JPH10270326A - Exposure light source, exposure method and exposure apparatus - Google Patents

Abstract

[PROBLEMS] To provide an exposure light source capable of efficiently generating ultraviolet light having a wavelength of about 193 nm by wavelength conversion, instead of an ArF excimer laser. SOLUTION: A green component laser beam L1 having a wavelength of 511 nm extracted from an output mirror 31a of a copper laser oscillator 1 is provided.
After passing through the copper laser amplifier 2 as the laser beam L2 whose beam diameter has been expanded by the beam diameter converter 3a, the laser light becomes excitation light for the dye laser oscillator 6 and the dye laser amplifier 7 via the dichroic mirror 4b. The dye laser oscillator 6 oscillates a laser beam L11 having a wavelength of 578 nm, is amplified by the dye laser amplifier 7, and is extracted as a laser beam L12.
Further, a laser beam L13 whose beam diameter is expanded by the beam diameter converter 3b is reflected by the dichroic mirror 4a, passes through the copper laser amplifier 2, and is amplified by the wavelength 5
Nonlinear optical crystal 11 as 78 nm laser light L15
a, exposure light L3 having a wavelength of 193 nm
It becomes 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure light source, an exposure technique, and a semiconductor device manufacturing technique, and more particularly to a technique effective when applied to a photolithography technique using laser light in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art There are various types of performance required for an exposure apparatus (generally called a stepper) used for photolithography, such as resolution, alignment accuracy, processing capability, and apparatus reliability. Among them, the resolution R directly leading to the miniaturization of the pattern is R = k · λ / NA
Since (k: constant, λ: exposure wavelength, NA: numerical aperture of the projection lens), an exposure light source having an exposure wavelength λ as short as possible is preferable in order to obtain good resolution.

In a conventional general exposure apparatus, a g-line (wavelength: 436 nm) or an i-line (wavelength: 365 n) of a mercury lamp is mainly used.
m) has been used as an exposure light source, but a KrF excimer laser having a wavelength of 248 nm has been used in order to realize a finer processing line width. As an exposure light source for performing finer processing, a wavelength of 193 is used.
The use of an nm ArF excimer laser is being studied.
Regarding this, for example, the Laser Society of Japan Academic Lecture 1996, 16th Annual Conference,
VII4 (pages 96 to 99).

[0004]

A technical problem when using an ArF excimer laser as an exposure light source is that if the band is not narrowed, the wavelength width is 50 to 100 pm, and even if the band is narrowed, the wavelength is about 10 pm. The point is that it is difficult to generate exposure light having a narrower bandwidth than a wavelength width of 1 pm required for a stepper used as an exposure lens. That is, since the wavelength of about 200 nm or less including the wavelength of the ArF excimer laser is in the vacuum ultraviolet region, the absorption rate of many optical materials generally becomes considerably high. Therefore, the laser light in the oscillator is absorbed by the band-narrowing element itself, and a sufficient laser output cannot be obtained, or the band-narrowing element is easily deteriorated due to the absorption of the laser light. Has become a technical issue. Regarding this, for example, the monthly Semiconductor World 19
This is described in November 1995, pp. 16-17.

Another technical problem is that, in a conventional apparatus using an excimer laser as an exposure light source, the peak power of the laser beam is high, so that the lens material of the stepper is easily damaged. Therefore, in order to increase the average output without increasing the peak power, that is, without increasing the energy of the laser pulse, it is necessary to increase the number of pulse repetitions. However, an excimer laser generally has a limit of a repetition rate of about 1 kHz.

An object of the present invention is to provide an exposure light source capable of generating exposure light in a vacuum ultraviolet region having a sufficiently narrow band, instead of an ArF excimer laser.

Another object of the present invention is to provide an exposure light source capable of efficiently generating vacuum ultraviolet light having a wavelength of about 193 nm, which is the same as that of an ArF excimer laser.

Another object of the present invention is to provide an exposure technique which can extend the life of an exposure optical system and use the apparatus for a long period of time.

Another object of the present invention is to provide an exposure technique capable of realizing cost reduction and improvement in throughput in an exposure step.

Another object of the present invention is to provide a semiconductor device manufacturing technique capable of efficiently manufacturing a semiconductor device having a design rule of a wavelength in a vacuum ultraviolet region.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0012]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

[0013] In the exposure light source according to the present invention, a copper laser;
A dye laser, at least two nonlinear optical crystals, operating the dye laser using the laser light extracted from the copper laser as excitation light, and converting the laser light extracted from the dye laser into at least two nonlinear optical crystals. Exposure light is obtained by passing through a crystal. The copper laser is a gas laser using energy transition between excited levels of copper atoms, and includes a copper vapor laser, a copper bromide laser, and the like.

In order to particularly efficiently obtain exposure light having a wavelength of about 193 nm, laser light extracted from a dye laser is passed through a discharge tube constituting a copper laser, and then passed through a nonlinear optical crystal to be used as exposure light. Output. The copper laser may be either a copper laser oscillator or a copper laser amplifier, and the dye laser may be either a dye laser oscillator or a dye laser amplifier.

