JP5215421B2 - Phase shift photomask blank, phase shift photomask, and semiconductor device manufacturing method - Google Patents
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Description
本発明は、多層膜の位相シフト膜からなる位相シフトフォトマスクブランクス及び位相シフトフォトマスク、並びにこのマスクを用いた半導体装置の製造方法に関し、特に減衰型（ハーフトーン）位相シフトフォトマスク及びこのマスクを製作するための位相シフトフォトマスクブランクス、並びにこのマスクを用いた半導体装置の製造方法に関する。 The present invention relates to a phase shift photomask blank and a phase shift photomask made of a multilayer phase shift film, and a method of manufacturing a semiconductor device using the mask, and more particularly to an attenuation type (halftone) phase shift photomask and the mask. The present invention relates to a phase shift photomask blank for manufacturing a semiconductor device and a method for manufacturing a semiconductor device using the mask.
従来、減衰型の位相シフトフォトマスクとして、単層膜からなるもの（特許文献１）及び２層膜からなるもの（特許文献２）が提案されている。単層膜からなるものについてはその膜構成を図１に、２層膜からなるものについてはその膜構成を図２に示す。 Conventionally, attenuating type phase shift photomasks having a single layer film (Patent Document 1) and a double layer film (Patent Document 2) have been proposed. The film structure of a single layer film is shown in FIG. 1, and the film structure of a double layer film is shown in FIG.
近年の半導体集積回路技術の発展に伴ってパターンの微細化が進むにつれ、露光波長が短波長化し、露光波長の光を減衰させる減衰型の位相シフトフォトマスクに対しては、次のような性能が要求されている。
（１）位相差（ＰＳ）は、ＰＳ＝１７５〜１８０°であること。
（２）露光波長（λｅｘｐ）における透過率（Ｔｅｘｐ）は、Ｔｅｘｐ＝２〜３０％であること。
（３）検査波長（λｉｎｓｐ）における透過率（Ｔｉｎｓｐ）は、Ｔｉｎｓｐ＜約４０〜５０％（例えば、λｅｘｐ＝１９３ｎｍのとき、λｉｎｓｐ＝３６５ｎｍ）であること。
（４）露光波長における反射率（Ｒｅｘｐ）は、好ましくは、Ｒｅｘｐ＜約２０％であること。
（５）膜厚ｄは薄い方が好ましいこと。
With the recent development of semiconductor integrated circuit technology, as the miniaturization of patterns progresses, the following performance is achieved for the attenuated phase shift photomask that shortens the exposure wavelength and attenuates the light at the exposure wavelength. Is required.
(1) The phase difference (PS) is PS = 175 to 180 °.
(2) the transmittance at the exposure wavelength (lambda exp) (T exp), it is T exp = 2~30%.
(3) The transmittance (T insp ) at the inspection wavelength (λ insp ) is T insp <about 40 to 50% (for example, λ insp = 365 nm when λ exp = 193 nm).
(4) The reflectance (R exp ) at the exposure wavelength is preferably R exp <about 20%.
(5) A thinner film thickness d is preferable.
上記従来技術の位相シフト膜の場合、露光波長（λｅｘｐ）を短波長化（例えば、ＡｒＦエキシマレーザー露光の場合、λｅｘｐ＝１９３ｎｍ）すると、露光波長における透過率（Ｔｅｘｐ）が上記要求透過率よりも低くなってしまう。そのため、露光波長における要求透過率を確保しようとして、この透過率（Ｔｅｘｐ）を高くすると、欠陥検査波長における透過率も高くなり過ぎるという問題が生じる。例えば、図２に示す２層膜においては、上記従来技術の場合、空気（屈折率：ｎ０）その他の気体のような周囲環境に接する上層の膜の屈折率（ｎ１−ｉｋ１）が下層の膜の屈折率（ｎ２−ｉｋ２）よりも大きいため、露光波長における透過率が小さくなり、例えばＡｒＦエキシマレーザーの波長に対して満足すべき透過率が得られないという問題がある。これに対して、露光波長における透過率を上げると、通常用いられる位相シフトフォトマスクの欠陥検査波長（例えば、λｉｎｓｐ＝３６５ｎｍ）における透過率が大きくなり過ぎるため、欠陥検査が不可能となる。このように、上記従来技術では、近年の半導体集積回路技術の発展に対応しきれなくなっている。 In the case of the phase shift film of the above prior art, when the exposure wavelength (λ exp ) is shortened (for example, in the case of ArF excimer laser exposure, λ exp = 193 nm), the transmittance (T exp ) at the exposure wavelength is the required transmission. It will be lower than the rate. Therefore, if the transmittance (T exp ) is increased in order to secure the required transmittance at the exposure wavelength, there is a problem that the transmittance at the defect inspection wavelength becomes too high. For example, in the two-layer film shown in FIG. 2, the refractive index (n 1 -ik 1 ) of the upper film in contact with the surrounding environment such as air (refractive index: n 0 ) or other gas in the case of the above-described prior art. Since it is larger than the refractive index (n 2 -ik 2 ) of the lower layer film, there is a problem that the transmittance at the exposure wavelength becomes small, and for example, a satisfactory transmittance cannot be obtained for the wavelength of ArF excimer laser. On the other hand, when the transmittance at the exposure wavelength is increased, the transmittance at a defect inspection wavelength (for example, λ insp = 365 nm) of a commonly used phase shift photomask becomes too large, so that defect inspection becomes impossible. As described above, the above-described conventional technology cannot cope with the recent development of semiconductor integrated circuit technology.
