JP3087353B2 - Photomask and exposure method using the same - Google Patents
Photomask and exposure method using the sameInfo
- Publication number
- JP3087353B2 JP3087353B2 JP16738391A JP16738391A JP3087353B2 JP 3087353 B2 JP3087353 B2 JP 3087353B2 JP 16738391 A JP16738391 A JP 16738391A JP 16738391 A JP16738391 A JP 16738391A JP 3087353 B2 JP3087353 B2 JP 3087353B2
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- Japan
- Prior art keywords
- light
- pattern
- photomask
- polarized
- transmitting portion
- Prior art date
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- Expired - Lifetime
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- Preparing Plates And Mask In Photomechanical Process (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、半導体素子製造のリソ
グラフィ工程において、被投影原版として用いられるフ
ォトマスク（レチクルともいう）及びこれを用いた露光
方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask (also referred to as a reticle) used as a projection original in a lithography process for manufacturing a semiconductor device, and an exposure method using the same.
【０００２】[0002]
【従来の技術】半導体素子製造のリソグラフィ工程にお
いて、被投影原版として用いられるフォトマスクは、一
般的には、透明基板上にクロム等の金属からなる遮光パ
ターンが形成された構造をなしており、フォトマスクを
透過照明し、投影光学系によって遮光パターンの像をウ
エハ面上に結像することにより、所望の回路パターンを
ウエハ面に転写している。2. Description of the Related Art In a lithography process for manufacturing a semiconductor device, a photomask used as a projection original generally has a structure in which a light-shielding pattern made of a metal such as chromium is formed on a transparent substrate. A desired circuit pattern is transferred to the wafer surface by transmitting and illuminating the photomask and forming an image of the light shielding pattern on the wafer surface by the projection optical system.
【０００３】図３(a) は、光透過部（基板裸面部）１０
２と遮光部（図中遮光部に斜線を付す）１０１とが交互
に繰り返されるラインアンドスペースパターンが形成さ
れた従来のフォトマスクの平面構造を模式的に示したも
ので、かかるフォトマスクの振幅透過率は図３(b) のよ
うになる。図に示されるように、振幅透過率はラインア
ンドスペースパターンの遮光部１０１で低く（＝０）、
光透過部１０２で高くなり、隣り合う一対の遮光部１０
１と光透過部１０２が図３(a) のパターンの基本周期Ｐ
となる。FIG. 3A shows a light transmitting portion (substrate bare surface portion) 10.
2 schematically shows a planar structure of a conventional photomask on which a line-and-space pattern in which light-shielding portions 2 and light-shielding portions (hatched portions are shaded in the figure) 101 are alternately repeated is shown. The transmittance is as shown in FIG. As shown in the figure, the amplitude transmittance is low (= 0) in the light-shielding portion 101 of the line and space pattern,
A pair of light-shielding portions 10 adjacent to each other,
1 and the light transmission portion 102 are the basic period P of the pattern of FIG.
Becomes
【０００４】また、近年、投影像のコントラストを高め
るために、光透過部の特定の箇所に透過光の位相を変化
させる位相シフト部を設けた位相シフトマスクが種々提
案されている。例えば、特公昭６２−５０８１１号公報
には、空間周波数変調型の位相シフトマスクに関する技
術が開示されている。In recent years, in order to enhance the contrast of a projected image, various phase shift masks provided with a phase shift section for changing the phase of transmitted light at a specific portion of the light transmitting section have been proposed. For example, Japanese Patent Publication No. 62-50811 discloses a technique related to a spatial frequency modulation type phase shift mask.
【０００５】図４(a) は空間周期数変調型の位相シフト
マスクの平面構造を模式的に示したもので、ラインアン
ドスペースパターンの一つおきの光透過部１０２ｂに位
相部材が付加され、遮光部１０１を介して隣り合う光透
過部１０２ａ，１０２ｂを透過した光の位相はπずれる
ことになる。この位相シフトマスクの振幅透過率を図４
(b) に示す。図に示されるように、位相部材が付加され
た光透過部１０２ｂと位相部材が付加されていない光透
過部１０２ａを透過した光の振幅は正負が反転するた
め、光透過部１０２ａ（位相部材なし）−遮光部１０１
−光透過部１０２（位相部材有り）−遮光部がパターン
の基本周期Ｐとなる。FIG. 4A schematically shows a plane structure of a phase shift mask of a spatial period modulation type. A phase member is added to every other light transmitting portion 102b of the line and space pattern. The phase of the light transmitted through the adjacent light transmitting portions 102a and 102b via the light shielding portion 101 is shifted by π. FIG. 4 shows the amplitude transmittance of this phase shift mask.
This is shown in (b). As shown in the figure, since the amplitude of the light transmitted through the light transmitting portion 102b to which the phase member is added and the amplitude of the light transmitted through the light transmitting portion 102a to which the phase member is not added are inverted, the light transmitting portion 102a (without the phase member) ) -Shading part 101
-Light transmitting portion 102 (having a phase member)-The light shielding portion is the basic period P of the pattern.
【０００６】[0006]
【発明が解決しようとする課題】しかし、上記のような
従来の技術においては、近年の半導体素子の高集積化に
伴なう回路パターンの微細化に対応できないという問題
点がある。即ち、上述した位相シフトマスクに使用する
ことにより、ある程度結像性能が向上することが認めら
れているが、今だ要求される微細パターンを解像し得る
解像力は確保されていない。However, the conventional techniques as described above have a problem that they cannot cope with the miniaturization of circuit patterns accompanying the recent high integration of semiconductor elements. That is, although it has been recognized that the use of the above-described phase shift mask improves the imaging performance to some extent, the resolving power capable of resolving the required fine pattern has not yet been secured.
