JPS6180822A - Manufacture of blazed diffraction grating - Google Patents

Abstract

PURPOSE:To obtain the method for manufacture of a highly precise blazed diffraction grating to be formed on an Si substrate by a method wherein a line-and-space is formed on a (100)Si single crystal substrate using a mask material, an etching having a vertical cross-section is performed using an Si anisotropic etchant. CONSTITUTION:A mask 12 is formed on a (100)Si substrate 11. A lithographic technique, wherein a resist is used, is utilized in forming a line-and-space using a mask material. An etching groove 13 having a vertical cross-section is formed on the (100)Si substrate 11 by performing a dry etching. Then, when an anisotropic etching is performed using hydrazine, a (111) plane appears on the side wall, the (111) plane on the side walls of both line-and-spaces are connected, the SiO212 which is a mask material is removed by exfoliation, and a blazed diffraction grating is formed on the part where the SiO212 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for making a blazed diffraction grating for a light source.

(Prior art) Conventionally, diffraction gratings have been fabricated using an etching method (A, Frank et al.
Ph1l.

Trans, Roy, Soc, 277 (1975) 5
03-) and, in particular, by mechanical polishing.

(Problems to be Solved by the Invention) However, when using the etching method, it is easy to fabricate using a so-called 5tO2 glass plate, which has good workability due to its selectivity with the mask material, and it is not possible to fabricate it on an 81 substrate. It was difficult. However, when the energy of the light source becomes high, the heat is easily absorbed by the 5to2, and the 81 board, which has good heat conduction, becomes much more advantageous.

On the other hand, in the mechanical polishing method, as is intuitively understood, scratches are created using something like a file, which has serious drawbacks in the finish of the surface and processing accuracy, and there is a lot of stray light.

An object of the present invention is to provide a method for producing a high-quality blazed diffraction grating on an 81 substrate by eliminating such conventional drawbacks.

(Means for Solving the Problems) The present invention involves creating lines and spaces on a (100) St single crystal substrate using a mask material, etching the lines to have a vertical cross section using a dry etching method,
This is a method for producing a blazed diffraction grating, which is characterized in that a blazed diffraction grating is produced by etching as it is with an anisotropic etching solution of St.

(Function) The present invention solves the problems of the prior art by adopting the above configuration. First, a mask material of 810 m is formed on a (100) Si substrate, and a line-and-strip is formed by a lithography technique using renost. Thereafter, the renost is masked off and the SIO is etched by a dry etching method. Etching conditions at this time may be fluorine-based gas or chlorine-based gas. or,
There is no problem with ion milling or parallel plate etching equipment. Next, using the 5iO1 formed here as a mask material, the amount of S is etched by a dry etching method. This may be an etching condition with a vertical cross section. Further, there is no problem even if only the gas is changed in the same apparatus and etching is performed without removing the Lennost mask. next,
With 5i02 lines and spaces (100)
Etching is performed on the Si substrate using an anisotropic etching solution. As the etching solution, hydrazone, KOI (etc.), which has a fast etching speed for the (100) plane, can be used.
The plane orientation is also carved on the i-side wall. In other words, also on the side wall (
111) surface dryer, the (111) surface is also polished on the etched surface. The (111) plane appearing on this side wall is 1
The (111) face-to-to-connection that appeared on the side wall of the next line and space, 5102 which is the mask material,
It peels off, leaving behind a diffraction grating with (111) sidewalls.

(Example) Examples of the present invention are shown below. First, as shown in FIG. 1(a), a mask 12 is formed on a (100) Si substrate 11 using 5IO-a. This mask material does not need to be 5tot, but 5iO1 is considered to be easy to use.

The lines and spaces created by this mask material were created using lithography technology using renost.

The effects of the present invention do not depend on the method of forming lines and spaces using this mask material. Next, as shown in Figure 1(b), 1 (100
) Etching groove 13 having a cross section perpendicular to the Si substrate 11
Create. In this example, cct, F' + o,
The etching process used the stow mask 12.
Any condition is sufficient as long as the (100) Si substrate 11 is the object to be etched. Next, as shown in Fig. 1(c), when anisotropic etching is performed using hydranone, (111) planes appear on the side walls, and among them, the (111) planes on the side walls of both lines and spaces meet. The 5iO212 mask material is peeled off and removed, and later the first mask material is removed.
A glazed diffraction grating is formed as shown in Figure (d). In this example, hydrazine was used, but KOH etc.
11) As long as the etching solution is such that the plane appears on the (100) Si substrate.

Next, the relationship between the depth of etching, the pitch of lines and lines, and the wavelength of the glaze will be explained using Fig. 2.
If the width of the mask 12 is a and the width of the etched surface is b, then the (111) plane is 54.74mm compared to the (100) plane.
Because of the tilt, surfaces having the angles shown in FIG. 2 appear. The following equation can be obtained as a condition for connecting both line and space forces by etching with hydrazine.

a = 0941...(1) That is,
Dry etching depth t(1') 0.94 times is 5i
It is sufficient that the width of the mask 12 of 02 is a. On the other hand, the primary blaze wavelength λb is expressed by the following equation, assuming that the pitch is a+b in this case, the blaze angle is 54.74°, and the incident angle is α.

Circle = 2 (a+b) gin (54, 74 x cm (
θ-54.74°) - (2) When the incident angle α is set to 75° and is combined with the condition of equation (1), the following equation is obtained.

λb=1.54(a+b)...
(3) That is, when the present invention is applied to the above idea, since a=0.5 μm5b=0.5 μm1 in the example, λl=1.54 μm. Further, the dry etching depth t is 0.53 μm. The subsequent etching depth with hydrazine was 15,000X per minute.
It is. However, since the (111) plane appears and the (100) plane disappears, and the etching does not proceed any further, hydranone etching may be performed until the 5i0212 mask 12 is sufficiently peeled off.

(Effects of the Invention) The blazed diffraction grating produced by the method of the present invention can easily obtain any glaze wavelength by simply changing the width of the lines and spaces and the dry etching depth. It can be easily fabricated on a St substrate, which has been considered difficult to achieve with conventional technology, and has excellent heat dissipation, making it effective for high-output light sources.

In addition, the glazed wavelength can be determined by dry etching and etching, and the dimensional accuracy is good.Finally, the (100) Si substrate is anisotropically etched and etched with tinda liquid, so the diffraction surface has extremely flatness. Therefore, it is possible to create a diffraction grating with less stray light.

[Brief explanation of the drawing]

FIGS. 1(a) to (d) are diagrams showing examples of the present invention in the order of steps, and FIG. 2 is a diagram showing the principles and conditions of the present invention. 11... (100) Si substrate, 1.2... Mask, 13... Machining, groove. Patent applicant NEC Corporation - Figure 1 Figure 1 (d)

Claims (1)

[Claims] (1) Lines and spaces of mask material are created on a (100) Si substrate, vertical etching is performed using a dry etching method, and then a blazed diffraction grating is created using an anisotropic Si etching solution. How to create a blazed diffraction grating.