JPH1022217A - Aligner for manufacturing integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To comprise the aligner at a low cost for the entire optical system so as to be easily manufacture without deteriorating the durability and quality, even in the case of using the optical system comprising hydrogen-doped quartz glass to configure an ArF excimer laser exposure device. SOLUTION: At least a lens being a component of an optical system 5 comprises an optical member made of a hydrogen-doped synthetic quartz glass with different hydrogen molecular concentration, and especially optical members placed toward a wafer are made of a synthetic quartz glass member containing hydrogen molecules whose hydrogen molecular concentration is within a range of 5×10<18> -5×10<19> molecules/cm<3> , whose homogeneity Δn of refracting power is 5×10<-6> /1cm or below and whose double refracting power is 5nm/cm or below. On the other hand, optical members placed toward a light source are made of a synthetic quartz glass member containing hydrogen molecules whose hydrogen molecular concentration is within a range of 1×10<17> -5×10<18> molecules/cm<3> , whose homogeneity Δn of refracting power is 3×10<-6> /1cm or below and whose double refracting power is 3nm/cm or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for manufacturing an integrated circuit in the range of 64M to 256M, and more particularly to an optical system made of quartz glass which illuminates a pattern of an integrated circuit with laser light from an ArF excimer laser. To print an integrated circuit pattern on a wafer to manufacture an integrated circuit.

[0002]

2. Description of the Related Art Conventionally, an optical lithography technique for transferring a pattern on a mask onto a wafer using light is superior in cost in comparison with other techniques using an electron beam or a Χ-ray, so that an integrated circuit is used. Is widely used as an exposure apparatus for manufacturing a semiconductor device. Conventionally, an exposure apparatus utilizing such photolithography technology has a light source of a wavelength of 36 emitted from a high-pressure mercury lamp.
An exposure apparatus has been developed to form a pattern having a line width of 0.5 to 0.4 μm using an i-line of 5 nm.
It corresponds to an integrated circuit below the bit-DRAM. On the other hand, for next generation 64Mbit ~ 256Mbit, 0.25 ~
An imaging performance of 0.35 μm, and 0.13-0.
Although a resolution of 20 μm is required, a resolution of 0.35 μm is lower than the wavelength of the i-line, and KrF light is used as a light source. And in the region below 0.20 μm, Kr
ArF light, particularly an ArF excimer laser, is used instead of F light.

However, there are various problems in the optical lithography technique using an ArF excimer laser, one of which is a problem of an optical material for forming a lens, a mirror and a prism constituting a projection optical system. That is, 19 of ArF
Optical materials having a good transmittance at a wavelength of 3 nm are substantially limited to quartz glass, particularly high-purity synthetic quartz glass.
F light damages quartz glass more than KrF light
10 times larger.

Now, the resistance of quartz glass to irradiation with excimer laser is described in Japanese Patent Application No. 1-11 filed by the present applicant.
45226 depending on the concentration of hydrogen contained. For this reason, in a conventional exposure apparatus using a KrF excimer laser as a light source, if the concentration of hydrogen contained in the quartz glass constituting the optical system is 5 × 10 ¹⁶ molecules / cm ³ or more, sufficient durability can be secured. It is described in the art. However, since the influence of ArF laser light on quartz glass is greater than that of KrF as described above, the degree of damage (change in transmittance and change in refractive index) caused to synthetic quartz glass by ArF laser light is limited. Examination shows that the required hydrogen molecule concentration is Kr
In some cases, it was found that the concentration of hydrogen molecules was required to be 100 to 1000 times or more higher than that of the F laser light, specifically, a hydrogen molecule concentration of 5 × 10 ¹⁸ molecules / cm ³ or more was required.

[0005] The concentration of hydrogen molecules contained in the quartz glass constituting the optical system is a number determined by the conditions for synthesizing the raw material and / or the conditions of the subsequent heat treatment step (including hydrogen dope). The hydrogen molecule concentration is uniquely determined if the range due to process variation is ignored.
Therefore, a synthetic quartz glass member used for an optical system such as a mirror and a lens constituting an exposure apparatus is composed of only one kind of synthetic quartz glass from the viewpoint of hydrogen concentration. There are two methods of including hydrogen molecules in synthetic quartz glass. First, when adjusting the atmosphere during manufacture and including hydrogen molecules in synthetic quartz glass at normal pressure, the concentration of hydrogen molecules that can be included is up to 5 × It is up to about 10 ¹⁸ molecules / cm ³ . As another method, even when hydrogen molecules are doped into quartz glass by pressurized heat treatment in a hydrogen atmosphere, hydrogen molecules introduced in hydrogen treatment at an upper limit of 10 atm / cm ² which are not subject to the high-pressure gas control method. The concentration is still 5 × 1
0 ¹⁸ molecules / cm ³ is the upper limit.