【０００７】この発明は、かかる点に鑑みてなされたも
のであり、光の振幅と位相以外の第三の情報を利用する
ことにより、より高い解像力が得られるフォトマスク及
び露光方法を提供することを目的とするものである。The present invention has been made in view of the above points, and provides a photomask and an exposure method that can obtain higher resolution by using third information other than the amplitude and phase of light. It is intended for.
【０００８】[0008]
【課題を解決するための手段】以上の目的を達成するた
めに、本発明のフォトマスクは、投影転写すべきパター
ンが透明基板上に形成されたフォトマスクにおいて、前
記透明基板の光透過部に、相互に直交する各偏光状態に
変換する少なくとも２種の偏光部材が繰り返し形成さ
れ、前記２種の偏光部材は、前記パターンの辺に対して
傾いた方向に偏光する光を通過させるように構成される
ものである。この場合、前記２種の偏光部材は、前記パ
ターンの辺に対して４５度に傾いた方向に偏光する光を
通過させるように構成されることが好ましい。また、前
記偏光部材が設けられた光透過部の一部に、透過光の位
相を変化させる位相部材が配置された構成としても良
い。また、本発明の別のフォトマスクは、投影転写すべ
きパターンが基板上に形成されたフォトマスクにおい
て、前記基板の光反射部に、相互に直交する各偏光状態
に変換する少なくとも２種の偏光部材が設けられたもの
である。この場合、前記２種の偏光部材は、前記パター
ンの辺に対して傾いた方向に偏光する光に変換するよう
に構成されることが好ましく、さらには、前記２種の偏
光部材は、前記パターンの辺に対して４５度に傾いた方
向に偏光する光に変換するように構成されることがより
好ましい。また、本発明の露光方法は、上記フォトマス
クを照明する工程と、投影光学系によって前記フォトマ
スクのパターンの像をウエハ面上に結像する工程とを含
むものである。In order to achieve the above object, a photomask according to the present invention is a photomask in which a pattern to be projected and transferred is formed on a transparent substrate. At least two types of polarizing members that convert into respective polarization states orthogonal to each other are repeatedly formed, and the two types of polarizing members are configured to transmit light polarized in a direction inclined with respect to a side of the pattern. Is what is done. In this case, it is preferable that the two types of polarizing members are configured to transmit light polarized in a direction inclined at 45 degrees to the sides of the pattern. Further, a configuration may be adopted in which a phase member for changing the phase of the transmitted light is arranged in a part of the light transmitting section provided with the polarizing member. Further, in another photomask of the present invention, in a photomask in which a pattern to be projected and transferred is formed on a substrate, at least two types of polarized light that are converted into mutually orthogonal polarization states are provided on a light reflecting portion of the substrate. A member is provided. In this case, it is preferable that the two kinds of polarizing members are configured to convert light polarized in a direction inclined with respect to a side of the pattern. It is more preferable to convert to light polarized in a direction inclined at 45 degrees to the side of. The exposure method of the present invention includes a step of illuminating the photomask and a step of forming an image of a pattern of the photomask on a wafer surface by a projection optical system.
【０００９】本発明で用いられる少なくとも２種の偏光
部材は、具体的には、次の１〜３の偏光を生じる部材で
あり、１〜３の何れの場合も生じる偏光同志は相互に直
交する各偏光状態である。 １．振動方向（本明細書でいう振動方向は特に断わらな
いかぎり電気ベクトルの振動方向である）が互いに直交
する２つの直線偏光。 ２．右回転の円偏光と左回転の円偏光。 ３．長軸の方向が直交し、かつ回転方向が反対である２
つの楕円偏光。Specifically, the at least two kinds of polarizing members used in the present invention are members that generate the following 1 to 3 polarized light, and the generated polarized light in any of the cases 1 to 3 is orthogonal to each other. Each polarization state. 1. Two linearly polarized lights whose vibration directions (the vibration direction referred to in the present specification are the vibration directions of the electric vector unless otherwise specified) are orthogonal to each other. 2. Right-handed circularly polarized light and left-handed circularly polarized light. 3. The direction of the long axis is orthogonal and the rotation direction is opposite 2
Elliptically polarized light.
【００１０】[0010]
【作用】一般的に用いられる露光装置においては、フォ
トマスクが透過照明されることにより、フオトマスクに
形成されたパターンに応じた回折光が発生し、発生した
回折光が投影光学系によって再び像面上に集められてパ
ターンの像が形成される。この際、高い次数の回折光ま
で投影光学系に取り込まれる程、得られる像の原図に対
する忠実度が良くなる。従って、回折角が小さければ、
開口数（ＮＡ）の小さい露光装置でもパターンの解像が
可能となる。換言すれば、同じ開口数（ＮＡ）の露光装
置を用いるとすれば、回折角を小さくできるフォトマス
ク程、更に細かいパターンまで解像できるという事にな
る。In a generally used exposure apparatus, when a photomask is transmitted and illuminated, diffracted light corresponding to a pattern formed on a photomask is generated, and the generated diffracted light is again projected onto an image plane by a projection optical system. Collected on top to form an image of the pattern. At this time, the higher the order of the diffracted light is taken into the projection optical system, the better the fidelity of the obtained image to the original drawing. Therefore, if the diffraction angle is small,
A pattern can be resolved even with an exposure apparatus having a small numerical aperture (NA). In other words, if an exposure apparatus having the same numerical aperture (NA) is used, a finer pattern can be resolved with a photomask having a smaller diffraction angle.
