JP2001174226A - Method for measuring film thickness of optical element and method for manufacturing the element - Google Patents
Method for measuring film thickness of optical element and method for manufacturing the elementInfo
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- JP2001174226A JP2001174226A JP36078899A JP36078899A JP2001174226A JP 2001174226 A JP2001174226 A JP 2001174226A JP 36078899 A JP36078899 A JP 36078899A JP 36078899 A JP36078899 A JP 36078899A JP 2001174226 A JP2001174226 A JP 2001174226A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、表面に反射防止膜
等の多層膜を有する光学素子の膜厚の測定方法、その光
学素子の製造方法に関するものである。[0001] 1. Field of the Invention [0002] The present invention relates to a method for measuring the thickness of an optical element having a multilayer film such as an antireflection film on the surface, and a method for manufacturing the optical element.
【０００２】[0002]
【従来の技術】レンズや反射鏡等の光学素子には、反射
防止を行ったり、波長ごとの透過率や反射率を所定の特
性にしたり、波長ごとの位相特性を所定の特性にしたり
するために、その表面に多層膜が成膜されることが多
い。この多層膜の層数は数十層に達するものがあり、多
層膜を構成する各膜の厚さを制御することにより、所定
の特性を得るようになっている。2. Description of the Related Art An optical element such as a lens or a reflecting mirror is used to prevent reflection, to set transmittance and reflectance for each wavelength to predetermined characteristics, and to set phase characteristics for each wavelength to predetermined characteristics. In many cases, a multilayer film is formed on the surface. The number of layers of this multilayer film may reach several tens, and a predetermined characteristic is obtained by controlling the thickness of each film constituting the multilayer film.
【０００３】図１に、このような多層膜を成膜する方法
の例を示す。図１において、(a)は回転テーブルを下か
ら見た図、(b)はＡ−Ａ’位置での装置の端面図を示
す。真空チャンバー１の中には基板ホルダー２が設けら
れ、回転軸３のまわりに回転している。基板ホルダー２
の下面には、表面に成膜を施す光学素子４が同心円状に
取り付けられているが、光学素子４を取り付ける場所の
１ヶ所にはモニター基板５が取り付けられている。FIG. 1 shows an example of a method for forming such a multilayer film. In FIG. 1, (a) is a view of the rotary table viewed from below, and (b) is an end view of the apparatus at AA ′ position. A substrate holder 2 is provided in the vacuum chamber 1 and rotates around a rotation axis 3. Substrate holder 2
An optical element 4 for forming a film on the surface is mounted concentrically on the lower surface of the optical disk, and a monitor substrate 5 is mounted at one place where the optical element 4 is mounted.
【０００４】真空チャンバー１の下部にはスパッター装
置６が設けられ、そこから膜を構成する成分の粒子が飛
び出して、光学素子４とモニター基板５の表面に当たっ
て膜を形成する。また、真空チャンバー１の一部には、
上下面に窓７が設けられており、投光器８より照射され
た光が、光学素子４又はモニター基板５を透過して受光
器９で受光され、分光透過率が測定できるようになって
いる。この分光透過率の測定は、膜厚測定のために行な
われるものである。[0004] A sputtering device 6 is provided below the vacuum chamber 1, from which particles of the constituents of the film fly out and strike the optical element 4 and the surface of the monitor substrate 5 to form a film. Also, in a part of the vacuum chamber 1,
Windows 7 are provided on the upper and lower surfaces, and the light emitted from the light projector 8 passes through the optical element 4 or the monitor substrate 5 and is received by the light receiver 9 so that the spectral transmittance can be measured. The measurement of the spectral transmittance is performed for measuring the film thickness.
【０００５】モニター基板５は、透明な平板からなるも
のであり、膜厚測定のために用いられるダミー光学素子
である。すなわち、光学素子４はレンズのように一般に
その表面が曲面であるため、膜厚を正確に測定すること
ができない。そのため、平板のモニター基板５を配置
し、その上に成膜された膜の厚さを測定することによ
り、それと同条件で成膜される光学素子４上の膜厚を間
接的に測定するものである。[0005] The monitor substrate 5 is formed of a transparent flat plate, and is a dummy optical element used for measuring a film thickness. That is, since the surface of the optical element 4 is generally a curved surface like a lens, the film thickness cannot be measured accurately. Therefore, a flat monitor substrate 5 is arranged, and the thickness of the film formed thereon is measured, thereby indirectly measuring the film thickness on the optical element 4 formed under the same conditions. It is.
【０００６】図１に示すような装置を用いた多層膜の成
膜は、以下のようにして行なわれる。まず、所定の光学
特性（反射率、透過率、位相特性等）が得られるよう
に、計算により膜の材質、層数、各層の厚さが決定され
る。このようにして設計が終了すると、まず、第１層の
成膜が行なわれる。膜厚の測定が基板ホルダー２の回転
を止めずに行なえる場合には、モニター基板５が投光器
８と受光器９の位置を通り過ぎる毎に分光透過率の測定
を行い、後に述べるような方法を使用して膜厚を測定す
る。もちろん、所定の膜厚を形成するために必要な概略
の時間は計算により求まるので、膜厚の測定は、この時
間に近い時間が経過してから実施するようにしてもよ
い。The formation of a multilayer film using an apparatus as shown in FIG. 1 is performed as follows. First, the material of the film, the number of layers, and the thickness of each layer are determined by calculation so as to obtain predetermined optical characteristics (reflectance, transmittance, phase characteristics, and the like). When the design is completed in this way, first, the first layer is formed. If the measurement of the film thickness can be performed without stopping the rotation of the substrate holder 2, the spectral transmittance is measured each time the monitor substrate 5 passes the positions of the light emitter 8 and the light receiver 9, and a method described later is used. Use and measure the film thickness. Of course, the approximate time required to form the predetermined film thickness can be obtained by calculation, so that the film thickness measurement may be performed after a time close to this time has elapsed.
【０００７】膜厚の測定が基板ホルダー２の回転を止め
ないと行なえない場合には、所定の膜厚を形成するため
に必要な時間に近い時間が経過してから、周期的に基板
ホルダー２の回転を止めて測定を行なう。この際、スパ
ッター装置６からの粒子が特定の光学素子４に付着しな
いようにするために、スパッター装置６とその直上の光
学素子４の間をシャッターにより遮蔽する。If the measurement of the film thickness cannot be performed unless the rotation of the substrate holder 2 is stopped, the substrate holder 2 is periodically rotated after a time close to the time required to form a predetermined film thickness. Stop the rotation and measure. At this time, in order to prevent particles from the sputter device 6 from adhering to the specific optical element 4, the shutter is shielded between the sputter device 6 and the optical element 4 immediately above it.
【０００８】このようにして、膜厚を測定しながら成膜
を続け、測定光学特性が参照光学特性に等しくなったと
ころで第１層目の成膜を終了する。そして、スパッター
に用いる材料を変更して、第２層目の成膜を行う。以
下、同様にして最終膜までの成膜を行なう。[0008] In this way, the film formation is continued while measuring the film thickness, and when the measured optical characteristics become equal to the reference optical characteristics, the film formation of the first layer is completed. Then, the material used for the sputtering is changed, and the second layer is formed. Hereinafter, film formation up to the final film is similarly performed.
【０００９】以下、分光透過率に基づいて膜厚を測定す
る方法の原理を図２に基づいて説明する。図２におい
て、(a)はモニター基板５の上に、多層薄膜Ｍが成膜さ
れている状態を示している。多層薄膜Ｍは、Ｍ１〜Ｍｎ
までのｎ層が成膜された状態となっており、この状態で
第ｎ層の薄膜Ｍｎの厚さｄｎを測定するものとする。こ
のとき測定されるのは、多層薄膜Ｍ全体とモニター基板
５によって決定される分光透過率である。すなわち、こ
のときの分光透過率をＴｎとすると、ＴｎはThe principle of the method for measuring the film thickness based on the spectral transmittance will be described below with reference to FIG. 2A shows a state in which a multilayer thin film M is formed on the monitor substrate 5. FIG. The multilayer thin film M is composed of M1 to Mn.
