JP2001074931A - Optical thin film, optical element and optical device - Google Patents
Optical thin film, optical element and optical deviceInfo
- Publication number
- JP2001074931A JP2001074931A JP24633899A JP24633899A JP2001074931A JP 2001074931 A JP2001074931 A JP 2001074931A JP 24633899 A JP24633899 A JP 24633899A JP 24633899 A JP24633899 A JP 24633899A JP 2001074931 A JP2001074931 A JP 2001074931A
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- optical
- thin film
- optical thin
- oxide layer
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光学用の、特に波
長が１５０ｎｍ以上２００ｎｍ以下の紫外用、更に特に
同波長域のレーザ光で用いる光学薄膜及びこれを具えた
光学素子及びこれを組み込んだ光学装置に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical thin film for use in optics, particularly for ultraviolet light having a wavelength of 150 nm or more and 200 nm or less, and more particularly for use in laser light in the same wavelength range, and an optical element having the same and an optical element having the same. The present invention relates to an optical device.
【０００２】[0002]
【従来の技術】近年、半導体デバイスの集積度を増すた
めに、半導体デバイス製造プロセスのリソグラフィープ
ロセスで用いられる縮小投影露光装置（ステッパー）の
高解像度化の要求が高まっている。高解像度を達成する
ための一つの方法として光源波長の短波長化が挙げら
れ、そのために最近では、水銀ランプよりも短波長域の
光を発振でき、かつ高出力なエキシマレーザを光源とし
たステッパーの実用化が始まっている。それに伴って、
この短波長域において使用可能な光学素子の開発が重要
になってきている。2. Description of the Related Art In recent years, in order to increase the degree of integration of semiconductor devices, there is an increasing demand for higher resolution of a reduction projection exposure apparatus (stepper) used in a lithography process of a semiconductor device manufacturing process. One way to achieve high resolution is to shorten the wavelength of the light source, and recently a stepper that uses a high-power excimer laser as the light source can emit light in a shorter wavelength range than a mercury lamp. Practical use of has started. Along with that,
Development of an optical element that can be used in this short wavelength region has become important.
【０００３】この短波長域において使用される光学素子
は、短波長光を透過する光学基板上に通常、高反射膜ま
たは反射防止膜等の光学薄膜を具えており、この光学薄
膜は通常、複数の層から構成されている。この光学素子
が縮小投影露光装置等の光学系に組み込まれるのであ
る。An optical element used in the short wavelength region usually includes an optical thin film such as a high reflection film or an antireflection film on an optical substrate that transmits short wavelength light. It consists of layers. This optical element is incorporated in an optical system such as a reduction projection exposure apparatus.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら従来の光
学素子には光学素子へのレーザ照射によって光学素子表
面に形成された光学薄膜が破壊する問題、即ちレーザ耐
久性が低い問題があった。この破壊の程度は一般に照射
パワーが高く、且つ短波長になるほど甚だしい。光学薄
膜のレーザ耐久性は、光学薄膜及びこれを具えた光学素
子及びこの光学素子を組み込んだ光学装置の良好な光学
特性を安定的に維持するために極めて重要である。However, the conventional optical element has a problem that the optical thin film formed on the surface of the optical element is destroyed by laser irradiation on the optical element, that is, the laser durability is low. In general, the degree of this destruction becomes greater as the irradiation power becomes higher and the wavelength becomes shorter. The laser durability of the optical thin film is extremely important for stably maintaining good optical properties of the optical thin film, the optical element including the optical thin film, and the optical device incorporating the optical element.
【０００５】レーザによる光学薄膜の破壊メカニズムは
今だ充分には解明されていないが、光学薄膜物質の吸収
発熱による融解、熱応力による脆性破壊、強い光電界に
よる絶縁破壊などによるとするのが通説である。例え
ば、光学薄膜の光吸収や光学薄膜内部の電界強度分布や
光学基板加工後の表面の凹凸や光学基板表面の研磨材等
の残留物が光学薄膜の破壊の原因となるとするものであ
る。Although the mechanism of the destruction of an optical thin film by a laser has not yet been fully elucidated, it is generally accepted that melting of the optical thin film material due to absorption and heating, brittle destruction due to thermal stress, and dielectric breakdown due to a strong optical electric field are caused. It is. For example, light absorption of the optical thin film, electric field intensity distribution inside the optical thin film, surface irregularities after processing of the optical substrate, and residues such as abrasives on the surface of the optical substrate cause damage to the optical thin film.
