JP2008277398A - Extreme ultraviolet exposure mask, and mask blank - Google Patents

Extreme ultraviolet exposure mask, and mask blank Download PDF

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JP2008277398A
JP2008277398A JP2007116758A JP2007116758A JP2008277398A JP 2008277398 A JP2008277398 A JP 2008277398A JP 2007116758 A JP2007116758 A JP 2007116758A JP 2007116758 A JP2007116758 A JP 2007116758A JP 2008277398 A JP2008277398 A JP 2008277398A
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film
capping
extreme ultraviolet
mask
euv
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JP5194547B2 (en
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Tadashi Matsuo
正 松尾
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Toppan Inc
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an extreme ultraviolet (EUV) exposure mask that is provided at least with a multilayer film 2 formed on a substrate 1, a capping film 3 on the multilayer film 2 to protect the multilayer film 2 and an absorption film 5 formed like a pattern, and that a variance of EUV reflection factor can be suppressed even if the capping film 3 varies in film thickness when forming the capping film 3 or after etching a buffer film 4 immediate above the capping film 3 or the absorption film 5, and to provide a blank for manufacturing the same. <P>SOLUTION: The reflection factor of a part comprised of the multilayer film 2 and the capping film 3 to the extreme ultraviolet ray is within a change quantity of 1% for the changing range of thickness between 2 nm and 4 nm in the capping film 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は、半導体製造プロセス中の、波長１０〜１５ｎｍ程度のいわゆる極端紫外線（Ｅｘｔｒｅｍｅ Ｕｌｔｒａ Ｖｉｏｌｅｔ、以下ＥＵＶと略記）を用いたフォトリソグラフィ工程で使用される、極端紫外線露光用マスク（以下、ＥＵＶマスク）、及びそのマスクを作製するためのマスクブランクに関するものである。   The present invention relates to an extreme ultraviolet exposure mask (hereinafter referred to as EUV mask) used in a photolithography process using so-called extreme ultraviolet (hereinafter referred to as EUV) having a wavelength of about 10 to 15 nm during a semiconductor manufacturing process. ), And a mask blank for producing the mask.

半導体集積回路の微細化は年々進んでおり、それに伴いフォトリソグラフィ技術に使用される光もその短波長化が進んでいる。近況としては、これまで光源として使用されてきたＫｒＦエキシマレーザー（波長２４８ｎｍ）からＡｒＦエキシマレーザー（波長１９３ｎｍ）に移行しつつある。また、ＡｒＦエキシマレーザーを使用する液浸露光法の研究が近年活発に行われており、５０ｎｍ以下の線幅を目標とする動きもある。   The miniaturization of semiconductor integrated circuits is progressing year by year, and accordingly, the light used in photolithography technology is also being shortened. As a recent trend, a KrF excimer laser (wavelength 248 nm), which has been used as a light source, has been shifted to an ArF excimer laser (wavelength 193 nm). In recent years, an immersion exposure method using an ArF excimer laser has been actively researched, and there is a movement aiming at a line width of 50 nm or less.

ＡｒＦエキシマレーザーを使用する液浸露光法もその研究が進んでいるとはいえ、その実現可能性は不鮮明である。このような背景から、エキシマレーザーよりも波長が一桁以上短い（１０〜１５ｎｍ）ＥＵＶ光を用いた、ＥＵＶリソグラフィーの研究開発が進められている。   Although the immersion exposure method using an ArF excimer laser has been studied, its feasibility is unclear. Against this background, research and development of EUV lithography using EUV light whose wavelength is one or more orders of magnitude shorter (10 to 15 nm) than that of excimer lasers is in progress.

