JPH0823602B2 - Method for manufacturing die for press-molding diffraction grating and method for manufacturing diffraction grating - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily and mass-producing diffraction gratings of various shapes, which is one of high-precision optical elements subjected to fine processing. .

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, as shown in “NIKKEI MECHANICAL” 1985.6.17, P.85, other resists are formed in a line on the resist at equal intervals, and the oblique etching is performed physically by ion flow and sawing. There has been proposed a method of processing a resist in a blade shape, 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.

However, in these methods, it takes a very long time to work on one diffraction grating, and there is a problem in reproducibility, and it is very difficult to manufacture 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 a soft material such as a resist, it lacks 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, according to the present invention, a base material is a cemented carbide containing tungsten carbide (WC) as a main component, titanium nitride (TiN), or titanium carbide (Ti).
C), chrome carbide (Cr ₃ C ₂ ) or alumina (Al
₂ O ₃ ) is used as the main component, and platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), osmium (Os), ruthenium (Ru),
Rhenium (Re), Tungsten (W), Tantalum (Ta)
Among them, a photosensitive resin is applied to the surface of a press molding flat mold of an optical element formed by coating an alloy thin film containing at least one kind of metal, and a line-and-space pattern is formed at appropriate intervals. While changing the incident angle with respect to the ion flow, the entire surface is physically etched uniformly to form a diffraction grating of the desired shape on the coated alloy thin film, and a press molding die is produced. Then
By press molding glass using the mold,
By making a glass diffraction grating by transferring a diffraction grating of a desired shape onto the glass surface, it is possible to easily and reproducibly produce a large number of diffraction gratings with excellent durability. Is.

Action The present invention produces a press-molding die for an optical element that has been subjected to microfabrication by the above-described method, and by using this die, a high-precision optical element having good optical performance is directly pressed to form a large amount. It made it possible.

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

Example 1 First, a cemented carbide mainly composed of WC having a diameter of 20 mm and a thickness of 6 mm was used as a base material, and the surface of this mold was mirror-polished using ultrafine diamond abrasive grains. Next, a Pt-Ru alloy thin film having a thickness of 5 μm was coated as a protective film on the mirror surface by a sputtering method to prepare a planar press molding die. FIG. 1 shows a cross-sectional structural diagram of the unprocessed press-molding die thus constructed. In FIG. 1, 11 is a base material and 12 is a protective film.

Next, PMMA (polymethylmethacrylate) resin was spin-coated on the flat surface shown in FIG.
After forming a film with a thickness of 0.5 μm and prebaking at 120 ° C. for 20 minutes, a line-and-space mask pattern with a line width of 1 μm was printed on the resin by a contact exposure method using an excimer laser as a light source for development. In this manner, a line-and-space pattern having a line width of 1 μm and a step of 0.5 μm was formed on the surface of the flat mold with PMMA resin. A sectional view in this state is shown in FIG. In FIG. 2, 21 is a base material, 22 is a protective film, and 23 is PMMA resin.

This mold 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. 3 shows a schematic diagram of this ECR plasma ion shower etching apparatus. In FIG. 3, 31 is EC
An R plasma generator, 32 is an ion extraction electrode, 33 is a shutter, 34 is a substrate holder whose tilt angle is controllable, and 35 is an exhaust device. Initially, the mold was set at right angles to the ion flow, but when the substrate tilt angle controller was turned on, the substrate tilt angle changed 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. FIG. 4 shows a cross-sectional view of a die for press-molding a diffraction grating manufactured by this method. In FIG. 4, 41 is a base material, 42 is a protective film, and 43 is a sectional shape of the processed diffraction grating. As is clear from FIG. 4, when the angular velocity is constant, 2 μm
It can be seen that a press-molding die for a symmetrical wave-shaped diffraction grating with a pitch of 0.8 μm is obtained.

As another example, etching was performed until the PMMA resin was completely etched by changing the angular velocities greatly at the substrate inclination angles of 45 ° to 90 ° and 90 ° to 135 ° with respect to the ion flow. FIG. 5 shows a sectional view of a die for press-molding a diffraction grating manufactured by this method. In FIG. 5, 51 is the base metal,
Reference numeral 52 is a protective film, and 53 is a sectional shape of the processed diffraction grating.
As is clear from FIG. 5, when the angular velocity of the substrate with respect to the ion flow is greatly different from 45 ° to 90 ° and from 90 ° to 135 °, the pitch is constant at 2 μm, but the wave top is It can be seen that a press-molding die for a wave-shaped diffraction grating that is biased to the left or right is obtained.

As described above, by changing the angular velocity of the substrate tilt angle with respect to the ion flow, the wave shape of the press mold of the diffraction grating can be controlled. Further, by changing the line and space pattern of the PMMA resin formed on the surface of the flat mold before etching, it is possible to control the pitch and step of the press mold of the diffraction grating.

Therefore, according to the method of the present invention, it is possible to obtain a press mold of a high-strength and heat-resistant diffraction grating for easily and reproducibly manufacturing a glass diffraction grating having excellent durability. I can do it now. In Example 1, a mold using a cemented carbide containing WC as a main component as a base material and a Pt-Ru alloy thin film as a protective film was shown, but the base material contains WC as a main component. Even if a cermet mainly composed of titanium nitride (TiN), titanium carbide (TiC), chromium carbide (Cr ₃ C ₂ ) or alumina (Al ₂ O ₃ ) having the same strength as cemented carbide is used,
Further, as the protective film, platinum (Pt) and palladium (Pt), which have durability against glass press, are used similarly to the Pt-Ru alloy thin film.
d), iridium (Ir), rhodium (Rh), osmium (Os), ruthenium (Ru), rhenium (Re), tungsten (W), tantalum (Ta) alloy thin film containing at least one metal. It goes without saying that the same mold can be obtained by using.