In general, a dye laser excited by a copper laser depends on a dye to be used.
It is known that laser light can be efficiently oscillated at a wavelength of 570 to 600 nm by using such a dye. Therefore, as a third harmonic generated by passing the nonlinear optical crystal twice, a wavelength 19 covering the wavelength of the ArF excimer laser is used.
Ultraviolet light of 0 nm to 200 nm is obtained. In addition, since a copper laser generally operates at a repetition rate of 5 to 6 kHz,
With the same average output as compared with a normal excimer laser, the peak power of the pulse can be reduced by one digit as compared with the excimer laser.

In order to generate exposure light having a narrow band, it is sufficient to use a dye laser having a wavelength of 570 to 600 nm. That is, the band is narrowed in the visible region. No damage will be taken.

Although the copper laser oscillates most strongly at a wavelength of about 511 nm, there is also a second oscillation line at a wavelength of about 578 nm, which corresponds to the oscillation wavelength band of a normal dye laser excited at a wavelength of about 511 nm. included. Therefore, since the dye laser can oscillate at a wavelength of 578 nm, which coincides with the second oscillation line of the copper laser, the laser light of the dye laser having a wavelength of 578 nm is passed through the discharge tube of the copper laser, so that the laser of the dye laser is emitted. Light will be subject to amplification.

Further, the third harmonic obtained by passing the laser light having a wavelength of 578 nm through two nonlinear optical crystals and performing wavelength conversion twice has a wavelength of about 193 nm.
Ultraviolet light having substantially the same wavelength as that of the F excimer laser can be obtained.
Generally, the oscillation wavelength of the copper laser is about 5 wavelengths.
11 nm may be referred to as a green component and a wavelength of about 578 nm may be referred to as a yellow component, and it is known that the ratio of laser output is approximately 6 to 4.

Since the fundamental wave to be wavelength-converted is oscillated by the dye laser, it is easy to oscillate with a small beam diameter and oscillate in a single mode. That is, a fundamental wave can be generated as a high-quality beam having a very small divergence angle.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a conceptual diagram showing an example of the configuration of an exposure light source according to a first embodiment of the present invention.

The exposure light source of this embodiment is roughly divided into a copper laser oscillator 1, a copper laser amplifier 2, a dye laser oscillator 6, a plurality of nonlinear optical crystals 11a and a nonlinear optical crystal 11b for wavelength conversion. In the case of the present embodiment, as the nonlinear optical crystals 11a and 11b, for example, a β-BaB ₂ O ₄ crystal can be used.

The copper laser oscillator 1 includes a discharge tube 1a, an output mirror 31a, and a total reflection mirror 33a. Wavelength 5 extracted from output mirror 31a of copper laser oscillator 1
The 11 nm green component laser light L1 travels to the copper laser amplifier 2, which is a copper laser constituting the present invention. Although a general copper laser oscillator contains both a green component and a yellow component, the output mirror 3 of the copper laser oscillator 1 of the present embodiment is included.
In 1a, almost 100% of the yellow component is reflected, so that almost 100% of the laser beam L1 is a green component. The beam diameter of the laser beam L1 is expanded (referred to as laser beam L2) by a beam diameter converter 3a including two lenses, and impinges on a dichroic mirror 4a. Since the dichroic mirror 4a has a transmittance of almost 100% at a wavelength of 511 nm and a reflectance of almost 100% at a wavelength of 578 nm, the laser light L2 of the green component passes through the dichroic mirror 4a with almost no loss and passes through the copper. It is possible to proceed to the laser amplifier 2.
As a result, the laser light L2 passes through the inside of the discharge tube 2b of the copper laser amplifier 2 and is subjected to an amplifying action, thereby increasing the laser output. The amplified green component laser beam L3 impinges on the dichroic mirror 4b.

The dichroic mirror 4b has a wavelength of 511n.
m has a reflectance of almost 100% at a wavelength of 578 n
Since the transmittance at m is almost 100%, the laser light L3 of the green component is reflected by the dichroic mirror 4b and proceeds like the laser light L4. The laser light L4 is reflected by the mirror 5a and used as excitation light for the dye laser oscillator 6 and the dye laser amplifier 7. That is, the laser beam L4 is supplied with 70% and 30% of the power of the laser beam L5 and the laser beam L6 to the dye laser amplifier 7 and the dye laser oscillator 6, respectively, by the beam splitter 8a and the mirror 5b. As a result, a laser beam L11 having a wavelength of 578 nm oscillates from the dye laser oscillator 6, and the dye jet 9 constituting the dye laser amplifier 7 is formed.
Pass through a. The laser beam L5 of the green component from the copper laser is focused on the dye jet 9a by the lens 10. As a result, the laser beam L11 from the dye laser oscillator 6 is amplified and extracted as a laser beam L12. The laser beam L12 is reflected by the mirror 5c, and the beam diameter is enlarged to the same thickness as the laser beam L2 by the beam diameter converter 3b including two lenses (the laser beam L13).
And ), And hits the dichroic mirror 4a.

