JPH03139602A - Production of grating pattern - Google Patents

Abstract

PURPOSE:To form fine patterns with good controllability by irradiating a substrate with a focused ion beam from the direction inclined by a specific angle to selectively generate lattice defects in the substrate in the regions irradiated with the ion beam and selectively etching away the regions irradiated with the ion beam. CONSTITUTION:The substrate 1 is irradiated with the focused ion beam 5 from the direction inclined by the angle larger than theta in the direction perpendicular to the substrate 1 when the average value of the range of the ion beam in the substrate 1 is RP, the average value of the spread in a transverse direction is DELTAX and theta is the value derived from tantheta=RP/DELTAX. The lattice defects are generated only in the regions 6 irradiated with the ion beam in the substrate 1 and the regions 6 irradiated with the ion beam are selectively etched away by the wet etching. The controllability of shape working is improved in this way and the fine lattice patterns are formed. The influence by the intrasurface nonuniformity of a resist is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a grating pattern used in optical elements and the like.

[Conventional technology]

In terms of efficiency, it is desirable that the cross-section of a grating pattern used in an optical element or the like has an asymmetrical shape as shown in FIG. 4fdl. A conventional method for forming such a lattice pattern will be explained with reference to FIG.

First, a resist pattern 2 is formed on a substrate 1 using photolithography (FIG. 4(a)).

Next, the ion beam shower 3 is irradiated from an oblique direction (FIG. 4(b)).

By ion beam irradiation, the parts not covered by the resist are etched, and the resist pattern is also etched.
It is notched and decreases (Fig. 4 (C)).

As etching progresses, an asymmetrical lattice pattern is formed as the resist pattern decreases (see Figure 4).
d)).

Problems to be solved by invention C] In such a conventional manufacturing method, the following ■.

There was a problem as shown in ■.

■There is a limit to the resolution of the photolithography process for forming resist patterns, making it difficult to form lattice patterns with fine shapes and poor controllability.

(2) Since the resist pattern does not necessarily decrease uniformly, the in-plane uniformity of the lattice pattern shape is not good.

The present invention has been made in view of these points, and its purpose is to provide good controllability of shape processing, enable the formation of fine lattice patterns, and further reduce in-plane non-uniformity of the resist. An object of the present invention is to obtain a method for manufacturing a lattice pattern that is not affected by gender.

[Means to solve the problem]

In order to solve such problems, the present invention provides that the average value of the range of the ion beam in the substrate is R2, the average value of the lateral spread is ΔX, and θ is tanθ=Rp/ΔX.
When the value is derived from The ion beam irradiation area is selectively etched away by wet etching.

[Effect]

In the method for manufacturing a grating pattern according to the present invention, the processed shape is defined with high precision by physical values such as the range of the ion beam.

〔Example〕

An embodiment of the method for manufacturing a lattice pattern according to the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a distribution diagram showing the lattice defect distribution that occurs in the substrate when the substrate is irradiated with a focused ion beam from a direction perpendicular to the substrate. In the figure, 1 is the substrate, 5 is the focused ion beam, and 6 is the lattice defect distribution. Defect distribution (ion beam irradiation area).

FIG. 2 is a distribution diagram showing the lattice defect distribution generated in the substrate when the substrate is irradiated with a focused ion beam from a direction inclined by θ, where 1 is the substrate, 5 is the focused ion beam,
6 is the lattice defect distribution.

FIG. 3 is a pattern diagram showing a lattice pattern formed by wet etching the sample shown in FIG. 2, and 4 is a lattice pattern diagram.

Next, each figure will be explained in more detail.

A 200 keV nitrogen (N'') ion beam 5 with a diameter of 0.
The focused ion beam 5 is focused to 1 μm, and the focused ion beam 5 is
Lattice defect distribution that occurs when z substrate I is irradiated perpendicularly 6
is shown in Figure 1. In the figure, the closer the diagonal lines are, the higher the lattice defect density is.

The average range of the ion beam 5 (indicates the highest lattice defect density at the depth of liRP. Also, the average value of the lateral spread of the ion beam is ΔX. The 200 keV N+ ion beam 5 is When irradiated with Rp
= 0.43 pm, ΔX = 0.14 μm.

Here, RP/ΔX=0.4310.14=3.07=
When the focused ion beam 5 is incident on the substrate 1 from a direction tilted from the normal direction of the substrate 10 (the direction of the - dotted chain line) by θ (#72°) that is tanθ, lattice defects as shown in FIG. Distribution 6 results.

Next, when the substrate 1 is immersed in hydrochloric acid for 10 minutes, the lattice defect generation region 6 generated by the ion beam irradiation is selectively etched away, and a sawtooth asymmetric lattice pattern 4 as shown in FIG. 3 is formed. be done.

If the incident angle of the ion beam 5 is smaller than the value of θ, the etched cross section will not have a sawtooth shape but will have a gouged shape.

By changing the type and energy of ions, RP, Δ
Since the value of X changes, it is easy to control the etched cross section.

In the above embodiment, the SiO□ substrate 1 is irradiated with N''4 on-beam and etched with hydrochloric acid, but the substrate, ion species, and etching solution are not limited.

Further, although the above embodiments are shown in terms of lattice patterns, they can also be applied to other optical elements such as prisms and mirrors.

C Effects of the Invention] As explained above, the present invention has the advantage that θ is janθ=Rp/Δ
When the value is derived from By selectively etching and removing the ion beam irradiated area by wet etching, the processed shape can be defined with high precision by physical values such as the average value Rp of the range of the ion beam. It has the advantage of good controllability of shape processing and the ability to form fine patterns.

Furthermore, since no resist is used, there is an effect that the in-plane uniformity of the processed shape is improved.

[Brief explanation of the drawing]

Figure 1 is a distribution diagram showing the lattice defect distribution that occurs in a substrate when a focused ion beam is irradiated from a direction perpendicular to the substrate.
Figure 2 is a distribution diagram showing the lattice defect distribution generated in the substrate when the focused ion beam is irradiated from a direction tilted by θ to the substrate, and Figure 3 is a distribution diagram showing the lattice defect distribution generated in the substrate by wet etching the sample shown in Figure 2. A pattern diagram showing the formed lattice pattern, and FIG. 4 is a cross-sectional view for explaining a conventional method of manufacturing a lattice pattern.

Claims (1)

[Claims] The average value of the range of the ion beam in the substrate is R_p, the average value of the lateral spread is ΔX, and θ is tan.
When the value is derived from θ=R_p/ΔX, a focused ion beam is irradiated from a direction tilted by an angle greater than θ with respect to the direction perpendicular to the substrate, and the ion beam is selectively irradiated into the substrate only in the ion beam irradiation area. causing lattice defects,
A method for manufacturing a lattice pattern, characterized in that the ion beam irradiation area is selectively etched away by wet etching.