JP2003007599A - Method and device for forming pattern with proximity field light - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for forming a pattern with proximity field light arranged as a proximity field light lithography developed from a proximity field microscope employing a probe in which highly accurate control can be ensured while reducing the size. SOLUTION: The system for forming a pattern with proximity field light by irradiating a plane coated with photosensitive resist 8 with proximity field light from an exposure light source comprises a probe (cantilever) 9 having a extremely thin forward end generating proximity field light disposed on the surface of the photosensitive resist 8, and a unit for irradiating blue semiconductor laser light, while converging, from the rear side of the photosensitive resist 8 disposed at the forward end of the probe (cantilever) 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-field pattern forming method and apparatus for performing ultra-fine processing using near-field light.

[0002]

2. Description of the Related Art Photolithography technology is an essential elemental technology in semiconductor processes.

In lithography using light, the diffraction limit of light is said to be the limit of resolution and accuracy. Therefore, in order to miniaturize the semiconductor, it is adopted to shorten the wavelength of light used for exposure, and the wavelength is g-line (436n).
m), i-line (365 nm), and excimer lasers (248 nm, 193 nm) have been shortened, but the diffraction limit is said to be about half of the wavelength, and even if excimers are used, the resolution is 100 nm at most. It only happened.

Lithography using an electron beam or X-ray other than light requires a large amount of equipment, has problems in throughput, development of a mask and a resist material, and the like.

On the other hand, in recent years, the development of a near-field microscope having micropores or using a fine probe (probe), particularly a near-field scanning microscope (NSOM), has been remarkable,
A molecular scale image became visible. There are four types of probes used here. That is, (a) micro aperture, (b) micro probe, (c) micro optical waveguide, (d)
This is a fine optical waveguide coated with metal, and fine processing using near-field light using these is being studied.

The following are cited as prior art references.

(1) Kawada Inoue Applied Physics Vol. 67
No. 12 pp1376-1382 (1998) (2) Kawada, Measurement and Control, Volume 38, No. 12, pp7
37-741 (1999) (3) Kawada Toray Research Center THE TRC
NEWS No. 73 (2000) (4) JP-A-4-291310 "Metal-coated fiber type" (5) JP-A-7-106229 "Fiber type" (6) JP-A-8-179493 "Micro opening using a mask" (7) Japanese Patent Application Laid-Open No. 10-326742 "Fiber type" (8) Japanese Patent Application Laid-Open No. 11-145051 "Mask" (9) Japanese Patent Application Laid-Open No. 11-233427 "Micro opening" (10) Japanese Patent Application Laid-Open No. 2000-321756 Further, a proposal regarding a near-field microscope using a metal probe has already been proposed by the inventor of the present application in the literature: Optics Com.
communications 183, pp 333-336
(2000), Optics Letters, 19,
pp159-161 (1994) and JP 2000-8.
It is shown as No. 1383.

[0008]

However, in the above-mentioned fiber type, since the hole portion at the tip needs to be thinned for fine processing, the light utilization efficiency is significantly reduced at a half wavelength or less of the incident light. However, there is a problem in that only extremely weak light is obtained, and it takes a long time for processing.
This also applies to the method using the mask. Therefore, only the method using a metal probe is possible.

Further, in the near-field microscope using the above-mentioned metal probe, there is a demand for a compact one having a high resolution and capable of accurately controlling the size and position.

In view of the above circumstances, the present invention provides a method for forming a pattern by near-field light, which is configured as near-field light lithography which is a development of a near-field microscope using a probe, which is compact and can be controlled with high accuracy. The purpose is to provide the device.

[0011]

In order to achieve the above object, the present invention uses [1] near-field light for irradiating a surface coated with a photosensitive resist with near-field light as an exposure light source to form a pattern. In the pattern forming method, the probe coated with a photosensitive resist is irradiated with near-field light as an exposure light source to form a pattern. Is disposed on the surface of the photo-sensitive resist, and the near-field light whose electric field is enhanced by irradiating and converging a laser beam on the tip of the probe to the photo-sensitive resist is used. .

[2] In the pattern forming method using near-field light according to the above [1], the laser light is blue semiconductor laser light, and the photo-sensitive resist is irradiated and converged from the back surface or the side surface. .

[3] In the pattern forming method using near-field light according to the above [1], a probe having an extremely thin tip for generating the near-field light is arranged on the surface of the photosensitive resist, and the probe is A near-field light whose electric field is enhanced by irradiating and converging a blue semiconductor laser light on the tip of the needle from the back surface side of the photosensitive resist is used.

