JP2008021869A - Plasmon resonation lithography and lithogram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide near-field lithography in which the direction of a mask pattern is not restricted and there is no increase in the number of masks and the quantity of work, and which makes it possible to form a resist pattern narrower than the minimum line width of the mask pattern and carries out new exposure/pattern formation which are not in prior art, and a lithogram. <P>SOLUTION: There is provided near-field optical lithography for carrying out light exposure by irradiating a photoresist with light via a photomask, and carrying out the exposure of the photoresist using near-field light generated near the photomask. The frequency of irradiating light to the photomask is made to be in agreement with the frequency of plasmon resonation generated in the light-shielding film of the photomask. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to plasmon resonance lithography and lithograms.

  Conventionally, for example, Patent Document 1 is known. In Patent Document 1, in order to provide a low-cost near-field light exposure method capable of exposing a fine pattern of 100 nm or less using near-field light that is not limited by the light source wavelength, the near-field light is received by receiving irradiation light. The second resist layer is irradiated with near-field light using an exposure mask that generates a pattern, and the resist layer is developed to form a diffraction grating pattern. Using this as an etching mask, the first resist layer is dry-etched onto the substrate. In the near-field light exposure method for forming a pattern, a complicated pattern 4 is divided into slit patterns 5 and 6 arranged in one direction, and a plurality of exposure masks 2 and 3 are prepared for each divided slit pattern, and optimal exposure is performed. There is described an invention in which a complicated pattern is formed by exposure according to conditions (see FIG. 31).

  Further, in Patent Document 1, near-field light is generated as shown in FIG. 32 (FIG. 8 of Patent Document 1) by near-field optical lithography developed as a method for creating a shape having a size smaller than the wavelength of light. When the exposure mask 104 is brought into close contact with the photosensitive resist material 103 ′ to transfer near-field light having a fine distribution below the wavelength, the polarization direction of the irradiation light L (for example, P-polarized light) is shown in FIG. ) Is parallel to the direction of the slit 110 of the exposure mask 104 (in the direction perpendicular to the paper surface in FIG. 32), and the seepage of the near-field light 107 is localized and normal. However, as shown in FIG. 32B, when the deflection direction indicated by the solid arrow of the irradiation light L is perpendicular to the direction of the slit 110 (and both directions of the optical axis) (the horizontal direction of the paper), With a slit pattern, etc. There is a problem that becomes a different transcription patterns. Therefore, when there are slits whose directions are orthogonal to each other, there is a disadvantage that the transfer pattern of one of the slits is different from the original slit pattern.

  In order to solve this, in the invention described in Patent Document 1, as shown in FIG. 33 (FIG. 2 of Patent Document 1), the mask pattern is divided into two masks and exposed in two steps. First, when the exposure mask 2 is used for exposure, the exposure mask 2 and the second resist layer 7 of the substrate are brought into close contact with each other by evacuation, and then light L such as g or i line is applied to the exposure mask 2 from a mercury lamp light source. Irradiation generates near-field light, and the pattern 5 is transferred to the second resist layer. The polarization direction of the light L at this time is linearly polarized light parallel to the longitudinal direction of the slit pattern of the exposure mask 2. When the exposure of the exposure mask 2 is completed, the exposure mask 2 and the second resist layer 7 are peeled off, and then the exposure mask 3 is adhered to the second resist layer 7. Subsequently, the exposure mask 3 is irradiated with light L such as g-line to generate near-field light, and the pattern 6 is transferred to the second resist layer 7. At this time, the polarization direction of the light L is also linearly polarized light parallel to the longitudinal direction of the slit pattern of the exposure mask 3. In this way, the complex pattern 4 of the exposure mask 1 is transferred to the second resist layer 7 by multiple exposure.

  Patent Document 2 discloses an opening having longitudinal directions in directions orthogonal to each other for the purpose of providing a near-field light mask, an exposure apparatus, and a method that provide exposure with excellent resolution, throughput, and economy. There is also described an invention that provides an exposure method characterized by comprising a step of closely attaching a formed mask to an object to be processed and a step of irradiating the mask with exposure light polarized in directions other than the respective directions. (Exposure device: see FIG. 34).

In Patent Document 3 and Non-Patent Document 1, bleeding occurs from a minute opening when irradiating light polarized in a direction perpendicular to the longitudinal direction of the minute opening and when irradiating light polarized in parallel. It is disclosed that the intensity of the emitted near-field light changes.
Therefore, in exposure using near-field light, if exposure is performed without controlling the polarization of the exposure light, the near-field light that oozes out from the minute aperture depending on the polarization direction of the exposure light with respect to the longitudinal direction of the minute aperture formed in the mask. The intensity of the film changes, and the exposure pattern becomes uneven.