Since the dichroic mirror 4a has a high reflectance of almost 100% at the wavelength of 578 nm as described above, it is reflected here and becomes the laser beam L14, which is superimposed on the laser beam L2.

Therefore, it is generated by the dye laser oscillator 6 and
The laser light L12 (L1) amplified by the dye laser amplifier 7
3) passes through the inside of the discharge tube 2b of the copper laser amplifier 2. Since the wavelength of the laser light L12 (L13) coincides with the wavelength 578 nm of the yellow component of the copper laser, the discharge tube 2b
When passing through the inside, it is subject to amplification. As a result, wavelength 5
The 78 nm laser light is greatly amplified to a wavelength of 578 nm.
Passes through a dichroic mirror 4b having a transmittance of almost 100% (this is referred to as a laser beam L15), and the nonlinear optical crystal 11a located to the right in FIG.
And 11b.

As described above, in the present invention, the energy of the yellow component laser light that can be extracted from the copper laser amplifier 2 is added to the laser light L12 generated by the dye laser oscillator 6 and amplified by the dye laser amplifier 7. Therefore, even if there is only one stage of the dye laser amplifier 7, the wavelength 5
The laser light of the 78 nm dye laser can be greatly increased. In general, the output ratio of laser light of a green component and a yellow component that can be generated from a copper laser is about 60:40.
The laser output of the dye laser excited by the green component of the copper laser is generally about 40% of the green component output. Therefore, the laser output of the conventional copper laser-excited dye laser and the wavelength 57 obtained by the present invention can be obtained.
The output ratio with 8 nm is 60 × 0.40: 60 × 0.40 +
40 = 24: 64. That is, in the present invention, a laser output twice or more as compared with the conventional one can be obtained.

The laser light L15 having a wavelength of 578 nm passes through the nonlinear optical crystal 11a and is wavelength-converted to generate a laser light L20 in the ultraviolet region having a wavelength of 289 nm as the second harmonic.
However, the laser light L20 also includes a laser light L15 having a wavelength of 578 nm which has not been wavelength-converted by the nonlinear optical crystal 11a. This laser light L20 is incident on the nonlinear optical crystal 11b, and generates a third harmonic laser light L30 having a wavelength of 193 nm, which is a sum frequency of the second harmonic having a wavelength of 289 nm and an unconverted fundamental wave. This is the exposure light. Although the exposure light L30 is a pulsed laser beam, the pulse repetition rate is equal to the repetition rate of the copper laser oscillator 1, and here is 5 kHz which is the repetition rate of a normal copper laser.

Incidentally, the total reflection mirror 33 of the copper laser oscillator 1
As a characteristic of a, almost 100% at a wavelength of 511 nm
At a wavelength of 578 nm.
The transmittance is about 0%. The output mirror 31a has a total reflection of almost 100% at a wavelength of 578 nm. As a result, the yellow component having a wavelength of 578 nm oscillating in the copper laser oscillator 1 is extracted from the total reflection mirror 33a to the left in FIG. 1 as laser light L41. The laser beam L41 is reflected by the mirror 5d, and is reflected by the beam diameter converter 3
Through c, the beam diameter decreases (referred to as laser light L42), and the laser beam advances into the dye laser oscillator 6. A pinhole plate 12 is disposed between the two lenses constituting the beam diameter converter 3c.
Only the laser beam of high beam quality that advances through the minute hole of FIG. 1 proceeds to the dye laser oscillator 6.

Here, the dye laser oscillator 6 will be described with reference to FIG.
Will be described. In the dye laser oscillator 6, the output mirror 3
2a and the total reflection mirror 34 constitute a resonator, and a laser beam L6 of a green component from a copper laser as an excitation light source is supplied to a lens 10b with respect to a dye jet 9b as a flow of a dye solution as a laser medium. Collect light through. As a result, the dye solution, which is a laser medium, is excited to cause laser oscillation.

In the present embodiment, in the dye laser oscillator 6, as a result of the excitation light being focused on one point in the dye jet 9b, the oscillating laser light beam becomes narrow to about 0.3 mm. Incidentally, the Fresnel number F, which is a parameter that affects the oscillation mode of laser light, is proportional to the square of the beam diameter and inversely proportional to the cavity length. In addition, the smaller the Fresnel number, the lower the mode of oscillation. In the dye laser oscillator 6, since the beam diameter can be generally reduced to 1 mm or less, it is also a feature of the present invention that oscillation in a single mode is facilitated. That is, in the single mode, since the beam divergence angle is small, the efficiency of wavelength conversion by the nonlinear optical crystal increases.

On the other hand, in a general copper laser oscillator,
The resonator length is about 2 m, which is one digit larger than that of a normal dye laser oscillator, but the beam diameter is 30 digits to 50 mm, which is two digits larger. As a result, the Fresnel number increases by about 1000 times, and oscillation in a high-order multimode becomes easy. Therefore, if the wavelength of 578 nm oscillated from the copper laser oscillator is directly converted, the efficiency of the wavelength conversion is reduced due to the high-order multimode having a large beam divergence angle.