【００１１】ところで、波動光学の分野で周知のよう
に、パターンの基本周期をＰとすると、回折角θは、 Ｐsin θ＝ｎλ（ｎ＝０，±１，±２，…） …(1) を満たす方向に出る。ここで、λは波長、ｎは回折光の
次数を表わす。By the way, as is well known in the field of wave optics, assuming that the basic period of a pattern is P, the diffraction angle θ is Psin θ = nλ (n = 0, ± 1, ± 2,...) (1) Get out in the direction to meet. Here, λ represents the wavelength, and n represents the order of the diffracted light.
【００１２】(1) 式から容易に解る様に、周期Ｐが大き
い程、回折角θは小さくなる。先に説明した図３と図４
を比較すると、位相シフトマスク（図４）でのラインア
ンドスペースパターンの基本周期Ｐは、位相部材を付加
していない従来のフォトマスク（図３）の基本周期Ｐの
２倍の大きさになっている。このため、図４の位相シフ
トマスクで生じる回折光の回折角は、図３のフォトマス
クに比べて小さくなり、より高い次数の回折光まで投影
光学系に取りこまれることになる。このことが、位相シ
フトマスクを用いることで結像性能の向上が図られる主
たる理由の１つとなっている。As is easily understood from equation (1), the diffraction angle θ decreases as the period P increases. 3 and 4 described above.
Is compared, the basic period P of the line-and-space pattern in the phase shift mask (FIG. 4) is twice as large as the basic period P of the conventional photomask without the phase member (FIG. 3). ing. For this reason, the diffraction angle of the diffracted light generated by the phase shift mask of FIG. 4 is smaller than that of the photomask of FIG. 3, and higher order diffracted light is taken into the projection optical system. This is one of the main reasons that the imaging performance is improved by using the phase shift mask.
【００１３】ここで、露光装置の開口数が非常に大きけ
れば、回折角の大きい回折光まで取りこむことができる
わけであるが、露光装置の開口数はいくらでも大きくで
きるというものではなく、得られる像の焦点深度等を含
む総合的な結像性能を考慮して設定されており、露光装
置の側で解像限界を引き伸すには限界がある。パターン
の微細化が進んで周期Ｐが一定以下になれば、±１次回
折光すら像面に到達しないことになり、解像不能とな
る。Here, if the numerical aperture of the exposure apparatus is very large, it is possible to capture even a diffracted light beam having a large diffraction angle. However, the numerical aperture of the exposure apparatus cannot be increased arbitrarily. Is set in consideration of the overall imaging performance including the depth of focus of the exposure apparatus, and there is a limit in extending the resolution limit on the exposure apparatus side. If the period P becomes smaller than a certain value due to the progress of pattern miniaturization, even ± 1st-order diffracted light will not reach the image plane, making it impossible to resolve.
【００１４】そこで、本発明では、従来利用されていな
かった光の偏光という特質を用いて、パターンの周期Ｐ
を拡大することによって、解像力の向上を図っている。
以下、図３のラインアンドスペースパターンに本発明を
適用した場合（図１参照）を例にとって、本発明の作用
を具体的に説明する。図１において、遮光部１を介して
隣り合う光透過部２ａ，２ｂには、互いに直交する方向
に振動する光を透過させる偏光部材がそれぞれ付加され
ている。図中矢印は、光透過部２ａ，２ｂを透過できる
光の振動方向を示し、ここでは直交する２つの偏光状態
をそれぞれＡ，Ｂと呼ぶことにする。Therefore, in the present invention, the pattern period P
The resolution is improved by enlarging.
Hereinafter, the operation of the present invention will be specifically described with reference to an example in which the present invention is applied to the line and space pattern of FIG. 3 (see FIG. 1). In FIG. 1, a polarizing member that transmits light that vibrates in directions perpendicular to each other is added to the light transmitting portions 2a and 2b adjacent to each other via the light shielding portion 1. Arrows in the figure indicate the vibration directions of light that can pass through the light transmitting portions 2a and 2b, and here, two orthogonal polarization states are referred to as A and B, respectively.
【００１５】一般に、光は２種の直交する偏光状態の和
で表現できるので、偏光Ａ，Ｂについてそれぞれ独立に
考える。まず、偏光Ａに注目すると、光透過部２ａはそ
のまま通過できるが、光透過部２ｂについては透過する
ことができず、光透過部２ｂは偏光Ａにとっては光不透
過部となる。その為、偏光Ａで観測した図１(a) のパタ
ーンの振幅透過率は、図１(b) のＡで示した状態とな
り、一つおきの光透過部２ａでのみ透過率が高くなる。In general, light can be represented by the sum of two orthogonal polarization states, so that the polarizations A and B are considered independently. First, focusing on the polarized light A, the light transmitting portion 2a can pass through as it is, but cannot transmit the light transmitting portion 2b, and the light transmitting portion 2b becomes a light non-transmitting portion for the polarized light A. Therefore, the amplitude transmittance of the pattern of FIG. 1A observed with the polarized light A is in the state indicated by A in FIG. 1B, and the transmittance is increased only in every other light transmitting portion 2a.