For this reason, 5 × 10 ¹⁸ molecules / c are contained in quartz glass.
In the case of including hydrogen molecules of m ³ or more, it is necessary to perform heat treatment at a high hydrogen pressure which is much higher than 10 atm. For example, Japanese Patent Application Laid-Open No. 4-164 filed by the present applicant
In 833, a temperature of 1750 ° C. is re-melted and heat-treated in a high-pressure atmosphere of argon gas 100% to reduce the temperature to approximately 5 ° C.
A technique capable of doping hydrogen molecules of about × 10 ¹⁸ (molecules / cm ³ ) is disclosed.

[0007]

However, the re-melting heat treatment at a temperature of 1750 ° C. is preferably performed at a heat treatment temperature in the range of 200 to 800 ° C. in order to induce new defects in quartz glass. Japanese Patent Application Laid-Open No. Hei 6-166528).
When introducing a large amount of hydrogen molecules of ¹⁸ molecules / cm ³ or more,
Since the diffusion rate of hydrogen molecules is not very high, the processing of large optical members takes a very long time.In addition, heat treatment in a high-pressure atmosphere reduces the homogeneity of the refractive index of the quartz glass optical members. Also, there is a problem that distortion is introduced. Therefore, even when the high-pressure heat treatment is performed, heat treatment for re-adjustment is necessary, and therefore, contains a hydrogen molecule of 5 × 10 ¹⁸ molecules / cm ³ or more and has a refractive index sufficient to constitute an optical system of the exposure apparatus. Quartz glass having optical properties such as homogeneity and low distortion is industrially extremely complicated and extremely expensive after a long time treatment.

According to the present invention, even when an ArF excimer laser exposure apparatus is constructed using an optical system made of hydrogen-doped quartz glass, the optical system as a whole can be manufactured without deteriorating the quality such as durability and light transmittance. It is an object of the present invention to provide an exposure apparatus which can be easily manufactured at low cost.

[0009]

The present invention focuses on the following points. First, as described above, in order to improve the durability of an ArF excimer laser exposure apparatus, containing hydrogen molecules of 5 × 10 ¹⁸ molecules / cm ³ or more is industrially extremely complicated and requires a long time treatment. It is difficult to manufacture and very expensive. On the other hand, Reference 2 (New Gl
According to ass VoL6 No, 2 (1989) 191-196 "Quartz glass for steppers", written by Kazuo Ushida), 99.0 (lowest level) as transmittance required as an exposure device required for stepper projection lenses, etc.
% / Cm or more, the refractive index distribution (Δn) is ≦ 1 × 10 ⁻⁶ , and the birefringence is nm / cm ≦ 1.00. However, as described above, 5 × 10 ¹⁸ molecules / cm ³ are obtained by the pressure treatment. When high-concentration hydrogen doping is performed, quartz glass having a uniform refractive index cannot be obtained as described above. On the other hand, if quartz glass is manufactured with emphasis on the refractive index, it is not possible to obtain a high-concentration hydrogen-doped glass, and damage may occur when irradiated with ArF excimer laser.

Accordingly, the present invention manufactures an integrated circuit by illuminating a pattern of the integrated circuit with laser light from an ArF excimer laser, and projecting and printing the pattern of the integrated circuit on a wafer by an optical system made of a quartz glass material. In the exposure apparatus, the synthetic quartz glass optical member constituting the optical system is composed of a plurality of types of hydrogen-doped synthetic quartz glass optical members having different hydrogen molecule concentrations, and the optical member Achieving high transmittance as a whole optical system by effectively combining a plurality of optical members having different hydrogen molecule concentrations and homogeneities in accordance with the light energy density ε (mJ / cm ² ) transmitted through the members. It is characterized by the following.

That is, more specifically, at least the light energy density ε (mJ / cm ² ) which is disposed closest to the wafer exposure surface and / or the pupil surface and which transmits the optical member is the largest. The hydrogen molecule concentration of the first optical member (hereinafter, referred to as a wafer-side optical member) is adjusted to the wafer exposure surface or /
And hydrogen molecules of at least one optical member (hereinafter referred to as a light source side optical member) disposed at a position furthest away from the pupil plane and at a position where the light energy density ε (mJ / cm ² ) transmitted through the optical member is the smallest. Greater than concentration, while refractive index distribution
Regarding the homogeneity of (Δn) and the birefringence amount nm / cm, the light source side optical member is set to be better than the uniformity of the wafer side optical member, and high transmittance as the whole optical system is achieved. Things.

