher than left For example, the position of a light source or an optical system has been adjusted as a means for adjusting (unevenness, etc.).

However, these adjustment methods make use of aberrations and eccentricity of the optical system itself, and have a fatal disadvantage that adjusting the illuminance unevenness changes the imaging performance on the surface to be projected. there were.

An object of the present invention is to provide an illuminating device capable of achieving a uniform illuminance distribution by suppressing illuminance unevenness on a surface to be illuminated (projected surface) without decentering the optical system. It is in.

It is another object of the present invention to provide the above-described illumination device, to achieve a uniform illuminance distribution by suppressing illuminance unevenness on an exposure surface, and to sufficiently cope with required fine processing. To provide a projection exposure apparatus.

[0013]

An illumination device according to the present invention is an illumination device for irradiating an illuminating light to a surface to be illuminated, and has an enclosed space having a different optical path length depending on a position through which the illuminating light passes. The illuminance distribution on the surface to be illuminated is adjusted by changing the state of a substance constituting a fluid in the closed space.

[0014] One embodiment of the illumination device of the present invention has means for obtaining illuminance distribution information on the surface to be illuminated, and based on the illuminance distribution information obtained by the means, the inside of the closed space is determined. Changes the state of the substance constituting the fluid.

In one embodiment of the lighting device of the present invention,
The fluid in the closed space is a gas having a property of absorbing the illumination light having a predetermined wavelength.

One embodiment of the lighting device of the present invention has a plurality of the closed spaces, and can independently change a state of a substance constituting a fluid in each of the closed spaces.

An illumination device according to the present invention is an illumination device for irradiating illumination light to a surface to be illuminated, and adjusts the illuminance distribution on the surface to be illuminated by changing the wavelength of the illumination light.

In one embodiment of the lighting device of the present invention,
Obtaining illuminance distribution information on the illuminated surface, and adjusting the illuminance distribution on the illuminated surface to a desired state based on the illuminance distribution information.

An illuminating device according to the present invention is an illuminating device for irradiating illumination light onto a surface to be illuminated. The illumination device changes the illuminance distribution on the surface to be illuminated by changing the state of a fluid present in the optical path of the illumination light. adjust.

In one embodiment of the lighting device of the present invention,
Obtaining illuminance distribution information on the illuminated surface, and adjusting the illuminance distribution on the illuminated surface to a desired state based on the illuminance distribution information.

In one embodiment of the lighting device of the present invention,
The fluid is a gas having a property of absorbing the illumination light having a predetermined wavelength.

A projection exposure apparatus according to the present invention includes the illuminating device, and performs exposure by projecting a predetermined pattern onto a wafer surface as the illuminated surface.

The illumination device according to the present invention is an illumination device for directing light from a light source to an illuminated surface through an optical system, wherein the illuminance or the illuminance distribution information on the illuminated surface is used for the illumination system. The ratio of the atmosphere component in at least a part of the optical system is controlled.

In one embodiment of the lighting device of the present invention,
By controlling the oxygen concentration, the ratio of the atmosphere components is controlled.

In one embodiment of the lighting device of the present invention,
The light source includes light having a wavelength in the range of 192 nm to 194 nm.

In one embodiment of the lighting device of the present invention,
The light source is an ArF excimer laser.

In one embodiment of the lighting device of the present invention,
The wavelength of the light source is variable.

A projection exposure apparatus according to the present invention includes the illumination device, and performs exposure by projecting a predetermined pattern onto the wafer surface, which is the surface to be irradiated.

In one embodiment of the projection exposure apparatus according to the present invention, the oxygen concentration in at least a part of the optical system is controlled based on the illuminance distribution information and the exposure amount information on the wafer surface.

In the illumination device of the present invention, a light source that emits illumination light and a fluid having a property of absorbing the illumination light are sealed therein at least, and the absorptance of the illumination light varies depending on the position through which the illumination light passes. And an optical system for directing the illumination light to the surface to be illuminated through the enclosed space, and utilizing the difference in the absorptance of the illumination light, on the surface to be illuminated. Adjust the illuminance distribution of.

In one embodiment of the lighting device of the present invention,
The illuminance distribution on the illuminated surface is adjusted by changing a state of a substance constituting the fluid in the closed space.

In one embodiment of the lighting device of the present invention,
By changing the wavelength of the illumination light, the illuminance distribution on the illuminated surface is adjusted.

In one embodiment of the lighting device of the present invention,
The optical system includes a lens group for directing the illumination light toward a surface to be illuminated, and a correction optical system having the closed space and arranged independently of the lens group.

In one embodiment of the lighting device of the present invention,
The optical system includes a lens group for directing the illumination light to the surface to be irradiated, and the closed space is formed between predetermined lenses constituting the lens group.

In one embodiment of the illumination device of the present invention, a detecting means for detecting illuminance distribution information on the surface to be illuminated, and the optical system is controlled in accordance with the illuminance distribution information from the detecting means. Correction means for changing a state of a substance constituting the fluid in the closed space.

