1. Field of the Invention
The present invention relates to an exposure apparatus, and in particular to an exposure apparatus having a focal point detection function.
2. Description of the Background Art
In a conventional exposure apparatus, the focal point at the time of exposure is detected by guiding a detection light at a wide angle to a surface of a substrate constituting an object to be measured and thus increasing a reflectivity of the uppermost surface of the substrate. A light reflected from the substrate is detected by a light detector, and a position of the reflected light is measured thereby to detect the focal point at the time of exposure.
In recent years, a new exposure technique called the liquid immersion lithography has come to be closely watched. The liquid immersion lithography is a technique of making exposure with a liquid filled between a projection lens of a stepper and a wafer.
In the liquid immersion lithography, the liquid exists on a resist, and therefore it is difficult to detect the focal point at the time of exposure in real time in a method similar to the aforementioned case. In view of this, there has been proposed a method of detecting the focal point of the detection light in the air on another wafer stage and use the resultant data.
An exposure method using the conventional exposure apparatus is disclosed in Japanese Patent Laying-Open Nos. 09-036017, 2004-207709 and 2005-099648, and WO00/58761.
A non-polarized light is often employed as the detection light radiated on the substrate surface for detecting the focal point at the time of exposure. The detection light is radiated at a wide angle to increase the reflectivity of the detection light on the uppermost surface of the substrate as described above. Part of the detection light, however, enters films formed on the substrate and interferes by multiplex reflection in each thin film. As a result, the detection light becomes the reflected light covering a broad range of height (detection position) and width including the light reflected from the films lower than the uppermost surface of the substrate. For this reason, a position lower than the uppermost surface of the substrate may be detected on the one hand, and since the detection light is periodically changed due to the effect of multiplex reflection in the underlying thin films, a detection error may occur on the other hand. This problem tends to become conspicuous in the liquid immersion lithography. Nevertheless, a similar problem is encountered inherently in the normal exposure in the air.
As described above, the problem of the detection error of the focal point at the time of exposure is considered to become conspicuous for the liquid immersion lithography. The reason why this problem becomes conspicuous for the liquid immersion lithography is explained below.
In the liquid immersion lithography, the liquid exists on the resist at the time of exposure, and therefore the detection light for detecting the focal point passes through the liquid. In view of the fact that a refractive index of the light entering the liquid is larger than that of the light entering the air, however, the reflectivity of the detection light on the resist surface for the liquid immersion lithography is reduced as compared with the value for normal exposure.
Now, the relation between a difference of refractive indexes among a plurality of media and the reflectivity at a surface boundary between the media is explained.
According to the Fresnel formulae, the amplitude reflectivity, at a single surface boundary, of a light entering a second medium from a first medium at an angle of θ is given by Equations (1) and (2) described below respectively for an s-polarized light and a p-polarized light, for example. In Equations (1) and (2), n1 and n2 indicate refractive indexes of the first and second media, respectively. A light intensity reflectivity is expressed as a square of the amplitude reflectivity.
Equations (1) and (2) show that the larger the difference between the refractive index (n1) of the first medium and the refractive index (n2) of the second medium is, the higher the reflectivity at the single surface boundary. In a case where the difference is reduced between the refractive index on an exposure medium constituted of a liquid and the refractive index on the resist as in the liquid immersion lithography, therefore, it becomes difficult to increase the reflectivity of the uppermost surface of the substrate (the surface boundary between the exposure medium and the resist, for example). As a result, a greater amount of detection light intrudes into the resist at the time of detecting the focal point, and the detection light interferes by multiplex reflection on internal reflection surfaces. As compared with the normal exposure, therefore, detection accuracy of the focal point is liable to be deteriorated.
The present invention has been achieved to solve these problems and an object thereof is to provide an exposure apparatus capable of improving detection accuracy of a focal point for exposure.
According to the present invention, there is provided an exposure apparatus including an illumination optical system having a first light source for emitting an exposure light, a projection optical system for guiding the exposure light to a substrate, a second light source for emitting a detection light for detecting a focal point at a time of exposure, a polarizer capable of polarizing the detection light emitted from the second light source into a specified polarized light, and a light detector for detecting the detection light polarized into the specified polarized light by the polarizer.
