JP2005004068A - Method of forming slant rugged pattern and substrate having rugged pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dry etching method by which a slant rugged pattern is formed even on a substrate to be etched having a large area and to provide a substrate on which a slant irregular pattern is formed. <P>SOLUTION: A mask having an opening is provided on the substrate 11 and the substrate 11 is arranged in a slanted manner with respect to the etching direction of a dry etching device. Etching is conducted by relatively moving the substrate 11 with respect to the dry etching apparatus and scanning the surface of the substrate 11. It is desirable to use a RIBE dry etching apparatus 24 for this purpose. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a method for forming a slant uneven pattern that is obliquely etched with respect to a substrate, and a substrate on which a slant uneven pattern is formed. The present invention relates to a pattern forming method and a substrate on which a slant uneven pattern represented by the optical element is formed.
[0002]
[Prior art]
[0003]
[Patent Document 1] JP-A-10-96807 [Non-Patent Document 1] Applied Optics Vol. 36, no. 23, pp. 5717-5726
[Non-patent Document 2] Waveguide Grafting Couplers S. J. et al. Shear, Ming Li, Di Liao, Department of Engineering Science, Oxford University, Parks Road, Oxford OX1 3PJ United Kingdom / hx.
[0004]
A surface relief type diffraction grating (Non-Patent Document 1) or a holographic optical device provided with a slant uneven pattern having parallel groove walls and a plurality of grooves inclined obliquely with respect to the substrate surface. It is known as an element (Patent Document 1). The surface relief type diffraction grating of Non-Patent Document 1 has been shown to be useful as an input and output coupler in optical interconnection. Further, the holographic optical element of Patent Document 1 shows a diffraction grating that hardly generates 0th-order diffracted light, first-order diffracted light, and high-order diffracted light other than transmission, and has almost no wavelength dependency.
[0005]
As a method for forming a slant uneven pattern on a substrate, a metal thin film mask is provided on a photoresist formed by spin coating on a transparent substrate and placed on a table tilted at the same angle as the intended slant tilt. Then, it is fabricated by writing directly with ions by RIE (reactive ion etching) or RIBE (reactive ion beam etching) (Non-patent Document 1, Patent Document 1). As shown in FIG. 1, the transparent substrate thus dry-etched has slant irregularities having parallel groove walls and a plurality of grooves inclined obliquely with respect to the substrate surface etched in the direction of ions. A pattern is formed.
[0006]
However, when the substrate is disposed relatively obliquely with respect to the etching direction as in Non-Patent Document 1 or Patent Document 1, the ion generation chamber exit ( Since the distance between the electrode or the plasma outlet) and the substrate is greatly different, the processing characteristics are uneven because the radiation angle of the ion beam and the etching intensity are not uniform depending on the position of the substrate surface. For example, since the slant angle and depth of the obtained etched product are not uniform, there is a problem that the optical characteristics are uneven.
[0007]
From such a situation, in the conventional substrate on which the slant uneven pattern is formed, the range in which the substrate can be uniformly processed is limited to a minute region. For example, Non-Patent Document 1 merely forms a 2 mm square pattern.
[0008]
[Problems to be solved by the invention]
Therefore, the present invention relates to a method for forming a slant uneven pattern by a dry etching method, and a method for etching a substrate and a slant for forming a slant uneven pattern capable of forming a slant uneven pattern even on a substrate to be etched having a large area. It aims at providing the board | substrate which formed the uneven | corrugated pattern.
[0009]
[Means for Solving the Problems]
In the method for forming a slant uneven pattern of the present invention that solves the above-described problems, a mask having an opening is provided on a substrate, and the substrate surface is disposed obliquely with respect to the etching direction of the dry etching apparatus. Etching while relatively moving the substrate and scanning the substrate surface. The dry etching apparatus is preferably RIE or RIBE.
[0010]
In addition, the substrate having the slant uneven pattern of the present invention is a substrate formed by the method for forming a slant uneven pattern and formed with a plurality of grooves whose center lines are inclined with respect to the substrate surface. As shown in FIG. 1, the substrate obtained by the slant uneven pattern forming method of the present invention has a plurality of grooves 12 whose centerlines are inclined with respect to the surface of the transparent substrate 11 etched in the irradiation direction of ionizing radiation. A slant uneven pattern is formed. Examples of the cross-sectional shape of the groove 12 include parallelograms, trapezoids, triangles and the like whose centerlines are inclined.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be further described.
[0012]
The method for forming a slant uneven pattern according to the present invention will be described with reference to FIGS. FIG. 2 is a process diagram showing an example of a method for forming a slant uneven pattern according to the present invention. First, as shown in FIG. 2A, a transparent substrate 11 such as optically polished quartz glass is prepared, and a resist layer 13 that is hardened by ionizing radiation is coated on the surface, and ionized radiation irradiation apparatus is used for ionization. A predetermined pattern is drawn on the resist layer 13 by irradiating the radiation 14. Thereafter, the drawn resist layer 13 is developed to form a resist pattern 15 as shown in FIG. 2B on the surface of the transparent substrate 11.
[0013]