[4] In the pattern forming method using near-field light described in [1] above, the probe has a tip curvature of 50.
It is characterized in that it is a cantilever of nm or less.

[5] In the pattern forming method using near-field light as described in [3] above, the probe is made of a metal, a dielectric or a semiconductor.

[6] In the pattern forming method using near-field light according to the above [4], a silicon cantilever is used,
The photo-sensitive resist is a g-ray resist having a thickness of 100.
nm coating and drawing with a blue semiconductor laser beam of 405 nm.

[7] In the pattern forming method using near-field light according to the above [6], a plurality of lines having a width of 100 nm and a depth of 10 nm are drawn with a low power of 5 to 10 mJ / cm ² at a drawing speed of about 100 μm per second. It is characterized by

[8] In a pattern forming apparatus using near-field light for irradiating a surface coated with a photo-sensitive resist with near-field light as an exposure light source to form a pattern, the pattern forming device is arranged on the surface of the photo-sensitive resist and The probe is characterized by comprising a probe having an extremely thin tip for generating field light, and a laser beam irradiation device for irradiating and converging the photo-sensitive resist on the tip of the probe.

[0019]

[9] In the pattern forming apparatus using near-field light according to the above [8], the probe has a tip curvature of 50.
It is characterized in that it is a cantilever of nm or less.

[10] Above

In the pattern forming apparatus using near-field light described in [9], the probe is made of a metal, a dielectric, or a semiconductor.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

FIG. 1 is a schematic view of a main part of a near-field lithography apparatus showing an embodiment of the present invention, and FIG. 2 is an overall schematic view of a near-field lithography apparatus showing an embodiment of the present invention.

In these figures, 1 is a laser (405
2) mask, 3 mirror, 4 objective lens (aperture 1.4), 5 oil, 6 PZT stage, 7 slide glass, 8 photosensitivity formed on the slide glass 7. Resist, 9 is a probe (cantilever), 1
Reference numeral 0 is a PZT scanner, 11 is a controller, 12 is a PC (personal computer), 13 is a condenser lens, 14 is a photodetector, and 15 is an observation device.

As described above, in the method of forming a pattern on the surface by irradiating the surface coated with the photosensitive resist 8 with the near-field light as an exposure light source, the probe 9 for generating the near-field light has a tip of 50 nm or less. And a solid metal probe, a dielectric probe, or a semiconductor probe. The curvature of the tip may be 50 nm or less. For example, the probe 9 is a cantilever in which silicon or silicon is coated with metal.

Here, it is desirable that the wavelength of the light irradiating the tip of the probe 9 is 450 nm or less and a blue semiconductor laser.

The wavelength of the light radiated to the tip of the probe 9 is 800 nm, and it is possible to use two-photon absorption to make it correspond to the absorption band of the photosensitive resist 8 near 400 nm. [Specific Example] A resist film is formed by spin coating on a positive type (Microposit S1800 manufactured by Shipley Co., Ltd.) glass substrate corresponding to g-line (436 nm) by a film thickness of 110 nm and prebaking at 100 ° C. for 25 minutes.

The distance between the tip of the probe and the resist film is 0-10.
nm (actually 0-several nm).

The probe is made of silicon and has a tip curvature of 20 nm.
Use the one. Since commercially available products have a thickness of 10 nm or less, finer processing can be performed by using ultrafine.

The laser power is varied from 5 to ²⁰ mJ / cm ² , and a 405 nm semiconductor laser is used.

An 800 nm laser may be used for two-photon absorption, and a 1200 nm laser may be used for three-photon absorption.

The probe scanning is 2.5 μm in the range of 25 μm square.
Draw lines with m pitch. At this time, the scanning speed is 25
μm is 143 ms (175 μm / s), 220 ms (1
14 μm / s).

Although a detailed description will be given later, as shown in FIG. 3, the energy of 10 to 10 mJ / cm ² is sufficient.
It is 0 nm wide, its profile is shown in FIG. 4, and a photograph of those multiple lines is shown in FIG.

As a comparative example, as shown in FIG. 6, when the near-field light is not used, a power of 35.7 mJ / cm ² or more is required and the minimum line width is 312 nm.

The following may be mentioned as application examples.

(1) Resist drawing in a semiconductor process (2) High-density recording can be performed in an optical memory by irradiation with a low-power blue laser, and in that case, polysilane that absorbs light at a wavelength near 400 nm can be used. .