ＥＵＶ露光では、上述のように波長が短いため、物質の屈折率がほとんど真空の値に近く、材料間の光吸収の差も小さい。このため、ＥＵＶ波長領域では従来の透過型の屈折光学系が作れず、反射光学系となり、マスクも反射型マスクとなる。これまで開発されてきた一般的なＥＵＶマスクは、Ｓｉウェハーやガラス基板上に、例えばＭｏとＳｉからなる２層膜を４０対ほど積層した多層膜、および多層膜を保護するキャッピング膜を高反射領域とし、その上に低反射領域として吸収膜および緩衝膜のパターンを形成した構造であった。キャッピング膜は、ＥＵＶ反射率を低下させないために、ＥＵＶ光に対して透明である必要があり、通常Ｓｉ膜や薄いＲｕ膜や、その化合物膜、Ｚｒの化合物膜などが使われる。また緩衝膜は、吸収膜のパターニングや欠陥修正の際に、キャッピング膜や多層膜へのダメージを軽減する機能を持つ必要がある。   In EUV exposure, since the wavelength is short as described above, the refractive index of a substance is almost close to the value of vacuum, and the difference in light absorption between materials is also small. For this reason, in the EUV wavelength region, a conventional transmissive refractive optical system cannot be formed, and a reflective optical system is formed, and the mask is also a reflective mask. Conventional EUV masks that have been developed so far are highly reflective of a multilayer film in which about 40 pairs of two-layer films made of, for example, Mo and Si are laminated on a Si wafer or glass substrate, and a capping film that protects the multilayer film. In this structure, an absorption film and a buffer film pattern are formed as a low reflection region on the region. The capping film needs to be transparent to EUV light so as not to reduce the EUV reflectivity, and a Si film, a thin Ru film, a compound film thereof, a Zr compound film, or the like is usually used. Further, the buffer film needs to have a function of reducing damage to the capping film and the multilayer film when the absorption film is patterned and defects are corrected.

一方、低反射領域を形成するために主要な機能を有するのは、ＥＵＶ光を吸収する吸収膜である。吸収膜部は、通常、パターン欠陥検査時のコントラストを確保するために、欠陥検査光である遠紫外線光に対して低反射率となるよう、遠紫外線光に対して透明性の膜が上層に形成される。一方、ＥＵＶ光を吸収するという、主要な機能を有するのは、吸収膜の中でも上層吸収膜を除いた下層吸収膜の部分である。このように、吸収膜は２層以上の積層構造からなる場合もあるが、本発明の目的と本質的な関係はないので、以下、吸収膜は単層として論じ、単に吸収膜と記載する。   On the other hand, an absorption film that absorbs EUV light has a main function for forming the low reflection region. In order to ensure the contrast at the time of pattern defect inspection, the absorption film portion is usually a film transparent to far ultraviolet light so that it has a low reflectance with respect to far ultraviolet light that is defect inspection light. It is formed. On the other hand, the lower absorption film portion excluding the upper absorption film has the main function of absorbing EUV light. As described above, the absorption film may have a laminated structure of two or more layers. However, since there is no essential relationship with the object of the present invention, the absorption film will be discussed below as a single layer and simply referred to as an absorption film.

また、構造によっては、キャッピング膜に緩衝膜として必要な機能を持たせ、キャッピング膜と緩衝膜を一体化して兼用膜とし、１層の膜で構成する場合もある。本発明では、特にことわらない限り、兼用膜もキャッピング膜の一種として論じる。   Further, depending on the structure, the capping film may have a necessary function as a buffer film, and the capping film and the buffer film may be integrated to form a dual-layer film, which may be a single-layer film. In the present invention, unless otherwise specified, the dual-purpose film is also discussed as a kind of capping film.

以下に公知の文献を記す。
特開２００３−３１８１０４号公報 Known documents are described below.
JP 2003-318104 A

前記のように、キャッピング膜は、ＥＵＶ反射率を低下させないために、ＥＵＶ光に対して透明である必要があるが、安定したＥＵＶ露光を行うには、マスク面内および各マスク間でＥＵＶ反射率が変動しないことが重要である。しかるに、ＥＵＶ反射率は、キャッピング膜の膜厚のばらつきによって敏感に変動する。キャッピング膜の膜厚ばらつきを生むものは、ひとつにはキャピッピング膜成膜時のばらつきであり、もうひとつは、キャッピング膜の直上にある膜をエッチング等で剥離するときのばらつきである。すなわち、緩衝膜がある構造では、緩衝膜をエッチングし、オーバーエッチングにするとき、兼用膜の場合は吸収膜をエッチングし、さらにオーバーエッチングするときに、キャッピング膜がエッチングされる量のばらつきである。このようなキャッピング膜厚のばらつきによるＥＵＶ反射率の変動を抑えるには、仮にキャッピング膜厚が変化しても、ＥＵＶ反射率の変動が小さいマスク構造とする必要がある。   As described above, the capping film needs to be transparent to EUV light so as not to decrease the EUV reflectance. However, in order to perform stable EUV exposure, EUV reflection is performed within the mask surface and between each mask. It is important that the rate does not fluctuate. However, the EUV reflectance varies sensitively due to variations in the thickness of the capping film. One of the variations in the thickness of the capping film is a variation in the formation of the capping film, and the other is a variation in peeling the film immediately above the capping film by etching or the like. That is, in the structure with the buffer film, when the buffer film is etched and overetched, in the case of the dual-purpose film, the absorption film is etched, and when the overetching is performed, the amount of the capping film etched is varied. . In order to suppress the fluctuation of the EUV reflectance due to such a variation in the capping film thickness, it is necessary to provide a mask structure in which the fluctuation of the EUV reflectance is small even if the capping film thickness changes.