In addition, in order to solve these problems, Patent Document 2 includes a step of closely attaching a mask having an opening having a longitudinal direction in a direction orthogonal to each other to the object to be processed, and polarization in a direction other than the above directions. Irradiating the mask with exposure light. According to this exposure method, the intensity of the near-field light that oozes out from the opening can be made constant. The irradiation step further includes a step of detecting a longitudinal direction of the opening of the mask and a step of generating the exposure light based on the detection result. The irradiating step irradiates the mask with exposure light polarized in a direction of an angle of about 45 ° with respect to the longitudinal direction of the opening. The openings are formed only in directions orthogonal to each other, and the mask 400 used in the present invention includes a mixture of the minute openings 432 shown in FIGS. Therefore, the same exposure light is incident on the minute aperture 432 shown in FIGS. 35 and 36, and both the x-direction component and the y-direction component are polarized with the same intensity. In the invention described in Patent Document 2, as shown in FIG. 37, the longitudinal direction of the minute opening 432 is oriented only in two directions, the x direction and the y direction. Therefore, the intensity of the near-field light that oozes out from the minute opening 432 is constant regardless of whether the longitudinal direction of the minute opening 432 is in the x direction or the y direction. That is, the mask 400 used in the invention of Patent Document 2 is polarized on the mask 400 by setting the polarization direction B of the exposure light with respect to the longitudinal direction (x direction and y direction) of the minute opening 432 to an angle of about 45 °. The intensity of the near-field light that oozes out from the minute aperture 432 is made constant without creating a child.
JP 2003-234274 A JP 2004-111500 A JP 2000-112116 A Sub-diffraction-limited patterning using evanescent near-field optical lithography [MMAlkaisi et al Appl. Phys. Lett. Vol.75, Num.22 (1999)]

However, in Patent Document 1 described above, the mask is divided into two masks according to the direction of the slit pattern in order to overcome the disadvantage that the exposure width becomes thick depending on the direction of the slit pattern, which is a disadvantage of near-field photolithography. Perform alignment and exposure twice. In this case, since the work from taking out the mask from the storage location and returning it to the original storage location after exposure must be performed twice, the operation time is doubled. In addition, since two masks must be prepared, the productivity is lowered, which causes high costs.
Further, Patent Document 2 overcomes the drawbacks of Patent Document 1, but has a disadvantage that the longitudinal direction of the slit pattern is limited only to directions orthogonal to each other.

  In view of such a problem, an object of the present invention is to provide a plasmon resonance lithography and a lithogram in which the frequency of light irradiated onto a photomask matches the frequency of plasmon resonance in the light shielding film of the photomask.

  In order to achieve the above object, the invention according to claim 1 is a proximity method in which the photoresist is exposed to light through a photomask and exposed to light, and the photoresist is exposed by near-field light generated in the vicinity of the photomask. It is a field light lithography, characterized in that it is a plasmon resonance lithography in which the frequency of light irradiated to the photomask is matched with the frequency of plasmon resonance generated in the light shielding film of the photomask.

  According to a second aspect of the present invention, in the plasmon resonance lithography according to the first aspect, the irradiation light is deflected light, and the deflected light is linearly deflected light.

  According to a third aspect of the present invention, in the plasmon resonance lithography according to the second aspect, the linearly polarized light is further exposed a plurality of times.

  According to a fourth aspect of the present invention, in the plasmon resonance lithography according to the first aspect, circularly or elliptically deflected light is used as the irradiation light.

  The invention described in claim 5 is characterized in that, in the plasmon resonance lithography according to claim 1, random deflection light is used as the irradiation light.

  The invention according to claim 6 is the plasmon resonance lithography according to any one of claims 1 to 5, wherein the light shielding film pattern of the photomask is an island pattern, a hole pattern, a circular pattern, a square pattern, It is at least one pattern of a triangular pattern or a strip pattern.

  The invention described in claim 7 is a lithogram created by the plasmon resonance lithography described in any one of claims 1 to 6.

  Thus, according to the plasmon resonance lithography and lithogram of the present invention, it is possible to provide near-field optical lithography that does not limit the direction of the mask pattern and does not increase the number of masks and the amount of work.

The present embodiment overcomes the drawbacks of Patent Documents 1 and 2 described above, provides near-field lithography and lithogram with no restrictions on the mask pattern direction and no increase in the number of masks and the amount of work, The object is to enable formation of a resist pattern narrower than the minimum line width.
Another object of the present embodiment is to perform novel exposure / pattern formation that is not found in the prior art.

The plasmon resonance lithography and lithogram of this embodiment will be described in detail below with reference to the drawings.
The plasmon resonance lithography of the present embodiment is near-field optical lithography in which a photoresist is irradiated with light through a photomask for exposure, and the photoresist is exposed to near-field light generated in the vicinity of the photomask. The frequency of the light irradiated to the photomask is made to coincide with the frequency of plasmon resonance generated in the light shielding film of the photomask.