なお、欠陥検査装置メーカーの努力により、検査波長が短波長化する傾向にある。従って、検査波長（３６５ｎｍ）における透過率の多少の増大は問題とならなくなる可能性があるが、大幅な透過率増大は大分先にならないと解決されないと思われる。
本発明は、上記従来技術のもつ問題点を解決するものであり、短波長の露光波長に対しても十分な透過率が得られ、使用可能であると共に、欠陥検査波長に対しても適切な透過率を有し、満足すべき検査が可能となる位相シフトフォトマスク及びこのマスクを製作するための位相シフトフォトマスクブランクス、並びにこのマスクを用いた半導体装置の製造方法を提供することを課題とする。
The inspection wavelength tends to be shortened by the efforts of the defect inspection apparatus manufacturer. Therefore, although a slight increase in the transmittance at the inspection wavelength (365 nm) may not be a problem, it seems that the substantial increase in the transmittance cannot be solved unless it is far ahead.
The present invention solves the above-mentioned problems of the prior art, and can provide a sufficient transmittance even for an exposure wavelength of a short wavelength and can be used, and is also suitable for a defect inspection wavelength. PROBLEM TO BE SOLVED: To provide a phase shift photomask having transmittance and enabling satisfactory inspection, a phase shift photomask blank for manufacturing the mask, and a method of manufacturing a semiconductor device using the mask. To do.
本発明者らは、上記従来技術の問題点を解決すべく鋭意研究を重ねた結果、膜の屈折率に着目し、多層膜からなる位相シフト膜の構成を最適化することによって、これらの問題の解決を図り、本発明を完成するに至った。 As a result of intensive studies to solve the problems of the above-described conventional techniques, the inventors have paid attention to the refractive index of the film and optimized the configuration of the phase shift film composed of a multilayer film. As a result, the present invention has been completed.
本発明の位相シフトフォトマスクブランクスは、ハーフトーン位相シフト膜がＭｏＳｉＯＮ膜で２層からなり、波長１９３ｎｍおよび波長３６５ｎｍに対する上層の膜の屈折率及び消衰係数が下層の膜の屈折率及び消衰係数よりも小さく、波長３６５ｎｍに対する透過率を３４．３６％〜５５．１７％とし、波長１９３ｎｍに対する反射率を３．２１〜７．４０％とすることを特徴とし、これにより、露光波長における透過率が高くかつ反射率が低いものが得られる。 In the phase shift photomask blank of the present invention, the halftone phase shift film is composed of two layers of MoSiON films, and the refractive index and extinction coefficient of the upper film with respect to the wavelength of 193 nm and the wavelength of 365 nm are the refractive index and extinction coefficient of the lower film. The transmittance is 34.36% to 55.17% for the wavelength 365 nm, and the reflectance for the wavelength 193 nm is 3.21 to 7.40%. A high rate and low reflectivity is obtained.
また、本発明の位相シフトフォトマスクブランクスは、ハーフトーン位相シフト膜が３層からなり、中間層の膜の屈折率及び消衰係数が上層及び下層の膜の屈折率及び消衰係数よりも小さいことを特徴とし、これにより、欠陥検査波長における透過率が低くなり、検査が可能となる。３層膜からなる位相シフト膜の場合、基準となる膜構成として、例えば、空気その他の気体／ｎ１、ｋ１、ｄ１／ｎ２、ｋ２、ｄ２／ｎ３、ｋ３、ｄ３／透明基板（ただし、ｎ１、ｎ２、ｎ３はそれぞれ上層、中間層、下層の膜の屈折率であり、ｋ１、ｋ２、ｋ３はそれぞれ、上層、中間層、下層の膜の消衰係数であり、ｄ１、ｄ２、ｄ３はそれぞれ上層、中間層、下層の膜厚である。）のような構成を考えることができる。 In the phase shift photomask blank of the present invention, the halftone phase shift film is composed of three layers, and the refractive index and extinction coefficient of the intermediate layer film are smaller than the refractive index and extinction coefficient of the upper layer and lower layer films. As a result, the transmittance at the defect inspection wavelength is low, and inspection is possible. In the case of a phase shift film composed of a three-layer film, as a reference film configuration, for example, air or other gas / n 1 , k 1 , d 1 / n 2 , k 2 , d 2 / n 3 , k 3 , d 3 / transparent substrate (where n 1 , n 2 , and n 3 are the refractive indexes of the upper layer, intermediate layer, and lower layer, respectively, and k 1 , k 2 , and k 3 are the upper layer, intermediate layer, and lower layer films, respectively. And d 1 , d 2 , and d 3 are the film thicknesses of the upper layer, the intermediate layer, and the lower layer, respectively).
前記ハーフトーン位相シフト膜はＭｏＳｉＯＮ系の膜である。その他にＭｏＳｉＮ系の膜、ＭｏＳｉＯ系の膜等であってもよい。 The halftone phase shift film is a MoSiON film. In addition, a MoSiN film, a MoSiO film, or the like may be used.