また、通常Ｓｉ膜をキャッピング膜とする場合は、多層膜の最上層のＳｉ膜を、多層膜を構成するときの約４．２ｎｍではなく、１１ｎｍとして、キャッピング膜とすることが多いが、Ｓｉの特性上の理由や、膜厚が厚いことによって、マスク製造中や、使用中の長期間にわたり酸化が進行し、次第にＥＵＶ反射率が低下していく、という問題があった。   In addition, when the Si film is usually used as a capping film, the uppermost Si film of the multilayer film is often set to 11 nm instead of about 4.2 nm when forming the multilayer film. Due to the above characteristics and the thick film thickness, there is a problem that oxidation proceeds for a long period of time during mask manufacture and use, and the EUV reflectance gradually decreases.

本発明は、かかる課題に対する対策を提供するものであり、キャッピング膜の成膜時や、直上の緩衝膜、または吸収膜のエッチング後に、キャピッピング膜の膜厚にばらつきが生じてもＥＵＶ反射率の変動が小さいＥＵＶ露光用マスク、及びそれを作製するためのブランクを提供する。   The present invention provides a countermeasure against such a problem. Even when the thickness of the capping film varies after the capping film is formed, or after etching of the buffer film or absorption film directly above, the EUV reflectance is improved. The present invention provides an EUV exposure mask with a small fluctuation and a blank for producing the same.

本願発明は係る課題に鑑みなされたもので、請求項１の発明は、基板上に形成された多層膜と、前記多層膜上にあり、前記多層膜を保護するキャッピング膜と、パターン状に形成された吸収膜を少なくとも具備する極端紫外線露光用マスクにおいて、前記多層膜と前記キャッピング膜からなる部分の極端紫外線に対する反射率が、前記キャッピング膜の２ｎｍから４ｎｍの範囲の厚さの変化に対して、１％以内の変化量であることを特徴とする極端紫外線露光用マスクとしたものである。   The present invention has been made in view of the above problems, and the invention of claim 1 is formed in a pattern, a multilayer film formed on a substrate, a capping film on the multilayer film, and protecting the multilayer film. In the extreme ultraviolet exposure mask having at least the absorbed film, the reflectance of the portion composed of the multilayer film and the capping film with respect to the extreme ultraviolet is changed with respect to the thickness change of the capping film in the range of 2 nm to 4 nm. The extreme ultraviolet exposure mask is characterized in that the amount of change is within 1%.

本願の請求項２の発明は、前記多層膜はＭｏとＳｉを交互に積層した多層膜であり、キャッピング膜の直下にある膜がＳｉであることを特徴とする請求項１に記載の極端紫外線露光用マスクとしたものである。   The invention according to claim 2 of the present application is characterized in that the multilayer film is a multilayer film in which Mo and Si are alternately laminated, and the film immediately below the capping film is Si. This is an exposure mask.

本願の請求項３の発明は、前記多層膜の、キャッピング膜の直下にあるＳｉの膜厚は、Ｍｏと交互に積層する場合のＳｉの厚さとは異なることを特徴とする請求項２に記載の極端紫外線露光用マスクとしたものである。   The invention of claim 3 of the present application is characterized in that the thickness of Si in the multilayer film immediately below the capping film is different from the thickness of Si when alternately laminated with Mo. The extreme ultraviolet exposure mask.

本願の請求項４の発明は、前記請求項１に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランクとしたものである。   The invention of claim 4 of the present application is an extreme ultraviolet exposure mask blank for producing the extreme ultraviolet exposure mask of claim 1.

本願の請求項５の発明は、前記請求項２に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランクとしたものである。   The invention of claim 5 of the present application is an extreme ultraviolet exposure mask blank for manufacturing the extreme ultraviolet exposure mask of claim 2.