(3) Photo-CVD As described above, the present invention is an atomic force microscope (AFM).
FIG. 3 shows a non-aperture type optical near-field fabrication using. By this technique, 100n is formed on the positive photoresist spin-coated on the glass substrate.
Directly pattern m lines. The nanostructure fabrication is performed using electric field enhancement (FE) generated at the tip end of the apertureless probe irradiated with laser light of 405 nm. As a result, it was observed that the line width of the produced line increased as the energy dose increased.

As described above, in the present invention, a nanometer photoresist line is formed in the vicinity of the laser-irradiated non-opening probe (cantilever) mounted on the atomic force microscope (AFM). With this technique, the limitation of the conventional scanning probe microscope can be overcome, and an apertureless probe of AFM or STM can be easily manufactured. When the AFM is used, since the electric field enhancement (FE) generated at the tip of the chip is used, the scanning speed is fast and the size and position can be accurately controlled. Furthermore, in addition to being inexpensive, it enables direct observation and correction of the resist pattern as demonstrated by other researchers. Unlike STM, AFM can be used with any type of material without unwanted exposure.

The device according to the invention, as shown in FIG. 1, is combined with a laser diode 1 of 405 nm A
It is composed of an FM and a focusing optical system for applying light to the apertureless probe (cantilever) 9. here,
The apertureless probe 9 used is several tens of nanometers (~ 2
It is made of 0 nm silicon and is used for both imaging and patterning. Spin-coat the photo-sensitive resist 8 on the slide glass 7 and apply 2 at 100 ° C
By heating for 5 minutes, a positive photoresist (Microposit S1800 manufactured by Shipley Co., Ltd.) having a film thickness of 110 nm was formed. In order to bring the focal point at a distance of several nanometers close to the photoresist,
The AFM was operated in tapping mode. This allows
The FE allows the threshold dose obtained from far field studies to be locally exceeded so that fabrication can begin. 25μm × 25μm, distance between lines 2.5μm
The resist was exposed by a raster scan of. The exposure dose was controlled by changing the scanning speed of the PZT stage 6 by the PC 12. By this method, different minute patterns can be drawn by simply changing the pattern program. The exposed sample was developed for 1 minute in each of the microposit developer and 17 MΩ of water.

FIG. 6 is a view showing a typical example of exposure characteristics of a photoresist obtained by exposure without using a near field.

As is clear from this figure, the width and depth of the resist increase as the exposure energy increases. This increase in energy is performed by slowing the scanning speed. Threshold energy dose is 35.7 mJ / cm
^{Is 2} . And the line width at this energy is 31
It is 2 nm, which is slightly narrower than 352 nm, which is a spot size calculated from the theory of diffraction and does not use a near field. No pattern was seen in samples exposed at doses below the threshold dose for photopolymerization at 35.7 mJ / cm ² without near field.

For the near field experiments of the present invention, the sample was exposed at a dose below the threshold dose. Due to the local FE effect at the tip of the chip, the threshold dose required for exposure can be increased and therefore photopolymerization of the resist is possible.

FIG. 3 shows the dependence of the sample resist thickness and depth on near-field exposure as a function of energy. Here, it is assumed that the FE at the tip of the tip is constant throughout the experiment.

As is clear from this figure, an increase in line width was observed as the energy increased.

Furthermore, no undesired exposures or changes in the samples after near-field exposure were observed. From these results, it is possible to accurately control the line width and the pattern position by simply changing the scanning speed (exposure time) or the laser power or moving the scanning stage. I understood.

FIG. 4 is an AFM image (2.5 μm × 2.5 μm) of a line pattern drawn using a non-aperture NSOM at different exposure times after development.

The inserted cross-sectional view clearly shows the line width and depth of the pattern. The exposure area is 2.5μ
It can be seen that it is composed of 10 parallel lines with a space of m, and the line width of each line changes by a difference of about 10 nm.

Further, the scanning rate (25 μm / 143 mse
When c) is calculated, it is approximately 175 μm / s. As described above, the scanning rate can be increased by increasing the scanning speed while increasing the laser power to compensate for the decrease in the exposure time.

Based on these results, the line width (~ 100 nm) of the surface of the drawn pattern is 5 to 10 times wider than the diameter of the apertureless probe, but is smaller than the calculated spot size without the near field. I found it narrow. This clearly shows that the produced pattern is due to the locally enhanced electric field.

In conclusion, the use of apertureless NSOMs for the first time investigated nanostructured fabrication in positive photoresists and showed a new method for producing patterns as small as 100 nm. In the near field experiment, an increase in the line width of the produced line was also observed.

