JPH05150109A - Production of laminar type diffraction grating - Google Patents
Production of laminar type diffraction gratingInfo
- Publication number
- JPH05150109A JPH05150109A JP34013391A JP34013391A JPH05150109A JP H05150109 A JPH05150109 A JP H05150109A JP 34013391 A JP34013391 A JP 34013391A JP 34013391 A JP34013391 A JP 34013391A JP H05150109 A JPH05150109 A JP H05150109A
- Authority
- JP
- Japan
- Prior art keywords
- grating
- etching
- ion beam
- diffraction grating
- mixing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は格子溝の上面と底面が平
面である回折格子（ラミナー型回折格子）をイオンビー
ムエッチング法で作成する場合のエッチング方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching method for forming a diffraction grating (laminar type diffraction grating) having a grating groove having a flat top surface and a flat bottom surface by an ion beam etching method.
【０００２】[0002]
【従来の技術】回折格子をエッチング法によって作成す
るには、格子素材の上にレジスト層による格子パターン
のマスクを形成し、格子素材のマスクから露出している
部分をイオンビームエッチングで除去して行くことによ
り格子溝を形成する。従来このイオンビームエッチング
には反応性ガスを用いた反応性イオンビームエッチング
法が用いられている。格子パターンのマスクで格子素材
を覆ってイオンビームエッチングを行う場合、マスク自
体もエッチングを受けるから、格子素材に対してマスク
の方がエッチングされ難い、即ちエッチングレートが小
さいエッチング方法を選択する必要がある。このような
エッチング方法として格子素材にＳｉ系の無機質例えば
石英とかガラス等のＳｉＯ2 を主成分とする物質或はＳ
ｉ純品を用い、エッチングガスとして炭化水素のフッ化
物例えばＣＨＦ3 とかＣＦ4 等をエッチングガスとして
用いる反応性イオンビームエッチングが用いられてい
る。2. Description of the Related Art In order to form a diffraction grating by an etching method, a mask having a grating pattern of a resist layer is formed on the grating material, and the exposed portion of the mask of the grating material is removed by ion beam etching. A lattice groove is formed by going. Conventionally, a reactive ion beam etching method using a reactive gas has been used for this ion beam etching. When ion beam etching is performed by covering the lattice material with a mask having a lattice pattern, the mask itself is also etched, so it is difficult to etch the mask with respect to the lattice material, that is, it is necessary to select an etching method with a small etching rate. is there. As such an etching method, the lattice material is made of a Si-based inorganic material such as quartz or glass, which is a substance mainly composed of SiO 2 or S.
Reactive ion beam etching using a pure i product and a hydrocarbon fluoride such as CHF 3 or CF 4 as an etching gas is used as an etching gas.
【０００３】ラミナー型回折格子は格子を構成する突条
の上面と格子溝底が夫々水平面になっており、突条の両
側面即ち格子溝の両岸が垂直になっていることが望まし
いが、このような溝形をイオンビームエッチングで作る
場合、レジスト層に対する格子素材のエッチングレート
が充分大きい必要がある。即ちレジストによる格子パタ
ーンはレジストとしてフォトレジストを用い、ホログラ
フィック露光法により格子パターンを焼付ける場合、レ
ジストのマスクの断面は山形になっており、レジストは
エッチングの進行につれて山の高さが低くなると共に両
側縁が消失してマスクの格子条の幅が次第にせまくなっ
て行く。このため格子素材の露出部の幅が広がって、格
子溝の両側は傾斜面となる。ＣＨＦ3 とかＣＦ4 を用い
た反応性イオンビームエッチング法はレジストに対する
格子素材のエッチングレートを大きくできるが、それで
もラミナー型回折格子を作る場合、格子溝の両岸の垂直
度を満足な程度にすることは困難であった。またこれら
の反応性ガスを用いた反応性イオンビームエッチング法
では炭素が析出したり、チャンバー内の不純物がスパッ
タされて溝底に付着するため、格子溝の溝底が粗面とな
り、回折格子を真空紫外域で使う場合、この粗面による
光の散乱が大きくて、迷光レベルが高まり、回折格子と
