JPH0823601B2 - Diffraction grating fabrication method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for directly manufacturing a diffraction grating of various shapes on a glass or aluminum surface, which is one of highly precise optical elements subjected to fine processing. Is.

Conventional technology In order to manufacture a highly accurate diffraction grating, very fine processing is required. Conventionally, a diffraction grating has been produced by forming grooves one by one on the surface of a soft material by machining. However, with such a method, the interval between the grooves is limited to several μm, and submicron processing cannot be performed.

Therefore, recently, a processing method applying semiconductor technology has been studied.

For example, "NIKKEI MECHANICA
L) ”1985.6.17, p.85, another resist is formed in a line on the resist at equal intervals, and is obliquely etched physically by an ion flow to form a saw blade. There has been proposed a method of processing a resist, a method of forming a hologram diffraction grating on a resist by a two-beam interference exposure method, as shown in Japanese Patent Application No. 62-331972.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, with these methods, it takes a very long time to produce one diffraction grating, and there is a problem in reproducibility, and it is very difficult to produce the same one in a large amount. However, it takes much time and cost to manufacture.

Further, since the diffraction grating manufactured by these methods is made of a soft material such as a resist, there is a problem that it lacks in durability.

In view of the above problems, the present invention aims to directly form a diffraction grating of a desired shape on the surface of a high-strength material by a physical method.

Means for Solving the Problems In order to solve the above problems, in the present invention, a photosensitive resin is applied to the surface of flat glass or flat aluminum,
A line-and-space pattern is formed at equal intervals, and the entire surface is uniformly physically etched while changing the incident angle with respect to the ion flow, and the desired shape is obtained on the surface of flat glass or flat aluminum. The diffraction grating having excellent durability can be easily and reproducibly manufactured by forming the diffraction grating.

Effect In the present invention, since the diffraction grating having a desired shape is directly formed on the surface of the flat glass plate or the flat aluminum plate by the above-described method, it becomes possible to manufacture a diffraction grating having extremely excellent durability.

Further, the line-and-space pattern formed of the photosensitive resin has good reproducibility and the same pattern can be drawn. Therefore, when the changes over time in the substrate tilt angle are the same, diffraction gratings of exactly the same shape can be obtained. Therefore, according to the present invention, a diffraction grating having excellent durability can be easily and reproducibly manufactured by the above method.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, the surface of a flat glass plate having a thickness of 30 mm × 30 mm and a thickness of 2 mm was mirror-polished using ultrafine diamond abrasive grains.

Next, PMMA (polymethylmethacrylate) resin was spin-coated to a thickness of 0.5 μm on the surface of flat glass that had been polished to a mirror surface, prebaked at 120 ° C for 20 minutes, and then the line width was changed using an excimer laser as a light source. A 1 μm line-and-space mask pattern was baked on the resin by a contact exposure method and developed. In this way, a line-and-space pattern having a line width of 1 μm and a step of 0.5 μm was made of PMMA resin on the surface of the flat glass. A sectional view in this state is shown in FIG. In FIG. 1, 11 is a flat glass substrate and 12 is PMMA resin.

This substrate was set in an ECR (electron cyclotron resonance) plasma ion shower etching device capable of changing the angle with respect to the ion flow with time. FIG. 2 shows a schematic diagram of this ECR plasma ion shower etching apparatus. In FIG. 2, 21 is EC
An R plasma generator, 22 is an ion extraction electrode, 23 is a shutter, 24 is a substrate holder whose tilt angle is controllable, and 25 is an exhaust device. Initially, the substrate is set at right angles to the ion flow, but when the substrate tilt angle controller is switched on, the substrate tilt angle changes over time with respect to the ion flow as programmed in the controller. In this embodiment, the substrate tilt angle was changed variously with time from 45 ° to 135 ° with respect to the ion flow.

First, as a first example, etching was performed at a constant angular velocity until the PMMA resin was completely etched. A cross-sectional view of the glass diffraction grating produced by this method is shown in FIG. In FIG. 3, reference numeral 31 is a glass substrate, and 32 is a sectional shape of the processed diffraction grating. As is clear from FIG. 3, when the angular velocity is constant, the step difference is 2 μm pitch.
It can be seen that a wave-shaped glass diffraction grating having a symmetrical shape at 0.8 μm is obtained.

As another example, etching was performed until the PMMA resin was completely etched by greatly changing the angular velocity when the substrate tilt angle with respect to the ion flow was 45 ° to 90 ° and 90 ° to 135 °. A cross-sectional view of the glass diffraction grating produced by this method is shown in FIG. In FIG. 4, 41 is a glass substrate, 42
Is the cross-sectional shape of the processed diffraction grating. As is clear from FIG. 4, the substrate tilt angle with respect to the ion flow is 45 ° to 90 °.
When the angular velocities are significantly different from 90 ° to 135 ° up to °, the pitch is constant at 2 μm, but it is possible to obtain a wave-shaped glass diffraction grating with the wave vertices biased to the left or right. Recognize.

By thus changing the angular velocity of the substrate tilt angle with respect to the ion flow, the wave shape of the diffraction grating can be controlled. Further, the pitch and step of the diffraction grating can be controlled by changing the line and space pattern of the PMMA resin formed on the surface of the flat glass before etching.

Therefore, the method of the present invention makes it possible to easily manufacture a diffraction grating made of glass having excellent durability and with good reproducibility.

In the examples, the method for manufacturing the diffraction grating made of glass was shown, but a material that can be physically etched,
For example, it goes without saying that a diffraction grating can be easily and reproducibly manufactured by the method of the present invention even if an aluminum substrate or the like is used. Also, in the embodiment,
Although ECR plasma ion shower etching was used as the physical etching method, reactive ion etching,
Needless to say, the same effect can be obtained by using an etching method such as reactive ion beam etching or sputter etching.

EFFECTS OF THE INVENTION By the method of the present invention, a diffraction grating having a desired shape can be easily and reproducibly manufactured directly on glass or aluminum, and a diffraction grating having excellent durability can be obtained. It was

[Brief description of drawings]

1 is a cross-sectional view of the glass substrate before etching, and FIG. 2 is
Schematic diagram of ECR plasma ion shower etching equipment,
3 and 4 are cross-sectional views of a glass diffraction grating manufactured by the method of the present invention. 11 …… Flat glass substrate, 12 …… PMMA resin.

Claims (1)

[Claims] 1. A photosensitive resin is applied to the surface of a flat glass plate or a flat aluminum plate to form a line-and-space pattern at equal intervals, and while changing the incident angle with respect to the ion flow, the whole is covered. A method for producing a diffraction grating, which comprises physically and uniformly etching to form a diffraction grating having a desired shape on the surface of flat glass or flat aluminum.