JPH0555329A - Visual pellet inspecting device - Google Patents

Abstract

PURPOSE:To detect any foreign matters on a silicon substrate by a method wherein the diffracted beams or transmitted beams of a wafer radiated X-rays are converted into electric signals so that the converted electric signals may be compared with one another to make a decision of failure if the signals are different and to make a failure mark on the defective pellet. CONSTITUTION:The X-rays diffracted at the point near the surface of a wafer 6 are entered into X-rays detectors 3 converting the intensity data of the X-rays into electric signals to be converted into the electric signals and then transmitted to a comparator 4 for comparing them with one another. The comparator 4, according to the majority decision, specifies the pellet 2 to be the signal source of the same signal if an electric signal different from the other two signals is detected. Later, a signal is transmitted to a laser marking device 5 and a stage driving device 7 so as to make a laser mark on a defective pellet. Through these procedures, any foreign matters in a silicon substrate can be detected thereby enabling such defects as disconnection of Al wiring, fluctuation in threshold value voltage, increase in leakage current, etc., to be obviated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a pellet appearance inspection device.

[0002]

2. Description of the Related Art A conventional pellet visual inspection apparatus is an automatic one in which a machine performs the visual inspection conventionally performed by a person. The result of irradiating a pellet on a wafer with visible light is an image pickup device such as a CCD. The quality of the pellet is judged by comparing the electric signals obtained after the conversion into electric signals.

The principle of pass / fail judgment is to input electric signals of three different pellets having the same relative position to a comparison device, and the comparison device compares and inspects whether there is a difference between the three input signals. If a difference is found in any one of the three, the pellet with a difference is judged to be defective by the majority decision.

[0004]

In the conventional inspection apparatus,
Since visible light was used, foreign matter under the Al wiring, polycrystalline silicon film, etc., and foreign matter in the silicon substrate could not be inspected because visible light could not enter.
These foreign substances deteriorate the reliability of the integrated circuit by corroding the Al wiring and cutting it, changing the threshold voltage of the integrated circuit, or increasing the leak current near the PN junction. There was a problem.

[0005]

The inspection apparatus according to the present invention is provided with X
A device for generating X-rays, a device for irradiating the wafer with the generated X-rays, and an X-ray detector for converting the diffracted light rays or transmitted light rays of the X-rays irradiated on the wafer into electric signals. A comparison device is provided for comparing the electric signals, and if they are different, it is judged as a defective device, and a device for marking defective pellets for defective products when a defective device is judged.

[0006]

Since X-rays are used for the inspection, it is possible to detect a foreign substance under the Al wiring of the semiconductor integrated circuit, a foreign substance under the polycrystalline silicon, or a foreign substance in the Si substrate. Therefore, it is possible to find a foreign substance that could not be found with visible light, and improve the reliability of the semiconductor integrated circuit.

[0007]

The present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1A, the X-rays generated by the X-ray generator 1 are irradiated onto a predetermined position on the wafer 6 by the X-ray irradiation device 2. X-rays use a wavelength of about 10 ^-10 m.
The X-rays diffracted in the vicinity of the surface of the wafer 6 are incident on the X-ray detection element 3 which converts the intensity information of the X-rays into an electric signal, which is then converted into an electric signal and sent to the comparison device 4 to compare the signals. Is performed. For comparison, as shown in FIG. 1B, the X-rays reflected at the same relative positions of the three different pellets 8 on the wafer 7 are converted into electric signals by different X-ray detectors 3. It is converted and input to the comparison device 4 as an electric signal. In comparison device 4, according to the principle of majority decision, if there is a signal different from the other two regarding the electric signal, after identifying the pellet which is the signal source of the same signal, the signal is sent to laser marking device 5 and stage drive device 7. Send,
Mark the defective pellets with a laser.

Next, a second embodiment of the present invention is shown in FIG. The difference from the first embodiment is that the first embodiment uses X-ray diffracted light, whereas the second embodiment uses transmitted light. Other than this, it is the same as the previous embodiment. By using the transmitted light, not only the surface of the wafer 6 but also the deep portion can be inspected.

[0009]

As described above, since the pellet visual inspection apparatus of the present invention uses X-rays, it is possible to detect foreign matters under the Al wiring, the polycrystalline silicon film, etc. and foreign matters in the silicon substrate. Therefore, Al caused by these foreign matters
Since disconnection of wiring, fluctuation of threshold voltage, increase of leak current, etc. can be eliminated, the reliability of the integrated circuit can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment.

[Explanation of symbols]

 1 X-ray generator 2 X-ray irradiation device 3 X-ray detector 4 Comparison device 5 Laser marking device 6 Wafer 7 Stage drive device

Claims (1)

[Claims] 1. An apparatus for generating X-rays, an apparatus for irradiating the wafer with the generated X-rays, and an X-ray inspection device for converting the diffracted light or transmitted light of the X-rays irradiated on the wafer into an electric signal. Comparing the obtained electric signals, if it is different, it is composed of a comparison device for judging as defective, and a device for marking defective pellets for defective when judged defective Appearance inspection device for pellets.