[First Embodiment]
First, a description will be given with reference to FIGS. FIG. 1 shows a basic process of plasmon resonance lithography according to this embodiment. First, in the process shown in FIG. 1 (1), a thin film to be processed is deposited on a substrate such as glass or silicon. The deposited thin film (non-patterning layer) can be formed using a metal, a dielectric, a semiconductor, or the like. Although the method for forming these thin films is not particularly limited, it can be formed by methods such as PVD, CVD, and vapor deposition. On the formed thin film, a lower layer resist having a thickness equal to or greater than the thickness of the thin film is deposited. Although this deposition method is not limited, for example, a coating method such as spin coating or roll coating can be employed. As the lower layer resist, one having no photosensitivity can be selected. Further, a photosensitive upper layer resist (upper layer photoresist) is laminated on the lower layer resist.

  Next, after a photomask (metal light shielding film) on which a pattern is formed is placed on the upper resist, the above-described metal light shielding film is strongly adhered by a vacuum contact method or the like (see FIG. 1 (2)).

  Thereafter, light having a wavelength λ that the upper resist is exposed is irradiated from the photomask side through a glass (or quartz) substrate (see the exposure process in FIG. 1 (3)). The wavelength λ of the irradiation light is a wavelength at which plasmon resonance occurs in the metal light-shielding film that is a photomask by irradiating light (in fact, the dielectric constant of the medium). It is necessary to select a frequency that can be determined regardless of the frequency. The plasmon resonance frequency is determined by the optical characteristics and shape of the light shielding film material of the photomask and the optical characteristics of the upper layer resist. After the exposure process of FIG. 1 (3), the upper layer photoresist is developed by the development process of FIG. 1 (4).

  Here, the case where the light of the plasmon resonance frequency is irradiated is compared with the case where it is not, with reference to FIGS.

  FIG. 2 is a diagram showing a circular stripe pattern of a photomask having an interval shown in FIG. 2 using, as an example, irradiation light having a plasmon resonance frequency and using the irradiation light as shown in FIG. . FIG. 3 is a diagram showing the electric field intensity distribution due to the irradiation light in the upper layer resist when the photomask having the pattern of FIG. 2 is irradiated with light having a wavelength λ of 500 nm in vacuum. On the other hand, FIG. 5 shows the electric field distribution in the photoresist when irradiated with light having a linearly polarized light and a wavelength of 300 nm shown in FIG. 4, which is not the plasmon resonance frequency, using a photomask having a pattern at intervals shown in FIG. All are the results of simulation calculation by FDTD (Finite Difference Time Domain method).

  Comparing FIG. 3 and FIG. 5, since plasmon resonance occurs in the light-shielding film metal of the photomask in FIG. 3, the electric field is at the edge of the linear polarization direction of the metal dot (if the linear polarization direction is x, this is It is concentrated (along the substantially perpendicular y direction) (the portion where the light intensity is strong in FIG. 3). For this reason, there is almost no electric field between the dots, and the intensity of the electric field itself is nearly 100 times stronger than in the case of non-plasmon resonance. On the other hand, in FIG. 5, since an electric field also exists in the portion between the dots, the exposure area similar to that in FIG. 32 showing the prior art is expanded, and it becomes impossible to produce a fine pattern. That is, when FIG. 3 and FIG. 5 are compared, a portion having a high light intensity appears at both edges in the y direction of each circular stripe as shown in FIG. 3, and the center of each circular stripe has a low light intensity. On the other hand, since the light intensity is extremely low between the circular striped patterns, it can be seen that the concentration of the light intensity is extremely efficient. On the other hand, in the region far from the plasmon resonance frequency, only a part of the circular stripes appear in both edges in the y direction as shown in FIG. 5, and there is some light intensity between the circular stripe patterns. It can be seen that the light intensity is not concentrated so much as in a certain state.

  As described above, in plasmon resonance lithography, the electric field concentrates on the pattern edge in the direction of linear polarization, so that exposure with a smaller size than the photomask pattern and twice the period of the photomask pattern is possible. FIG. 1 (3) shows a state in which exposure by such plasmon resonance lithography is performed.

  Further, as shown in (4) of FIG. 1, after the exposure is completed, the upper layer resist is developed to form a resist pattern. Thereafter, as shown in FIG. 1 (5), the lower layer resist is etched with a high aspect ratio by oxygen plasma by RIE (reactive ion etching) or the like using this pattern as an etching mask. Thereafter, as shown in FIG. 1 (6), the thin film (patterned layer) is etched by RIE or the like (in the case where the thin film is a metal film such as Al or Cu, an acidic gas (for example, chlorine-based gas)). In addition, Si or silicon oxide is treated with a fluorine-based gas such as SF6). Furthermore, as shown in FIG. 1 (7), ashing with oxygen plasma, organic solvent, stripping solution, etc. Remove the resist. And the state of the thin film formed in the pattern shape created by such a process of (1)-(7) of FIG. 1 is shown in (8) of FIG.