In this embodiment, the laser beam L41 (L42) having a wavelength of 578 nm from the copper laser oscillator 1 is used.
Goes into the dye laser oscillator 6, and the beam splitter 8b
Irradiates the dye jet 9b, which is a laser medium. Accordingly, the wavelength 57
The laser beam L41 (L42) having a wavelength of 8 nm is guided and oscillates at the same wavelength of 578 nm. This is a technique called injection locking. That is, since laser light is emitted from the dye laser oscillator 6 at a wavelength of 578 nm, in this embodiment, it is not necessary to use a diffraction grating as a wavelength selection element often used in ordinary dye laser oscillators. Thus, the structure of the dye laser oscillator 6 can be simplified and the cost can be reduced. Moreover, the oscillation wavelength is 578 nm
Is coincident with the oscillation line of the yellow component of the copper laser, but the oscillation line of the copper laser is related to the energy level of copper and is a physically determined value. Therefore, the wavelength of the 578 nm laser light oscillated by the dye laser oscillator 6 is stabilized and does not fluctuate. This is particularly effective when used as exposure light after wavelength conversion. That is, if the wavelength of the exposure light fluctuates, the focal position after passing through the exposure lens fluctuates, and the exposure pattern will be blurred.

In this embodiment, the etalon 1 is used to narrow the oscillation wavelength width from the dye laser oscillator 6.
3, whereby a laser beam L11 having a wavelength width narrowed to 1 pm or less can be obtained. However, even without using the etalon 13, the laser light L41 (L42) oscillated from the copper laser oscillator 1 can be obtained simply by causing the yellow laser light L42 from the copper laser oscillator 1 to enter the dye laser oscillator 6 and perform injection locking. Pm, which is equal to the wavelength width of the laser light, and the wavelength of the converted laser light is narrower than that of the conventional ArF excimer laser. The reason is that the wavelength width of the laser light oscillated from a copper laser oscillator is
This is because it is sufficiently narrower than the wavelength width of the F excimer laser.
That is, generally, the wavelength width of the excimer laser is particularly wide among other gas lasers during normal oscillation, and is 300 to 400 pm
This is because

As an exposure light source for generating vacuum ultraviolet light by wavelength conversion using a nonlinear optical crystal without using a conventional ArF excimer laser, for example, a laser light of a YAG laser oscillating at a wavelength of 1064 nm in a near infrared region is used. 5th harmonic, ie, 213 nm of wavelength, by wavelength conversion
Is generated. In this regard, for example,
1996 Laser Society Academic Lecture, 16th Annual Conference,
Preliminary lectures, 24pVII1 (pages 58 to 61)
Is described in.

However, since the wavelength of 213 nm is slightly longer than the wavelength of 193 nm of the ArF excimer laser, the technical problem is that the resolution of photolithography is inferior to that of the ArF excimer laser. Also, peripheral technologies for next-generation photolithography are being developed so that they can be used at a wavelength of 193 nm of an ArF excimer laser. For example, an exposure lens capable of obtaining a sharp image at a wavelength of 193 nm is under development.
Those which can obtain good sensitivity and transmittance with ultraviolet light of nm are under development. Therefore, with exposure light having a wavelength of 213 nm,
It was also a technical problem that the characteristics of the exposure lens and resist currently under development do not match. In contrast, the exposure light source of the present invention has a wavelength of 190 to 200 n including a wavelength of 193 nm.
Another major feature is that m vacuum ultraviolet light can be generated.

(Embodiment 2) Next, an exposure apparatus (stepper) using the exposure light source of the present invention will be described with reference to FIG. FIG. 3 is a conceptual diagram illustrating an example of the configuration of the exposure apparatus according to the first embodiment of the present invention.

The exposure apparatus 200 of this embodiment includes a stepper body 150 and the exposure light source 100 shown in FIG. Wavelength 19 extracted from exposure light source 100
The exposure light L30 of 3 nm is transmitted through the mirror 201a and the mirror 20
1b, the beam is expanded by a beam diameter converter 202, reflected by a mirror 201c, passes through a random phase plate 203, and the speckle noise of the exposure light is removed. The distribution is made uniform, and the reticle 20 passes through the condenser lens 205.
6 is irradiated. The laser beam emitted from the reticle 206 passes through a reduction projection lens 207 made of a quartz lens, and impinges on a wafer 209 placed on a wafer stage 208. Thereby, the pattern on the reticle 206 is reduced and projected on the wafer 209.

In this embodiment, since the repetition rate of the exposure light L30 is 5 kHz, the ArF of 500 to 600 Hz is used.
It is about 10 times higher than the excimer laser. Therefore, the peak power of the exposure light L30, which is a pulse laser light, is reduced by about 1 /
It was possible to reduce the reduction projection lens 207 to 10. In the present embodiment, the reduction projection lens 207 is a monochromatic lens made of quartz.