The exposure apparatus according to the present invention includes the polarizer described above, and therefore can polarize the detection light for detecting the focal point into a specified polarized light. By irradiating the substrate with the detection light polarized into the specified polarized light as described above, a reflectivity in a specified surface boundary can be secured while suppressing the reflectivity at a low level in the surface boundaries other than the specified surface boundary in a film structure formed on the substrate. As a result, an effect of the light reflected from the surface boundaries other than the specified surface boundary can be suppressed, and detection accuracy of the focal point at the time of exposure can be improved.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
FIGS. 28 to 35 are sectional views showing a first to eighth steps of a semiconductor device fabrication method.
Embodiments of the present invention are described below with reference to FIGS. 1 to 35.
The use of liquid immersion lithography unit 20 as in the first embodiment can meet the requirements for fabrication of a semiconductor device with the design rule of, for example, not more than 45 nm, and makes it possible to form a resist pattern of about not more than 130 nm. In the first embodiment, an application of the invention to a liquid immersion lithography unit. Nevertheless, the present invention is applicable also to an exposure apparatus other than the liquid immersion lithography unit.
As shown in
Polarizer 30 may be disposed between detection light source 29 and substrate 1 as shown in
In the following, detailed description will be given on the structure of
In the case where polarizer 30 is disposed on a path of the light to be radiated on the substrate, and radiates the specified polarized light on substrate 1 (in the case of
It is to be noted that the term “light resistance” used herein refers to resistance to deterioration of a polarizer such as a reduction in transmittance of the polarizer due to a defect within the polarizer caused by light energy or heat, or due to adhesion of a contamination such as ammonium sulfate ((NH4)2SO4) in the air to the polarizer.
Exposure light source 23 can be formed of, for example, a pulse laser such as an ArF excimer laser having a wavelength of about 193 nm, a KrF excimer laser having a wavelength of about 248 nm or a F2 excimer laser having a wavelength of about 157 nm.
Illumination optical system 22 is for guiding the light from exposure light source 23 to photomask 37. Illumination optical system 22 according to this embodiment includes a beam forming system such as a beam expander having a plurality of cylindrical lenses, a focusing optical system having a zoom lens system, a polarization control means having a polarizer, an optical integrator having various mirrors such as a bent mirror and a fly-eye lens, and various optical elements such as an aperture diaphragm for defining the illumination area on photomask 37, a focusing lens and an imaging lens.
A pattern to be transferred to resist film 2 constituting a photosensitive film coated on substrate 1 is formed on photomask 37. Photomask 37 is driven while being held on a mask stage (not shown) through a mask holder (not shown). The light emitted from photomask 37 is projected on resist film 2 on substrate 1 through projection optical system 24.
Projection optical system 24 has the function of forming an image of the diffracted light transmitted through photomask 37 on resist film 2. Projection optical system 24 may include a plurality of lens elements having a lens 24a, a concave mirror and a diffraction optical element.
The immersion liquid supply unit includes an immersion liquid source (not shown) for supplying an immersion liquid 27 such as water, a deaeration unit 25 for removing the gas from immersion liquid 27, a supply nozzle 26 arranged to reach a point under projection optical system 24 to supply immersion liquid 27 onto resist film 2, and a discharge tube 28 extending outward from under projection optical system 24 for discharging immersion liquid 27.
Stage 21 is driven by a drive mechanism not shown while holding substrate 1 to move substrate 1 to the desired position. Detection light source 29 may be any light source capable of emitting the non-polarized light. A solid light source such as a light-emitting diode is an example. Also, the detection light having at least two types of waveform can be emitted by using a plurality of light-emitting diodes.
The detection light emitted from detection light source 29 preferably has an exposure wavelength in the range not sensitizing the resist. For selective reflection on the resist surface, on the other hand, the detection light is desirably radiated at an angle as wide as possible (say, 80° to 88°). The detection light, which may have a single wavelength, can have two or more wavelengths in the range not sensitizing at least the resist in order to reduce the interference. Detection light source 29 may be a lamp, a semiconductor laser, etc. as well as the light-emitting diode described above.
The detection light emitted from detection light source 29 is polarized into the desired polarized light through polarizer 30. Specifically, polarizer 30 converts the polarization component of the detection light into the s-polarized light, the p-polarized light or the linearly polarized light of 45 degrees including the s-polarized light and the p-polarized light.
A method of forming a polarized light is explained below. The method of forming the polarized light includes a method utilizing the birefringence of an optically anisotropic crystal or a method of utilizing the Brewster angle based on the polarization direction dependency of the diagonal incident light. Nevertheless, a simple method of forming the polarized light uses a polarizer.
