JPS6073310A - Pattern inspecting apparatus - Google Patents

Abstract

PURPOSE:To inspect a defective multi-layer pattern in a single operation, by processing selectively a photo-electric converted signal obtained by irradiating a multi-layer structured specimen by a pattern photo-electric converted signal obtained by irradiating a plurality of standard patterns. CONSTITUTION:A laser ray from a laser source 4 is reflected by half-mirrors 6, 7 and reflecting mirror 8 through a deflecting system 5 and irradiates masters 13, 14 and specimen 15. The specimen 15 is composed of, for example, lower layer pattern 15a and upper layer pattern 15b and the masters 13, 14 are provided with patterns 13a, 14a corresponding to the patterns 15a, 15b. The laser ray after penetrating the masters 13, 14, is taken out as master outputs M1, M2 and the laser ray irradiating the specimen as specimen output T1. The outputs M1, M2 are processed via a selecting circuit and the output T1 is given to a plurality of switching circuits and processed by a signal processing circuit of different window widths and a defect of the specimen of the multi-layer pattern structure can be detected at a single action of inspection.

Description

[Detailed Description of the Invention] 4) Technical Field of the Invention The present invention relates to a pattern inspection device, and particularly to a pattern inspection device in which an object to be inspected is M
The present invention relates to a pattern inspection apparatus that selectively controls pattern inspection of an integrated circuit chip or the like consisting of a plurality of IN patterns using a plurality of master signals.

(2) Background of the technology When inspecting the pattern of a patterned object to be inspected, such as an integrated circuit chip, using an inspection device.

Conventional inspection equipment compares the degree of agreement between the standard pattern to be inspected, such as a mask pattern, and the inspection pattern, and if the comparison value is within a certain standard value, the pattern is the same as the standard pattern. A pattern matching method is known that determines whether there is a problem.

However, such a pattern inspection apparatus has a drawback that it cannot completely inspect a bag to be inspected in which a plurality of different patterns are laminated. For example, in the case of an object to be inspected in which there is a cover film pattern on a metal film pattern, the pattern detection signal from the metal pattern will differ depending on the presence or absence of the cover film pattern. There was a problem in which the pattern inspection of the object was not performed.

These problems will be explained in detail below.

(3) Problems with the Prior Art FIG. 1 is a plan view of an object to be inspected used in a conventional pattern inspection apparatus, and FIG. 2 shows a waveform detected by the object to be inspected.

In FIG. 1, reference numeral 1 denotes an object to be inspected for pattern inspection of, for example, an integrated circuit chip, and is made of a film having a plurality of different patterns coated with InH. Pattern 2 is drawn.

Pattern 3 is drawn on the upper membrane. The conventional pattern inspection apparatus detects only the pattern 3 formed on the upper film of the object to be inspected 1. If the laser scans the pattern in the direction indicated by the arrow, a pattern detection signal as shown in FIG. 2 (al) will be obtained.

Furthermore, as another inspection device, pattern 2.3 on the upper side as well as the lower side
When the sensor is scanned in the input direction of ``2'', pattern detection signals can be obtained from both patterns simultaneously and a waveform like that shown in Figure 2 (bl) can be obtained. No comparison can be made.The second of the latter
In the case shown in the figure (bl), it is determined whether the pattern is the same as the standard pattern based on the value of one standard level L, so the pattern inspection of pattern 3 on the upper side is performed. The same thing happens, and in order to inspect the lower pattern 2, it is necessary to make a judgment based on the value indicated by level L1, for example, but there is a drawback that it is difficult to do this in one inspection.

(4) Purpose of the Invention The present invention addresses the above-mentioned drawbacks of the conventional art.It is an object of the present invention to provide a pattern inspection device that can inspect patterns formed on each of the laminated films at the same time. It is.

(5) Structure and object of the invention According to the present invention, an object to be inspected in which patterned films are multilayered, a plurality of standard patterns such as a master for forming the pattern of the object to be inspected, and an optical comprising an irradiation means, and selectively processes a charge conversion signal obtained by irradiating the object to be inspected with light from the light irradiation means using a photoelectric conversion signal obtained by irradiating the plurality of standard patterns. This is achieved by providing a pattern inspection device characterized by having a selection processing means.

(6) Examples of the invention An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows the configuration of the optical system of the pattern inspection apparatus of the present invention.

In the figure, reference numeral 4 denotes a laser source, and the laser beam is deflected in the direction of arrow Y-Y through a deflection system 5, and is reflected by half mirrors 6, 7 and a reflecting mirror 8.
A laminated inspection object 15 made up of a plurality of first and second masks 13 and 14 and layers each having a plurality of different patterns is irradiated through the beam.

As shown in FIG.
Consists of b.

The first and second masters 13 and 14 are shown in Figure 4+bl
Patterns 13a, 14 . It has a.

The laser beam transmitted through the first and second masks 13 and 14 passes through a lens 16.17 and is applied to a sensor 19.20, where it is converted into an electrical signal and sent to the output terminal via an amplifier circuit 22.23 as a master output MIM2. Take out.