Preferably, the wafer-side optical member is made of a quartz glass optical material having a hydrogen molecule concentration of 5 × 10 ¹⁸ molecules / cm ³ or more and 5 × 10 ¹⁹ molecules / cm ³ or less, and the light source-side optical member is provided. Is 1 × 10 ¹⁷ molecules / cm ³ or more 5 × 10 ¹⁸
It is composed of silica glass optical material having a less molecules / cm ³ of hydrogen molecule concentration, and more preferably the wafer side optical element is, 5 × 10 ¹⁸ molecules / cm ³ to 5 × 10 ¹⁹ molecules /
cm ³ hydrogen molecules, and the refractive power homogeneity Δn is 5 × 10
^-6/1 cm or less and a birefringence of 5 nm / cm or less, and made of a synthetic quartz glass material.
Synthesis containing hydrogen molecules of × 10 ¹⁷ molecules / cm ³ to 5 × 10 ¹⁸ molecules / cm ³ , homogeneity of refractive index Δn of 3 × 10 ⁻⁶ / 1 cm or less, and birefringence of 3 nm / cm or less It is characterized by being formed of a quartz glass material.

According to a fourth aspect of the present invention, a projection optical system having a pupil plane focuses on the fact that the diameter of the pupil plane is 30 to 50 mm in an exposure apparatus for manufacturing an integrated circuit. That is, the lens group constituting the projection optical system is constituted by a plurality of kinds of quartz glass optical members having different hydrogen doping concentrations, and the diameter of the lens group is φ80 m.
m (corresponding to the lens group on the wafer side) has a hydrogen molecule concentration of 5 × 10 ¹⁸ molecules / cm ³ or more and 5 × 10 ¹⁹ molecules / cm ³ or less, and the refractive index homogeneity Δn is 5 × 10 ^-6
A lens group having a diameter of φ80 or more and φ100 mm or less is composed of 5 × 10 ¹⁷ molecules / cm ³ or more and 5 × 10 ¹⁸ molecules / cm ³ or less of a quartz glass material having a birefringence of 5 nm / cm or less. A lens group having a density, a refractive index homogeneity Δn of 3 × 10 ⁻⁶ or less and a birefringence of 3 nm / cm or less, and a lens group having a diameter of φ100 mm or more (the light source side lens group); 1 × 10 ¹⁷ molecules /
A quartz glass optical member having a hydrogen molecule concentration of not less than 5 cm ^{3 and not} more than 5 × 10 ¹⁸ molecules / cm ³ , having a refractive index homogeneity Δn of not more than 1 × 10 ⁻⁶ and a birefringence of not more than 1 nm / cm. It is characterized by being composed.

According to a fifth aspect of the present invention, the object of the present invention is achieved more smoothly by combining an optical path length and the like with the fourth aspect of the present invention, and a quartz glass optical member constituting an optical system of an exposure apparatus. Among them, the sum of the optical path lengths of optical members such as lenses having a diameter of φ80 mm or less is 20% or less of the entire optical system, preferably
15% or less, and the total optical path length of optical members such as lenses with a diameter of φ80mm or more and φ100mm or less is 20% of the entire optical path length of the optical system.
Or less, preferably 15% or less.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. It's just FIG.
FIG. 1 is a schematic configuration diagram of a lithography exposure apparatus using an ArF excimer laser applied to the present invention. 1 is an ArF excimer laser light source, and 2 is a deformation for forming a pattern image on a wafer surface without interference of diffraction light. The illuminating means has, for example, a quadrupole illumination or an annular illumination light source shape in which a central portion is a light shielding surface. 3 is a condenser lens for guiding the excimer laser light emitted from the light source to the reticle, 4 is a mask (reticle), 5 is a projection optical system,
For example, by combining a lens group having a positive refractive power and a lens group having a negative refractive power to narrow the band of light, a pupil plane is formed in the optical system to improve the resolution. Reference numeral 6 denotes a wafer mounted on a wafer stage 7 and the reticle 4
Is formed on the wafer 6 via the projection optical system.

