JPH0878324A - Manufacture of element and exposure system - Google Patents

Abstract

PURPOSE: To obtain a manufacture of an element suitable for the manufacture of a semiconductor element using light from an excimer laser as luminous flux for illumination and an exposure system. CONSTITUTION: In the manufacture of a circuit, in which a circuit pattern is illuminated by light from an excimer laser 1, the circuit pattern is projected onto a substrate to be exposed through a projection lens system and the circuit is manufactured, the projection lens system 3 is composed of a plurality of kinds of glass materials, a plurality of all lens elements constituting the projection lens system 3 are formed in a single lens, the wavelength width of light from the excimer laser 1 is narrowed, and the circuit pattern is illuminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device manufacturing method and an exposure apparatus, and more particularly to a circuit pattern on a master plate for manufacturing a semiconductor device, such as a mask and a reticle, via a refraction type imaging optical system (photographing lens system). The present invention relates to an element manufacturing method and an exposure apparatus suitable when an excimer laser is used as a light source for illuminating an original plate when performing projection exposure on a wafer (substrate to be exposed).

[0002]

2. Description of the Related Art IC, L
A very high resolving power is required for an imaging optical system for printing a pattern of a semiconductor element such as SI on a wafer such as silicon. Generally, the resolution of the projected image by the imaging optical system becomes better as the wavelength used becomes shorter, so that a light source that emits as short a wavelength as possible is used. For example, at present, light with a wavelength of 436 nm or 365 nm generated by a mercury lamp is widely used in a projection exposure apparatus.

Recently, an excimed laser (excited dimer laser) has been attracting attention as a light source of short wavelength. This excimer laser uses ArF,
KrCl, KrF, XeBr, XeCl, XeF, etc. are used, and depending on the type of these media, light with a short wavelength of 150 nm to 400 nm or a very narrow wavelength width is pulse-oscillated at a repetition frequency of 200 Hz to 300 Hz. A study applying this excimer laser to photolithography is, for example, “Photoetching of PMMA by excimer laser” (Laser Research, Vol. 8, No. 6, November 1975, published by The Institute of Laser Science, Suita, Osaka Prefecture ) Is introduced.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an element manufacturing method and an exposure apparatus suitable when an excimer laser is used as a light source for illuminating an original plate on which a pattern such as a mask and a reticle is formed. And

[0005]

The main feature of the device manufacturing method according to the present invention is to illuminate a pattern with light from an excimer laser and project the pattern onto a substrate to be exposed through a projection lens system to form the device. In the element manufacturing method to be manufactured,
The projection lens system is composed of a plurality of types of glass materials, and all of the plurality of lens elements constituting the projection lens system are single lenses to narrow the wavelength width of the light from the excimer laser to illuminate the pattern. That is.

A main feature of the exposure apparatus according to the present invention is that the exposure apparatus illuminates a mask pattern with light from an excimer laser and projects the mask pattern onto a wafer through a projection lens system. The projection lens system is composed of plural kinds of glass materials, and all of the plurality of lens elements constituting the projection lens system are composed of a single lens, and have means for narrowing the wavelength width of the light from the excimer laser. is there.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a schematic view of an embodiment of the element manufacturing method and exposure apparatus of the present invention.

In the figure, 1 is an excimer laser, M is a parallel flat glass plate made of fused silica glass, fluorite, etc., which is transparent to the light from the excimer laser 1, and is non-sensitive to the light from the excimer laser. A mask on which a circuit pattern made of a transparent metal such as chrome is formed, an original plate such as a reticle, and 2 are illumination systems for uniformly illuminating the original plate M. The lenses constituting this illumination system are light from an excimer laser. On the other hand, it is formed of a glass material having transparency and refraction.

Reference numeral 3 denotes an image forming optical system (projection lens system) for projecting the circuit pattern of the original plate M onto the surface of the wafer W. In the present embodiment, it is a reduction system having a plurality of lenses, and each lens is an excimer laser. It is formed of a glass material that is transparent to light, such as quartz or fluorite. The characteristic of the image forming optical system 3 is that in the manufacture of the integrated circuit, the distortion of the optical aberrations is almost completely corrected because the pattern printing process of the integrated circuit is performed plural times. Further, in this embodiment, since the light from the excimer laser having a single wavelength or a very narrow wavelength width is used as the illumination light, it is formed of glass having a different refractive index or dispersion for correcting axial chromatic aberration and lateral chromatic aberration. A so-called cemented lens in which two lenses are cemented together is not provided, and only a plurality of single lenses are used to achieve good aberration correction.

