Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1997-08-06
2001-11-20
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754120, C324S765010
Reexamination Certificate
active
06320396
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a parasitic MIM (metal/insulator/metal) structural spot analysis method for a semiconductor device and a parasitic MIM structural spot analysis method for a Si semiconductor device, which are suitable for inspections of failures of wirings on a semiconductor integrated circuit chip and for inspection of failures of a wiring system such as vias and contact holes.
2. Description of the Related Art
For a conventional failure detection and analysis method for a semiconductor device such as a semiconductor integrated circuit, which is an object of the present invention, there have been, for example, Japanese Patent Application Laid Open No. 6-300824 (hereinafter, referred to as reference 1), Nikawa, K., C. Matsumoto, and S. Inoue, “Verification and Improvement of the Optical Beam Induced Resistance Variation (OBIRCH) method”, Proc. International Symposium for testing and Failure Analysis, pp. 11-16 (1994) (hereinafter, referred to as reference 2) (both references 1 and 2 are hereinafter referred to as prior art 1), Koyama, T., Mashiko, M. Sekine, H. Koyama and K. Horie, “New non-bias optical beam induced current technique for evaluation of Al interconnects”, Proc. IRPS, pp. 228-233 (1995) (hereinafter, referred to as reference 3), and Mashiko, Y., T. Koyama, and H. Koyama, Proc. 6th European Symp. Rel. Electron Devices, Failure Phys. And Analysis, pp 293-298 (1995) (hereinafter, referred to as reference 4) (both references 3 and 4 are hereinafter referred to as prior art
2
).
Apparatuses of prior art 1 and 2 have a common constitution.
FIG. 1
shows a constitution of an inspection apparatus for a semiconductor device disclosed in these references. On a sample stage
111
an integrated circuit
116
is mounted as a sample. Laser beam
119
emitted from a laser beam generation section
113
is incident on a microscope section
114
, and is irradiated onto a chip of the integrated circuit
116
after being converged. A constant power source
115
, a current variation detection section
117
and a test pattern generation section
118
are connected to the sample stage
111
. The test pattern generation section
118
serves to generate test patterns for setting the integrated circuit
116
to a specific state, onto which the laser beam
119
is irradiated. The constant power source
115
, the current variation detection section
117
and the test pattern generation section
118
, which are connected to the sample stage
111
, are electrically connected to corresponding pins of the integrated circuit
116
.
The microscope section
114
, the constant power source
115
, the current variation detection section
117
and the test pattern generation section
118
are connected to a system controlling/signal processing section
121
for controlling the whole system and for processing an acquired signal. The system controlling/signal processing section
121
is designed so as to perform a predetermined control operation and signal processing. An image display section
122
is formed of a CRT, which is connected to the system controlling/signal processing section
121
. The image display section
122
is designed such that an image as a result of processing of the acquired signal is displayed thereon.
According to the prior failure detection/analysis method for a semiconductor device, the laser beam is irradiated onto a region of the integrated circuit
116
to be detected while scanning the laser beam thereon. Then, an increase in resistance which is caused by an increase in temperature due to an increase in the irradiation light (the prior art 1), and a generation of a thermally generated emf (the prior art 2) are detected as a current variation using the current variation detection section
117
. Subsequently, for example, in synchronization with scanning of the light beam
119
, variations in the current flowing through the wiring to be detected are displayed on the image display section
122
in the form of variations in luminance or in the form of pseudo colors which are obtained by converting the luminance thereto for convenience, the variations corresponding to every irradiated position. Thus, detection of a void more than 0.1 &mgr;m in the wiring (the reference 2), a void more than 0.5 &mgr;m in the wiring (the reference 3) and a parasitic interposition layer of about 50 nm between a via and a wiring (the reference 4) are possible.
A principle for detecting them will be briefly described. First, a principle of the prior art 1 will be described. It is assumed that a variation in a current due to a temperature increase at the time of irradiation of beam onto the portion of a wiring in an integrated circuit is &Dgr;I. Assuming that a constant voltage is applied to opposite ends of the wiring and the system is connected in series to the wiring, the variation &Dgr;I in the current is approximated by the following equation (1),
&Dgr;I≈−(&Dgr;R/R)I (1)
where R is a resistance obtained by summing up the resistance of the wiring and the resistance of the system connected in series to the wiring, at the time when no beam is irradiated thereon, and &Dgr;R is a variation of the resistance of the wiring due to the beam irradiation. Moreover, I is a current flowing through the wiring at the time when no beam is irradiated.
Since the resistance R is constant if the wiring to be observed and the system connected in series thereto are decided, the product of the variation &Dgr;R of the resistance and the current I can be obtained by measuring the variation &Dgr;I of the current, as long as other conditions are kept constant. Moreover, when the current I is made constant, the rate of variation &Dgr;R of the resistance in each portion of the wiring can be detected. Detailed description about it will be made as follows.
This is disclosed in the references 1 and 2 as a detection method of defects such as voids and Si precipitation. Specifically, if beam conditions, materials of the irradiated portions and shapes are the same, the ratios of variation &Dgr;R of the resistance in each portion differ only depending on a thermal conductivity thereof. If there are defects such as voids and Si precipitation in the wiring, the thermal conductivity differs. It has been experimentally confirmed that the difference of the ratio of variation &Dgr;R of resistance can be observed by virtue of this effect. Since the voids and Si precipitation in the wiring are important as factors to decide reliability of the integrated circuit, this effect has importance. For sizes of the voids to be detected according to this method, the ones having the minimum size of 0.1 &mgr;m are disclosed in the reference 2. At this time, in order to verify the existence of voids of about 0.1 &mgr;m, an SIM (scanning type ion microscope) is used. This method is called an OBIRCH method (an Optical Beam Induced Resistance Change method).
Effectiveness of a method called a NB-OBIC method (a Non-Bias Optical Beam Induced Current method) (the prior art 2) utilizing a thermoelectric effect by laser beam heating on detection of failures such as voids of the wiring system (the reference 3) is also disclosed as a method using beam heating. This NB-OBIC method differs from the OBIRCH method only in that no voltage need be applied to the integrated circuit to be observed, and others are the same as the OBIRCH method. It should be noted that the NB-OBIC method described later can not be principally used for observation of the current unlike the OBIRCH method. The principle of the NB-OBIC method is explained as follows. Specifically, when defects exist in the wiring system, the thermal conductivity of the portions of the defects differs from the positions other than the defects. Or, the thermal conductivity state differs because of existence of the defects. Therefore, a temperature gradient is produced, resulting in production of thermally generated emf. The thermally generated emf is detected as the current. It has been disclosed in the reference 3 th
Hollington Jermele M.
Metjahic Safet
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
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