Polarizer 30 having the structure shown in
As shown in
The polarization of the light transmitted through polarizer 30 is dependent on the direction of polarizer 30. By rotating polarizer 30 using drive unit 31 described above, therefore, the s-polarized light, the p-polarized light or the linearly polarized light of 45 degrees can be acquired freely. In the case where the polarized light is obtained from the detection light reflected from the substrate, polarizer 30 is disposed in front of light detector 32 to introduce only a specified polarization component into light detector 32. Although the s-polarized light and the p-polarized light reflect at respective different positions as shown in
Light detector 32 is an element for receiving the detection light radiated and reflected on substrate 1, and includes a photodiode such as CCD (charge-coupled device) and optical elements such as various lenses. Also, a drive unit (not shown) may be provided which drives and moves light detector 32 in operatively interlocked relation with stage 21.
Exposure apparatus 20 includes an arithmetic processing unit 33 connected with light detector 32 to calculate the focal point using the amplitude and phase difference of the reflected detection light and the optical constant of the film formed on substrate 1. Arithmetic processing unit 33 typically has a storage unit (not shown) for storing the various information including the optical constant of the film formed on substrate 1.
Though not shown in
Next, a semiconductor device fabrication method including the exposure step using exposure apparatus 20 having the above-mentioned configuration is explained with reference to FIGS. 28 to 35. In the description that follows, an explanation is made about a method of fabricating the n-channel MOS (metal oxide semiconductor) transistor included in the semiconductor device.
A well is formed at the main surface of substrate (p-type silicon substrate, for example) 1 by introducing predetermined impurities, and an element isolation structure is formed in such a manner as to define an element forming area. In a case where STI (shallow trench isolation) is employed as an element isolation structure, trenches are formed by etching the main surface of the substrate, and insulating films such as silicon oxide films are embedded in the trenches. Also, boron for adjusting the threshold voltage of the MOS transistor is ion-implanted in the area of forming the MOS transistor with the injection energy of 30 to 60 KeV and the doping amount of not more than 2×1012 cm−2, for example.
Next, as shown in
Next, as shown in
Next, the focal point is detected by detecting the height of upper layer resist film 12. In detecting the focal point, substrate 1 coated with each resist film is arranged on stage 21 shown in
A method of detecting the focal point at the time of exposure is explained in detail below, As described above, the detection light passed through polarizer 30 is radiated on upper layer resist film 12. This detection light is substantially configured of only the polarization component. More specifically, upper layer resist film 12 is irradiated with the s-polarized light, the p-polarized light or the linearly polarized light of 45 degrees including the s-polarized light and the p-polarized light in the ratio of 1 to 1. By radiating the polarization component on upper layer resist film 12 in this way, the upper surface boundary or the lower surface boundary of upper layer resist film 12 can be selectively grasped. Also in a case where the thickness of upper layer resist film 12 or the base structure of upper layer resist film 12 undergoes a change, the variation in the focal point measurement position can be effectively suppressed.
The reason is explained below with reference to FIGS. 5 to 18.
As shown in
In view of this, the reflectivity of the light entering the layers lower than resist film 2 has also been studied, of which the result is explained below.
FIGS. 7 to 9 show the incidence angle dependency of reflectivity of each polarized light in the surface boundary between the resist and the anti-reflection film, the incidence angle dependency of reflectivity of each polarized light in the surface boundary between the anti-reflection film and the silicon oxide film and the incidence angle dependency of reflectivity of each polarized light in the surface boundary between the silicon oxide film and the substrate at the time of conducting liquid immersion lithography.
As understood from FIGS. 7 to 9, the reflectivity of the s-polarized light is highest for all the surface boundaries. Specifically, it is understood that the use of the s-polarized light increases the reflectivity in each surface boundary of the light transmitted from the upper layer. Also, it is understood that the reflectivity of the non-polarized light transmitted from the upper layer, as compared with that of the p-polarized light, is higher in each surface boundary.
The reflectivity of the p-polarized light, on the other hand, is lowest for every surface boundary. Especially, the reflectivity of the p-polarized light in the surface boundary between substrate 1 and silicon oxide film 3, as shown in
As described above, the reflectivity value of the s-polarized light on the resist surface is highest. As compared with the high reflectivity of the s-polarized light in the surface boundaries of the lower layers, however, the reflectivity of the p-polarized light, though lower than that of the s-polarized light on the resist surface, is lowest in the surface boundaries of the lower layers. In view of this, the resist surface is considered to be grasped with highest accuracy by using the p-polarized light as the detection light.