本発明の位相シフトフォトマスクは、上記位相シフトフォトマスクブランクスにウエハー基板に転写すべきパターンが形成されたものであり、この位相シフトフォトマスクを用いて露光を行い、微細なパターンを有する半導体装置を製造することができる。 The phase shift photomask of the present invention is a semiconductor device having a fine pattern in which a pattern to be transferred to a wafer substrate is formed on the above phase shift photomask blank, and exposure is performed using this phase shift photomask. Can be manufactured.
なお、露光波長として、上記したＡｒＦエキシマレーザー露光の場合（λｅｘｐ＝１９３ｎｍ）の他に、Ｆ２レーザー露光の場合、λｅｘｐ＝１５７ｎｍ、ＫｒＦエキシマレーザー露光の場合、λｅｘｐ＝２４８ｎｍ等が用いられ得る。 In addition to the ArF excimer laser exposure (λ exp = 193 nm), λ exp = 157 nm is used for the F 2 laser exposure, and λ exp = 248 nm is used for the KrF excimer laser exposure. Can be.
本発明によれば、減衰型（ハーフトーン）の位相シフト膜を２層構成とし、上層の膜の屈折率及び消衰係数を下層の膜の屈折率及び消衰係数よりも小さくしたので、露光波長における透過率が高くかつ反射率が低いものが得られる。
また、本発明によれば、減衰型の位相シフト膜を３層構成とし、中間層の膜の屈折率及び消衰係数を上層及び下層の膜の屈折率及び消衰係数よりも小さくしたので、欠陥検査波長における透過率が低くなり、欠陥検査が可能になる。
さらに、本発明によれば、減衰型の位相シフト膜を３層以上の構成とし、最上層の膜の屈折率及び消衰係数をその直ぐ下の層の膜の屈折率及び消衰係数よりも小さくしたので、露光波長における透過率が高くかつ反射率が低いものが得られる。
さらにまた、本発明の位相シフトフォトマスクブランクスは、ＡｒＦエキシマレーザー露光用位相シフトフォトマスクを得るのに大変有効であり、このフォトマスクを用いて微細なパターンを有する半導体装置の製造が可能になる。
According to the present invention, the attenuation type (halftone) phase shift film has a two-layer structure, and the refractive index and extinction coefficient of the upper film are made smaller than the refractive index and extinction coefficient of the lower film. A high transmittance at a wavelength and a low reflectance can be obtained.
Further, according to the present invention, the attenuation type phase shift film has a three-layer configuration, and the refractive index and extinction coefficient of the intermediate layer film are made smaller than the refractive index and extinction coefficient of the upper layer and lower layer films. The transmittance at the defect inspection wavelength is lowered, and defect inspection becomes possible.
Further, according to the present invention, the attenuation type phase shift film has three or more layers, and the refractive index and extinction coefficient of the uppermost layer film are set to be higher than the refractive index and extinction coefficient of the film immediately below. Since the size is reduced, a high transmittance and low reflectance at the exposure wavelength can be obtained.
Furthermore, the phase shift photomask blank of the present invention is very effective for obtaining a phase shift photomask for ArF excimer laser exposure, and a semiconductor device having a fine pattern can be manufactured using this photomask. .
以下、本発明の実施例及び比較例を図面を参照して説明する。雰囲気ガスは空気とした（ｎ０＝１）。
（実施例１）
本実施例では、図１〜５に基づき、本発明の２層膜及び３層膜の膜構成の最適化について従来技術と比較して説明する。
図１に示すような単層膜の場合、位相シフト膜ｆを透過する光Ｆと位相シフト膜の開口部ｑを透過する光Ｑとの位相差（ＰＳ）は次式で与えられる。
ＰＳ ＝ ２π(ｎ１−ｎ０)ｄ１ ／λ （１）
ＰＳ＝１８０°（π）になる膜厚ｄ１ ０は次式で与えられる。
ｄ１ ０ ＝ λｅｘｐ／２(ｎ１−ｎ０) （２）
上式中、ｎ１は位相シフト膜の屈折率であり、ｎ０は空気の屈折率（ｎ０＝１）であり、ｄ１は位相シフト膜の膜厚であり、λｅｘｐは露光波長である。
図２に示すような２層膜の場合、位相シフト膜を透過する光Ｆと位相シフト膜の開口部を透過する光Ｑとの位相差（ＰＳ）は次式で与えられる。
ＰＳ ＝ ＰＳ１＋ＰＳ２ （３）
ここに、ＰＳ１及びＰＳ２は次式で与えられる。
ＰＳ１ ＝ ２π(ｎ１−ｎ０)ｄ１ ／λｅｘｐ （４）
ＰＳ２ ＝ ２π(ｎ２−ｎ０)ｄ２ ／λｅｘｐ （５）
上式（３）、（４）、（５）からＰＳ＝πとなる条件は、次式である。
ｄ１／ｄ１ ０＋ｄ２／ｄ２ ０ ＝ １ （６）
ここに、ｄ１ ０ 及びｄ２ ０ は次式で与えられる。