A which has been conventionally developed as a stepper light source
Since the wavelength width of the rF excimer laser is about 10 pm, it is difficult to use a monochromatic lens, and the use of an achromatic lens using fluorite and a stepper using a reflection optical system has been studied. On the other hand, since the wavelength width of the exposure light source can be easily reduced to 1 pm or less by a dye laser as in the present embodiment, a stepper of a refractive optical system using a monochromatic lens can be used.

As described above, in the present invention, a reduction projection lens 207 using a quartz lens can be used similarly to the conventional exposure apparatus. That is, since the reduction projection lens 207 that is technically deeply established can be used, a reduction projection lens having a sufficiently large aperture can also be used, and as a result, an exposure apparatus having a high processing capability can be realized. If a semiconductor integrated circuit is manufactured using the exposure apparatus, the manufacturing time is short and the throughput is improved, so that the cost of the semiconductor integrated circuit can be reduced.

(Embodiment 3) Next, an exposure light source according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a conceptual diagram showing an example of a configuration of an exposure light source 110 according to the second embodiment of the present invention.

The exposure light source 110 is roughly divided into a dye laser oscillator 24 which is a dye laser of a component of the present invention, and a copper laser oscillator 21 which is a copper laser of a component of the present invention. FIG. 4 shows that at least 2
Although the non-linear optical crystals are omitted, they may be arranged in series on the optical path of the laser beam L17, similarly to 11a and 11b shown in FIG. In the copper laser oscillator 21, a resonator is formed by the output mirror 31b and the total reflection mirror 33b so as to sandwich the discharge tube 22 for copper laser. Output mirror 31b
Has a transmittance of about 80% at a wavelength of 511 nm, and has a transmittance of 99% or more at a wavelength of 578 nm. The total reflection mirror 33b has a reflectance of almost 100% at a wavelength of 511 nm, and has a transmittance of 99% or more at a wavelength of 578 nm. Therefore, the copper laser oscillator 21 emits the green component laser light L having a wavelength of 511 nm.
Only 8 oscillates, is taken out of the output mirror 31b, advances to the left in FIG. 4, the beam diameter is reduced by the beam diameter converter 23, and advances into the dye laser oscillator 24.

On the other hand, in the dye laser oscillator 24, the output mirror 32b used has a transmittance of about 80% at a wavelength of 578 nm, and has a transmittance of 99% or more at a wavelength of 511 nm. Therefore, most of the green component laser light L8 generated by the copper laser oscillator 21 passes through the output mirror 32b, advances into the dye laser oscillator 24, and is used as excitation light. That is, the laser light L8 of the green component is applied to the dye jet 25 serving as a laser medium, and the dye laser oscillator 24 performs laser oscillation. In the present embodiment, the diffraction grating 27 that is a wavelength selector is used, and the wavelength 578 is used.
The laser oscillates in nm. That is, the wavelength of laser oscillation in the dye laser oscillator 24 can be controlled by controlling the installation angle of the diffraction grating 27 using an actuator (not shown). An etalon 26 for narrowing the wavelength width is also used.

The wavelength 57 oscillated by the dye laser oscillator 24
The 8 nm laser light L16 travels rightward in FIG. 4 from the output mirror 32b, passes through the beam diameter converter 23, expands its beam diameter, and travels toward the copper laser oscillator 21. On the other hand, the output mirror 31b and the total reflection mirror 33b used in the copper laser oscillator 21 have a transmittance of 99% or more at a wavelength of 578 nm. As a result, most of the laser light L16 passes through the copper laser oscillator 21. Since the laser beam L16 is tuned to the wavelength of the yellow component of the copper laser, the laser beam L16 is amplified when passing through the copper laser discharge tube 22, so that the amplified laser beam L17 having a wavelength of 578 nm is extracted. This laser light L17 is wavelength-converted twice by passing through two nonlinear optical crystals located on the optical path, as in the first embodiment shown in FIG.
Convert to 93 nm UV light.

In the second embodiment, the first embodiment shown in FIG.
The feature is that the configuration of the device is simplified as compared with the embodiment.

(Embodiment 4) Next, a second embodiment of a stepper using an exposure light source according to the present invention will be described with reference to FIG. FIG. 5 is a conceptual diagram showing an example of a configuration of an exposure apparatus according to the second embodiment of the present invention.

In this embodiment, the stepper body 300 uses the exposure light source 100 shown in FIG.

The exposure light L30 generated by the exposure light source 100 is reflected by the polygon mirror 301, passes through the fθ lens 302, and is irradiated on the reticle 303. The irradiation unit 304 of the exposure light L30 is indicated by oblique lines in the drawing. However, a mask 305 is arranged on the reticle 303, and only the exposure light L30 passing through a rectangular opening in the mask 305 is irradiated on the reticle 303.
The exposure light L30 applied to the reticle 303 is scanned (sub-scanned) in the Y direction by the polygon mirror 301.
Is irradiated in the entire Y direction. Note that a scan mirror may be used instead of the polygon mirror 301 in the present embodiment. However, as described below, it is more suitable to use a polygon mirror in the present invention.