しての性能が不十分であった。In the laminar type diffraction grating, it is desirable that the upper surface of the ridges and the bottom of the groove of the grating are horizontal planes, and both side surfaces of the ridge, that is, both sides of the grating groove are vertical. When forming such a groove shape by ion beam etching, the etching rate of the lattice material with respect to the resist layer must be sufficiently high. That is, when the grating pattern by resist uses photoresist as a resist and the grating pattern is baked by the holographic exposure method, the cross section of the resist mask has a mountain shape, and the height of the mountain of the resist decreases as the etching progresses. At the same time, the edges of both sides disappear and the width of the grid lines of the mask gradually becomes smaller. For this reason, the width of the exposed portion of the lattice material widens, and the both sides of the lattice groove become inclined surfaces. The reactive ion beam etching method using CHF 3 or CF 4 can increase the etching rate of the grating material with respect to the resist, but when making a laminar type diffraction grating, the perpendicularity of both sides of the grating groove can be made to a satisfactory degree. It was difficult. Further, in the reactive ion beam etching method using these reactive gases, carbon is deposited or impurities in the chamber are sputtered and adhere to the groove bottom, so that the groove bottom of the grating groove becomes a rough surface and the diffraction grating When used in the vacuum ultraviolet region, the scattering of light by this rough surface was large and the stray light level increased, resulting in insufficient performance as a diffraction grating.
【０００４】[0004]
【発明が解決しようとする課題】本発明は反応性イオン
ビームエッチングによるラミナー型回折格子の製作にお
いて、格子溝の両岸の垂直性を高め、溝底の荒れをなく
して平滑な溝底が得られるエッチング方法を得ようとす
るものである。DISCLOSURE OF THE INVENTION According to the present invention, in the production of a laminar type diffraction grating by reactive ion beam etching, the verticality of both sides of the grating groove is enhanced to prevent the groove bottom from becoming rough and to obtain a smooth groove bottom. It is intended to obtain an etching method that can be used.
【０００５】[0005]
【課題を解決するための手段】格子素材にＳｉＯ2 系無
機質材料を用い、反応性イオンビームエッチングの反応
ガスにＣＨＦ3 或はＣＦ4 等の炭化水素フッ化物を用
い、同ガスにＡｒを混合してイオンビームエッチングを
行うようにした。Means for Solving the Problems A SiO 2 inorganic material is used as a lattice material, a hydrocarbon fluoride such as CHF 3 or CF 4 is used as a reaction gas for reactive ion beam etching, and Ar is mixed with the gas. Then, ion beam etching was performed.
【０００６】[0006]
【作用】炭化水素フッ化物を反応性イオンビームエッチ
ングの反応性ガスとして用いると、ＳｉＯ2 系無機質材
料のレジスト層に対するエッチングレート比は比較的高
くなるが、これにＡｒを混合することにより、レジスト
のエッチングレートが減少し、エッチングレート比を更
に高めることができる。またＡｒの混入は炭化水素フッ
化物単独の場合において生じる析出炭素を除去するので
炭化水素フッ化物単独の場合に比しエッチング面の荒れ
が少なく、平滑な、溝底面が得られる。When a hydrocarbon fluoride is used as a reactive gas for reactive ion beam etching, the etching rate ratio of the SiO 2 based inorganic material to the resist layer is relatively high. The etching rate is reduced, and the etching rate ratio can be further increased. In addition, since Ar is mixed in to remove the precipitated carbon generated in the case of using only the hydrocarbon fluoride, the roughness of the etching surface is less than that in the case of using only the hydrocarbon fluoride, and a smooth groove bottom surface can be obtained.