[Second Embodiment]
Next, a second embodiment relating to plasmon resonance lithography of the present embodiment will be described with reference to FIGS. In the second embodiment, the island pattern is a quadrangle.

  When plasmon resonance is generated in the same manner as in the first embodiment with linearly polarized light in the direction of FIG. 6 (lateral direction in the drawing), two in the y direction orthogonal to x, which are two opposite sides of the quadrangle, with respect to the linearly polarized light direction x. The electric field concentrates on the side (see FIG. 7). The upper layer photoresist is exposed to a place where the electric field is concentrated as shown in FIG. 7, and the exposed portion of the thin film is removed through the same process as described above. Other effects and processes are the same as those in the first embodiment.

[Third Embodiment]
Next, FIGS. 8 and 9 show a third embodiment relating to the plasmon resonance lithography of the present embodiment. In the present embodiment, an example in which the island pattern is a triangle is shown as the pattern shape. When plasmon resonance is generated in the linear polarization direction x (direction orthogonal to one side (y direction) of the triangle) shown in FIG. 8 as in the first embodiment, the electric field is concentrated on one side of the y direction (FIG. 9). reference). Therefore, as shown in FIG. 9, the upper layer photoresist where the electric field is concentrated is exposed, and the exposed portion of the thin film is removed through the process described in the first embodiment. Since other effects and processes are the same as those in the first embodiment, description thereof will be omitted.

[Fourth Embodiment]
In the first embodiment, the photomask pattern is a circular island pattern, but in the present embodiment, a circular hole pattern is used. As in the first embodiment, the frequency of irradiation so that plasmon resonance occurs in the light shielding film material of the photomask, the optical characteristics and shape of the light shielding film material of the photomask, and the optical characteristics of the upper layer resist are determined. . FIGS. 10-14 is the figure which compared the case where it is not so with the case where the light of a plasmon resonance frequency is irradiated.

  FIG. 10 shows a case where irradiation light having a plasmon resonance frequency is used, linearly polarized light is used as the irradiation light (in the horizontal direction of the paper: the x direction as in the first embodiment), and the photomask pattern is a circular hole pattern. It is a figure which shows an example of a pattern space | interval. FIG. 11 is a diagram showing an electric field intensity distribution by irradiation light in the upper resist when the photomask having the pattern shown in FIG. 10 is irradiated with light having a wavelength of 500 nm in vacuum. On the other hand, FIG. 14 shows the electric field distribution in the photoresist when the photomask having the pattern interval shown in FIG. 13 is irradiated with light having a wavelength of 300 nm which is not the plasmon resonance frequency. All are the results of simulation calculation by FDTD (Finite Difference Time Domain method).

  Comparing FIG. 11 with FIG. 14, since plasmon resonance is generated in the light shielding film metal of the photomask in FIG. 11, electrons are concentrated on the edge side of the hole in the metal light shielding film in the linear polarization direction. . In addition, there is almost no electric field in the light-shielding film portion between the holes, and the intensity of the electric field itself is nearly 100 times higher than in the case of non-plasmon resonance. On the other hand, in FIG. 14, there is an electric field in the portion between the holes. For this reason, as in FIG. 32 of the prior art, the exposure area is widened, making it impossible to produce a fine pattern. As described above, in plasmon resonance lithography, the electric field concentrates on both edges of the linearly polarized light direction (y direction orthogonal to the x direction: the vertical direction on the paper surface), so that the size of the photomask pattern is smaller than that of the photomask pattern. Exposure with a double cycle is possible. FIG. 12 shows a state in which such exposure is performed.

[Fifth Embodiment]
A fifth embodiment relating to plasmon resonance lithography of the present embodiment will be described with reference to FIGS. 15 and 16. In the fifth embodiment, an example in which the hole shape pattern is a quadrangle is shown. When plasmon resonance is generated in the direction of the linearly polarized light (x direction) shown in FIG. 15 as in the first embodiment, two opposite sides of the quadrangle (2 in the y direction orthogonal to the x direction) as shown in FIG. The electric field concentrates on the side. Since other effects and processes are the same as those in the fourth embodiment, description thereof will be omitted.