Reference numeral 4 denotes a supporting means for supporting the original plate M in the optical path,
A wafer chuck 5 supports the wafer W. The wafer chuck 5 is step-driven by the XY step stage 6.

In the present embodiment, the original plate M is illuminated by the luminous flux from the excimer laser 1 via the illumination system 2. The original plate M is reduced and projected onto a partial area of the wafer W by the imaging optical system 3. After the exposure, the wafer W is moved one step by the XY step stage 6, and another partial area of the wafer W is projected and exposed by the imaging optical system 3. This is repeated sequentially to expose the entire surface of the wafer W.

In this embodiment, the projection lens system is composed of a plurality of types of glass materials, all of the plurality of lens elements constituting the projection lens system are single lenses, and the wavelength width of the light from the excimer laser is narrowed. As a means, for example, an injection locking method is used, and by appropriately combining these methods, an element manufacturing method and an exposure apparatus suitable for manufacturing a semiconductor element are achieved.

Next, two kinds of embodiments of the image forming optical system 3 according to the present invention will be described in detail.

The excimer laser described below has a main oscillation wavelength of 248.5 nm, and injection locking allows light of a narrow wavelength centered at 248.5 nm to be obtained. System 3 is primarily designed to use this narrow wavelength band.

FIG. 2 is a lens sectional view of the first imaging optical system. The main feature of the image forming optical system in the same figure is three lens groups of positive, negative, and positive refracting power in order from the object side: first, second, and third lens groups I, II, and III. The first lens group I has _two lens groups, an I ₁ lens group having a negative refractive power and an I ₂ lens group having a positive refractive power, and the I ₁ lens group has a negative refractive power. has a lens L ₁₁₁ and the lens L ₁₁₂ of meniscus of negative refractive power with a convex surface facing the object side, the second I ₂ lens group of both lens surfaces is convex lenses L
₁₂₁ and at least one convex lens L _122. The second lens group II has a negative refractive power meniscus lens L ₂₁ having a convex surface facing the object side and a negative refractive power lens L _22.
And a meniscus lens L ₂₃ having a negative refractive power and having a convex surface directed toward the image side, and the third lens group III has a meniscus lens L ₃₁ having a positive refractive power and having a convex surface directed toward the image surface side. And a lens L ₃₂ having both convex lens surfaces, at least two positive refractive power lenses L ₃₃ having convex surfaces facing the object side, and at least one positive meniscus lens having a convex surface on the object side. It has a lens L ₃₄ .

The lenses L ₂₁ and L ₂₂ arranged before and after the diaphragm 50 are generally cemented lenses for correcting chromatic aberration in many image forming optical systems, but in this embodiment, these lenses are used. Is composed of a single lens.

This image forming system achieves a projection lens with good aberration correction by adopting the above-mentioned configuration. Particularly, good imaging performance is obtained within a range of a projection magnification of ⅕ and a photographing field angle of 14 × 14 mm.

Particularly, in the image forming optical system of this embodiment, it is preferable that | R _2F | <| R, where R _2F and R _2R are the radii of curvature of the object-side and image-side lens surfaces of the lens L ₂₂ , respectively. _2R | ··· (1) To satisfy the condition.

Next, each constituent element of this image forming system will be described in detail.

By constructing the I ₁ lens group with the lens L ₁₁ having a negative refractive power and the lens L ₁₁₂ having a negative meniscus shape having a negative refractive power with the convex surface facing the object side, distortion is favorably corrected over the entire screen. It is possible to print the mask pattern without distortion. Then, the negative refractive power of the I ₁ lens group is appropriately shared by the two lenses L ₁₁₁ and L ₁₁₂ to widen the angle of view and expand the printing range to improve the throughput.