ｄ１ ０ ＝ λｅｘｐ ／２(ｎ１−ｎ０) （７）
ｄ２ ０ ＝ λｅｘｐ ／２(ｎ２−ｎ０) （８）
上式中、ＰＳ１及びＰＳ２はそれぞれ上層及び下層の膜の位相差であり、ｎ１及びｎ２はそれぞれ上層及び下層の膜の屈折率であり、ｄ１及びｄ２はそれぞれ上層及び下層の膜の膜厚であり、ｄ１ ０ 及びｄ２ ０ はそれぞれ上層及び下層の膜の位相差が１８０°になる膜厚であり、λｅｘｐは露光波長である。
図３に示すような３層膜の場合、位相シフト膜を透過する光Ｆと位相シフト膜の開口部を透過する光Ｑとの位相差（ＰＳ）は次式で与えられる。
ＰＳ ＝ ＰＳ１＋ＰＳ２＋ＰＳ３ （９）
ここに、ＰＳ１、ＰＳ２及びＰＳ３は次式で与えられる。
ＰＳ１ ＝ ２π(ｎ１−ｎ０)ｄ１ ／λｅｘｐ （１０）
ＰＳ２ ＝ ２π(ｎ２−ｎ０)ｄ２ ／λｅｘｐ （１１）
ＰＳ３ ＝ ２π(ｎ３−ｎ０)ｄ３ ／λｅｘｐ （１２）
上式（９）〜（１２）からＰＳ＝πとなる条件は、次式である。
ｄ１／ｄ１ ０＋ｄ２／ｄ２ ０＋ｄ３／ｄ３ ０ ＝ １ （１３）
ここに、ｄ１ ０ 、ｄ２ ０ 及びｄ３ ０ は次式で与えられる。
ｄ１ ０ ＝ λｅｘｐ ／２(ｎ１−ｎ０) （１４）
ｄ２ ０ ＝ λｅｘｐ ／２(ｎ２−ｎ０) （１５）
ｄ３ ０ ＝ λｅｘｐ ／２(ｎ３−ｎ０) （１６）
上式中、ＰＳ１、ＰＳ２及びＰＳ３はそれぞれ上層、中間層及び下層の膜の位相差であり、ｎ１、ｎ２及びｎ３はそれぞれ上層、中間層及び下層の膜の屈折率であり、ｎ０は空気の屈折率（ｎ０＝１）であり、ｄ１、ｄ２及びｄ３はそれぞれ上層、中間層及び下層の膜の膜厚であり、ｄ１ ０、ｄ２ ０及びｄ３ ０はそれぞれ上層、中間層及び下層の膜の位相差が１８０°になる膜厚であり、λｅｘｐは露光波長である。
Examples of the present invention and comparative examples will be described below with reference to the drawings. The atmosphere gas was air (n 0 = 1).
Example 1
In the present embodiment, the optimization of the film configuration of the two-layer film and the three-layer film of the present invention will be described based on FIGS.
In the case of a single layer film as shown in FIG. 1, the phase difference (PS) between the light F transmitted through the phase shift film f and the light Q transmitted through the opening q of the phase shift film is given by the following equation.
PS = 2π (n 1 −n 0 ) d 1 / λ (1)
Thickness d 1 0 to be PS = 180 ° (π) is given by the following equation.
d 1 0 = λ exp / 2 (n 1 −n 0 ) (2)
In the above formula, n 1 is the refractive index of the phase shift film, n 0 is the refractive index of air (n 0 = 1), d 1 is the film thickness of the phase shift film, and λ exp is the exposure wavelength. is there.
In the case of a two-layer film as shown in FIG. 2, the phase difference (PS) between the light F transmitted through the phase shift film and the light Q transmitted through the opening of the phase shift film is given by the following equation.
PS = PS 1 + PS 2 (3)
Here, PS 1 and PS 2 are given by the following equations.
PS 1 = 2π (n 1 −n 0 ) d 1 / λ exp (4)
PS 2 = 2π (n 2 −n 0 ) d 2 / λ exp (5)
From the above equations (3), (4), and (5), the condition that PS = π is the following equation.
d 1 / d 1 0 + d 2 / d 2 0 = 1 (6)
Here, d 1 0 and d 2 0 are given by the following equations.
d 1 0 = λ exp / 2 (n 1 −n 0 ) (7)
d 2 0 = λ exp / 2 (n 2 −n 0 ) (8)
In the above formula, PS 1 and PS 2 are the phase differences of the upper and lower layers, n 1 and n 2 are the refractive indices of the upper and lower layers, respectively, and d 1 and d 2 are the upper and lower layers, respectively. D 1 0 and d 2 0 are film thicknesses where the phase difference between the upper and lower films is 180 °, respectively, and λ exp is the exposure wavelength.
In the case of a three-layer film as shown in FIG. 3, the phase difference (PS) between the light F transmitted through the phase shift film and the light Q transmitted through the opening of the phase shift film is given by the following equation.
PS = PS 1 + PS 2 + PS 3 (9)
Here, PS 1 , PS 2 and PS 3 are given by the following equations.
