Filtered e-beam inspection and review

Details Filtered e-beam inspection and review Filtered e-beam inspection and review

2003-06-26

2004-09-28

Lee, John R. (Department: 2881)

Radiant energy

Inspection of solids or liquids by charged particles

Electron probe type

Reexamination Certificate

active

06797955

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to specimen inspection and review. More particularly, the present invention relates to abeam inspection and systems.
2. Description of the Background Art
Automated inspection and review systems are important in process control and yield management for the semiconductor and related microelectronics industries. Such systems include optical and electron beam (e-beam) based systems.
An example of an e-beam apparatus for an inspection or review system is described in U.S. Pat. No. 5,578,821, issued to Meisberger et al (the Meisberger patent). The disclosure of the Meisberger patent is hereby incorporated by reference in its entirety.
FIG. 1
(corresponding to
FIG. 5
in the Meisberger patent) is a simplified schematic representation of the paths of the primary, secondary, back-scatter and transmitted electrons through the electron column and collection system for electron beam inspection. In brief,
FIG. 1
shows a schematic diagram of the various electron beam paths within the column and below substrate
57
. Electrons are emitted radially from field emission cathode
81
and appear to originate from a very small bright point source. Under the combined action of the accelerating field and condenser lens magnetic field, the beam is collimated into a parallel beam. Gun anode aperture
87
masks off electrons emitted at unusable angles, while the remaining beam continues on to beam limiting aperture
99
. An upper deflector (not depicted) is used for stigmation and alignment, ensuring that the final beam is round and that it passes through the center of the objective lens
104
comprising elements
105
,
106
and
107
. A condenser lens (not depicted) is mechanically centered to the axis defined by cathode
81
and beam limiting aperture
99
. The deflection follows the path shown, so that the scanned, focused probe (beam at point of impact with the substrate) emerges from the objective lens
104
. In High Voltage mode operation, Wien filter deflectors
112
and
113
deflect the secondary electron beam into the secondary electron detector
117
. When partially transparent masks are imaged, the transmitted beam
108
passes through electrode system
123
and
124
that spreads the beam
108
before it hits the detector
129
. In Low Voltage mode operation, the secondary electron beam is directed by stronger Wien filter deflections toward the low-voltage secondary electron detector
160
that may be the same detector used for backscatter imaging at high voltage. Further detail on the system and its operation is described in the Meisberger patent.
There are also other types of e-beam tools for inspection or review. For instance, another type is described in U.S. Pat. No. 5,973,323, issued to Adler et al (the Adler patent). The disclosure of the Adler patent is hereby incorporated by reference in its entirety. The Adler patent discloses a Secondary Electron Emission Microscope (SEEM). The SEEM is an example of a projection type system, where the e-beam impinges upon a relatively large region, and scattered electrons from the region are imaged onto a two-dimensional detector.


REFERENCES:
patent: 5493116 (1996-02-01), Toro-Lira et al.
patent: 5578821 (1996-11-01), Meisberger et al.
patent: 5973323 (1999-10-01), Adler et al.
patent: 6038018 (2000-03-01), Yamazaki et al.
patent: 6232787 (2001-05-01), Lo et al.
patent: 6317514 (2001-11-01), Reinhorn et al.
patent: 6583414 (2003-06-01), Nozoe et al.
patent: WO 96/08835 (1996-03-01), None
A. Khurseed, et al “An add-on secondary electron energy spectrometer for scanning electron microscopes” Mar. 2001 American Institute of Physics, pp. 1708-1714, vol. 72, No. 3; Singapore.

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