FIGS. 6 and 7 are explanatory diagrams for explaining the scanning of the reticle 303 with the exposure light. In the present embodiment, as shown by the arrow shown in FIG. 6, the irradiation position of the exposure light applied to the reticle 303 moves little by little for each pulse. Since the exposure light is scanned by the polygon mirror 301, once the reticle 303 is scanned once in the Y direction as indicated by an arrow 312a, the reflection surface of the polygon mirror 301 changes. Returning, scanning is performed in the same direction as indicated by an arrow 312b. In FIG. 6, the exposure position for each pulse is slightly inclined from the Y direction because, as shown in FIG. 5, the reticle 303 is mounted on the movable portion 306 of the reticle stage 307 and the exposure is performed in the X direction during the exposure. (Main scanning). On the other hand, if the exposure light is scanned using a normal scan mirror other than the polygon mirror, as shown in FIG. 7, once the width of the reticle 303 has been scanned once as indicated by an arrow 313a. , The scanning direction is reversed. On the other hand, since the reticle 303 always moves in the X direction, the exposure location for each pulse is inclined in the opposite direction from the Y direction as shown by an arrow 313b. As a result, it becomes difficult to uniformly irradiate the reticle 303 with the exposure light L30. Therefore, in the present invention, the polygon mirror 301 is used in order to make the direction of movement of the exposure location for each pulse (the direction of sub-scanning) parallel to all the scans.

The image on the reticle 303 is reduced and projected on the wafer 309 by the reduction projection lens 308. Since the wafer 309 is placed on the movable part 310 of the wafer stage 311, it can reciprocate in the X direction (main scanning direction), like the reticle 303. Therefore, the scanning method is such that the reticle 303 and the wafer 309 can move in the X direction while being synchronized. Thereby, even if the intensity distribution of the exposure light irradiated on the wafer 309 in the X direction is non-uniform, the exposure light is averaged. Further, since the exposure light is scanned in the Y direction as in the present embodiment, a uniform exposure amount can be given also in the Y direction. Therefore, the entire surface of the exposure field on the wafer 309 can be uniformly exposed.

As described above, in the present embodiment, reticle 3
The exposure amount is made uniform by scanning not only 03 but also the exposure light L30 itself. The reason is as follows. In a conventional stepper using a KrF excimer laser, laser light extracted from the KrF excimer laser is passed through an illumination optical system or the like to make the intensity distribution uniform and enlarged, and then irradiates the entire reticle. However, in the present invention, the laser light in the vacuum ultraviolet region is used as the exposure light L30, but in that wavelength region, the absorptance of ordinary optical materials is high.
When the light passes through the illumination optical system, the laser output is greatly reduced. Therefore, in this embodiment, the exposure amount can be made uniform by scanning the exposure light L30 with the polygon mirror 301 without using the illumination optical system as described above.

As described above, in the present invention, the wafer 3
09, but also the exposure light L30 itself is scanned. This is possible because a copper laser is used and the number of repetitions is about ten times higher than that of a conventional excimer laser. is there.

That is, if the number of repetitions is not high, when the number of scans increases, the overlap of the irradiated portions due to adjacent scans decreases, and the exposure amount becomes uneven.

In the present invention, the use of a scanning stepper or the scanning of the exposure light L30 on the reticle 303 also has the effect of canceling out the average of the speckle noise of the exposure light L30. In particular, in the present invention, the ultraviolet light generated by the wavelength conversion is used as the exposure light L30, but the efficiency of the wavelength conversion is higher when the laser light is in a low-order mode such as a single mode. However, in the low-order mode, there is a problem that speckle noise increases.

(Embodiment 5) Next, referring to FIG. 8, an example of a method for manufacturing a semiconductor device using the exposure apparatus illustrated in FIG. 3 or FIG. 5 using the exposure light source of the present invention will be described. Will be described.

In FIG. 8, as an example of the step of performing photolithography, the silicon substrate 10 of the wafer 209 is used.
The case where a minute hole (contact hole 1002 a) is formed in an insulating film 1002 of silicon dioxide (SiO ₂ ) deposited (deposited) on the surface of No. 01 is shown in the order of steps.

In the photolithography process, first, as illustrated in FIG. 8A, a resist 1003 is applied to an insulating film 1002 deposited on a silicon substrate 1001.

Next, exposure is performed as shown in (2) (the number of arrows is the exposure light L30 in FIG. 2).
Is performed. That is, the exposure light L30 of the pattern of the reticle 206 (FIG. 2) is applied to the resist 100 on the wafer 209.
3 is irradiated. Here, the exposure light L is applied to a region corresponding to the position where the contact hole 1002a having the diameter ΔW is to be formed.
30 is not irradiated.

In this embodiment, the resist 1003
Is called a negative resist. When developed after exposure, only the portions not irradiated with the exposure light L30 are selectively dissolved and removed in the developing solution as shown in FIG. A hole 1003a having a diameter ΔW is formed.

Therefore, as shown in FIG. 8D, when etching is performed, the insulating film 1002 exposed through the hole 1003a formed by removing the resist 1003 is removed by etching.