本願の請求項６の発明は、前記請求項３に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランクとしたものである。   The invention of claim 6 of the present application is an extreme ultraviolet exposure mask blank for manufacturing the extreme ultraviolet exposure mask of claim 3.

本発明の請求項７の発明は、キャッピング膜がＺｒＳｉ2又はＺｒＳｉＯで形成され、キャッピング膜直下のＳｉ膜厚が、多層膜の１周期の４分の１倍もしくは４分の５倍であることを特徴とする請求項２に記載の極端紫外線露光用マスクとしたものである。 According to the seventh aspect of the present invention, the capping film is formed of ZrSi 2 or ZrSiO, and the Si film thickness immediately below the capping film is 1/4 or 5/4 times of one cycle of the multilayer film. The extreme ultraviolet exposure mask according to claim 2, wherein:

本発明の請求項８の発明は、キャッピング膜がＲｕで形成され、キャッピング膜直下のＳｉ膜厚が、０を含めた多層膜の１周期分の整数倍から、それに加えて多層膜の１周期分の４分の１倍までの領域を除いた値であることを特徴とする請求項２に記載の極端紫外線露光用マスクとしたものである。   In the invention according to claim 8 of the present invention, the capping film is made of Ru, and the Si film thickness immediately below the capping film is an integral multiple of one period of the multilayer film including 0, in addition to one period of the multilayer film. 3. The extreme ultraviolet exposure mask according to claim 2, wherein the mask is a value excluding an area of up to a quarter of a minute.

本発明は、前述のような構成をしており、キャッピング膜の成膜時や、直上の緩衝膜のエッチング後や、キャッピング膜が緩衝膜との兼用膜である場合の吸収膜のエッチング後に、キャピッピング膜の膜厚にばらつきが生じてもＥＵＶ反射率の変動が小さい。従って、ＥＵＶマスク製造時のマスクごとのＥＵＶ反射率や、１枚のＥＵＶマスク面内のＥＵＶ反射率が安定しており、ＥＵＶマスク製造の収率を上げることができる。また、ＥＵＶマスク使用期間に洗浄を行って、キャッピング膜膜厚がわずかに減少しても、ＥＵＶ反射率の変化がきわめて小さく抑えられるので、長期間にわたり同じＥＵＶマスクを使用することができる。   The present invention has the above-described configuration, after the capping film is formed, after the etching of the buffer film immediately above, or after the absorption film is etched in the case where the capping film is a dual-purpose film with the buffer film, Even if the thickness of the capping film varies, the variation in the EUV reflectance is small. Therefore, the EUV reflectivity for each mask at the time of manufacturing the EUV mask and the EUV reflectivity within the surface of one EUV mask are stable, and the EUV mask manufacturing yield can be increased. Further, even if the capping film thickness is slightly decreased by performing cleaning during the EUV mask usage period, the change in EUV reflectance can be suppressed to be extremely small, so that the same EUV mask can be used over a long period of time.

以下本発明を実施するための形態について説明する。   Hereinafter, modes for carrying out the present invention will be described.

本発明のＥＵＶ露光用マスク及びマスクブランクは、吸収膜の材料および構成については、特に制限はない。多層膜の材料についても特に制限はないが、好ましくは、通常ＥＵＶマスクに用いられるＭｏとＳｉの交互積層膜とする。また、前記のように緩衝膜はあっってもなくてもよい。さらにキャッピング膜としては、通常は前記のように、Ｓｉ膜や薄いＲｕ膜や、その化合物膜、Ｚｒの化合物膜などが使われるが、本発明においてはこの内Ｓｉ膜を対象外とする。その理由は、前記のように、Ｓｉキャッピングの場合は継続的な酸化の進行によりＥＵＶ反射率が漸次的に低下する、ということと、その直下が多層膜を構成するＭｏ膜であるので、本発明で用いる「キャッピング膜直下のＳｉ膜」が存在しない、若しくはキャッピング膜と区別ができない、ことによる。   The EUV exposure mask and mask blank of the present invention are not particularly limited with respect to the material and configuration of the absorption film. The material of the multilayer film is not particularly limited, but is preferably an alternately laminated film of Mo and Si usually used for an EUV mask. Further, as described above, the buffer film may or may not be provided. Further, as described above, an Si film, a thin Ru film, a compound film thereof, a compound film of Zr, or the like is usually used as the capping film. However, in the present invention, this Si film is excluded. The reason for this is that, as described above, in the case of Si capping, the EUV reflectivity gradually decreases due to the continuous oxidation, and immediately below it is a Mo film that constitutes a multilayer film. This is because the “Si film directly under the capping film” used in the invention does not exist or cannot be distinguished from the capping film.

