	US 7,573,562 B2
	Reflective optical element and exposure apparatus
Seiji Kuwabara, Utsunomiya (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Mar. 26, 2008, as Appl. No. 12/55,844.
Claims priority of application No. 2007-086182 (JP), filed on Mar. 29, 2007.
Prior Publication US 2008/0247044 A1, Oct. 09, 2008
Int. Cl. G03B 27/54 (2006.01); G02B 1/10 (2006.01)

U.S. Cl. 355—67

3 Claims

1. An exposure apparatus comprising:

(A) an illumination optical system that illuminates a reticle with illumination light from a light source; and

(B) a projection optical system that includes a reflective optical element and projects a pattern of the reticle onto a member to be processed,

wherein the apparatus exposes the member to be processed with exposure light irradiated thereon via the projection optical system,

wherein the reflective optical element includes:

(a) a base member; and

(b) a dielectric multilayer film laminated on the base member, and

wherein the dielectric multilayer film includes, in an order from a base member side,

(i) a first multilayer group that is constituted by laminating at least four dielectric material layers, which includes at least two dielectric material layers having different refractive indices from each other and that has a first period length equivalent in optical film thickness, and

(ii) a second multilayer group that is constituted by laminating at least four dielectric material layers, which includes at least two dielectric material layers having different refractive indices from each other and that has a second period length equivalent in optical film thickness longer than the first period length equivalent in optical film thickness,

wherein, the dielectric multilayer films include a plurality of pairs of the first and second multilayer groups, and

wherein, when at least a part of light entering the reflective optical element has a wavelength range between 2 k_minλ₀/4 and 2 k_maxλ₀/4, specific multilayer groups that constitute the plurality of pairs of multilayer groups and have a period length equivalent in optical film thickness between k_minλ₀/4 and k_minλ₀/4 satisfy a condition in which the period lengths equivalent in optical film thickness of the specific multilayer groups are, in an order from a base member side specific multilayer group,

k₁λ₀/4<k₂λ₀/4< . . . k_iλ₀/4 . . . <k_nλ₀/4

where k_min≤k₁<k₂< . . . k_i. . . <k_n≤k_max,

1≤i≤n, n≧2,

k_nis a positive value, and

i is a positive integer.