EUV mask defect detection system and method

Abstract

The invention discloses an EUV mask defect detection system and method. The EUV mask defect detection system comprises an extreme ultraviolet light beam which obliquely enters the surface of a to-be-detected mask, a reflection cup which is used for collecting and reflecting scattered light caused by surface defects of the mask to be detected, a transmission part which is used for transmitting thereflected light emitted by the reflection cup, and a detector which is used for receiving the optical signal transmitted by the transmission part and acquiring the surface defect information of the mask to be detected. According to the design of the invention, the extreme ultraviolet light beam is obliquely emitted into the mask to be detected, and the reflection cup is allowed to be closer to thesurface of the mask to be detected as a collection part, so that the NA of the collection part is increased, and the scattered light collection efficiency caused by defects is improved.

Description

technical field [0001] The present invention relates to the technical field of EUV lithography, and in particular to an EUV mask defect detection system and method. Background technique [0002] Defect-free EUV (extremely ultraviolet) mask preparation is one of the key issues restricting EUV lithography to mass production. Therefore, EUV mask defect detection is the key core technology to realize EUV lithography. EUV mask defects can be divided into amplitude type defects and phase type defects, among which phase type defects are the most important defects because their existence cannot be repaired. Phase defects are also the most studied defects. Because the phase defect is caused by the distortion of the multi-layer structure of the EUV mask, it needs to penetrate the multi-layer structure for detection, and the traditional detection method based on deep ultraviolet or ultraviolet cannot meet this requirement. [0003] To this end, researchers use the actinic method, th...

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Problems solved by technology

[0004] On the one hand, the disadvantage of this method is that due to the existence of the plane mirror, the curved mirror cannot be too close to the reticle for defect detection, which limits the receiving NA (numerical aperture) of scattered light from defects. NA must increase the size of the curved mirror. The increase in the size of the curved mirror increases the processing difficulty of the curved mirror on the one hand, and increases the processing cost on the other hand; on the other hand, when the defect is small, the defect scatter light When the signal is equal to the noise, it is difficult for the system to detect defects due to the degradation of the signal-to-noise ratio

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