In this apparatus, the projection optical system includes a condenser lens group 5a disposed closest to the wafer surface and a lens group 5b disposed near the pupil plane in order to form pattern light on the wafer surface. Exists, but a secondary light source which is an image of the light source is formed on the pupil plane. Therefore, when a light source image discretely appears on the pupil plane, energy concentrates on the light source image, which causes damage to the optical system together with the wafer side. On the other hand, on the reticle side, the energy density becomes smaller by the square of the imaging magnification as compared with the wafer side.

This embodiment focuses on such a point, that is, specifically, the size of the pupil plane of the ArF excimer laser is about φ30 to φ50 mm according to the reference document. It is reasonable to determine the energy density on the basis of double. For example, if the reticle sensitivity is 20 to 50 mJ and this is exposed by laser irradiation of 20 to 30 pulses, the energy density per pulse on the pupil plane is 0.7 to 1.7 mJ / cm ² , and more precisely, the energy on the exposure plane and the pupil plane is energy. The densities are different, and even if it is assumed that the wafer surface is slightly larger, the energy density of the wafer-side lens group arranged closest to the wafer surface is about 0.6 to 1.5 mJ, which is about 80 to 90% of that. / Cm ² . It is also assumed that the pupil plane is slightly lower. On the other hand, in order to improve the resolution, the projection optical system is configured by combining a lens group having a positive refractive power and a lens group having a negative refractive power (for example, Japanese Patent Application Laid-Open No. 3-343).
In this case, it is necessary to eliminate aberrations in each lens group as much as possible. In such a case, it is better to set the actual reduction or enlargement magnification of each lens group to some extent. The energy density of the next lens unit from the wafer side or the closest position to the pupil plane is 0.6 to 1.5.
about 1/3 of mJ / cm ² , specifically 0.2 to 0.6 mJ /
It is estimated to be of the order of cm ² . Most of the other lens groups (including the light source side lens) have an energy density per pulse ε ≦ 0.2 mJ / cm ² . Therefore, in the lens group in which the energy density per pulse is ε ≦ 0.2 mJ / cm ² in the wafer-side lens group, the emphasis is placed on optical homogeneity rather than durability, so that the resolution of the entire optical system is improved. I can do it. Therefore, in the present embodiment, in the case of the light source side optical member of ε: ≦ 0.2 mJ / cm ² , the hydrogen molecule concentration C _{H2 is set} to 1 × 10 ¹⁷ ≦ C _H2 ≦ 5 × 10 ¹⁸ molecules /
cm ³ , the refractive index distribution (Δn) is ≦ 1 × 10
^-6 , the birefringence is maintained at a high quality of ≦ 1.00 nm / cm.

The wafer closest to the pupil plane and the wafer
-Energy per pulse in the c-side lens group
In the lens group whose density is 0.6 ≦ ε ≦ 1.5, the durability is
Focus on the durability of the optical system as a whole.
I can go up. Therefore, in the present embodiment, ε: 0.6 ≦ ε
≤1.5 mJ / cm^Two, The hydrogen molecule concentration C H
_TwoTo 5 × 10¹⁸≤C_H2≦ 5 × 10¹⁹Molecule / cm^ThreeSet high
Also, the refractive index distribution (Δn) is ≦ 5 × 10^-6, Birefringence ≤5.0n
m / cm is set gently to facilitate production. Further
The received light energy is located at the next stage such as a high-density lens
An optical member such as a lens takes an intermediate point between the two, and ε: 0.2
≦ ε ≦ 0.6 mJ / cm^TwoIn the case of the optical system of
Degree C_H2To 5 × 10¹⁷≤C_H2≦ 5 × 10¹⁸Molecule / cm^ThreeAgain
Fold distribution (Δn) ≦ 3 × 10^-6, Birefringence is ≤3.0 nm / c
m is set gently to facilitate manufacturing. And 0.6
≦ ε ≦ 1.5 mJ / cm^TwoThe total optical path length of the optical members
20% or less, preferably 15% or less of the optical path length of the entire optical system
And the ε: 0.6 ≦ ε ≦ 1.5 mJ / cm^TwoLight of optical members
Total path length is 20% or less of the total optical path length of the optical system, preferably
Is to combine and arrange optical systems so that it is less than 15%
As shown in the examples below, while maintaining durability, optical
High transmittance can be achieved as a whole system.