Finally, as shown in FIG. 8 (5), by removing the resist by ashing or the like, the insulating film 1002 having the contact hole 1002a having a diameter ΔW remains on the silicon substrate 1001.

In the present embodiment, since the wavelength of the exposure light L30 is about 193 nm, a hole having a diameter of at least about 0.193 μm (such as a contact hole 1002a) or a width of 0.193 μm can be obtained even by ordinary exposure. Can be processed. Further, by using an ultra-high resolution technique such as a phase shift, it is possible to process a hole pattern or a line pattern having a diameter up to 0.11 μm, which is about 0.6 times the exposure wavelength. Therefore, the method of manufacturing a semiconductor device according to the present embodiment using the exposure apparatus
This is effective when performing fine processing such as 2a or gate processing with a design rule of about 0.2 μm or less.

The technical effects of each embodiment of the above-described exposure light source, exposure method, exposure apparatus, and semiconductor device manufacturing method of the present invention are as follows.

First, since the exposure light source of the present invention can suppress the deterioration of the band-narrowing element and the like, the exposure apparatus using the exposure light source of the present invention has a lower exposure intensity than the exposure apparatus using an ArF excimer laser. Running costs. In addition, since the band can be sufficiently narrowed, a monochromatic lens made of quartz can be used as the reduction projection lens as in the related art, so that the exposure apparatus can be configured at low cost.

Second, since the number of repetitions of the exposure light is about ten times higher than that of the conventional exposure light source using an excimer laser, the peak power of the exposure light pulse can be reduced to about 1/10 of the conventional one. The lens is less likely to be damaged.
Thereby, the power of the exposure light can be increased, and the throughput of the exposure apparatus is improved.

As described above, the first and second effects make it possible to reduce the cost of the exposure apparatus and improve the throughput, and it is possible to manufacture a semiconductor integrated circuit in a short time and at low cost. That is, an inexpensive semiconductor integrated circuit can be provided by using the exposure apparatus of the present invention.

Third, the exposure light source of the present invention has a wavelength of about 19
Since exposure light of 3 nm can be obtained, photolithography peripheral technologies such as an exposure lens and a resist under development can be directly applied assuming use of an ArF excimer laser.

Fourth, in the copper laser used as the exposure light source of the present invention, the energy of the yellow component, which has not been generally used conventionally, can be effectively used. As a result, the efficiency can be improved about twice as compared with the case where a conventional general copper laser-excited dye laser is used.

Fifth, since the fundamental wave is oscillated by the dye laser oscillator, a fundamental wave having a small divergence angle and a high beam quality can be easily obtained, and the wavelength conversion efficiency by the nonlinear optical crystal increases. That is, it is possible to obtain exposure light more efficiently than directly converting the wavelength of the yellow component laser light obtained from the copper laser oscillator.

Sixth, by injecting the yellow component laser light generated from the copper laser oscillator into the dye laser, not only is the wavelength selecting element unnecessary, but also the wavelength of the fundamental wave can be easily stabilized. Therefore, the wavelength of the exposure light after the wavelength conversion can be stabilized, and the exposure pattern does not blur.
Further, the wavelength width can be made several pm without using a band-narrowing element in a dye laser oscillator, and it can be used as it is in an exposure lens using an achromatic lens.

Seventh, since the number of repetitions of the exposure light is about ten times as high as that of the conventional excimer laser, the exposure light itself can be irradiated while scanning the wafer, and the uniformity can be obtained. Exposure can be given. Furthermore, speckle noise can be canceled.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say, there is.

For example, the exposure light source of the present invention is not only used as an exposure light source for an exposure apparatus used for photolithography in a semiconductor device manufacturing process, but also requires a laser beam having a stable wavelength in a vacuum ultraviolet region. Can be widely applied to the field.

[0075]

Advantageous effects obtained by typical ones of the inventions disclosed in the present application will be briefly described.
It is as follows.

According to the exposure light source of the present invention, an effect is obtained that, instead of an ArF excimer laser, exposure light in a vacuum ultraviolet region having a sufficiently narrow band can be generated.

According to the exposure light source of the present invention, ArF
The effect is obtained that the vacuum ultraviolet light having the same wavelength of about 193 nm as the excimer laser can be efficiently generated.

According to the exposure method of the present invention, the effect is obtained that the life of the exposure optical system can be extended and the exposure apparatus can be used for a long time.

According to the exposure method of the present invention, it is possible to reduce the cost and improve the throughput in the exposure step.

According to the exposure apparatus of the present invention, there is obtained an effect that the life of the exposure optical system can be extended and the exposure apparatus can be used for a long time.

According to the exposure apparatus of the present invention, it is possible to reduce the cost and improve the throughput in the exposure step.

According to the method of manufacturing a semiconductor device of the present invention,
An effect is obtained that a semiconductor device having a design rule of a wavelength in a vacuum ultraviolet region can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of an exposure light source according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an example of a configuration of a dye laser oscillator according to a first embodiment of the exposure light source of the present invention.