【００１６】同様に、偏光Ｂに注目して考えると、光透
過部２ｂは透過できるが、光透過部２ａは偏光Ｂにとっ
ては光不透過部となる。即ち、偏光Ａの場合とは透過で
きる箇所が逆転し、偏光Ｂで観測したパターンの振幅透
過率は、図１(b) のＢで示した状態となる。Similarly, considering the polarized light B, the light transmitting portion 2b can transmit light, but the light transmitting portion 2a becomes a light non-transmitting portion for the polarized light B. That is, the portion that can be transmitted through the polarized light A is reversed, and the amplitude transmittance of the pattern observed with the polarized light B is in the state indicated by B in FIG.
【００１７】これらのことから、２つの直交偏光Ａ，Ｂ
が互いに分離されてフオトマスクを透過する図１場合の
パターンの基本周期Ｐは、光透過部２ｂ（偏光Ａの光不
透過部）−遮光部１−光透過部２ａ（偏光Ｂの光不透過
部）−遮光部１となり、偏光Ａと偏光Ｂの平均状態の光
が従来のフォトマスクを透過する場合（前述した図３の
場合）に比べてパターンの基本周期Ｐが２倍の大きさと
なることがわかる。このことは、同じ開口数の露光装置
を用いたとしても、２つの直交偏光Ａ，Ｂがそれぞれ透
過する偏光部材を付加した図１のフォトマスクを用いる
ことによってより高い解像を得られる事を示している。From these facts, two orthogonally polarized lights A, B
1 are separated from each other and pass through the photomask. The basic period P of the pattern in FIG. 1 is a light transmitting portion 2b (a light non-transmitting portion of polarized light A) -a light shielding portion 1-a light transmitting portion 2a (a light non-transmitting portion of polarized light B). -The light-shielding portion 1 and the basic period P of the pattern is twice as large as that in the case where the light in the average state of the polarized light A and the polarized light B passes through the conventional photomask (the case of FIG. 3 described above). I understand. This means that even if an exposure apparatus having the same numerical aperture is used, a higher resolution can be obtained by using the photomask of FIG. 1 to which a polarizing member through which two orthogonally polarized lights A and B are respectively transmitted is added. Is shown.
【００１８】また、本発明は位相シフトマスクにも適用
でき、偏光部材と位相部材を組み合わせて光透過部に付
加することにより（詳細は後述）、更にパターンの周期
を大きくすることも可能である。The present invention can also be applied to a phase shift mask, and it is possible to further increase the pattern period by combining a polarizing member and a phase member and adding them to a light transmitting portion (details will be described later). .
【００１９】[0019]
実施例１ 本発明の第１実施例を図１を参照して説明する。図にお
いて、露光光に対して透明な基板上には、クロム等から
なる遮光部１が所定のピッチで配列されており、ライン
アンドスペースパターンが形成されいる。遮光部１を介
して隣り合う光透過部２ａ，２ｂには、振動方向が直交
し、かつ、振動方向がパターンの辺に対して４５度に傾
いた方向（理由は後述）にある２つの直線偏光Ａ，Ｂを
透過させる偏光部材がそれぞれ設けられている。この偏
光部材は、遮光パターン形成面側に設けても良いし、遮
光パターンとは反対側に設けても良いものである。Embodiment 1 A first embodiment of the present invention will be described with reference to FIG. In the figure, light shielding portions 1 made of chrome or the like are arranged at a predetermined pitch on a substrate transparent to exposure light, and a line and space pattern is formed. Two straight lines whose vibration directions are orthogonal to each other and whose vibration directions are inclined at 45 degrees with respect to the sides of the pattern (the reason will be described later) are provided on the light transmitting parts 2a and 2b adjacent to each other via the light shielding part 1. Polarizing members for transmitting the polarized lights A and B are provided. The polarizing member may be provided on the light-shielding pattern forming surface side, or may be provided on the side opposite to the light-shielding pattern.
【００２０】かかるフォトマスクにおいては、偏光Ａに
ついては光透過部２ｂが光不透過部となり、偏光Ｂに対
しては光透過部２ａが光不透過部となり、Ａ，Ｂそれぞ
れの偏光の振幅透過率は図１(b) のようになる。即ち、
本実施例におけるパターンの基本周期Ｐは、作用の項で
も説明したように、偏光部材を付加しない場合の２倍と
なり、その分だけ透過光の回折角が小さくなる。これに
より、同じ露光装置を用いたとしても、従来のフォトマ
スクに比べて解像力が向上することになる。In this photomask, the light transmitting portion 2b becomes a light non-transmitting portion for the polarized light A, the light transmitting portion 2a becomes a light non-transmitting portion for the polarized light B, and the amplitude transmission of the polarized light of A and B respectively. The rate is as shown in Fig. 1 (b). That is,
The basic period P of the pattern in this embodiment is twice as large as that in the case where the polarizing member is not added, and the diffraction angle of the transmitted light is reduced by that amount, as described in the section of the operation. As a result, even if the same exposure apparatus is used, the resolution is improved as compared with the conventional photomask.