Now, when considering the lens material constituting the projection optical system, it is necessary to decide what the diameter of the lens or the like should be and the degree of deterioration is severe. However, according to the above-mentioned reference, the ArF excimer laser is used. Of the pupil plane is about φ30 to φ50 mm, and it is reasonable to determine the pupil plane on the basis of several times this area. That is, 0.6 ≦ ε ≦ 1.5 mJ at a position close to the pupil plane or the wafer plane.
Considering that the maximum value of the pupil plane is φ50 mm when the use area is 80%, the lens diameter for receiving an ArF excimer laser having an energy density of / cm ² is about φ80 mm at maximum, and therefore ε: 0.6 ≦ ε ≦ 1.5m
It is estimated that the lens diameter of the optical member of J / cm ² is about 80φ or less. Further, by the same calculation, ε: 0.2 ≦ ε ≦ 0.6
In the case of a lens of mJ / cm ² or the like, the magnification is about 2 to 3 times the pupil plane.
Corresponds to lenses around 100mm. And no more (1
Energy density ε: ≧ 0.2 m with a lens diameter of 00 mm)
J / cm ² . And also in this case, diameter φ80m
The total of the optical path lengths of the optical members such as lenses having a diameter of m or less is 20% or less, preferably 15% or less of the entire optical system, and the total of the optical path lengths of the optical members such as the lenses having a diameter of 80 mm or more and 100 mm or less is the optical path length of the optical system. It is good to set it to 20% or less, preferably 15% or less of the whole.

The present invention can be applied not only to the projection optical system exposure apparatus shown in FIG. 1 but also to a reflection optical system exposure apparatus. That is, FIG. 2 is a schematic diagram showing a configuration of a lens and the like of a reflection optical system exposure apparatus using a prism type beam splitter in order to achieve high resolution. Light passing through the beam splitter 13 through the second lens group 14 passes through the second lens group 14,
After that, the light is turned by the mirror 15 and then the third lens group 1
6, the reticle 17 is scanned with the condensed light, and then returns to the beam splitter 13 again via the third lens group 16, the mirror 15, and the second lens group 14, and this time the splitter 13 Then, the image is formed by the fourth lens group 19 and the integrated circuit pattern is printed on the wafer 18. According to such an apparatus, the fourth lens group 19 closest to the wafer after being turned to the splitter 13 receives the strongest light energy with an energy density per pulse of 0.6 ≦ ε ≦ 1.5 mJ / cm ² , so that the hydrogen molecule concentration C _H2 Molecule / cm
^{Although 3} is set as high as 5 × 10 ¹⁸ ≦ C _H2 ≦ 5 × 10 ¹⁹ , the refractive index distribution (Δn) may be set to ≦ 5 × 10 ⁻⁶ and the birefringence may be set to ≦ 5.0 nm / cm gently. In the present apparatus, since the third lens group 16 is focused / scanned on the reticle 17 side, the energy density per pulse is 0.2 ≦ ε ≦
Since it is presumed to receive an energy of 0.6 mJ / cm ^2, the hydrogen molecule concentration C _H2 molecule / cm ^{3 is set} to 5 × 10 ¹⁷ ≦ C _H2 ≦ 5 × 10 ¹⁸
, The refractive index distribution (Δn) is ≦ 3 × 10 ⁻⁶ , and the birefringence is ≦
It may be set as gently as 3.0 nm / cm, and other lenses, mirrors, and prism type beam splitters,
In particular, since the optical member near the light source side receives only the energy of energy density ε ≦ 0.2 mJ / cm ² per pulse, the hydrogen molecule concentration C _H2 molecule /
Although cm ³ is set to 1 × 10 ¹⁷ ≦ C _H2 ≦ 5 × 10 ¹⁸ , the refractive index distribution (Δn) is maintained at ≦ 1 × 10 ⁻⁶ and the birefringence is maintained at a high quality of ≦ 1 nm / cm.

The relationship between the lens diameters is the same as that described above, and the fourth lens group 1 in which the lens diameter is set to φ80 mm or less.
9 is less than 20% of the optical path length of the entire optical system,
Preferably, the lens aperture is φ80 to 100 m at 15% or less.
In this embodiment, the optical systems are combined and arranged so that the total optical path length of the optical members of the third lens group 16 set to m is 20% or less, preferably 15% or less of the entire optical path length of the optical system. However, it is estimated that the optical system as a whole can achieve a transmittance of 99.8% / cm while maintaining durability.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exposure apparatus shown in FIGS. 1 and 2, it takes a very long time to confirm the long-term stability of optical characteristics under actual operating conditions. Only a quartz glass optical member to be manufactured was taken out, and a simulation experiment in which actual operation was accelerated was performed.

In general, the progression rate of damage in laser irradiation of quartz glass increases in proportion to the square of the energy density (fluence) of the irradiated excimer laser (Optics Vol. 23, No. 10, "Quartz Glass for Excimer Laser", Akira Fujinoki). This is used as a reference for acceleration experiments.