The present inventor has made calculations to confirm the contents described above, the result of which is explained below. Specifically, the reflectivity on the surface of the resist film 3 with the incidence angle of 86 degrees was calculated by changing the thickness of the resist film 2 and the thickness of the silicon oxide film 3 while at the same time taking the light interference in the thin films of the lower layers into consideration in the film structure shown in
As understood in FIGS. 10 to 12, the variation of reflectivity the s-polarized light on the resist surface is largest with the thickness change of resist film 2 and silicon oxide film 3 constituting a lower layer. This indicates that the s-polarized light is most liable to be affected by the light reflected from the surface boundaries of the lower layers.
It is understood from
The result of the calculations described above is shown in Table 1 below.
The result shown in Table 1 above indicates that in a case where the film structure shown in
The present inventor also has studied the case in which a film structure including a polysilicon film is formed in the layers lower than resist film 2, the result of which is explained below with reference to FIGS. 13 to 18.
As shown in
As understood from
Also with the film structure shown in
As shown in FIGS. 16 to 18, in a case where polysilicon film 5 is formed under resist film 2, the reflectivity variation of the s-polarized light on the resist surface is largest with the thickness change of resist film 2 and the underlying silicon oxide film 3. The s-polarized light, therefore, is considered most liable to be affected by the reflected light from the lower layer surface boundaries.
As shown in
The result of this calculation is shown in Table 2 below.
The result shown in Table 2 indicates that in a case where the film structure shown in
Depending on the film structure formed on the substrate, the s-polarized light or the linear polarized light of 45 degrees including the s-polarized light and the p-polarized in the ratio of 1 to 1 can also be used. Specifically, according to the present invention, an appropriate polarized light can be selected in accordance with the configuration of the films under the resist film. By selecting an appropriate polarized light in this way, as long as the incidence angle of the detection light remains the same, the upper and the lower surface boundaries of the resist can be grasped in more stable fashion with higher accuracy than in a case where the non-polarized light is used as the detection light. As a result, the incidence angle of the detection light can be reduced, thereby improving the design freedom of the exposure apparatus.
Also, in a case where the detection light is detected based on the light intensity alone by the light detector, the linearly polarized light of 45° containing the s-polarized light and the p-polarized light in the ratio of 1 to 1 and the non-polarized light are considered to give the same result. Further, in a structure capable of suppressing the reflection from the lower layers, the s-polarized light or the non-polarized light may be effectively used. In view of this, drive unit 31 of exposure apparatus 20 shown in
After detecting the focal point using the detection light as described above, the exposure light is emitted from exposure light source 23 along the direction of optical axis 34 and radiated on photomask 37 through illumination optical system 22. The light transmitted through photomask 37 is radiated on upper layer resist film 12 through the projection optical system and immersion liquid 27. As a result, upper layer resist film 12 can be sensitized, and the pattern formed on photomask 37 can be transferred to upper layer resist film 12. After that, the heat treatment is conducted and the development process is executed with an alkali developer (tetra-ammonium hydroxide 2.38 wt %). As a result, exposure can be carried out with the focal point accurately controlled, and as shown in
With this resist pattern 12a as a mask, as shown in
Using each pattern obtained in the manner described above as an etching mask, conductive film 8 is dry etched, and as shown in
Next, as shown in
After that, an insulating film of silicon oxide or the like is formed by CVD in such a manner as to cover gate electrode 8a, and the insulating film is subjected to anisotropic etching. As a result, a sidewall insulating film 14 is formed on the sidewall of gate electrode 8a. At the same time, insulating film 7 is also etched and a gate insulating film 7a formed.
With sidewall insulating film 14 and gate electrode 8a as a mask, predetermined n-type impurities are implanted in substrate 1 in self-aligned fashion for sidewall insulating film 14 and gate electrode 8a. For example, arsenic (As) are ion-implanted with the injection energy of 30 to 50 KeV and the doping amount of between 1×1015 cm−2 and 5×1015 cm−2 inclusive. As a result, an n-type high-concentration impurities region 13b can be formed.
Next, as shown in
The surface height of resist film 17 is detected in the same manner as upper layer resist film 12 to determine the focal point at the time of exposure. After that, the exposure light is radiated to sensitize resist film 17, and after heat treatment, the development process executed with an alkali developer (tetra-ammonium hydroxide 2.38 wt %). With the resultant resist pattern as a mask, layer insulating film 15 is dry etched by alkyl fluoride gas such as CF4, C2F8 or CHF3, while at the same time separating resist film 17. Thus, contact holes 18 can be formed.