One embodiment of the illumination device according to the present invention comprises a detecting means for detecting illuminance distribution information on the surface to be illuminated, and controlling the light source in accordance with the illuminance distribution information from the detecting means. Correction means for changing the wavelength of the illumination light.

In one embodiment of the lighting device of the present invention,
The fluid is a mixed gas containing oxygen, and the illuminance distribution on the surface to be irradiated is adjusted by changing the oxygen concentration.

One embodiment of the lighting device of the present invention has a plurality of the closed spaces, and can independently change a state of a substance constituting a fluid in each of the closed spaces.

The illumination device of the present invention is arranged such that a light source for emitting illumination light and a gas having at least a property of absorbing the illumination light are sealed therein and the absorptance of the illumination light varies depending on the position through which the illumination light passes. An optical system that directs the illumination light to the surface to be illuminated through the closed space, a detecting unit that detects illuminance distribution information on the surface to be illuminated, and the detecting unit Correction means for changing the concentration of the gas in the closed space according to the illuminance distribution information to adjust the illuminance distribution on the irradiated surface.

In the lighting device of the present invention, a light source that emits illumination light and a gas having at least the property of absorbing the illumination light are sealed therein so that the absorptance of the illumination light varies depending on the position through which the illumination light passes. An optical system that directs the illumination light to the surface to be illuminated through the closed space, a detecting unit that detects illuminance distribution information on the surface to be illuminated, and the detecting unit Correction means for controlling the light source in accordance with the illuminance distribution information to change the wavelength of the illuminating light to adjust the illuminance distribution on the illuminated surface.

According to the illumination device of the present invention, the light source that emits the illumination light and at least a gas having the property of absorbing the illumination light are sealed therein so that the absorption rate of the illumination light varies depending on the position through which the illumination light passes. An optical system that directs the illumination light to the surface to be illuminated through the closed space, a detecting unit that detects illuminance distribution information on the surface to be illuminated, and the detecting unit In accordance with the illuminance distribution information, while changing the concentration of the gas in the enclosed space, controlling the light source to change the wavelength of the illumination light, and adjusting the illuminance distribution on the illuminated surface Means.

In one embodiment of the lighting device of the present invention,
The closed space is configured such that a plurality of types of gases including a gas having a property of absorbing the illumination light are sealed therein.

One embodiment of the lighting device of the present invention has a plurality of the closed spaces, and can independently change the state of the substance constituting the fluid in each of the closed spaces.

The projection exposure apparatus according to the present invention is a projection exposure apparatus for exposing a predetermined pattern to a wafer surface, which is a surface to be irradiated, and irradiates a reticle having a pattern similar to the predetermined pattern with illumination light. Said lighting device for;
A projection optical system for projecting the similar pattern of the reticle onto the wafer surface so as to become the predetermined pattern.

In the method of manufacturing a semiconductor device according to the present invention, a step of applying a photosensitive material to a wafer surface and a step of exposing a predetermined pattern to the wafer surface to which the photosensitive material has been applied using the projection exposure apparatus. And developing the photosensitive material that has been exposed to the predetermined pattern.

[0046]

According to the illumination device of the present invention, when the illumination light emitted from the light source passes through the enclosed space, the illumination light depends on the wavelength of the illumination light and the state of the fluid in the enclosed space. Is absorbed and the illuminance decreases. Here, since the enclosed space is configured such that the optical path length of the illumination light differs depending on the position through which the illumination light passes, that is, the absorption rate of the illumination light differs, the illumination light passing through the enclosed space is partially The illuminated surface is illuminated with different illuminance distributions. In the present invention, by utilizing this property, the state of the substance constituting the fluid in the enclosed space is changed, or the wavelength of the illumination light is changed to adjust the illuminance distribution on the surface to be irradiated. The illuminance unevenness on the irradiation surface is canceled, and an extremely uniform illuminance distribution on the irradiation surface can be obtained.

Here, a preferable example of the fluid sealed in the closed space is a mixed gas containing oxygen. In this case, the illuminance distribution can be changed by adjusting the oxygen concentration (partial pressure) or changing the wavelength of the illumination light while keeping the oxygen concentration constant. Since the concentration of the gas can be adjusted relatively easily and accurately,
It is possible to uniform the illuminance distribution with high accuracy.

Further, the closed space may be provided between the light source and the surface to be illuminated, and as a specific example, a correction optical system having the closed space is independently installed, or illumination light is irradiated. A part of the space formed in the lens group directed to the surface may be used. As described above, in the lighting device of the present invention, the best form of sealing is provided in various parts depending on the case according to the configuration of the light source and the lens group, the positional relationship of the irradiated surface, the degree of the illuminance distribution, and the like. A space can be provided, and fine illuminance distribution adjustment is possible.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some preferred embodiments in which the present invention is applied to a reduction type projection exposure apparatus called a stepper will be described below.