【０００６】従来、紫外領域のレーザ光で使用される光
学素子用の光学薄膜では、光学基板上に１種類の物質ま
たは屈折率の異なる２種類以上の物質を単層または積層
して形成して、反射防止特性、または反射特性等の所望
の光学特性を達成するように設計製造されていた。そし
てレーザ耐久性を高めるためには、使用波長での光吸収
係数が小さい物質を積層物質として選定し、これらの物
質を最適に組み合わせる他に、各層の光学膜厚の最適
化、さらには形成された層物質の光吸収係数を極力小さ
くするための成膜方法の改良などが試みられてきた。Conventionally, in an optical thin film for an optical element used for laser light in the ultraviolet region, one kind of substance or two or more kinds of substances having different refractive indices are formed in a single layer or laminated on an optical substrate. It has been designed and manufactured to achieve desired optical characteristics such as anti-reflection characteristics or reflection characteristics. In order to increase the laser durability, a material having a small light absorption coefficient at the used wavelength is selected as the laminated material, and in addition to optimally combining these materials, the optical film thickness of each layer is optimized, and furthermore, it is formed. Attempts have been made to improve the film forming method for minimizing the light absorption coefficient of the layered material.
【０００７】このように、従来の光学薄膜のレーザ耐久
性向上の改良主眼はレーザ光の光吸収量をいかに小さく
するかということに置かれ、その研究成果から最終的な
光学素子を開発してきた。しかしながら、最近、以上の
ような観点だけからは更にレーザ耐久性の高い光学薄膜
を得ることができないことが徐々に判明してきた。この
ことは使用する波長の短波長化、高照射パワー化に伴っ
てますます顕在化し、より一層レーザ耐久性向上を図る
ためにはこの問題を解決する必要が高まってきた。[0007] As described above, the main focus of the improvement of the laser durability of the conventional optical thin film has been on how to reduce the light absorption amount of the laser light, and the final optical element has been developed from the research results. . However, recently, it has gradually been found that it is not possible to obtain an optical thin film having even higher laser durability from the above viewpoint alone. This becomes more and more conspicuous as the wavelength used becomes shorter and the irradiation power becomes higher, and it is necessary to solve this problem in order to further improve the laser durability.
【０００８】本発明はこれらの問題を解決し、よりレー
ザ耐久性の高い光学薄膜、及び光学素子、及び光学装置
を提供することを目的とする。An object of the present invention is to solve these problems and to provide an optical thin film, an optical element, and an optical device having higher laser durability.
【０００９】[0009]
【課題を解決するための手段】上記問題点を解決するた
めに、本発明は第一に、光学基板上に密度が２．６ｇ／
ｃｍ3 以上の１層以上の酸化アルミニウム層と１層以上
の酸化ケイ素層とを積層状に具えることを特徴とする光
学薄膜（請求項１）を提供する。また、本発明は第二
に、前記酸化ケイ素層の密度が１．６ｇ／ｃｍ3 以上で
あることを特徴とする請求項１記載の光学薄膜（請求項
２）を提供する。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention firstly provides an optical substrate having a density of 2.6 g / g.
An optical thin film (Claim 1) characterized in that it comprises at least one aluminum oxide layer and at least one silicon oxide layer having a thickness of at least 3 cm 3 and at least one silicon oxide layer. Secondly, the present invention provides the optical thin film according to claim 1, wherein the silicon oxide layer has a density of 1.6 g / cm 3 or more.
【００１０】また、本発明は第三に、前記光学薄膜の最
表面層の表面粗さがｒｍｓ値で１０Å以下であることを
特徴とする請求項１〜２何れか１項記載の光学薄膜（請
求項３）を提供する。また、本発明は第四に、波長が１
５０ｎｍ以上２００ｎｍ以下の紫外光で用いられること
を特徴とする請求項１〜３何れか１項記載の光学薄膜
（請求項４）を提供する。[0010] Thirdly, in the present invention, the surface roughness of the outermost surface layer of the optical thin film is 10 ° or less in rms value. Claim 3) is provided. Fourth, the present invention has a wavelength of 1
The optical thin film according to any one of claims 1 to 3, which is used for ultraviolet light having a wavelength of 50 nm or more and 200 nm or less (claim 4).
