Reflective photomask blank, reflective photomask, and method for manufacturing semiconductor device using same
A photomask blank, reflective technology, applied in semiconductor/solid-state device manufacturing, photoengraving process of patterned surface, originals for photomechanical processing, etc., can solve problems such as the reduction of reflectivity of multilayer reflective films
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Embodiment 1
[0105] 10 to 13 are schematic cross-sectional views showing manufacturing steps of an example of the reflective photomask according to the first aspect of the present invention.
[0106] First, the multilayer reflective film 2, the buffer layer 3, the first light-absorbing layer 41, and the second light-absorbing layer 42 are sequentially formed on the substrate 1 as follows to prepare the reflection-type light absorbing layer of the present invention having the same structure as that of FIG. Mask blank 10 .
[0107] As the substrate 1 , a synthetic quartz having an outer shape of 6 inches square and a thickness of 0.25 inches having a flat surface formed by polishing the surface was prepared.
[0108] On the substrate 1, Mo and Si are alternately laminated for about 40 cycles by DC magnetron sputtering, thereby preparing a multilayer reflective film 2 with the maximum reflectance to EUV light in the wavelength range of 13 to 14 nm. In addition, the multilayer reflective film...
Embodiment 2
[0124] Another example of the reflective photomask blank of the first viewpoint was prepared in the same manner as in Example 1, except that the film-forming time by sputtering was longer than in Example 1, and a second light-absorbing layer having a film thickness of 20 nm was formed.
[0125] The spectral reflectance of the uppermost surface of the light-absorbing laminated layer 4 of the obtained reflective photomask blank was measured in the same manner as in Example 1.
[0126] As a result, it was 8.85% at a wavelength of 193nm and 1.93% at a wavelength of 257nm. In this case, a sufficient low reflectance characteristic was obtained particularly in the 257nm inspection DUV light wavelength region.
[0127] Then, using this reflective photomask blank, the preparation of a reflective photomask was carried out in the same manner as in Example 1, and Cl 2 After dry etching with He mixed gas atmosphere, and Cl 2 and O 2 Measurement of reflectance at 257nm inspection waveleng...
Embodiment 3
[0134] In the same manner as in Example 1, a multilayer reflective film and a first light-absorbing layer were formed on the substrate.
[0135] Then, using Ta and Si targets, the Ar / O 2 = 36 / 4 (sccm) mixed gas atmosphere, under the gas pressure of 0.25Pa, apply DC power of 60W and 240W to Ta target and Si target, respectively, thereby forming TaSi-based oxide with a thickness of 27nm by binary sputtering membrane. At this time, the surface roughness of the upper absorber layer after film formation was 0.42 nmRms, and had good surface smoothness. In addition, the composition ratio of the produced TaSi-based oxide film is: Ta is 33at%, O 2 is 36at%. The measurement results of the spectral reflectance of the outermost surface of the obtained light-absorbing laminate are shown in FIG. 15 . It was 2.55% at a wavelength of 193nm and 1.51% at a wavelength of 257nm, and sufficient low reflection characteristics were obtained in the wavelength region of DUV light for inspection. ...
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Abstract
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