In this state, the thickness dn of the thin film Mn of the n-th layer is to be measured. What is measured at this time is the spectral transmittance determined by the entire multilayer thin film M and the monitor substrate 5. That is, assuming that the spectral transmittance at this time is Tn, Tn is
【００１０】[0010]
【数１】 Tn = Tn(λ,d1,d2,…d(n-1),dn,a1,a2,…a(n-1),an) …(1) で決定される。ここにｄｉ（ｉ＝１〜ｎ）は第ｉ層の厚
さであり、ａｉ（ｉ＝１〜ｎ）は第ｉ層の材質によって
決定される値である。厳密に言えば、モニター基板５の
厚さと材質も関係するが、これは一定であるとして(1)
式では無視している。Tn = Tn (λ, d1, d2,..., D (n-1), dn, a1, a2,... A (n-1), an) (1) Here, di (i = 1 to n) is the thickness of the i-th layer, and ai (i = 1 to n) is a value determined by the material of the i-th layer. Strictly speaking, the thickness and the material of the monitor substrate 5 are also related, but assuming that this is constant (1)
Ignored in the formula.
【００１１】第ｎ層の厚さを測定する場合には、(1)式
においてｄ１〜ｄ（ｎ−１）とａ１〜ａｎは既知であ
る。ここで、ｄｎの目標値をｄｎ0として、(1)式にｄｎ
0を代入して分光透過率を計算する。その結果が例えば
図２(b)のＡ（実線）で示される曲線になったとする。
これに対し、ｄｎがｄｎ0＋Δ、ｄｎ0−Δとなったとし
て、これらの値を(1)式に代入して分光透過率を計算す
る。その結果は、それぞれ図２(b)のＢ（破線）、Ｃ
（一点鎖線）で示されるように、Δ、−Δの値に対応し
て、Ａで示される曲線からずれる。When measuring the thickness of the n-th layer, d1 to d (n-1) and a1 to an in equation (1) are known. Here, assuming that the target value of dn is dn 0 , dn
Calculate the spectral transmittance by substituting 0 . It is assumed that the result is a curve indicated by A (solid line) in FIG. 2B, for example.
On the other hand, assuming that dn becomes dn 0 + Δ and dn 0 −Δ, these values are substituted into the expression (1) to calculate the spectral transmittance. The results are shown by B (broken line) and C in FIG.
As indicated by the dashed line, the curve deviates from the curve indicated by A corresponding to the values of Δ and −Δ.
【００１２】このように、ｄｎを目標値ｄｎ0から±ｍ
Δ（ｍは適当な整数）ずらせた場合に得られる分光透過
率曲線を予め計算しておき、実際に測定された分光透過
率曲線に一番近いものを選択し、それに対応する膜厚を
測定膜厚とする。具体的には、計算された分光透過率を
Ｔ（ｄｎ0＋ｉΔ，λ）（ｉ＝−ｍ〜ｍ）、実測された
分光透過率をＴａ（λ）とすると、As described above, dn is set to ± m from target value dn 0.
Calculate in advance the spectral transmittance curve obtained when shifting Δ (m is an appropriate integer), select the one closest to the actually measured spectral transmittance curve, and measure the film thickness corresponding to it Film thickness. Specifically, assuming that the calculated spectral transmittance is T (dn 0 + iΔ, λ) (i = −m to m) and the actually measured spectral transmittance is Ta (λ),
【００１３】[0013]
【数２】 (Equation 2)
【００１４】を各ｉについて求め、Ｓの値が最も小さく
なるｉを採用する。ただし、(2)式の積分範囲は分光透
過率の測定範囲とする。また、実際には(2)式の代わり
にサンプル値を用いた数値計算によって積分値を求める
ことはいうまでもない。さらに、２乗計算の代わりに絶
対値を用いてもよい。Is obtained for each i, and i that minimizes the value of S is adopted. However, the integration range of the expression (2) is the measurement range of the spectral transmittance. In addition, it goes without saying that an integral value is actually obtained by numerical calculation using a sample value instead of the equation (2). Further, an absolute value may be used instead of the square calculation.
【００１５】[0015]
【発明が解決しようとする課題】以上説明したように、
多層膜の各層の膜厚を求めるには、分光透過率や分光反
射率等の光学特性を測定し、目標とする膜厚での光学特
性からのずれ量に基づいて膜厚を測定している。しかし
ながら、近赤外用、赤外線用に使用される光学素子にお
いては、波長が長くなる関係から各層の膜厚が厚くな
る。このような多層膜の膜厚を、通常の可視光に使用さ
れる多層膜の膜厚を測定する測定器で測定しようとする
と、一般に可視光域での光学特性が波長に応じて大きく
急峻に変化するために、正確な測定ができないという問
題点が発生し、この傾向は多層膜の層数が増えるに従っ
て顕著となる。As described above,
To determine the film thickness of each layer of the multilayer film, optical characteristics such as spectral transmittance and spectral reflectance are measured, and the film thickness is measured based on the amount of deviation from the optical characteristics at the target film thickness. . However, in an optical element used for near-infrared rays and infrared rays, the thickness of each layer is increased due to an increase in wavelength. When trying to measure the film thickness of such a multilayer film with a measuring instrument that measures the film thickness of the multilayer film used for ordinary visible light, generally, the optical characteristics in the visible light region greatly and sharply according to the wavelength. Due to the change, a problem that accurate measurement cannot be performed occurs, and this tendency becomes more remarkable as the number of layers of the multilayer film increases.
【００１６】この様子を図３に示す。図３は、長波長透
過フィルターの膜が２１層形成された段階での分光透過
率の例を赤外領域まで示した図であり、縦軸は、測定器
で測定する光学特性である分光透過率、横軸は波長を示
す。図３に示すように、この分光透過率は950nm以上の
赤外領域においてはそれほど大きな変化を示していない
が、950nmから可視光領域においては波長の変化に対し
て大きく、かつ急峻な繰り返し変化を示すようになる。
この理由は、短波長領域において各多層膜境界での反射
光が重なり合って高次の干渉を起こすためであり、この
干渉の結果生じる分光特性は、一般に波長依存性が急峻
となるからである。FIG. 3 shows this state. FIG. 3 is a diagram showing an example of the spectral transmittance up to the infrared region at the stage when 21 layers of the long-wavelength transmission filter are formed, and the vertical axis indicates the spectral transmittance which is an optical characteristic measured by a measuring instrument. The rate and the abscissa indicate the wavelength. As shown in FIG. 3, this spectral transmittance does not show a large change in the infrared region of 950 nm or more, but shows a large and steep repetitive change with respect to the wavelength change from 950 nm to the visible light region. As shown.
The reason for this is that, in the short wavelength region, reflected lights at the boundaries of the multilayer films overlap to cause higher-order interference, and spectral characteristics resulting from this interference generally have sharp wavelength dependence.
【００１７】一方、分光透過率を測定する測定器の分解
能は、主として分光器の分解能で決定され、一般に図４
(a)に示すような感度分布を有している。すなわち、あ
る波長の受光量として検出されるのは、その波長の光の
みでなく、その波長を中心とするある帯域の波長の光で
ある。そのため図４(b)に示すような理想的なδ関数形
の波長特性を有する光が受光器に入射した場合でも、観
測される分光透過率はδ関数型とならず、図４(c)に示
すようになまってしまう。On the other hand, the resolution of a measuring instrument for measuring the spectral transmittance is mainly determined by the resolution of the spectroscope, and generally, the resolution of the measuring instrument shown in FIG.
