WD=0"minimizes the effect of lens aberrations, and maximizes the resolving power. Innovative designs to achieve WD=0 are as follows: (1)A large objective lens of 730-mm width
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High-Resolution Wafer Inspection Using the "in-lens SEM"
Fumio MIZUNO Satoru YAMADA Tadashi OHTAKA Nobuo TSUMAKI Toshifumi KOIKE
IEICE TRANSACTIONS on Electronics Vol.E79-C No.3 pp.317-323
Publication Date: 1996/03/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Scientific ULSI Manufacturing Technology)
Category: Particle/Defect Control and Analysis
semiconductor devices, wafer inspection, scanning electron microscope, objective lens, eucentric stage, acoustic motor, spatial resolution, line-width measurement, BEASTLI,
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A new electron-beam wafer inspection system has been developed. The system has a resolution of 5 nm or better, and is applicable to quarter-micron devices such as 256 Mbit DRAMs. The most remarkable feature of this system is that a specimen stage is built in the objective lens and allows a working distance (WD) of 0. "WD=0"minimizes the effect of lens aberrations, and maximizes the resolving power. Innovative designs to achieve WD=0 are as follows: (1)A large objective lens of 730-mm width 730-mm depth 620-mm height that serves as a specimen chamber, has been developed. (2)A hollow specimen stage made of non-magnetic materials has been developed.It allows the lower pole piece and magnetic coile of the objective lens inside it. (3)Acoustic motors made of non-magnetic materials are em-ployed for use in vacuum.