In each contact hole 18, a conductive film 19 is formed by CVD or sputtering. Conductive film 19 may be a polysilicon film doped with impurities, a metal film having a high melting point such as a tungsten (W) film, a titanium nitride (TiN) film or a copper (Cu) film. By patterning conductive film 19, an electrode can be formed as shown in
In forming a device of multilayer wiring structure, a layer insulating film is formed in such a manner as to cover conductive film 19 in the state shown in
In the embodiment described above, the three-layer resist method is used to form gate electrode 8a and the single resist layer method to form contact holes 18. This is only an example, and an appropriate one can be selected from the single resist layer method, the multilayer resist method, the hard mask method and the two resist layer method using a silicon-contained photosensitive resist.
Next, a second embodiment of the invention is explained with reference to FIGS. 19 to 24.
In the first embodiment described above, an anti-reflection film such as BARC having the ability to absorb the focal point detection light (450 nm to 850 nm) is used for the layer lower than the resist film. In the second embodiment, on the other hand, an upper layer film (top coating material) higher in refractive index than the resist film is formed on the resist film. This upper layer film, being alkali soluble and capable of absorbing the focal point detection light (450 nm to 850 nm), can be formed of a film high in refractive index. The other components are basically similar to the corresponding ones of the first embodiment.
Now, an example of the material of upper layer film 6 is explained. Upper layer film 6 can be a film having a main component of such a material as an alkali soluble polymer which is formed by copolymerizing a polymerizable monomer (except for a non-polar polymerizable monomer) containing an alkali-reactive group in the amount of 40 to 100% of the total amount of the polymerizable monomer and the non-polar polymerizable monomer and in which the main chain of the resultant polymer is modified, by ester bond, ether bond or amide bond, with a pigment capable of absorbing the long wavelength light in the range of 450 nm to 850 nm. More specifically, the upper layer film 6 has, as a main component, an alkali soluble polymer which is obtained by copolymerizing a polymerizable monomer (except for non-polar polymerizable monomer) containing the carbonic acid group, phenol group, alcohol fluoride group, sulfonic acid group or maleic anhydride group in the proportion of 40 to 100% of the total amount of the polymerizable monomer and the non-polar polymerizable monomer and in which the main chain of the resultant polymer is modified, by ester bond, ether bond or amide bond, with a pigment having parents in azo group, quinone group, cyanine group, phthalocyanine group or indigo group capable of absorbing the long wavelength light in the range of 450 nm to 850 nm. In other words, the main component of upper layer film 6 is an alkali soluble polymer produced by polymerizing a polymerizable monomer containing the alcohol fluoride group, and the main chain of this polymer is modified, by ester bond, with a pigment having parents in the indigo group capable of absorbing the long wavelength light in the range of 450 nm to 850 nm.
By forming upper layer film 6 on resist film 2 as described above, the reflectivity of the surface of upper layer film 6 can be increased, and the surface boundary between upper layer film 6 and immersion liquid 27 can be grasped highly accurately. Like in the first embodiment, therefore, the focal point can be detected in real time at the time of exposure.
This inventor has studied the incidence angle dependency of the reflectivity of each polarized light in the upper and lower surface boundaries of upper layer film 6 at the time of liquid immersion lithography with water, the result of which is explained below.
As shown in
As shown in
The foregoing fact shows that also in the second embodiment, as far as the reflectivity on the surface of the upper layer film is concerned, that of the s-polarized light is highest. In view of the fact that the reflectivity of the s-polarized light is also high in the surface boundary with the lower layers, however, a specific surface boundary (surface boundary between the upper layer film and water) may be most accurately grasped by use of the p-polarized light as the detection light.
Accordingly, the present inventor has made the calculations to confirm the contents described above, and the result is explained below.
Specifically, the reflectivity on the surface of upper layer film 6 was calculated at the incidence angle of 86°, as in the first embodiment, by changing the thickness of resist film 2 and silicon oxide film 3 of the film structure shown in
As shown in
In contrast, as shown in
The result of this calculation is shown in Table 3 below.
The result shown in Table 3 indicates that in a case where the film structure shown in
In the second embodiment, the focal point at the time of exposure can be detected by the same method as in the first embodiment. Also, upper layer film 6 according to the second embodiment is soluble in an alkali solution and therefore can be removed at the time of developing resist film 2. According to the second embodiment, therefore, the desired semiconductor device such as a CMOS device can be fabricated using exposure apparatus 20 through a similar process to that of the first embodiment.