It has a sensitivity distribution as shown in FIG. That is, what is detected as the amount of received light of a certain wavelength is not only light of that wavelength, but also light of a certain wavelength band centered on that wavelength. Therefore, even when light having an ideal δ function type wavelength characteristic as shown in FIG. 4B enters the light receiver, the observed spectral transmittance does not become the δ function type, and FIG. It becomes as shown in.
【００１８】よって、従来技術の欄で説明したように、
計算された分光透過率と実測された分光透過率を比較す
ることによって膜厚を決定しようとすると誤差が大きく
なってしまうという問題点がある。このような問題を避
けるためには、赤外に感度を有する測定器を使用して光
学特性を測定すればよいが、すると、赤外用の測定器を
使用しなければならない。赤外線用測定器は装置が高価
となるばかりでなく、測定ノイズが大きく、また、可視
光用の光学素子を測定する場合と測定器を共用できない
という問題点がある。Therefore, as described in the section of the prior art,
There is a problem that an error increases when trying to determine the film thickness by comparing the calculated spectral transmittance with the actually measured spectral transmittance. In order to avoid such a problem, the optical characteristics may be measured using a measuring device having sensitivity to infrared rays. However, a measuring instrument for infrared rays must be used. The measuring instrument for infrared rays has problems that not only the equipment becomes expensive, but also measurement noise is large, and that the measuring instrument cannot be shared with the case of measuring the optical element for visible light.
【００１９】本発明はこのような事情に鑑みてなされた
もので、測定器で光学特性を測定した場合に、その測定
器の分解能によって測定値がなまり、正確な測定ができ
ないような場合においても、その測定器を使用して正確
な膜厚測定を行なう方法、及びその方法を利用した光学
素子の製造方法を提供することを課題とする。The present invention has been made in view of such circumstances, and even when an optical characteristic is measured by a measuring instrument, the measured value is distorted by the resolution of the measuring instrument, and accurate measurement cannot be performed. It is therefore an object of the present invention to provide a method for performing accurate film thickness measurement using the measuring instrument, and a method for manufacturing an optical element using the method.
【００２０】[0020]
【課題を解決するための手段】前記課題を解決するため
の第１の手段は、表面に多層膜を有する光学素子におけ
る、多層膜を構成する各々の膜の厚さを測定する方法で
あって、種々の膜厚のときに観測される分光特性を計算
によって求め、求められた分光特性を測定器の感度特性
又はその近似値によって補正した補正分光特性を求め、
実際に測定された分光特性と前記補正分光特性とのフィ
ッティング計算を行なうことにより膜厚を求めることを
特徴とする光学素子の膜厚測定方法（請求項１）であ
る。According to a first aspect of the present invention, there is provided a method for measuring a thickness of each of films constituting a multilayer film in an optical element having a multilayer film on a surface. Calculating the spectral characteristics observed at various film thicknesses, calculating the corrected spectral characteristics by correcting the obtained spectral characteristics with the sensitivity characteristic of the measuring instrument or an approximate value thereof,
A film thickness measuring method for an optical element, wherein a film thickness is obtained by performing a fitting calculation between the actually measured spectral characteristics and the corrected spectral characteristics.
【００２１】本手段においては、計算によって求められ
た分光特性を、測定器の感度特性又はその近似値で補正
して補正分光特性を求めている。ここで「感度特性」と
は、図４(a)で示したような、分解能を決定する感度特
性である。すなわち、補正分光特性は、計算によって求
められた分光特性を測定器で観測したときに得られるは
ずの分光特性となる。よって、実際に測定された分光特
性と前記補正分光特性とのフィッティング計算を行なう
ことにより、従来技術の欄で説明した方法と同様の方法
で膜厚を求めるようにすれば、計算で求められた分光特
性が測定器で測定できないような急峻な変化を含むよう
な場合でも、正確に膜厚を決定することができる。In this means, the corrected spectral characteristic is obtained by correcting the spectral characteristic obtained by calculation with the sensitivity characteristic of the measuring instrument or an approximate value thereof. Here, the “sensitivity characteristic” is a sensitivity characteristic for determining the resolution as shown in FIG. That is, the corrected spectral characteristic is a spectral characteristic that should be obtained when the spectral characteristic obtained by calculation is observed by the measuring instrument. Therefore, by performing a fitting calculation between the actually measured spectral characteristics and the corrected spectral characteristics, the film thickness is obtained by the same method as the method described in the section of the related art. Even when the spectral characteristics include a steep change that cannot be measured by a measuring instrument, the film thickness can be accurately determined.
【００２２】なお、本明細書において「フィッティング
計算」とは、あるパラメータによって決定される計算量
と実際に観測された量の比較を行い、最も観測された量
に近い計算量を与えるパラメータを採用する計算をい
い、比較の方法として最小２乗法や、差の絶対値の和の
最小を与えるパラメータを求める方法、相互相関係数を
求めて最も大きな相互相関係数が得られるパラメーター
を採用する方法等が代表的なものである。In this specification, the term "fitting calculation" refers to a comparison between a calculation amount determined by a certain parameter and an actually observed amount, and adopts a parameter that gives a calculation amount closest to the most observed amount. The least squares method, a method to find the parameter that gives the minimum sum of the absolute values of the differences, and a method to find the cross-correlation coefficient and use the parameter that gives the largest cross-correlation coefficient Etc. are typical.
【００２３】前記課題を解決するための第２の手段は、
表面に多層膜を有する光学素子における、多層膜を構成
する各々の膜の厚さを測定する方法であって、種々の膜
厚のときに観測される分光特性を計算によって求め、一
方、実際に測定された分光特性と測定器の感度特性又は
その近似値より、真の分光特性を求め、前記計算によっ
て求められた分光特性と前記真の分光特性とのフィッテ
ィング計算を行なうことにより膜厚を求めることを特徴
とする光学素子の膜厚測定方法（請求項２）である。A second means for solving the above-mentioned problem is:
In an optical element having a multilayer film on its surface, a method for measuring the thickness of each film constituting the multilayer film, wherein spectral characteristics observed at various film thicknesses are obtained by calculation, A true spectral characteristic is obtained from the measured spectral characteristic and the sensitivity characteristic of the measuring instrument or an approximate value thereof, and a film thickness is obtained by performing a fitting calculation between the spectral characteristic obtained by the above calculation and the true spectral characteristic. A method for measuring the film thickness of an optical element (claim 2).
【００２４】本手段においては、前記第１の手段と逆
に、実際に測定された分光特性から、測定器の感度特性
又はその近似値を考慮して真の分光特性を求める。ここ
で「感度特性」とは、図４(a)で示したような、分解能
を決定する感度特性である。そして、この真の分光特性
と計算によって求められた分光特性とのフィッティング
計算を行なうことにより、従来技術の欄で説明した方法
と同様の方法で膜厚を求めるようにすれば、計算で求め
られた分光特性が測定器で測定できないような急峻な変
化を含むような場合でも、正確に膜厚を決定することが
できる。In the present means, contrary to the first means, the true spectral characteristic is obtained from the actually measured spectral characteristic in consideration of the sensitivity characteristic of the measuring instrument or its approximate value. Here, the “sensitivity characteristic” is a sensitivity characteristic for determining the resolution as shown in FIG. Then, by performing a fitting calculation between the true spectral characteristics and the spectral characteristics obtained by the calculation, the film thickness can be obtained by the same method as that described in the section of the related art. Even when the spectral characteristics include a steep change that cannot be measured by a measuring instrument, the film thickness can be accurately determined.