Similar to the lens L ₁₁₂ , the lens L ₁₁₁ may be formed in a meniscus shape with a convex surface facing the object side, or may be configured such that both lens surfaces are concave surfaces, and good aberration correction is possible. Generated in the I _1st lens group by constructing the I ₂ lens group by a lens L ₁₂₁ whose both lens surfaces are convex and at least one meniscus lens group L ₁₂₂ having a positive refractive power and having a convex surface facing the object side. Introducing inward coma and halo aberrations are corrected to achieve high resolution. Lens L ₁₂₂
May be composed of one lens or two or more lenses. If the lens is composed of two or more lenses, the coma aberration and the halo aberration can be better corrected.

The second lens group II has a negative refractive power meniscus lens L ₂₁ having a convex surface directed toward the object side, a negative refractive power lens L ₂₂ and a negative refractive power having a convex surface directed toward the image side. By using the meniscus lens L ₂₃ , the negative spherical aberration generated in the I ₂ lens group and the sagittal flare from the middle of the screen to the periphery are corrected. In particular, the lens L ₂₂ corrects negative spherical aberration and halo aberration generated in the I ₂ lens group, and the lenses L ₂₁ and L ₂₃ correct sagittal flare in the periphery of the screen.

When the second lens group II is constructed as described above,
The light flux of the off-axis rays above the main light source is overcorrected, which causes outward coma. Therefore, the third lens group III has a positive meniscus lens L ₃₁ having a convex surface facing the image side and a lens L ₃₂ having convex lens surfaces on both sides.
By constructing at least two meniscus-shaped lenses L ₃₃ and L ₃₄ having a positive refractive power, the outward coma aberration generated in the second lens group and the field curvature and distortion aberration from the middle of the screen to the periphery are generated. In addition, it is corrected with good balance. The lenses L ₂₁ and L ₂₃ are composed of a single lens by narrowing the wavelength width of the light emitted from the excimer laser by injection locking.

The condition (1) is for strengthening the refracting power of the lens surface of the lens L _{22 on} the object side as compared with the lens surface on the image side, whereby spherical aberration near a numerical aperture of 0.3 is obtained. And the sagittal flare around the screen is corrected well.
If the condition (1) is not satisfied, it becomes difficult to satisfactorily correct spherical aberration and sagittal flare.

The lens L ₂₂ may have a concave surface on both sides or may have a meniscus shape with a convex surface facing the image side.
Any lens shape may be used as long as it satisfies the condition (1). Especially I ₁
When the lens L _{111 of the} lens group is composed of a biconcave lens, it is preferable in terms of aberration correction that the lens L ₂₂ has a meniscus shape with a convex surface facing the image plane side.

This imaging system functions sufficiently by satisfying the above-mentioned conditions, but it is preferable that the following conditions are satisfied in order to further improve the condition.

The focal lengths of the first, second and third lens groups are f ₁ , f ₂ and f ₃ , the I ₁ lens group and the I ₂ lens group, respectively.
The focal lengths of the lens groups are f ₁₁ and f ₁₂ , respectively, and the lens L _{111 is}
Where f _{111 is} the focal length of the lens and R _1F and R _1R are the radii of curvature of the object-side and image-side lens surfaces of the lens L ₁₁₁ , respectively, then 0.85 <| f ₁ / f ₂ | <2.2.・ ・ ・ ・ ・ ・ (2) 0.75 <| f ₃ / f ₂ | <1.4 ・ ・ ・ ・ ・ ・ (3) 1.4 <| f ₁₁ / f ₁₂ | <2.5 ・ ・・ ・ ・ ・ (4) 1.2 <f ₁₁₁ / f ₁₁ ｜ <2.1 ・ ・ ・ ・ ・ ・ (5) ｜ R _1F ｜ ＞ ｜ R _1R ｜ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・・ (6) To satisfy the following conditions.

The conditions (2) and (3) are for properly correcting the field curvature of the entire screen by appropriately setting the refractive power of each lens group as one of the basic lens performance.
If the lower limit is exceeded, the Petzval sum will be large and the image plane will be undercorrected. If the upper limit is exceeded, the field curvature will be overcorrected, making it difficult to satisfactorily correct aberrations on the entire screen.

