JP2001100018A - Optical device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable an optical device to be used in a vacuum ultraviolet region of <=200 nm wavelength. SOLUTION: (a) A substrate composed of fluorite is used as a substrate 11. Thereon an i-line negative photoresist is coated using a resist coating device. Succeedingly a pattern of the first chromium mask 12 is reduced baked to it using an i-line stepper. Subsequently it is subjected to a specified resist developing treatment so as to form a resist pattern 13 corresponding to the mask 12. (b) A CaF2 film 14 is film formed on the substrate 11 and the resist pattern 13 using a vacuum deposition device. Subsequently the resist pattern 13 is removed and ashing is carried out. (c) A CaF2 pattern 15 is formed. (d) Then a diffraction optical element 18 having a four-step outermost ring band is prepared by similarly laminating more CaF2 films using the second and third chromium mask 16, 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element which can be effectively used as an optical system for ultraviolet light, visible light, infrared light, especially for deep ultraviolet light and vacuum ultraviolet light in an exposure apparatus, a photographing apparatus, a lighting apparatus and the like. The present invention relates to an element manufacturing method suitable for manufacturing this type of element.

[0002]

2. Description of the Related Art Hitherto, a diffraction grating has been used as a spectral element of a spectroscope, and its shape is so-called a blazed type having a sawtooth shape, and some have a diffraction efficiency of up to 100%. In recent years, a binary optics (BO) element having a step-like shape, that is, a binary shape, has attracted attention as an optical element utilizing diffraction, and is called a BO lens and has an achromatic effect and an aspherical effect. Therefore, there is great expectation for the development of new optical systems.

A lens optical system for photographing with visible light, such as a general steel camera, can be manufactured by a molding method of plastic and glass by molding using a metal mold. However, in order to apply it to short-wavelength light such as ultraviolet light, UV transparency and finer processing and accuracy are required. At present, techniques such as mold processing, molding, and lens materials are required. Not established. In addition, the required specifications for a BO lens applied to a light beam having a short wavelength such as ultraviolet light greatly exceed the current blazed type processing limit, that is, the cutting processing limit.

The use of a photolithography process, which is a processing method for manufacturing semiconductors, has enabled a certain degree of fine processing with high precision. For this reason, a BO lens applicable to ultraviolet light and far ultraviolet light uses quartz and ultraviolet light for semiconductor production, and i-line (λ = 365n) is used for exposure printing.
m) stepper for dry etching, parallel plate type R for dry etching
By using an IE apparatus and using a photolithography technique and a dry etching technique, an eight-stage diffractive optical element can be manufactured.

[0005]

Conventionally, a diffractive optical element is manufactured by directly processing a quartz substrate. ArF (λ = 194 nm) and KrF (λ = 248 n) are formed on a quartz substrate.
Irradiation of high-energy laser light such as m) causes a problem of causing contraction. Therefore, fluorite has attracted attention as a substrate material instead of quartz. Further, the wavelength λ = 2
Photolithography technology has begun to be used in the vacuum ultraviolet region of 00 nm or less, and as a glass material constituting an optical system that can use this wavelength, quartz has insufficient performance, and is the only glass material that can be used instead of quartz It is fluorite.

However, fluorite has difficulty in processing and handling as a problem, and it is difficult to perform dry etching processing which was possible with quartz.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an optical element using a fluorinated compound such as fluorite having a fine structure and a method for manufacturing the optical element.

[0008]

According to the first aspect of the present invention, there is provided an optical element having a fine structure formed on a substrate of a fluoride compound such as fluorite by a lift-off process. I do.

According to a second aspect of the present invention, in the optical element according to the first aspect, silicon oxide (S) is formed on the substrate by vapor deposition.
iO ₂₎ The optical element of claim 1, wherein the oxide compound or fluoride compound, characterized in that the formation of such.

According to a third aspect of the present invention, in the optical element according to the first or second aspect, the fluorinated compound is selected from the group consisting of calcium fluoride, magnesium fluoride, barium fluoride, aluminum fluoride, lithium fluoride and cryolite. It is a metal fluoride containing at least one.

According to a fourth aspect of the present invention, in the optical element according to the second aspect, the vapor deposition method is a thin film forming method such as resistance heating vacuum vapor deposition, ion beam vapor deposition, or sputter vapor deposition.

According to a fifth aspect of the present invention, in the optical element according to any one of the first to sixth aspects, antireflection films are provided on both surfaces of the substrate on which a binary shape is formed by repeating the lift-off process. I do.

According to a sixth aspect of the present invention, in the optical element according to any one of the first to fifth aspects, the fine structure is a diffraction grating having a stepped cross section.