図１、図２は本発明におけるＥＵＶマスクの断面構造図を示している。図１は緩衝膜が存在する場合、図２は、キャッピング膜が緩衝膜も兼用する場合である。   1 and 2 are sectional structural views of an EUV mask according to the present invention. FIG. 1 shows a case where a buffer film is present, and FIG. 2 shows a case where the capping film also serves as a buffer film.

図１、図２において、キャッピング膜３の直下には、多層膜２の最上層としてのＳｉ膜２ｃがある。さらに多層膜最上Ｓｉ膜を除いた、交互に積層する多層膜部分の材料は、好ましくはＭｏ膜とＳｉ膜である。さらに好ましくは、交互に積層する多層膜部分のＭｏ膜の膜厚は約２．８ｎｍであり、同じくＳｉ膜の膜厚は約４．２ｎｍである。   1 and 2, immediately below the capping film 3, there is a Si film 2 c as the uppermost layer of the multilayer film 2. Further, the material of the multilayer film portions to be alternately stacked excluding the uppermost Si film of the multilayer film is preferably a Mo film and a Si film. More preferably, the thickness of the Mo film in the multilayer film portion that is alternately laminated is about 2.8 nm, and the thickness of the Si film is also about 4.2 nm.

ここで、図１、あるいは図２のような構成において、多層膜２とキャッピング膜３部からなる高反射部のＥＵＶ反射率が、キャッピング膜３材料とその厚さ、及びキャッピング膜直下にあるＳｉ膜２ｃの膜厚によって、どのように変化するか、を計算した結果を図３（ａ）〜（ｄ）、図４（ｅ）〜（ｈ）に示す。キャッピング膜３としては、Ｒｕ、ＺｒＳｉ2、ＺｒＳｉＯを検討した。キャッピング膜３直下のＳｉ膜２ｃ厚をパラメータとして、キャッピング膜厚を横軸とし、ＥＵＶ反射率を計算している。図３、４を見ると、同じキャッピング材料で同じ膜厚であっても、ＥＵＶ反射率はキャッピング膜３直下のＳｉ膜２ｃ厚によって変わってくることが分る。 Here, in the configuration as shown in FIG. 1 or FIG. 2, the EUV reflectivity of the high reflection portion composed of the multilayer film 2 and the capping film 3 portion is the Si capping film 3 material, its thickness, and the Si directly below the capping film. FIGS. 3A to 3D and 4E to 4H show the results of calculating how the film 2c changes depending on the film thickness. As the capping film 3, Ru, ZrSi 2 and ZrSiO were examined. The EUV reflectance is calculated using the thickness of the Si film 2c immediately below the capping film 3 as a parameter and the capping film thickness as the horizontal axis. 3 and 4, it can be seen that the EUV reflectivity varies depending on the thickness of the Si film 2c immediately below the capping film 3 even if the same capping material and the same film thickness are used.

さらに、総じて、どの場合もキャッピング膜膜厚は薄い方がＥＵＶ反射率は高くなることが分る。しかし、注目すべきは、その関係は直線的ではない、ということである。すなわち、キャッピング膜厚の変化に対して、ＥＵＶ反射率がほとんど変化しない、若しくは変化量が小さい領域が存在し、その領域がキャッピング膜厚のどの領域にできるか、はキ
ャッピング膜直下のＳｉ膜厚に依存している。 Furthermore, it can be seen that, in all cases, the EUV reflectance increases as the capping film thickness decreases. However, it should be noted that the relationship is not linear. That is, there is a region where the EUV reflectivity hardly changes or the amount of change is small with respect to the change in the capping film thickness, and the region of the capping film thickness that can be made depends on the Si film thickness immediately below the capping film. Depends on.

以上をまとめると、ＥＵＶ反射率が比較的高く、しかもキャッピング膜厚に対して変化しにくく安定するようにするには、キャッピング膜厚の薄い領域に、変化しにくい、ＥＵＶ反射率がフラットな領域をつくる必要があり、そのためにはキャッピング膜直下のＳｉ膜厚をうまく選ぶ必要がある、ということになる。   In summary, in order to make the EUV reflectance relatively high and hardly change with respect to the capping film thickness, the EUV reflectance is flat and the area where the EUV reflectance is flat is difficult to change. Therefore, it is necessary to select a Si film thickness just below the capping film.