Next, as shown in FIG. 2C, the transparent substrate 11 on which the resist pattern 15 is formed is placed on the substrate table 16 inclined at the same angle as the inclination angle φ of the target groove 12, and RIBE dry etching is performed. The apparatus is irradiated with an ion beam 17 to generate plasma composed of a mixed gas of CF ₄ and O ₂ , and plasma etching is performed obliquely from above the surface of the transparent substrate 11. The RIBE dry etching apparatus, for example, as shown in FIG. 3, a plasma generation chamber 21, an etching chamber 22, and a substrate for placing a transparent substrate 11 disposed in the etching chamber 22 and inclined at a predetermined angle. A RIBE dry etching apparatus 24 that is a table and has a substrate table 23 movable in the substrate surface direction can be used.
[0014]
At this time, the ion exit (plasma exit) of the RIBE dry etching apparatus 24 and the transparent substrate 11 are relatively moved to scan the surface of the transparent substrate 11 in, for example, the direction indicated by the arrow on the substrate surface shown in FIG. Etching is performed by irradiating the beam 17 obliquely with respect to the substrate surface, and by controlling the etching time precisely, the etching depth d (FIG. 1) is controlled to a predetermined value, and there are parallel groove walls. In the direction of the ion beam 17, a slant uneven pattern having a plurality of repetitive grooves 12 inclined obliquely with respect to the surface of the transparent substrate 11 that has been accurately etched to a predetermined depth is formed into a uniform processing region 30 on the surface of the transparent substrate 11. (FIGS. 2D and 4). According to the present invention, the size of the uniform processing region 30 surrounded by the dotted line in FIG. 4 can be 50 mm square. Regarding the scan processing, it is necessary to determine the scan interval so that the scan range includes the region and unevenness does not occur due to the balance between the scan interval and the influence range of the ion beam 17.
[0015]
Note that an etching stopper layer 18 shown by a broken line in FIG. 2A may be provided in the transparent substrate 11 in advance, and the etching depth d may be set to a predetermined value, or both may be used in combination. Also good.
[0016]
Finally, the resist pattern 15 is removed by ashing or the like to obtain a substrate having a slant uneven pattern as shown in FIG.
[0017]
In the above description, the resist pattern 15 formed by photolithography is used as a mask for dry etching. First, a chromium layer is provided on the surface of the transparent substrate 11, and an ionizing radiation curable resist is provided thereon. The layer 13 is coated, the ionizing radiation curable resist layer 13 is patterned so as to correspond to the interference fringes of a predetermined hologram, and the chromium layer exposed from the opening of the resist pattern 15 is formed of CH ₂ Cl ₂ and O ₂ . Etching is performed with an etching gas composed of a mixed gas, and the transparent substrate 11 is etched using a mask composed of the resist pattern 15 and the underlying chromium pattern, or a mask composed only of the chromium pattern from which the resist pattern 15 has been removed. The same obliquely inclined groove 12 may be formed. Good. The dry etching is not limited to reactive ion etching or reactive ion beam etching, but may be other dry etching such as ion etching, ion beam etching, neutral beam etching, focal ion beam etching, and sputter etching.
[0018]
Alternatively, as shown in the process diagram for forming the slant uneven pattern of the present invention shown in FIG. 5, a photoresist layer 32 is first provided on the surface of the transparent substrate 31 by holographic exposure (FIG. 5 (a)), and then on it. A shadow coating is performed with aluminum (FIG. 5B), an aluminum layer 33 is formed, the remaining photoresist is removed by oxygen plasma etching (FIG. 5C), and aluminum is coated thereon (FIG. 5B). (D)) A mask 34 made of an aluminum layer is formed by raising the metal, and then an ion beam by RIBE is irradiated at an oblique angle (FIG. 5 (e)), and then the mask 34 is peeled off. A method of obtaining a substrate having a slant uneven pattern as shown in FIG.
[0019]
【The invention's effect】
According to the present invention, the etching direction of the dry etching apparatus is inclined with respect to the substrate surface, and the etching apparatus and the substrate are moved relatively to perform the etching while scanning the substrate surface. In forming the slant uneven pattern, a uniform processing region having a large area of several hundred times or more can be achieved as compared with the conventional method in which the relative position between the etching apparatus and the substrate is fixed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a slant uneven pattern having a plurality of grooves having parallel groove walls and inclined obliquely with respect to a substrate surface etched in the direction of an ion beam.
FIG. 2 is a process diagram showing an example of a method for forming a slant uneven pattern according to the present invention.
FIG. 3 is a view showing a RIBE dry etching apparatus having a plasma generation chamber and an etching chamber.
FIG. 4 is a diagram showing ion beam irradiation while scanning a substrate surface in a direction indicated by an arrow.
FIG. 5 is a process diagram of forming the slant uneven pattern of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Transparent substrate 12 Groove 13 Resist layer 14 Ionizing radiation 15 Resist pattern 16 Substrate stand 17 Ion beam 18 Etching stopper layer 21 Plasma generation chamber 22 Etch chamber 23 Substrate stand 24 RIBE dry etching apparatus 30 Uniform processing region 31 Transparent substrate 32 Photoresist layer 33 Aluminum layer 34 Mask

Claims (3)

A mask having an opening is provided on the substrate, the substrate surface is tilted with respect to the etching direction of the dry etching apparatus, and the dry etching apparatus and the substrate are moved relatively to perform etching while scanning the substrate surface. A method of forming a slant uneven pattern characterized by the above. The method for forming a slant uneven pattern according to claim 1, wherein the dry etching apparatus is RIE or RIBE. A substrate having a slant concavo-convex pattern formed by the method for forming a slant concavo-convex pattern according to claim 1 or 2 and formed with a plurality of grooves whose centerlines are inclined with respect to the substrate surface.

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