A quartz glass ingot was prepared by a so-called DQ method in which silicon tetrachloride was deposited on a rotating substrate while being hydrolyzed by an oxyhydrogen flame. The obtained quartz glass ingot contained 800 to 1000 ppm of OH groups and contained 5 × 10 ¹⁸ molecules / cm ^{2 of} hydrogen molecules. This quartz glass ingot was homogenized by the method described in JP-A-7-267662, and was heated and gradually cooled at 1150 ° C. for 40 hours for strain relief annealing. The optical properties of the obtained homogeneous quartz glass material for optics were measured, but there were no striae in three directions.
When the refractive index distribution was measured with an interferometer (Zygo Mark IV), Δn showed an extremely good value of 1 × 10 ⁻⁶ . The amount of birefringence was measured using a crossed Nicols strain gauge, and the amount of birefringence was 1 nm / cm or less.

This quartz glass material for optics is disclosed in Reference 2 (New
Glass VoL6 No, 2 (1989) 191-196 "Quartz glass for steppers" by Kazuo Ushida), which satisfies the optical characteristics required for quartz glass members used in excimer laser steppers. By configuring an optical component using a glass material, a semiconductor exposure apparatus using ArF as a light source can be manufactured. On the other hand, when the concentration of hydrogen molecules contained in the quartz glass material for optics was measured by a laser Raman method, it was 5 × 10 ¹⁷ molecules / cm ² . (Sample number A)

The optical quartz glass material is φ60 mm
Xt20mm sample is cut out at 1000 ℃
After performing the oxidation treatment for a period of time, hydrogen doping treatment was performed in an autoclave in a high-pressure (50 atm) atmosphere of hydrogen gas at 600 ° C. for 1000 hours. When the refractive index distribution of the sample after the treatment was measured, Δn was 4 × 10 ⁻⁶ and the amount of birefringence was 5 nm / c.
m, the concentration of hydrogen molecules contained was 2 × 10 ¹⁹ molecules / cm ² . (Sample No. D) The content of hydrogen molecules was measured using a Raman spectrophotometer, which is a Raman spectrophotometer NR manufactured by JASCO Corporation.
Using a 1100, an Ar laser beam with an excitation wavelength of 488 nm and an output of 700 mW, Homamatsu Photonics R943
Performed by the host counting method using -02.
The hydrogen molecule content is obtained by converting the area intensity ratio between the SiO ₂ scattering band observed at 800 cm ⁻¹ and the hydrogen scattering band observed at 4135-40 cm ⁻¹ in the Raman scattering spectrum at this time into a concentration. I asked. Conversion constants are based on literature values
4135cm ^-1 / 800cm ^-1 × 1.22 × 10 ²¹ (Zhurnal Pri-Kl
adnoi Spektroskopii, Vol. 46, No. 6, PP987-991, June, 1
987) was used.

Further, from the quartz glass material for optics, φ60 mm
Xt20mm sample is cut out at 1000 ℃
After performing the oxidation treatment for a period of time, hydrogen doping treatment was performed in an atmosphere furnace under a pressurized hydrogen gas atmosphere (9 atm) at 600 ° C. for 1000 hours. When the refractive index distribution of the sample after the treatment was measured, Δn was 3 × 10 ⁻⁶ , the amount of birefringence was 3 nm / cm, and the concentration of contained hydrogen molecules was 5 × 10 ¹⁸ molecules / cm ² . (Sample number B)

Again from the quartz glass material for optics, φ60 mm
Xt20mm sample is cut out at 1000 ℃
After performing the oxidation treatment for a period of time, hydrogen doping treatment was performed at 600 ° C. for 1000 hours in a hydrogen gas pressurized (3 atm) atmosphere in an atmosphere furnace. When the refractive index distribution of the sample after the treatment was measured, Δn was 2 × 10 ⁻⁶ , the amount of birefringence was 2 nm / cm, and the concentration of contained hydrogen molecules was 2 × 10 ¹⁸ molecules / cm ² . (Sample number C)

Here, except for the samples A and C, only one kind of quartz glass is not sufficient in homogeneity to constitute an exposure apparatus using an ArF excimer laser as a light source. Although the amount was found to be too large, the optical members represented by the samples A, B, C, and D were converted into the optical path length as the projection optical system of the apparatus of FIG.
When the homogeneity of the refractive index of the entire optical system was calculated assuming that the lens system was configured at 1: 1, Δn per 1 cm of the optical path was 2 × 10 ⁻⁶ and the average value of birefringence was 2 nm / cm. It was found that sufficient optical characteristics were obtained to constitute the above.