As described above, the present invention has some promising features. That is, (1) it is cheaper and faster than any scanning probe microscope technique using an aperture probe.
(2) There is no unwanted exposure. (3) It has a high resolution and can accurately control size and position. (4) Direct observation and correction are possible. (5) In order to achieve high productivity and high resolution, it is possible to reduce the size of a parallel parallel ray having a high contrast (dense parallel ray).

Furthermore, this technique can also be used to study and clarify in detail the concept of a nanometer-sized light source in the near field of an illuminated apertureless metal tip.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention, and these modifications are not excluded from the scope of the present invention.

[0053]

As described in detail above, according to the present invention, the following effects can be achieved.

It is possible to configure the near-field optical lithography which is a development of a near-field microscope using a probe, which is small in size and can be controlled with high precision.

In particular, (a) it is cheaper and faster than any scanning probe microscope technique using an aperture type probe. (B) No unwanted exposure. (C) It has a high resolution and can accurately control size and position. (D) Direct observation and correction are possible. (E) Simultaneous drawing with a cantilever array is possible to achieve productivity and high resolution.

[Brief description of drawings]

FIG. 1 is a schematic view of essential parts of a near-field lithography apparatus showing an embodiment of the present invention.

FIG. 2 is an overall schematic diagram of a near-field lithography apparatus showing an embodiment of the present invention.

FIG. 3 shows the dependence of sample resist thickness and depth on near-field exposure as a function of energy.

FIG. 4 is a diagram showing the profile of FIG. 3;

FIG. 5 shows a photograph of those multiple lines of FIG.

FIG. 6 shows the dependence of the sample resist thickness and depth on exposure as a function of energy, without near-field exposure.

[Explanation of symbols]

1 laser (405 nm) 2 mask 3 mirror 4 Objective lens (aperture 1.4) 5 oil 6 PZT stage 7 Slide glass 8 Photosensitive resist 9 probe (cantilever) 10 PZT scanner 11 controller 12 PC (personal computer) 13 Condensing lens 14 Photodetector 15 Observation device

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B23K 101: 40 H01L 21/30 502D

Claims (10)

[Claims] 1. A pattern forming method using near-field light, wherein a surface coated with a photo-sensitive resist is irradiated with near-field light as an exposure light source to form a pattern, wherein the tip for generating the near-field light has an extremely fine tip. Is disposed on the surface of the photo-sensitive resist, and the near-field light whose electric field is enhanced by irradiating and converging a laser beam on the tip of the probe to the photo-sensitive resist is used. Pattern formation method using near-field light. 2. The pattern forming method using near-field light according to claim 1, wherein the laser light is blue semiconductor laser light, and the photo-sensitive resist is irradiated from the back surface or the side surface.
A pattern forming method using near-field light, which is characterized by converging. 3. The method for forming a pattern by near-field light according to claim 1, wherein a probe having an extremely thin tip for generating the near-field light is arranged on the surface of the photosensitive resist, A near-field light pattern forming method, characterized in that near-field light whose electric field is enhanced by irradiating and converging a blue semiconductor laser light on the tip from the back side of the photosensitive resist. 4. The pattern forming method using near-field light according to claim 1, wherein the probe is a cantilever having a tip curvature of 50 nm or less. 5. The near-field pattern forming method according to claim 3, wherein the probe is made of a metal, a dielectric or a semiconductor. 6. The method for forming a pattern by near-field light according to claim 4, wherein a silicon cantilever is used to apply a g-line resist having a thickness of 100 nm as the photosensitive resist, and a 405 nm blue semiconductor laser light is used for drawing. A method of forming a pattern by near-field light, comprising: 7. The method for forming a pattern using near-field light according to claim 6, wherein the patterning speed is 5 to 5 μm per second.
Low power of 10 mJ / cm ² , width 100 nm, depth 10
A method for forming a pattern by near-field light, which comprises drawing a plurality of nm lines. 8. A near-field light pattern forming apparatus for forming a pattern by irradiating a surface coated with a photo-sensitive resist with near-field light as an exposure light source, comprising: (a) being arranged on the surface of the photo-sensitive resist; A near-field device comprising: a probe having an extremely thin tip for generating the near-field light; and (b) a laser beam irradiation device for irradiating and converging the photo-sensitive resist on the tip of the probe. Light patterning device. 9. The near-field light pattern forming apparatus according to claim 8, wherein the probe is a cantilever having a tip curvature of 50 nm or less. 10. The pattern forming apparatus using near-field light according to claim 9, wherein the probe is made of a metal, a dielectric, or a semiconductor.