(First Embodiment) First, a first embodiment will be described. FIG. 1 is a schematic diagram illustrating a main configuration of the stepper according to the first embodiment. This stepper
An illuminating device 20 for irradiating the reticle 11 on which a desired pattern is drawn with illuminating light, and illuminating light that has passed through the reticle 11 is incident and the reticle 11 pattern is
The projection optical system 12 has a projection optical system 12 for reducing projection onto the surface of the wafer 3, a wafer chuck 14 on which a wafer 13 is mounted and fixed, and a wafer stage 15 on which the wafer chuck 14 is fixed.

The illumination device 20 has an optical system for directing illumination light to a predetermined portion on the reticle 11 and an illuminance unevenness adjustment unit for adjusting the illuminance distribution of the illumination light on the surface of the wafer 13. I have.

The optical system includes a light source 1 that emits short-wavelength light such as ultraviolet light or far ultraviolet light, here a high-brightness ArF excimer laser light as illumination light, and converts the illumination light from the light source 1 into a desired light beam shape. A beam shape converting means 2, an optical integrator 3 in which a plurality of cylindrical lenses and minute lenses are arranged two-dimensionally, and a switching means (not shown) which can be switched to an arbitrary aperture and formed by the optical integrator 3. A reticle 11 composed of a diaphragm member 4 disposed near the position of the secondary light source, a condenser lens 5 for condensing illumination light passing through the diaphragm member 4, a half mirror 6, and, for example, four variable blades. And a blind 7 arranged on a conjugate plane of the reticle 11 to arbitrarily determine an illumination range on the surface of the reticle 11. An imaging lens 8 for projecting the specified illumination light onto the surface of the reticle 11, a bending mirror 9 for reflecting the illumination light from the imaging lens 8 in the direction of the reticle 11, and a reticle 11 and a bending mirror 9; It has a correction optical system 10 that is disposed between the two and that absorbs illumination light by filling a gas mixture as described later.

The illuminance unevenness adjusting unit is provided on the stage 15 and an exposure monitor 17 for indirectly monitoring the illuminance on the surface of the wafer 13 by measuring a part of the illumination light reflected by the half mirror 6. An illuminance measuring device 16 for directly measuring the illuminance and the illuminance distribution on the surface of the wafer 13 by moving the stage 15 and bringing it on the irradiation surface, an illuminance measuring device 16 and an exposure monitor 17
And a correction optical system 10 based on the detection result of the illuminance unevenness detection circuit 18 to make the illuminance distribution on the surface of the wafer 13 uniform. And an exposure unevenness correction circuit 19 that adjusts the exposure unevenness.

The operation of reducing and projecting the pattern of the reticle 11 onto the surface of the wafer 13 using the stepper configured as described above will be described.

First, the illumination light emitted from the light source 1 is converted into a predetermined shape by the beam shape conversion means 2 and then directed to the optical integrator 3. At this time, a plurality of secondary light sources are formed near the exit surface. Illumination light from the secondary light source is condensed by a condenser lens 5 via an aperture member 4, passes through a half mirror 6, and passes through a blind 7.
After it is determined to have a predetermined shape, the light is reflected by the bending mirror 9 via the imaging lens 8 and enters the correction optical system 10.

Subsequently, the illumination light passing through the correction optical system 10 passes through the pattern of the reticle 11 and passes through the projection optical system 12.
Incident on. After passing through the projection optical system 12, the pattern is reduced to a predetermined size, projected onto the surface of the wafer 13, and exposed.

Here, illuminance unevenness of the illumination light may occur on the surface of the wafer 13. This illuminance non-uniformity is caused not only by various factors as described above (fixed to the device) but also by a change in the illumination state (for example, a change in the aperture member 4).
In addition, there is also a change due to aging. The correction optical system 10 is for correcting illuminance unevenness due to these factors. That is, the illuminance distribution on the surface of the wafer 13 calculated based on the information from the illuminance measuring device 16 and the exposure monitor 17 (the output of the exposure monitor 17 may be used as a reference when measuring the illuminance unevenness). Use
The exposure unevenness correction circuit 19 drives the correction optical system 10 to adjust the illuminance distribution to be uniform.

Hereinafter, the principle of illuminance distribution correction by the correction optical system 10 will be described with reference to FIG. FIG. 2 shows that a certain Ar
FIG. 9 is a characteristic diagram illustrating an example of a measurement result of a wavelength intensity distribution of F excimer laser light. In the figure, the solid line represents the wavelength intensity distribution when the optical path is filled with nitrogen, and the broken line represents the wavelength intensity distribution when 1.5 m in the optical path is filled with air. At a wavelength where there is no difference in intensity between the nitrogen atmosphere and the air, absorption by air hardly occurs, and conversely, for example, 193.3 nm
It can be seen that the absorption by air is large at a wavelength where the difference in intensity between the nitrogen atmosphere and the air is large as in the vicinity.
This difference in absorption is considered to be mostly due to oxygen.

Therefore, a wavelength within a range in which an absorption difference between oxygen and nitrogen occurs, specifically, a predetermined wavelength within a range of about 192 nm to 194 nm is selected to change the oxygen concentration (or air concentration) in the optical path. As a result, arbitrary light absorption can be obtained. That is, the light amount can be arbitrarily attenuated in the vicinity of the optical path terminal portion.