According to a seventh aspect of the present invention, in the optical element according to any one of the first to fifth aspects, the fine structure is a layer having a spherical surface or an aspherical surface.

According to an eighth aspect of the present invention, there is provided an optical system, a lens structure, and a device, comprising the optical element according to any one of the first to seventh aspects.

According to a ninth aspect of the present invention, there is provided an exposure printing apparatus for manufacturing a semiconductor device, wherein the optical system of the eighth aspect is incorporated.

According to a tenth aspect of the present invention, there is provided a semiconductor device manufactured using the exposure printing apparatus for manufacturing a semiconductor according to the eighth aspect.

[0018] According to a eleventh aspect of the present invention, there is provided a method of manufacturing an optical element, comprising the steps of: forming a film of an inorganic substance in a gap between resin patterns provided on a substrate by thin film forming means; Removing the inorganic substance on the resin pattern by gasification, and forming a pattern with the inorganic substance formed in the gap.

According to a twelfth aspect of the invention, there is provided a method of manufacturing an optical element according to the eleventh aspect, further comprising a lift-off process for removing the pattern by dry etching.

According to a thirteenth aspect of the present invention, in the method of the eleventh or twelfth aspect, the material of the substrate is fluorite.

According to a fourteenth aspect of the present invention, there is provided a method of manufacturing an optical element according to the eleventh or twelfth aspect, wherein the surface of the substrate is disposed so as to face the direction of gravity.

According to a fifteenth aspect of the present invention, in the method of the eleventh or twelfth aspect, the resin pattern is a resist pattern, and the inorganic substance is metal fluoride.
The method includes a step of applying a resist on the substrate, a step of pattern exposure, a step of developing the resist, and a step of depositing a metal fluoride.

According to a sixteenth aspect of the present invention, in the fifteenth aspect, one of the metal fluoride thin film forming means is formed by resistance heating, sputtering, ion beam sputtering, evaporation such as CVD, or the like. There is a feature.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a perspective view of the BO lens 1, and FIG. 2 is a sectional view thereof. BO lens 1 with a diameter of 20 mm
Is designed on the assumption that a KrF laser beam having a wavelength of λ = 248 nm is used, and about 1800 ring zones are engraved, and each ring zone has a stepped BO shape with four steps. , Function as a diffraction grating.

FIG. 3 is a sectional view of a four-stage stepped BO lens 1 in units of an annular zone. For example, in the outermost annular zone, the width of each stage is 0.7 μm and the height is 0.7 μm. Is 0.145 μm
And the width of each ring zone is 2.8 μm and the height is 0.434.
μm.

FIG. 4 is a sectional view showing the fabrication of the diffractive optical element according to the first embodiment. The diffractive optical element is fabricated by using a lift-off process. First, as shown in FIG. 4A, a fluorite substrate having a diameter of 2 inches and a thickness of 2 mm was used as the substrate 11, and a resist coating apparatus (spinner) was used on the substrate 11 to form a film having a thickness of 0 mm. .8 μm i-line negative resist is applied. Subsequently, after the pattern of the first chromium mask 12 is reduced and baked using an i-line stepper, a prescribed resist development process is performed to produce a resist pattern 13 corresponding to the mask 12.

Next, as shown in FIG. 4B, after a CaF ₂ film 14 having a thickness of 0.145 μm is formed on the substrate 11 and the resist pattern 13 by using a vacuum deposition apparatus of a resistance heating method. This resist pattern 13 is formed using acetone.
Is removed and ashing is performed gently using oxygen plasma to form a CaF ₂ film pattern 1 as shown in FIG.
5 can be formed. Subsequently, as shown in FIG. 4D, the same steps are repeated using the second and third chromium masks 16 and 17, and a CaF2 film is further laminated to form the outermost ring of the diffractive optical element. 0.7μ width of each step of the band
Thus, a four-stage diffractive optical element 18 having a height m of 0.145 μm, a width of 2.8 μm per ring zone, and a height of 0.43 μm can be manufactured.

An MgF ₂ film may be formed in place of the CaF ₂ film 14, and furthermore, a metal fluoride such as BaF ₂ , aluminum fluoride (AlF ₂ ), LiF, and cryolite (NaAlF ₆ ) Can be produced by vapor-deposition. All of these diffractive optical elements thus obtained show good results.

As a second embodiment, as shown in FIG. 5, a 440 ° -thick LiF film 21 is laminated on the front surface of the diffractive optical element 18 and the back surface of the substrate 11 as an antireflection film by using a vacuum evaporation method. . Then, when the diffraction efficiency of this optical element is measured using KrF laser light, the diffraction efficiency is improved by 10% on average compared to the case where the antireflection film is not formed.