Condition (4) is a condition for correcting distortion aberration by the I ₁ lens group and correction of inward coma and halo aberration by the I ₂ lens group under the refractive power arrangements of conditions (2), (3). This is for reducing the curvature of field of the entire screen to achieve high resolution. If the lower limit of the condition (4) is exceeded, the field curvature will be undercorrected, and if the upper limit is exceeded, the field curvature will be overcorrected.

The condition (5) is for appropriately setting the sharing of the negative refracting power with respect to the object-side lens L ₁₁₁ of the I ₁ lens group having the negative refracting power, and correcting the distortion satisfactorily. Condition (5)
If the lower limit of is exceeded, the distortion is undercorrected, and if the upper limit is exceeded, the distortion is overcorrected.

The condition (6) is for making the refractive power of the lens surface of the lens L _{111 on} the object side weaker than the refractive power of the lens surface on the image side, whereby the distortion aberration of the entire screen is further improved. Correcting. If the condition (6) is not satisfied, the distortion will be insufficiently corrected, which is not preferable.

In this image forming system, if the lens L ₃₃ and the lens L ₃₄ of the third lens group III are divided into three or more lenses to reduce the load of the refracting power of each lens, the coma aberration and the image plane are displayed over the entire screen. The curvature can be corrected more favorably, and higher resolution can be achieved.

As described above, according to this image forming system, a high-performance projection lens having high resolution can be achieved in the projection exposure apparatus.

Next, various numerical values of Numerical Examples 1 to 5 of the image forming system not directly related to the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap in order from the object side, and Ni is the glass of the i-th lens in order from the object side. Is the refractive index. The glass material SIO ₂ is fused silica and has a refractive index of 1.521130 at a wavelength of 248.5 nm. In the numerical example, the projection magnification is ⅕, NA = 0.3, and the screen range is 14 × 1.
This is the case of 4.

[0036]

[Outer 1]

[0037]

[Outside 2]

[0038]

[Outside 3]

[0039]

[Outside 4]

[0040]

[Outside 5] 3 to 7 show various aberrations of Numerical Examples 1 to 5 described above.
In the figure, Y is the image height, M is the meridional image plane, and S is the sagittal image plane. Next, an example of the second type reduction imaging system 3 will be described.

A sectional view of the lens of this optical system is shown in FIG. 8. The main features of this imaging optical system are, in order from the object side,
It has three lens groups A, B, and C having positive, negative, and positive refractive powers, and the first lens group A has a negative refractive power A ₁ lens group. And positive refractive power A ₂
The A ₁ lens group includes at least two image-side-side concave lenses L ₁₁₁ and L ₁₁₂ having a negative refractive power, and the A ₂ lens includes The second lens group has a lens L ₁₂₁ whose both lens surfaces are convex and a positive lens L ₁₂₂ having a positive refractive power on the object side, and the second lens group has a negative meniscus with a convex surface facing the object. A lens L ₂₁ having a concave shape, a lens L ₂₂ having concave surfaces on both sides, and a meniscus lens L ₂₃ having a negative refractive power with a convex surface facing the image side, wherein the third lens group has a convex surface on the image side. Lens L ₃₁ having a positive refractive power and a lens L ₃₂ having a convex lens surface on both sides, and at least two positive refractive power L ₃₃ having a convex surface facing the object side and a convex surface on the object side. Of at least one meniscus lens L ₃₄ having a positive refracting power.

Also in this embodiment, the lenses L ₂₁ , which are arranged in front of and behind the diaphragm 50, as in Numerical Embodiments 1 to 5, are provided.
That is, L ₂₃ is composed of a single lens.

By adopting the above-mentioned configuration, the present image forming system achieves a projection lens with good aberration correction. In particular, excellent imaging performance is obtained within a range of a projection magnification of 1/10 and a photographing field angle of 10 × 10 mm.

Next, each constituent element of the present imaging system will be described in detail.