FIG. 3 shows a specific example of the correction optical system 10 utilizing this principle. Here, the tilt component of the illuminance non-uniformity (inclination non-uniformity) is corrected, and for simplicity, it is assumed that the correction optical system 10 is arranged near the surface of the reticle 11. In FIG. 3, the correction optical system 10 is partitioned into two rooms (closed spaces) 10a and 10b by light transmitting members 10c, 10d and 10e such as a parallel flat plate made of quartz, for example.
The room 10a is provided with ventilation holes 31a and 31b, and the room 10b is provided with ventilation holes 32a and 32b, and these ventilation holes are configured to independently control the ratio of the mixed gas component in each room. I have. The gas mixture is composed of nitrogen and oxygen or nitrogen and air. Light transmitting member 1
0d has a planar structure inclined with respect to the incident surface of the incident illumination light La, Lb, Lc as shown in the figure. By controlling the oxygen concentration in each of the rooms 10a and 10b, the illuminance distribution on the irradiated surface is corrected.

Here, for the ArF excimer laser light of the light source 1, a wavelength having a slight absorption to oxygen is selected. In the case of a wavelength at which absorption such as oxygen and clean air does not occur at all, it is not possible to correct illuminance unevenness as shown in the present embodiment.

Normally, when the illuminance distribution is not corrected, the two rooms 10a and 10b shown in FIG. 3 are filled with nitrogen. Now, it is assumed that the illuminance distribution on the front entrance surface (upper side in the figure) of the correction optical system 10 is flat (no inclination unevenness) as shown in FIG. At this time, the rooms 10a, 10
When b is also filled with nitrogen, light absorption does not occur, so that the illuminance distribution shape on the light exit surface of the correction optical system 10 remains flat as shown in FIG. Even if slight light absorption occurs due to nitrogen, the illumination light La, Lb,
Since the absorptance is the same for the illumination light of Lc, the distribution shape remains flat.

Now, the nitrogen in the room 10b is partially replaced with oxygen (or air). Then, light absorption occurs when the illumination light passes through the room 10b. The distance of the illumination light La, Lb, Lc when passing through the room 10b is La <Lb <Lc
Therefore, there is a difference between the amounts absorbed, and the illuminance distribution on the light exit surface of the correction optical system 10 is a distribution falling downward to the right as shown in FIG. This inclination depends on the oxygen concentration in the room 10b.

FIG. 4D is a characteristic diagram showing an illuminance distribution when the oxygen concentration in the room 10a is increased while the room 10b is filled with nitrogen. Thus, room 10
By appropriately controlling the oxygen concentration of at least one of a and 10b, it is possible to arbitrarily change the inclination unevenness on the light emitting surface.

By utilizing such a property obtained by providing the correction optical system 10, the wafer 13
When the illuminance distribution is not uniform on the surface of FIG.
When the distribution is as shown in FIG. 4C, by performing the adjustment as shown in FIG. 4D, the non-uniform illuminance distribution is canceled and a uniform distribution as shown in FIG. 4A is achieved. become. Of course, in the case as shown in FIG.
The following adjustment may be performed.

In this embodiment, the light transmitting member 10d that partitions the correction optical system 10 into two rooms (closed spaces) is inclined in a direction parallel to the plane of FIG. 3, but in a direction perpendicular to the plane of FIG. Illuminance unevenness in that direction. The direction in which the light transmitting member 10d is inclined is arbitrary,
For example, the tilt direction may be arbitrarily rotated to correct the illuminance unevenness in that direction. Needless to say, it is also preferable to arrange two or more correction optical systems as shown in FIG. 3 and independently perform tilt unevenness correction in a plurality of directions.

FIG. 5 shows another embodiment of the optical system for correcting illuminance unevenness. In the correction optical system 101 according to this another embodiment, the transmission member 101d that partitions the rooms 101a and 101b has a curved surface shape instead of a plane-parallel plate. Correction optical system 101
The inner room 101a has a center portion that is thinner in the optical axis direction and a peripheral portion that is thicker. In contrast, room 1
01b has a thicker central portion and a thinner peripheral portion.
The room 101a has ventilation holes 102a and 102b,
Vent holes 103a and 103b are provided in 01b, respectively, and the ratio of the mixed gas component is controlled by these vent holes.

FIG. 6 shows the illuminance distribution when the oxygen concentration of each of the rooms 101a and 101b is changed in the correction optical system 101.

Now, the first incident surface (upper surface) of the correction optical system 101
It is assumed that the illuminance distribution is flat as shown in FIG. At this time, if each of the rooms 101a and 101b is filled with nitrogen, light absorption does not occur.
The illuminance distribution on the light exit surface of the correction optical system 101 is shown in FIG.
Remains flat. Even if light absorption occurs due to nitrogen, the distribution shape remains flat because the absorptance is the same for the illumination lights Ld, Le, and Lf.