PS 1 = 2π (n 1 −n 0 ) d 1 / λ exp (10)
PS 2 = 2π (n 2 −n 0 ) d 2 / λ exp (11)
PS 3 = 2π (n 3 −n 0 ) d 3 / λ exp (12)
From the above formulas (9) to (12), the condition that PS = π is the following formula.
d 1 / d 1 0 + d 2 / d 2 0 + d 3 / d 3 0 = 1 (13)
Here, d 1 0 , d 2 0 and d 3 0 are given by the following equations.
d 1 0 = λ exp / 2 (n 1 −n 0 ) (14)
d 2 0 = λ exp / 2 (n 2 −n 0 ) (15)
d 3 0 = λ exp / 2 (n 3 −n 0 ) (16)
In the above formula, PS 1 , PS 2 and PS 3 are the phase differences of the upper layer, intermediate layer and lower layer film, respectively, and n 1 , n 2 and n 3 are the refractive indices of the upper layer, intermediate layer and lower layer film, respectively. N 0 is the refractive index of air (n 0 = 1), d 1 , d 2 and d 3 are the film thicknesses of the upper layer, intermediate layer and lower layer, respectively, d 1 0 , d 2 0 and d 3 0 is the thickness of the upper layer, the phase difference between the intermediate layer and the lower layer of the film is 180 ° respectively, the lambda exp is the exposure wavelength.
図１、２及び３中のｎｓは基板の屈折率であり、図１中のｋ１は位相シフト膜の上層の膜の消衰係数であり、図２中のｋ１及びｋ２はそれぞれ上層及び下層の膜の消衰係数であり、また、図３中のｋ１、ｋ２及びｋ３はそれぞれ上層、中間層及び下層の膜の消衰係数である。 N s in Figures 1, 2 and 3 is the refractive index of the substrate, k 1 in FIG. 1 is a extinction coefficient of the upper layer of the film of the phase shift film, k 1 and k 2 in Fig. 2, respectively The extinction coefficients of the upper layer and lower layer films, and k 1 , k 2 and k 3 in FIG. 3 are the extinction coefficients of the upper layer, intermediate layer and lower layer film, respectively.
以下に示す表１、表２において、ＲＲはアルミニウム真空蒸着膜に対する反射率（相対反射率）、ＰＳ０は膜の吸収を無視したときの位相差、ＰＳは膜の吸収を考慮したときの位相差を表す。
上記したように、単層膜、２層膜、３層膜の場合について、位相差πを与える条件について説明したが、以下、２層膜及び３層膜の最適化について説明する。
In Tables 1 and 2 below, RR is the reflectance (relative reflectance) with respect to the aluminum vacuum deposited film, PS0 is the phase difference when the film absorption is ignored, and PS is the phase difference when the film absorption is considered. Represents.
As described above, the conditions for giving the phase difference π have been described in the case of a single layer film, a two layer film, and a three layer film. Hereinafter, optimization of the two layer film and the three layer film will be described.
先ず、２層膜の最適化について説明する。上式（６）から、位相差πを与える位相シフト膜の各層の膜厚（オングストローム）ｄ１とｄ２との間には、図４に示すような直線関係がある。この直線に沿った各点Ｆ１１、Ｆ１２、Ｆ２１〜Ｆ２７について、光学特性を計算した結果を表１に示した。その際、位相シフト膜の光学定数は、表４に示すＭｏＳｉＯＮスパッター膜（３５０℃、３時間焼鈍品）のＱ：１１、Ｑ：１３についての値を用いた。表１において、ｆ１は上層の膜の屈折率が下層の膜の屈折率より高い構成のもの（従来膜）、ｆ２はその逆の構成のもの（本発明膜）を表す。表１より、露光波長１９３ｎｍにおける透過率Ｔ１９３については、ｆ２の方がｆ１よりも高くなることがわかる。また、露光波長１９３ｎｍにおける反射率ＲＲ１９３については、ｆ２の方がｆ１よりも低くなって、好ましい方向へ行くことがわかる。 First, the optimization of the two-layer film will be described. From the above equation (6), there is a linear relationship as shown in FIG. 4 between the film thicknesses (angstroms) d 1 and d 2 of each layer of the phase shift film giving the phase difference π. Table 1 shows the result of calculating the optical characteristics of the points F 11 , F 12 , and F 21 to F 27 along the straight line. At that time, as the optical constant of the phase shift film, values for Q: 11 and Q: 13 of the MoSiON sputtered film (350 ° C., 3 hour annealed product) shown in Table 4 were used. In Table 1, f 1 represents a structure in which the refractive index of the upper film is higher than the refractive index of the lower film (conventional film), and f 2 represents the reverse structure (invention film). From Table 1, it can be seen that f 2 is higher than f 1 for transmittance T 193 at an exposure wavelength of 193 nm. In addition, with respect to the reflectance RR 193 at the exposure wavelength of 193 nm, it can be seen that f 2 is lower than f 1 and goes in a preferred direction.
従って、ｆ１（従来膜）のように、上層の膜の屈折率が下層の膜の屈折率よりも高い位相シフト膜よりも、上層の膜の屈折率が下層の膜の屈折率よりも低い位相シフト膜の方が好ましい。 Therefore, the refractive index of the upper film is lower than the refractive index of the lower film than the phase shift film in which the refractive index of the upper film is higher than the refractive index of the lower film as in f 1 (conventional film). A phase shift film is preferred.