【００２１】さてここで、本実施例において、偏光Ａと
偏光Ｂの振動方向をパターンの辺に対して４５度に傾い
た方向とした理由について説明する。直線偏光には、電
気ベクトルの振動方向が入射面に対して垂直なＴＥ（tr
ansverse electric ）偏光状態と、磁気ベクトルの振動
方向が入射面に垂直、即ち、電気ベクトルの振動方向が
入射面内にあるＴＭ（transverse magnetic ）偏光状態
があり、フォトマスクに照射される光は、ＴＥ偏光とＴ
Ｍ偏光の平均状態となっている。仮に、光透過部２ａに
ＴＥ偏光（図１(a) のパターンと平行な方向に電気ベク
トルが振動）のみを透過させる偏光部材を設け、光透過
部２ｂにＴＭ偏光（図１(a) のパターンの配列方向に電
気ベクトルが振動）のみを透過させる偏光部材を設けた
とすると、次のような問題がおこる。Now, the reason why the oscillation directions of the polarized light A and the polarized light B in the present embodiment are inclined at 45 degrees with respect to the sides of the pattern will be described. For linearly polarized light, TE (tr
ansverse electric) polarization state and TM (transverse magnetic) polarization state in which the vibration direction of the magnetic vector is perpendicular to the plane of incidence, that is, the vibration direction of the electric vector is in the plane of incidence. TE polarization and T
It is in the average state of M polarized light. For example, a polarizing member that transmits only TE polarized light (an electric vector vibrates in a direction parallel to the pattern of FIG. 1A) is provided in the light transmitting portion 2a, and TM polarized light (FIG. 1A) is provided in the light transmitting portion 2b. If a polarizing member that transmits only the electric vector vibrates in the pattern arrangement direction is provided, the following problem occurs.
【００２２】即ち、フォトマスクが透過照明されると、
フォトマスクからは各次数の回折光が生じ、回折次数の
異なる光は入射面内の異なる光路を通って結像面に到達
することになるが、ＴＥ偏光の場合は回折次数が異なっ
ても電気ベトクルの振動方向が常に入射面に垂直な方向
に揃うことになり、回折光同志の干渉効果が最大とな
る。一方、ＴＭ偏光の場合は、回折角の差に対応して異
なる次数の回折光の電気ベクトルの振動方向がずれるこ
とになり、回折光同志の干渉効果が低下する。That is, when the photomask is illuminated by transmission,
Diffracted light of each order is generated from the photomask, and light having different diffraction orders reaches the imaging plane through different optical paths in the incident surface. The direction of vibration of the vehicle is always aligned with the direction perpendicular to the plane of incidence, and the interference effect between diffracted light beams is maximized. On the other hand, in the case of TM polarized light, the direction of oscillation of the electric vector of the diffracted light of a different order is shifted in accordance with the difference in the diffraction angle, and the interference effect of the diffracted light is reduced.
【００２３】従って、像面においては、ＴＥ偏光が透過
する光透過部２ａに対応する部分の光強度が大きく、そ
れに比べてＴＭ偏光が透過する光透過部２ｂに対応する
部分の光強度が低くなり、一連のラインアンドスペース
パターン内で明部の明るさが異なることになる。本実施
例では、このような明るさの差が生じること回避するた
めに、光透過部２ａ，２ｂで透過させる光の振動方向
を、パターンの辺に対して４５度傾けており、パターン
像の明部ではＴＥ偏光の場合とＴＭ偏光の場合の中間の
光強度が得られる。なお、パターン像の明部の光強度が
均一でなくとも良い場合は、偏光Ａ，Ｂの振動方向は互
いに直交していさえすれば、振動方向自体は特に限定さ
れるものでないことは言うまでもない。Therefore, on the image plane, the light intensity of the portion corresponding to the light transmitting portion 2a through which the TE polarized light is transmitted is large, and the light intensity of the portion corresponding to the light transmitting portion 2b through which the TM polarized light is transmitted is low. That is, the brightness of the bright portion differs in a series of line and space patterns. In the present embodiment, in order to avoid such a difference in brightness, the vibration direction of light transmitted through the light transmitting portions 2a and 2b is inclined by 45 degrees with respect to the sides of the pattern, and In the bright part, an intermediate light intensity between the case of the TE polarized light and the case of the TM polarized light is obtained. In the case where the light intensity of the bright part of the pattern image does not need to be uniform, it goes without saying that the vibration direction itself is not particularly limited as long as the vibration directions of the polarized lights A and B are orthogonal to each other.
【００２４】また、図１の例では直交偏光Ａ，Ｂを与え
る２種類の偏光部材のみを用いているが、本発明のフォ
トマスクに使用する偏光部材は３種類以上であって良
い。パターンの配列方向などが異なる箇所でそれぞれの
パターンに見合った偏光部材を用いることは勿論、１連
のパターン内で３種類以上の偏光部材を用いても良い。Further, in the example of FIG. 1, only two types of polarizing members for providing the orthogonal polarized lights A and B are used, but three or more types of polarizing members may be used for the photomask of the present invention. It is a matter of course that three or more types of polarizing members may be used in a series of patterns, not to mention using a polarizing member suitable for each pattern at a place where the arrangement direction of the patterns is different.
【００２５】実施例２ 次に、本発明と位相シフトマスクを組み合わせた実施例
について、図２を参照して説明する。図２(a) におい
て、透明基板上には、クロム等の遮光部１が所定のピッ
チで配列されてラインアンドスペースパターンが形成さ
れており、遮光部１を介して隣り合う光透過部２ｃ，２
ｄには、振動方向が相互に直交し、かつ、振動方向がパ
ターンの辺に対して４５度に傾いた方向にある２つの直
線偏光Ａ，Ｂを透過させる偏光部材がそれぞれ設けられ
ている。そして、本実施例では、遮光部１を介して隣接
し、それぞれ直交する２つの偏光Ａ，Ｂを透過させる偏
光部材が付加された２つの光透過部２ｃと２ｄを１組と
して、１組おきに透過光の位相をπ変化させる位相部材
が付加されている。Embodiment 2 Next, an embodiment in which the present invention is combined with a phase shift mask will be described with reference to FIG. In FIG. 2A, a light-shielding portion 1 made of chrome or the like is arranged at a predetermined pitch on a transparent substrate to form a line-and-space pattern. 2
At d, polarizing members are provided, each transmitting two linearly polarized lights A and B whose vibration directions are orthogonal to each other and whose vibration directions are inclined at 45 degrees to the sides of the pattern. In the present embodiment, two light transmitting portions 2c and 2d adjacent to each other via the light shielding portion 1 and to which a polarizing member for transmitting two orthogonally polarized light beams A and B are added are set as one set. , A phase member for changing the phase of transmitted light by π is added.
