Growth and printability of multilayer phase defects on extreme ultraviolet mask blanks

Abstract

Articles you may be interested inLevel-set multilayer growth model for predicting printability of buried native extreme ultraviolet mask defects Influence of shield roughness on Mo/Si defect density for extreme ultraviolet lithography mask blanksThe ability to fabricate defect-free reflective Mo-Si multilayer ͑ML͒ blanks is a well-recognized challenge in enabling extreme ultraviolet ͑EUV͒ lithography for semiconductor manufacturing. Both the specification and reduction of defects necessitate the understanding of their printability and how they are generated and grow during ML deposition. A ML phase defect can be depicted by its topographical profile on the surface as either a bump or pit, which is then characterized by height or depth and width. These phase defects are complex in nature and their impact to resist printing. The authors developed an effective way to study phase defects with programmed defect mask ͑PDM͒ as "model" test vehicle. The defects are produced with tuned ML deposition process and placed in varying proximity to absorber patterns on the mask. This article describes the recent study of ML phase defect printability from exposures of a ML PDM on the EUV microexposure tool with annular, monopole, and dipole illuminations.

Improved oxidation resistance of Ru/Si capping layer for extreme ultraviolet lithography reflector

“…The deposition of each capping layer is conducted by magnetron sputtering in the CXRA ͑The Center for X-ray Optics͒ group. 3 Alternating ultrathin layers of each material ͑0.2 nm of silicon, boron, and carbon and 0.4 nm of ruthenium͒ were deposited for better intermixing of the bilayers. Three thick capping layers ͑ϳ50 nm thick͒ of Ru, Ru/Si, or Ru/B on 2 in.…”

“…The highest reflectivity rate ͑ϳ70%͒ has been achieved by using 40 Si/Mo multilayers with a period of 6.8 nm, half of the EUV wavelength ͑13.5 nm͒. [1][2][3][4] Because of the high oxidation reactivity of the top Si layer, the EUV mirror is covered with a thin 2-3 nm Ru layer on stacked Si/Mo multilayers. Ru capping layers have been utilized for their optical properties ͑high transmission coefficient at 13.5 nm͒ and high chemical resistance in many corrosive environments.…”

Enhancing defect detection with Zernike phase contrast in EUV multilayer blank inspection

“…Although for convenience we often separately consider phase and absorber defects, in reality true defects are almost always a combination of the two types under inspection [4,5]. To address this fact, we consider the effectiveness of the Zernike phase contrast method in the presence of such real world "blended" defects.…”

“…The test sample for the experiment is a programmed defect mask [5]. The substrate defects are defined by e-beam lithography using a 48 nm thick hydrogen silsesquioxane (HSQ) resist with a square shape on a quartz substrate.…”

Phase measurements of EUV mask defects

“…These programmed defects have previously been studied using various techniques. [7][8][9] They consist of squares of fixed height and varied width patterned onto the substrate before multilayer deposition. We imaged the defects using σ = 0.25 monopole illumination, an NA of 0.0825, and wavelength of 13.5 nm.…”