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Refilled mask structure for minimizing shadowing effect on EUV Lithography

Title
Refilled mask structure for minimizing shadowing effect on EUV Lithography
Author
신현덕
Advisor(s)
안진호
Issue Date
2010-02
Publisher
한양대학교
Degree
Master
Abstract
13.5 nm 파장의 빛을 사용하는 극자외선 노광기술은 32 nm 선폭 이하의 생산공정의 주류가 될 것으로 예상되고 있다. 극자외선 노광기술의 주된 문제점 중에 하나는 shadowing effect이다. Mask shadowing은 다층박막 구조와 빛의 사입사로 생기는 독특한 현상이다. 이로 인하여 H-V CD bias와 contact hall에서 ellipticity를 발생시킨다. Shadowing effect를 최소화 하기 위해서는 refilled mask가 하나의 선택사항이 될 수 있다. Refilld mask 구조의 개념은 먼저 다층박막을 부분 etching하고 trench를 다시 TaN 흡수체로 채우는 것이다. 모든 시뮬레이션은 pre-production tool 조건에서 32 nm pattern 크기의 refilled mask 구조의 적용 가능성을 확인하기 위해서 EM-Suite 시뮬레이션 tool을 사용하였다. Side wall 각도에 따른 image contrast와 H-V CD bias를 평가하였으며 refilled depth에 따른 aerial image, H-V CD bias, process window를 평가하였다. 마지막으로 shadowing effect를 최소화하기 위한 refilled depth는 etched depth 보다 작다는 것을 확인하였다.
Extreme ultraviolet (EUV) lithography using 13.5 nm wavelengths is expected to be adopted as a mass production technology for 32 nm half pitch and below. One of the new issues introduced by EUV lithography is the shadowing effect. Mask shadowing is a unique phenomenon caused by using mirror-based mask with an oblique incident angle of light. This results in a horizontal-vertical (H-V) biasing effect and ellipticity in the contact hole pattern. To minimize the shadowing effect, a refilled mask is an available option. The concept of refilled mask structure can be implemented by partial etching into the multilayer and then refilling the trench with an absorber material. The simulations were carried out to confirm the possibility of application of refilled mask in 32 nm line-and-space pattern under the condition of pre-production tool. The effect of sidewall angle in refilled mask is evaluated on image contrast and measured critical dimension (CD) on the wafer. We also simulated the effect of refilled depth on aerial image, H-V CD bias, and overlapping process window. Finally, we concluded that the refilled depth for minimizing shadowing effect should be thinner than etched depth.
URI
http://dcollection.hanyang.ac.kr/jsp/common/DcLoOrgPer.jsp?sItemId=000000056449https://repository.hanyang.ac.kr/handle/20.500.11754/143101
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > NANOSCALE SEMICONDUCTOR ENGINEERING(나노반도체공학과) > Theses (Master)
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