JPH10170612A - Method and device for inspecting internal mutual wiring in semiconductor integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect defects of internal mutual wiring in semiconductor integrated circuit quickly and non-destructively. SOLUTION: In the condition where electric current is supplied on a semiconductor integrated circuit chip 1 from a voltage supplying source 9, narrowed laser light is scanned and radiated on the chip 1, and a variable current detecting/amplifying component 8 detects a part where current changes largely. Because the part with large current change detected by the variable current detecting/amplifying component 8 is corresponding to the part where heat conduction is disturbed, defects such as void are detected. Based on this principle, even a defect which is not exposed on the surface can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting a defect on a semiconductor integrated circuit chip, and more particularly to a method for inspecting a defect of an internal interconnection on a semiconductor integrated circuit chip by using a laser beam, an electron beam or an ion beam. And devices.

[0002]

2. Description of the Related Art Conventionally, this type of defect "inspection method and apparatus" (hereinafter abbreviated as "method" only) is described, for example, in "W., Lee Smith et. Al.," Dir.
ectmeasurement of stress-
induced voidby by the
rmal wave modulated optic
al reflection imaging ", 1
990 IRPS (IEEE), 200-208, (19
90). As shown in ", two types of laser beams are used, a probe is made with one laser beam, and a detection is made with the other beam.

FIG. 3 is a diagram showing an example (first conventional example) of a conventional method for inspecting a defect of an internal interconnection on a semiconductor integrated circuit chip using a laser beam. The sample 26 is generated by the probe laser 21 from the probe laser generator 19.
Probe. On the other hand, from the pump laser generator 18,
The sample 26 is irradiated with a laser 20 having a change in intensity called a pump laser, and a change in the reflectance generated on the sample as a result is detected by the thermal wave signal detector 22 as a change in the reflectance of the probe laser 21.

[0004] In the figure, reference numeral 24 denotes a time change of the probe laser intensity, 23 denotes a time change of the pump laser intensity,
25 shows the detection of the reflectance by the thermal wave signal.

There is also a method for inspecting a defect in a semiconductor sample using a laser beam (second conventional example). As shown in FIG. 4, a semiconductor sample 27 to which a voltage is applied by the voltage supply source 9 is irradiated with a laser beam 17, and as a result, electrons generated inside the semiconductor are exposed.
A hole pair (electrons 28, holes 29) is to be detected as a change in current, and an OBIC (optical bead) is detected.
It is well known as the am induced current method.

[0006]

In the conventional defect detection method described with reference to FIG. 3, it is necessary to use two lasers, and the two laser beams are irradiated to the same spot with an accuracy of the order of μm to sub-μm. Therefore, the laser beam cannot be directly scanned, and the sample stage must be scanned. Therefore, there is a problem that it takes time to scan, and it takes time to acquire an image.

The conventional OBIC method described with reference to FIG.
It does not disclose that the sample is a semiconductor or a substance containing a semiconductor and that a metal is the target substance.

It is an object of the present invention to provide an inspection method and apparatus capable of scanning an irradiation laser itself and detecting a defect of an internal interconnection of a semiconductor integrated circuit in a short time without destruction.

[0009]

According to the present invention, there is provided a method for inspecting internal interconnections of a semiconductor integrated circuit, the method comprising: applying irradiation current to a semiconductor integrated circuit while scanning a laser beam while applying a current to the internal interconnections of the semiconductor integrated circuit; Then, a change in a current flowing through the internal interconnection, which is caused by an increase in wiring resistance due to a rise in temperature due to irradiation, is detected. At a defective portion, heat conduction is deteriorated, and the resistance of the wiring is increased from a position without a defect. In this case, the defect of the internal interconnection is detected by increasing the current change.

According to the present invention, there is provided an apparatus for inspecting internal interconnections of a semiconductor integrated circuit, comprising: means for supplying a current to the internal interconnections of the semiconductor integrated circuit; and laser beam irradiation heating for irradiating and heating the semiconductor integrated circuit while scanning the laser beam. Means for detecting a change in a current flowing through the internal interconnection caused by an increase in wiring resistance caused by a temperature rise due to irradiation, and in a defective portion, heat conduction is deteriorated, and the resistance of the wiring is increased from a position without a defect. Means for detecting a defect in the internal interconnection due to a larger current change.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an apparatus showing one embodiment of the present invention. The apparatus for inspecting interconnections inside a semiconductor integrated circuit includes a sample table 3 on which a sample to be inspected is placed.
The sample stage 3 has a voltage source 9 for supplying a voltage to the sample.
And a fluctuating current detection / amplification unit 8 for detecting a change in current at the moment when the laser beam is irradiated to each point of the sample, are connected via current transmission paths 13a and 13b, respectively. Further, a temperature control unit 10 for controlling the temperature of the sample is connected to the sample table 3 via a heat medium pipe 12.

A laser generator 6 for generating a laser and a laser scanner 5 for scanning the sample with the laser are provided above the sample table 3.
And a microscope unit 4 are provided.

The apparatus of this embodiment further includes a signal processing / image processing / system control unit 7 and a CRT connected thereto.
15 is provided.

Signal processing / image processing / system control unit 7
Is connected to the laser scanning unit 5, the fluctuating current detection / amplification unit 8, and the temperature control unit 10 via the signal line 14, and converts the signal into position and luminance information, and then, on the CRT 15,
The luminance is displayed as an image corresponding to the change in the current value.

Next, a description will be given of a method for detecting a defect in an interconnection inside a semiconductor integrated circuit using the inspection apparatus.