The transmittance of the four samples to ultraviolet light having a wavelength of 193 nm was measured with an ultraviolet spectrophotometer.
A good value was shown for the internal transmittance per cm. Again, it has sufficient transmittance to constitute an excimer laser stepper.

The four samples thus obtained were irradiated with an ArF excimer laser to examine changes in optical characteristics. The irradiation condition is that the energy density per pulse is 10 mJ / cm
^{2. The} irradiation frequency was 300 Hz. This is, as shown in Document 1, when the light energy density of a laser transmitted through an optical member in an actual operation is εmJ / cm ² , (100
/ Epsilon) corresponds to an accelerated test ^twice. Table 1 shows the results of excimer laser irradiation of each sample. The number of irradiation was 2.5 × 10 ⁷ shots, showing a change in the transmittance at 193 nm and a change in the refractive index due to this irradiation.

[0032]

[Table 1]

For sample D, the amount of change in the refractive index was too small to perform an accurate measurement. From these results, it was found that the change in the refractive index of the optical member due to the irradiation of the ArF laser was the most important parameter as a parameter for determining the stability of the exposure apparatus. Since sufficient measurement accuracy was not obtained for sample D,
The relationship between the hydrogen concentration and the rate of increase in the refractive index was determined using the results of Samples A to C, and the extrapolation was performed to calculate.

Here, from the conditions of the acceleration simulation experiment, the acceleration rate with respect to the case where the energy density of the ArF excimer laser beam transmitted through the quartz glass optical member is εmJ / cm ^{2 in} the actual operation of the exposure apparatus is (100)
/ Epsilon) it is considered to be ^twice the energy density of the ArF excimer laser light is expected refractive index of 1 × 10 ¹⁰ shots after in the case of 0.6 mJ / cm ² (3 years at 100Hz of continuous irradiation) The change is as shown in the table below for each sample.

[Table 2] Sample number Estimated value of change in refractive index after irradiation Judgment A 4.04 × 10 ^-7 usable B 1.60 × 10 ^-7 usable C 8.68 × 10 ^-8 usable D 3.42 × 10 ^-8 usable

Since sufficient measurement accuracy was not obtained for Sample D, the relationship between the hydrogen concentration and the rate of increase in the refractive index was obtained using the results of Samples A to C, and this was extrapolated and calculated.

Next, when the energy density of the ArF excimer laser beam is 0.6 mJ / cm ² , the expected change in the refractive index after 1 × 10 ¹⁰ shots (3 years with continuous irradiation at 100 Hz) is shown in the following table for each sample. become that way.

[0037]

[Table 3] Sample No. Expected value of change in refractive index after irradiation Judgment A 3.63 × 10 ^-6 cannot be used B 1.14 × 10 ^-6 can be used C 7.81 × 10 ^-7 can be used D 3.08 × 10 ^-7 can be used

Next, when the energy density of the ArF excimer laser beam is 1.0 mJ / cm ² , the expected change in the refractive index after 1 × 10 ¹⁰ shots (3 years with continuous irradiation at 100 Hz) is shown in the following table for each sample. become that way.

[0039]

[Table 4] Sample No. Expected value of refractive index change after irradiation Judgment A 1.01 × 10 ^-5 Not available B 4.00 × 10 ^-6 Not available C 2.17 × 10 ^-6 Not available D 8.56 × 10 ^-7 Available

According to this simulation experiment, an exposure apparatus comprising an optical system composed of a plurality of types of synthetic quartz glass optical members as defined in the claims achieves sufficient stability of optical characteristics for a long period of time even in actual operation. It is expected to be possible.

[0041]

As described above, according to the present invention, ArF is formed by using an optical system made of hydrogen-doped quartz glass.
Even when configuring an excimer laser exposure device,
The optical system as a whole can be easily manufactured at low cost without deteriorating durability and quality.

[Brief description of the drawings]

FIG. 1 is an exposure apparatus for manufacturing an integrated circuit using a projection optical system to which the present invention is applied.