次に、３層膜の最適化について説明する。上式（１３）から、位相差πを与える位相シフト膜の各層の膜厚（オングストローム）ｄ１、ｄ２及びｄ３は、図５に示すように、平面Ｆ１１−Ｆ１２−Ｆ１３を３辺とする平面上の点で与えられる。この平面上の点Ｆ３１、Ｆ３２、Ｆ３３、Ｆ３４についての光学特性の計算結果を表２に示した。表２には、単層膜Ｆ１１、Ｆ１２、Ｆ１３、及び２層膜Ｆ２１、Ｆ２２、Ｆ２３についての計算結果を比較のために示した。表２における膜の基本構成Ｆ３ｊ（ｊ＝１〜４）及び膜ｆ１〜ｆ６の詳細は表３に示す通りである。また、位相シフト膜の光学定数は、表４に示すＭｏＳｉＯＮスパッター膜のＱ：１１、Ｑ：２５、Ｑ：１３についての値を用いた。 Next, optimization of the three-layer film will be described. From the above equation (13), the film thicknesses (angstroms) d 1 , d 2, and d 3 of the phase shift film that give the phase difference π are expressed by the planes F 11 -F 12 -F 13 as shown in FIG. It is given as a point on a plane with three sides. Table 2 shows the calculation results of the optical characteristics for the points F 31 , F 32 , F 33 , and F 34 on this plane. Table 2 shows the calculation results for the single-layer films F 11 , F 12 , F 13 and the two-layer films F 21 , F 22 , F 23 for comparison. Details of the basic structure F 3j (j = 1 to 4) and the films f 1 to f 6 in Table 2 are as shown in Table 3. As the optical constant of the phase shift film, the values for Q: 11, Q: 25, and Q: 13 of the MoSiON sputtered film shown in Table 4 were used.
表２から、次のことがわかる。膜ｆ１〜ｆ６のうち、露光波長１９３ｎｍにおける透過率Ｔ１９３はｆ２、ｆ４、ｆ６の膜が高く、欠陥検査波長３６５ｎｍにおける透過率Ｔ３６５はｆ３、ｆ５の膜が低い。また、露光波長１９３ｎｍにおける反射率ＲＲ１９３はｆ１、ｆ３膜よりもｆ２、ｆ４、ｆ５、ｆ６膜の方が低い。 Table 2 shows the following. Among the films f 1 to f 6 , the transmittance T 193 at the exposure wavelength 193 nm is high for the films f 2 , f 4 and f 6 , and the transmittance T 365 at the defect inspection wavelength 365 nm is low for the films f 3 and f 5. . Further, the reflectance RR 193 at the exposure wavelength of 193 nm is lower in the f 2 , f 4 , f 5 , and f 6 films than in the f 1 and f 3 films.
従って、１９３ｎｍ露光用位相シフト膜としては、露光波長における透過率を高くするには、ｆ２、ｆ４、ｆ６の膜、すなわち上層の膜が中間層の膜よりも低い屈折率をもつことが好ましく、また、欠陥検査波長における透過率を低くするには、ｆ３、ｆ５の膜、すなわち中間層の膜の屈折率が上層及び下層の膜の両方よりも低いことが好ましい。 Therefore, as a phase shift film for 193 nm exposure, in order to increase the transmittance at the exposure wavelength, the films of f 2 , f 4 , and f 6 , that is, the upper film has a lower refractive index than the film of the intermediate layer. In order to reduce the transmittance at the defect inspection wavelength, it is preferable that the refractive indexes of the films of f 3 and f 5 , that is, the film of the intermediate layer are lower than both the upper layer and the lower layer.
以上の実施例においては、２層膜及び３層膜の最適化について説明したが、４層以上のハーフトーン位相シフト膜の場合についても、最上層の膜の屈折率がその直下層の膜の屈折率よりも小さいものからなる位相シフト膜であれば、最適化され、上記で説明したのと同じように露光波長における透過率が高いものが得られる。 In the above embodiment, the optimization of the two-layer film and the three-layer film has been described, but the refractive index of the uppermost film is the same as that of the film immediately below it even in the case of four or more halftone phase shift films. A phase shift film made of a material having a refractive index smaller than that of the refractive index is optimized, and a film having a high transmittance at the exposure wavelength is obtained in the same manner as described above.
