REFLECTIVE MASK BLANK FOR EUV LITHOGRAPHY

摘要

To provide an EUV mask blank which has an absorber layer having such a structure that the phase difference between a reflective layer and the absorber layer is in the vicinity of 180°, and the change of the phase difference between the reflective layer and the absorber layer is small to the film thick change of the absorber layer, and of which the absorber layer can be expected to be further thinner than a conventional absorber layer.;A reflective mask blank for EUV lithography, comprising a substrate, and a reflective layer for reflecting EUV light and an absorber layer for absorbing EUV light formed in this order on the substrate,
wherein the absorber layer consists of a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side,one of the upper layer and the lower layer of the absorber layer is a Cr film containing chromium (Cr) as the main component and containing at least one of oxygen (O) and nitrogen (N),the other is a TaPd film containing tantalum (Ta) and palladium (Pd) as the main components and containing at least one of oxygen (O) and nitrogen (N), andthe absorber layer satisfies the following conditions (1) to (5):(1) the total film thickness (L) of the absorber layer is at least 30 nm and at most 45 nm;(2) the film thickness of the TaPd film is at least 8 nm and at most 36 nm;(3) the peak reflectivity of the surface of the absorber layer to EUV light is at least 5% and at most 12%;(4) the phase difference (φ) between EUV reflected light on the surface of the reflective layer and EUV reflected light on the surface of the absorber layer, is within a range of 180°±10°; and(5) the gradient (Δφ/ΔL) of the change (Δφ) of the above phase difference (φ) to the change (ΔL) of the total film thickness (L) of the absorber layer is at most 15 deg/nm.

主权项

1. A reflective mask blank for EUV lithography, comprising a substrate, and a reflective layer for reflecting EUV light and an absorber layer for absorbing EUV light formed in this order on the substrate,
wherein the absorber layer consists of a layer (upper layer) on the surface side and a layer (lower layer) on the substrate side, one of the upper layer and the lower layer of the absorber layer is a Cr film containing chromium (Cr) as the main component and containing at least one of oxygen (O) and nitrogen (N), the other is a TaPd film containing tantalum (Ta) and palladium (Pd) as the main components and containing at least one of oxygen (O) and nitrogen (N), and the absorber layer satisfies the following conditions (1) to (5): (1) the total film thickness (L) of the absorber layer is at least 30 nm and at most 45 nm; (2) the film thickness of the TaPd film is at least 8 nm and at most 36 nm; (3) the peak reflectivity of the surface of the absorber layer to EUV light is at least 5% and at most 12%; (4) the phase difference (φ) between EUV reflected light on the surface of the reflective layer and EUV reflected light on the surface of the absorber layer, is within a range of 180°±10°; and (5) the gradient (Δφ/ΔL) of the change (Δφ) of the above phase difference ((φ) to the change (ΔL) of the total film thickness (L) of the absorber layer is at most 15 deg/nm.