Here, the nitrogen in the room 101b is partially replaced with oxygen (or air). Then, light absorption occurs when the illumination light passes through the room 101b. Room 101
b, the distance between the illumination light Ld, Le, and Lf is longer in the central illumination light Le than in the peripheral illumination light Ld and Lf, so that there is a difference in the absorption amount between the illumination light Le and the correction optical system. The illuminance distribution on the light exit surface 101 is a distribution having a low center as shown in FIG. The absorptance of this illumination light is room 101
It depends on the oxygen concentration in b.

FIG. 6D is a characteristic diagram showing the illuminance distribution when the oxygen concentration in the room 101a is increased while the room 101b is filled with nitrogen. As described above, by appropriately controlling the oxygen concentration in each of the rooms 101a and 101b, the ratio of the peripheral illuminance on the light exit surface (to the central illuminance) can be changed.

As described above, in the stepper of the first embodiment, when the illumination light emitted from the light source 1 passes through the correction optical system 10 (101), The illumination light is absorbed by the oxygen (or air), and the illuminance is reduced. Here, the correction optical system 10
(101) is configured so that the optical path length of the illumination light differs depending on the position where the illumination light passes, that is, the absorption rate by oxygen differs.
The illumination light passing through 1) partially illuminates the surface of the wafer 13 which is the surface to be irradiated, with distributions having different illuminances. In the present embodiment, the correction optical system 10 (1
01), the illuminance unevenness of the irradiated surface is offset by adjusting the illuminance distribution on the irradiated surface by changing the oxygen concentration in
An extremely uniform illuminance distribution can be obtained on the irradiated surface. Therefore, according to this stepper, exposure can be performed with an extremely uniform illuminance distribution, which contributes to high-precision fine processing.

In the present embodiment, it is desirable that the replacement of the atmosphere component is performed for a material having a small difference in the refractive index. For example, the replacement of the atmosphere component with vacuum, nitrogen, air, oxygen, argon, helium, hydrogen or the like is preferable. However, this is not the case for an optical system in which the difference in refractive index does not matter.
For example, replacement of water with air is possible.

In this embodiment, the light source 1 is Ar
Although an F excimer laser and oxygen are used as an example of an absorbing substance, for example, an F ₂ laser may be used as a light source and an arbitrary absorbing gas may be selected. Of course, the control may be performed by changing only the humidity of the atmosphere component.

Here, some modifications of the first embodiment will be described. The same members as those constituting the stepper of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

First Modification First, a first modification will be described. Here, instead of providing the correction optical system 10 (101) as shown in FIGS. 3 and 5, in the lens barrel of the condenser lens 5,
The oxygen (or air) existing in the enclosed space between the lenses is replaced. That is, as shown in FIG. 7, in the lenses 5a, 5b, 5c constituting the condenser lens 5, a closed space 5 is provided between the lenses 5a, 5b and between the lenses 5b, 5c.
d, 5e are formed. Due to the shape of the lenses 5a, 5b, 5c, the distance that the light flux from the light source 1 passes through the closed spaces 5d, 5e varies depending on the passing position. In the first modification, by utilizing this property, the ventilation holes 41a, 41b and 42a, 42b provided in the closed spaces 5d, 5e are used.
By adjusting the oxygen (or air) concentration in the closed spaces 5d and 5e, the illuminance distribution on the irradiated surface is uniformly adjusted as in the case where the correction optical system 10 is provided.

In order to achieve a uniform illuminance distribution, it is most effective to provide a correction optical system near the surface to be illuminated as shown in FIGS. If there is a difference in the absorption of the illumination light between the light beams incident on the point, a difference occurs in the illuminance distribution, so that any optical system from the light source 1 to the surface to be irradiated can be replaced (the oxygen concentration and the like can be controlled). Then, the illuminance distribution may be corrected. Of course, it is also preferable to perform the correction using a plurality of optical systems.

-Modification 2 Next, Modification 2 will be described. Here, in addition to the correction optical system 10 (101) as shown in FIGS.
The illuminance of light from the light source 1 is controlled.

Conventionally, when adjusting the amount of light from the light source 1, as shown in FIG.
The turret 21 in which the D filters 21a to 21h are provided in an arc shape is arranged, and the turret 21 is rotated to select an ND filter corresponding to a desired light amount, thereby controlling the light amount. However, in this case,
The control of the light quantity depends on the number of ND filters, and inevitably only a discontinuous control can be performed.

In the second modification, as shown in FIG. 9, the light amount is controlled by changing the oxygen concentration using a chamber 22 in which the oxygen concentration is variable. This chamber 22 is provided, for example, between the light source 1 and the beam shape converting means 2 in FIG. Illumination light from the light source 1 passes through the chamber 22 which is shielded from the outside air, and is directed to the surface of the wafer 13 via the above-described optical system. The chamber 22 is shielded from outside air by parallel plane plates 22a and 22c made of a material through which incident light is sufficiently transmitted, and controls the oxygen concentration in the inside 22b of the chamber 22 by ventilation holes 51a and 51b.