As a third embodiment, quartz is used for the substrate and an SiO ₂ film is used for the deposition material. In addition, the film forming apparatus includes R
An IE sputtering apparatus is used, and a mixed gas of argon and hydrogen is used as an etching gas. Then, the above-described lift-off process is repeated three times using three masks, whereby a four-stage diffractive optical element can be manufactured.

Further, an antireflection film having a film thickness of 43.mu.m is formed on the front surface and the back surface of the substrate of the diffractive optical element manufactured by the above method.
Four layers of an MgF ₂ film of 3 nm and an Al ₂ O ₃ film of a thickness of 36 nm are alternately laminated by a sputtering method. Then, when the diffraction efficiency of this optical element is measured by using a KrF laser beam, the diffraction efficiency is improved by 16% on average, compared with the case where the antireflection film is not formed.

FIG. 6 is a schematic diagram showing the fabrication of a diffractive optical element using dry lift-off in the fourth embodiment.
This dry lift-off method is suitable for processing a material that is sensitive to moisture such as metal fluoride. Moreover, it is a process suitable for brittle materials that have less ductility such as metal fluoride than materials having ductility such as pure metal. Further features of the dry lift-off method include dry development,
Total dry process by using non-aqueous resist,
That is, a total lift-off process can be realized.

First, as shown in FIG. 6 (a), a fluorite substrate 11 having a diameter of 2 inches and a thickness of 2 mm was used similarly to the first embodiment, and a 1 μm-thick i-line Is applied using a spinner. Subsequently, using a stepper for i-line to form the second stage of the diffractive optical element, the pattern of the first chromium mask 12 is reduced and baked on the photoresist on the substrate 11, and then subjected to processes such as development. A resist pattern 31 is formed. Next, FIG.
As shown in FIG.
An inorganic material of, for example, a CaF ₂ film 32 having a thickness of 0.145 μm is formed on the top 1, that is, in the gap between the resin patterns by using a resistance heating type evaporation apparatus. Then, using a dry etching apparatus (not shown), the substrate 1 is removed as shown in FIG.
Ashing is performed by using oxygen plasma to remove the resist pattern 31 formed on the substrate 1 and then ashed and gasified, thereby generating a CaF ₂ film pattern 33.

In this etching apparatus, the reaction chamber is divided into a plasma generation chamber and a reaction chamber (etching chamber), so that isotropic damageless etching can be performed. Further, in this reaction chamber, the surface of the substrate 11 is always placed downward so as to prevent the residue of the metal fluoride on the resist from which the sample is removed by ashing on the holder, and the surface of the substrate 11 is always directed downward. By performing treatment using plasma, the resist pattern 31 and the CaF ₂ film 32 on the resist pattern 31 are removed by ashing, whereby a CaF ₂ film pattern 33 of the CaF ₂ film 32 can be formed on the surface of the substrate 11. it can. Subsequently, as shown in FIG. 4D, the same dry lift-off process is repeatedly performed using the second and third masks, whereby a four-stage diffractive optical element can be manufactured.

Further, using the above-described process, a 0.8 μm-thick i-line photoresist is coated on a fluorite substrate using a spinner. Then, using a stepper for i-line, forming a second step of the diffractive optical element, reducing the pattern of the first chromium mask onto the photoresist on the substrate, and developing the resist pattern through processes such as development. Then, a CaF ₂ film having a thickness of 0.062 μm is formed on the resist pattern on the substrate by using a resistance heating type deposition apparatus. By ashing and removing the resist pattern and the CaF ₂ film on the resist pattern, a second-stage pattern can be formed, and the same dry lift-off process is repeated using the second to seventh masks. Thus, an eight-stage diffractive optical element can be manufactured.

The outermost annular zone of the diffractive optical element manufactured in this embodiment has a width of one step of 0.35 μm and a height of 0.062 μm. The width and height of the outermost annular zone, that is, the element unit, are 2.8 μm and 0.434 μm, respectively.

Further, a diffraction optical element having a diameter of 20 mm may be manufactured by using a BaF ₂ film instead of the CaF ₂ film 32.
First, using a spinner on a substrate, an i.
A line resist is formed. Then, after the pattern of the first mask is reduced and printed using an i-line stepper, a prescribed resist development process is performed to produce a resist pattern corresponding to the first mask. Next, a 0.145 μm-thick Ba film was
After the F ₂ film is formed and the resist is ashed and removed using oxygen plasma, the surface is lightly sputter-etched, whereby the second-stage BaF ₂ film pattern of the diffractive optical element can be formed. . Similarly, by repeating the same steps using the second and third masks, a BaF ₂ film can be laminated, and the width and height of each step of the outermost annular zone of the diffractive optical element are each 0%. 0.7 μm, 0.145 μm, and 2.8 μm and 0.43 μm, respectively.
A stepped diffractive optical element can be manufactured.

