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Proceedings Paper

Overcoming low-alignment signal contrast induced alignment failure by alignment signal enhancement
Author(s): Byeong Soo Lee; Young Ha Kim; Hyunwoo Hwang; Jeongjin Lee; Jeong Heung Kong; Young Seog Kang; Bart Paarhuis; Haico Kok; Roelof de Graaf; Stefan Weichselbaum; Richard Droste; Christopher Mason; Igor Aarts; Wim P. de Boeij
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Paper Abstract

Overlay is one of the key factors which enables optical lithography extension to 1X node DRAM manufacturing. It is natural that accurate wafer alignment is a prerequisite for good device overlay. However, alignment failures or misalignments are commonly observed in a fab. There are many factors which could induce alignment problems. Low alignment signal contrast is one of the main issues. Alignment signal contrast can be degraded by opaque stack materials or by alignment mark degradation due to processes like CMP. This issue can be compounded by mark sub-segmentation from design rules in combination with double or quadruple spacer process. Alignment signal contrast can be improved by applying new material or process optimization, which sometimes lead to the addition of another process-step with higher costs. If we can amplify the signal components containing the position information and reduce other unwanted signal and background contributions then we can improve alignment performance without process change. In this paper we use ASML's new alignment sensor (as was introduced and released on the NXT:1980Di) and sample wafers with special stacks which can induce poor alignment signal to demonstrate alignment and overlay improvement.

Paper Details

Date Published: 15 March 2016
PDF: 7 pages
Proc. SPIE 9780, Optical Microlithography XXIX, 97800B (15 March 2016); doi: 10.1117/12.2220587
Show Author Affiliations
Byeong Soo Lee, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Young Ha Kim, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Hyunwoo Hwang, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Jeongjin Lee, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Jeong Heung Kong, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Young Seog Kang, SAMSUNG Electronics Co., Ltd. (Korea, Republic of)
Bart Paarhuis, ASML Netherlands B.V. (Netherlands)
Haico Kok, ASML Netherlands B.V. (Netherlands)
Roelof de Graaf, ASML Netherlands B.V. (Netherlands)
Stefan Weichselbaum, ASML Netherlands B.V. (Netherlands)
Richard Droste, ASML Netherlands B.V. (Netherlands)
Christopher Mason, ASML Netherlands B.V. (Netherlands)
Igor Aarts, ASML Netherlands B.V. (Netherlands)
Wim P. de Boeij, ASML Netherlands B.V. (Netherlands)

Published in SPIE Proceedings Vol. 9780:
Optical Microlithography XXIX
Andreas Erdmann; Jongwook Kye, Editor(s)

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