以上の観点から図３、４を見ると、キャッピング膜がＺｒＳｉ2とＺｒＳｉＯにおいては、キャッピング膜直下のＳｉ膜厚が、多層膜の１周期、すなわち
Ｍｏ膜厚（２．８ｎｍ）＋Ｓｉ膜厚（４．２ｎｍ）＝７．０ｎｍ
の４分の１倍（図３（ｂ））、若しくは４分の５倍（図４（ｇ））のときに、キャッピング膜厚がほぼ２ｎｍから５ｎｍの薄い領域に反射率が変化しにくい領域が出来ていることが分る。 3 and 4 from the above viewpoint, when the capping film is ZrSi 2 and ZrSiO, the Si film thickness immediately below the capping film is one period of the multilayer film, that is, Mo film thickness (2.8 nm) + Si film thickness ( 4.2 nm) = 7.0 nm
Region where the reflectivity is less likely to change to a thin region with a capping film thickness of approximately 2 nm to 5 nm at a quarter of that (Fig. 3 (b)) or 5/4 (Fig. 4 (g)). You can see that

また、Ｒｕの場合は、ＺｒＳｉ2やＺｒＳｉＯの場合とは逆に、キャッピング膜直下のＳｉ膜厚が０（キャッピング膜直下はＭｏ膜になっている＝図３（ａ））を含めた多層膜の１周期分（７．０ｎｍ）の整数倍（図４（ｅ））から、それに加えて多層膜の１周期分の４分の１までの領域（図３（ｂ）、図４（ｇ））では、Ｒｕ膜厚が薄い領域でＥＵＶ反射率が急激に低下するため、そのようなキャッピング膜直下のＳｉ膜厚を避けねばならないことが分る。 Further, in the case of Ru, in contrast to the case of ZrSi 2 or ZrSiO, the Si film thickness immediately below the capping film is 0 (the Mo film is directly below the capping film = FIG. 3A). The region from an integral multiple of one cycle (7.0 nm) (FIG. 4E) to a quarter of one cycle of the multilayer film (FIGS. 3B and 4G) ), The EUV reflectivity rapidly decreases in a region where the Ru film thickness is thin, and it is understood that such a Si film thickness directly under the capping film must be avoided.

本発明に関わるキャッピング膜直下のＳｉ膜厚の選定を用いて、本発明のＥＵＶマスクブランク、およびＥＵＶマスクを作製した。まず、ＭｏとＳｉからなる４０対の多層膜をイオンビームスパッタリング法により、Ｍｏ膜厚２．８ｎｍ、Ｓｉ膜厚４．２ｎｍで交互に成膜して作製した。その際、最上のＳｉ膜厚は、周期厚７．０ｎｍの略４分の１である１．８ｎｍとした。次にその上に、マグネトロンスパッタリング法により、キャッピング膜としてＺｒＳｉ2膜を７ｎｍ成膜した。ここで図３（ｂ）ＥＵＶ反射率が安定している４ｎｍよりも厚い７ｎｍにしたのは、緩衝膜のオーバーエッチングにより、キャッピング膜が２〜３ｎｍ薄くなるであろうことを想定したためである。引き続き、キャッピング膜の上に緩衝膜としてクロム膜を１０ｎｍ成膜した。しかる後に、マグネトロンスパッタリング法により、吸収膜として、窒化タンタル膜を７００Ａ成膜し、さらにその上に、欠陥検査光に対する反射防止膜として酸素とタンタルを主成分とする膜を１５０Ａ成膜して、本発明のＥＵＶ露光用マスクブランクを作製した。 The EUV mask blank and EUV mask of the present invention were produced using selection of the Si film thickness directly under the capping film according to the present invention. First, 40 pairs of multilayer films made of Mo and Si were alternately formed by an ion beam sputtering method with a Mo film thickness of 2.8 nm and a Si film thickness of 4.2 nm. At that time, the uppermost Si film thickness was set to 1.8 nm, which is approximately a quarter of the periodic thickness 7.0 nm. Next, a 7 nm thick ZrSi 2 film was formed thereon as a capping film by magnetron sputtering. Here, the reason why the thickness of 7 nm, which is thicker than 4 nm where the EUV reflectance is stable in FIG. 3B, is that it is assumed that the capping film will be thinner by 2 to 3 nm due to overetching of the buffer film. Subsequently, a chromium film having a thickness of 10 nm was formed as a buffer film on the capping film. Thereafter, a magnetron sputtering method is used to form a 700 A tantalum nitride film as an absorption film, and further, a 150 A film mainly composed of oxygen and tantalum is formed thereon as an antireflection film for defect inspection light. The mask blank for EUV exposure of this invention was produced.