By using this chamber 22,
Light absorption can be generated by controlling the oxygen concentration, and the intensity of the light beam emitted from the inside 22c can be controlled. The chamber 22 includes an exposure unevenness correction circuit 1 similar to the correction optical system 10.
9, the illuminance measuring device 16 and the exposure amount monitor 1
The illuminance is monitored at 7 and the chamber 22 is
The oxygen concentration in the interior 22b is controlled. Therefore, the use of the chamber 22 in combination with the correction optical system 10 enables finer illuminance distribution control. Of course, if necessary, the light quantity can be controlled by providing the chamber 22 alone without using the correction optical system 10 together.

(Second Embodiment) Subsequently, the second embodiment of the present invention
An embodiment will be described. In the first embodiment, the illuminance unevenness is corrected by changing the ratio of oxygen or the like without changing the wavelength of the light source. However, in the second embodiment, the ratio of oxygen or the like in the correction optical system is set to a fixed ratio. The case where the illuminance distribution is changed by changing the wavelength of the light source will be exemplified. In addition,
The same members as those constituting the stepper of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

FIG. 10 is a schematic diagram showing a main configuration of a stepper according to the second embodiment. This stepper has substantially the same configuration as that of the first embodiment shown in FIG.
In the second embodiment, the exposure unevenness correction circuit 19 is also connected to the light source 1.

As shown in FIG. 2, the absorptivity of light from the light source 1 to oxygen (air) is slightly different at each wavelength. For example, at a certain wavelength, the absorptivity for air and nitrogen does not change at all, and at a certain wavelength, there is a great difference between them. By changing the wavelength between these, the absorptivity can be continuously changed.

Accordingly, for example, oxygen is introduced into the room 10a of the correction optical system 10 shown in FIG.
With the room 10b filled with nitrogen, the illuminance distribution can be continuously changed by changing the wavelength of the light source 1 within a range of, for example, 192 nm to 194 nm. By utilizing this property and controlling the wavelength of the illumination light from the light source 1 by the exposure unevenness correction circuit 19, the illuminance distribution of the illumination light on the surface of the wafer 13 is made uniform as in the first embodiment. Can be adjusted.

In the stepper according to the second embodiment, when the illumination light emitted from the light source 1 passes through the correction optical system 10, the correction optical system 10
The illumination light is absorbed by oxygen (or air) in the interior, and the illuminance is reduced. Here, since the correction optical system 10 is configured so that the optical path length of the illumination light differs depending on the position where the illumination light passes, that is, the absorption rate of the illumination light differs, the illumination passing through the correction optical system 10 The light partially illuminates the surface of the wafer 13, which is the surface to be irradiated, with distributions having different illuminances. In the present embodiment, by utilizing this property, the light source 1 is maintained while the oxygen concentration in the correction optical system 10 is maintained at a predetermined constant value.
By adjusting the illuminance distribution on the illuminated surface by changing the wavelength of, the illuminance unevenness of the illuminated surface is offset,
An extremely uniform illuminance distribution can be obtained on the irradiated surface. Therefore, according to this stepper, exposure can be performed with an extremely uniform illuminance distribution, which contributes to high-precision fine processing.

The present invention is not limited to the above-described first and second embodiments and various modifications. For example,
In consideration of both the first and second embodiments, the correction optical system 1
A composite method in which the wavelength of the light from the light source 1 is also changed while changing the ratio of the oxygen concentration within 0 (for convenience, FIG.
Shows a configuration that can cope with this. ). According to this method, more precise illuminance distribution control is possible, so that a more accurate and uniform illuminance distribution is obtained, and a high-precision stepper that can be sufficiently applied to further fine processing is realized. .

The method for controlling the illuminance distribution on the surface to be illuminated and achieving a uniform illumination distribution has been described above. However, in the case of a scanning exposure apparatus which is becoming mainstream at present, it is not always necessary to make the entire surface to be irradiated uniform. When the present invention is applied to a scanning type exposure apparatus, it is sufficient that there is no exposure unevenness in the result of the scanning exposure, so that unevenness in the scanning direction can be ignored to some extent. Further, the integrated light amount in the scanning direction only needs to be the same at each position (each position in the direction orthogonal to the scanning). Therefore, it is sufficient to make the illuminance distribution variable only in the direction orthogonal to the scanning direction.

Next, an example of a method of manufacturing a semiconductor device (semiconductor device) using the projection exposure apparatus described with reference to FIGS. 1 and 10 will be described.

FIG. 11 shows a semiconductor device (IC or LSI).
2 shows a flow of a manufacturing process of a semiconductor chip such as a liquid crystal panel or a CCD. First, in step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design. On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4 (wafer process) is referred to as a pre-process, and actual circuits are formed on the wafer by photolithography using the mask and wafer prepared as described above. The next step 5 (assembly) is called a post-process, and step 4
This is a process of forming a semiconductor chip using the wafer produced by the above, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 12 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. Step 14 (ion implantation) implants ions into the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the projection exposure apparatus described above to expose the circuit pattern of the mask onto the wafer by printing. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), the unnecessary resist after etching is removed. By repeating these steps,
Multiple circuit patterns are formed on the wafer.