【００２５】前記課題を解決するための第３の手段は、
表面に多層膜を有する光学素子における、多層膜を構成
する各々の膜の厚さを測定する方法であって、種々の膜
厚のときに観測される分光特性を計算によって求めると
共に、求められた分光特性を測定器の感度特性又はその
近似値によって補正した補正分光特性を求め、両者の差
が所定値以上である波長範囲を求め、この範囲を除いた
範囲、又はこの範囲を含む所定範囲を除いた範囲におい
て、計算によって求められた分光特性と実際に測定され
た分光特性とのフィッティング計算を行なうことにより
膜厚を求めることを特徴とする光学素子の膜厚測定方法
（請求項３）である。A third means for solving the above-mentioned problem is:
In an optical element having a multilayer film on the surface, a method for measuring the thickness of each film constituting the multilayer film, wherein the spectral characteristics observed at various film thicknesses are obtained by calculation and obtained. Obtain a corrected spectral characteristic in which the spectral characteristic is corrected by the sensitivity characteristic of the measuring instrument or an approximate value thereof, obtain a wavelength range in which the difference between them is equal to or more than a predetermined value, and determine a range excluding this range, or a predetermined range including this range. In the excluded range, a film thickness is obtained by performing a fitting calculation between the spectral characteristics obtained by calculation and the actually measured spectral characteristics. is there.
【００２６】本手段においては、比較の基準となる計算
によって求められた分光特性と、それを測定したとき観
測されると考えられる分光特性の差が大きくなる部分を
フィッティング計算の範囲から除外しているので、計算
で求められた分光特性が測定器で測定できないような急
峻な変化を含むような場合でも、正確に膜厚を決定する
ことができる。この場合「所定値」をいくらにするか
は、計算によって求めた光学特性の形状等を考慮して、
なるべく正確な膜厚測定精度が得られるように、当業者
が適宜経験により決定することができる。In this means, a part where the difference between the spectral characteristic obtained by the calculation serving as the reference for comparison and the spectral characteristic considered to be observed when the spectral characteristic is measured becomes large is excluded from the range of the fitting calculation. Therefore, the film thickness can be accurately determined even when the calculated spectral characteristics include a steep change that cannot be measured by a measuring instrument. In this case, the value of the "predetermined value" is determined in consideration of the shape of the optical characteristics obtained by calculation,
A person skilled in the art can appropriately determine the film thickness measurement accuracy based on experience so as to obtain as accurate a film thickness measurement accuracy as possible.
【００２７】また、「この範囲を含む所定範囲」とは、
例えば、当該範囲の前後所定範囲の波長域を含む範囲、
また、当該範囲が近接した波長域に不連続に複数ある場
合は、そのうち最短の波長から最長の波長までの全ての
連続した範囲、さらにその連続した範囲の前後所定範囲
をも含む範囲とか、種々の範囲が考えられる。The “predetermined range including this range” is
For example, a range including a predetermined wavelength range before and after the range,
In addition, when the range is discontinuous in a plurality of adjacent wavelength ranges, all the continuous ranges from the shortest wavelength to the longest wavelength among them, a range including a predetermined range before and after the continuous range, and various other ranges. Range is conceivable.
【００２８】前記課題を解決するための第４の手段は、
表面に多層膜を有する光学素子における、多層膜を構成
する膜の各々の厚さを測定する方法であって、種々の膜
厚のときに観測される分光特性を計算によって求め、こ
のうち、測定器の分解能に対応する波長間における分光
特性の変化が所定値以上である範囲を求め、この範囲を
除いた範囲、又はこの範囲を含む所定範囲を除いた範囲
において、計算によって求められた分光特性と実際に測
定された分光特性とのフィッティング計算を行なうこと
により膜厚を求めることを特徴とする光学素子の膜厚測
定方法（請求項４）である。A fourth means for solving the above-mentioned problem is:
In an optical element having a multilayer film on the surface, a method for measuring the thickness of each of the films constituting the multilayer film, wherein spectral characteristics observed at various film thicknesses are obtained by calculation, and the measurement is performed. The range in which the change in spectral characteristics between wavelengths corresponding to the resolution of the detector is equal to or greater than a predetermined value is obtained, and the spectral characteristics obtained by calculation in the range excluding this range or in the range excluding the predetermined range including this range The thickness of the optical element is measured by performing a fitting calculation between the measured values and spectral characteristics actually measured.
【００２９】本手段は、計算された分光特性が波長に対
して急峻に変化し、測定器で正確に測定できない範囲を
フィッティング計算に用いる範囲から除外することを骨
子としている。すなわち、測定器の分解能（通常半値幅
で表されることが多い）に対応する波長間隔での光学特
性変化量が所定値以上の場合は、真の値と測定値との間
に大きな誤差が出るとして、この範囲をフィッティング
計算に使用する範囲から除外する。この場合「所定値」
をいくらにするかは、計算によって求めた光学特性の形
状等を考慮して、なるべく正確な膜厚測定精度が得られ
るように、当業者が適宜経験により決定することができ
る。本手段においては、測定精度の悪い部分をフィッテ
ィング計算から除外しているので、計算で求められた分
光特性が測定器で測定できないような急峻な変化を含む
ような場合でも、正確に膜厚を決定することができる。The main feature of this means is to exclude from the range used for fitting calculation the range in which the calculated spectral characteristics change sharply with respect to the wavelength and cannot be measured accurately by the measuring instrument. In other words, when the amount of change in the optical characteristics at a wavelength interval corresponding to the resolution of the measuring instrument (usually often expressed by a half width) is equal to or greater than a predetermined value, a large error occurs between the true value and the measured value. As a result, this range is excluded from the range used for the fitting calculation. In this case "predetermined value"
Can be appropriately determined by a person skilled in the art based on experience so as to obtain as accurate a film thickness measurement accuracy as possible in consideration of the shape of the optical characteristics obtained by calculation and the like. In this method, the portion with poor measurement accuracy is excluded from the fitting calculation, so that even when the spectral characteristics obtained by calculation include a steep change that cannot be measured by a measuring instrument, the film thickness can be accurately determined. Can be determined.
【００３０】また、「この範囲を含む所定範囲」とは、
例えば、当該範囲の前後所定範囲の波長域を含む範囲、
また、当該範囲が近接した波長域に不連続に複数ある場
合は、そのうち最短の波長から最長の波長までの全ての
連続した範囲、さらにその連続した範囲の前後所定範囲
をも含む範囲とか、種々の範囲が考えられる。The "predetermined range including this range" is defined as
For example, a range including a predetermined wavelength range before and after the range,
In addition, when the range is discontinuous in a plurality of adjacent wavelength ranges, all the continuous ranges from the shortest wavelength to the longest wavelength among them, a range including a predetermined range before and after the continuous range, and various other ranges. Range is conceivable.
【００３１】前記課題を解決するための第５の手段は、
前記第１の手段から第４の手段のうちいずれか１項に記
載の膜厚測定方法のプロセス、前記第１の手段の膜厚測
定方法又は前記第２の手段の膜厚測定方法と前記第３の
手段の膜厚測定方法とを組み合わせたプロセス、前記第
１の手段の膜厚測定方法又は前記第２の手段の膜厚測定
方法と前記第４の手段の膜厚測定方法とを組み合わせた
プロセスのうち、いずれか１つのプロセスを使用して少
なくとも１層の膜厚を測定するプロセスを有してなるこ
とを特徴とする光学素子の製造方法（請求項５）であ
る。A fifth means for solving the above problem is as follows.
The process of the film thickness measuring method according to any one of the first to fourth means, the film thickness measuring method of the first means or the film thickness measuring method of the second means, A process combining the film thickness measuring method of the third means, the film thickness measuring method of the first means or the film thickness measuring method of the second means, and the film thickness measuring method of the fourth means. A method for manufacturing an optical element, comprising a step of measuring a film thickness of at least one layer by using any one of the processes (claim 5).
