Mask blank and photomask

Abstract

The invention relates to a mask blank and a photomask. The mask blank has a mask layer serving as a photomask. The mask blank is low in reflectivity and has specified optical density, the etching rateof a shading layer can be close to the etching rate of an anti-reflection layer, and an appropriate section shape capable of reducing an upper eave and a lower hem can be achieved. The mask layer has: a lower anti-reflection layer laminated on a transparent substrate; a shading layer provided at a position farther away from the transparent substrate than the lower anti-reflection layer; and an upper anti-reflection layer provided at a position farther away from the transparent substrate than the shading layer.

Description

technical field [0001] The invention relates to a mask blank and a photomask, in particular to a technique suitable for use in the manufacture of a double-sided low-reflection binary mask blank or a binary mask blank. Background technique [0002] When manufacturing a photomask for a large panel such as a flat panel display (FPD), a mask blank with a light-shielding layer is used as a binary mask. In addition, along with the high-definition of FPD, the necessity of forming a fine pattern is increasing. [0003] In such a mask blank, a structure in which a film made of a chromium material is laminated on a transparent substrate such as glass is generally used as a mask layer including a patterned light-shielding layer and the like (Patent Document 1). [0004] In order to produce fine patterns, it is necessary to achieve low reflectance (for example, reflectance under exposure light with a wavelength of 436nm of 5% or less) on the front and back surfaces of the mask blank as...

AI Technical Summary

Problems solved by technology

[0008] However, the etch rate of chromium oxide film with high oxygen concentration decreases

As a result, when a chromium oxide film with a high oxygen concentration is used as the antireflection layer, since the etching rate of the antireflection layer is lower than that of the light shielding layer, the etching of the antireflection layer may not progress.

[0009] Therefore, when making a mask pattern, the etching of the light-shielding layer progresses compared with the antireflection layer, and the amount of lateral etching in the mask blank, that is, the amount of side etching becomes uneven in the thickness direction.

Specifically, it was found that there is a problem that the central part in the thickness direction of the mask layer is etched in a large amount unnecessarily, resulting in a cross-sectional shape in which the upper eaves (shroud) and the hem (壳引き) are formed, etc.

Therefore, the etching rate difference between the light-shielding layer and the anti-reflection layer is larger

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