As a fifth embodiment, antireflection is applied to the front surface of the four-stage diffractive optical element manufactured by the dry lift-off method on the fluorite substrate 11 manufactured in the fourth embodiment and the back surface of the substrate 11. The thickness of the film is 440 using a vacuum evaporation method.
The LiF film of Å is formed. Then, using a KrF excimer laser beam, the diffraction efficiency of the diffractive optical element was measured,
Compared to the case where the antireflection film is not formed, the average is improved by 12%.

Further as an antireflection film, an Al ₂ O ₃ film of MgF ₂ film and the film thickness 360Å with a thickness of 434Å were laminated using the vacuum deposition method in place of the LiF film may be a multilayer of 4 layers . Then, this diffractive optical element is measured by using a KrF excimer laser beam, and the average is improved by 18% as compared with the case where the antireflection film is not formed.

FIG. 7 is a schematic diagram showing the fabrication of a diffractive optical element according to the sixth embodiment, and FIG. 7A is a sectional view of chrome masks 41, 42, and 43 used as the mask. First,
Using a mask 41 on the substrate 11, a resist pattern 44 is formed by photolithography, and then, as shown in FIG. 7B, an evaporation method is used on the fluorite substrate 11 and the resist pattern 44 by evaporation. Metal fluoride film 4
5 is formed to a height of 4/7 of a specified film thickness. Subsequently, as shown in FIG. 7C, the resist pattern 44 is removed by using a lift-off method, so that the metal fluoride pattern 46 is removed.
Can be formed. Further, a metal fluoride pattern 47 is formed by forming a metal fluoride film on the metal fluoride pattern 45 to a height of 2/7 of a specified thickness using the second mask 42 in the same manner. can do. Finally, using the mask 43, a metal fluoride film is formed on the metal fluoride patterns 45 and 46 so as to have a height of 1/7 of a specified film thickness, thereby forming a metal fluoride pattern 48 to form eight steps. Can be formed. In addition, n has shown the coefficient of height.

The diffraction optical element 49 having eight stages can also be formed by changing the order of the masks, that is, by using the masks in the order of the masks 43, 42 and 41 and using the same photolithography method and lift-off method by vapor deposition. Can be created.

As a seventh embodiment, the same step as in the first embodiment is performed, and a stepper is divided and exposed to a light having a diameter of 200 m.
m diffractive optical elements are manufactured. A high-performance semiconductor device is manufactured by reduction baking on a silicon substrate using a stepper with a KrF excimer laser as a light source equipped with a lens optical system incorporating the diffractive optical element and a series of semiconductor manufacturing processes. Can be. Also, Kr
In addition to the F excimer laser, an ArF excimer laser (wavelength 193 nm) and an F ₂ excimer laser (wavelength 157 n)
An optical element for m) is prepared, and this optical element is applied to a lens system to configure a stepper using the above-described excimer laser as a light source.

Next, a method for manufacturing a semiconductor device using a semiconductor exposure apparatus equipped with the diffractive optical element manufactured in the above embodiment will be described. FIG. 8 shows a flowchart of a manufacturing process of a semiconductor device such as a semiconductor chip such as an IC or an LSI, a liquid crystal panel or a CCD. First,
In step S1, the circuit of the semiconductor device is designed, and then in step S2, a mask is created using the EB lithography apparatus or the like on the circuit pattern designed in step S1. On the other hand, in step S3, a wafer is manufactured using a material such as silicon. Thereafter, in step S4 called a pre-process, using the mask and wafer prepared in steps S2 and S3, the mask is loaded into an exposure apparatus, and the mask is transported and chucked on a mask chuck.

Next, the wafer is loaded to detect misalignment, the wafer stage is driven to perform alignment, and exposure is performed when the alignment is matched.
After the exposure is completed, the wafer is stepped to the next shot, and a circuit is formed on the wafer by lithography. Further, in step S5 called a post-process, a semiconductor chip is formed using the wafer manufactured in step S4 through an assembly process such as dicing and bonding and a packaging process such as chip encapsulation. In step S6, the chiped semiconductor device undergoes inspections such as an operation check test and a durability test. The semiconductor device is completed through such a series of steps, and the step S
Go to 7 and ship.