【００３２】本手段においては、計算で求められた分光
特性が測定器で測定できないような急峻な変化を含むよ
うな場合でも、正確に膜厚を決定することができるの
で、多層膜の有する光学特性を所望の特性に正確に制御
することができる。特に、前記第１の手段の膜厚測定方
法又は前記第２の手段の膜厚測定方法と、前記第３の手
段の膜厚測定方法とを組み合わせて使用すれば、さらに
膜厚の測定精度を良くすることができ、多層膜の有する
光学特性を所望の特性に正確に制御することができる。
この効果は、前記第１の手段の膜厚測定方法又は前記第
２の手段の膜厚測定方法と、前記第４の手段の膜厚測定
方法とを組み合わせて使用しても同様に得られる。According to this means, the film thickness can be accurately determined even when the spectral characteristics obtained by calculation include a sharp change that cannot be measured by a measuring instrument. Characteristics can be accurately controlled to desired characteristics. In particular, when the film thickness measuring method of the first means or the film thickness measuring method of the second means is used in combination with the film thickness measuring method of the third means, the film thickness measuring accuracy can be further improved. The optical characteristics of the multilayer film can be accurately controlled to desired characteristics.
This effect can be similarly obtained by using the film thickness measuring method of the first means or the film thickness measuring method of the second means in combination with the film thickness measuring method of the fourth means.
【００３３】[0033]
【発明の実施の形態】以下本発明の実施の形態の第１の
例を詳細に説明する。以下の説明において、膜厚の測定
法自体は、従来技術の説明の欄において説明したよう
に、計算によって求められた分光透過率と実測された分
光透過率のフィッティングにより求めるものとする。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail. In the following description, the method of measuring the film thickness itself is determined by fitting the calculated spectral transmittance and the actually measured spectral transmittance, as described in the description of the related art.
【００３４】分光透過率測定器の分解能を示す感度特性
（以下、単に感度特性という）が、観測すべき波長をλ
とするとき、波長λ’に対してＡ（λ，λ’）で表され
るとする。通常の場合は、感度特性を表す関数の形はλ
によらないので、Ａ（λ，λ’）は、Ａ（λ，λ’）＝
Ｂ（λ−λ’）という関数形で表されることが多い。The sensitivity characteristic indicating the resolution of the spectral transmittance measuring device (hereinafter simply referred to as the sensitivity characteristic) indicates that the wavelength to be observed is λ.
Let A (λ, λ ′) be represented by wavelength λ ′. In the normal case, the form of the function representing the sensitivity characteristic is λ
A (λ, λ ′) is given by A (λ, λ ′) =
It is often represented by a function form of B (λ−λ ′).
【００３５】ある膜厚ｄのとき観測される分光透過率を
計算によって求めた値を、Ｔ（ｄ，λ）とすると、次式
により補正分光透過率Ｔ’（ｄ，λ）を求める。Assuming that a value obtained by calculating the spectral transmittance observed at a certain film thickness d is T (d, λ), a corrected spectral transmittance T ′ (d, λ) is obtained by the following equation.
【００３６】[0036]
【数３】 (Equation 3)
【００３７】ただし、積分範囲は、分光透過率測定器の
感度がある波長範囲内でフィッティング計算に用いる範
囲とする。そしてこのようにして求められた補正分光透
過率Ｔ’（ｄ，λ）を計算によって求められた分光透過
率の代わりに使用して(2)式におけるＴ（ｄｎ0＋ｉΔ，
λ）（ｉ＝−ｍ〜ｍ）を求め、従来技術の欄において説
明した方法と同じ方法を用いて、フィッティング計算に
より(2)式のＳが最も小さくなるｉを採用することによ
り、膜厚を求める。実際には(3)式の代わりにサンプル
値を用いた数値計算によって積分値を求める。また、Ａ
（λ，λ’）の関数形は近似値を用いたものにしてもよ
い。However, the integration range is a range used for fitting calculation within a wavelength range where the sensitivity of the spectral transmittance measuring device is within a certain range. Then, the corrected spectral transmittance T ′ (d, λ) obtained in this manner is used instead of the calculated spectral transmittance, and T (dn 0 + iΔ,
λ) (i = −m to m) is determined, and by using the same method as that described in the section of the related art, i is used to minimize S in the equation (2) by fitting calculation to obtain the film thickness. Ask for. Actually, an integral value is obtained by numerical calculation using a sample value instead of the equation (3). Also, A
The function form of (λ, λ ′) may use an approximate value.
【００３８】このような実施の形態を用いることによ
り、計算された分光特性でなく測定器で測定されるはず
の分光透過率と実際に測定された分光透過率のフィッテ
ィングが行われるので、正確に膜厚を求めることができ
る。By using such an embodiment, fitting of the spectral transmittance that should be measured by the measuring device and the actually measured spectral transmittance is performed instead of the calculated spectral characteristics, so that the fitting is performed accurately. The film thickness can be determined.
【００３９】以下、本発明の第２の実施の形態について
詳細に説明する。この実施の形態についても、膜厚の測
定法自体は、従来技術の説明の欄において説明したよう
に、計算によって求められた分光透過率と実測された分
光透過率のフィッティングにより求めるものとする。Hereinafter, a second embodiment of the present invention will be described in detail. Also in this embodiment, it is assumed that the method of measuring the film thickness itself is determined by fitting the calculated spectral transmittance with the actually measured spectral transmittance, as described in the description of the related art.
【００４０】測定された分光透過率をＴａ（λ）とす
る。そして、この実施の形態においても分光透過率測定
器の感度特性が、観測すべき波長をλとするとき、波長
λ’に対してＡ（λ，λ’）で表されるとする。そのと
き、真の分光透過率をＴ（λ）として，積分方程式The measured spectral transmittance is defined as Ta (λ). Also in this embodiment, it is assumed that the sensitivity characteristic of the spectral transmittance measuring device is represented by A (λ, λ ′) with respect to the wavelength λ ′, where λ is the wavelength to be observed. At that time, the integral equation is defined assuming that the true spectral transmittance is T (λ).
【００４１】[0041]
【数４】 (Equation 4)
【００４２】を解いてＴ（λ）を求める。実際には、こ
の積分方程式は数値計算により解かれる。Ａ（λ，
λ’）の関数形は近似値を用いたものにしてもよい。Is solved to obtain T (λ). In practice, this integral equation is solved by numerical calculations. A (λ,
The function form of λ ′) may use an approximate value.
【００４３】このようにして求められたＴ（λ）を用い
て、(2)式のＴａ（λ）の代わりにＴ（λ）を使用した
式Using T (λ) obtained in this way, an equation using T (λ) instead of Ta (λ) in equation (2)
【００４４】[0044]
【数５】 (Equation 5)
【００４５】を各ｉについて求め、Ｓの値が最も小さく
なるｉを採用する。ただし、(2)式の積分範囲は分光透
過率の測定範囲とする。また、実際には(2)式の代わり
にサンプル値を用いた数値計算によって積分値を求める
ことはいうまでもない。さらに、２乗計算の代わりに絶
対値を用いてもよい。Is obtained for each i, and i that minimizes the value of S is adopted. However, the integration range of the expression (2) is the measurement range of the spectral transmittance. In addition, it goes without saying that an integral value is actually obtained by numerical calculation using a sample value instead of the equation (2). Further, an absolute value may be used instead of the square calculation.