[Sixth Embodiment]
A sixth embodiment relating to plasmon resonance lithography of the present embodiment will be described with reference to FIGS. 17 and 18. In the sixth embodiment, the hole shape pattern is a triangle. When plasmon resonance is generated in the same way as in the first embodiment with linearly polarized light in the direction of FIG. 17 (direction orthogonal to one side of the triangle), as shown in FIG. 18, the electric field concentrates on the orthogonal side. The effects and processing processes are the same as in the first embodiment.

[Seventh Embodiment]
A seventh embodiment relating to plasmon resonance lithography of the present embodiment will be described with reference to FIG. In the first embodiment or the fourth embodiment, the light of the polarization A shown in FIG. 19A is irradiated (exposure), and then the polarization direction is changed to the polarization B to be exposed, and the polarization direction is changed to the polarization C. Change the exposure. As can be seen from FIGS. 3 and 11, since the electric field is small (in other words, the amount of light is small) except for the edge portion in the polarization direction where the electric field is concentrated by plasmon resonance, the multiple exposure as described above is performed in this embodiment. Even if the resist is used, the resist is exposed only at the edge portion described above. Therefore, if one mask is used, it is possible to expose three polarization directions A to C × 2 = 6 (hexagon shown in FIG. 19A). FIG. 19B is an example using polarized light A and B (two polarization directions × 2 = 4 locations), and FIG. 19C is an example of three locations in the three polarization directions of polarization directions A to C ( See FIG. 29 (c)).
As a result, as shown in FIG. 19, patterns in three directions corresponding to the exposures can be engraved on the thin film.

  In the example shown in the drawing of Patent Document 1, when exposure is performed using polarized light in two or more directions, a photomask is processed at each exposure when changing the polarization direction for exposure. It was necessary to replace the mask with another mask and perform re-exposure. Therefore, since the second exposure must be performed before developing after the first exposure, the alignment mark is not patterned only by the first exposure (that is, since it does not develop), it functions as an alignment mark. Absent. Therefore, the alignment at the second exposure cannot be performed with the alignment mark as a target, and the alignment / exposure with high accuracy cannot be performed.

  On the other hand, in the present embodiment, since it is not necessary to separate the photomask from the substrate to be processed (in other words, the upper layer photoresist provided on the substrate), there is no problem as described above, and multiple exposure is performed using the photomask. Can be done without changing. This makes it possible to process a more complicated pattern.

  In the present embodiment, an embodiment of a circular dot or hole-shaped pattern is shown, but this may be a square or triangular dot or hole-shaped pattern. In the case of a quadrangle such as a rectangle (rectangular or parallelogram), there are two types of linear polarization directions (that is, two parallel sides) corresponding to the two sets of edges, so that each polarization is performed twice. When development and ashing are performed after exposure (the steps shown in FIGS. 1 (4) to (7) are performed), a pattern as shown in FIG. 19 (b) can be engraved on the thin film. Further, in the case of triangular dots, the pattern shown in FIG. 19C can be engraved on the thin film by performing exposure with linearly polarized light orthogonal to each side of the triangle (FIGS. 1 (4) to (7)). (Refer to the process shown in the above)

[Eighth Embodiment]
With reference to FIG. 20, an eighth embodiment relating to plasmon resonance lithography of the present embodiment will be described. In the first embodiment or the fourth embodiment, when exposure is performed with circularly polarized light shown in FIG. 20, in the case of circularly polarized light, the electric field concentration portion shown in FIGS. 3 and 11 rotates at the frequency of the irradiation light. Will do. As can be seen from FIGS. 3 and 11, since the electric field is small (that is, the amount of light is small) except for the edge portion in the polarization direction where the electric field is concentrated by plasmon resonance, the circular pattern shown in FIG. (Steps shown in FIGS. 1 (4) to (7) are performed).

In this embodiment, an example of a circular dot or hole-shaped pattern is shown, but a square or triangular dot or hole-shaped pattern may be used. These can engrave a pattern as shown in FIGS. 19B to 19C on a thin film.
When exposed with elliptically polarized light, the amount of exposure in the major axis direction of the elliptically polarized light is greater than the amount of light in the minor axis direction, so the major axis width of the donut-shaped pattern is wider than the minor axis width. Become.
Even when exposure is performed with random polarized light (polarized light in which the direction of unidirectional polarized light is changed randomly), a pattern similar to the case of exposure with circularly polarized light can be formed as long as the variation in polarization is uniform. .

[Ninth embodiment]
A ninth embodiment relating to plasmon resonance lithography of the present embodiment will be described with reference to FIGS.
In this embodiment, a photomask in which strip-like rectangular island patterns are formed is used. In the photomask, a light shielding film may be formed on the photomask substrate as shown in FIG. 21B, or the surface of the light shielding film and the substrate surface are flush with each other as shown in FIG. You may form in.

