A new method for the actinic inspection of defects inside and on top of extreme ultraviolet (EUV) lithography multilayer-coated mask blanks is presented. The experimental technique is based on photoemission electron microscopy supported by the generation of a standing wave field inside and above the multilayer mask blank when illuminated near the resonance Bragg wavelength at around 13.5nm. Experimental results on programed defect samples based on electron beam lithographic structures or silica balls overcoated with an EUV multilayer show that buried defects with a lateral size down to 50nm are detectable. Furthermore, phase structures as shallow as 6nm in height on a programed phase grating sample have been detected by this technique. The contrast of the phase defect structures has shown to be strongly dependent on and controlled by the phase of the standing wave field at the mask blank surface, and thus can be optimized by tuning the inspection wavelength.

1.
P.
Naulleau
 et al.,
J. Vac. Sci. Technol. B
21
,
1286
(
2003
).
2.
International Technology Roadmap for Semiconductor, see www.itrs.org
3.
Y.
Liu
,
A.
Barty
,
E. M.
Gullikson
,
J. S.
Taylor
,
J. A.
Liddle
, and
O.
Wood
,
Proc. SPIE
5751
,
660
(
2005
);
Y.
Tezuka
,
M.
Ito
,
T.
Teresawa
, and
T.
Tomie
,
Proc. SPIE
5567
,
791
(
2005
).
4.
K.
Kinoshita
,
T.
Haga
, and
K.
Hanamoto
,
J. Vac. Sci. Technol. B
22
,
264
(
2004
).
5.
M.
Yi
,
T.
Haga
,
C.
Walton
,
C.
Larson
, and
J.
Borkor
,
Jpn. J. Appl. Phys., Part 1
41
,
4101
(
2002
).
6.
M.
Park
,
M.
Yi
,
P.
Mirkarimi
,
C.
Larson
, and
J.
Bokor
,
J. Vac. Sci. Technol. B
20
,
3000
(
2002
).
7.
G.
Schonhense
and
U.
Kleineberg
, German Patent No. DE 100 32 979 A1 (17 January
2002
).
8.
U.
Neuhäusler
 et al.,
Appl. Phys. Lett.
88
,
053113
(
2006
).
9.
U.
Neuhäusler
,
J.
Lin
,
A.
Oelsner
,
M.
Schicketanz
,
J.
Slieh
, and
N.
Weber
,
Microelectron. Eng.
83
,
680
(
2006
).
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