【００１１】また、本発明は第五に、前記酸化アルミニ
ウム層と酸化ケイ素層の片方または両方がスパッタ法に
て成膜されることを特徴とする請求項１〜４何れか１項
記載の光学薄膜（請求項５）を提供する。また、本発明
は第六に、前記酸化アルミニウム層と酸化ケイ素層の片
方または両方がイオンプレーティング法にて成膜される
ことを特徴とする請求項１〜４何れか１項記載の光学薄
膜（請求項６）を提供する。Fifthly, in the present invention, one or both of the aluminum oxide layer and the silicon oxide layer are formed by a sputtering method. A thin film (claim 5) is provided. In the sixth aspect of the present invention, the optical thin film according to any one of claims 1 to 4, wherein one or both of the aluminum oxide layer and the silicon oxide layer are formed by an ion plating method. (Claim 6) is provided.
【００１２】また、本発明は第七に、前記酸化アルミニ
ウム層と酸化ケイ素層の片方または両方がイオンビーム
アシスト蒸着法にて成膜されることを特徴とする請求項
１〜４何れか１項記載の光学薄膜（請求項７）を提供す
る。また、本発明は第八に、光学基板と請求項１〜７何
れか１項記載の光学薄膜とを具えた光学素子（請求項
８）を提供する。In the present invention, seventhly, one or both of the aluminum oxide layer and the silicon oxide layer are formed by an ion beam assisted vapor deposition method. An optical thin film as defined in claim 7 is provided. Eighth, the present invention provides an optical element (claim 8) including an optical substrate and the optical thin film according to any one of claims 1 to 7.
【００１３】また、本発明は第九に、請求項８記載の光
学素子が組み込まれ、レーザ耐久性が向上された光学装
置（請求項９）を提供する。Ninthly, the present invention provides an optical device incorporating the optical element according to claim 8 and having improved laser durability (claim 9).
【００１４】[0014]
【発明の実施の形態】本発明の実施の形態の光学薄膜
は、高屈折率層である酸化アルミニウム層２と低屈折率
層である酸化ケイ素層３とから構成されている。ここで
高屈折率層とは、基板よりも高い屈折率の層のことを、
低屈折率層とは、基板よりも低い屈折率の層のことを意
味する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical thin film according to an embodiment of the present invention comprises an aluminum oxide layer 2 as a high refractive index layer and a silicon oxide layer 3 as a low refractive index layer. Here, the high refractive index layer is a layer having a higher refractive index than the substrate,
The low refractive index layer means a layer having a lower refractive index than the substrate.
【００１５】光学基板としては、石英硝子や蛍石等など
が好ましく用いられ、１５０〜２００ｎｍの波長範囲で
透明に調整された基板が特に好ましく用いられる。この
光学薄膜の構成膜は高密度化されている。酸化アルミニ
ウム層は所定値以上に高密度化され、更に必要に応じ
て、酸化ケイ素層も所定値以上に高密度化されている。As the optical substrate, quartz glass, fluorite or the like is preferably used, and a substrate adjusted to be transparent in a wavelength range of 150 to 200 nm is particularly preferably used. The constituent films of this optical thin film are densified. The density of the aluminum oxide layer is higher than a predetermined value, and the density of the silicon oxide layer is higher than a predetermined value, if necessary.
【００１６】この密度の下限は、レーザ光による光学素
子の破壊メカニズムの詳細な研究の結果見つけられた。
高反射膜のレーザ耐久性の向上のために、膜物性として
光吸収係数の低減以外に、膜の密度を上記値以上に高め
ることが有効なのである。レーザ耐久性を向上させるた
めには、光吸収が酸化ケイ素層よりも比較的大きく、レ
ーザ耐久性を支配していると考えられる酸化アルミニウ
ム層の密度を２．６ｇ／cm3以上に、より好ましくは
２．８ｇ／cm3以上に調整することが好ましい。更に、
酸化アルミニウム層の高密度化と併せて酸化ケイ素層の
密度を１．６ｇ／cm3以上に調整することが最も好まし
い。The lower limit of the density was found as a result of a detailed study of the mechanism of destruction of an optical element by laser light.