【００２６】このような構成のフォトマスクの振幅透過
率は図２(b) に示されるようになる。まず、偏光Ａは、
光透過部２ｃのみを通過でき、光透過部２ｄは偏光Ａに
とっては光不透明部となり、更に、同じ偏光部材が付加
された光透過部２ｃの中でも最も近い光透過部２ｃ同志
の振幅は反転することになる。偏光Ｂについては、偏光
Ａが透過できる光透過部２ｃが光不透過部となり、偏光
Ａの場合と同様に、最も近い光透過部２ｄ同志の振幅は
反転することになる。The amplitude transmittance of the photomask having such a structure is as shown in FIG. 2 (b). First, polarization A
The light transmitting portion 2c can pass through only the light transmitting portion 2c, the light transmitting portion 2d becomes a light opaque portion for the polarized light A, and the amplitude of the closest light transmitting portion 2c among the light transmitting portions 2c to which the same polarizing member is added is inverted. Will be. As for the polarized light B, the light transmitting portion 2c through which the polarized light A can be transmitted becomes the light non-transmitting portion, and the amplitude of the closest light transmitting portion 2d is inverted as in the case of the polarized light A.
【００２７】従って、図２におけるパターンの基本周期
Ｐは、光透過部２ｄ（位相部材なし）−遮光部１−光透
過部２ｃ（位相部材あり）−遮光部１−光透過部２ｄ
（位相部材あり）−遮光部１−光透過部２ｃ（位相部材
なし）−遮光部１となり、図３の従来例に比べてパター
ンの基本周期Ｐが４倍となる。従って、図２のフォトマ
スクを用いれば、同じ露光装置を用いたとしても、図３
のフォトマスクに比べてずっと微細なパターンまで解像
可能となる。Therefore, the basic period P of the pattern in FIG. 2 is the light transmitting portion 2d (without the phase member), the light shielding portion 1-the light transmitting portion 2c (with the phase member), the light shielding portion 1 and the light transmitting portion 2d.
(With phase member) -light-shielding portion 1-light transmitting portion 2c (without phase member) -light-shielding portion 1, and the basic period P of the pattern is four times that of the conventional example of FIG. Therefore, if the photomask of FIG. 2 is used, even if the same exposure apparatus is used, FIG.
It is possible to resolve a much finer pattern than the photomask described above.
【００２８】ここで、位相部材と偏光部材の組み合わせ
方については、図２の例に限定されるものではないこと
は言うまでもないが、振動方向の直交する光は互いに干
渉しないので、この点を考慮して各部材を配置すること
が望ましい。図２(a) において、偏光Ａと偏光Ｂは干渉
せず、偏光Ａ同志、偏光Ｂ同志が干渉することになるの
で、光透過部２ｃだけ又は光透過部２ｄだけに位相部材
を付加したとすると、同一方向に振動する光同志の位相
は変化しないから、位相部材を付加してもしなくても同
じことになる。Here, it is needless to say that the method of combining the phase member and the polarizing member is not limited to the example shown in FIG. 2, but light beams having orthogonal vibration directions do not interfere with each other. It is desirable to dispose each member. In FIG. 2A, the polarized light A and the polarized light B do not interfere with each other, and the polarized light A and the polarized light B interfere with each other. Therefore, it is assumed that a phase member is added only to the light transmitting portion 2c or only the light transmitting portion 2d. Then, since the phases of the light beams oscillating in the same direction do not change, the same is obtained with or without the addition of the phase member.
【００２９】また、直交する２つの偏光Ａ，Ｂをそれぞ
れ透過させる偏光部材に加えて第３の方向に振動する偏
光Ｃを透過させる偏光部材を付加した場合には、偏光
Ａ，Ｂと偏光Ｃが部分的に干渉することになるので、近
接した光透過部に３種以上の偏光部材を設ける場合には
各偏光の干渉に留意することが望まれる。When a polarizing member that transmits polarized light C that vibrates in the third direction is added to a polarizing member that transmits two orthogonal polarized lights A and B, the polarized light A and the polarized light C In the case where three or more types of polarizing members are provided in the adjacent light transmitting portion, it is desired to pay attention to the interference of each polarized light.