Next, a third embodiment of the invention is explained. According to the third embodiment, the configuration of the focal point detection unit for detecting the focal point at the time of exposure is different from that of exposure apparatus 20 according to the first embodiment. The other component parts are basically similar to those of the first embodiment.
As shown in
According to the third embodiment, exposure apparatus 20 shown in
Also in this third embodiment, similar calculations are made to those described above, and the focal point at the time of exposure can be detected by a basically similar method to that in the first embodiment. Also, the desired semiconductor device such as a CMOS device can be fabricated through similar processes to those of the first embodiment using exposure apparatus 20 according to the third embodiment.
Next, a fourth embodiment of the invention is explained with reference to
By forming an anti-reflection film having a high capability of absorbing the wavelength area of the detection light as described above, the intrusion of the detection light into the lower layers than the anti-reflection film can be suppressed, and the focal point detection error attributable to the variations of various conditions including the thickness and material of the lower layers than the anti-reflection film can be reduced.
The wavelength of the detection light is generally about 450 nm to 850 nm. According to the fourth embodiment, therefore, a material capable of absorbing the light having the wavelength of not less than 450 nm is selected for the anti-reflection film 4 (
In a case where anti-reflection film 4 of an inorganic material is used as described above, the electric characteristics of anti-reflection film 4 may require the removal of anti-reflection film 4 after forming a pattern. In view of this, anti-reflection film 4 may alternatively be formed of an organic material alone. Anti-reflection film 4 may be formed of, for example, a polymer containing a medium such as a pigment having the capability of absorbing the wavelength area of the detection light.
Now, an example of a material of anti-reflection film 4 according to the fourth embodiment is explained specifically. Anti-reflection film 4 can be configured of an acid catalyst crosslinking polymer having the main chain thereof modified, by ester bond, ether bond or amide bond, with a pigment capable of absorbing the light in the wavelength area of 450 nm to 850 nm and a pigment capable of absorbing the light in the exposure wavelength region and a material containing a component for supplying an acid. Specifically, a material usable for anti-reflection film 4 is a mixture of an acid catalyst crosslinking agent and a polymer having a crosslinking reaction point, or a polymer of a material including a crosslinking side chain such as epoxy having the main chain thereof modified, by ester bond, ether bond or amide bond, with a pigment capable of absorbing the light within the long wavelength area of 450 nm to 850 nm and a pigment capable of absorbing the light within the exposure wavelength region (say, 193 nm) and a material containing an acid or a hot acid generator. More specifically, anti-reflection film 4 may be configured of a mixture of a crosslinking agent formed of a polymer of the methoxymethyl amino group and the hydroxyl group having the main chain thereof modified, by ester bond, ether bond or amide bond, with the indigo-group parents capable of absorbing the light within the wavelength area of 450 nm to 850 nm and a compound containing a benzene ring capable of absorbing the light within the exposure wavelength region and a hot acid generator.
The pigment used in this case may have parents in the azo group, quinone group, cyanine group, phthalocyanine group or indigo group.
As shown in
The present inventor has also studied the thickness of the coating of the anti-reflection film, the result of which is explained below with reference to
The thickness of the anti-reflection film formed on each substrate having the film structure described below is changed, and the light having a wavelength of 633 nm is applied to the resist film on the anti-reflection film at the incidence angle of 86°. Under this condition, the relation between the reflectivity of the light in the surface boundary between the resist film and the anti-reflection film and the thickness of the anti-reflection film was studied. The number of aperture (NA) is about 1.327, and the s-polarized light, the p-polarized light or the linearly polarized light of 45 degrees is selected as illumination light.
As understood from
Also in the fourth embodiment, the focal point at the time of exposure can be detected by the same method as in the first embodiment. Also, the desired semiconductor device such as a CMOS device can be fabricated using exposure apparatus 20 according to the fourth embodiment through the same steps as in the first embodiment.
Next, a fifth embodiment of the invention is explained with reference to
As shown in
Also in exposure apparatus 20 using a gas as an exposure medium in the aforementioned case, the focal point can be detected using a similar detection light to each embodiment described above. Also, the desired semiconductor device such as a CMOS device can be fabricated using exposure apparatus 20 according to the fifth embodiment through a similar process to that of the first embodiment.
Embodiments of the invention are explained above, and an appropriate combination of any of the embodiments is presupposed.
Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
Number | Date | Country | Kind |
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2005-285011 | Sep 2005 | JP | national |