In order to improve the laser durability of the high-reflection film, it is effective to increase the density of the film beyond the above value in addition to reducing the light absorption coefficient as the physical properties of the film. In order to improve laser durability, the density of the aluminum oxide layer, which is relatively large in light absorption than the silicon oxide layer and is considered to govern laser durability, is more preferably at least 2.6 g / cm 3. Is preferably adjusted to 2.8 g / cm 3 or more. Furthermore,
Most preferably, the density of the silicon oxide layer is adjusted to 1.6 g / cm 3 or more in conjunction with increasing the density of the aluminum oxide layer.
【００１７】また、構成層の高密度化と併せて、光学薄
膜の表面粗さを１０Åｒｍｓ（ｒｏｏｔ ｍｅａｎ ｓ
ｑｕａｒｅで１０Å）以下、より好ましくは５Åｒｍｓ
以下にすることが好ましい。光学薄膜の成膜法としては
真空蒸着法、スパッタ法（ＲＦスパッタ法、イオンビー
ムスパッタ法、等）、イオンプレーティング法、イオン
ビームアシスト蒸着法、等があり、特には限定されない
が、スパッタ法又はイオンプレーティング法又はイオン
ビームアシスト蒸着法が密度を高くすることが容易であ
るために好ましい方法である。In addition to increasing the density of the constituent layers, the surface roughness of the optical thin film is reduced to 10 ° rms (root mean s).
less than 10 °), more preferably 5 ° rms
It is preferable to set the following. Examples of the method for forming an optical thin film include a vacuum deposition method, a sputtering method (RF sputtering method, ion beam sputtering method, etc.), an ion plating method, an ion beam assisted deposition method, and the like. Alternatively, an ion plating method or an ion beam assisted evaporation method is a preferable method because it is easy to increase the density.
【００１８】この光学薄膜としては、高反射膜、反射防
止膜、ビームスプリッター、エッジフィルター、等あら
ゆる種類の光学薄膜が対象であり、使用波長、必要な光
学特性仕様に対して最適化するよう、各膜構成、各構成
膜の層数、及び各膜厚が調整されている。本発明の光学
薄膜、更にこれを具えた光学素子、この光学素子を組み
込んだ光学装置、特に縮小投影露光装置は、１５０〜２
００ｎｍの紫外域で好ましく用いられる。特にエキシマ
レーザ光、ハロゲン分子レーザ光、高調波レーザ光で好
ましく用いられ、レーザ耐久性が高いため、長期に渡っ
て良好な光学特性を維持できる。 ［実施例］図１に本実施例の光学薄膜として紫外域レー
ザ用高反射膜の断面図が示されている。この高反射膜
は、光学基板（石英硝子）１上に、設計中心波長λを１
９３ｎｍとしたとき、光学的膜厚０．２５λの高屈折率
層である酸化アルミニウム層２と光学的膜厚０．２５λ
の低屈折率層である酸化ケイ素層３とからなる交互層を
約３５層成膜し、その上に最上層として光学的膜厚０．
５０λの酸化ケイ素層を成膜することにより構成されて
いる。The optical thin film includes all kinds of optical thin films such as a high reflection film, an anti-reflection film, a beam splitter, an edge filter, and the like. Each film configuration, the number of layers of each constituent film, and each film thickness are adjusted. The optical thin film of the present invention, the optical element having the same, and the optical device incorporating the optical element, particularly the reduction projection exposure apparatus, are 150 to 2
It is preferably used in the ultraviolet region of 00 nm. In particular, it is preferably used for excimer laser light, halogen molecule laser light, and harmonic laser light, and has high laser durability, so that good optical characteristics can be maintained for a long period of time. [Embodiment] FIG. 1 is a sectional view of a high-reflection film for an ultraviolet laser as an optical thin film of this embodiment. This high-reflection film has a design center wavelength λ of 1 on an optical substrate (quartz glass) 1.
When the thickness is 93 nm, an aluminum oxide layer 2 which is a high refractive index layer having an optical thickness of 0.25λ and an optical thickness of 0.25λ
About 35 alternate layers composed of the silicon oxide layer 3 as a low refractive index layer are formed, and an optical layer having an optical thickness of 0.1 is formed thereon as the uppermost layer.
It is formed by forming a 50 λ silicon oxide layer.