【００３０】位相シフトマスクについては、遮光部を介
して隣合う光透過部の一方に位相シフト部材を付加する
空間周波数変調方式（図４で説明したフオトマスクや特
公昭６２−５０８１１号公報に記載フォトマスク）の
他、厚さの異なる位相部材を設ける多段方式、遮光パタ
ーンの周縁部に位相シフト部材からなる補助パターンを
設ける補助パターン方式、遮光部と光透過部の境界に位
相シフト部材を設けるエッジ強調方式等種々の方式が提
案されているが、本発明は何れの方式の位相シフトマス
クにも適用できるものである。図２の例のように位相部
材と偏光部材を組み合わせて付加する他、回路パターン
によっては、ある領域で位相部材のみを付加し、別の領
域では偏光部材のみを付加するようにしても良い。ま
た、転写すべきパターン像の暗部に対応する箇所に必ず
しも遮光膜を設ける必要はなく、位相シフト部材だけで
パターン形成しても良い。例えば、位相シフト部材を市
松格子状に配置することよって遮光膜を用いなくとも暗
部が得られる。As for the phase shift mask, a spatial frequency modulation method in which a phase shift member is added to one of the adjacent light transmitting portions via a light shielding portion (see the photomask described with reference to FIG. 4 and the photomask disclosed in Japanese Patent Publication No. Sho 62-50811). Mask), a multi-stage method in which phase members having different thicknesses are provided, an auxiliary pattern method in which an auxiliary pattern made of a phase shift member is provided around the periphery of the light shielding pattern, an edge in which a phase shift member is provided at the boundary between the light shielding portion and the light transmitting portion Although various methods such as an emphasis method have been proposed, the present invention can be applied to any type of phase shift mask. In addition to adding a phase member and a polarizing member in combination as in the example of FIG. 2, depending on a circuit pattern, only a phase member may be added in a certain region and only a polarizing member may be added in another region. Further, it is not always necessary to provide a light-shielding film at a portion corresponding to a dark portion of a pattern image to be transferred, and a pattern may be formed only by a phase shift member. For example, by disposing the phase shift members in a checkerboard pattern, a dark portion can be obtained without using a light-shielding film.
【００３１】なお、図１，図２の実施例では、振動方向
が直交する直線偏光に変換する偏光部材を用いる例につ
いて説明したが、本発明における偏光部材は、振動方向
が時間とともに回転する円偏光，楕円偏光を生じる偏光
部材であっても良い。円偏光を利用する場合は、図１，
図２の遮光部を介して隣接する光透過部の一方に右回転
の円偏光を透過する偏光部材を付加し、他方の光透過部
に左回転の円偏光を透過する偏光部材を付加すれば良
い。楕円偏光を利用する場合は、長軸の方向が直交し、
かつ回転方向が反対の楕円偏光を透過させる偏光部材を
それぞれ付加すれば良い。In the embodiments shown in FIGS. 1 and 2, an example is described in which a polarizing member is used which converts linearly polarized light whose vibration direction is orthogonal. However, the polarizing member of the present invention is a circular member whose vibration direction rotates with time. A polarizing member that generates polarized light or elliptically polarized light may be used. When using circularly polarized light, see Figure 1
A polarizing member transmitting right-handed circularly polarized light is added to one of the adjacent light transmitting portions via the light-shielding portion in FIG. 2, and a polarizing member transmitting left-handed circularly polarized light is added to the other light transmitting portion. good. When using elliptically polarized light, the major axis directions are orthogonal,
What is necessary is just to add a polarizing member that transmits elliptically polarized light having the opposite rotation direction.
【００３２】また、上記の説明においては、透過型のフ
ォトマスクについて述べてきたが、透明基板上に反射部
材（反射膜）を設けた反射型マスクについても、反射部
に偏光部材を付加することによって透過型フォトマスク
と同様に解像力を高めることができる。反射型フォトマ
スクは、フォトマスクを落射照明して、反射膜からの反
射光を結像光学系で集めて像を形成するものてあり、光
透過部が像の暗部、反射部が像の明部に対応するので、
上述の透過型フォトマスクの光透過部を反射部、遮光部
を光透過部と置き換えて考えれば良い。In the above description, the transmission type photomask has been described. However, in the case of a reflection type mask in which a reflection member (reflection film) is provided on a transparent substrate, a polarization member is added to the reflection portion. Thus, the resolving power can be increased similarly to the transmission type photomask. A reflective photomask is an apparatus that forms an image by illuminating the photomask with incident light and collecting light reflected from a reflective film by an imaging optical system. The light transmitting portion is a dark portion of the image, and the reflecting portion is a bright image. Because it corresponds to the department,
The light transmitting portion of the above-mentioned transmission type photomask may be replaced with a reflecting portion and the light shielding portion may be replaced with a light transmitting portion.
【００３３】[0033]
【発明の効果】以上の様に本発明のフォトマスクにおい
ては、相互に直交する各偏光状態の光をそれぞれ透過さ
せる少なくとも２種の偏光部材を光透過部に設けている
ので、パターンの基本周期を大きくすることができる。
パターンの周期が大きくなれば、それだけフォトマスク
で生じる回折光の回折角が小さくなり、同じ開口数の露
光装置を用いたとしても、解像力の向上を図ることが可
能となる。また、本発明のフォトマスクは、近年開発さ
れた位相シフトマスクと組み合わせることもでき、従来
不可能であった微細パターンの解像を実現できる。As described above, in the photomask of the present invention, since at least two types of polarizing members for transmitting the lights of the respective polarization states orthogonal to each other are provided in the light transmitting portion, the basic period of the pattern is changed. Can be increased.
As the period of the pattern increases, the diffraction angle of the diffracted light generated by the photomask decreases accordingly, and the resolution can be improved even when an exposure apparatus having the same numerical aperture is used. Further, the photomask of the present invention can be combined with a phase shift mask developed in recent years, and can realize the resolution of a fine pattern which has been impossible in the past.
