KR-20260064546-A - REFLECTIVE MASK BLANK AND METHOD FOR MANUFACTURING REFLECTIVE MASK

Abstract

[Problem] A protective film made of rhodium (Rh) or a protective film formed of a material containing rhodium (Rh) and ruthenium (Ru), wherein even when dry etching is performed using a gas containing oxygen (O) in a mask manufacturing process, the protective film is less likely to be damaged, thereby suppressing a reduction in the thickness of the protective film or oxidation of the protective film, and a method for manufacturing a reflective mask using the reflective mask blank is provided. [Solution] A reflective mask blank (100) serves as the material for a reflective mask (110) used in EUV lithography in which EUV light is used as the exposure light. The reflective mask blank (100) comprises a substrate (1), a multilayer reflective film (2) formed above one main surface of the substrate (1) that reflects the exposure light, a protective film (3) formed on the multilayer reflective film (2) that protects the multilayer reflective film (2), an absorbing film (5) formed above the protective film (3) that absorbs the exposure light, and an etching stop film (4) containing niobium (Nb) provided between the protective film (3) and the absorbing film (5). The protective film (3) has at least one layer containing rhodium (Rh). In the multilayer reflective film (2), the layer in contact with the protective film (3) contains Mo.

Inventors

• 이나즈키 유키오
• 고사카 다쿠로
• 오고세 다이가
• 사쿠라이 게이스케
• 미무라 쇼헤이
• 가네코 히데오

Assignees

• 신에쓰 가가꾸 고교 가부시끼가이샤

Dates

Publication Date

20260507

Application Date

20251023

Priority Date

20241030

Claims (6)

1. As a reflective mask blank that serves as the material for a reflective mask used in EUV lithography using EUV light as the exposure light, The substrate and, A multilayer reflective film that reflects exposure light formed above one main surface of the above substrate, and A protective film that protects the multilayer reflective film formed on the above multilayer reflective film, and An absorption film that absorbs exposure light formed above the above protective film, and An etching stop layer containing niobium (Nb) provided between the protective film and the absorption film. Equipped with, The above protective film has at least one layer containing rhodium (Rh), and A reflective mask blank characterized in that the layer in contact with the protective film in the above-described multilayer reflective film contains molybdenum (Mo).
2. In paragraph 1, A reflective mask blank characterized in that the above protective film is made of rhodium (Rh).
3. In paragraph 1, A reflective mask blank characterized in that the above protective film is composed of a layer containing rhodium (Rh) and ruthenium (Ru).
4. In paragraph 1, A reflective mask blank characterized in that the above protective film is composed of a layer containing rhodium (Rh) and a layer containing ruthenium (Ru).
5. A reflective mask blank characterized in that the etching blocking film is composed of niobium (Nb) or a niobium (Nb) compound containing niobium (Nb) and oxygen (O).
6. A method for manufacturing a reflective mask by manufacturing a reflective mask from a reflective mask blank described in claim 1 or 2.

Description

Reflective Mask Blank and Method for Manufacturing Reflective Mask The present invention relates to a reflective mask blank, which is a material for a reflective mask used in the manufacture of semiconductor devices such as LSIs, and a method for manufacturing a reflective mask from the reflective mask blank. In the manufacturing process of semiconductor devices (semiconductor equipment), photolithography technology is repeatedly used to transfer a circuit pattern formed on a transfer mask by irradiating it with exposure light and transferring it onto a semiconductor substrate (semiconductor wafer) via a reduction projection optical system. Conventionally, the wavelength of the exposure light has been 193 nm using an argon fluoride (ArF) excimer laser, and by adopting a process called multi-patterning, which combines the exposure process and the processing process multiple times, a pattern with dimensions smaller than the exposure wavelength has been formed. However, as the continuous miniaturization of device patterns has necessitated the formation of even finer patterns, EUV lithography technology has been utilized using extreme ultraviolet (hereinafter referred to as "EUV") light, which has a shorter wavelength than ArF excimer laser light, as the exposure light. EUV light is light with a wavelength of approximately 0.2 to 100 nm, more specifically, a wavelength of around 13.5 nm. Since EUV light has extremely low transmittance to materials, conventional transmissive projection optical systems or masks cannot be used, so reflective optical elements are utilized. For this reason, reflective masks are also used for pattern transfer. A reflective mask is formed by creating a multilayer reflective film that reflects EUV light on a substrate and forming a pattern of an absorption film that absorbs EUV light on the multilayer reflective film. Meanwhile, a state prior to patterning the absorption film (including a state in which a resist film is formed) is called a reflective mask blank, and this is used as a material for a reflective mask. A reflective mask blank generally has a basic structure comprising a low thermal expansion substrate, a multilayer reflective film that reflects EUV light formed on one of the two main surfaces of the substrate, and an absorption film that absorbs EUV light formed thereon. As a multilayer reflective film, a multilayer reflective film is typically used to obtain the necessary reflectance for EUV light by alternately stacking molybdenum (Mo) layers and silicon (Si) layers. Meanwhile, as an absorption film, tantalum (Ta), which has a relatively large decay coefficient value for EUV light, is used (Japanese Patent Publication No. 2002-246299 (Patent Document 1)). Additionally, as a protective film (capping film) to protect the multilayer reflective film during cleaning of the reflective mask, etc., a ruthenium (Ru) film or a rhodium (Rh) film, as disclosed in Japanese Patent Publication No. 2002-122981 (Patent Document 2) or Japanese Patent Publication No. 2005-516182 (Patent Document 3), is formed on the multilayer reflective film. In addition, as an etching mask when forming a pattern on the absorption film, a hard mask film containing chromium (Cr) may be formed on the absorption film. Meanwhile, a conductive film is formed on the main surface of the other side of the substrate. As for the conductive film, a metal nitride film is proposed for electrostatic chucking, and examples include films mainly containing chromium (Cr) and tantalum (Ta). FIG. 1 is a cross-sectional view showing an example (first aspect) of a reflective mask blank according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing another example (second aspect) of a reflective mask blank according to an embodiment of the present invention. FIG. 3 is a cross-sectional view showing an example of a reflective mask according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing another example (third aspect) of a reflective mask blank according to an embodiment of the present invention. The embodiments of the present invention will be described in more detail below. A reflective mask blank (100) has a substrate (1), a multilayer reflective film (2) that reflects exposure light formed on one main surface (surface) of the substrate (1), a protective film (3) formed on the multilayer reflective film (2), and an absorbing film (5) that absorbs exposure light formed above the protective film (3). Additionally, the reflective mask blank (100) has an etching stop film (4) between the protective film (3) and the absorbing film (5). The reflective mask blank (100) is suitable as a material for the reflective mask (110) (see FIG. 3) used in EUV lithography using EUV light as the exposure light. The wavelength of the EUV light used in EUV lithography using EUV light as the exposure light is 13 to 14 nm, and typically, it is light with a wavelength of about 13.5 nm