Further, although ECR plasma ion shower etching was used as the physical etching method in Example 1, the same effect can be obtained by using an etching method such as reactive ion etching, reactive ion beam etching or sputter etching. It goes without saying that it will be done.

Example 2 An example in which a glass diffraction grating was manufactured by press-molding a mold shape on a glass surface using a press molding mold for a diffraction grating that could be manufactured by the method shown in Example 1 will be shown. .

The die shown in FIGS. 4 and 5 of Example 1 was used as the upper die, and the flat die in which the Pt-Ru alloy thin film was coated on the cemented carbide was used as the lower die, and the press shown in FIG. 6 was used. Set in the molding machine. In FIG. 6, 61 is an upper mold fixing block, 62 is an upper mold heating heater, 63 is an upper mold, 64 is flat glass, 65 is a lower mold, 66 is a lower mold heating heater, and 67 is a lower mold fixing. Block, 68 is upper mold thermocouple, 69 is lower mold thermocouple, 61
0 is a plunger, 611 is a positioning sensor, 612 is a stopper, and 613 is a cover.

Next, a disc-shaped flat glass plate 64 with a radius of 10 mm and a thickness of 2 mm, which is composed of 70% by weight of lead oxide (PbO), 27% by weight of silica (Si0) and the balance of trace components, is used as a lower mold for the upper and lower molds 63 and 65 Place on top of 65, place the upper mold 63 on it, raise the temperature to 520 ℃ as it is, press it in a nitrogen atmosphere with a pressing pressure of about 40 kg / cm ² and hold for 2 minutes, then keep it up and down as it is The mold is cooled to 300 ° C., the press-molded glass diffraction grating is taken out, and the glass diffraction grating molding process is completed.

By repeating the above steps, at the end of the 10000th press, remove the upper mold 63 from the press molding machine, observe the state of the press surface with an optical microscope, and measure the surface roughness (RMS value, Å) of the press surface at that time. It was measured and the mold precision was evaluated.

The results of the press test are shown in Table 1. Like sample Nos. 1 and 2, the molds made here had surface roughness (RMS value) of 11.5Å even after 10,000 presses.
It can be seen that at 11.4Å there was almost no roughness and the mold shape did not change.

As described above, according to the present invention, it becomes possible to easily manufacture a highly precise glass diffraction grating by press molding in a large amount.

Effects of the Invention According to the method of the present invention, it becomes possible to produce a mold for press-molding a glass diffraction grating having a desired shape, and by using this mold, a glass diffraction grating having excellent durability. It has become possible to fabricate easily and in large quantities.

[Brief description of drawings]

1, FIG. 2, FIG. 4 and FIG. 5 are schematic views of a cross section of a press molding die for a diffraction grating of the present invention, FIG. 3 is a schematic view of an ECR plasma ion shower etching apparatus, and FIG. It is a schematic diagram of a press molding machine incorporating a press molding die for a diffraction grating in an example. 11 …… Base material, 12 …… Protective film.

Continuation of the front page (56) References JP-A-60-186806 (JP, A) JP-A-56-113108 (JP, A) JP-A-50-155202 (JP, A)

Claims (2)

[Claims] 1. A base material is a cemented carbide mainly composed of tungsten carbide (WC) or titanium nitride (Ti).
N), Titanium Carbide (TiC), Chrome Carbide (Cr
₃ C ₂ ) or alumina (Al ₂ O ₃ ) as the main component is used, and platinum (Pt), palladium (Pt)
d), iridium (Ir), rhodium (Rh), osmium (Os), ruthenium (Ru), rhenium (Re), tungsten (W), tantalum (Ta) alloy thin film containing at least one metal. The photosensitive resin is applied to the surface of the press-molding flat mold of the optical element formed by coating, to form a line-and-space pattern at equal intervals, and the incident angle changes over time with respect to the ion current. A method for producing a die for press-molding a diffraction grating, which comprises physically etching the whole while uniformly forming a diffraction grating having a desired shape on the coated alloy thin film. 2. The base material is a cemented carbide mainly containing tungsten carbide (WC) or titanium nitride (Ti).
N), Titanium Carbide (TiC), Chrome Carbide (Cr
₃ C ₂ ) or alumina (Al ₂ O ₃ ) as the main component is used, and platinum (Pt), palladium (Pt)
d), iridium (Ir), rhodium (Rh), osmium (Os), ruthenium (Ru), rhenium (Re), tungsten (W), tantalum (Ta) alloy thin film containing at least one metal. The photosensitive resin is applied to the surface of the flat mold for press molding of the optical element formed by coating, to form a line-and-space pattern at equal intervals, and the incident angle changes with time with respect to the ion current. While uniformly performing physical etching on the whole, forming a diffraction grating of a desired shape on the coated alloy thin film, using a mold for press molding of the diffraction grating, the flat glass is heated and pressed. A method for producing a diffraction grating, which comprises producing a diffraction grating made of glass by transferring the diffraction grating to the surface of flat glass.