実施例２（位相シフトフォトマスクブランクスの製作）
平板型直流マグネトロン装置を用いて、特開平６−２２０６２７号公報、特開平８−１２７８７０号公報、及びN.Motegi, Y.Kashimoto, K.Nagatani et al., J. Vacuum Sci. Technol., Vol. B13(4),1995,pp.1906-1909 等に記載され、示されたいわゆるＬＴＳ（ロングスロースパッタリング）法に従って透明基板上にモリブデンシリサイド酸化窒化膜を形成した。すなわち、この装置内にＭｏＳｉ２ターゲットを設置し、圧力０．０５３３〜０．１０７Ｐａ（４〜８×１０−４Ｔｏｒｒ）の下、ＡｒガスとＮ２Ｏガスとを表４に示す流量及び流量比で用いる反応性スパッタリングによって、６インチ（１５２．４ｍｍ）角の厚さ０．２５インチ（６．３５ｍｍ）の６０２５石英基板の上にＭｏＳｉＯＮ膜を形成した。成膜後、３５０℃で３時間の熱処理を施して２層膜及び３層膜のＭｏＳｉＯＮ膜を位相シフト膜とする位相シフトフォトマスクブランクスを製作した。この膜構成は表１及び表２に記載された本発明の膜構成とした。製作されたＭｏＳｉＯＮ系スパッター膜に関し、反応ガス流量比（Ｎ２Ｏ／Ａｒ＋Ｎ２Ｏ、ｖｏｌ％）と光学定数との間の関係は図６及び表４に示す通りであった。図６及び表４から明らかなように、反応ガス流量比が大きい程、屈折率ｎと消衰係数ｋは小さくなることがわかる。すなわち、ＭｏＳｉＯＮ膜の酸窒化度が高い程、屈折率ｎ及び消衰係数ｋは小さくなる。
Example 2 (Production of phase shift photomask blanks)
By using a flat plate type DC magnetron apparatus, Japanese Patent Application Laid-Open Nos. 6-262027, 8-127870, and N. Motegi, Y. Kashimoto, K. Nagatani et al., J. Vacuum Sci. Technol., Vol. A molybdenum silicide oxynitride film was formed on a transparent substrate according to the so-called LTS (long throw sputtering) method described and shown in B13 (4), 1995, pp. 1906-1909. That is, a MoSi 2 target is installed in this apparatus, and Ar gas and N 2 O gas are flow rates and flow rates shown in Table 4 under a pressure of 0.0533 to 0.107 Pa (4 to 8 × 10 −4 Torr). A MoSiON film was formed on a 625 (152.4 mm) square 0.25 inch (6.35 mm) 6025 quartz substrate by reactive sputtering used in the ratio. After the film formation, a heat treatment was performed at 350 ° C. for 3 hours to manufacture a phase shift photomask blank using a two-layer film and a three-layer MoSiON film as a phase shift film. This film structure was the film structure of the present invention described in Tables 1 and 2. Regarding the manufactured MoSiON-based sputtered film, the relationship between the reaction gas flow rate ratio (N 2 O / Ar + N 2 O, vol%) and the optical constant was as shown in FIG. As apparent from FIG. 6 and Table 4, it can be seen that the larger the reaction gas flow rate ratio, the smaller the refractive index n and the extinction coefficient k. That is, the higher the oxynitridation degree of the MoSiON film, the smaller the refractive index n and the extinction coefficient k.
また、位相シフト膜としてＭｏＳｉＯＮ系スパッター膜の代わりに、ＭｏＳｉＮ系スパッター膜、ＭｏＳｉＯ系スパッター膜を用いた場合も同じような傾向が見られる。 The same tendency is observed when a MoSiN-based sputtered film or a MoSiO-based sputtered film is used as the phase shift film instead of the MoSiON-based sputtered film.
実施例３（位相シフトフォトマスクの製作）
実施例２で得た位相シフトフォトマスクブランクス上に電子ビーム用レジスト（例えば、日本ゼオン株式会社製のＺＥＰ−８１０Ｓ等）を塗布し、約５０００オングストローム厚さのレジスト膜を形成した。次いで、パターン露光、現像、ドライエッチング、洗浄等の一連の周知のパターン形成処理を施して、位相シフト膜の一部をエッチング除去し、開口部と位相シフト膜とで、ホール或いはドット等のパターンの形成された位相シフトフォトマスクを製作した。この際のドライエッチングは、平行平板型のＲＦイオンエッチング装置を用い、電極間距離６０ｍｍ、作動圧力４０Ｐａ（０．３Ｔｏｒｒ）で、ＣＦ４＋Ｏ２混合ガスを用いて、それぞれの流量比を約９５容量％及び５容量％で実施した。このようにして微細なパターンを有するフォトマスクの製作が可能であった。
Example 3 (Production of phase shift photomask)
An electron beam resist (for example, ZEP-810S manufactured by Nippon Zeon Co., Ltd.) was applied on the phase shift photomask blank obtained in Example 2 to form a resist film having a thickness of about 5000 angstroms. Next, a series of well-known pattern forming processes such as pattern exposure, development, dry etching, and cleaning are performed to remove a part of the phase shift film, and a pattern such as a hole or a dot is formed between the opening and the phase shift film. A phase shift photomask with the above structure was manufactured. In this dry etching, a parallel plate type RF ion etching apparatus is used, the distance between the electrodes is 60 mm, the working pressure is 40 Pa (0.3 Torr), and a CF 4 + O 2 mixed gas is used. Performed in volume% and 5 volume%. In this way, it was possible to produce a photomask having a fine pattern.
実施例４（半導体装置の製造）
実施例３で得られた位相シフトフォトマスクを用いて、露光光としてＡｒＦエキシマレーザー光を使用した露光を行い、感光材の塗布されたウェハー基板上にフォトマスクの所定のパターンを転写し、次いで現像してこの所定のパターンをウェハー上に形成した。以下、公知の製造工程に従って半導体装置を製造した。かくして得られた半導体装置は微細なパターンを有していた。
Example 4 (Manufacture of semiconductor devices)
Using the phase shift photomask obtained in Example 3, exposure is performed using ArF excimer laser light as exposure light, a predetermined pattern of the photomask is transferred onto the wafer substrate coated with the photosensitive material, and then Development was performed to form this predetermined pattern on the wafer. Hereinafter, a semiconductor device was manufactured according to a known manufacturing process. The semiconductor device thus obtained had a fine pattern.