FIG. 3 is a conceptual diagram showing an example of a configuration of a first embodiment of the exposure apparatus of the present invention.

FIG. 4 is a conceptual diagram showing an example of the configuration of a second embodiment of the exposure light source of the present invention.

FIG. 5 is a conceptual diagram illustrating an example of a configuration of a second embodiment of the exposure apparatus of the present invention.

FIG. 6 is a conceptual diagram showing an example of the operation of the exposure apparatus according to the second embodiment of the present invention.

FIG. 7 is a conceptual diagram showing an example of the operation of the exposure apparatus according to the second embodiment of the present invention.

8A to 8C are cross-sectional views illustrating an example of a method for manufacturing a semiconductor device using an exposure light source and an exposure apparatus according to the present invention in the order of steps.

[Explanation of symbols]

 1 Copper Laser Oscillator 1a Discharge Tube 2 Copper Laser Amplifier 2b Discharge Tube 3a Beam Diameter Converter 3b Beam Diameter Converter 3c Beam Diameter Converter 4a Dichroic Mirror 4b Dichroic Mirror 5a Mirror 5b Mirror 5c Mirror 5d Mirror 6 Dye Laser Oscillator 7 Dye Laser Amplifier 8a Beam splitter 8b Beam splitter 9a Dye jet 9b Dye jet 10 Lens 10b Lens 11a Nonlinear optical crystal 11b Nonlinear optical crystal 12 Pinhole plate 13 Etalon 21 Copper laser oscillator 22 Discharge tube for copper laser 23 Beam diameter converter 24 Dye laser oscillator Reference Signs List 25 dye jet 26 etalon 27 diffraction grating 31a output mirror 31b output mirror 32a output mirror 32b output mirror 33a total reflection mirror 33b total reflection mirror 34 total reflection mirror 100 exposure light source 1 0 Exposure light source 150 Stepper body 200 Exposure device 201a Mirror 201b Mirror 201c Mirror 202 Beam diameter converter 203 Random phase plate 204 Fly-eye lens 205 Condenser lens 206 Reticle 207 Reduction projection lens 208 Wafer stage 209 Wafer 300 Stepper body 301 Polygon mirror 302 fθ Lens 303 Reticle 304 Irradiation section 305 Mask 306 Movable section 307 Reticle stage 308 Reduction projection lens 309 Wafer 310 Movable section 311 Wafer stage 1001 Silicon substrate 1002 Insulating film 1002a Contact hole 1003 Resist 1003a Hole

Claims (9)

[Claims] 1. A laser comprising: a copper laser; a dye laser; and at least two nonlinear optical crystals; operating the dye laser using laser light extracted from the copper laser as excitation light; An exposure light source, wherein the laser light passes through the nonlinear optical crystal and is output as exposure light. 2. The exposure light source according to claim 1, wherein the copper laser includes a copper laser oscillation unit and a copper laser amplification unit that amplifies a laser beam output from the copper laser oscillation unit, and is extracted from the dye laser. An exposure light source, wherein the laser light passes through the copper laser amplifying unit and then passes through the nonlinear optical crystal and is output as the exposure light. 3. The exposure light source according to claim 2, wherein the wavelength of about 578 of the laser light having a wavelength of about 578 nm and a wavelength of about 511 nm output from the copper laser oscillation unit.
nm laser light is incident on the dye laser and has a wavelength of about 5 nm.
The 11 nm laser light is incident on the dye laser via the copper laser amplifying unit, and causes the laser light having a wavelength of about 578 nm output from the dye laser to pass through the copper laser amplifying unit and the nonlinear optical crystal. An exposure light source for outputting the exposure light. 4. An exposure method, characterized in that laser light output from a dye laser excited by a copper laser and wavelength-converted by at least two nonlinear optical crystals is used as exposure light. 5. An exposure apparatus, comprising: an exposure light source for generating exposure light; and an exposure optical system for irradiating the exposure light to an object to be exposed via a reticle. An exposure apparatus comprising the exposure light source according to 2 or 3. 6. The exposure apparatus according to claim 5, wherein the reticle and the exposure object are displaced synchronously in a direction intersecting an optical axis of the exposure light, so that the reticle and the exposure light are exposed to the exposure light. An exposure apparatus for performing a scanning exposure for relatively scanning an object. 7. An exposure apparatus according to claim 6, wherein the exposure light is obtained from the exposure light source according to claim 1, in a direction intersecting a main scanning direction due to displacement of the reticle and the exposure object. An exposure apparatus characterized in that sub-scanning is performed by using. 8. An exposure apparatus according to claim 7, wherein the exposure light obtained from the exposure light source according to claim 1, 2, or 3 is irradiated via a polygon mirror so as to scan the reticle. The exposure apparatus according to claim 1, wherein the sub-scanning is performed. 9. A method of manufacturing a semiconductor device by photolithography in which a reticle pattern is transferred to a semiconductor wafer via exposure light, wherein the photolithography includes the exposure method according to claim 4, or A method for manufacturing a semiconductor device, comprising using the exposure apparatus according to claim 5.