At least two lens units A ₁₁₁ , L ₁₁₂ having a concave image side surface and having a negative refractive power, and preferably a meniscus lens L having a negative refractive power and having a convex surface facing the object side, are included in the A ₁ lens group. _{By using 111} and L ₁₁₂ , it is possible to satisfactorily correct the distortion aberration over the entire screen and print the mask pattern without distortion. The negative refracting power of the A ₁ lens group is given by the two lenses L ₁₁₁ and L _112.
The angle of view is widened and the printing range is expanded by increasing the throughput by improving the throughput.

[0046] High to correct coma and halo aberrations inward occur in A ₁ lens group by both lens surfaces of A ₂ lens unit composed of a lens L ₁₂₂ of the lens L ₁₂₁ and the positive refractive power of the convex surface The resolution is being improved.

The second lens unit B has a negative refractive power meniscus lens L ₂₁ having a convex surface facing the object side, a lens L ₂₂ having a concave surface on both lens surfaces, and a negative refractive power having a convex surface facing the image side. The lens L ₂₃ having the meniscus shape corrects the negative spherical aberration generated in the A ₂ lens group and the sagittal flare from the middle of the screen to the periphery. Particularly, the lens L ₂₂ corrects the negative spherical aberration and the halo aberration generated in the A ₂ lens group, and the lenses L ₂₁ and L ₂₃ correct the sagittal flare around the screen.

When the second lens group B is constructed as described above, the principal ray of the off-axis rays causes overcorrection of the light flux on the upper side, which causes outward chromatic aberration. Therefore, the third lens unit C has a positive refractive power meniscus lens L ₃₁ having a convex surface facing the image side, a lens L ₃₂ having convex lens surfaces on both sides, and at least two positive refractive power meniscus lenses. By constructing L ₃₃ and L ₃₄ , the outward coma aberration generated in the second lens group and the field curvature and distortion aberration from the middle of the screen to the periphery are corrected in a well-balanced manner.

This image forming system functions sufficiently by satisfying the above-mentioned conditions, but it is preferable that the following conditions are satisfied in order to further improve the condition.

The first, second and third lens groups A,
The focal lengths of B and C are f ₁ , f ₂ and f ₃ , respectively, and A ₁
The focal lengths of the lens group and the A ₂ lens group are f ₁₁ ,
f ₁₂ and the focal length of the lens L ₁₁₁ is f ₁₁₁ , 1.9 <| f ₁ / f ₂ | <3.7 (7) 0.8 <| f ₂ / f ₃ | <1.2 ··· (8) 1.1 <| f ₁₁ / f ₁₂ | <2.3 ··· (9) 1.4 <f ₁₁₁ / f ₁₁ | <2.2 ··· (10) It is to satisfy the various conditions.

Conditions (7) and (8) are for properly correcting the field curvature of the entire screen by appropriately setting the refractive power of each lens group as one of the basics of lens performance, and the lower limit is set. When the value exceeds this value, the Petzval sum becomes large and the image surface is undercorrected. When the value exceeds the upper limit, the field curvature is overcorrected, and it becomes difficult to satisfactorily correct the aberration of the entire screen.

The condition (9) is the condition of the refractive power arrangements of the conditions (7) and (8), and the distortion correction by the A _1st lens unit and the inward coma and halo aberrations by the A ₂ lens unit are performed. This is for correcting and reducing the field curvature of the entire screen to achieve high resolution. If the lower limit of the condition (9) is exceeded, the field curvature will be undercorrected, and if the upper limit is exceeded, the field curvature will be overcorrected.

The condition (10) is for appropriately setting the sharing of the negative refracting power with respect to the object-side lens L ₁₁₁ of the A ₁ lens unit having the negative refracting power, and correcting the distortion satisfactorily. If the lower limit of the condition (10) is exceeded, the distortion will be undercorrected, and if the upper limit is exceeded, the distortion will be overcorrected.

In this image forming system, the lens L ₁₂₂ may have a convex surface on both lens surfaces, or may have a meniscus shape with the convex surface facing the object side.

In the present imaging system, if the _first lens unit A ₁ is composed of three or more meniscus lenses each having a convex surface facing the object side and having a negative refracting power, the sharing of the refracting power of each lens is reduced and the coma aberration is reduced. Is less likely to occur, and the influence of other various aberrations is also small, which is preferable.