ｆ 位相シフト膜
Ｆ 位相シフト膜を通過する光
ｑ 位相シフト膜の開口部
Ｑ 位相シフト膜の開口部を透過する光
ｎ０ 空気の屈折率
ｄ１、ｄ２、ｄ３ 位相シフト膜の各層の膜厚
ｎ１−ｉｋ１、ｎ２−ｉｋ２、ｎ３−ｉｋ３ 位相シフト膜の各層の膜の複素屈折率
ｎｓ 基板の屈折率
ｋ１、ｋ２、ｋ３ 位相シフト膜の各層の膜の消衰係数
f Phase shift film F Light passing through phase shift film q Phase shift film opening Q Light passing through phase shift film opening n 0 Refractive index of air d 1 , d 2 , d 3 Phase shift film Film thickness n 1 -ik 1 , n 2 -ik 2 , n 3 -ik 3 Phase shift film complex refractive index n s substrate refractive index k 1 , k 2 , k 3 phase shift film of each layer Membrane extinction coefficient
Claims (9)
波長３６５ｎｍに対する透過率を３４．３６％〜５５．１７％とし、
波長１９３ｎｍに対する反射率を３．２１〜７．４０％とすることを特徴とする位相シフトフォトマスクブランクス。 The halftone phase shift film consists of two layers of MoSiON films, and the refractive index and extinction coefficient of the upper layer with respect to the wavelength of 193 nm and the wavelength of 365 nm are smaller than the refractive index and extinction coefficient of the lower layer film,
The transmittance for a wavelength of 365 nm is 34.36% to 55.17% ,
A phase shift photomask blank characterized in that the reflectance for a wavelength of 193 nm is 3.21 to 7.40% .
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| JP6185721B2 (en) * | 2013-01-29 | 2017-08-23 | Hoya株式会社 | Mask blank, mask blank manufacturing method, transfer mask manufacturing method, and semiconductor device manufacturing method |
| JP2015219324A (en) * | 2014-05-15 | 2015-12-07 | 大日本印刷株式会社 | Defect inspection method of photomask |
| KR101810805B1 (en) * | 2014-12-26 | 2017-12-19 | 호야 가부시키가이샤 | Mask blank, phase-shift mask, method for manufacturing phase-shift mask and method for manufacturing semiconductor device |
| KR102427106B1 (en) * | 2017-11-24 | 2022-08-01 | 호야 가부시키가이샤 | Mask blank, phase shift mask, phase shift mask manufacturing method, and semiconductor device manufacturing method |
| KR102273211B1 (en) * | 2020-08-25 | 2021-07-05 | 에스케이씨솔믹스 주식회사 | Blankmask and photomask using the same |
| KR102368448B1 (en) * | 2021-02-10 | 2022-02-25 | 에스케이씨솔믹스 주식회사 | Appratus for fabricating semiconductor device |
| KR102349367B1 (en) * | 2020-12-31 | 2022-01-07 | 에스케이씨솔믹스 주식회사 | Apparatus for manufacturing semiconductor device |
| KR102349368B1 (en) * | 2021-02-25 | 2022-01-07 | 에스케이씨솔믹스 주식회사 | Apparatus for manufacturing semiconductor device |
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| JP3064769B2 (en) * | 1992-11-21 | 2000-07-12 | アルバック成膜株式会社 | PHASE SHIFT MASK, ITS MANUFACTURING METHOD, AND EXPOSURE METHOD USING THE PHASE SHIFT MASK |
| JP3262302B2 (en) * | 1993-04-09 | 2002-03-04 | 大日本印刷株式会社 | Phase shift photomask, blank for phase shift photomask, and method of manufacturing the same |
| JP3115185B2 (en) * | 1993-05-25 | 2000-12-04 | 株式会社東芝 | Exposure mask and pattern forming method |
| JPH07253655A (en) * | 1994-03-15 | 1995-10-03 | Fujitsu Ltd | Exposure mask |
| JP3594659B2 (en) * | 1994-09-08 | 2004-12-02 | アルバック成膜株式会社 | Phase shift photomask blank manufacturing method, phase shift photomask blank, and phase shift photomask |
| JP3615801B2 (en) * | 1994-11-01 | 2005-02-02 | 株式会社アルバック | Titanium nitride thin film deposition method |
| JP3397933B2 (en) * | 1995-03-24 | 2003-04-21 | アルバック成膜株式会社 | Phase shift photomask blanks, phase shift photomasks, and manufacturing methods thereof. |
| JPH1116802A (en) * | 1997-06-19 | 1999-01-22 | Toshiba Corp | Method for exposure and aligner |
| JP3478067B2 (en) * | 1997-06-25 | 2003-12-10 | 凸版印刷株式会社 | Halftone phase shift mask and blank for halftone phase shift mask |
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