The laser beam irradiated onto the object to be inspected 15 is reflected by the object to be inspected, reflected by the half mirror 9, and the reflected light given to the sensor 18 is converted into an electrical signal, and after being amplified by the amplifier circuit 21, the output to be inspected is sent to the output terminal. Take out T1.

In the above configuration, for example, FIG.
When the laser scans the pattern shown by arrow A in 1,
The signal waveform output from sensor 1B, 19.29 is the fifth
The test object 1 with a waveform as shown in the figure (at (bl fat)
5, the waveform becomes distorted and the S/N ratio is not good. On the other hand, it is clear that the output waveforms from the masters 13 and 14 have a good S/N ratio.

Therefore, in the present invention, the region indicated by 24 of the signal waveform shown in No. 51"J++81 is replaced by the output waveform M1 of the first mask 13, and the regions indicated by 25a and 25b' are replaced by the output waveform M1 of the second master 14.
The signal processing is performed such that the signal is replaced with the output waveform M2. Such a signal processing device will be explained with reference to FIGS. 6 and 7 (al (bl).

FIG. 6 shows an example of the signal processing circuit of the present invention, and FIG.
l (bl is a waveform diagram explaining FIG. 6.

In Figure 6, M IM 2 M 3...Mn
is the output after passing through a plurality of master patterns, and one object to be inspected is composed of a laminate obtained by combining the above-mentioned plurality of master patterns, and its output is indicated as T+.

Master MIM2...Mn output selection circuit 2
6, a switching circuit 27a consisting of an AND gate, etc.;
27b......Given to one terminal of 27n.

The output T+ from the object to be inspected is transferred to switching circuits 27a, 27b,
...27n, and the outputs of the above-mentioned switching circuits 27a, 27b...27n are signal processing devices with different functions, such as window comparators each having a different window width. circuits 28a, 28
b...28n, and the outputs of these signal processing circuits are shared and output as 'r2.

To explain the operation of the above configuration, the waveform generated when the laser beam scans the object to be inspected is TI shown in Fig. 7 ta+.
If it is as shown in 29a.

In the area indicated by 29b, the switching circuit 27a to which the master signal indicated by Ml from the selection circuit 26 and the output to be tested T+ are applied is turned on, and the signal processing circuit 28a is at the level of the master signal MI.

The master signal M+ and the output to be tested T+ are compared, and the result of the comparison is, for example, as shown in FIG.
If it is entered like this, it is not output and the multi-divided output Tll of the output to be inspected is output as is. Next, in the regions 30a and 30b obtained by dividing the output to be inspected in FIG. The output T1 is compared, and the comparison result is shown in FIG. 7(b), for example.
As shown in the figure, if the multi-divided output TI2 is not included in the predetermined area level L2 of the signal processing circuit 28b, 1 is output and a waveform determined by the level of the master M2 is output. A similar comparison is made for area 31 as well.

In this case, the switching circuit 27c and the signal processing circuit 28C operate, and in the case of an object to be inspected consisting of n layers, the switching circuit 27c and the signal processing circuit 28C operate.
7n and the signal processing circuit 28n are operated.

(7) Effects of the Invention Since the present invention is configured and operates as described above, when detecting a defective part of an object to be inspected with a multilayer pattern structure, time sharing is performed for each pattern of each layer, so that each pattern is detected by a plurality of masters. It is your responsibility to carry out appropriate processing.

given name! (Also has the feature that defects can be detected in a test object having stacked patterns in a single inspection.

[Brief explanation of drawings]

Figure 1 is a plan view of a conventional test object, such as an integrated circuit chimp, in which layers with different patterns are laminated;
bl is an electrical output waveform diagram when scanning the laser beam in the direction of the arrow in FIG. 1, FIG. 3 is a configuration diagram showing the optical system of the pattern inspection apparatus of the present invention, and FIG. is a plan view showing the pattern of the inspected object and the master used in Fig. 3, and Figs. The output waveform diagram, FIG. 6 is a system diagram of the pattern inspection device of the present invention, and FIG. 7 (a
l (bl is the waveform explanatory diagram in Fig. 6. 1.12...Test object, 2.3, 15° 15a, 1
5b, 13a, 14a --- pattern. 4... Laser source, 5... Deflection system. 6.7.9...Half mirror-98...Reflecting mirror,
10.11.12.16°17...Lens, 13
．． 14...Master, 18,19.20---Sensor. 21.22.23...Amplifier circuit, T1...Test output, MIM2...Mn...Mask output,
26...Selection circuit. 27a-27n...switching circuit, 28a-28n...
・Signal processing circuit; Figure 4 Figure 5 Figure 4

Claims (1)

[Claims] An object to be inspected comprising multilayered patterned films. A photoelectric conversion signal comprising a plurality of standard patterns such as a master for forming a pattern of the object to be inspected and a light irradiation means, and obtained by irradiating the object to be inspected with light from the light irradiation means. A pattern inspection apparatus comprising a selection processing means for selectively processing a photoelectric conversion signal obtained by irradiating the plurality of standard patterns with a photoelectric conversion signal.