【００１９】図２のサンプルＡは、イオンビームスパッ
タ法にて、ターゲット材料として酸化アルミニウムと酸
化ケイ素を、スパッタガスにはＡｒガスを用い、酸素ガ
スを１〜５ｍｌ／ｍｉｎで調整しながら、１ｋＶのスパ
ッタ電圧で成膜した。サンプルＢは、ＲＦスパッタ法に
て、ターゲット材料として各金属物質を、スパッタガス
にはＡｒガスを用い、酸素流量を０〜３ｍｌ／ｍｉｎで
調整しながら、投入電力０．２〜０．８ｋＷにて成膜し
た。The sample A of FIG. 2 was prepared by ion beam sputtering using aluminum oxide and silicon oxide as target materials, Ar gas as a sputtering gas, and adjusting the oxygen gas at 1 to 5 ml / min. At a sputtering voltage of Sample B was prepared by RF sputtering, using each metal substance as a target material and using Ar gas as a sputtering gas, while adjusting the oxygen flow rate at 0 to 3 ml / min to a power of 0.2 to 0.8 kW. To form a film.
【００２０】サンプルＣ、Ｄは、蒸着物質として酸化ア
ルミニウムと酸化ケイ素を用い、酸素ガス雰囲気中にて
電子ビーム加熱により成膜した。サンプルＣ、Ｄ間では
圧力条件が異なっている。表１に各種条件により成膜し
た高反射膜の構成膜の物性を示す。Samples C and D were formed by electron beam heating in an oxygen gas atmosphere using aluminum oxide and silicon oxide as evaporation materials. The pressure conditions are different between samples C and D. Table 1 shows the physical properties of the constituent films of the high reflection film formed under various conditions.
【００２１】[0021]
【表１】 [Table 1]
【００２２】ここで、密度はラザフォード後方散乱（Ｒ
ＢＳ）測定により求めた。ラザフォード後方散乱（ＲＢ
Ｓ）測定法は、数百万電子ボルトに加速された荷電粒子
を用いて薄膜の組成を非破壊的に、短時間にしかも高精
度で測定する方法である。加速されたイオンを光学薄膜
サンプルに入射したときに得られる後方散乱イオンのエ
ネルギースペクトルの解析を行なうことによって薄膜サ
ンプルの付着量を求める。この付着量と、別に光学的測
定法、等で測定された膜厚とから、膜密度を算出するこ
とができる。ラザフォード後方散乱（ＲＢＳ）測定法
は、光・薄膜技術マニュアル（オプトロニクス社）に紹
介されている。Where the density is Rutherford backscattering (R
BS). Rutherford Backscatter (RB
S) The measuring method is a method for non-destructively measuring the composition of a thin film using charged particles accelerated to several million electron volts in a short time and with high accuracy. The amount of adhered thin film sample is determined by analyzing the energy spectrum of backscattered ions obtained when the accelerated ions are incident on the optical thin film sample. The film density can be calculated from the amount of adhesion and the film thickness separately measured by an optical measurement method or the like. Rutherford backscattering (RBS) measurement methods are introduced in the Optical and Thin Film Technical Manual (Optronics).
【００２３】図２にて、Ａ、Ｂ、Ｃが本実施例の高反射
膜であり、サンプルＤが従来例の高反射膜である。これ
らの各高反射膜に対するレーザ耐久性を、レーザーイン
デュースドダメージスレッショールド（ｌａｓｅｒ ｉ
ｎｄｕｃｅｄ ｄａｍａｇｅｔｈｒｅｓｈｏｌｄ：ＬＩ
ＤＴと略記する）測定法にて評価した結果を図２に示
す。ＬＩＤＴ測定法は、測定するサンプルの表面に照射
エネルギー密度を変化させたレーザ光を場所を変えなが
ら照射し、破壊の有無を顕微鏡にて観察して膜の破壊の
如何を判定する方法である。図２に於いて、横軸はパル
ス発振レーザ光の照射パルス数、縦軸はレーザ光の照射
エネルギー密度、即ちフルーエンスであり、各座標点は
各サンプル毎に照射パルス数と膜の破壊有り無しの閾値
となるフルーエンスとを示す。In FIG. 2, A, B, and C are high-reflection films of the present embodiment, and sample D is a high-reflection film of a conventional example. The laser durability for each of these high-reflection films is determined by the laser induced damage threshold (laser i).