【図１】(a) は本発明の第１実施例によるフォトマスク
の模式的な平面図、(b) は図１(a) のフォトマスクの振
幅透過率を示す説明図である。1 (a) is a schematic plan view of a photomask according to a first embodiment of the present invention, and FIG. 1 (b) is an explanatory diagram showing the amplitude transmittance of the photomask of FIG. 1 (a).
【図２】(a) は本発明の第２実施例によるフォトマスク
の模式的な平面図、(b) は図２(a) のフォトマスクの振
幅透過率を示す説明図である。FIG. 2 (a) is a schematic plan view of a photomask according to a second embodiment of the present invention, and FIG. 2 (b) is an explanatory diagram showing the amplitude transmittance of the photomask of FIG. 2 (a).
【図３】(a) は従来の一般的なフォトマスクの模式的な
平面図、(b) は図３(a) のフォトマスクの振幅透過率を
示す説明図である。3 (a) is a schematic plan view of a conventional general photomask, and FIG. 3 (b) is an explanatory diagram showing the amplitude transmittance of the photomask of FIG. 3 (a).
【図４】(a) は従来の位相シフトマスクの模式的な平面
図、(b) は図４(a) の位相シフトマスクの振幅透過率を
示す説明図である。4 (a) is a schematic plan view of a conventional phase shift mask, and FIG. 4 (b) is an explanatory diagram showing an amplitude transmittance of the phase shift mask of FIG. 4 (a).
１ 遮光部 ２ａ，２ｂ，２ｃ，２ｄ 偏光部材を付加した光透過部 1 light-shielding part 2a, 2b, 2c, 2d light-transmitting part with added polarizing member
フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G03F 1/00 - 1/16 Continuation of front page (58) Field surveyed (Int.Cl. 7 , DB name) G03F 1/00-1/16
Claims (7)
形成されたフォトマスクにおいて、 前記透明基板の光透過部に、相互に直交する各偏光状態
に変換する少なくとも２種の偏光部材が繰り返し形成さ
れ、 前記２種の偏光部材は、前記パターンの辺に対して傾い
た方向に偏光する光を通過させるように構成されること
を特徴とするフォトマスク。1. A photomask in which a pattern to be projected and transferred is formed on a transparent substrate, wherein at least two types of polarizing members for converting into mutually orthogonal polarization states are repeatedly formed in a light transmitting portion of the transparent substrate. A photomask, wherein the two types of polarizing members are configured to transmit light polarized in a direction inclined with respect to sides of the pattern.
辺に対して４５度に傾いた方向に偏光する光を通過させ
るように構成されることを特徴とする請求項１に記載の
フォトマスク。2. The photo of claim 1, wherein the two types of polarizing members are configured to transmit light polarized in a direction inclined at 45 degrees with respect to a side of the pattern. mask.
部に、透過光の位相を変化させる位相部材が配置された
ことを特徴とする請求項１又は請求項２に記載のフォト
マスク。3. The photomask according to claim 1, wherein a phase member for changing the phase of the transmitted light is disposed at a part of the light transmitting portion provided with the polarizing member. .
されたフォトマスクにおいて、前記基板の光反射部に、
相互に直交する各偏光状態に変換する少なくとも２種の
偏光部材が設けられたことを特徴とするフォトマスク。4. A photomask in which a pattern to be projected and transferred is formed on a substrate, wherein:
A photomask, comprising: at least two types of polarizing members for converting into mutually orthogonal polarization states.
辺に対して傾いた方向に偏光する光に変換するように構
成されることを特徴とする請求項４に記載のフォトマス
ク。5. The photomask according to claim 4, wherein the two kinds of polarizing members are configured to convert the polarized light into light polarized in a direction inclined with respect to a side of the pattern.
辺に対して４５度に傾いた方向に偏光する光に変換する
ように構成されることを特徴とする請求項５に記載のフ
ォトマスク。6. The photo of claim 5, wherein the two types of polarizing members are configured to convert the polarized light into light polarized in a direction inclined at 45 degrees to the sides of the pattern. mask.
載のフォトマスクを照明する工程と、投影光学系によっ
て前記フォトマスクのパターンの像をウエハ面上に結像
する工程とを含むことを特徴とする露光方法。7. A step of illuminating the photomask according to claim 1, 2, 3, 4, 5, or 6, and a step of forming an image of a pattern of the photomask on a wafer surface by a projection optical system. An exposure method comprising:
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16738391A JP3087353B2 (en) | 1991-06-13 | 1991-06-13 | Photomask and exposure method using the same |
| US08/480,360 US5541026A (en) | 1991-06-13 | 1995-06-07 | Exposure apparatus and photo mask |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16738391A JP3087353B2 (en) | 1991-06-13 | 1991-06-13 | Photomask and exposure method using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04366841A JPH04366841A (en) | 1992-12-18 |
| JP3087353B2 true JP3087353B2 (en) | 2000-09-11 |
Family
ID=15848693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16738391A Expired - Lifetime JP3087353B2 (en) | 1991-06-13 | 1991-06-13 | Photomask and exposure method using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3087353B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR0153796B1 (en) * | 1993-09-24 | 1998-11-16 | 사토 후미오 | Exposure apparatus and method |
| JP3958163B2 (en) | 2002-09-19 | 2007-08-15 | キヤノン株式会社 | Exposure method |
| JP5922459B2 (en) * | 2012-03-26 | 2016-05-24 | 株式会社有沢製作所 | Production method of retardation plate |
-
1991
- 1991-06-13 JP JP16738391A patent/JP3087353B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04366841A (en) | 1992-12-18 |
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