【０００７】[0007]
【実施例】図１はＡ，Ｂ，Ｃ…の順に本発明方法の工程
の進行を示す。図で１は石英ガラスの格子素材で、図１
Ａに示すようにこの上にフォトレジストＯＦＰＲ５００
０の層２を０．４μｍの厚さに形成する。その後図１Ｂ
に示すようにＨｅ−Ｃｄレーザによる４４１．６ｎｍの
波長の光の２光束干渉による干渉縞をフォトレジスト層
２に投射露光して現像することにより、フォトレジスト
２による格子パタークのマスクを形成する。フォトレジ
ストに感光した干渉縞は現像により断面正弦波状にな
り、現像時間の調節で、格子素材１表面に断面正弦半波
状にフォトレジストを残す。その後反応性イオンビーム
エッチングを行うが、このとき、イオンビーム照射方向
は格子素材１の表面に対して垂直とし、反応性ガスとし
てＣＦ4を用い、Ａｒとの混合比を５０％対５０％とし
た。このエッチングにより格子溝が形成されて行き、溝
の深さは面積当たりのイオンビーム電流を一定に保ち、
エッチング時間で制御する。このようにして図１Ｃに示
すように格子溝が形成される。この過程でフォトレジス
ト２のエッチングの進行は格子素材のＳｉＯ2 に比し著
しく遅いので、フォトレジストのマスクの幅は殆ど減少
せず、溝の両岸は略垂直である。溝が所定の深さに達し
た時、エッチングを止め、残ったフォトレジスト２はＯ
2 のプラズマエッチングにより灰化除去し、その後図１
Ｅのように表面にＡｕ層３をコートして溝本数１２００
本／ｍｍのラミナー型回折格子が完成される。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the progress of the steps of the method of the present invention in the order of A, B, C ... In the figure, reference numeral 1 is a quartz glass lattice material.
As shown in A, a photoresist OFPR500 is formed on this.
0 layer 2 is formed to a thickness of 0.4 μm. Then Figure 1B
As shown in FIG. 3, an interference fringe due to two-beam interference of light having a wavelength of 441.6 nm by a He—Cd laser is projected and exposed on the photoresist layer 2 and developed to form a mask of a lattice pattern by the photoresist 2. The interference fringes exposed to the photoresist have a sinusoidal cross section by development, and the photoresist is left on the surface of the grating material 1 in a sinusoidal cross section by adjusting the development time. After that, reactive ion beam etching is performed. At this time, the ion beam irradiation direction is perpendicular to the surface of the lattice material 1, CF 4 is used as the reactive gas, and the mixing ratio with Ar is 50% to 50%. did. A lattice groove is formed by this etching, and the depth of the groove keeps the ion beam current per area constant,
Controlled by etching time. In this way, the lattice grooves are formed as shown in FIG. 1C. In this process, the progress of etching of the photoresist 2 is remarkably slower than that of SiO 2 which is a lattice material, so that the width of the photoresist mask is hardly reduced and both sides of the groove are substantially vertical. When the groove reaches a predetermined depth, the etching is stopped and the remaining photoresist 2 is O
Removed by ashing by plasma etching of 2 and then Fig. 1
As in E, the surface is coated with Au layer 3 and the number of grooves is 1200
A laminar type diffraction grating of book / mm is completed.
【０００８】上述実施例は反応性ガスとしてＣＦ4 を用
い、Ａｒの混合比５０％としたが、別実施例は反応性ガ
スとしてＣＨＦ3 を用い、ＣＨＦ3 ７０％、Ａｒ３０％
の混合ガスで反応性イオンビームエッチングを行い、そ
の他の工程は前例と同じにして、前例と同様の回折格子
を得た。格子基板は石英ガラスでなく普通ガラスでもよ
い。In the above embodiment, CF 4 was used as the reactive gas and the mixing ratio of Ar was 50%. In another embodiment, CHF 3 is used as the reactive gas, CHF 3 70% and Ar 30%.
