US 6,441,963 B2 · Multi-layered mirror

Abstract

A multi-layered mirror has a substrate, a first layer of a first substance, a second layer of a second substance. The refractive index of the first substance in a utilized wavelength region is different from that of the second substance. The first and second layers are laminated alternately on the substrate. To obtain a high reflectivity and superior optical characteristics, a multi-layered structure is formed within either the first layer or the second layer using at least two substances whose real parts of the complex indices of refraction in the utilized wavelength region are approximately the same. Alternatively, a layer surface is smoothed before forming a next layer thereon. An exposure apparatus that uses multi-layered mirrors of the present invention uses light with higher efficiency.

Drawings

Claims15

Dependent claims

A multi-layered mirror comprising:

a substrate;
at least one first layer of a first substance with a small refractive index;
and
at least one second layer of a second substance with a large refractive index,
wherein the at least one first layer and the at least one second layer are alternately laminated on the substrate by sputtering, and
wherein an interface between the at least one first and the at least one second layers of the multi-layered mirror has been irradiated by an ion beam and smoothed so that for d>5 nm, σint−σsub<0.2 nm, and for d<5 nm, σint−σsub<0.5 nm, where d is a periodic length defined as a sum of the first substance layer thickness and the second substance layer thickness, σsub is an RMS value of surface roughness of the substrate, and σint is an RMS value of roughness of the interface.

3 more elements

Dependencies are inferred from the claim text.

Description13,536 words

Summary2,401 words

#1. Field of the Invention

#The present invention relates to a multi-layered mirror, a manufacturing method thereof, a stress control method thereof, and an exposure apparatus. More particularly, the present invention relates to a multi-layered mirror for X-rays or neutrons, such as X-ray apparatus including X-ray telescopes, X-ray lasers, and soft X-ray projection lithography.

#2. Description of the Related Art

Brief description of the drawings15 figures

#The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention in the drawings:

#FIGS. 1(a) and (b) are cross-sectional diagrams of one embodiment of a multi-layered mirror of the present invention;

#FIGS. 2(a) and 2(b) and 2(c) are explanatory drawings of one example of a method of manufacturing a multi-layered mirror by irradiation using a particle beam P during multi-layered film formation stage;

Detailed description10,741 words

#Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

#It is known that substrate deformation becomes a problem due to internal stress of a multi-layered film when a Mo/Si multi-layered film is used as a mirror. It is also known that this internal stress can be lowered by increasing the number of layers while maintaining a fixed total film thickness of a multi-layered film and by decreasing the film thickness of each layer. (W. Wasa, S. Miwa, and K. Murakami, Internal Stress of a Mo/Si Multi-Layered Film, 56th Collection of Lecture Preprints of the Japan Society of Applied Physics, Vol.2, 1995). Using the method of increasing the number of layers by reducing thicknesses of various films, the periodic length (in case of a Mo/Si multi-layered film, the thickness of a pair of layers comprising an adjacent Mo and Si layers) of a multi-layered film decreases. Thus, this method can not be applied to a multi-layered mirror with a designated utilized wavelength.

#In the present invention, internal stress is lowered without altering a periodic length of a multi-layered film. The following two methods are used to decrease internal stress of a multi-layered film: (1) a first method increases the number of interfaces of the multi-layered film by replacing an arbitrary layer (of a certain substance) of the multi-layered film with a multiple layer including the certain substance and a substance with the same δ optical constant as that of the certain substance; (2) a second method irradiates the layer surface with a particle beam as a multi-layered film is formed.

Facts

Application

09/867,191Filed 30 May 2001 · division

Priority

JP 10-2534848 Sep 1998

Published

US 2001/0033421 A125 Oct 2001

Granted

27 Aug 2002

Term ended

8 Sep 2019

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification7 codes

G03F 7/70058
Microphotolithographic exposure; Apparatus therefor: mask illumination systems
B82Y 10/00
Nanotechnology for information processing, storage or transmission
G03F 7/70233
Mask projection systems: optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection…
G21K 1/062
Using diffraction, refraction or reflection, e.g. monochromators: devices having a multilayer structure

Multi-layered mirror

Life of this patent

Multi-layered mirror

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims15

Description13,536 words

Drawings

Classification7 codes

Life of this patent

Description13,536 words