  When plasmon resonance is generated in the same way as in the first embodiment with linearly polarized light in the direction shown in FIG. 22 (lateral direction in the drawing), the electric field concentrates on the edge portion of the strip-shaped rectangular pattern as shown in FIG. The upper layer photoresist where the electric field is concentrated is exposed to light, and the exposed portion of the thin film is removed through the process shown in FIG. Then, as shown in FIG. 23, a slit-like pattern can be engraved on the thin film. In the present embodiment, since the exposure area does not widen as shown in FIG. 32 showing the prior art, it becomes easy to produce a fine pattern. In addition, since the electric field concentrates on the pattern edge in the linear polarization direction, it is possible to form a slit pattern that is smaller in size than the photomask pattern and has a period twice that of the photomask pattern.

  FIG. 24 shows another example, which uses a photomask in which strip-like rectangular hole patterns are formed. Also in this example, since the electric field concentrates on the edge portion of the strip rectangular hole pattern, the same effect as the example shown in FIGS. 21 to 23 can be obtained. The effects and processing processes are the same as those in the first embodiment. In the present embodiment, a photomask formed so that the light shielding film surface and the substrate surface are flush with each other may be used.

[Tenth embodiment]
A tenth embodiment relating to plasmon resonance lithography of the present invention will be described with reference to FIGS. FIG. 25 is a diagram showing an example of a photomask in which a rectangular strip-shaped hole pattern is formed in two directions orthogonal to each other and is L-shaped. Using such a photomask, the photomask is brought into intimate contact with the photoresist on the substrate to be processed as shown in FIG. 1, and first, as shown in FIG. When irradiated, for example, as shown in FIG. 26A, the electric field concentrates on the side perpendicular to the polarization A direction of the L-shaped pattern. Further, as shown in FIG. 26 (b), when linearly polarized light (vertical direction in the drawing) of polarized light B orthogonal to polarized light A is applied, the electric field concentrates on the side perpendicular to the polarized light B direction of the L-shaped pattern. . Accordingly, after this, the process shown in FIG. 1 (4) and subsequent steps can be performed to form a pattern as shown in FIG. In this embodiment, unlike Patent Document 1, since it is not necessary to separate (separate) the photomask from the substrate to be processed, multiple exposure can be performed without causing the above problems. This makes it possible to process a more complicated pattern.

  Another example will be described with reference to FIGS. In this example, as shown in FIG. 28, a rectangular rectangular slit pattern is arranged at a right angle, and a third slit is arranged between each of the rectangular strips at an angle of 45 degrees on both sides of the strip. . Using this photomask, exposure is performed three times in total using linearly polarized light (polarized light A, polarized light B, and polarized light C) perpendicular to the longitudinal direction of these slits. Thereby, the thin film pattern shown in FIG. 29 is formed by the principle and processing method described above.

[Eleventh embodiment]
With reference to FIGS. 25 and 30, an eleventh embodiment relating to plasmon resonance lithography of the present embodiment will be described. When exposure is performed using circularly polarized light using the photomask of FIG. 25, the electric field concentrates on the edge portion in the longitudinal direction of the slit extending in two directions as shown in FIG. Thereby, the same pattern as FIG. 27 is formed in the thin film. When exposure is performed with elliptically polarized light, the exposure amount in the major axis direction of the elliptically polarized light is larger than the exposure amount in the minor axis direction, so the electric field generated in the longitudinal direction of the slit perpendicular to the major axis direction is the minor axis. It becomes stronger than the electric field generated in the direction. Therefore, the pattern of the edge portion of the slit perpendicular to the major axis direction is wider than the pattern of the edge portion of the slit perpendicular to the minor axis direction.
When exposure is performed with randomly polarized light, a pattern similar to that when exposed with circularly polarized light can be formed as long as the variation in polarization is uniform.

  As described above, with the plasmon resonance lithography of the present embodiment, the frequency of irradiation light to the photomask is set to a frequency at which plasmon resonance is generated in the light shielding film of the photomask, thus overcoming the drawbacks of Patent Documents 1 and 2. Providing near-field lithography with no restrictions on the mask pattern direction and no increase in the number of masks and the amount of work, and further enabling the formation of a resist pattern narrower than the minimum line width of the mask pattern it can.

  In addition, the plasmon resonance lithography of this embodiment further provides near-field lithography in which the direction of the mask pattern is not limited and the number of masks and the amount of work are not increased, and the resist is narrower than the minimum line width of the mask pattern. A pattern can be formed.

  Further, in the plasmon resonance lithography of the present embodiment, the light shielding film pattern of the photomask is at least one pattern of an island pattern, a hole pattern, a circular pattern, a square pattern, a triangular pattern, and a strip pattern. In addition to the effects peculiar to the embodiment, the flexibility of pattern selection is wide, and various shapes of thin films can be efficiently produced at low cost.