nduced damage threshold: LI
The results evaluated by the measurement method (abbreviated as DT) are shown in FIG. The LIDT measurement method is a method of irradiating the surface of a sample to be measured with a laser beam having a changed irradiation energy density while changing its location, and observing the presence or absence of breakage with a microscope to determine whether the film is broken. In FIG. 2, the horizontal axis is the number of irradiation pulses of the pulsed laser light, the vertical axis is the irradiation energy density of the laser light, that is, fluence, and each coordinate point is the number of irradiation pulses and whether or not the film is broken for each sample. Fluence, which is the threshold value of
【００２４】光源はＡｒＦエキシマレーザであり、発振
波長は１９３ｎｍ、パルス半値幅は約２０ｎｓ、ランダ
ム偏光である。照射周波数は１〜１００Ｈｚまで可変し
て行なった。図２よりサンプルＡ、Ｂは照射パルス数を
増やしても照射エネルギー密度の低下が小さいのに対し
て、サンプルＣは若干の低下が、サンプルＤではエネル
ギー密度の大きな低下が見られる。我々は、この照射パ
ルス数を増やしても照射エネルギー密度の低下が少ない
サンプルをレーザ耐久性が高いサンプルと呼んでいる。
この評価結果と表１の密度の比較により、高反射膜の密
度を高めることでレーザ耐久性を向上させることが可能
であることが分かった。密度が高い高反射膜のレーザ耐
久性が向上するメカニズムについては今のところ未解明
であるが、密度を高めることで膜内部における粒界が減
少し、粒界における散乱回折等による電界強度の集中が
緩和されることが関係しているのではないかと推定して
いる。The light source is an ArF excimer laser, the oscillation wavelength is 193 nm, the pulse half width is about 20 ns, and the light is randomly polarized. The irradiation frequency was varied from 1 to 100 Hz. As shown in FIG. 2, the decrease in the irradiation energy density is small for the samples A and B even when the number of irradiation pulses is increased, while the sample C shows a slight decrease and the sample D shows a large decrease in the energy density. We call a sample with a small decrease in irradiation energy density even if the number of irradiation pulses is increased a sample with high laser durability.
By comparing the evaluation results with the densities in Table 1, it was found that the laser durability can be improved by increasing the density of the high reflection film. The mechanism by which the laser durability of a high-density high-reflection film is improved is not known at this time, but increasing the density reduces the grain boundaries inside the film, and the concentration of the electric field intensity due to scattering diffraction at the grain boundaries. It is presumed that this may be related to mitigation.
【００２５】更に表１のサンプルの表面粗さに着目する
と、図２に於いて、例えば、表面粗さ１２Åｒｍｓのサ
ンプルＤのレーザ耐久性が低く、表面粗さ２Åｒｍｓの
サンプルＡのレーザ耐久性が高いように、表面粗さが小
さいほどレーザ耐久性が向上している。これの理由も詳
細はまだ不明であるが、表面粗さを小さくすることで膜
の凹凸における散乱回折等による電界強度の乱れや集中
が緩和されることが関係しているのではないかと推定し
ている。Further focusing on the surface roughness of the samples shown in Table 1, in FIG. 2, for example, the laser durability of sample D having a surface roughness of 12 Årms is low, and the laser durability of sample A having a surface roughness of 2 Årms is low. As shown, the smaller the surface roughness, the higher the laser durability. The reason for this is still unknown, but it is presumed that reducing the surface roughness may be related to reducing the disturbance and concentration of the electric field intensity due to scattering diffraction etc. on the unevenness of the film. ing.
【００２６】[0026]
【発明の効果】以上説明した通り、本発明にかかる光学
薄膜は、請求項１、２、４、５、６、７の発明によると
構成膜が高密度であるために紫外域特に１５０〜２００
ｎｍの波長域でレーザ耐久性が高い。請求項３、４、
５、６、７の発明によると高密度と併せて表面粗さが小
さいので、更に一層レーザ耐久性が高い。そのためこの
光学薄膜を具えた光学素子の、更にはこの光学素子を組
み込んだ光学装置、特には紫外域のレーザ光で用いる縮
小投影露光装置のレーザ耐久性は向上され、長期に渡っ
て良好な光学特性を維持することが出来る。As described above, according to the first, second, fourth, fifth, sixth and seventh aspects of the present invention, the optical thin film according to the present invention has a high density in the ultraviolet region, particularly in the range of 150 to 200, because of its high density.
