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Multilayer mirror, method for manufacturing the same, and exposure equipment

A multi-layer film and reflector technology, which is applied in photolithography exposure devices, microlithography exposure equipment, semiconductor/solid-state device manufacturing, etc., can solve problems such as failure to reach

Inactive Publication Date: 2006-11-22
NIKON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In the case of non-absorbing layers, the peak reflectivity of the dielectric multilayer film gradually reaches 100%, however, it does not reach 100% in the EUV region due to absorption

Method used

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  • Multilayer mirror, method for manufacturing the same, and exposure equipment
  • Multilayer mirror, method for manufacturing the same, and exposure equipment
  • Multilayer mirror, method for manufacturing the same, and exposure equipment

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0126] figure 1 is a cross-sectional view of the multilayer film mirror according to the first embodiment of the present invention. The substrate 1 is made of low thermal expansion glass polished to a surface roughness of 0.2 nm RMS or less. Twenty pairs of Ru / Si multilayer films 3 are formed on the surface of the substrate 1 , and five pairs of Mo / Si multilayer films 5 are formed on the Ru / Si multilayer films 3 . The period length of the Ru / Si multilayer film 3 (the thickness of the unit periodic structure (film layer pair) of Ru / Si, is represented by d in the figure 11 Expressed) is 6.86nm, and the period length of Mo / Si multilayer film 5 (thickness of the film layer pair of Mo / Si, denoted by d in the figure 12 Expressed) is 6.9nm. The Γ value of these multilayer films in each unit periodic structure is 0.4. Note that the Γ value is the thickness of the Ru layer or Mo layer (d Ru or d Mo ) to the ratio of the period length (d) of the multilayer film (Γ=d Ru / d or Γ=d...

Embodiment 2

[0133] Figure 4 is a schematic cross-sectional view of a multilayer film mirror according to the second embodiment of the present invention. The substrate 10 is made of low thermal expansion glass polished to a surface (top surface in the figure) roughness of 0.2 nm RMS or less. Four pairs of Mo / Si multilayer films (deep film layer group) 11 are formed on the surface of the substrate 10 . The period length of the Mo / Si multilayer film 11 (the thickness of the Mo / Si film layer pair) was 6.9 nm, and the Γ value was 0.5.

[0134] On the surface of the Mo / Si multilayer film 11 is formed an additional layer 12 (a silicon layer in this embodiment). The thickness of the additional layer 12 is adjusted so as to have an optical thickness of about 1 / 4 of the wavelength of the incident light. In this embodiment, the thickness of the additional layer 12 is about 3.5 nm. In addition, on the surface of the additional layer 12, 20 pairs of Mo / Si multilayer films (surface film layer grou...

Embodiment 3

[0141] Image 6 is a schematic cross-sectional view of a multilayer film mirror according to a third embodiment of the present invention. The substrate 20 is made of low thermal expansion glass polished to a surface (top surface in the figure) with a roughness of 0.2 nm RMS or less. Five pairs of Ru / Si multilayer films (deep film layer group) 21 are formed on the surface of the substrate 20 . The period length of the Ru / Si multilayer film 21 (the thickness of the Ru / Si film layer pair) is 6.9 nm, and the Γ value is 0.5.

[0142] On the surface of the Ru / Si multilayer film 21 is formed an additional layer 22 (a silicon layer in this embodiment). The thickness of the additional layer 22 is adjusted to have an optical thickness of about 1 / 4 of the wavelength of the incident light. In this embodiment, the thickness of the additional layer 22 is about 3.85 nm. In addition, on the surface of the additional layer 22, 20 pairs of Ru / Si multilayer films (surface film layer groups) ...

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Abstract

A multilayer film reflection mirror intended to reduce the dependency of reflectance on an incident angle. A substrate (1) is made of a low-thermal-expansion glass polished until its surface (top surface in the FIG.) has a roughness of up to 0.2 nmRMS. An Ru / Si multilayer film (3) having the large half width of peak reflectance is formed on the surface of the substrate (1), and an Mo / Si multilayer film (5) having a high peak reflectance is formed on this Ru / Si multilayer film (3). Accordingly, a reflectance peak having a higher reflectance than the case with of Ru / Si only and a larger half width than the case with of Mo / Si multilayer film (5) only is obtained. Since Ru provides a larger EUV beam absorption than Mo, a higher reflectance than with the case of a structure in which the Ru / Si multilayer film (3) is formed on the Mo / Si multilayer film (5) is obtained. Since a multilayer film having a larger half width at a spectral reflectance has a smaller dependency of reflectance on an angle, the invention can keep a high imaging performance in a projection optical system.

Description

technical field [0001] The present invention relates to multilayer mirrors and the like used in EUV lithography, and more particularly, to techniques for reducing the dependence of reflectance on the surface of the mirror on the incident angle. Background technique [0002] At present, as a method of manufacturing semiconductor integrated circuits, reduced projection exposure capable of achieving a high processing speed is widely used. In this reduced projection technique, as semiconductor integrated circuit devices become finer, a projection lithography technique using soft X-rays having a wavelength of about 11 to 14 nm instead of ultraviolet rays has been developed (see Non-Patent Document 1). Recently, this technique is also referred to as EUV (Extreme Ultraviolet, Soft X-ray) lithography. The EUV lithography technology is expected to be a technology having a resolution of 45 nm or less, which is impossible with conventional lithography technology (wavelength of about 1...

Claims

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Application Information

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IPC IPC(8): H01L21/027G02B5/08G02B5/26G02B5/28G03F7/20G21K1/06
Inventor 神高典明村上胜彦小宫毅治白石雅之
Owner NIKON CORP
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