FIG. 9 is a flowchart showing the detailed manufacturing process of the wafer manufacturing in step S3 in FIG. First, in step S11, the wafer surface is oxidized. Subsequently, in step S12, an insulating film is formed on the wafer surface by the CVD method.
Is formed by an evaporation method. Further, the process proceeds to step S14, where ions are implanted into the wafer, and subsequently, in step S15, a photosensitive agent is applied on the wafer. In step S16, the circuit pattern of the mask is printed on the photosensitive agent on the wafer by the semiconductor exposure apparatus.

In step S17, step S16
Developing the photosensitive agent on the exposed wafer. Furthermore,
In step S18, portions other than the resist image developed in step S17 are etched. Thereafter, in step S19, the unnecessary resist after the etching is removed. Furthermore, by repeating these series of steps, multiple circuit patterns can be formed on the wafer.

By using the manufacturing method of this embodiment, it is possible to cope with mass production of a highly integrated semiconductor device which has been difficult to manufacture conventionally.

[0048]

As described above, according to the optical element of the present invention, an optical element of metal fluoride such as fluorite having a fine structure such as a diffraction grating or a spherical or aspherical surface can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view of a diffractive optical element.

FIG. 2 is a sectional view of a diffractive optical element.

FIG. 3 is an enlarged sectional view of a diffractive optical element.

FIG. 4 is a schematic drawing of the production of the diffractive optical element in the first embodiment.

FIG. 5 is a sectional view of a substrate according to a second embodiment.

FIG. 6 is a sectional view of a diffractive optical element according to a fourth embodiment.

FIG. 7 is a sectional view of a diffractive optical element according to a sixth embodiment.

FIG. 8 is a manufacturing flowchart of a semiconductor device.

FIG. 9 is a detailed flowchart of wafer manufacturing.

[Explanation of symbols]

11 substrate 12, 16, 17 a mask 13, 31 resist pattern 14, 32 CaF ₂ film 15, 33 CaF ₂ film pattern 18 diffractive optical element 21 LiF film

Continued on the front page F-term (reference) 2H049 AA04 AA16 AA31 AA44 AA45 AA48 AA55 AA63 2K009 AA04 AA07 BB04 CC03 CC06 DD03

Claims (16)

[Claims] 1. An optical element wherein a fine structure is formed on a substrate of a fluorinated compound such as fluorite by a lift-off process. 2. The optical element according to claim 1, wherein an oxide compound such as silicon oxide (SiO ₂ ) or a fluoride compound is formed on the substrate by vapor deposition. 3. The fluorinated compound is calcium fluoride,
The optical element according to claim 1, wherein the optical element is a metal fluoride containing at least one of magnesium fluoride, barium fluoride, aluminum fluoride, lithium fluoride, and cryolite. 4. The optical element according to claim 2, wherein said vapor deposition method is a thin film forming method such as resistance heating type vacuum vapor deposition, ion beam vapor deposition, and sputter vapor deposition. 5. The optical element according to claim 1, wherein antireflection films are provided on both surfaces of the substrate having a binary shape formed by repeating the lift-off process. 6. The optical element according to claim 1, wherein the fine structure is a diffraction grating having a stepped cross section. 7. The optical element according to claim 1, wherein the fine structure is a layer having a spherical surface or an aspherical surface. 8. An optical system, a lens structure and an apparatus, comprising an optical element according to claim 1. Description: 9. An exposure printing apparatus for manufacturing a semiconductor, wherein the optical system according to claim 8 is incorporated. 10. A semiconductor device manufactured by using the exposure printing apparatus for manufacturing a semiconductor according to claim 8. 11. A step of forming an inorganic substance in a gap between resin patterns provided on a substrate by a thin film forming means, and insulating and gasifying the resin pattern by oxygen plasma to form the inorganic substance on the resin pattern. Removing the substance; and forming a pattern with the inorganic substance formed in the gap. 12. The method according to claim 11, further comprising a lift-off process for removing the pattern by dry etching. 13. The method according to claim 11, wherein a material of the substrate is fluorite. 14. The method for manufacturing an optical element according to claim 11, wherein the surface of the substrate is set so as to face the direction of gravity. 15. A step of applying a resist on the substrate, a step of pattern exposure, a step of developing a resist, and a step of applying the metal fluoride to the resist pattern as a resist pattern and the inorganic substance as a metal fluoride. The method for producing an optical element according to claim 11, further comprising a step of vapor deposition. 16. One of the metal fluoride thin film forming means is resistance heating, sputtering, ion beam sputtering, CV
The method for manufacturing an optical element according to claim 15, wherein the method is vapor deposition of D or the like.