次に、前記本発明のＥＵＶマスクブランクの吸収膜の上に電子線レジストを塗布し、電子線描画法によりレジストパターンを形成した。このレジストパターンをマスクとし、フッ素系ガスによる反応性イオンエッチングによりＡＲ膜、および吸収膜のパターニングを行い、その後レジストを剥離した。その後、欠陥検査および欠陥修正を行った後、緩衝膜を塩素系ガスに酸素を添加したエッチングにより剥離した。このようにして、本願のＥＵＶ露光用マスクを作製した。   Next, an electron beam resist was applied on the absorption film of the EUV mask blank of the present invention, and a resist pattern was formed by an electron beam drawing method. Using this resist pattern as a mask, the AR film and the absorption film were patterned by reactive ion etching using a fluorine-based gas, and then the resist was peeled off. Then, after performing defect inspection and defect correction, the buffer film was peeled off by etching with oxygen added to chlorine-based gas. Thus, the EUV exposure mask of the present application was produced.

作製したＥＵＶ露光用マスクにおいて、吸収膜と緩衝膜が除去された高反射率部のＥＵＶ反射率を測定したところ、６インチ角基板の１４０ｍｍｘ１４０ｍｍ領域内において、６３．４％から６３．６％であり、平均値、均一性ともに良好であった。   In the produced EUV exposure mask, the EUV reflectivity of the high reflectivity portion from which the absorption film and the buffer film were removed was measured, and it was 63.4% to 63.6% in the 140 mm × 140 mm region of the 6-inch square substrate. Yes, both average value and uniformity were good.

さらに、上記のＥＵＶマスクを３か月使用し、途中で５回の酸およびアルカリ系洗浄液による洗浄を行った後、ＥＵＶ反射を測定したところ、６インチ角基板の１４０ｍｍｘ１４０ｍｍ領域内において、６３．５％から６３．７％であり、経時安定性も優れていることが分った。     Further, the EUV mask was used for 3 months, and after cleaning with acid and alkaline cleaning liquids 5 times in the middle, the EUV reflection was measured. As a result, 63.5 mm in a 140 mm × 140 mm region of the 6 inch square substrate % To 63.7%, and it was found that the stability over time was excellent.

本発明のＥＵＶマスクの断面構造を示す模式図である。It is a schematic diagram which shows the cross-sectional structure of the EUV mask of this invention. 本発明の別のＥＵＶマスクの断面構造を示す模式図である。It is a schematic diagram which shows the cross-section of another EUV mask of this invention. ＥＵＶマスクのＥＵＶ反射率を、キャッピング膜材料とその膜厚、およびキャッピング膜直下のＳｉ膜厚に対して計算した特性図である。It is the characteristic view which calculated the EUV reflectance of the EUV mask with respect to the capping film material, its film thickness, and the Si film thickness directly under the capping film. ＥＵＶマスクのＥＵＶ反射率を、キャッピング膜材料とその膜厚、およびキャッピング膜直下のＳｉ膜厚に対して計算した別の特性図である。It is another characteristic figure which calculated the EUV reflectance of the EUV mask with respect to the capping film material, its film thickness, and the Si film thickness directly under the capping film.

符号の説明Explanation of symbols

１・・・・基板
２・・・・多層膜
２ａ・・・Ｍｏ膜
２ｂ・・・Ｓｉ膜
２ｃ・・・多層膜最上Ｓｉ膜
３・・・・キャッピング膜
４・・・・緩衝膜
５・・・・吸収膜パターン
６・・・・入射ＥＵＶ光
７・・・・反射ＥＵＶ光（反射率Ｒ） DESCRIPTION OF SYMBOLS 1 .... Substrate 2 .... Multilayer film 2a ... Mo film 2b ... Si film 2c ... Multilayer top Si film 3 .... Capping film 4 .... Buffer film 5. ... Absorbing film pattern 6 ... Incident EUV light 7 ... Reflected EUV light (reflectance R)