FIG. 2 is an exposure apparatus for manufacturing an integrated circuit using a reflection optical system to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ArF excimer laser light source 2 Deformation illumination means 3 Condenser lens 4 Mask (reticle) 5 Projection optical system 6 Wafer 11 Light source 12 First lens group 13 Beam splitter 14 Second lens group 15 Mirror 16 Third lens group 17 Reticle 19 Fourth Lens group 18 wafer

Claims (5)

[Claims] An integrated circuit is manufactured by illuminating an integrated circuit pattern with laser light from an ArF excimer laser and printing the integrated circuit pattern on a wafer by a projection optical system or a reflection optical system made of quartz glass. In the exposure apparatus, the synthetic quartz glass optical member constituting the optical system is constituted by a plurality of types of hydrogen-doped synthetic quartz glass optical members having different hydrogen molecule concentrations, and is closest to the wafer exposure surface and / or the pupil surface. Light energy density ε (mJ / cm
² ) the hydrogen molecule concentration of at least one optical member (hereinafter referred to as a wafer-side optical member) at the position where the largest is located at a position farthest from the wafer exposure surface and / or the pupil surface and transmitted through the optical member; Light energy density ε (mJ
/ Cm ² ) is larger than the hydrogen molecule concentration of at least one optical member at the position where the smallest is the smallest (hereinafter referred to as a light source side optical member), while the refractive index distribution (Δn) and the homogeneity of the birefringence amount nm / cm. An exposure apparatus for manufacturing an integrated circuit, wherein the light source side optical member is set to be more excellent than the uniformity of the wafer side optical member. 2. The wafer-side optical member is composed of a quartz glass optical material having a hydrogen molecule concentration of 5 × 10 ¹⁸ molecules / cm ³ or more and 5 × 10 ¹⁹ molecules / cm ³ or less, and 2. The semiconductor manufacturing exposure apparatus according to claim 1, wherein the exposure apparatus is made of a quartz glass optical material having a hydrogen molecule concentration of not less than × 10 ¹⁷ molecules / cm ^{3 and not} more than 5 × 10 ¹⁸ molecules / cm ³ . 3. The wafer-side optical member contains 5 × 10 ¹⁸ molecules / cm ^{3 to} 5 × 10 ¹⁹ molecules / cm ³ of hydrogen molecules,
It is formed of a synthetic quartz glass material having a refractive power homogeneity Δn of 5 × 10 ⁻⁶ / 1 cm or less and a birefringence of 5 nm / cm or less, while the light source side optical member is 1 × 10 ¹⁷ molecules / cm ³ to 5 × 10
^{Contains 18} molecules / cm ³ of hydrogen molecules and has uniformity of refractive index Δ
n is 3 × 10 ⁻⁶ / 1 cm or less and the amount of birefringence is 3 nm / c
3. An exposure apparatus for producing an integrated circuit according to claim 2, wherein said exposure apparatus is formed of a synthetic quartz glass material having a size of m or less. 4. An exposure apparatus for manufacturing an integrated circuit by illuminating a pattern of the integrated circuit with laser light from an ArF excimer laser and printing the pattern of the integrated circuit on a wafer by a projection optical system having a pupil plane. The lens group that constitutes the projection optical system is composed of a plurality of types of quartz glass optical members having different hydrogen doping concentrations, and among the lens groups, a lens group having a diameter of φ80 mm or less is 5 × 1.
Quartz having a hydrogen molecule concentration of at least ¹⁸ molecules / cm ^{3 and at most} 5 × 10 ¹⁹ molecules / cm ³ , a refractive index homogeneity Δn of at most 5 × 10 ⁻⁶ and a birefringence of at most 5 nm / cm. A lens group composed of glass material and having a diameter of φ80 or more and φ100 mm or less is 5 × 10 ¹⁷
Quartz glass optics having a hydrogen molecule concentration of not less than molecules / cm ^{3 and not} more than 5 × 10 ¹⁸ molecules / cm ³ , having a refractive index homogeneity Δn of not more than 3 × 10 ^-6 and a birefringence of not more than 3 nm / cm. A lens group composed of members and having a diameter of φ100 mm or more has a hydrogen molecule concentration of 1 × 10 ¹⁷ molecules / cm ³ or more and 5 × 10 ¹⁸ molecules / cm ³ or less, and has a refractive index homogeneity Δn of 1 × 10 ^−6. An exposure apparatus for manufacturing a semiconductor, comprising: a quartz glass optical member having a birefringence of 1 nm / cm or less. 5. The sum of the optical path lengths of optical members such as lenses having a diameter of φ80 mm or less among quartz glass optical members constituting an optical system of an exposure apparatus is 20% or less, preferably 15% or less of the entire optical system.
%, And the total optical path length of optical members such as lenses having a diameter of φ80 mm to φ100 mm is 20% or less, preferably 15% or less, of the entire optical path length of the optical system.