JPH04373141A - Defect detection method of semiconductor device and detection apparatus used for it - Google Patents

Abstract

PURPOSE:To detect defective portions in a semiconductor integrated circuit by using weak light emission. CONSTITUTION:A semiconductor integrated circuit containing defective portions is driven by applying a power supply and a signal. The light emission mount from the circuit in a specified period is only measured in a synchronous state to the signal. By repeating the above process, the distribution of light emission amount regarding the time of the signal is measured. The above results are compared with the light emission amount distribution of a normal integrated circuit free from defects, and whether difference exists between the light emission amounts is checked. When the difference exists, the defective portions are detected by comparing the light emission amounts in the integrated circuit surfaces in the observed period. The timing of defect generation is detected by measuring the light emission from the circuit containing the defective portions and the normal circuit so as to be synchronous to the operation timing. Hence the positions on the circuit where defective portions exist and the timing of defect generation can be easily detected, and voltage relation at the defective portions can be examined.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting defective locations in a semiconductor integrated circuit.

0002

2. Description of the Related Art As a method for detecting defective locations in semiconductor integrated circuits, there has been a method of collecting and amplifying weak light emitted from the defective locations. In this method, only power is applied to the circuit or while the circuit is operating, the light emission is accumulated for a certain period of time, and the defective location is estimated from the light emission distribution.

0003

[Problems to be Solved by the Invention] The conventional methods have the following problems. Light emission from a device occurs when carriers running inside the device lose energy, but light emission does not necessarily occur only from defective parts; for example, light emission also occurs from devices with very large gate widths. Can be seen. Therefore, since light emitted from non-defective locations is also included, it was necessary to conduct a detailed circuit analysis from all the locations that emit light to narrow down the defective locations.

SUMMARY OF THE INVENTION The present invention solves the above problems, and aims to provide a defect detection method and a detection device for use in the defect detection method that makes it easy to determine where and at what timing a defect occurs on a circuit. That is.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the defect detection method and apparatus used therein of the present invention are as follows:
A semiconductor circuit that contains a defective part and a semiconductor circuit that does not contain a defective part are operated according to a test program, and a shutter is installed on the photocathode to capture the light emitted during a certain period of time according to the test program according to the operation timing, and the light is amplified. In addition to taking in the light emission for a certain period of time on the test program, the time when this photocathode is opened is shifted on the test program, and the light emission amount distribution corresponding to each timing on the test program is obtained, and the light emission amount of these two circuits is calculated. By comparison, defective locations are detected.

[0006]

[Operation] With the above configuration, the light emission amount distribution corresponding to the test program is determined by comparing the light emission from the circuit including the defective part and the light emission from the circuit not including the defective part.
It is possible to detect when and where on the circuit a defect occurs. In addition, by calculating and simulating the light emission distribution corresponding to the timing of the test program in advance, and comparing this, it can be seen at what timing and where defects occur. This makes it possible to examine the voltage applied to defective parts, detect manufacturing process problems and design problems, and develop integrated circuits with high performance and reliability.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. First, the principle of the present invention will be explained. In a semiconductor circuit, when a power source and a signal are applied, a voltage is applied to each transistor, and when the gate and drain voltages are in a certain relationship, a light emission phenomenon is observed. For example, in the case of a MOS transistor with a gate length of about 1 micron, when the drain voltage is 5.0 V, the gate voltage is 1.5 V.
A very strong luminescence can be seen. This is because carriers running inside emit light when they lose energy. However, even if the voltage does not satisfy this relationship, if the gate width is very large, light emission will be observed, so even if light emission is observed, it cannot immediately be said that the device is defective. Furthermore, when the gate oxide film of a MOS transistor is destroyed or the wiring is short-circuited, light is emitted due to Joule heat.

Embodiments of the present invention will be described in detail below with reference to specific examples. FIG. 1 is a block diagram for explaining a defect detection method according to an embodiment of the present invention. In FIG. 1, light emitted from an integrated circuit 10 operated by a drive circuit 50 is converted into electricity by a photocathode 30, and amplified by an amplifier circuit 40. At this time, the shutter 2 synchronized with the signal of the drive circuit 50
Attach 0 to the photocathode.