【００４６】本手段においては、実際に観測された分光
透過率から、測定器の特性を考慮した積分方程式を解く
ことにより真の分光透過率を求め、これと計算された分
光透過率のフィッティングを行うことにより膜厚を求め
ているので、正確に膜厚を求めることができる。In this means, the true spectral transmittance is obtained from the actually observed spectral transmittance by solving an integral equation in consideration of the characteristics of the measuring instrument, and the fitting of the true spectral transmittance and the calculated spectral transmittance is performed. Since the film thickness is obtained by performing the measurement, the film thickness can be accurately obtained.
【００４７】以下、本発明の第３の実施の形態について
詳細に説明する。この実施の形態についても、膜厚の測
定法自体は、従来技術の説明の欄において説明したよう
に、計算によって求められた分光透過率と実測された分
光透過率のフィッティングにより求めるものとする。Hereinafter, a third embodiment of the present invention will be described in detail. Also in this embodiment, it is assumed that the method of measuring the film thickness itself is determined by fitting the calculated spectral transmittance with the actually measured spectral transmittance, as described in the description of the related art.
【００４８】第１の手段で説明したように、ある膜厚ｄ
のとき観測される分光透過率を計算によって求めた値
を、Ｔ（ｄ，λ）とし、(3)式により計算した補正分光
透過率Ｔ’（ｄ，λ）とＴ（ｄ，λ）の差｜Ｔ（ｄ，
λ）−Ｔ’（ｄ，λ）｜を求める。そして、この差が所
定値を超える波長範囲を、フィッティング計算を行う範
囲から除外する。この所定値は、一定値としてもよい
し、Ｔ（ｄ，λ）の値に所定係数を掛けた値としてもよ
い。As described in the first means, a certain thickness d
The value obtained by calculation of the spectral transmittance observed at the time of is defined as T (d, λ), and the corrected spectral transmittance T ′ (d, λ) and T (d, λ) calculated by equation (3) are calculated. Difference | T (d,
λ) −T ′ (d, λ) | Then, the wavelength range in which the difference exceeds a predetermined value is excluded from the range in which the fitting calculation is performed. This predetermined value may be a constant value or a value obtained by multiplying the value of T (d, λ) by a predetermined coefficient.
【００４９】また、(2)式におけるもとの積分区間を
Ｌ、積分から除外された区間をＬ’とするとき、(2)式
におけるＳの値はＬからＬ’を除いた区間で積分して求
められ、これらの積分は１区間のこともあれば複数区間
のこともある。When the original integration section in the equation (2) is L and the section excluded from the integration is L ′, the value of S in the equation (2) is the integral in the section excluding L ′ from L. These integrals may be for one section or for a plurality of sections.
【００５０】フィッテング計算から除外する範囲として
は、前記の差が所定値を超える波長範囲と共に、その前
後の所定範囲の波長範囲をも除くようにしてもよい。ま
た、前記の差が所定値を超える範囲が、近接して不連続
に複数存在する場合は、そのうち最短の波長から最長の
波長に亘る範囲全体をフィッティング計算から除くよう
にしてもよい。さらに、このようにして決定された連続
した波長域の前後の所定の波長範囲を含めて除くように
してもよい。また、フィッティング計算から除く範囲
は、全ての膜厚測定に共通にしてもよいし、膜厚に応じ
て段階的に変えるようにしてもよい。このようにして決
定された除外範囲は、複数の範囲であることもある。As a range excluded from the fitting calculation, a wavelength range in which the difference exceeds a predetermined value and a wavelength range in a predetermined range before and after the wavelength range may be excluded. When there are a plurality of ranges in which the difference exceeds a predetermined value in close proximity and discontinuously, the entire range from the shortest wavelength to the longest wavelength may be excluded from the fitting calculation. Further, a predetermined wavelength range before and after the continuous wavelength range determined in this way may be excluded. The range excluded from the fitting calculation may be common to all film thickness measurements, or may be changed stepwise according to the film thickness. The exclusion range determined in this way may be a plurality of ranges.
【００５１】以下、本発明の第４の実施の形態について
詳細に説明する。この実施の形態についても、膜厚の測
定法自体は、従来技術の説明の欄において説明したよう
に、計算によって求められた分光透過率と実測された分
光透過率のフィッティングにより求めるものとする。Hereinafter, a fourth embodiment of the present invention will be described in detail. Also in this embodiment, it is assumed that the method of measuring the film thickness itself is determined by fitting the calculated spectral transmittance with the actually measured spectral transmittance, as described in the description of the related art.
【００５２】従来技術の欄において説明したように、計
算された分光透過率をＴ（ｄｎ0＋ｉΔ，λ）（ｉ＝−
ｍ〜ｍ）とする。一方、測定器の感度分布が図４(a)に
示すようになっているとし、その半値幅を分解能として
その値をａとする。そして、(2)式に基づいてフィッテ
ィングを行う際、各計算分光透過率Ｔ（ｄｎ0＋ｉΔ，
λ）（ｉ＝−ｍ〜ｍ）について、波長がａだけ変化した
とき分光透過率の計算値が所定値以上変化する区間を、
(2)式における積分区間から除外する。この所定値は、
一定値としてもよいし、波長がａだけ変化する区間の各
計算分光特性Ｔ（ｄｎ0＋ｉΔ，λ）（ｉ＝−ｍ〜ｍ）
に所定係数を掛けた値としてもよい。As described in the section of the prior art, the calculated spectral transmittance is calculated as T (dn 0 + iΔ, λ) (i = −
m to m). On the other hand, it is assumed that the sensitivity distribution of the measuring instrument is as shown in FIG. Then, when fitting is performed based on equation (2), each calculated spectral transmittance T (dn 0 + iΔ,
λ) (i = -m to m), a section where the calculated value of the spectral transmittance changes by a predetermined value or more when the wavelength changes by a,
Exclude from the integration interval in equation (2). This predetermined value is
It may be a constant value, or each calculated spectral characteristic T (dn 0 + iΔ, λ) in a section where the wavelength changes by a (i = −m to m)
May be multiplied by a predetermined coefficient.
【００５３】また、(2)式における積分区間をＬ、積分
から除外された区間をＬ’とするとき、(2)式における
Ｓの値は、区間ＬからＬ’を除いた区間で積分され、比
較されることはいうまでもない。When the integral section in the equation (2) is L and the section excluded from the integral is L ′, the value of S in the equation (2) is integrated in the section L excluding the section L ′. Needless to say, they are compared.
【００５４】本手段においては、計算された分光特性の
変化が大きくて、測定器で測定した場合に誤差が大きく
なる波長範囲がフィッティング計算から除外されている
ので、正確に膜厚を求めることができる。フィッティン
グ計算から除外する範囲を、前記第３の実施の形態で述
べたような範囲としてもよいことは言うまでも無い。In this means, the wavelength range in which the calculated spectral characteristic changes greatly and the error increases when measured by a measuring instrument is excluded from the fitting calculation. it can. It goes without saying that the range excluded from the fitting calculation may be the range described in the third embodiment.
【００５５】多層膜を成膜する過程において、少なくと
も１層の膜厚をこれら実施の形態に示したような請求項
１から請求項４に記載の膜厚測定方法で測定すれば、光
学特性が波長に対して大きく変化する可視光域において
も、光学特性を計測することにより膜厚を正確に測定す
ることができる。この際、全ての膜の膜厚を同じ測定方
法で計測する必要はなく、膜ごとに請求項１から請求項
４に記載の膜厚測定方法の異なったものを選択して使用
してもよい。In the process of forming a multilayer film, if the film thickness of at least one layer is measured by the film thickness measuring method according to any one of claims 1 to 4, as described in the above embodiments, the optical characteristics can be improved. Even in the visible light range that greatly changes with wavelength, the film thickness can be accurately measured by measuring the optical characteristics. In this case, it is not necessary to measure the film thicknesses of all the films by the same measuring method, and different film thickness measuring methods according to claims 1 to 4 may be selected and used for each film. .
