JPS6033503A - Production of blazed grating - Google Patents

Abstract

PURPOSE:To obtain a blazed grating having high quality by forming a layer insoluble in a solvent for photoresist on the surface of an org. high polymer film, forming a relief grating on the photoresist film coated thereon and etching said film with a diagonal-incident ion beam. CONSTITUTION:An electron ray resist film 2 is coated on a substrate as an org. high polymer film and the film 2 is etched with an argon ion beam then a layer 3 insoluble in a solvent for photoresist is formed on the surface thereof. Photoresist 4 having an ion etching rate lower than the film 2 is coated on said insoluble layer 3. A relief grating is then formed on the photoresist film. Such sample is ion-etched with a diagonal-incident argon ion beam by using an ion etching device. The blazed grating of transmission type having high quality is obtd. by such method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a blazed grating used as a wavelength dispersion element or hologram element in a spectrometer.

Diffraction gratings are used in various applications such as wavelength dispersion elements in spectrometers and hologram elements, such as holographic scanners,
There are holographic lenses, etc., but they generally have low diffraction efficiency and are a practical problem. Blazed gratings have the characteristic of being able to diffract 10,096 beams of light into a specific diffraction order.
Manufacturing is difficult because the shape of the lattice grooves must be controlled. Currently, the method that seems to be practical for etching rings is to ion-etch the substrate with an ion beam from an oblique direction using a relief grating made in advance as a shadow mask. Currently known methods for this method include using gallium arsenide as the substrate or polymethyl methacrylate (PMMA) coated on a glass plate, but the former is expensive because it is a crystal, and it is opaque and therefore transparent. There is a drawback that a molded grid cannot. On the other hand, in the latter case, even if the PMMA coated on the glass plate is sufficiently dried, the solvent of the photoresist is used to form a relief grid on the coating film.
Since the MMA film easily dissolves and becomes compatible with each other, the relief grating itself cannot be made of good quality, and therefore a good quality blazed grating cannot be manufactured.

The object of the invention is to provide a method for producing a high-quality blazed grating of the transmission type, which eliminates the above-mentioned drawbacks.

The method for manufacturing a blazed grating of the present invention includes a step of applying an organic polymer film to a substrate, a step of irradiating the applied organic polymer film with an ion beam, and a step of applying an ion beam to the organic polymer film irradiated with the ion beam. a step of applying a photoresist having a slow ion etching rate as well as the organic polymer film;
forming the applied photoresist film into a relief-type diffraction grating, and using the diffraction grating as a shadow mask,
This method of manufacturing a blazed grating is characterized in that it includes a step of performing ion etching with an ion beam from an oblique direction with respect to a substrate.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 to FIG. 6 are cross-sectional views for explaining one embodiment of the present invention in the order of steps. Figure 1 shows the substrate 1
FIG. 2 is a cross-sectional view showing a state in which an organic polymer film 2 is applied to the substrate.

A glass plate and an acrylic plate were used as the substrate. As the organic polymer film, after various experiments, we used electron beam resist 5EL-N manufactured by Somar Kogyo Co., Ltd., which has a fast ion etching speed.
Type A was used. 5EL-N Type A is a comonomer of glycidyl methacrylate and ethyl acrylate. The ion etching rate was 660 angstroms/min for a 1 mA/i argon ion beam. The coating was applied to the substrate using a spinner. The coating thickness is approximately 1 μm. Thereafter, in the case of a glass substrate, baking was performed at 80° C. for 30 minutes. When using an acrylic board, baking was performed for 60 minutes at a temperature of 50%. Next, this mechanical polymer membrane was accelerated by an amount of JfE50.
Ion etching was performed for about 1 minute using an argon ion beam at 0 V and an ion current density of 0.5 mA/c-. As a result, as shown in FIG. 2, a layer 3 insoluble in the solvent of photoresist AZ-1350J was formed on the surface of the organic polymer film.

, FIG. 3 is a sectional view showing a state in which a photoresist 4 is applied on the insoluble layer 3. As the photoresist, AZ-1350J manufactured by Shipley was used. The ion etching rate is aOO! for 1 mA/d argon ion! 15
) Met. The coating was applied onto the electron beam resist g using a spinner. I! ig! The i-squeezing was performed under the same conditions as the electron beam resist. The coating thickness was 90.3 μm to 1 pm, which varied depending on the pitch of the lattice to be formed next.

Next, in order to form a relief grating on the photoresist film, interference fringes were formed on the photoresist film using an interferometer using a He-Cd laser as a light source, and the film was developed with a developer. FIG. 4 is a sectional view showing the state after development. A relief grating as shown in FIG. 4 can also be formed by contact printing using a laser interferometer and an emulsion mask. Next, the sample shown in FIG. 4 was ion-etched using an ion etching apparatus with an obliquely incident argon ion beam. FIG. 5 shows a state in which ion etching is interrupted midway. When ion etching is further carried out, a blazed grating as shown in FIG. 6 is obtained. The argon ion beam was used at an acceleration voltage of 300 to 700 V and an ion current density of 0.3 to 0.7 mk/c.

In this example, 5EL-N type A is used as the organic polymer film.
Although we have explained the case using h=
Examples of molecular materials include electron beam resist ERR-9, which is similar to 5EL-N type A, or an electrolyte (electron beam resist C0P) in which the two methyl groups of methacrylic acid are replaced with C4 and CI (CF), Or polymethyl methacrylate (PMMA), or polymethods can produce blazed grids.

As described above, it is a cross-sectional view showing a high quality transmission type according to the present invention.

In the figure, 1 is a substrate, 2 is an organic polymer film, 36- 4 represents a silent layer, and 4 represents a photoresist.

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Claims (1)

[Claims] a step of applying an organic polymer film to a substrate; a step of irradiating the applied organic polymer film with an ion beam; and ion etching the organic polymer film irradiated with the ion beam. A step of applying slow photoresist, a step of forming the applied photoresist film into a relief type diffraction grating, and a step of ion etching with an ion beam from an oblique direction to the substrate using the diffraction grating as a shadow mask. A method for manufacturing a blazed lattice, comprising: