Undercut measurement using SEM

Details Undercut measurement using SEM Undercut measurement using SEM

2002-07-01

2003-12-30

Lee, John R. (Department: 2881)

Radiant energy

Inspection of solids or liquids by charged particles

Electron probe type

C250S307000, C250S311000

Reexamination Certificate

active

06670612

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to specimen inspection.
More particularly, the present invention relates to e-beam inspection systems.
2. Description of the Background Art
Semiconductor manufacturing processes include deposition and etching of various material layers on a semiconductor wafer. During the processing, various microscopic features (trenches, islands, and so on) are created on the wafer. Often times, the cross-sectional profile of a microscopic feature may be of interest to the manufacturer. In particular, the angle of undercut of a sidewall of the feature may be of interest.
Scanning electron microscopy (SEM) may be used to inspect a wafer, and the rock angle of the incident beam may be varied in an attempt to view an undercut. Unfortunately, SEM images tend to have significant resolution degradation when taken at large rock angles. This blurring of the images makes impractical the determination of large undercut angles by viewing SEM images at large rock angles.
Another conventional technique for determining undercut angles is by way of focus ion beam (FIB) sections. FIB systems impinge a focused beam on ions (for example, gallium ions) onto a specimen. The focused ion beam may act to precision mill the specimen at high beam currents or to image the specimen at low beam currents (in which case less material is sputtered). Hence, an FIB system may be used in preparing a cross-section specimen for transmission electron microscope (TEM) imaging. Recent FIB systems may be utilized for in-situ cross-section preparation and high-resolution imaging. However, FIB techniques are disadvantageously destructive due to the sputtering or milling of material from the sample.
FIG. 1A
is a conventional image of a cross section of a feature
170
that is slightly undercut on both left and right sides. The image of the cross section was obtained by the conventional focused ion beam (FIB) technique. As mentioned above, the FIB technique is disadvantageous in that it requires destruction of the specimen. This is because the FIB technique thins the sample by ion milling.
FIG. 1B
shows a conventional analysis of the cross-sectional FIB image of the feature
170
to determine the undercut angles. The analysis gives an outline of the feature
170
. Using the outline of the feature
170
, the undercut angle may be determined by comparing the actual left
172
-L and right
172
-R sidewalls to vertical reference lines
174
-L and
174
-R, respectively. (The slight asymmetry seen in the reference lines is thought to be due to the milling of the sample.) Analysis of this FIB image indicates a left undercut of about five (5) degrees and a right undercut of about two (2) degrees.


REFERENCES:
patent: 4426577 (1984-01-01), Koike et al.
patent: 5029250 (1991-07-01), Komatsu et al.
patent: 5578821 (1996-11-01), Meisberger et al.
patent: 5739909 (1998-04-01), Blayo et al.
patent: 5869833 (1999-02-01), Richardson et al.
patent: 6031614 (2000-02-01), Michaelis et al.
patent: 6054710 (2000-04-01), Bruggeman
patent: 6066849 (2000-05-01), Masnaghetti et al.
patent: 6411377 (2002-06-01), Noguchi et al.
patent: 6472662 (2002-10-01), Archie
patent: 2002/0151092 (2002-10-01), Li et al.
Focused Ion Beam Technology, IBM Microelectronics; Webpage [on-line], [retrieved on Oct. 17, 2002]. Retrieved from the internet: URL:http://www.-3ibm.com/chips/services/asg/capabilites/asweb13.html.

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