  The lithography produced by lithography of this embodiment can be used as various devices, various recording media, display media, and various information media, and can be used in a wide range of fields such as the printing field, electronic field, and element field. The lithography of the present embodiment is a technology with a wide range of applications.

It is a figure which shows the basic process of the plasmon resonance lithography concerning this embodiment. It is a figure which shows the circular striped pattern of the photomask for irradiating the linearly polarized light of a paper surface horizontal direction. FIG. 3 is a drawing-substituting photograph showing an electric field intensity distribution by irradiation light in an upper layer resist when a photomask having the pattern of FIG. 2 is irradiated with light having a wavelength λ of 500 nm in vacuum. It is a figure which shows the circular island pattern of the photomask for irradiating the linearly polarized light of a paper surface horizontal direction. FIG. 5 is a drawing-substituting photograph showing the electric field intensity distribution due to the irradiation light in the upper layer resist when the photomask having the pattern shown in FIG. 4 is irradiated with light having a wavelength λ of 500 nm in vacuum. It is a figure which shows the rectangular island pattern of the photomask for irradiating the linearly polarized light of the paper surface horizontal direction whose irradiation light wavelength is 300 nm. FIG. 6 is a substitute for a drawing showing an electric field intensity distribution in which an electric field is concentrated on two sides in the y direction orthogonal to x, which are two opposite sides of a quadrangle when the photomask having the pattern shown in FIG. 6 is exposed to light in the linear polarization direction x. It is a photograph. It is a figure which shows the triangular island pattern of the photomask for irradiating the linearly polarized light of a paper surface horizontal direction. FIG. 8 is a substitute for a drawing showing an electric field intensity distribution in which an electric field is concentrated on two sides in the y direction orthogonal to x, which are two opposite sides of a quadrangle when the photomask having the pattern shown in FIG. 8 is exposed to light in the linear polarization direction x. It is a photograph. It is a figure which shows the circular hole-shaped pattern of the photomask for irradiating with linearly polarized light as irradiation light. FIG. 11 is a drawing-substituting photograph showing an electric field intensity distribution by irradiation light in an upper layer resist when a photomask having a pattern shown in FIG. 10 is irradiated with light having a wavelength of 500 nm in vacuum. It is the figure which showed electric field strength distribution at the time of irradiating with the irradiation light in an upper layer resist, when the photomask of the pattern shown in FIG. 10 is irradiated with the light whose wavelength is 500 nm in a vacuum. It is a figure which shows the circular hole-shaped pattern of the photomask for irradiating a linearly polarized light as irradiation light (non-plasmon resonance). FIG. 14 is a drawing-substituting photograph showing the electric field distribution in the photoresist when light having a wavelength of 300 nm that is not the plasmon resonance frequency is irradiated through the photomask having the pattern shown in FIG. It is a figure which shows the circular hole-shaped pattern of the photomask for irradiating linearly polarized light as plasmon resonance irradiation light. FIG. 16 is a drawing-substituting photograph showing an electric field distribution in a photoresist when light having a plasmon resonance frequency is irradiated through a photomask having a pattern shown in FIG. 15. It is a figure which shows the circular hole-shaped pattern of the photomask for irradiating with linearly polarized light as irradiation light. FIG. 18 is a drawing-substituting photograph showing an electric field distribution in a photoresist when light having a plasmon resonance frequency is irradiated through a photomask having a pattern shown in FIG. 17. It is a figure explaining 7th Embodiment of the plasmon resonance lithography of this embodiment, (a) irradiates the light of the polarization A (exposure), changes the polarization direction to the polarization B after that, and also exposes, and also polarization It is a figure which shows the example which forms the thin film patterned by exposing and changing the direction to the polarization C, (b) is an example formed using 2 polarized light A and B, (c) is 3 polarized light. It is the example formed using direction AC. It is a figure for description of 8th Embodiment of plasmon resonance lithography concerning this embodiment, and it replaces with circularly polarized light in this embodiment, and exposes the linearly polarized light used in 1st Embodiment or 4th Embodiment. It is the figure which showed forming the pattern of a thin film. It is an example figure of the photomask used for 9th Embodiment of the plasmon resonance lithography of this embodiment, (a) is a photomask in which the strip-shaped rectangular island pattern used by this embodiment is formed ( (B) shows an example in which the photomask is formed with a light shielding film on the photomask substrate, and (c) shows an example in which the light shielding film surface and the substrate surface are formed on the same surface. Indicates. FIG. 22 is a drawing-substituting photograph showing an electric field distribution in which an electric field concentrates on an edge portion of a strip-like rectangular pattern when plasmon resonance is caused by linearly polarized light (lateral direction in the drawing) using the photomask shown in FIG. 21. It is a