Claims (8)

基板上に形成された多層膜と、前記多層膜上にあり、前記多層膜を保護するキャッピング膜と、パターン状に形成された吸収膜を少なくとも具備する極端紫外線露光用マスクにおいて、前記多層膜と前記キャッピング膜からなる部分の極端紫外線に対する反射率が、前記キャッピング膜の２ｎｍから４ｎｍの範囲の厚さの変化に対して、１％以内の変化量であることを特徴とする極端紫外線露光用マスク。   A multilayer film formed on a substrate, a capping film on the multilayer film for protecting the multilayer film, and an extreme ultraviolet exposure mask comprising at least an absorption film formed in a pattern. A mask for extreme ultraviolet exposure, wherein a reflectance of the portion made of the capping film with respect to extreme ultraviolet light is a variation within 1% with respect to a change in thickness of the capping film in a range of 2 nm to 4 nm. . 前記多層膜はＭｏとＳｉを交互に積層した多層膜であり、キャッピング膜の直下にある膜がＳｉであることを特徴とする請求項１に記載の極端紫外線露光用マスク。   2. The extreme ultraviolet exposure mask according to claim 1, wherein the multilayer film is a multilayer film in which Mo and Si are alternately laminated, and the film immediately below the capping film is Si. 前記多層膜の、キャッピング膜の直下にあるＳｉの膜厚は、Ｍｏと交互に積層する場合のＳｉの厚さとは異なることを特徴とする請求項２に記載の極端紫外線露光用マスク。   3. The extreme ultraviolet exposure mask according to claim 2, wherein the thickness of Si in the multilayer film immediately below the capping film is different from the thickness of Si when alternately laminated with Mo. 4. 請求項１に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランク。   A mask blank for extreme ultraviolet exposure for producing the mask for extreme ultraviolet exposure according to claim 1. 請求項２に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランク。   An extreme ultraviolet exposure mask blank for producing the extreme ultraviolet exposure mask according to claim 2. 請求項３に記載の極端紫外線露光用マスクを製造するための極端紫外線露光用マスクブランク。   A mask blank for extreme ultraviolet exposure for producing the mask for extreme ultraviolet exposure according to claim 3. キャッピング膜がＺｒＳｉ2又はＺｒＳｉＯで形成され、キャッピング膜直下のＳｉ膜厚が、多層膜の１周期の４分の１倍もしくは４分の５倍であることを特徴とする請求項２に記載の極端紫外線露光用マスク。 The capping film is formed of ZrSi 2 or ZrSiO, and the Si film thickness immediately below the capping film is 1/4 or 5/4 times of one cycle of the multilayer film. Mask for extreme ultraviolet exposure. キャッピング膜がＲｕで形成され、キャッピング膜直下のＳｉ膜厚が、０を含めた多層膜の１周期分の整数倍から、それに加えて多層膜の１周期分の４分の１倍までの領域を除いた値であることを特徴とする請求項２に記載の極端紫外線露光用マスク。   A region in which the capping film is formed of Ru, and the Si film thickness immediately below the capping film ranges from an integral multiple of one cycle of the multilayer film including 0 to a quarter of one cycle of the multilayer film. The extreme ultraviolet exposure mask according to claim 2, wherein the value is a value excluding
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KR20140008246A (en) 2012-07-11 2014-01-21 아사히 가라스 가부시키가이샤 Reflective mask blank for euv lithography and process for its production, as well as substrate with reflective layer for such mask blank and process for its production
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Publication number Priority date Publication date Assignee Title
JP2010212484A (en) * 2009-03-11 2010-09-24 Toppan Printing Co Ltd Reflection type photomask blank and reflection type photomask
KR20140008246A (en) 2012-07-11 2014-01-21 아사히 가라스 가부시키가이샤 Reflective mask blank for euv lithography and process for its production, as well as substrate with reflective layer for such mask blank and process for its production
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KR102127230B1 (en) 2012-12-06 2020-07-07 칼 짜이스 에스엠테 게엠베하 Reflective optical element for euv lithography and method of manufacturing a reflective optical element
WO2022186004A1 (en) * 2021-03-02 2022-09-09 Hoya株式会社 Substrate with multilayer reflective film, reflective mask blank, reflective mask, and method for manufacturing semiconductor device

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