By using this manufacturing method, a highly integrated semiconductor device, which has conventionally been difficult to manufacture, can be manufactured easily and reliably.

[0093]

According to the illuminating device of the present invention, it is possible to achieve a uniform illuminance distribution while suppressing the illuminance unevenness on the surface to be illuminated without decentering the optical system.

When a projection exposure apparatus is constructed using this illumination apparatus, exposure can be performed with an extremely uniform illuminance distribution, and the demand for finer processing with higher precision in recent years can be sufficiently satisfied. High reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a main configuration of a stepper according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram obtained by measuring absorption by air at each wavelength of an ArF excimer laser.

FIG. 3 is a schematic sectional view illustrating a configuration example of a correction optical system.

FIG. 4 is a characteristic diagram illustrating an illuminance distribution when illuminance is adjusted using the correction optical system of FIG. 3;

FIG. 5 is a schematic sectional view showing another configuration example of the correction optical system.

FIG. 6 is a characteristic diagram illustrating an illuminance distribution when illuminance is adjusted using the correction optical system of FIG. 5;

FIG. 7 is a schematic cross-sectional view showing an example in which the present invention is applied to a lens barrel of a condenser lens in Modification Example 1 of the first embodiment.

FIG. 8 is a schematic view showing a conventional means for changing the amount of light incident on a stepper.

FIG. 9 is a schematic cross-sectional view showing a means for changing the amount of light incident on a stepper in Modification 2 of the first embodiment.

FIG. 10 is a schematic diagram illustrating a main configuration of a stepper according to a second embodiment of the present invention.

FIG. 11 is a flowchart showing a manufacturing process of a semiconductor device using the stepper according to the present invention.

FIG. 12 is a flowchart showing the wafer process in the step of FIG. 11 in further detail;

FIG. 13 is a schematic view showing a main configuration of a conventional stepper.

[Explanation of symbols]

 Reference Signs List 1 light source 2 beam shape conversion means 3 optical integrator 4 aperture member 5 condenser lens 6 half mirror 7 blind 8 imaging lens 9 bending mirror 10, 101 correction optical system 11 reticle 12 projection optical system 13 wafer 14 wafer chuck 15 wafer stage 16 illumination Measuring instrument 17 Exposure monitor 18 Illumination unevenness detection circuit 19 Exposure unevenness correction circuit 20 Illumination device

Claims (33)