figure which shows the example of the thin film in which the slit-shaped pattern formed by reducing the electric field strength shown in FIG. 22 by plasmon resonance using the photomask shown in FIG. It is a figure which shows the other example of the photomask shown in FIG. It is an example figure of the photomask used for 10th Embodiment of the plasmon resonance lithography of this embodiment, and the pattern of a photomask becomes L-shape with which the rectangular rectangular hole-shaped pattern was formed in two directions orthogonal to each other It is a figure which shows the example of the photomask which is. FIG. 26 is a drawing-substituting photograph showing an electric field distribution when plasmon resonance exposure is performed using the L-shaped photomask shown in FIG. 25, and (a) is a case where linearly polarized light of polarized light A (horizontal direction on the paper surface) is irradiated. It is an example which shows that an electric field concentrates on the edge | side orthogonal to the polarization A direction of L-shaped pattern of (b), and (b) is the case where the linearly polarized light (vertical direction of a paper surface) of the polarization B orthogonal to the polarization A is irradiated This is an example where the electric field concentrates on the side perpendicular to the polarization B direction of the L-shaped pattern. FIG. 28 is a diagram showing an example of a thin film on which a slit-like pattern formed by reducing the electric field strength shown in FIG. 27 by plasmon resonance using the photomask shown in FIG. 26 is formed. It is a figure which shows the other example of the photomask used for 10th Embodiment of the plasmon resonance lithography of this embodiment, and the pattern of a photomask is arrange | positioned so that a rectangular rectangular slit pattern may become a right angle, Furthermore, It is a figure which shows the example of the photomask by which the 3rd slit is arrange | positioned between each rectangular strip with a 45 degree angle to both strips. It is a figure which shows the example of the thin film by which the pattern was formed by the plasmon resonance using the photomask shown in FIG. FIG. 26 is a drawing-substituting photograph for explaining an eleventh embodiment of plasmon resonance lithography of the present embodiment, and an electric field when plasmon resonance is exposed using circularly polarized light using an L-shaped photomask shown in FIG. 25. It is a drawing substitute photograph which shows distribution. It is a figure regarding invention of patent document 1 which is a prior art, Complicated pattern 4 is divided | segmented into each slit pattern 5 and 6 arranged in one direction, and there are several exposure masks 2 and 3 for every divided slit pattern. It is a figure explaining the pattern formation method which prepares and exposes on optimal exposure conditions and forms a complicated pattern. FIG. 5 is a diagram related to the invention described in Patent Document 1, which is a conventional technique, in which an exposure mask 104 that generates near-field light is brought into close contact with a photosensitive resist material 103 ′ to transfer near-field light having a fine distribution of a wavelength or less. (A) shows a case parallel to the direction of the slit 110 of the exposure mask 104, and (b) shows the deflection direction indicated by the solid line arrow of the irradiation light L with respect to the direction of the slit 110. FIG. It is a figure regarding the invention of patent document 2 which is a prior art, and is a figure which shows the place which divides | segments a mask pattern into two masks and divides and exposes twice. It is a figure regarding invention of patent document 2 which is a prior art, and is a figure regarding exposure apparatus. It is the figure explaining the micro opening 432 (vertical direction) of the mask regarding the invention of patent document 2 which is a prior art. It is the figure explaining the micro opening 432 (horizontal direction) of the mask regarding the invention of patent document 2 which is a prior art. It is explanatory drawing of the opening part of the mask regarding the invention of patent document 2 which is a prior art, and is a figure which shows the mask shape in which the minute opening 432 is mixed.

Explanation of symbols

1 Thin film (patterned layer)
2 Lower layer resist 3 Upper layer photoresist 4 Photomask 10 Substrate

Claims (7)

Near-field optical lithography in which a photoresist is irradiated with light through a photomask and exposed to light to expose the photoresist with near-field light generated near the photomask;
Plasmon resonance lithography, characterized in that a frequency of light applied to the photomask is matched with a frequency of plasmon resonance generated in a light shielding film of the photomask.   2. The plasmon resonance lithography according to claim 1, wherein the irradiation light is deflected light, and the deflected light is linearly deflected light.   3. The plasmon resonance lithography according to claim 2, wherein the linearly polarized light is exposed a plurality of times.   2. The plasmon resonance lithography according to claim 1, wherein circular irradiation light or elliptical polarization light is used as the irradiation light.   2. The plasmon resonance lithography according to claim 1, wherein random irradiation light is used as the irradiation light.   6. The light-shielding film pattern of the photomask is at least one pattern of an island pattern, a hole pattern, a circular pattern, a square pattern, a triangular pattern, or a strip pattern. The plasmon resonance lithography according to item.   A lithogram produced by plasmon resonance lithography according to any one of claims 1 to 6.

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