【００５６】また、請求項１に記載の方法又は請求項２
に記載の方法でフィッティング計算を行ない、これに加
えて請求項３又は請求項４に記載の方法でフィッティン
グ計算を行なう範囲を制限すれば、膜厚測定精度をさら
に上げることができる。The method according to the first aspect or the second aspect.
If the fitting calculation is performed by the method described in (1) and the range in which the fitting calculation is performed by the method described in (3) or (4), the film thickness measurement accuracy can be further improved.
【００５７】このようにして成膜が行われた光学素子
は、各層の膜厚が正確な厚さに成膜されているので、確
実に目的とする光学特性を有するものとなる。よって、
このような光学素子を光学装置に組み込めば、光学装置
の性能の向上を図ることができる。また、本発明におけ
る光学素子の製造方法は、光通信用に使用される波長多
重用狭帯域フィルター、長波長透過フィルター等を製造
するのに特に適している。Since the optical element thus formed is formed so that each layer has an accurate thickness, the optical element surely has the desired optical characteristics. Therefore,
By incorporating such an optical element into an optical device, the performance of the optical device can be improved. The method for manufacturing an optical element according to the present invention is particularly suitable for manufacturing a narrow band filter for wavelength division multiplexing, a long wavelength transmission filter, and the like used for optical communication.
【００５８】[0058]
【実施例】（実施例１）近赤外から赤外領域において、
1000nmから1220nmの透過率が５％以下であり、1300nmか
ら1800nmの透過率が85％以上という光学特性を目標と
し、27層からなる多層膜を設計して成膜した。成膜の各
過程において、各膜厚は第１の実施の形態で示したよう
な方法により求め、従来技術の欄で示したような方法で
成膜を行った。得られた多層膜の光学特性の測定結果を
図５に示す。図５から、目標とする光学的特性が得られ
ていることが分かる。(Example 1) In the near infrared to infrared region,
A multilayer film consisting of 27 layers was designed and formed with a target of optical characteristics such that the transmittance from 1000 nm to 1220 nm was 5% or less and the transmittance from 1300 nm to 1800 nm was 85% or more. In each process of the film formation, each film thickness was obtained by the method described in the first embodiment, and the film was formed by the method described in the section of the prior art. FIG. 5 shows the measurement results of the optical characteristics of the obtained multilayer film. FIG. 5 shows that the target optical characteristics are obtained.
【００５９】（実施例２）実施例１と同じ多層膜を、膜
厚を第２の実施の形態に示したような方法により求め、
従来技術の欄で示したような方法で成膜を行った。得ら
れた多層膜の光学特性の測定結果を図６に示す。図６か
ら、目標とする光学的特性が得られていることが分か
る。(Example 2) The same multilayer film as that of Example 1 was obtained by the method as described in the second embodiment for the film thickness.
Film formation was performed by the method shown in the section of the prior art. FIG. 6 shows the measurement results of the optical characteristics of the obtained multilayer film. FIG. 6 shows that the target optical characteristics are obtained.
【００６０】（実施例３）実施例１と同じ多層膜を、膜
厚を第３の実施の形態に示したような方法により求め、
従来技術の欄で示したような方法で成膜を行った。得ら
れた多層膜の光学特性の測定結果を図７に示す。図７に
よると、1315nm付近で透過率が目標の85％を多少割り込
んでいるが、ほぼ目標とする特性が得られているのが分
かる。(Example 3) The same multilayer film as in Example 1 was obtained by the method described in the third embodiment for the film thickness.
Film formation was performed by the method shown in the section of the prior art. FIG. 7 shows the measurement results of the optical characteristics of the obtained multilayer film. According to FIG. 7, the transmittance slightly falls below the target of 85% at around 1315 nm, but it can be seen that the target characteristic is almost obtained.
【００６１】（比較例）実施例１と同じ多層膜を、従来
と同じ方法で可視光領域で膜厚測定を行い、従来技術の
欄で示したような方法で成膜を行った。得られた赤外領
域の光学特性は、図８に示すように目標値を大きく外れ
ており、上記各実施例より大幅に悪化していた。(Comparative Example) The same multilayer film as in Example 1 was measured in the visible light region by the same method as the conventional method, and was formed by the method shown in the section of the prior art. The obtained optical characteristics in the infrared region largely deviated from the target values as shown in FIG. 8, and were much worse than those of the above-described embodiments.
【００６２】[0062]
【発明の効果】以上説明したように、本発明において
は、光学特性を測定する測定器の分解能を越えるような
急峻な光学特性の変化がある場合でも、光学特性の変化
に基づいて、多層膜の各膜厚を正確に決定することがで
き、これにより所望の光学特性を有する光学素子を得る
ことができる。As described above, according to the present invention, even when there is a steep change in optical characteristics exceeding the resolution of a measuring instrument for measuring optical characteristics, the multilayer film is formed based on the change in optical characteristics. Can be accurately determined, whereby an optical element having desired optical characteristics can be obtained.
【図１】多層膜を成膜する方法の例を示す図である。FIG. 1 is a diagram illustrating an example of a method for forming a multilayer film.
【図２】分光透過率に基づいて膜厚を測定する方法の原
理を示す図である。FIG. 2 is a diagram illustrating the principle of a method for measuring a film thickness based on a spectral transmittance.
【図３】分光透過率の例を赤外領域まで示した図であ
る。FIG. 3 is a diagram showing an example of a spectral transmittance up to an infrared region.
【図４】分光透過率測定器の感度特性と、理想的なδ関
数型の波長特性を有する光が入射した場合に観測される
分光透過率の形を示す図である。FIG. 4 is a diagram showing the sensitivity characteristics of a spectral transmittance measuring device and the shape of the spectral transmittance observed when light having an ideal δ function type wavelength characteristic is incident.
【図５】本発明の第１の実施例により得られた多層膜の
光学特性を示す図である。FIG. 5 is a diagram showing optical characteristics of a multilayer film obtained according to the first embodiment of the present invention.
【図６】本発明の第２の実施例により得られた多層膜の
光学特性を示す図である。FIG. 6 is a diagram showing optical characteristics of a multilayer film obtained according to a second embodiment of the present invention.
【図７】本発明の第３の実施例により得られた多層膜の
光学特性を示す図である。FIG. 7 is a diagram showing optical characteristics of a multilayer film obtained according to a third embodiment of the present invention.
【図８】従来の膜厚測定法を使用した成膜方法により得
られた多層膜の光学特性を示す図である。FIG. 8 is a diagram showing optical characteristics of a multilayer film obtained by a film forming method using a conventional film thickness measuring method.