A method for detecting defects using this device will be explained with reference to FIG. A test program consisting of a power supply and n signals as shown in FIG. 2(a) is applied using an LSI that includes a defective portion and an LSI that does not include a defective portion. The test program consists of 10 steps, each step taking 10 microseconds, thus making the total time 100 microseconds. First, as shown in FIG. 2(a), the shutter 20 of the photocathode 30 is opened for only 10 microseconds to sample the light emission for only 10 microseconds in the first step of the test program. The test program is 1
It runs about 1,000 times and accumulates light emission for 1,000 times. Next, the shutter 20 of the photocathode 30 is opened according to the second step of the test program, and the shutter 20 of the photocathode 30 is opened in accordance with the second step of the test program.
Accumulate 00 times. By repeating the same procedure from the third step onward, the amount of light emitted corresponding to the step of the test program is measured.

Next, the distribution of the amount of light emitted by a circuit that includes a defective portion and a circuit that does not include a defective portion will be compared. For example, if a difference occurs at the fifth step as shown in FIG. 2(c), it means that a defect occurs at the timing of the fifth step. Furthermore, as shown in FIG. 3, by looking at the light emitted within the LSI surface at this time, it can be seen that the transistor emitting light there is defective. For example, if a circuit containing a defective part has four light-emitting points 1 to 4 as shown in Figure 3(a), a normal circuit has three light-emitting points 2 to 4 as shown in Figure 3(b). If there are only 4, the first light emitting point 1
indicates the defective location. With these, it is possible to examine the voltage applied at the defective location, and to detect problems in the manufacturing process or design.

Next, another embodiment of the present invention will be explained. If the amount of light emitted at each step is simulated in advance by calculation as shown in Figure 4 without using an LSI that does not include defects, it will be possible to calculate , it becomes possible to detect defective locations. Here, the defective location is detected by comparing the in-plane light emission distribution at this timing with the in-plane light emission distribution predicted by simulation, as in the first embodiment.

0012

As described above, by using the defect detection method according to the present invention, it is easy to find out where on the circuit a defect occurs and at what timing. Therefore, manufacturing process problems and design problems can be detected, and integrated circuits with high performance and reliability can be developed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining a defect detection method according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the distribution state of the amount of light emitted with respect to signals for driving the integrated circuit, timing of opening and closing of the shutter, and signals in the integrated circuit including and not including the defective part.

FIG. 3 is a diagram illustrating the light emission distribution state of an integrated circuit including a defective portion and a normal integrated circuit.

FIG. 4 is a diagram illustrating an integrated circuit including a defective portion and a distribution state of light emission amount with respect to a signal obtained by simulation.

[Explanation of symbols]

1 to 4 Light emitting point 10 Integrated circuit 20 Shutter 30 Photocathode 40 Amplifier circuit 50 Drive circuit 60 Integrated circuit 70 including defective parts
normal integrated circuit

Claims (5)

[Claims] [Claim 1] A semiconductor device characterized in that a weak light emission from an operating semiconductor circuit including a defective part and a semiconductor circuit not including a defective part is amplified, and a defective part is detected by comparing the two. defect detection method. [Claim 2] Weak light emitted from an operating semiconductor circuit that includes a defective portion and a semiconductor circuit that does not include a defective portion is illuminated and amplified in accordance with the operating timing, and a defective portion is detected by comparing the two. A method for detecting defects in semiconductor devices, characterized in that: 3. Lighting and amplifying weak light emitted from an operating semiconductor circuit including a defective part and a semiconductor circuit not including a defective part in accordance with the operating timing, and recording the amount of light emitted at each timing, A method for detecting defects in a semiconductor device, which comprises subtracting the amount of light emitted from both, detecting the timing at which a defect occurs based on the difference, and detecting a defect location. 4. Weak light emitted from an operating semiconductor circuit is illuminated and amplified in accordance with the operating timing, the amount of light emitted at each timing is calculated in advance, and defective locations are detected by comparing the two. A method for detecting defects in semiconductor devices, characterized by: [Claim 5] A defect detection device that detects a defective portion by amplifying weak light emitted from a defective portion of a semiconductor circuit, the device comprising a shutter for collecting the emitted light in synchronization with the operation timing on the photocathode. A semiconductor device defect detection device characterized by the following.