Reactive ion beam etching was carried out with the mixed gas of, and the other steps were performed in the same manner as in the previous example to obtain a diffraction grating similar to the previous example. The lattice substrate may be ordinary glass instead of quartz glass.
【０００９】[0009]
【効果】炭化水素フッ化物を用いた反応性イオンビーム
エッチングにおいて、Ａｒを混合することによりレジス
トと格子素材とのエッチングレートが大きくなり、溝岸
が急峻な格子溝が得られ、Ａｒの清浄作用により炭素の
析出が防がれて溝底が平滑になるので、ラミナー型回折
格子の性能が向上する。またエッチング装置内面の析出
炭素もＡｒの清拭作用で除去されるので、エッチング装
置自体の手入れ頻度も減少される。[Effect] In reactive ion beam etching using a hydrocarbon fluoride, the mixing rate of Ar increases the etching rate of the resist and the lattice material, and a lattice groove with a steep ridge is obtained. As a result, the precipitation of carbon is prevented and the groove bottom becomes smooth, so that the performance of the laminar type diffraction grating is improved. Further, since the deposited carbon on the inner surface of the etching apparatus is also removed by the wiping action of Ar, the frequency of maintenance of the etching apparatus itself is reduced.
【図１】本発明の一実施例の工程の各段階を示す図。 １ 格子素材 ２ フォトレジスト ３ ＡｕコートFIG. 1 is a diagram showing each step of the process of one embodiment of the present invention. 1 Lattice material 2 Photoresist 3 Au coat
Claims (1)
質材料を用い、その上にフォトレジスト層による回折格
子パターンを形成して、炭化水素フッ化物にＡｒを混合
したガスを用いて格子素材面に垂直の方向からイオンビ
ームエッチングを行って格子溝を形成することを特徴と
するラミナー型回折格子製作法。1. A grating material is made of an inorganic material containing SiO 2 as a main component, a diffraction grating pattern is formed by a photoresist layer on the inorganic material, and the gas is a mixture of hydrocarbon fluoride and Ar. A laminar diffraction grating fabrication method characterized by forming a grating groove by performing ion beam etching from a direction perpendicular to the plane.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3340133A JP2737815B2 (en) | 1991-11-28 | 1991-11-28 | Laminar type diffraction grating fabrication method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3340133A JP2737815B2 (en) | 1991-11-28 | 1991-11-28 | Laminar type diffraction grating fabrication method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05150109A true JPH05150109A (en) | 1993-06-18 |
| JP2737815B2 JP2737815B2 (en) | 1998-04-08 |
Family
ID=18334043
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3340133A Expired - Lifetime JP2737815B2 (en) | 1991-11-28 | 1991-11-28 | Laminar type diffraction grating fabrication method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2737815B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9939577B2 (en) | 2016-04-20 | 2018-04-10 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Diffraction structure, diffraction grating, diffraction grating array, optical phased array, optical modulator, optical filter, laser source |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02244002A (en) * | 1989-03-17 | 1990-09-28 | Sekinosu Kk | Formation of optical diffraction grating core for injection molding |
| JPH03253802A (en) * | 1990-03-02 | 1991-11-12 | Hikari Keisoku Gijutsu Kaihatsu Kk | Fine working method |
-
1991
- 1991-11-28 JP JP3340133A patent/JP2737815B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02244002A (en) * | 1989-03-17 | 1990-09-28 | Sekinosu Kk | Formation of optical diffraction grating core for injection molding |
| JPH03253802A (en) * | 1990-03-02 | 1991-11-12 | Hikari Keisoku Gijutsu Kaihatsu Kk | Fine working method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9939577B2 (en) | 2016-04-20 | 2018-04-10 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Diffraction structure, diffraction grating, diffraction grating array, optical phased array, optical modulator, optical filter, laser source |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2737815B2 (en) | 1998-04-08 |
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