１…真空チャンバー ２…基板ホルダー ３…回転軸 ４…光学素子 ５…モニター基板 ６…スパッター装置 ７…窓 ８…投光器 ９…受光器 Ｍ…多層薄膜 Ｍ１〜Ｍｎ…薄膜 DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber 2 ... Substrate holder 3 ... Rotating axis 4 ... Optical element 5 ... Monitor substrate 6 ... Sputtering apparatus 7 ... Window 8 ... Projector 9 ... Receiver M ... Multilayer thin film M1-Mn ... Thin film
─────────────────────────────────────────────────────
────────────────────────────────────────────────── ───
【手続補正書】[Procedure amendment]
【提出日】平成１３年１月１８日（２００１．１．１
８）[Submission date] January 18, 2001 (2001.1.1)
8)
【手続補正１】[Procedure amendment 1]
【補正対象書類名】明細書[Document name to be amended] Statement
【補正対象項目名】特許請求の範囲[Correction target item name] Claims
【補正方法】変更[Correction method] Change
【補正内容】[Correction contents]
【特許請求の範囲】[Claims]
フロントページの続き (72)発明者 萩原 まゆみ 東京都千代田区丸の内３丁目２番３号 株 式会社ニコン内 Ｆターム(参考） 2F065 AA30 BB17 CC31 DD03 FF51 GG02 JJ01 LL67 QQ17 QQ18 QQ29 QQ41 2K009 AA09 DD04 EE00 4D075 AC92 BB85Z CB02 DC24Continued on the front page (72) Inventor Mayumi Hagiwara 3-2-3 Marunouchi, Chiyoda-ku, Tokyo F-term in Nikon Corporation (Reference) 2F065 AA30 BB17 CC31 DD03 FF51 GG02 JJ01 LL67 QQ17 QQ18 QQ29 QQ41 2K009 AA09 DD04 EE004D AC92 BB85Z CB02 DC24
Claims (5)
る、多層膜を構成する各々の膜の厚さを測定する方法で
あって、種々の膜厚のときに観測される分光特性を計算
によって求め、求められた分光特性を測定器の感度特性
又はその近似値によって補正した補正分光特性を求め、
実際に測定された分光特性と前記補正分光特性とのフィ
ッティング計算を行なうことにより膜厚を求めることを
特徴とする光学素子の膜厚測定方法。1. A method for measuring the thickness of each film constituting a multilayer film in an optical element having a multilayer film on a surface, wherein spectral characteristics observed at various film thicknesses are obtained by calculation. Determining a corrected spectral characteristic obtained by correcting the obtained spectral characteristic by the sensitivity characteristic of the measuring instrument or an approximate value thereof,
A film thickness measuring method for an optical element, wherein a film thickness is obtained by performing fitting calculation between actually measured spectral characteristics and the corrected spectral characteristics.
る、多層膜を構成する各々の膜の厚さを測定する方法で
あって、種々の膜厚のときに観測される分光特性を計算
によって求め、一方、実際に測定された分光特性と測定
器の感度特性又はその近似値より、真の分光特性を求
め、前記計算によって求められた分光特性と前記真の分
光特性とのフィッティング計算を行なうことにより膜厚
を求めることを特徴とする光学素子の膜厚測定方法。2. A method for measuring the thickness of each film constituting a multilayer film in an optical element having a multilayer film on its surface, wherein spectral characteristics observed at various film thicknesses are obtained by calculation. On the other hand, calculating the true spectral characteristic from the actually measured spectral characteristic and the sensitivity characteristic of the measuring instrument or an approximate value thereof, and performing fitting calculation between the spectral characteristic obtained by the above calculation and the true spectral characteristic. A method for measuring the film thickness of an optical element, wherein the film thickness is determined by:
る、多層膜を構成する各々の膜の厚さを測定する方法で
あって、種々の膜厚のときに観測される分光特性を計算
によって求めると共に、求められた分光特性を測定器の
感度特性又はその近似値によって補正した補正分光特性
を求め、両者の差が所定値以上である波長範囲を求め、
この範囲除いた範囲、又はこの範囲を含む所定範囲を除
いた範囲において、計算によって求められた分光特性と
実際に測定された分光特性とのフィッティング計算を行
なうことにより膜厚を求めることを特徴とする光学素子
の膜厚測定方法。3. A method for measuring a thickness of each film constituting a multilayer film in an optical element having a multilayer film on a surface, wherein spectral characteristics observed at various film thicknesses are obtained by calculation. Along with the sensitivity characteristic of the measuring device or a corrected spectral characteristic corrected by an approximate value thereof, a wavelength range in which the difference between them is equal to or more than a predetermined value is determined,
In a range excluding this range, or in a range excluding a predetermined range including this range, the film thickness is obtained by performing fitting calculation between the spectral characteristics obtained by calculation and the actually measured spectral characteristics. Of measuring the thickness of an optical element to be used.
る、多層膜を構成する膜の各々の厚さを測定する方法で
あって、種々の膜厚のときに観測される分光特性を計算
によって求め、このうち、測定器の分解能に対応する波
長間における分光特性の変化が所定値以上である範囲を
求め、この範囲除いた範囲、又はこの範囲を含む所定範
囲を除いた範囲において、計算によって求められた分光
特性と実際に測定された分光特性とのフィッティング計
算を行なうことにより膜厚を求めることを特徴とする光
学素子の膜厚測定方法。4. A method for measuring the thickness of each of films constituting a multilayer film in an optical element having a multilayer film on its surface, wherein spectral characteristics observed at various film thicknesses are obtained by calculation. Of these, a range in which the change in spectral characteristics between wavelengths corresponding to the resolution of the measuring instrument is equal to or more than a predetermined value is obtained, and a range excluding this range or a range excluding the predetermined range including this range is obtained by calculation. A film thickness measuring method for an optical element, wherein a film thickness is obtained by performing a fitting calculation between a measured spectral characteristic and an actually measured spectral characteristic.
項に記載の膜厚測定方法のプロセス、請求項１に記載の
膜厚測定方法又は請求項２に記載の膜厚測定方法と請求
項３に記載の膜厚測定方法とを組み合わせたプロセス、
請求項１に記載の膜厚測定方法又は請求項２に記載の膜
厚測定方法と請求項４に記載の膜厚測定方法とを組み合
わせたプロセスのうち、いずれか１つのプロセスを使用
して少なくとも１層の膜厚を測定するプロセスを有して
なることを特徴とする光学素子の製造方法。5. The method according to claim 1, wherein
A film thickness measurement method according to claim 1, a film thickness measurement method according to claim 1, or a combination of the film thickness measurement method according to claim 2 and a film thickness measurement method according to claim 3,
At least one of the processes of combining the film thickness measuring method of claim 1 and the film thickness measuring method of claim 2 and the film thickness measuring method of claim 4 is used. A method for manufacturing an optical element, comprising a process of measuring the thickness of one layer.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003052468A1 (en) * | 2001-12-19 | 2003-06-26 | Nikon Corporation | Film forming device, and production method for optical member |
| JP2007057521A (en) * | 2005-07-29 | 2007-03-08 | Dainippon Screen Mfg Co Ltd | Unevenness inspecting apparatus and method therefor |
| JP2013190224A (en) * | 2012-03-12 | 2013-09-26 | Konica Minolta Inc | Thickness measurement device and thickness measurement method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0755435A (en) * | 1993-08-20 | 1995-03-03 | Dainippon Screen Mfg Co Ltd | Film thickness measuring method for multilayer film sample |
| JPH10513560A (en) * | 1995-02-09 | 1998-12-22 | フォス エレクトリック アクティーゼルスカブ | Spectrometer standardization method |
-
1999
- 1999-12-20 JP JP36078899A patent/JP3520910B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0755435A (en) * | 1993-08-20 | 1995-03-03 | Dainippon Screen Mfg Co Ltd | Film thickness measuring method for multilayer film sample |
| JPH10513560A (en) * | 1995-02-09 | 1998-12-22 | フォス エレクトリック アクティーゼルスカブ | Spectrometer standardization method |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003052468A1 (en) * | 2001-12-19 | 2003-06-26 | Nikon Corporation | Film forming device, and production method for optical member |
| GB2402741A (en) * | 2001-12-19 | 2004-12-15 | Nikon Corp | Film forming device and production method for optical member |
| GB2402741B (en) * | 2001-12-19 | 2005-08-10 | Nikon Corp | Film forming device and production method for optical member |
| JP2007057521A (en) * | 2005-07-29 | 2007-03-08 | Dainippon Screen Mfg Co Ltd | Unevenness inspecting apparatus and method therefor |
| JP2013190224A (en) * | 2012-03-12 | 2013-09-26 | Konica Minolta Inc | Thickness measurement device and thickness measurement method |
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