A package 2 on which a chip 1 is mounted is placed on a sample table 3. A voltage is supplied to the chip 1 from a voltage supply 9. As a result, a voltage is applied to the chip wiring. In this state, the laser generator 6 generates a laser. The generated laser is sent to the laser scanning unit 5 via the optical transmission line 11. A laser beam 17 focused from the order of μm to the order of sub μm is irradiated onto the chip 1 through the microscope unit 4 while scanning. The current flowing through the on-chip wiring changes due to the irradiation of the laser light. A change in current at each point on the chip 1 is detected by a fluctuating current detection / amplification unit 8 and signal processing / amplification is performed.
After the signal is converted into position and luminance information by the image processing / system control unit 7, the luminance is displayed on the CRT 15 as an image corresponding to the change in the current value. As there is a defect such as voids, heat conduction is poor, and as a result, the resistance in the vicinity increases,
The current change increases. Therefore, a change in contrast corresponding to a change in current can be observed. It is the same as the above-mentioned first conventional example in that the defect can not be detected on the surface and cannot be detected by the optical microscope image or the scanning electron microscope image. In order to reduce the amount of current without laser irradiation as much as possible to increase the detection sensitivity, the temperature of the chip 1 is controlled from the temperature control unit 10 via the heat medium pipe 12, and the temperature at which the current is minimized is controlled. It is also effective to carry out this inspection in.

FIG. 2 is a view showing another embodiment of the inspection apparatus of the present invention. In the present embodiment, the voltage supply source 9 in FIG.
The feature is that the SI tester 16 is replaced. Other configurations are the same as those in FIG. 1, and the same components are denoted by the same reference numerals.
The laser scanning unit 5, microscope unit 4, signal processing / image processing / system control unit 7, and temperature control unit 10 are not shown.

The LSI tester 16 is connected to the package 2 and the fluctuating current detecting / amplifying unit 8 by a current transmission path 13 as shown in the figure, and is connected to the package 2 by a signal line 31.

According to the present embodiment, by performing this inspection while supplying power and signals by the LSI tester, internal interconnections on the chip on which a current flows only in a special operation state are provided. Can also be inspected.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example,
An electron beam or an ion beam can be used instead of a laser beam.

[0022]

As described above, in the defect inspection method and apparatus according to the present invention, the temperature change of the resistance is used as the characteristic value for defect detection. Since it is only necessary to use a book, it is not necessary to align the two laser beams as in the related art, so that the irradiation laser itself can be easily scanned, and high-speed scanning can be performed, so that the image acquisition time can be greatly reduced. . In one example, the method according to the present invention, which took 6 minutes in the first conventional example, was able to realize a significant reduction of 0.5 seconds to 1 / 7,200.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing a first embodiment.

FIG. 2 is an apparatus configuration diagram showing a second embodiment.

FIG. 3 is a conceptual diagram showing a first conventional example.

FIG. 4 is a conceptual diagram showing a second conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 chip 2 package 3 sample table 4 microscope section 5 laser scanning section 6 laser generation section 7 signal processing / image processing / system control section 8 fluctuating current detection / amplification section 9 voltage supply source 10 temperature control section 11 optical transmission path 12 heat medium Pipe 13 Current transmission path (power supply line) 14, 31 Signal line 15 CRT 16 LSI tester 17 Laser 18 Pump laser generator 19 Probe laser generator 20 Pump laser 21 Probe laser 22 Thermal wave signal detector 23 Time of pump laser intensity Conceptual diagram of change 24 Conceptual diagram of temporal change in probe laser intensity 25 Conceptual diagram of reflectance detection by thermal wave signal 26 Sample 27 Semiconductor sample 28 Electron 29 Hole

Claims (9)

[Claims] 1. A semiconductor integrated circuit is irradiated and heated while scanning a laser beam in a state where a current is applied to internal interconnections of the semiconductor integrated circuit, and the internal interconnection caused by an increase in wiring resistance caused by a temperature rise due to the irradiation. A change in the current flowing in the wiring is detected, and a defect in the internal interconnection is detected by increasing the current change by increasing the resistance of the wiring from a defect-free area where the heat conduction is deteriorated and increasing the resistance of the wiring. A method for inspecting interconnections inside a semiconductor integrated circuit, comprising: 2. The method according to claim 1, wherein the current change is converted into luminance information and displayed as an image, and the current change is detected on the image. . 3. The sensitivity of the current change detection is improved by minimizing the current before the change by externally controlling the temperature of the semiconductor integrated circuit when detecting the current change. 3. The method according to claim 1, wherein the interconnects in the semiconductor integrated circuit are inspected. 4. The method according to claim 1, wherein an electron beam or an ion beam is used instead of the laser beam.
4. The method for inspecting interconnections inside a semiconductor integrated circuit according to 2 or 3. 5. A means for supplying a current to internal interconnections of a semiconductor integrated circuit, a laser beam irradiation heating means for irradiating and heating the semiconductor integrated circuit while scanning a laser beam,
Detecting a change in current flowing through the internal interconnection caused by an increase in wiring resistance due to a temperature rise due to irradiation;
Means for detecting a defect in the internal interconnection by increasing the current change by increasing the resistance of the wiring and increasing the resistance of the wiring in a defective part and the resistance of the wiring as compared with the part without the defect. Inspection system for interconnects inside semiconductor integrated circuits. 6. The interconnection according to claim 5, further comprising means for converting the current change into luminance information, displaying an image, and detecting the current change on an image. Inspection equipment. 7. The apparatus according to claim 5, further comprising means for controlling the temperature of said semiconductor integrated circuit. 8. The inspection apparatus according to claim 5, wherein an electron beam or ion beam irradiation heating means is used in place of said laser beam irradiation heating means. 9. The device according to claim 5, wherein said means for supplying a current is a voltage supply source or an LSI tester.
9. The inspection apparatus for interconnects inside a semiconductor integrated circuit according to 6, 7, or 8.