If the lens L ₃₃ and the lens L ₃₄ of the third lens group are divided into three or more lenses to reduce the load of the refracting power of each lens, the coma aberration and the field curvature can be corrected more favorably over the entire screen. It is possible to achieve higher resolution.

As described above, according to the present imaging system, a high-performance projection lens having high resolution can be achieved in the projection exposure apparatus.

Next, numerical values of Numerical Examples 6 to 10 of the present imaging system which are not directly related to the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap in order from the object side, and Ni is the glass of the i-th lens in order from the object side. Is the refractive index. The glass material SIO ₂ is fused silica and has a refractive index of 1.521130 at a wavelength of 248.5 nm. In the numerical example, the projection magnification is 1/10, NA = 0.35, screen range 10
It is × 10.

[0059]

[Outside 6]

[0060]

[Outside 7]

[0061]

[Outside 8]

[0062]

[Outside 9]

[0063]

[Outside 10] 9 to 13 show various aberrations of Numerical Examples 6 to 10 above. In the figure, Y is the image height, M is the meridional image plane, and S is
Is the sagittal image plane.

A common point of Numerical Examples 1 to 10 described above is that a cemented lens for chromatic aberration correction is not included. Since this uses light from a single wavelength or an excimer laser having a very narrow wavelength width, it has such characteristics.

[0065]

According to the present invention, a suitable element manufacturing method and exposure apparatus can be achieved when an excimer laser is used as a light source for illuminating an original plate on which a pattern such as a mask and a reticle is formed. .

[Brief description of drawings]

FIG. 1 is a schematic view of an embodiment of the present invention.

FIG. 2 is a lens cross-sectional view of an image forming optical system according to the present invention.

FIG. 3 is a diagram showing various types of aberration in Numerical Example 1 of the imaging optical system according to the present invention.

FIG. 4 is a diagram showing various aberrations of Numerical example 2 of the imaging optical system according to the present invention.

FIG. 5 is a diagram showing various aberrations of Numerical Example 3 of the imaging optical system according to the present invention.

FIG. 6 is a diagram showing various types of aberration in Numerical Example 4 of the imaging optical system according to the present invention.

FIG. 7 is a diagram showing various types of aberration in Numerical example 5 of the imaging optical system according to the present invention.

FIG. 8 is a lens sectional view of an image forming optical system according to the present invention.

FIG. 9 is a diagram showing various types of aberration in the numerical example 6 of the imaging optical system according to the present invention.

FIG. 10 is a diagram showing various types of aberration in Numerical Example 7 of the imaging optical system according to the present invention.

FIG. 11 is a diagram of various types of aberration of Numerical example 8 of the imaging optical system according to the present invention.

FIG. 12 is a diagram showing various types of aberration in Numerical Example 9 of the imaging optical system according to the present invention.

FIG. 13 is a numerical example 10 of an imaging optical system according to the present invention.
Aberration diagrams

[Explanation of symbols]

 1 Excimer Laser 2 Illumination System 3 Imaging Optical System 4 Support 5 Wafer Chuck 6 XY Step Stage M Original Plate W Wafer Y Image Height M Meridional Image Surface S Sagittal Image Surface

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03F 7/20 521

Claims (4)

[Claims] 1. A device manufacturing method for manufacturing a device by illuminating a pattern with light from an excimer laser and projecting the pattern onto a substrate to be exposed through a projection lens system, wherein the projection lens system comprises a plurality of glass materials. And illuminating the pattern by narrowing the wavelength width of the light from the excimer laser, and arranging all of the plurality of lens elements constituting the projection lens system as a single lens. 2. The element manufacturing method according to claim 1, wherein the plurality of kinds of glass materials constituting the projection lens system are quartz and fluorite. 3. An exposure apparatus which illuminates a pattern of a mask with light from an excimer laser and projects the pattern of the mask onto a wafer through a projection lens system, wherein the projection lens system is composed of plural kinds of glass materials. An exposure apparatus characterized in that all of the plurality of lens elements constituting the projection lens system are composed of a single lens, and have means for narrowing the wavelength width of the light from the excimer laser. 4. The exposure apparatus according to claim 3, wherein the plurality of kinds of glass materials constituting the projection lens system are quartz and fluorite.