High laser durability in the wavelength region of nm. Claims 3, 4,
According to the inventions of 5, 6, and 7, since the surface roughness is small in addition to the high density, the laser durability is further enhanced. Therefore, the laser durability of the optical element provided with the optical thin film, and further, of the optical device incorporating the optical element, particularly the reduction projection exposure apparatus used with ultraviolet laser light, has been improved, and a good optical property has been obtained over a long period of time. Characteristics can be maintained.
【図１】本発明の一実施例である紫外域レーザ用高反射
膜の断面図である。FIG. 1 is a sectional view of a high-reflection film for an ultraviolet laser according to an embodiment of the present invention.
【図２】本発明の一実施例である紫外域レーザ用高反射
膜のＬＩＤＴ測定結果である。FIG. 2 is a LIDT measurement result of a high-reflection film for an ultraviolet laser according to an embodiment of the present invention.
１ 光学基板（石英硝子） ２ 酸化アルミニウム層 ３ 酸化ケイ素層 ４ 最上層酸化ケイ素層 Reference Signs List 1 optical substrate (quartz glass) 2 aluminum oxide layer 3 silicon oxide layer 4 uppermost silicon oxide layer
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｃ２３Ｃ 14/10 Ｃ２３Ｃ 14/10 14/32 14/32 Ｚ 14/48 14/48 Ｄ Ｇ０２Ｂ 5/28 Ｇ０２Ｂ 5/28 ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 7 Identification symbol FI Theme coat ゛ (Reference) C23C 14/10 C23C 14/10 14/32 14/32 Z 14/48 14/48 D G02B 5/28 G02B 5/28
Claims (9)
の１層以上の酸化アルミニウム層と１層以上の酸化ケイ
素層とを積層状に具えることを特徴とする光学薄膜。1. An optical thin film comprising an optical substrate and one or more aluminum oxide layers having a density of 2.6 g / cm 3 or more and one or more silicon oxide layers laminated thereon.
3 以上であることを特徴とする請求項１記載の光学薄
膜。2. The silicon oxide layer has a density of 1.6 g / cm.
The optical thin film according to claim 1, wherein the number is 3 or more.
ｓ値で１０Å以下であることを特徴とする請求項１〜２
何れか１項記載の光学薄膜。3. The surface roughness of the outermost layer of the optical thin film is rm.
3. The s value is not more than 10 [deg.].
The optical thin film according to claim 1.
外光で用いられることを特徴とする請求項１〜３何れか
１項記載の光学薄膜。4. The optical thin film according to claim 1, wherein the optical thin film is used for ultraviolet light having a wavelength of 150 nm or more and 200 nm or less.
片方または両方がスパッタ法にて成膜されることを特徴
とする請求項１〜４何れか１項記載の光学薄膜。5. The optical thin film according to claim 1, wherein one or both of the aluminum oxide layer and the silicon oxide layer are formed by a sputtering method.
片方または両方がイオンプレーティング法にて成膜され
ることを特徴とする請求項１〜４何れか１項記載の光学
薄膜。6. The optical thin film according to claim 1, wherein one or both of the aluminum oxide layer and the silicon oxide layer are formed by an ion plating method.
片方または両方がイオンビームアシスト蒸着法にて成膜
されることを特徴とする請求項１〜４何れか１項記載の
光学薄膜。7. The optical thin film according to claim 1, wherein one or both of the aluminum oxide layer and the silicon oxide layer are formed by an ion beam assisted vapor deposition method.
光学薄膜とを具えた光学素子。8. An optical element comprising an optical substrate and the optical thin film according to claim 1.
ーザ耐久性が向上された光学装置。9. An optical device incorporating the optical element according to claim 8 and having improved laser durability.
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|---|---|---|---|
| JP24633899A JP2001074931A (en) | 1999-08-31 | 1999-08-31 | Optical thin film, optical element and optical device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24633899A JP2001074931A (en) | 1999-08-31 | 1999-08-31 | Optical thin film, optical element and optical device |
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| Publication Number | Publication Date |
|---|---|
| JP2001074931A true JP2001074931A (en) | 2001-03-23 |
Family
ID=17147088
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24633899A Pending JP2001074931A (en) | 1999-08-31 | 1999-08-31 | Optical thin film, optical element and optical device |
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| Country | Link |
|---|---|
| JP (1) | JP2001074931A (en) |
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