[Claims] 1. An illumination device for irradiating illumination light onto a surface to be illuminated, wherein the illumination device has a closed space having an optical path length that differs depending on a position through which the illumination light passes, and a state of a substance constituting a fluid in the closed space. The illumination device adjusts the illuminance distribution on the surface to be illuminated by changing the illumination intensity. 2. A device for obtaining illuminance distribution information on the surface to be illuminated, and based on the illuminance distribution information obtained by the means, determines a state of a substance constituting a fluid in the closed space. The lighting device according to claim 1, wherein the lighting device is changed. 3. The lighting device according to claim 1, wherein the fluid in the closed space is a gas having a property of absorbing the illumination light having a predetermined wavelength. 4. The method according to claim 1, wherein a plurality of the closed spaces are provided, and a state of a substance constituting a fluid in each of the closed spaces can be independently changed. The lighting device according to the above. 5. An illumination device for irradiating illumination light onto a surface to be illuminated, wherein the illuminance distribution on the surface to be illuminated is adjusted by changing the wavelength of the illumination light. 6. Obtaining illuminance distribution information on the surface to be illuminated,
The illumination device according to claim 5, wherein the illuminance distribution on the irradiation surface is adjusted to a desired state based on the illuminance distribution information. 7. An illuminating device that irradiates illumination light onto a surface to be illuminated, wherein an illuminance distribution on the surface to be illuminated is adjusted by changing a state of a fluid existing in an optical path of the illumination light. Lighting equipment. 8. Obtaining illuminance distribution information on the surface to be illuminated,
The lighting device according to claim 7, wherein the illuminance distribution on the irradiated surface is adjusted to a desired state based on the illuminance distribution information. 9. The lighting device according to claim 7, wherein the fluid is a gas having a property of absorbing the illumination light having a predetermined wavelength. 10. A projection exposure apparatus, comprising: the illumination device according to claim 1; wherein the projection exposure apparatus performs projection by projecting a predetermined pattern onto a wafer surface as the irradiation surface. 11. An illumination device for directing light from a light source to a surface to be illuminated through an optical system, wherein at least a part of the optical systems in the optical system is based on illuminance or illuminance distribution information on the surface to be illuminated. A lighting device for controlling the ratio of the atmospheric components. 12. The lighting device according to claim 11, wherein the ratio of the atmosphere component is controlled by controlling an oxygen concentration. 13. The lighting device according to claim 11, wherein the light source includes light having a wavelength in a range of 192 nm to 194 nm. 14. The illuminating device according to claim 11, wherein the light source is an ArF excimer laser. 15. The lighting device according to claim 11, wherein a wavelength of said light source is variable. 16. A projection exposure apparatus, comprising: the illumination device according to claim 11; and projecting a predetermined pattern onto the wafer surface, which is the surface to be irradiated, to perform exposure. 17. The projection exposure apparatus according to claim 16, wherein an oxygen concentration in at least a part of the optical system is controlled based on illuminance distribution information and exposure amount information on the wafer surface. 18. A hermetically sealed light source that emits illumination light, and a fluid that has a property of absorbing the illumination light is sealed in at least the interior of the light source so that the absorption rate of the illumination light varies depending on the position through which the illumination light passes. An optical system for directing the illumination light to the surface to be illuminated through the closed space, and adjusting the illuminance distribution on the surface to be illuminated using the difference in the absorptance of the illumination light. A lighting device, comprising: 19. The illuminating device according to claim 18, wherein the illuminance distribution on the illuminated surface is adjusted by changing a state of a substance constituting the fluid in the closed space. 20. The illumination device according to claim 18, wherein the illuminance distribution on the illuminated surface is adjusted by changing a wavelength of the illumination light. 21. The optical system, comprising: a lens group for directing the illumination light to a surface to be illuminated; and a correction optical system having the closed space and arranged independently of the lens group. Claims 18 to
21. The lighting device according to any one of 20. 22. The optical system, comprising: a lens group for directing the illumination light to the surface to be illuminated; wherein the closed space is formed between predetermined lenses constituting the lens group. 21. The lighting device according to any one of items 18 to 20. 23. Detecting means for detecting illuminance distribution information on the surface to be illuminated, and controlling the optical system according to the illuminance distribution information from the detecting means to configure the fluid in the closed space. 20. The lighting device according to claim 19, further comprising: a correction unit that changes a state of the substance to be changed. 24. A detecting means for detecting illuminance distribution information on the surface to be illuminated, and a correcting means for controlling the light source to change the wavelength of the illuminating light according to the illuminance distribution information from the detecting means. 21. The lighting device according to claim 20, further comprising: 25. The fluid according to claim 18, wherein the fluid is a mixed gas containing oxygen, and the illuminance distribution on the irradiated surface is adjusted by changing an oxygen concentration.
The lighting device according to claim 1. 26. The method according to claim 18, wherein a plurality of the closed spaces are provided, and a state of a substance constituting a fluid in each of the closed spaces can be independently changed. The lighting device according to the above. 27. A light source which emits illumination light, and a hermetically sealed structure wherein at least a gas having a property of absorbing the illumination light is sealed therein so that the absorptance of the illumination light varies depending on a position through which the illumination light passes. An optical system having a space and directing the illumination light to the surface to be illuminated through the enclosed space; a detecting unit for detecting illuminance distribution information on the surface to be illuminated; and the illuminance distribution information from the detecting unit. And a correcting unit that changes the concentration of the gas in the closed space in accordance with the correction value and adjusts the illuminance distribution on the surface to be irradiated. 28. A light source which emits illumination light, and a hermetically sealed structure wherein at least a gas having a property of absorbing the illumination light is sealed therein so that the absorptance of the illumination light varies depending on the position through which the illumination light passes. An optical system having a space and directing the illumination light to the surface to be illuminated through the enclosed space; a detecting unit for detecting illuminance distribution information on the surface to be illuminated; and the illuminance distribution information from the detecting unit. And a correcting means for controlling the light source to change the wavelength of the illuminating light in accordance with the illuminant and adjusting the illuminance distribution on the illuminated surface. 29. A light source for emitting illuminating light, and a hermetic seal, wherein at least a gas having a property of absorbing the illuminating light is sealed therein so that the absorptance of the illuminating light varies depending on a position through which the illuminating light passes. An optical system that has a space and directs the illumination light to the surface to be illuminated through the enclosed space; a detection unit that detects illuminance distribution information on the surface to be illuminated; and the illuminance distribution information from the detection unit. Correction means for changing the concentration of the gas in the enclosed space, controlling the light source to change the wavelength of the illumination light, and adjusting the illuminance distribution on the irradiated surface. A lighting device characterized by the above-mentioned. 30. The airtight system according to claim 27, wherein the closed space is filled with a plurality of gases including a gas having a property of absorbing the illumination light.
30. The lighting device according to any one of -29. 31. The method according to claim 27, wherein a plurality of the closed spaces are provided, and a state of a substance constituting a fluid in each of the closed spaces can be independently changed. The lighting device according to the above. 32. A projection exposure apparatus for performing exposure of a predetermined pattern on a wafer surface, which is a surface to be irradiated, wherein the reticle on which a pattern similar to the predetermined pattern is formed is irradiated with illumination light. 1
13. A projection exposure apparatus, comprising: the illumination device according to item 1 .; and a projection optical system that projects the similar pattern of the reticle onto the wafer surface so as to become the predetermined pattern. 33. A step of applying a photosensitive material to a wafer surface, and using the projection exposure apparatus according to claim 10, wherein the photosensitive material is applied to the wafer surface. And a step of developing the photosensitive material that has been exposed to the predetermined pattern.